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Sample records for binary aquila x-1

  1. Recurrent X-ray outbursts from Aquila X-1

    NASA Technical Reports Server (NTRS)

    Kaluzienski, L. J.; Holt, S. S.; Boldt, E. A.; Serlemitsos, P. J.

    1976-01-01

    Aquila X-1 observations by the All Sky Monitor on Ariel 5 are presented. Data is compared with that obtained by rocket survey, and by the Uhuru, OSO 7, and OAO 3 satellites. The variability of brightness is discussed as a connection between dwarf novae and long term transient X ray sources.

  2. Simplified Picture of Low-Mass X-Ray Binaries Based on Data from Aquila X-1 and 4U 1608-52

    NASA Astrophysics Data System (ADS)

    Matsuoka, Masaru; Asai, Kazumi

    2013-04-01

    We propose a simplified picture of low-mass X-ray binaries containing a neutron star (NS-LMXBs) based on data obtained from Aql X-1 and 4U 1608- 52, which often produce outbursts. In this picture we propose at least three states and three state transitions: i.e., the states: (1) soft state, (2) hard-high state, and (3) hard-low state, and the state transitions: (i) hard-high state to soft state, (ii) soft state to hard-high state, and (iii) hard-high state to hard-low state or vice versa. Gases from the accretion disc of an NS-LMXB penetrate almost the entire magnetic field and accrete onto the neutron star in cases (1) and (2), whereas in case (3) some gases accrete around the magnetic poles in a manner resembling the behavior of an X-ray pulsar, and considerable gas is dispersed or ejected by the propeller effect. Transition (iii) occurs when the Alfvén radius is equal to the co-rotation radius. Therefore, in this case it is possible to estimate the strength of the neutron star's magnetic field by detecting transition (iii). We also discuss the no-accretion X-ray state or the recycled pulsar state, in which the Alfvén radius is larger than the light cylinder radius.

  3. A Semi-coherent Search for Weak Pulsations in AQUILA X--1

    NASA Astrophysics Data System (ADS)

    Messenger, C.; Patruno, A.

    2015-06-01

    Non-pulsating neutron stars in low mass X-ray binaries largely outnumber those that show pulsations. The lack of detectable pulses represents a big open problem for two important reasons. The first is that the structure of the accretion flow in the region closest to the neutron star is not well understood and it is therefore unclear what is the mechanism that prevents the pulse formation. The second is that the detection of pulsations would immediately reveal the spin of the neutron star. AQUILA X-1 is a special source among low mass X-ray binaries because it has showed the unique property of pulsating for only ˜150 s out of a total observing time of more than 1.5 million seconds. However, the existing upper limits on the pulsed fraction leave open two alternatives. Either AQUILA X-1 has very weak pulses which have been undetected, or it has genuinely pulsed only for a tiny amount of the observed time. Understanding which of the two scenarios is the correct one is fundamental to increase our knowledge about the pulse formation process and understand the chances we have to detect weak pulses in other low-mass X-ray binaries. In this paper we perform a semi-coherent search on the entire X-ray data available for AQUILA X-1. We find no evidence for (new) weak pulsations with the most stringent upper limits being of the order of 0.3% in the 7-25 keV energy band.

  4. EVOLUTION OF THE RADIO-X-RAY COUPLING THROUGHOUT AN ENTIRE OUTBURST OF AQUILA X-1

    SciTech Connect

    Miller-Jones, J. C. A.; Sivakoff, G. R.; Sarazin, C. L.; Altamirano, D.; Markoff, S.; Russell, D. M.; Tudose, V.; Migliari, S.; Fender, R. P.; Rushton, A.; Garrett, M. A.; Heinz, S.; Koerding, E. G.; Krimm, H. A.; Maitra, D.; Paragi, Z.

    2010-06-20

    The 2009 November outburst of the neutron star X-ray binary Aquila X-1 (Aql X-1) was observed with unprecedented radio coverage and simultaneous pointed X-ray observations, tracing the radio emission around the full X-ray hysteresis loop of the outburst for the first time. We use these data to discuss the disk-jet coupling, finding the radio emission to be consistent with being triggered at state transitions, both from the hard to the soft spectral state and vice versa. Our data appear to confirm previous suggestions of radio quenching in the soft state above a threshold X-ray luminosity of {approx}10% of the Eddington luminosity. We also present the first detections of Aql X-1 with very long baseline interferometry, showing that any extended emission is relatively diffuse and consistent with steady jets rather than arising from discrete, compact knots. In all cases where multi-frequency data were available, the source radio spectrum is consistent with being flat or slightly inverted, suggesting that the internal shock mechanism that is believed to produce optically thin transient radio ejecta in black hole X-ray binaries is not active in Aql X-1.

  5. X-Ray Emission from the Soft X-Ray Transient Aquila X-1

    NASA Technical Reports Server (NTRS)

    Tavani, Marco

    1998-01-01

    Aquila X-1 is the most prolific of soft X-ray transients. It is believed to contain a rapidly spinning neutron star sporadically accreting near the Eddington limit from a low-mass companion star. The interest in studying the repeated X-ray outbursts from Aquila X-1 is twofold: (1) studying the relation between optical, soft and hard X-ray emission during the outburst onset, development and decay; (2) relating the spectral component to thermal and non-thermal processes occurring near the magnetosphere and in the boundary layer of a time-variable accretion disk. Our investigation is based on the BATSE monitoring of Aquila X-1 performed by our group. We observed Aquila X-1 in 1997 and re-analyzed archival information obtained in April 1994 during a period of extraordinary outbursting activity of the source in the hard X-ray range. Our results allow, for the first time for this important source, to obtain simultaneous spectral information from 2 keV to 200 keV. A black body (T = 0.8 keV) plus a broken power-law spectrum describe accurately the 1994 spectrum. Substantial hard X-ray emission is evident in the data, confirming that the accretion phase during sub-Eddington limit episodes is capable of producing energetic hard emission near 5 x 10(exp 35) ergs(exp -1). A preliminary paper summarizes our results, and a more comprehensive account is being written. We performed a theoretical analysis of possible emission mechanisms, and confirmed that a non-thermal emission mechanism triggered in a highly sheared magnetosphere at the accretion disk inner boundary can explain the hard X-ray emission. An anticorrelation between soft and hard X-ray emission is indeed prominently observed as predicted by this model.

  6. Aquila

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    (the Eagle; abbrev. Aql, gen. Aquilae; area 652 sq. deg.) An equatorial constellation that lies between Sagitta and Sagittarius, and culminates at midnight in mid-July. Its origin dates back to Babylonian times and it is said to represent the eagle of Zeus in Greek mythology, which carried the thunderbolts that Zeus hurled at his enemies and which snatched up Ganymede to become cup-bearer to the g...

  7. Discovery of hard X-ray outbursts from the soft X-ray transient Aquila X-1.

    NASA Astrophysics Data System (ADS)

    Harmon, B. A.; Wilson, C. A.; Tavani, M.; Zhang, S. N.; Rubin, B. C.; Paciesas, W. S.; Ford, E. C.; Kaaret, P.

    1996-11-01

    We report the BATSE discovery of hard X-ray outbursts from the soft X-ray transient Aquila X-1 (Aql X-1). Aql X-1 is the most prolific of the soft X-ray transient sources and it has been known to produce large outbursts near the Eddington limit in the 1-10keV energy band. The typical recurrence time of outbursts is about 1-year. Aql X-1 shows type I X-ray bursts during the decay phase of the X-ray outbursts and is believed to contain a neutron star. These characteristics of Aql X-1 make it an ideal system to study time variable hard X-ray emission from accreting neutron stars. BATSE has monitored Aql X-1 continuously since the Compton Observatory mission began in April 1991. Several episodes of hard X-ray emission with durations of weeks to months have been detected in 1991-1994. These episodes are coincident with substantial brightening of the optical counterpart and to a lesser degree with observations of soft X-ray emission by ROSAT, EURECA/WATCH and ASCA. We find fluxes in the 20-100mCrab range with hard spectra extending to above 100keV and power law spectral fits yielding photon indices between -2 and -3.

  8. NGC 300 X-1 and IC 10 X-1: a new breed of black hole binary?

    NASA Astrophysics Data System (ADS)

    Barnard, R.; Clark, J. S.; Kolb, U. C.

    2008-09-01

    Context: IC 10 X-1 has recently been confirmed as a black hole (BH) + Wolf-Rayet (WR) X-ray binary, and NGC 300 X-1 is thought to be. The only other known BH+WR candidate is Cygnus X-3. IC 10 X-1 and NGC 300 X-1 have similar X-ray properties, with 0.3-10 keV luminosities ~1038 erg s-1, and their X-ray lightcurves exhibit orbital periods ~30 h. Aims: We investigate similarities between IC 10 X-1 and NGC 300 X-1, as well as differences between these systems and the known Galactic BH binary systems. Methods: We have examined all four XMM-Newton observations of NGC 300 X-1, as well as the single XMM-Newton observation of IC 10 X-1. For each observation, we extracted lightcurves and spectra from the pn, MOS1 and MOS2 cameras; power density spectra were constructed from the lightcurves, and the X-ray emission spectra were modeled. Results: Each source exhibits power density spectra that are well described by a power law with index, γ, ~1. Such variability is characteristic of turbulence in wind accretion or disc-accreting X-ray binaries (XBs) in the high state. In this state, Galactic XBs with known BH primaries have soft, thermal emission; however the emission spectra of NGC 300 X-1 and IC 10 X-1 in the XMM-Newton observations are predominantly non-thermal. Furthermore, the Observation 1 spectrum of NGC 300 X-1 is strikingly similar to that of IC 10 X-1. Conclusions: The remarkable similarity between the behaviour of NGC 300 X-1 in Observation 1 and that of IC 10 X-1 lends strong evidence for NGC 300 X-1 being a BH+WR binary. Our spectral modeling rules out Bondi-Hoyle accretion onto a neutron star (NS) for NGC 300 X-1, but not a disc-accreting NS+WR system, nor a NS low mass X-ray binary (LMXB) that is merely coincident with the WR. We favour disc accretion for both systems, but cannot exclude Bondi-Hoyle accretion onto a BH. The unusual spectra of NGC 300 X-1 and IC 10 X-1 may be due to these systems existing in a persistently high state, whereas all known BH LMXBs

  9. The 1978 X-ray and optical outburst of Aquila X-1 /4U 1908+00/

    NASA Astrophysics Data System (ADS)

    Charles, P. A.; Thorstensen, J. R.; Bowyer, S.; Clark, G. W.; Li, F. K.; van Paradijs, J.; Remillard, R.; Holt, S. S.; Kaluzienski, L. J.; Junkkarinen, V. T.; Puetter, R. C.; Smith, H. E.; Pollard, G. S.; Sanford, P. W.; Tapia, S.; Vrba, F. J.

    1980-04-01

    During the summer of 1978 the recurrent transient X-ray source, Aquila X-1, underwent its first major outburst in two years. This paper presents the results of extensive X-ray and optical observations of this event, which lasted for about two months. The peak X-ray luminosity was about 1.3 times that of the Crab and exhibited spectrum-dependent flickering on time scales of about 5 minutes. In addition, one very large flare was observed about one month after maximum that was also correlated with spectral changes. During this flare the previously identified optical counterpart brightened from V = 19 to a peak of V = 14.8, where it was distinctly blue (U - B = 0.4), and then reddened during the decay. These observations are interpreted in terms of a standard accretion disk model with particular emphasis on the similarities to Sco -1 and other dwarf X-ray systems.

  10. The 1978 X-ray and optical outburst of Aquila X-1 /4U 1908+00/

    NASA Technical Reports Server (NTRS)

    Charles, P. A.; Thorstensen, J. R.; Bowyer, S.; Clark, G. W.; Li, F. K.; Van Paradijs, J.; Remillard, R.; Holt, S. S.; Kaluzienski, L. J.; Junkkarinen, V. T.

    1980-01-01

    During the summer of 1978 the recurrent transient X-ray source, Aquila X-1, underwent its first major outburst in two years. This paper presents the results of extensive X-ray and optical observations of this event, which lasted for about two months. The peak X-ray luminosity was about 1.3 times that of the Crab and exhibited spectrum-dependent flickering on time scales of about 5 minutes. In addition, one very large flare was observed about one month after maximum that was also correlated with spectral changes. During this flare the previously identified optical counterpart brightened from V = 19 to a peak of V = 14.8, where it was distinctly blue (U - B = 0.4), and then reddened during the decay. These observations are interpreted in terms of a standard accretion disk model with particular emphasis on the similarities to Sco -1 and other dwarf X-ray systems.

  11. Superhumps in Cataclysmic Binaries. XI. V603 Aquilae Revisited

    NASA Astrophysics Data System (ADS)

    Patterson, J.; Kemp, J.; Saad, J.; Skillman, D. R.; Harvey, D.; Fried, R.; Thorstensen, J. R.; Ashley, R.

    1997-04-01

    After a decade of near stability at P=0.146 d, the photometric "superhump" periodicity of the old nova V603 Aquilae experienced a remarkable change between 1991 and 1992. Observation in 1992--1994 indicates that the dominant signal was then at a period in the range 0.1338-0.1345 d, 3% shorter than the orbital period. Like its predecessor, the new signal also wanders in period on a timescale of a few months. The full amplitude in 1994 was 0.20 mag, more than twice as great as the superhump displayed during 1980--1991. An intensive observing campaign in 1994 revealed that the old superhump at 0.146 d was still present with approximately undiminished amplitude (averaging 0.07 mag). In a precession model, the simultaneous presence of superhumps above and below the orbital period strongly suggests identification with two independent types of precessional sideband. The observed periods and period changes are consistent with a simple hypothesis: that the longer period ("positive superhump") arises from the prograde motion of the line of apsides, and the shorter period ("negative superhump") arises from the retrograde motion of the line of nodes. A detailed account of how a fluid disk manages to maintain such well-organized motions is sorely needed. (SECTION: Special Issue on Cataclysmic Variable Stars)

  12. Hard X-Ray Flares Preceding Soft X-Ray Outbursts in Aquila X-1: A Link between Neutron Star and Black Hole State Transitions

    NASA Astrophysics Data System (ADS)

    Yu, Wenfei; Klein-Wolt, Marc; Fender, Rob; van der Klis, Michiel

    2003-05-01

    We have analyzed Rossi X-Ray Timing Explorer data of the neutron star transient Aquila X-1 obtained during its outbursts in 1999 May/June and 2000 September/October. We find that in the early rise of these outbursts, a hard flare in the energy range above 15 keV preceded the soft X-ray peak. The hard X-ray flux of the hard flares at maximum was more than a factor of 3 stronger than at any other point in the outbursts. The rise of the hard X-ray flare to this maximum was consistent with a monotonically brightening low-/hard-state spectrum. After the peak of the hard flare, a sharp spectral transition occurred with spectral pivoting in the range 8-12 keV. Our timing analysis shows that during the hard flare, the power spectra were composed mainly of band-limited noise and a ~1-20 Hz quasi-periodic oscillation (QPO), which correlate in frequency. Immediately after the hard flare, the power spectra turned into power-law noise. The spectral and timing properties during and after the hard flares are very similar to those in black hole transients during the early rise of an outburst. We suggest that these hard flares and spectral transitions in Aql X-1 are of the same origin as those observed in black hole transients. This leads to the association of the 1-20 Hz QPOs and band-limited noise in Aql X-1 with those in black hole transients. We discuss the impact of this discovery on our understanding of soft X-ray transient outbursts, state transitions, and variability in X-ray binaries.

  13. Photometric study of the active binary star V1430 Aquilae

    NASA Astrophysics Data System (ADS)

    Erdem, A.; Sürgit, D.

    2006-05-01

    New BVR light curves and a photometric analysis of the eclipsing binary star V1430 Aql are presented. The light curves were obtained at the Çanakkale Onsekiz Mart University Observatory in 2004. The light curves are generally those of detached eclipsing binaries, but there are large asymmetries between maxima. New BVR light curves were analysed with an ILOT procedure. Light curve asymmetries of the system were explained in terms of large dark starspots on the primary component. The primary star shows a long-lived and quasi-poloidal spot distribution with active longitudes in opposite hemispheres. Absolute parameters of the system were derived. We also discuss the evolution of the system: the components are likely to be pre-main sequence stars, but a post-main sequence stage cannot be ruled out. More observations are needed to decide this point.

  14. Thermonuclear flash model for long X-ray tails from Aquila X-1

    NASA Technical Reports Server (NTRS)

    Fushiki, Ikko; Taam, Ronald E.; Woosley, S. E.; Lamb, D. Q.

    1992-01-01

    Attention is given to a thermonuclear flash model for long X-ray tails from the recurrent transient Aql X-1, in which the extended phase of nuclear burning is due to the fact that the envelope is out of thermal equilibrium. Only the first X-ray burst emitted by Aql X-1 during its transient outburst exhibits a long X-ray tail. The properties of subsequent bursts are distinguished by a lack of an X-ray tail reflecting the much smaller accumulated masses which result from the effects of thermal inertia in the neutron star envelope. The characteristics of the latter bursts are similar to those of typical X-ray bursters. For a neutron star characterized by a mass and radius of 1.4 solar mass and 9.1 km, respectively, the occurrence of the long X-ray tail requires that the mass of the accumulated layer be less than 10 exp 23 g and that the envelope temperatures of the neutron star be less than 1.5 x 10 exp 7. This interpretation is found to be consistent with the thermal relaxation of the neutron star envelope during the quiescent state of Aql X-1 and with the mass accretion rates inferred for the transient outburst itself.

  15. Slow and Fast Transitions in the Rising Phase of Outbursts from NS-LMXB Transients, Aquila X-1 and 4U 1608-52

    NASA Astrophysics Data System (ADS)

    Asai, Kazumi; Matsuoka, Masaru; Mihara, Tatehiro; Sugizaki, Mutsumi; Serino, Motoko; Nakahira, Satoshi; Negoro, Hitoshi; Ueda, Yoshihiro; Yamaoka, Kazutaka

    2012-12-01

    We analyzed the initial rising behaviors of X-ray outbursts from two transient low-mass X-ray binaries (LMXBs) containing a neutron-star (NS), Aquila X-1 (Aql X-1) and 4U 1608-52, which are continuously being monitored by MAXI/GSC in 2-20 keV, RXTE/ASM in 2-10 keV, and Swift/BAT in 15-50 keV. We found that the observed ten outbursts can be classified into two types based on the patterns of the relative intensity evolutions in the two energy bands below/above 15 keV. One type behaves as the 15-50 keV intensity achieves the maximum during the initial hard-state period, and drops greatly at the hard-to-soft state transition. On the other hand, the other type does as both the 2-15 keV and 15-50 keV intensities achieve the maximums after the transition. The former have the longer initial hard-state (gtrsim 9 d) than the latter (lesssim 5 d). Therefore, we named them as slow-type (S-type) and fast-type (F-type), respectively. These two types also show differences in the luminosity at the hard-to-soft state transition as well as in the average luminosity before the outburst started, where the S-type are higher than the F-type in both. These results suggest that the X-ray radiation during the pre-outburst period, which heats up the accretion disk and delays the disk transition (i.e., from a geometrically thick disk to a thin one), would determine whether the following outburst becomes S-type or F-type. The luminosity when the hard-to-soft state transition occurs is higher than ˜8 × 1036 erg s-1 in the S-type, which corresponds to 4% of the Eddington luminosity for a 1.4 M⊙ NS.

  16. Analysis of the Extreme Mass Ratio, High Contact Eclipsing Binary, V802 Aquilae

    NASA Astrophysics Data System (ADS)

    Samec, R. G.; Martin, M. W.; Faulkner, D. R.

    2004-05-01

    We present our observations and initial analysis of BVRI light curves of the solar type, high contact binary, V802 Aquilae [GSC 5119 948, α (2000) = 18h 58m 54.82s, δ (2000) = -03° 01' 11.5"]. The observations were taken on the evenings of 5, 6 and 8 June 2002, by RGS and DRF with the 0.9-m reflector at CTIO. Standard UBVRcIc filters were used. We took from 138 to 148 observations in each BVRI pass band and about 100 in U. Mean epochs of minimum light for one primary eclipse, HJD = 2452431.82156 (81) as well as two secondary eclipses 2452434.89764 (11) and 2452432.75617 (21) were calculated. We calculated the following linear ephemeris: J.D. Hel Min I = 2450300.43417 (69) + 0.26769479 (11) d*E. (2) The light curves are shallow (0.35 mag in V) yet show a broad time of constant light (width about 0.1 phase) in the secondary eclipse. Its depressed primary maxima (about 0.06 mag in B) suggest the presence of heavy spot activity. Our Wilson code BVRI simultaneous solution of the instrumental magnitude light curves yields a mass ratio of M2/M1 = 0.16, and a fill-out 32.7 %. The temperature difference is T2-T1 = 136 K with the tiny secondary component having the higher mean surface temperature. A 20.2° cool spot was modeled on the primary component. Its longitude, co-latitude and temperature factor were 281° , 67° , and 0.915 respectively. Further results are presented. The system is a part of a rare group of binaries with a very low mass secondary and high mass ratio that are near a phase of final coalescence into an FK Comae type star. Much of the work was done by an undergraduate student, MWM. We wish to thank Cerro Tololo InterAmerican Observatory for their allocation of observing time, and the grant from NASA administered by the American Astronomical Society.

  17. Low-frequency QPOs and Possible Change in the Accretion Geometry during the Outbursts of Aquila X-1

    NASA Astrophysics Data System (ADS)

    Zhang, Wenda; Yu, Wenfei

    2015-06-01

    We have studied the evolution of low-frequency quasi-periodic oscillations (LFQPOs) during the rising phase of seven outbursts of the neutron star soft X-ray transient Aql X-1 observed with the RXTE. A frequency correlation between the low-frequency break and the LFQPO sampled on a timescale of ˜2 days was observed. Except for the peculiar 2001 outburst, the frequency of LFQPOs increased with time before the hard-to-soft state transition up to a maximum {{ν }max } at ˜31 Hz, a factor of ˜5 higher than those seen in BH transients such as GX 339-4, making the maximum quasi-periodic oscillation (QPO) frequency a likely indicator of the mass of the central compact object. The characteristic frequencies increased by around 10% per day in the early rising phase and accelerated to nearly 100% per day since ˜2 days before the hard-to-soft state transition. We examined the dependence of the frequency {{ν }LF} on the source flux f and found an anti-correlation between the maximum frequency of the LFQPOs and the corresponding X-ray luminosity of the hard-to-soft transition (or outburst peak luminosity) among the outbursts. We suggest that the X-ray evaporation process cannot be the only mechanism that drives the variation of the inner disk radius if either of the twin kHz QPOs corresponds to the Keplerian frequency at the truncation radius.

  18. Discovery of the binary nature of SMC X-1 from Uhuru.

    NASA Technical Reports Server (NTRS)

    Schreier, E.; Giacconi, R.; Gursky, H.; Kellogg, E.; Tananbaum, H.

    1972-01-01

    The X-ray source in the Small Magellanic Cloud SMC X-1 was observed by Uhuru on numerous occasions from December 1970 through April 1972. As previously reported by Leong et al. (1971), the source was seen to be variable. It was found that SMC X-1 occults with a period of 3.8927 days. The energy spectrum is cut off at low energies and flat. There is no large-amplitude periodic pulsation. The luminosity observed makes the binary source SMC X-1 comparable in strength to both the stronger galactic sources and the discrete sources in the Large Magellanic Cloud.

  19. A Decade in the Life of the Massive Black-Hole Binary IC10 X-1

    NASA Astrophysics Data System (ADS)

    Laycock, Silas

    2014-11-01

    Chandra thanks to its angular resolution, sensitivity and endurance has been able to monitor individual X-ray binaries in the starburst galaxy IC 10. The WR+BH binary known as IC10 X-1 is regarded as one of the most massive stellar black holes; a class of objects representing the pinnacle of the stellar mass function. BH binaries occupy key roles in seeding SMBHs, producing long GRBs at birth, and gravitational waves at death. We report our use of Chandra to refine the orbital ephemeris of X1 and match-up the radial velocity curve of the optical spectral lines with the X-ray eclipse. The resulting phase offset has fascinating implications for our understanding of the interactions between the WR star, its wind, and the radiation field of the BH.

  20. Timing and Spectral Studies of the Peculiar X-ray Binary Circinus X-1

    SciTech Connect

    Saz Parkinson, Pablo M.

    2003-08-26

    Circinus X-1 (Cir X-1) is an X-ray binary displaying an array of phenomena which makes it unique in our Galaxy. Despite several decades of observation, controversy surrounds even the most basic facts about this system. It is generally classified as a Neutron Star (NS) Low Mass X-ray Binary (LMXB),though this classification is based primarily on the observation of Type I X-ray Bursts by EXOSAT in 1985. It is believed to be in a very eccentric {approx} 16.5 day orbit, displaying periodic outbursts in the radio and other frequency bands (including optical and IR) which reinforce the notion that this is in fact the orbital period. Cir X-1 lies in the plane of the Galaxy, where optical identification of the companion is made difficult due to dust obscuration. The companion is thought to be a low mass star, though a high mass companion has not currently been ruled out. In this work, the author analyzes recent observations of Cir X-1 made with the Unconventional Stellar Aspect (USA) experiment, as well as archival observations of Cir X-1 made by a variety of instruments, from as early as 1969. The fast (< 1 s) timing properties of Cir X-1 are studied by performing FFT analyses of the USA data. Quasi-Periodic Oscillations (QPOs) in the 1-50 Hz range are found and discussed in the context of recent correlations which question the leading models invoked for their generation. The energy dependence of the QPOs (rms increasing with energy) argues against them being generated in the disk and favors models in which the QPOs are related to a higher energy Comptonizing component. The power spectrum of Cir X-1 in its soft state is compared to that of Cygnus X-1 (Cyg X-1), the prototypical black hole candidate. Using scaling arguments the author argues that the mass of Cir X-1 could exceed significantly the canonical 1.4 M{circle_dot} mass of a neutron star, possibly partly explaining why this object appears so different to other neutron stars. The spectral evolution of Cir X-1 is

  1. The youngest known X-ray binary: Circinus X-1 and its natal supernova remnant

    SciTech Connect

    Heinz, S.; Sell, P.; Fender, R. P.; Jonker, P. G.; Brandt, W. N.; Calvelo-Santos, D. E.; Tzioumis, A. K.; Nowak, M. A.; Schulz, N. S.; Wijnands, R.; Van der Klis, M.

    2013-12-20

    Because supernova remnants are short-lived, studies of neutron star X-ray binaries within supernova remnants probe the earliest stages in the life of accreting neutron stars. However, such objects are exceedingly rare: none were known to exist in our Galaxy. We report the discovery of the natal supernova remnant of the accreting neutron star Circinus X-1, which places an upper limit of t < 4600 yr on its age, making it the youngest known X-ray binary and a unique tool to study accretion, neutron star evolution, and core-collapse supernovae. This discovery is based on a deep 2009 Chandra X-ray observation and new radio observations of Circinus X-1. Circinus X-1 produces type I X-ray bursts on the surface of the neutron star, indicating that the magnetic field of the neutron star is small. Thus, the young age implies either that neutron stars can be born with low magnetic fields or that they can rapidly become de-magnetized by accretion. Circinus X-1 is a microquasar, creating relativistic jets that were thought to power the arcminute-scale radio nebula surrounding the source. Instead, this nebula can now be attributed to non-thermal synchrotron emission from the forward shock of the supernova remnant. The young age is consistent with the observed rapid orbital evolution and the highly eccentric orbit of the system and offers the chance to test the physics of post-supernova orbital evolution in X-ray binaries in detail for the first time.

  2. Radial velocity studies and absolute parameters of contact binaries. II - OO Aquilae

    NASA Technical Reports Server (NTRS)

    Hrivnak, Bruce J.

    1989-01-01

    New high-precision radial velocities of the contact binary OO Aql have been obtained using the cross-correlation technique. The orbital elements have been corrected for proximity effects, using an analysis of published light curves of the system. The spectroscopically determined mass ratio of 0.843 is in excellent agreement with the photometrically determined value. OO Aql thus has one of the largest mass ratios observed for a contact binary. In contrast to almost all other contact binaries of G spectral type, the primary minimum is due to a transit by the less massive component, and thus the system is classified as an A-type contact binary. Absolute parameters are determined for OO Aql, which indicate that the primary component, although similar to the Sun in mass, is significantly more evolved. An age of about 8 Gyr and a metal abundance of one-half that of the Sun are determined. It seems that the system may have only recently evolved into contact, as suggested by Mochnacki, and that it is an important object for studies of the structure and evolution of contact binaries.

  3. Timing and spectral studies of the peculiar x-ray binary Circinus X-1

    NASA Astrophysics Data System (ADS)

    Parkinson, Pablo Miguel Saz

    Cir X-1 is a unique Galactic X-ray binary which was initially classified as a black hole candidate but later reclassified as a neutron star due primarily to the observation of Type I X-ray Bursts by EXOSAT in 1985. In this work, I examine the timing and spectral properties of Cir X-1. FFT analyses are used to study the short (<1 s) timescales while Lomb-Scargle and Phase Dispersion Minimization periodograms are computed to study longer timing properties. I analyze Quasi-Periodic Oscillations (QPO) in the 1-50 Hz range and divide them into lower frequency (˜3--20 Hz) and higher frequency ones (˜15--50 Hz). The high frequency QPOs decrease in strength (% rms) with increasing frequency, while the lower frequency ones stay constant. The energy dependence of the QPOs implies the frequency is not representative of different locations in the disk. The power spectrum of Cir X-1 in its softest state is compared to Cyg X-1. Both show breaks. By using scaling arguments, I hypothesize that Cir X-1 has a mass of ˜3 M⊙ , greater than the canonical 1.4 M⊙ mass of a neutron star. I study the energy spectrum evolution of Cir X-1 by constructing both instrument-independent and model-independent color-color diagrams. Spectral fits were performed on USA data, from which physical parameters were derived. The spectral parameters indicate that a two-component model is valid for describing the Cir X-1 spectrum: a multicolor blackbody emission from an accretion disk and a Comptonized emission from a hot plasma (boundary layer or corona). The temperature of the disk remains constant, while there is an indication that the Comptonizing component increases in temperature with orbital phase. From the relative contribution of the disk I infer the neutron star is spinning very rapidly (>1 kHz). The long-term variability of Cir X-1 is studied using data from instruments going back over thirty years. I derive an X-ray ephemeris based showing that the period of Cir X-1 decreases rapidly (P

  4. OO Aquilae: a solar-type contact binary with intrinsic light curve changes

    NASA Astrophysics Data System (ADS)

    Li, Hua-Li; Wei, Jian-Yan; Yang, Yuan-Gui; Dai, Hai-Feng

    2016-01-01

    New multi-color photometry of the solar-type contact binary OO Aql was obtained in 2012 and 2013, using the 60 cm telescope at Xinglong Station of the National Astronomical Observatories, Chinese Academy of Sciences. From two sets of light curves LC1 and LC2, photometric models were performed by using the 2003 version of the Wilson-Devinney code. The overcontact factor of the binary system was determined to be f = 37.0(±0.5)%. The intrinsic variability of this binary occurs in light maxima and minima, which could result from a possible third component and magnetic activity of the late type components. Based on all available light minimum times, the orbital period may change in a complicated mode, i.e., sudden period jumps or continuous period variations. The period of OO Aql may possibly undergo a secular period decrease with a rate of dP/dt = -3.63(±0.30) × 10-8 d yr-1, superimposed by two possible cyclic variations in the O - C curve. The long-term period decrease may be interpreted as conserved mass transfer from the more massive component to the less massive one. The 21.5-yr oscillation may be attributed to cyclic magnetic activity, and the 69.3-yr one may result from the light-time effect of an unseen tertiary body.

  5. Investigating the Wolf-Rayet + Black Hole Binary NGC 300 X-1 With Chandra and Hubble

    NASA Astrophysics Data System (ADS)

    Gross, Jacob; Binder, Breanna A.; Williams, Benjamin F.; Laycock, Silas

    2016-01-01

    We observed the Wolf-Rayet + black hole binary NGC 300 X-1 twice with the Chandra X-ray Observatory (~65 ksec each). In the first observation, we observed a secular increase in brightness of the X-ray source, consistent with an eclipse egress. The Chandra data were also used to construct a spectral model of the black hole that could help us better understand how X-rays are being produced in the binary. We observe an X-ray energy dependence on the orbital phase, consistent with the black hole moving through the dense stellar wind of the donor star. Prior to our study, NGC 300 X-1 had only been observed by ground-based telescopes and these images of the system made it difficult to separate the optical source from other nearby stars. We obtained Hubble imaging of NGC 300 X-1 for the first time, and found a bright AGB star withing the X-ray error circle, in addition to the Wolf-Rayet star. We cannot rule out the possibility that the AGB star is the companion. We have compared the X-ray light curve with the He II λ 4648 emission line radial velocity from the literature to the X-ray light curve, and found that the He II emission line likely originates from the black hole accretion disk or from a focused wind from the donor, and not the donor star itself. These observations demonstrates that the mass of the black hole -- previously estimated at ~15 M⊙ -- may not be accurate.

  6. Morphology and kinematics of the gas envelope of the Mira binary W Aquilae

    NASA Astrophysics Data System (ADS)

    Thi Hoai, Do; Tuyet Nhung, Pham; Diep, Pham Ngoc; Thi Phuong, Nguyen; Tuan-Anh, Pham; Thi Thao, Nguyen; Darriulat, Pierre

    2016-07-01

    We analyse ALMA observations of the 12CO(3-2) emission of the circumstellar envelope (CSE) of the Mira variable binary star W Aql. These provide, for the first time, spatially resolved Doppler velocity spectra of the CSE up to angular distances to the central star of ∼ 5″ (meaning some 2000 AU). The exploratory nature of the observations (only five minutes in each of two different configurations) does not allow for a detailed modelling of the properties of the CSE but provides important qualitative information on its morphology and kinematics. Emission is found to be enhanced along an axis moving from east/west to north-east/south-west when the angular distance from the central star projected on the plane of the sky increases from zero to four arcseconds. In parallel, the Doppler velocity distribution displays asymmetry along an axis moving from east/west to north-west/south-east. The results are discussed in the context of earlier observations, in particular of the dust morphology. ) operated by the NAOJ.

  7. On the orbital and physical parameters of the HDE 226868/Cygnus X-1 binary system

    NASA Astrophysics Data System (ADS)

    Iorio, Lorenzo

    2008-06-01

    In this paper we explore the consequences of the recent determination of the mass m=(8.7±0.8) M ⊙ of Cygnus X-1, obtained from the Quasi-Periodic Oscillation (QPO)-photon index correlation scaling, on the orbital and physical properties of the binary system HDE 226868/Cygnus X-1. By using such a result and the latest spectroscopic optical data of the HDE 226868 supergiant star we get M=(24±5) M ⊙ for its mass. It turns out that deviations from the third Kepler law significant at more than 1-sigma level would occur if the inclination i of the system’s orbital plane to the plane of the sky falls outside the range ≈41 56 deg: such deviations cannot be due to the first post-Newtonian (1PN) correction to the orbital period because of its smallness; interpreted in the framework of the Newtonian theory of gravitation as due to the stellar quadrupole mass moment Q, they are unphysical because Q would take unreasonably large values. By conservatively assuming that the third Kepler law is an adequate model for the orbital period we obtain i=(48±7) deg which yields for the relative semimajor axis a=(42±9) R ⊙ (≈0.2 AU).

  8. Understanding Black Hole X-ray Binaries: The Case of Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Pottschmidt, Katja

    2008-01-01

    Black Hole X-ray Binaries are known to display distinct emission states that differ in their X-ray spectra, their X-ray timing properties (on times scales less than 1 s) and their radio emission. In recent years monitoring observations, specially with NASA's Rossi X-ray Timing Explorer (RXTE), have provided us with detailed empirical modeling of the phenomenology of the different states as well as a unification scheme of the long term evolution of black holes, transient and persistent, in terms of these states. Observations of the persistent High Mass X-ray Binary (HMXB) Cygnus X-l have been at the forefront of learning about black hole states since its optical identification through a state transition in 1973. In this talk I will present in depth studies of several different aspects of the accretion process in this system. The main data base for these studies is an ongoing RXTE and Ryle radio telescope bi-weekly monitoring campaign that started in 1997. I will discuss high-resolution timing results, especially power spectra, which first gave rise to the Lorentzian description now widely used for black hole and neutron star binaries, and time lags, which we found to be especially well suited to identify state transitions. The evolution of spectral, timing, and radio parameters over years will be shown, including the rms-flux relation and the observation of a clearly correlated radio/x-ray flare. We also observed Cygnus X-1 with INTEGRAL, which allowed us to extend timing and spectral studies to higher energies, with XMM, which provided strong constraints on the parameters of the 6.4 keV iron fluorescence line, and with Chandra, which provided the most in depth study to date of the stellar wind in this system. Models based on the physical conditions in the accretion region are still mainly concentrated on the one or other of the observational areas but they are expanding: as an example I will review results from a jet model for the quantitative description of the

  9. Optical and UV spectroscopy of the black hole binary candidate LMC X-1

    NASA Technical Reports Server (NTRS)

    Hutchings, J. B.; Crampton, D.; Cowley, A. P.; Bianchi, L.; Thompson, I. B.

    1987-01-01

    Both further optical spectroscopy of the binary star identified with LMC X-1, obtained between 1983 and 1985, and a series of IUE UV spectra taken during a 5 day interval in 1984 are presented. The optical data are used to refine the orbital period to 4.2288 days, and improved orbital parameters are derived. The velocity of the optical emission lines is antiphased with the absorption lines and has twice the velocity amplitude. These new results support the estimates of the masses in the system given earlier. The most probable component masses are approximately 20 solar masses for the primary and near 6 solar masses (for the x-ray star), suggesting the the latter may be a black hole. The UV spectra show very weak, low-velocity stellar-wind lines. It is suggested that much of the surrounding medium is highly ionized by the X-ray flux. The 'nonwind' UV spectral lines and the UV continuum temperature are consistent with the optical data, indicating a late O type star of M(bol) = -8.5. There is a weak modulation of absorption-line strengths with orbital phase, suggestive of a lack of axisymmetry in the X-irradiation of the primary star and indicative of a fairly low orbital inclination.

  10. Activities of X-ray binaries accompanied by a neutron star with weak magnetic field: Cir X-1, Aql X-1 and 4U 1608-52

    NASA Astrophysics Data System (ADS)

    Matsuoka, Masaru; Mihara, Tatehiro; Asai, Kazumi

    This paper is presented on X-ray activities of X-ray binaries accompanied by a neutron star with weak magnetic field. Neutron star low mass X-ray binaries (NS-LMXBs) have been well studied so far, but there are still unknown problems concerning activities of outbursts and X-ray spectral features. We can define the soft and hard states which show different spectra created from each disk structure. These states depend on the gas accretion rate causing viscosity change in the disk, whereas we have pointed out an importance of magnetic field in NS-LMXB for X-ray activities (Matsuoka & Asai 2013). Thus, we have obtained decay features occurred by a propeller effect for Aql X-1 and 4U1608-52, and thus, we have defined the propeller effect levels of these sources (Asai et al. 2013). A companion star of Cir X-1 is a star of B5~A0 type, but it has X-ray spectral feature similar to NS-LMXB as well as it produced type I X-ray bursts. A long history over 40 years of X-ray observations has provided that Cir X-1 X-ray intensities have many varieties from continuous variable fluxes with Z-type feature of NS-LMXB to recurrent outburst fluxes with Atoll-type feature on a time scale of years. Recent MAXI observations have revealed a strange sudden decay feature in some outbursts. It is difficult to explain this decay feature by the simple picture which causes by ordinary mechanisms known in NS-LMXB such as a state transition, a propeller effect and a brink due to disk irradiation (Powell et al. 2007). Therefore, we introduced new type of instability of the accretion disk in relation to stellar wind stripping effect (Asai et al. 2014) which may be common to a system consisting of a compact star and an ordinary massive star.

  11. Evolutionary constraints on the masses of the components of HDE 226868/Cyg X-1 binary system

    NASA Astrophysics Data System (ADS)

    Ziólkowski, J.

    I repeat, using the present day data, Paczyński's analysis of the lower limits to the masses of the components of HDE 226868/Cyg X-1 binary system. The analysis is model independent and based only on uncontestable observational facts. I find that for the most likely distance to the system (d = 2.15 ± 0.07 kpc; [2]) the masses of the optical and compact component must be greater than ~ 28 Msolar and ~ 8 Msolar, respectively. I discuss then the evolutionary status of HDE 226868 and argue that it must be a a core hydrogen burning configuration. Using the simplified evolutionary models of the optical component, I find that its mass must be greater than ~ 28 Msolar (the incidental coincidence with the independently obtained limit, quoted above). Even if the distance to the system was as small as d = 1.8 kpc (the smallest value quoted in the literature), then still the optical component should be more massive than ~ 24 Msolar. I find also that to avoid HDE 226868 being underluminous for its mass, the distance to the system must be smaller than ~ 2.7 kpc. Altogether, my analysis indicates that the mass of HDE 226868 is probably in the range 30 div 40 Msolar and the initial mass of its progenitor was probably 45 div 55 Msolar. The mass of the compact component is probably in the range 15 div 17 Msolar. These results are fully consistent with the values Mopt ≈ 33 Msolar and Mx ≈ 16 Msolar, obtained by Gies and Bolton from the essentially distance independent (but model dependent) analysis.

  12. The binary systems IC 10 X-1 and NGC 300 X-1: Accretion of matter from an intense Wolf-Rayet stellar wind onto a black hole

    NASA Astrophysics Data System (ADS)

    Tutukov, A. V.; Fedorova, A. V.

    2016-01-01

    The current evolutionary stage of the binary systems IC 10 X-1 and NGC 300 X-1, which contain a massive black hole and a Wolf-Rayet star with a strong stellar wind that does not fill its Roche lobe, is considered. The high X-ray luminosity and X-ray properties testify to the presence of accretion disks in these systems. The consistency of the conditions for the existence of such a disk and the possibility of reproducing the observed X-ray luminosity in the framework of the Bondi-Hoyle-Littleton theory for a spherically symmetric stellar wind is analyzed. A brief review of information about the mass-loss rates of Wolf-Rayet stars and the speeds of their stellar winds is given. The evolution of these systems at the current stage is computed. Estimates made using the derived parameters show that it is not possible to achieve consistency, since the conditions for the existence of an accretion disk require that the speed of the Wolf-Rayetwind be appreciably lower than is required to reproduce the observedX-ray luminosity. Several explanations of this situation are possible: (1) the real pattern of the motion of the stellar-wind material in the binary is substantially more complex than is assumed in the Bondi-Hoyle-Littleton theory, changing the conditions for the formation of an accretion disk and influencing the accretion rate onto the black hole; (2) some of the accreting material leaves the accretor due to X-ray heating; (3) the accretion efficiency in these systems is nearly an order of magnitude lower than in the case of accretion through a thin disk onto a non-rotating black hole; (4) the intensity of the Wolf-Rayet wind is one to two orders of magnitude lower than has been suggested by modern studies.

  13. X-ray Studies of the Black Hole Binary Cygnus X-1 with Suzaku

    NASA Astrophysics Data System (ADS)

    Yamada, Shin'ya

    2011-03-01

    In order to study X-ray properties of black hole binaries in so-called Low/Hard state, we analyzed 0.5--300 keV data of Cyg X-1, taken with the X-ray Imaging Spectrometer and the Hard X-ray Detector onboard the X-ray satellite Suzaku. The data were acquired on 25 occasions from 2005 to 2009, with a total exposure of ~450 ks. The source was in the Low/Hard state throughout, and the 0.5-300 keV luminosity changed by a factor of 4, corresponding to 2-10% of the Eddington limit for a 10 Mo black hole. Among the 25 data sets, the first one was already analyzed by Makishima et al. (2008), who successfully reproduced the wide-band spectrum by a linear combination of an emission from a standard accretion disk, soft and hard Comptonization continua, and reprocessed features. Given this, we analyzed the 25 data sets for intensity-related spectral changes, on three different time scales using different analysis methods. One is the source behavior on time scales of days to months, studied via direct comparison among the 25 spectra which are averaged over individual observations. Another is spectral changes on time scales of 1-2 seconds, revealed through ``intensity-sorted spectroscopy''. The other is spectral changes on time scales down to ~0.1 seconds, conducted using ``shot analysis" technique which was originally developed by Negoro et al. (1997) with Ginga. These studies partially incorporated spectral fitting in terms of a thermal Comptonization model. We payed great attention to instrumental problems caused by the source brightness, and occasional ``dipping" episodes which affects the Cyg X-1 spectrum at low energies. The shot analysis incorporated a small fraction of XIS data that were taken in the P-sum mode with a time resolution of 7.8 msec. Through these consistent analyses of all the 25 data sets, we found that a significant soft X-ray excess develops as the source gets brighter. Comparing results from the different time scales, the soft excess was further

  14. Absorption Dips and QPOs in the Eccentric Neutron-star Binary Circinus X-1

    NASA Astrophysics Data System (ADS)

    Shirey, R. E.; Bradt, H. V.; Levine, A. M.; Morgan, E. H.

    1998-12-01

    We have carried out a study of the spectral and temporal X-ray variability of Circinus X-1 through extensive RXTE observations. Dramatic spectral evolution associated with intensity dips is well-fit by variable and at times heavy absorption of a bright component, plus an underlying faint component. An iron emission line at 6.4--6.6 keV present during dips maintains a constant absolute flux level outside the dips as well, indicating that the line is associated with the faint component. These results are consistent with a model in which the faint component is due to scattering of the bright component, with the addition of an iron line due to fluorescence. We show that variability not attributable to absorption dips is related to the spectral/intensity states of the ``Z source'' class of low-mass X-ray binaries (LMXBs), namely motion along (or shifts of) the horizontal, normal, and flaring branches of the ``Z'' track in color-color and hardness-intensity diagrams. On the horizontal branch, quasi-periodic oscillations (QPOs) in the X-ray intensity shift in frequency from 1.3 to 35 Hz. On the normal branch, a different QPO occurs at about 4 Hz. On the flaring branch only strong aperiodic variability occurs. Tight correlations exist between the HBO frequency, the cutoff frequency and amplitude of flat-topped noise, and the frequency of a broad high-frequency QPO peak occuring at 20--200 Hz. We also found that each branch of the spectral track is associated with a specific type of evolution of the energy spectrum, and we have parameterized the evolution of the spectrum in terms of a two-component model consisting of a multi-temperature ``disk blackbody'' and a higher-temperature isothermal blackbody. We also show that an unusual line- or edge-like feature occurs at about 11 keV in energy spectra from the flaring branch and lower normal branch.

  15. Search for Hard X-Ray Emission from Aquila X-1: High Energy Emission from Gamma-ray Radio Star 2CG 135+1/LSI 61 305

    NASA Technical Reports Server (NTRS)

    Tavani, Marco

    1998-01-01

    Several investigations supported by these CCRO grant were completed or are close to completion. The study of EGRET data for the unidentified source 2CG 135+01 was very fruitful. We discovered transient gamma-ray emission by combining several data obtained since 1994 through 1997. It is the first time that time variable emission is established for this enigmatic source, and clearly an interpretation in terms of an isolated radio pulsar (Geminga-like) is disfavored now. Our preferred model is a Galactic source, probably an energetic pulsar (such as PSR129-63) in a binary system producing gamma-rays because of pulsar wind/mass outflow interaction. We also accumulated may data concerning the radio source LSI 61 303, the possible counterpart of 2CG 135+01. We show that a possible anti-correlation between radio and gamma-ray emission exists. This anticorrelation is evident only in the energy range above 100 MeV, as demonstrated by the lack of it obtained from OSSE data. If confirmed, this anti-correlation would prove to be very important for the interpretation of the hundreds of unidentified gamma-ray sources currently discovered by EGRET near the Galactic plane, and would point to a new class of sources in addition to AGNs and isolated pulsars. We also completed the analysis of several time variable gamma-ray sources near the Galactic plane, with the discussion of evidence for transient emission from 2EG J1813-12 and 2EG J1828+01. We completed several investigations regarding gamma-ray bursts (GRBs), including the study of the brightness distribution for different spectral/duration GRB sub-classes, an investigation of acceleration processes and their consequences for GRB afterglow emission [61, the application of the synchrotron shock model of GRBs to X-ray energies.

  16. Combining Fits of The Optical Photometry and X-ray Spectra of the Low Mass X-ray Binary V1408 Aquilae.

    NASA Astrophysics Data System (ADS)

    Gomez, Sebastian; Mason, Paul A.; Robinson, Edward L.

    2015-01-01

    V1408 Aquilae is a binary system with a black hole primary accreting matter from a low mass secondary. We observed the system at the McDonald Observatory and collected 126 hours of high speed optical photometry on the source. We modeled the optical light curve using the XRbinary light curve synthesis software. The best fits to the optical light curve seem to suggest that the primary is a low mass black hole, however we cannot exclude some high mass solutions. Our models slightly favor a 3 solar mass primary at an inclination of about 13 degrees. In order to further constrain these parameters, and verify their validity we compared the fits of the optical light curve to fits to the X-ray spectra of the source. Using data from the Chandra Transmission Grating Catalog and Archive and the ISIS software analysis package we modeled the spectra of the source with a multi-temperature blackbody for a relativistic accretion disk around a spinning black hole and an additional photon power law component. The fits to the optical lightcurve and X-ray spectra are in agreement, from this we conclude that the case for V1408 Aql to be at a low inclination and harbor a low mass black hole is plausible.

  17. Tuning into Scorpius X-1: adapting a continuous gravitational-wave search for a known binary system

    NASA Astrophysics Data System (ADS)

    Meadors, Grant David; Goetz, Evan; Riles, Keith

    2016-05-01

    We describe how the TwoSpect data analysis method for continuous gravitational waves (GWs) has been tuned for directed sources such as the low-mass X-ray binary (LMXB), Scorpius X-1 (Sco X-1). A comparison of five search algorithms generated simulations of the orbital and GW parameters of Sco X-1. Whereas that comparison focused on relative performance, here the simulations help quantify the sensitivity enhancement and parameter estimation abilities of this directed method, derived from an all-sky search for unknown sources, using doubly Fourier-transformed data. Sensitivity is shown to be enhanced when the source sky location and period are known, because we can run a fully templated search, bypassing the all-sky hierarchical stage using an incoherent harmonic sum. The GW strain and frequency, as well as the projected semi-major axis of the binary system, are recovered and uncertainty estimated, for simulated signals that are detected. Upper limits for GW strain are set for undetected signals. Applications to future GW observatory data are discussed. Robust against spin-wandering and computationally tractable despite an unknown frequency, this directed search is an important new tool for finding gravitational signals from LMXBs.

  18. Polarization in massive X-ray binaries. I - A low-inclination model for Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Friend, D. B.; Cassinelli, J. P.

    1986-01-01

    The possibility that variable linear polarization in massive X-ray binaries is produced by electron scattering in an asymmetric stellar wind is investigated. The stellar wind is asymmetric because of the gravitational field of the secondary (X-ray source). The degree of asymmetry and the magnitude of the linear polarization are controlled by the degree to which the primary star fills its Roche lobe. For the well-observed X-ray binary Cyg X-1, the present model can produce the correct magnitude for the polarization. Provided that the inclination of the system is less than about 20 deg, the present model should also predict the correct phase dependence of the polarization. Modifications to the model are described which would enable it to apply to systems with higher inclination.

  19. Circinus X-1: a Laboratory for Studying the Accretion Phenomenon in Compact Binary X-Ray Sources. Ph.D. Thesis - Maryland Univ.

    NASA Technical Reports Server (NTRS)

    Robinson-Saba, J. L.

    1983-01-01

    Observations of the binary X-ray source Circinus X-1 provide samples of a range of spectral and temporal behavior whose variety is thought to reflect a broad continuum of accretion conditions in an eccentric binary system. The data support an identification of three or more X-ray spectral components, probably associated with distinct emission regions.

  20. How Massive are the Heaviest Black Holes in X-ray Binaries? Exploring IC 10 X-1 and its Kind.

    NASA Astrophysics Data System (ADS)

    Laycock, Silas; Maccarone, Tom; Steiner, James F.; Christodoulou, Dimitris; Yang, Jun; Binder, Breanna A.; Cappallo, Rigel

    2016-01-01

    Black hole X-ray binaries represent a unique probe of stellar evolution and the most extreme physical conditions found in nature. The X-ray binary IC 10 X-1 occupies an important niche as a link between BH-XRBs and Ultra Luminous X-ray Sources (ULX) due to its intermediate luminosity (10^38 erg/s), and role as a central exemplar of the association of between low metallicity galaxies and maximum BH mass.The most secure and direct dynamical evidence for any BH mass comes from the radial velocity (RV) curve coupled with eclipse timing measurements. We phase-connected X-ray timing data accumulated over a decade with Chandra/XMM, with the optical RV curve, revealing a surprizing simultenaity of mid X-ray eclipse and the maximum blueshift velocity of He II emission lines. Our interpretation is that the optical emission lines originate in a shadowed sector of the WR star's stellar wind which escapes X-ray ionization by the compact object. The RV shifts are therefore a projection effect of the stellar wind, and unrelated to the system's mass function which becomes completely unknown. Chandra, XMM and NuStar datasets present a complex picture of radiative transfer through a photo-ionized wind. A search for the orbital period derivative (P-dot) by X-ray timing offers additonal insights, and we present a simulation for the feasibility of constraining P-dot via optical means.This is a substantial change to our understanding of IC 10 X-1, and with similar results reported for its "near twin" NGC 300 X-1, adds new a dimension to the facinating question of the maximum mass for stellar BHs.

  1. Constraining the properties of neutron star crusts with the transient low-mass X-ray binary Aql X-1

    NASA Astrophysics Data System (ADS)

    Waterhouse, A. C.; Degenaar, N.; Wijnands, R.; Brown, E. F.; Miller, J. M.; Altamirano, D.; Linares, M.

    2016-03-01

    Aql X-1 is a prolific transient neutron star low-mass X-ray binary that exhibits an accretion outburst approximately once every year. Whether the thermal X-rays detected in intervening quiescent episodes are the result of cooling of the neutron star or due to continued low-level accretion remains unclear. In this work, we use Swift data obtained after the long and bright 2011 and 2013 outbursts, as well as the short and faint 2015 outburst, to investigate the hypothesis that cooling of the accretion-heated neutron star crust dominates the quiescent thermal emission in Aql X-1. We demonstrate that the X-ray light curves and measured neutron star surface temperatures are consistent with the expectations of the crust cooling paradigm. By using a thermal evolution code, we find that ≃1.2-3.2 MeV nucleon-1 of shallow heat release describes the observational data well, depending on the assumed mass-accretion rate and temperature of the stellar core. We find no evidence for varying strengths of this shallow heating after different outbursts, but this could be due to limitations of the data. We argue that monitoring Aql X-1 for up to ≃1 yr after future outbursts can be a powerful tool to break model degeneracies and solve open questions about the magnitude, depth, and origin of shallow heating in neutron star crusts.

  2. Directed searches for continuous gravitational waves from binary systems: Parameter-space metrics and optimal Scorpius X-1 sensitivity

    NASA Astrophysics Data System (ADS)

    Leaci, Paola; Prix, Reinhard

    2015-05-01

    We derive simple analytic expressions for the (coherent and semicoherent) phase metrics of continuous-wave sources in low-eccentricity binary systems for the two regimes of long and short segments compared to the orbital period. The resulting expressions correct and extend previous results found in the literature. We present results of extensive Monte Carlo studies comparing metric mismatch predictions against the measured loss of detection statistics for binary parameter offsets. The agreement is generally found to be within ˜10 %- 30 % . For an application of the metric template expressions, we estimate the optimal achievable sensitivity of an Einstein@Home directed search for Scorpius X-1, under the assumption of sufficiently small spin wandering. We find that such a search, using data from the upcoming advanced detectors, would be able to beat the torque-balance level [R. V. Wagoner, Astrophys. J. 278, 345 (1984); L. Bildsten, Astrophys. J. 501, L89 (1998).] up to a frequency of ˜500 - 600 Hz , if orbital eccentricity is well constrained, and up to a frequency of ˜160 - 200 Hz for more conservative assumptions about the uncertainty on orbital eccentricity.

  3. Linking jet emission and X-ray properties in the peculiar neutron star X-ray binary Circinus X-1

    NASA Astrophysics Data System (ADS)

    Soleri, Paolo; Tudose, Valeriu; Fender, Rob; van der Klis, Michiel; Jonker, Peter G.

    2009-10-01

    We present the results of simultaneous X-ray and radio observations of the peculiar Z-type neutron star X-ray binary Cir X-1, observed with the Rossi X-ray Timing Explorer satellite and the Australia Telescope Compact Array in 2000 October and 2002 December. We identify typical Z-source behaviour in the power density spectra as well as characteristic Z patterns drawn in an X-ray hardness-intensity diagram. Power spectra typical of bright atoll sources have also been identified at orbital phases after the periastron passage, while orbital phases before the periastron passage are characterized by power spectra that are typical neither of Z nor of atoll sources. We investigate the coupling between the X-ray and the radio properties, focusing on three orbital phases when an enhancement of the radio flux density has been detected, to test the link between the inflow (X-ray) and the outflow (radio jet) to/from the compact object. In two out of three cases, we associate the presence of the radio jet to a spectral transition in the X-rays, although the transition does not precede the radio flare, as detected in other Z sources. An analogous behaviour has recently been found in the black hole candidate GX 339-4. In the third case, the radio light curve shows a similar shape to the X-ray light curve. We discuss our results in the context of jet models, considering also black hole candidates.

  4. Hercules X-1: Spectral Variability of an X-Ray Pulsar in a Stellar Binary System. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Pravdo, S. H.

    1976-01-01

    A cosmic X-ray spectroscopy experiment onboard the Orbiting Solar Observatory 8 (OSO-8), observed Her x-1 continuously for approximately 8 days. Spectral-temporal correlations of the X-ray emission were obtained. The major results concern observations of: (1) iron band emission, (2) spectral hardening (increase in effective x-ray temperature) within the X-ray pulse, and (3) a transition from an X-ray low state to a high state. The spectrum obtained prior to the high state can be interpreted as reflected emission from a hot coronal gas surrounding an accretion disk, which itself shields the primary X-ray source from the line of sight during the low state. The spectral hardening within the X-ray pulse was indicative of the beaming mechanism at the neutron star surface. The hardest spectrum by pulse phase was identified with the line of sight close to the Her x-1 magnetic dipole axis, and the X-ray pencil beam become harder with decreasing angle between the line of sight and the dipole axis.

  5. On the Nature of the Variability Power Decay towards Soft Spectral States in X-Ray Binaries. Case Study in Cyg X-1

    NASA Technical Reports Server (NTRS)

    Titarchuk, Lev; Shaposhinikov, Nikolai

    2007-01-01

    A characteristic feature of the Fourier Power Density Spectrum (PDS) observed from black hole X-ray binaries in low/hard and intermediate spectral states is a broad band-limited noise, characterized by a constant below some frequency (a "break" frequency) and a power law above this frequency. It has been shown that the variability of this type can be produced by the inward diffusion of the local driving perturbations in a bounded configuration (accretion disk or corona). In the framework of this model, the perturbation diffusion time to is related to the phenomenological break frequency, while the PDS power-law slope above the "break" is determined by the viscosity distribution over the configuration. The perturbation diffusion scenario explains the decay of the power of X-ray variability observed in a number of compact sources (containing black hole and neutron star) during an evolution of theses sources from low/hard to high/soft states. We compare the model predictions with the subset of data from Cyg X-1 collected by the Rossi X-ray Time Explorer (RXTE). Our extensive analysis of the Cyg X-1 PDSs demonstrates that the observed integrated power P(sub x), decreases approximately as a square root of the characteristic frequency of the driving oscillations v(sub dr). The RXTE observations of Cyg X-1 allow us to infer P(sub dr), and t(sub o) as a function of v(sub dr). We also apply the basic parameters of observed PDSs, power-law index and low frequency quasiperiodic oscillations. to infer Reynolds (Re) number from the observations using the method developed in our previous paper. Our analysis shows that Re-number increases from values about 10 in low/hard state to that about 70 during the high/soft state. Subject headings: accretion, accretion disks-black hole physics-stars:individual (Cyg X-1) :radiation mechanisms: nonthermal-physical data and processes

  6. Tomography of X-Ray Binary CYG X-1 Based on the High-Resolution Optical Spectroscopy

    NASA Astrophysics Data System (ADS)

    Karitskaya, E. A.; Agafonov, M. I.; Bochkarev, N. G.; Sharova, O. I.

    2007-08-01

    We used the optical spectra with resolution R=13000 obtained in the course of Cyg~X-1 spectral monitoring over 2003-2004, carried out with the echelle spectrometer of the 2-m telescope of Peak Terskol Observatory (3100 m, Caucasus). The high-precision spectra show clearly the sequence of line profile variations with orbital phases. The Doppler images were reconstructed by an improved Doppler tomography method developed by Agafonov (2004) (radioastronomical approach) on the base of HeII λ4686Å profiles of 2003 ("soft" X-ray state) and of 2004 ("hard" X-ray state). The main features of the reconstruction are: de-convolution in the image space with the introduction of the synthesized beam (equivalent summarized transfer function) and the removal of the distortions on the summarized image (after back projecting) caused by the sidelobes of this beam using CLEAN algorithm. The method is developed specially for a small number of irregularly distributed observations. The Doppler images and Roche lobe model allowed putting a limitation on the black hole to supergiant mass ratio 1/4≤M[X]/M[O]≤1/3. The emission may come from the accretion disk outer regions heated by the hot supergiant emission, from the "hot line" discussed by Kuznetsov et al.(2001), or/and from the accretion stream (focused stellar wind).

  7. A Test of the Nature of the Fe K Line in the Neutron Star Low-mass X-Ray Binary Serpens X-1

    NASA Astrophysics Data System (ADS)

    Chiang, Chia-Ying; Cackett, Edward M.; Miller, Jon M.; Barret, Didier; Fabian, Andy C.; D’Aì, Antonino; Parker, Michael L.; Bhattacharyya, Sudip; Burderi, Luciano; Di Salvo, Tiziana; Egron, Elise; Homan, Jeroen; Iaria, Rosario; Lin, Dacheng; Miller, M. Coleman

    2016-04-01

    Broad Fe K emission lines have been widely observed in the X-ray spectra of black hole systems as well as in neutron star systems. The intrinsically narrow Fe K fluorescent line is generally believed to be part of the reflection spectrum originating in an illuminated accretion disk which is broadened by strong relativistic effects. However, the nature of the lines in neutron star low-mass X-ray binaries (LMXBs) has been a matter of debate. We therefore obtained the longest, high-resolution X-ray spectrum of a neutron star LMXB to date with a 300 ks Chandra High Energy Transmission Grating Spectrometer (HETGS) observation of Serpens X-1. The observation was taken under the “continuous clocking” mode, and thus was free of photon pile-up effects. We carry out a systematic analysis and find that the blurred reflection model fits the Fe line of Serpens X-1 significantly better than a broad Gaussian component does, implying that the relativistic reflection scenario is much preferred. Chandra HETGS also provides a highest spectral resolution view of the Fe K region and we find no strong evidence for additional narrow lines.

  8. TIME-FREQUENCY ANALYSIS OF THE SUPERORBITAL MODULATION OF THE X-RAY BINARY SMC X-1 USING THE HILBERT-HUANG TRANSFORM

    SciTech Connect

    Hu, Chin-Ping; Chou, Yi; Yang, Ting-Chang; Su, Yi-Hao; Wu, Ming-Chya E-mail: yichou@astro.ncu.edu.tw

    2011-10-20

    The high-mass X-ray binary SMC X-1 exhibits a superorbital modulation with a dramatically varying period ranging between {approx}40 days and {approx}60 days. This research studies the time-frequency properties of the superorbital modulation of SMC X-1 based on the observations made by the All-Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE). We analyzed the entire ASM database collected since 1996. The Hilbert-Huang transform (HHT), developed for non-stationary and nonlinear time-series analysis, was adopted to derive the instantaneous superorbital frequency. The resultant Hilbert spectrum is consistent with the dynamic power spectrum as it shows more detailed information in both the time and frequency domains. The RXTE observations show that the superorbital modulation period was mostly between {approx}50 days and {approx}65 days, whereas it changed to {approx}45 days around MJD 50,800 and MJD 54,000. Our analysis further indicates that the instantaneous frequency changed to a timescale of hundreds of days between {approx}MJD 51,500 and {approx}MJD 53,500. Based on the instantaneous phase defined by HHT, we folded the ASM light curve to derive a superorbital profile, from which an asymmetric feature and a low state with barely any X-ray emissions (lasting for {approx}0.3 cycles) were observed. We also calculated the correlation between the mean period and the amplitude of the superorbital modulation. The result is similar to the recently discovered relationship between the superorbital cycle length and the mean X-ray flux for Her X-1.

  9. Determinations of its Absolute Dimensions and Distance by the Analyses of Light and Radial-Velocity Curves of the Contact Binary -I. V417 Aquilae

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Woo; Kim, Chun-Hwey; Lee, Chung-Uk; Oh, Kyu-Dong

    2004-06-01

    New photometric and spectroscopic solutions of W-type overcontact binary V417 Aql were obtained by solving the UBV light curves of Samec et al. (1997) and radial-velocity ones of Lu & Rucinski (1999) with the 2003 version of the Wilson-Devinney binary code. In the light curve synthesis the light of a third-body, which Qian (2003) proposed, was considered and obtained about 2.7%, 2.2%, and 0.4% for U, B, and V bandpasses, respectively. The model with third-light is better fitted to eclipse parts than that with no third-light. Absolute dimensions of V417 Aql are determined from our solution as M1=0.53 M⊙, M2=1.45 M⊙, R1=0.84 R⊙ and R2=1.31 M⊙, and the distance to it is deduced as about 216pc. Our distance is well consistent with that (204pc) derived from Rucinski & Duerbeck's (1997) relation, MV=MV(log P, B-V), but is more distant than that (131±40pc) determined by the Hipparcos trigonometric parallax. The difference may result from the relatively large error of Hipparcos parallax for V417 Aql.

  10. Large-scale environments of binary AGB stars probed by Herschel. I. Morphology statistics and case studies of R Aquarii and W Aquilae

    NASA Astrophysics Data System (ADS)

    Mayer, A.; Jorissen, A.; Kerschbaum, F.; Ottensamer, R.; Nowotny, W.; Cox, N. L. J.; Aringer, B.; Blommaert, J. A. D. L.; Decin, L.; van Eck, S.; Gail, H.-P.; Groenewegen, M. A. T.; Kornfeld, K.; Mecina, M.; Posch, Thomas; Vandenbussche, B.; Waelkens, C.

    2013-01-01

    The Mass loss of Evolved StarS (MESS) sample offers a selection of 78 asymptotic giant branch (AGB) stars and red supergiants (RSGs) observed with the PACS photometer on-board Herschel at 70 μm and 160 μm. For most of these objects, the dusty AGB wind is not spherically symmetric and the wind shape can be subdivided into four classes. In the present paper we concentrate on the influence of a companion on the morphology of the stellar wind. Literature was searched to find binaries in the MESS sample, which were subsequently linked to their wind-morphology class to assert that the binaries are not distributed equally among the classes. In the second part of the paper we concentrate on the circumstellar environment of the two prominent objects R Aqr and W Aql. Each shows a characteristic signature of a companion interaction with the stellar wind. For the symbiotic star R Aqr, PACS revealed two perfectly opposing arms that in part reflect the previously observed ring-shaped nebula in the optical. However, from the far-IR there is evidence that the emitting region is elliptical rather than circular. The outline of the wind of W Aql seems to follow a large Archimedean spiral formed by the orbit of the companion but also shows strong indications of an interaction with the interstellar medium. We investigated the nature of the companion of W Aql and found that the magnitude of the orbital period supports the size of the spiral outline. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  11. L'Aquila verdict quashed

    NASA Astrophysics Data System (ADS)

    Banks, Michael

    2014-12-01

    Six of the seven scientists and engineers who were controversially found guilty of manslaughter for the role that they played in the 2009 L’Aquila earthquake have been cleared after a month-long appeal trial.

  12. The commercial Aquila Launch Vehicle

    NASA Astrophysics Data System (ADS)

    Flittie, Kirk J.; McFarlane, Scott

    1991-06-01

    The American Rocket Company's (AMROC) Aquila Launch Vehicle is a ground-launched, four-stage, all-hybrid propulsion, inertially-guided commercial space booster designed to deliver 2000 pound payloads into low earth orbit. By using AMROC's low-cost hybrid propulsion, the Aquila launch service will provide quick, on-demand, routine access to space; high accuracy orbital placement; and an unprecedented degree of production, ground and flight safety. The first launch of the Aquila will be in early 1995. Aquila utilizes AMROc's unique hybrid propulsion systems consisting of an inert solid polybutadiene fuel and either liquid oxygen or nitrous oxide as oxidizer. A hybrid propulsion system is distinct from all other rocket propulsion systems in that hybrids cannot explode; hybrids offer safe handling, operation and launch pad abort; and hybrids offer start/stop and full throttling capability for trajectory optimization and precise payload placement on orbit. In addition, the exhaust products do not contain hydrogen chlorides which are environmentally degrading.

  13. Long-Term Properties of Accretion Discs in X-ray Binaries. 1; The Variable Third Period in SMC X-1

    NASA Technical Reports Server (NTRS)

    Charles, P. A.; Clarkson, W. I.; Coe, M. J.; Laycock, S.; Tout, M.; Wilson, C.; Six, N. Frank (Technical Monitor)

    2002-01-01

    Long term X-ray monitoring data from the RXTE All Sky Monitor (ASM) reveal that the third (superorbital) period in SMC X-1 is not constant but varies between 40-60 days. A dynamic power spectrum analysis indicates that the third period has been present continuously throughout the five years of ASM observations. This period changed smoothly from 60 days to 45 days and then returned to its former value, on a timescale of approximately 1600 days. During the nearly 4 years of overlap between the CGRO & RXTE missions, the simultaneous BATSE hard X-ray data confirm this variation in SMC X-1. Sources of systematic error and possible artefacts are investigated and found to be incapable of reproducing the results reported here. Our disco cry of such an instability in the superorbital period of SMC X-1 is interpreted in the context of recent theoretical studies of warped, precessing accretion discs. We find that the behaviour of SMC X-1 is consistent with a radiation - driven warping model.

  14. A test of the nature of the Fe K Line in the neutron star low-mass X-ray binary Serpens X-1

    NASA Astrophysics Data System (ADS)

    Chiang, Chia-Ying; Cackett, Edward; Miller, Jon M.; Barret, Didier; Fabian, Andrew C.; D'Ai, Antonino; Parker, Michael; Bhattacharyya, Sudip; Burderi, Luciano; Salvo, Tiziana; Egron, Elise; Homan, Jeroen; Iaria, Rosario; Lin, Dacheng; Miller, M. Coleman

    2016-04-01

    Broad Fe K emission lines have been widely observed in the X-ray spectra of black hole systems, and in neutron star systems as well. The intrinsically narrow Fe K fluorescent line is generally believed to be part of the reflection spectrum originating in an illuminated accretion disk, and broadened by strong relativistic effects. However, the nature of the lines in neutron star LMXBs has been under debate. We therefore obtained the longest, high-resolution X-ray spectrum of a neutron star LMXB to date with a 300 ks Chandra HETGS observation of Serpens X-1. The observation was taken under the "continuous clocking" mode and thus free of photon pile-up effects. We carry out a systematic analysis and find that the blurred reflection model fits the Fe line of Serpens X-1 significantly better than a broad Gaussian component does, implying that the relativistic reflection scenario is much preferred. Chandra HETGS also provides highest spectral resolution view of the Fe K region and we find no strong evidence for additional narrow lines.

  15. The results of X-ray binary Cyg X-1 investigations based on the optical photometry and high-resolution spectroscopy

    NASA Astrophysics Data System (ADS)

    Karitskaya, Eugenia A.

    2007-04-01

    Selected results of multi-year optical photometric and high-resolution spectral observations including obtained in the frame of coordinated CIS countries campaign "Optical Monitoring of Unique Astrophysical Objects" are briefly reviewed. Comparison with ASM/RXTE X-ray data is used. Besides of orbital variations different kinds of flares, dips and so-called precession period 147/294 days were revealed. The observational evidences of instability of matter flowing from one component to another have been appeared. Cross-correlation analysis yielded the lags between the optical and X-ray (2-10 keV) long time variations with the delaying of the last ones on 7d in 1996 and 12d in 1997-1998. The very same lags were revealed between the optical and X-ray flares in these years. So the characteristic time of the matter transfer through the accretion disk was about 7 days in Summer and Autumn 1996 and about 12 days in 1997-1998 and alpha-model of accretion disc does not work. Optical spectral line profile variations were found during X-ray flare. The comparison of observed and non-LTE model profiles for HI, HeI and MgII is given taking into account tidal distortion of Cyg X-1 optical component and its illumination by X-ray emission of secondary one. We set limits on the optical component main characteristics T[eff] = 30400±500K, log g = 3.31±0.07 and overabundance of He and Mg: [He/H] = 0.43±0.06 dex, [Mg/H] = 0.75±0.15 dex by using spectra of 2003-2004. The Doppler images were reconstructed by an improved Doppler tomography method on the base of 9 HeIIλ4686Å profiles of 2003 ("soft" X-ray state) and 6 profiles of 2004 ("hard" X-ray state). It allowed putting a limitation on the black hole to supergiant mass ratio 1/4 ≤ M[X]/M[O] ≤ 1/3. The photometric and spectral variations point to the supergiant parameters changes on the time scale of tens of years. Line profile non-LTE simulations lead to the conclusion that the star radius has grown about 1-4% from 1997 to 2003

  16. Measuring the stellar wind parameters in IGR J17544-2619 and Vela X-1 constrains the accretion physics in supergiant fast X-ray transient and classical supergiant X-ray binaries

    NASA Astrophysics Data System (ADS)

    Giménez-García, A.; Shenar, T.; Torrejón, J. M.; Oskinova, L.; Martínez-Núñez, S.; Hamann, W.-R.; Rodes-Roca, J. J.; González-Galán, A.; Alonso-Santiago, J.; González-Fernández, C.; Bernabeu, G.; Sander, A.

    2016-06-01

    Context. Classical supergiant X-ray binaries (SGXBs) and supergiant fast X-ray transients (SFXTs) are two types of high-mass X-ray binaries (HMXBs) that present similar donors but, at the same time, show very different behavior in the X-rays. The reason for this dichotomy of wind-fed HMXBs is still a matter of debate. Among the several explanations that have been proposed, some of them invoke specific stellar wind properties of the donor stars. Only dedicated empiric analysis of the donors' stellar wind can provide the required information to accomplish an adequate test of these theories. However, such analyses are scarce. Aims: To close this gap, we perform a comparative analysis of the optical companion in two important systems: IGR J17544-2619 (SFXT) and Vela X-1 (SGXB). We analyze the spectra of each star in detail and derive their stellar and wind properties. As a next step, we compare the wind parameters, giving us an excellent chance of recognizing key differences between donor winds in SFXTs and SGXBs. Methods: We use archival infrared, optical and ultraviolet observations, and analyze them with the non-local thermodynamic equilibrium (NLTE) Potsdam Wolf-Rayet model atmosphere code. We derive the physical properties of the stars and their stellar winds, accounting for the influence of X-rays on the stellar winds. Results: We find that the stellar parameters derived from the analysis generally agree well with the spectral types of the two donors: O9I (IGR J17544-2619) and B0.5Iae (Vela X-1). The distance to the sources have been revised and also agree well with the estimations already available in the literature. In IGR J17544-2619 we are able to narrow the uncertainty to d = 3.0 ± 0.2 kpc. From the stellar radius of the donor and its X-ray behavior, the eccentricity of IGR J17544-2619 is constrained to e< 0.25. The derived chemical abundances point to certain mixing during the lifetime of the donors. An important difference between the stellar winds of the

  17. Simultaneous X-ray and optical observations of the flaring X-ray source, Aquila A-1

    NASA Technical Reports Server (NTRS)

    Bowyer, C. S.; Charles, P. A.

    1979-01-01

    During the summer of 1978 the recurrent transient X-ray source, Aquila X-1, underwent its first major outburst in two years. The results of extensive observations at X-ray and optical wavelengths throughout this event, which lasted for approximately two months are presented. The peak X-ray luminosity was approximately 1.3 times that of the Crab and exhibited spectral dependent flickering on timescales approximately 5 minutes. The observations are interpreted in terms of a standard accretion disk model withparticular emphasis on the similarities to Sco X-1 and other dward X-ray systems, although the transient nature of the system remains unexplained. It was found that Aquila X-1 can be described adequately by the semi-detached Roche lobe model and yields a mass ratio of less than or approximate to 3.5.

  18. The L'Aquila trial

    NASA Astrophysics Data System (ADS)

    Amato, Alessandro; Cocco, Massimo; Cultrera, Giovanna; Galadini, Fabrizio; Margheriti, Lucia; Nostro, Concetta; Pantosti, Daniela

    2013-04-01

    The first step of the trial in L'Aquila (Italy) ended with a conviction of a group of seven experts to 6 years of jail and several million euros refund for the families of the people who died during the Mw 6.3 earthquake on April 6, 2009. This verdict has a tremendous impact on the scientific community as well as on the way in which scientists deliver their expert opinions to decision makers and society. In this presentation, we describe the role of scientists in charge of releasing authoritative information concerning earthquakes and seismic hazard and the conditions that led to the verdict, in order to discuss whether this trial represented a prosecution to science, and if errors were made in communicating the risk. Documents, articles and comments about the trial are collected in the web site http://processoaquila.wordpress.com/. We will first summarize what was the knowledge about the seismic hazard of the region and the vulnerability of L'Aquila before the meeting of the National Commission for Forecasting and Predicting Great Risks (CGR) held 6 days before the main shock. The basic point of the accusation is that the CGR suggested that no strong earthquake would have occurred (which of course was never mentioned by any seismologist participating to the meeting). This message would have convinced the victims to stay at home, instead of moving out after the M3.9 and M3.5 earthquakes few hours before the mainshock. We will describe how the available scientific information was passed to the national and local authorities, and in general how the Italian scientific Institution in charge of seismic monitoring and research (INGV), the Civil Protection Department (DPC) and the CGR should interact according to the law. As far as the communication and outreach to the public, the scientific Institutions as INGV have the duty to communicate scientific information. Instead, the risk management and the definition of actions for risk reduction is in charge of Civil

  19. The close environment of high-mass X-ray binaries at high angular resolution. I. VLTI/AMBER and VLTI/PIONIER near-infrared interferometric observations of Vela X-1

    NASA Astrophysics Data System (ADS)

    Choquet, É.; Kervella, P.; Le Bouquin, J.-B.; Mérand, A.; Berger, J.-P.; Haubois, X.; Perrin, G.; Petrucci, P.-O.; Lazareff, B.; Pott, J.-U.

    2014-01-01

    Context. Recent improvements in the sensitivity and spectral resolution of X-ray observations have led to a better understanding of the properties of matter in the near vicinity of high-mass X-ray binaries (HMXB) hosting a supergiant star and a compact object. However, the geometry and physical properties of their environments on larger scales (up to a few stellar radii) are currently only predicted by simulations but have never been directly observed. Aims: We aim to explore the environment of Vela X-1 at a few stellar radii (R⋆) of the supergiant using spatially resolved observations in the near-infrared, and to study its dynamical evolution along the nine-day orbital period of the system. Methods: We observed Vela X-1 in 2010 and 2012 using near-infrared long baseline interferometry at the Very Large Telescope Interferometer (VLTI), respectively with the AMBER instrument in the K band (medium spectral resolution), and the PIONIER instrument in the H band (low spectral resolution). The PIONIER observations span one orbital period to monitor possible evolutions in the geometry of the system. Results: We resolved a structure of 8 ± 3 R⋆ from the AMBER K-band observations, and 2.0-1.2+0.7R* from the PIONIER H-band data. From the closure phase observable, we found that the circumstellar environment of Vela X-1 is symmetrical in the near-infrared. We observed comparable interferometric measurements between the continuum and the spectral lines in the K band, meaning that both emissions originate from the same forming region. From the monitoring of the system over one period in the H band in 2012, we found the signal to be constant with the orbital phase within the error bars. Conclusions: We propose three possible scenarios for this discrepancy between the two measurements: 1) there is a strong temperature gradient in the supergiant wind, leading to a hot component that is much more compact than the cool part of the wind observed in the K band; 2) we observed a

  20. THE TRIGONOMETRIC PARALLAX OF CYGNUS X-1

    SciTech Connect

    Reid, Mark J.; McClintock, Jeffrey E.; Narayan, Ramesh; Gou Lijun; Remillard, Ronald A.; Orosz, Jerome A.

    2011-12-01

    We report a direct and accurate measurement of the distance to the X-ray binary Cygnus X-1, which contains the first black hole to be discovered. The distance of 1.86{sup +0.12}{sub -0.11} kpc was obtained from a trigonometric parallax measurement using the Very Long Baseline Array. The position measurements are also sensitive to the 5.6 day binary orbit and we determine the orbit to be clockwise on the sky. We also measured the proper motion of Cygnus X-1 which, when coupled to the distance and Doppler shift, gives the three-dimensional space motion of the system. When corrected for differential Galactic rotation, the non-circular (peculiar) motion of the binary is only about 21 km s{sup -1}, indicating that the binary did not experience a large 'kick' at formation.

  1. X-1 in flight

    NASA Technical Reports Server (NTRS)

    1947-01-01

    The Bell Aircraft Corporation X-1-1 (#46-062) in flight. The shock wave pattern in the exhaust plume is visible. The X-1 series aircraft were air-launched from a modified Boeing B-29 or a B-50 Superfortress bombers. The X-1-1 was painted a bright orange by Bell Aircraft. It was thought that the aircraft would be more visable to those doing the tracking during a flight. When NACA received the airplanes they were painted white, which was an easier color to find in the skies over Muroc Air Field in California. This particular craft was nicknamed 'Glamorous Glennis' by Chuck Yeager in honor of his wife, and is now on permanent display in the Smithsonian Institution's National Air and Space Museum in Washington, DC. There were five versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all

  2. The North Polar Spur and Aquila Rift

    NASA Astrophysics Data System (ADS)

    Sofue, Yoshiaki

    2015-03-01

    Soft X-ray intensity at 0.89 keV along the North Polar Spur (NPS) is shown to follow the extinction law due to the interstellar gas in the Aquila Rift by analysing the ROSAT archival data, which proves that the NPS is located behind the rift. The Aquila-Serpens molecular clouds, where the X-ray optical depth exceeds unity, are shown to have a mean LSR velocity of v = 7.33 ± 1.94 km s-1, corresponding to a kinematic distance of r = 0.642 ± 0.174 kpc. Assuming a shell structure, a lower limit of the distance to NPS is derived to be 1.01 ± 0.25 kpc, with the shell centre being located farther than 1.1 kpc. Based on the distance estimation, we argue that the NPS is a Galactic halo object.

  3. The Bright Symbiotic Mira EF Aquilae

    NASA Astrophysics Data System (ADS)

    Margon, Bruce; Prochaska, J. Xavier; Tejos, Nicolas; Monroe, TalaWanda

    2016-02-01

    An incidental spectrum of the poorly studied long-period variable EF Aquilae shows [O III] emission indicative of a symbiotic star. Strong GALEX detections in the UV reinforce this classification, providing overt evidence for the presence of the hot subluminous companion. Recent compilations of the photometric behavior strongly suggest that the cool component is a Mira variable. Thus EF Aql appears to be a member of the rare symbiotic Mira subgroup.

  4. X1 Exoskeleton

    NASA Video Gallery

    NASA's Ironman-Like Exoskeleton Could Give Astronauts, Paraplegics Improved Mobility and Strength. While NASA's X1 robotic exoskeleton can't do what you see in the movies, the latest robotic, space...

  5. Binary stars.

    PubMed

    Paczynacuteski, B

    1984-07-20

    Most stars in the solar neighborhood are either double or multiple systems. They provide a unique opportunity to measure stellar masses and radii and to study many interesting and important phenomena. The best candidates for black holes are compact massive components of two x-ray binaries: Cygnus X-1 and LMC X-3. The binary radio pulsar PSR 1913 + 16 provides the best available evidence for gravitational radiation. Accretion disks and jets observed in close binaries offer a very good testing ground for models of active galactic nuclei and quasars. PMID:17749544

  6. V803 Aquilae: A newborn W Ursae Majoris Siamese twin?

    NASA Technical Reports Server (NTRS)

    Samec, Ronald G.; Su, Wen; Dewitt, Jason R.

    1993-01-01

    A complete photometric analysis of BVRI photometry of the physically compact, eclipsing binary V803 Aquilae is presented. Six mean epochs of minimum light were determined from observations covering three primary and three secondary eclipses. A period study covering 54 years of observation or nearly 77,000 orbital revolutions reveals three distinct eras of constant period with two major period jumps of +0.1 s and -0.3 s. The light curves shows that the primary and secondary eclipse depths are identical in V, and are nearly identical in B, R, and I, indicating that the components have nearly the same temperatures. Standard magnitudes were determined and a reddening estimate was made. A simultaneous solution of the four light curves was computed using the Wilson-Devinney synthetic light-curve code. The solution indicates that the system consists of twin approximately K4 stars in shallow contact with a fill-out of approximately 8%. A mass ratio of 1.000 was computed with a negligible temperature difference of only 6 K. Thus, based on our purely photometric solution, V803 Aql is made up of 'Siamese' (contact) twin components. Theory would indicate that the twins have just recently come into contact, and the lack of other equal-mass W Ursae Majoris systems would indicate that it is in a very transient or unusual state.

  7. V803 Aquilae: A newborn W Ursae Majoris Siamese twin?

    NASA Astrophysics Data System (ADS)

    Samec, Ronald G.; Su, Wen; Dewitt, Jason R.

    1993-12-01

    A complete photometric analysis of BVRI photometry of the physically compact, eclipsing binary V803 Aquilae is presented. Six mean epochs of minimum light were determined from observations covering three primary and three secondary eclipses. A period study covering 54 years of observation or nearly 77,000 orbital revolutions reveals three distinct eras of constant period with two major period jumps of +0.1 s and -0.3 s. The light curves shows that the primary and secondary eclipse depths are identical in V, and are nearly identical in B, R, and I, indicating that the components have nearly the same temperatures. Standard magnitudes were determined and a reddening estimate was made. A simultaneous solution of the four light curves was computed using the Wilson-Devinney synthetic light-curve code. The solution indicates that the system consists of twin approximately K4 stars in shallow contact with a fill-out of approximately 8%. A mass ratio of 1.000 was computed with a negligible temperature difference of only 6 K. Thus, based on our purely photometric solution, V803 Aql is made up of 'Siamese' (contact) twin components. Theory would indicate that the twins have just recently come into contact, and the lack of other equal-mass W Ursae Majoris systems would indicate that it is in a very transient or unusual state.

  8. Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The brightest cosmic x-ray source in the constellation of Scorpius and the first cosmic x-ray source to be discovered. Detected for the first time in 1962 by instrumentation carried to an altitude of 225 km by an Aerobee rocket, Scorpius X-1 is, apart from occasional transient sources, the brightest cosmic source of x-radiation in the sky....

  9. Scientists face trial over L'Aquila quake

    NASA Astrophysics Data System (ADS)

    Cartlidge, Edwin

    2010-07-01

    Seven scientists and technicians who were called upon to assess seismic activity ahead of the devastating earthquake that struck L'Aquila in the central Italian region of Abruzzo last year are being investigated for gross negligent manslaughter.

  10. Diffuse Radiation from the Aquila Rift

    NASA Astrophysics Data System (ADS)

    Jyothy, S. N.; Murthy, Jayant; Karuppath, Narayanankutty; Sujatha, N. V.

    2015-12-01

    We present an analysis of the diffuse ultraviolet (UV) background in a low latitude region near the Aquila Rift based on observations made by the Galaxy Evolution Explorer (GALEX). The UV background is at a level of about 2000 ph cm-2 s-1 sr-1 Å-1 with no correlation with either the Galactic latitude or the 100 μm infrared (IR) emission. Rather, the UV emission falls off with distance from the bright B2 star HIP 88149, which is in the centre of the field. We have used a Monte Carlo model to derive an albedo of 0.6-0.7 in the UV with a phase function asymmetry factor (g) of 0.2-0.4. The value for the albedo is dependent on the dust distribution while g is determined by the extent of the halo.

  11. Contact binary stars

    NASA Astrophysics Data System (ADS)

    Mochnacki, S. W.

    1981-04-01

    Densities, corrected primary colors, minimum periods, inferred masses, luminosities, and specific angular momenta are computed from data on 37 W Ursae Majoris systems. A-type systems, having lower densities and angular momenta than the W-type systems, are shown to be evolved, and a new class of contact binary is identified, the OO Aquilae systems, whose members have evolved into contact. Evolutionary grids based on the contact condition agree with observation, except in that the evolved A-type systems have lost more angular momentum than predicted by gravitational radiation alone. This is accounted for by stellar wind magnetic braking, which is shown to be effective on a shorter time scale and to be important in other kinds of binaries containing a cool, tidally coupled component.

  12. X-ray binaries

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Satellite X-ray experiments and ground-based programs aimed at observation of X-ray binaries are discussed. Experiments aboard OAO-3, OSO-8, Ariel 5, Uhuru, and Skylab are included along with rocket and ground-based observations. Major topics covered are: Her X-1, Cyg X-3, Cen X-3, Cyg X-1, the transient source A0620-00, other possible X-ray binaries, and plans and prospects for future observational programs.

  13. Detection of Interstellar C3 in the Spectra of ζ Ophiuchi, 20 Aquilae, and ζ Persei

    NASA Astrophysics Data System (ADS)

    Bohlender, D. A.; Walker, G. A. H.; Maier, J. P.; Lakin, N. M.

    2000-12-01

    The smallest polyatomic carbon chain, C3, has been identified in interstellar clouds (Av ~1 mag) towards ζ Ophiuchi, 20 Aquilae, and ζ Persei by detection of the origin band of its A1Π u-X1Σ+g electronic transition, near 4052Å. Individual rotational lines were resolved up to J=30 enabling the rotational level column densities and temperature distributions to be determined. The inferred limits for the total column densities ( ~1 to 2*E12 cm-2) offer a strong incentive to laboratory and astrophysical searches for the longer carbon chains. Concurrent searches for C2+, C2- and C3- were negative but provide sensitive estimates for their maximum column densities.

  14. VLBI observations of a radio flare of Circinus X-1

    NASA Technical Reports Server (NTRS)

    Preston, R. A.; Morabito, D. D.; Wehrle, A. E.; Jauncey, D. L.; Batty, M. J.; Haynes, R. F.; Wright, A. E.; Nicolson, G. D.

    1983-01-01

    VLBI 2.3 GHz observations of a strong radio flare of the binary star system Circinus X-1 indicate a radio source flaring component angular size of 0.0015-0.015 arcsec. This is equivalent to a linear size of 15-150 AU at the 10 kpc distance of Circinus X-1, although interstellar medium scattering may have enlarged the apparent angular source size. Since the radio source quiescent component, observed prior to the flare, had an angular size greater than 0.2 arcsec (equivalent to more than 2000 AU at 10 kpc), the quiescent radio emission comes from a region much larger than that proposed in recent models for Circinus X-1. The quiescent component appears to be variable on a time scale of years, and is probably fueled by the Circinus X-1 binary system.

  15. L'Aquila earthquake verdict yields aftershocks

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2012-11-01

    The 22 October verdict by a court in L'Aquila, Italy, convicting seven Italian earthquake experts of manslaughter for failing to provide an adequate seismic warning to residents prior to a damaging quake in the region continues to send shockwaves through the scientific community. A sampling of the scientific community's concern about the verdict, which is likely to be appealed, included a 25 October joint statement from U.S. National Academy of Sciences president Ralph Cicerone and U.K. Royal Society president Sir Paul Nurse that noted "the difficult task facing scientists in dealing with risk communication and uncertainty." The statement continued, "Much as society and governments would like science to provide simple, clear-cut answers to the problems that we face, it is not always possible. Scientists can, however, gather all the available evidence and offer an analysis of the evidence in light of what they do know. The sensible course is to turn to expert scientists who can provide evidence and advice to the best of their knowledge. They will sometimes be wrong, but we must not allow the desire for perfection to be the enemy of good. That is why we must protest the verdict in Italy. If it becomes a precedent in law, it could lead to a situation in which scientists will be afraid to give expert opinion for fear of prosecution or reprisal. Much government policy and many societal choices rely on good scientific advice and so we must cultivate an environment that allows scientists to contribute what they reasonably can, without being held responsible for forecasts or judgments that they cannot make with confidence."

  16. Testimonies to the L'Aquila earthquake (2009) and to the L'Aquila process

    NASA Astrophysics Data System (ADS)

    Kalenda, Pavel; Nemec, Vaclav

    2014-05-01

    Lot of confusions, misinformation, false solidarity, efforts to misuse geoethics and other unethical activities in favour of the top Italian seismologists responsible for a bad and superficial evaluation of the situation 6 days prior to the earthquake - that is a general characteristics for the whole period of 5 years separating us from the horrible morning of April 6, 2009 in L'Aquila with 309 human victims. The first author of this presentation as a seismologist had unusual opportunity to visit the unfortunate city in April 2009. He got all "first-hand" information that a real scientifically based prediction did exist already for some shocks in the area on March 29 and 30, 2009. The author of the prediction Gianpaolo Giuliani was obliged to stop any public information diffused by means of internet. A new prediction was known to him on March 31 - in the day when the "Commission of Great Risks" offered a public assurance that any immediate earthquake can be practically excluded. In reality the members of the commission completely ignored such a prediction declaring it as a false alarm of "somebody" (even without using the name of Giuliani). The observations by Giuliani were of high quality from the scientific point of view. G. Giuliani predicted L'Aquila earthquake in the professional way - for the first time during many years of observations. The anomalies, which preceded L'Aquila earthquake were detected on many places in Europe in the same time. The question is, what locality would be signed as potential focal area, if G. Giuliani would know the other observations in Europe. The deformation (and other) anomalies are observable before almost all of global M8 earthquakes. Earthquakes are preceded by deformation and are predictable. The testimony of the second author is based on many unfortunate personal experiences with representatives of the INGV Rome and their supporters from India and even Australia. In July 2010, prosecutor Fabio Picuti charged the Commission

  17. Six of the L'Aquila Seven Acquitted in Appeal

    NASA Astrophysics Data System (ADS)

    Rosen, Julia

    2014-11-01

    On 10 November, a panel of judges acquitted the scientists charged with manslaughter in the wake of a deadly earthquake that struck the Italian city of L'Aquila in 2009. Only the former deputy director of Italy's Civil Protection Department, Bernardo De Bernardinis, faces a 2-year sentence, which he may not serve.

  18. X-1A impact site

    NASA Technical Reports Server (NTRS)

    1955-01-01

    A photo taken on 8 August 1955, showing the remains of the Bell X-1A The Bell X-1A (Serial # 48-1384) was designed for aerodynamic stability and air load research. It was delivered to Edwards Air Force Base on 7 January 1953. The aircraft made its first glide flight on 14 February with Bell test pilot Jean 'Skip' Ziegler at the controls. Ziegler also flew the first powered flight in the X-1A on 21 February. Contractor flights in the aircraft continued through April, at which time the X-1A was temporarily grounded for modifications. Flight operations were resumed on 21 November 1953 with Maj. Charles 'Chuck' Yeager at the controls. During a flight on 12 December, Yeager took the X-1A to a record-breaking speed of Mach 2.44 at an altitude of 75,000 feet. He then encountered the unpleasant phenomemon of inertia coupling. The X-1A tumbled out of control, knocking Yeager unconscious briefly before entering an inverted spin. Fortunately Yeager regained his senses and control of the aircraft 60 miles from Edwards at an altitude of 25,000 feet. Shaken, but unharmed, he brought the rocket plane in for a safe landing on Rogers Dry Lake. Next, the X-1A was used for a series of high-altitude missions piloted by Maj. Arthur 'Kit' Murray. Fourteen flights proved necessary to meet the program requirements, with only four being successful. During the test series, Murray set several unofficial world altitude records. The highest (90,440 feet) was set on 26 August 1954. Following completion of the altitude program, the aircraft was turned over to the National Advisory Committee for Aeronautics (NACA). The X-1A underwent more modifications and was returned to flight status in July 1955. The first NACA-sponsored flight, piloted by Joseph A. Walker, took place on 20 July. The second NACA mission was to be the 25th flight of the X-1A. The flight began normally on 8 August 1955, with the X-1A shackled to the underside of a JTB-29A (45-21800) piloted by Stanley Butchart and John 'Jack' Mc

  19. Long-term studies with the Ariel 5 ASM. I - Hercules X-1, Vela X-1, and Centaurus X-3

    NASA Technical Reports Server (NTRS)

    Holt, S. S.; Kaluzienski, L. J.; Boldt, E. A.; Serlemitsos, P. A.

    1979-01-01

    Twelve hundred days of 3-6 keV X-ray data from Her X-1, Vela X-1, and Cen X-3 accumulated with the Ariel 5 All-Sky Monitor are interrogated. The binary periodicities of all three can be clearly observed, as can the 35 day variation of Her X-1, for which we can refine the period to 34.875 plus or minus 0.030 days. No such longer-term periodicity less than 200 days is observed from Vela X-1. The 26.6 days low-state recurrence period for Cen X-3 is not observed, but a 43.0 day candidate periodicity is found which may be consistent with the precession of an accretion disk in that system. The present results are illustrative of the long-term studies which can be performed on approximately 50 sources over a temporal base which will ultimately extend to at least 1800 days.

  20. Mass transfer and magnetic braking in Sco X-1

    NASA Astrophysics Data System (ADS)

    Pavlovskii, K.; Ivanova, N.

    2016-02-01

    Sco X-1 is a low-mass X-ray binary (LMXB) that has one of the most precisely determined set of binary parameters such as the mass accretion rate, companions mass ratio and the orbital period. For this system, as well as for a large fraction of other well-studied LMXBs, the observationally-inferred mass accretion rate is known to strongly exceed the theoretically expected mass transfer (MT) rate. We suggest that this discrepancy can be solved by applying a modified magnetic braking prescription, which accounts for increased wind mass-loss in evolved stars compared to main sequence stars. Using our MT framework based on MESA, we explore a large range of binaries at the onset of the MT. We identify the subset of binaries for which the MT tracks cross the Sco X-1 values for the mass ratio and the orbital period. We confirm that no solution can be found for which the standard magnetic braking can provide the observed accretion rates, while wind-boosted magnetic braking can provide the observed accretion rates for many progenitor binaries that evolve to the observed orbital period and mass ratio.

  1. The Aquila Launch Vehicle - A hybrid propulsion space booster

    NASA Astrophysics Data System (ADS)

    Flittie, Kirk J.; Estey, Paul N.; Kniffen, R. J.

    1991-10-01

    The Aquila Launch Vehicle is the first low-cost hybrid rocket propulsion space booster capable of placing 1450-kg payloads into LEO with high availability and reliability, as well as unprecedented levels of production, ground, and flight operations safety. Since hybrid rockets cannot explode, they may be readily manufactured in light-industrial production facilities. Polar-orbit operations with commercial and government-project payloads are scheduled to begin from Vandenberg AFB in 1995.

  2. A radio nebula associated with Circinus X-1

    NASA Technical Reports Server (NTRS)

    Haynes, R. F.; Komesaroff, M. M.; Jauncey, D. L.; Caswell, J. L.; Milne, D. K.; Kesteven, M. J.; Wellington, K. J.; Preston, R. A.

    1986-01-01

    An investigation of the variable source Circinus X-1 is reported that reveals that this eccentric double-star system is embedded in a nebula of steady radio emission extending over several parsecs, orders of magnitude larger than the binary stellar system responsible for the fluctuating component of emission. This is in marked constrast to most X-ray binaries, where an envelope of radio emission in conspicuously absent. There are difficulties in explaining the emission, but analogies with SS433 and the Crab nebula suggest possible models.

  3. Shakemaps of the L'Aquila main shock

    NASA Astrophysics Data System (ADS)

    Faenza, L.; Lauciani, V.; Michelini, A.

    2009-12-01

    This work addresses the determination of the shakemap of the l’Aquila, M6.3 April 6, 2009, main shock. Since 2006 and as part of national projects funded by the Italian Civil Protection and by the EU SAFER project, INGV has been determining shakemaps for M3.0+ using the USGS-ShakeMap software package and a fully automatic procedure, based on manually revised location and magnitude. This work summarizes how the shakemaps of the main shocks have been obtained. Focus of the presentation is on the importance that the data and the extent of the finite fault have in the determination of faithful ground motion maps. For the L'Aquila main shock, we have found that the data alone are not sufficient to replicate the observed ground motion in parts of the strongly affected areas. In particular, since the station coverage toward the SE where the earthquake rupture propagated is scantier, prompt availability of a rupture fault model would have been important to better describe the level of strong ground motion throughout the affected area. We present an overview of the performance of the INGV real time system during the L’Aquila main shock - the first time that INGV provides real time information to Civil Protetion during a seismic crisis. Finally, we show a comparison between the intensities determined from the strong ground motion and those obtained from the macroseismic survey.

  4. Discovery of iron line emission in the Hercules X-1 low state spectrum with HEAO-1

    NASA Technical Reports Server (NTRS)

    Pravdo, S. H.; Boldt, E. A.; Holt, S. S.; Rothschild, R. E.; Serlemitsos, P. J.

    1978-01-01

    The line energy, equivalent width, binary phase dependence, and intrinsic width of the iron line emission feature observed in the low state sepctrum of Hercules X-1 are examined. Deductions are made concerning secondary X-ray emission from this binary system.

  5. EVN detection of Aql X-1 in outburst

    NASA Astrophysics Data System (ADS)

    Tudose, V.; Paragi, Z.; Miller-Jones, J.; Garrett, M.; Fender, R.; Rushton, A.; Spencer, R.

    2009-11-01

    The X-ray binary Aql X-1 has been in outburst in the last few weeks (ATEL #2288, #2296, #2299, #2302, #2303). We observed the system on 2009 November 19 between 14:30-19:00 UT at 5 GHz with the European VLBI Network (EVN) using the e-VLBI technique. The participating radio telescopes were Effelsberg (1 Gbps), Medicina (896 Mbps), Onsala 25m (1 Gbps), Torun (1 Gbps), Westerbork (1 Gbps), Yebes (896 Mbps), and Cambridge (128 Mbps).

  6. Lessons of L'Aquila for Operational Earthquake Forecasting

    NASA Astrophysics Data System (ADS)

    Jordan, T. H.

    2012-12-01

    The L'Aquila earthquake of 6 Apr 2009 (magnitude 6.3) killed 309 people and left tens of thousands homeless. The mainshock was preceded by a vigorous seismic sequence that prompted informal earthquake predictions and evacuations. In an attempt to calm the population, the Italian Department of Civil Protection (DPC) convened its Commission on the Forecasting and Prevention of Major Risk (MRC) in L'Aquila on 31 March 2009 and issued statements about the hazard that were widely received as an "anti-alarm"; i.e., a deterministic prediction that there would not be a major earthquake. On October 23, 2012, a court in L'Aquila convicted the vice-director of DPC and six scientists and engineers who attended the MRC meeting on charges of criminal manslaughter, and it sentenced each to six years in prison. A few weeks after the L'Aquila disaster, the Italian government convened an International Commission on Earthquake Forecasting for Civil Protection (ICEF) with the mandate to assess the status of short-term forecasting methods and to recommend how they should be used in civil protection. The ICEF, which I chaired, issued its findings and recommendations on 2 Oct 2009 and published its final report, "Operational Earthquake Forecasting: Status of Knowledge and Guidelines for Implementation," in Aug 2011 (www.annalsofgeophysics.eu/index.php/annals/article/view/5350). As defined by the Commission, operational earthquake forecasting (OEF) involves two key activities: the continual updating of authoritative information about the future occurrence of potentially damaging earthquakes, and the officially sanctioned dissemination of this information to enhance earthquake preparedness in threatened communities. Among the main lessons of L'Aquila is the need to separate the role of science advisors, whose job is to provide objective information about natural hazards, from that of civil decision-makers who must weigh the benefits of protective actions against the costs of false alarms

  7. The narrative epidemiology of L'Aquila 2009 earthquake.

    PubMed

    Casacchia, M; Pollice, R; Roncone, R

    2012-03-01

    The authors describe their experience working and living in L'Aquila, where at 3.32 a.m., early in the morning of 6 April 2009, a 6.3 Richter magnitude earthquake caused serious damages to this 13th century town (with a population of 72 000 and a health district of 103 788), in the mountainous Abruzzo region and to several medieval hill villages in the surrounding areas: 309 residents were killed, over 1600 were injured, 66 000 residents were displaced, and, the centre of L'Aquila, the main historical and artistic centre of Abruzzo, was totally destroyed. Here is described the work done at the Psychiatric Unit of the General Hospital of L'Aquila and in the University. The Authors report the incidence rate of Acute Stress Disorder (ASD) in help-seekers (full ASD 4.9%, and partial ASD 39.3%), and of post-traumatic stress disorder (PTSD) found in different samples of population (range 12-37.5). The authors express their consideration about which real-world variables can reflect the population distress and the naturalistic process of recovery in such natural disasters. After the earthquake they hypothesize that a lot of residents had found their way to recover through 'writing, telling the story', by analogy with what narrative medicine asserts, thus estimating the positive effect of 'emotional disclosure' on health. A large number of materials (books, web-blogs, videos) were produced by residents and a database of memories was implemented. The suffering and struggle to recover in the aftermaths of a traumatic experience often yields remarkable transformations and positive growth. From this point of view, the authors underline the increased virtual relationships of residents through Facebook, to cope with the loss of previous social relationships, to get information about recreational opportunities, or to get organized for public events, despite their displacement. Many collective demonstrations were organized and showed the will to actively participate to the

  8. Structural damages of L'Aquila (Italy) earthquake

    NASA Astrophysics Data System (ADS)

    Kaplan, H.; Bilgin, H.; Yilmaz, S.; Binici, H.; Öztas, A.

    2010-03-01

    On 6 April 2009 an earthquake of magnitude 6.3 occurred in L'Aquila city, Italy. In the city center and surrounding villages many masonry and reinforced concrete (RC) buildings were heavily damaged or collapsed. After the earthquake, the inspection carried out in the region provided relevant results concerning the quality of the materials, method of construction and the performance of the structures. The region was initially inhabited in the 13th century and has many historic structures. The main structural materials are unreinforced masonry (URM) composed of rubble stone, brick, and hollow clay tile. Masonry units suffered the worst damage. Wood flooring systems and corrugated steel roofs are common in URM buildings. Moreover, unconfined gable walls, excessive wall thicknesses without connection with each other are among the most common deficiencies of poorly constructed masonry structures. These walls caused an increase in earthquake loads. The quality of the materials and the construction were not in accordance with the standards. On the other hand, several modern, non-ductile concrete frame buildings have collapsed. Poor concrete quality and poor reinforcement detailing caused damage in reinforced concrete structures. Furthermore, many structural deficiencies such as non-ductile detailing, strong beams-weak columns and were commonly observed. In this paper, reasons why the buildings were damaged in the 6 April 2009 earthquake in L'Aquila, Italy are given. Some suggestions are made to prevent such disasters in the future.

  9. Cepheid companions? FM Aquilae, FN Aquilae, RX Aurigae, Y Lacertae, and RS Orionis

    NASA Technical Reports Server (NTRS)

    Evans, Nancy Remage; Szabados, Laszlo; Udalska, Joanna

    1990-01-01

    IUE spectra have been used to search for companions of FN Aql and RX Aur, two classical Cepheids which have been tentatively identified as binary stars on the basis of cyclic variations in their pulsation periods. Three other Cepheids, FM Aql, Y Lac, and RS Ori, suspected of having blue companions from the (U-B), (B-V) diagram, have also been investigated. There is no indication of a companion of FM Aql, FN Aql, and RX Aur. If these stars have companions, they must be at least as cool as A0 V, Al V, and A1 V, respectively.

  10. The contribution of L'Aquila (Italy) Geomagnetic Observatory to MAGDAS project

    NASA Astrophysics Data System (ADS)

    Lepidi, S.; Meloni, A.; Palangio, P.; Yumoto, K.

    2011-12-01

    The geomagnetic Observatory of L'Aquila (Italy) was founded by Istituto Nazionale di Geofisica e Vulcanologia (INGV) in 1958, on the occasion of the International Geophysical Year. It is the main Italian geomagnetic observatory. Since 1999 L'Aquila Observatory belongs to the Intermagnet system, an International network grouping worldwide geomagnetic observatories able to provide Earth's magnetic field measurements according to precise quality standards. Geomagnetic field measurements in L'Aquila are used to study the variations of the Earth's geomagnetic field, both of internal and external origin. In November 2008 a new magnetometer was installed in L'Aquila within the MAGDAS project, coordinated by SERC. The location of this installation can be useful to complete the MAGDAS monitoring system to study solar-terrestrial events.

  11. Holleman in X-1 Reaction Control Cockpit

    NASA Technical Reports Server (NTRS)

    1958-01-01

    The X-1B and X-1E were simulated several times between 1956 and 1958 on both the AFFTC and NACA/NASA analog computers. The X-1 simulations were used for pilot training, envelope expansion studies, roll and inertial coupling studies, and reaction control studies.

  12. High-Resolution Parallax Measurements of Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Bradshaw, C. F.; Fomalont, E. B.; Geldzahler, B. J.

    1999-02-01

    The results of eight VLBA observations at 5 GHz, spanning 3 yr, have yielded a measured trigonometric parallax for Sco X-1 of 0.00036"+/-0.00004" hence, its distance is 2.8+/-0.3 kpc. This is the most precise parallax measured to date. Although our measured distance is 40% farther away than previous estimates based on X-ray luminosity, our Rossi X-Ray Timing Explorer observations, with a measured luminosity of 2.3×1038 ergs s-1, and determined distance continue to support the hypothesis that Z-source low-mass X-ray binary systems, like Sco X-1, radiate at the Eddington luminosity at a particular point in their X-ray color-color diagram.

  13. The X-Ray Spectral Changes of Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Bradshaw, C. F.; Geldzahler, B. J.; Fomalont, E. B.

    2003-07-01

    Rossi X-Ray Timing Explorer (RXTE) observations of Sco X-1 during 1997-1999 have been analyzed for spectral characteristics. All the X-ray branches of Sco X-1 were observed during these epochs. On the basis of our observations, we present a simple model for the behavior of Sco X-1 as a function of accretion rate and angle of the observer's line of sight that explains quantitatively the results of VLBA and RXTE observations. Our model presents a unified view of bright low-mass X-ray binaries as an accretion-driven system in which, at the Eddington accretion rate, material overflows the magnetosphere of the neutron star and quenches the jets of Sco X-1. We present supporting evidence of absorption as a function of X-ray branch. The model explains the two distinct color diagrams of observed Z source horizontal branches as variations in the observed line of sight to the accretion disk. The model also applies to the recently discovered Z traces in atoll sources.

  14. SMC X-1 variability observed from HEAO 1

    NASA Technical Reports Server (NTRS)

    Gruber, D. E.; Rothschild, R. E.

    1984-01-01

    Studies are reported of the slow variability of SMC X-1 and its spectrum. An analysis of red-noise random variability is based on a method discussed by Deeter and Boynton (1982). The 0.7 s X-ray pulsar SMC X-1 is in a 3.89 day eclipsing binary system with a B0 I supergiant companion. Observations of the pulsar were conducted with the aid of the UCSD/MIT instrument on HEAO 1 from 1977 August through 1979 January. A light curve was constructed for the period 1977 September to 1978 December. The apparent tendency of SMC X-1 to be in one of two states, high or low, suggests the acquisition of average spectra separately for each state. The total (steady plus pulsed) emission from SMC X-1 displays a continuum spectrum with a dominant exponential form which implies a temperature of 17 keV for thin thermal bremsstrahlung emission or 5 keV if the other limit of a Wien spectrum is assumed.

  15. Herschel Observations of Circinus X-1 during Outburst and Quiescence

    NASA Astrophysics Data System (ADS)

    Harrison, Thomas E.; Gelino, Dawn M.; Buxton, Michelle; Fost, Tyler

    2014-07-01

    We have used the Photodetector Array Camera and Spectrometer and Spectral and Photometric Imaging REceiver instruments on the Herschel Space Observatory to observe Cir X-1 both in and out of outburst. We detected Cir X-1 during outburst at 70 μm. Unfortunately, a cold background source dominates Cir X-1 at longer wavelengths. We have assembled optical and infrared (IR) data for Cir X-1 to model its spectral energy distribution (SED) in both quiescence and outburst and find that in both states it is consistent with a heavily reddened, 10,000 K blackbody. We believe this behavior is completely consistent with previous suggestions that these outbursts are due to accretion disk events, not unlike those of dwarf novae. To explore the behavior of other low-mass X-ray binaries with reported synchrotron jets, we have extracted and/or compiled optical and near- and mid-IR data sets for five such systems to construct their SEDs. The Z-source GX 349+2 and the black hole system GRS 1915+105 have strong and variable mid-IR excesses that suggest synchrotron emission. The other Z-sources have rather weak (or no) IR excesses that can be explained as reddened blackbody spectra with the addition of either synchrotron or bremsstrahlung components. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  16. Herschel observations of Circinus X-1 during outburst and quiescence

    SciTech Connect

    Harrison, Thomas E.; Gelino, Dawn M.; Buxton, Michelle; Fost, Tyler E-mail: dawn@ipac.caltech.edu E-mail: tyler.fost@gmail.com

    2014-07-01

    We have used the Photodetector Array Camera and Spectrometer and Spectral and Photometric Imaging REceiver instruments on the Herschel Space Observatory to observe Cir X-1 both in and out of outburst. We detected Cir X-1 during outburst at 70 μm. Unfortunately, a cold background source dominates Cir X-1 at longer wavelengths. We have assembled optical and infrared (IR) data for Cir X-1 to model its spectral energy distribution (SED) in both quiescence and outburst and find that in both states it is consistent with a heavily reddened, 10,000 K blackbody. We believe this behavior is completely consistent with previous suggestions that these outbursts are due to accretion disk events, not unlike those of dwarf novae. To explore the behavior of other low-mass X-ray binaries with reported synchrotron jets, we have extracted and/or compiled optical and near- and mid-IR data sets for five such systems to construct their SEDs. The Z-source GX 349+2 and the black hole system GRS 1915+105 have strong and variable mid-IR excesses that suggest synchrotron emission. The other Z-sources have rather weak (or no) IR excesses that can be explained as reddened blackbody spectra with the addition of either synchrotron or bremsstrahlung components.

  17. Radio non-detection of Aql X-1

    NASA Astrophysics Data System (ADS)

    Tudose, V.; Paragi, Z.; Altamirano, D.; Miller-Jones, J. C. A.; Garrett, M.; Fender, R.; Rushton, A.; Spencer, R.; Maitra, D.

    2010-10-01

    The neutron star X-ray binary Aql X-1 is on the decaying phase of a major outburst that peaked at optical and X-ray bands in mid-September (ATEL #2850, #2871, #2891, #2902). We observed the object at 5 GHz with the European VLBI Network (EVN) in the e-VLBI mode on 2010 October 4th between 18:20-22:09 UT. The participating stations were Cambridge, Effelsberg, Jodrell Bank (MkII), Hartebeesthoek, Medicina, Onsala, Torun, Westerbork and Yebes.

  18. Operational effectiveness of a Multiple Aquila Control System (MACS)

    NASA Technical Reports Server (NTRS)

    Brown, R. W.; Flynn, J. D.; Frey, M. R.

    1983-01-01

    The operational effectiveness of a multiple aquila control system (MACS) was examined under a variety of remotely piloted vehicle (RPV) mission configurations. The set of assumptions and inputs used to form the rules under which a computerized simulation of MACS was run is given. The characteristics that are to govern MACS operations include: the battlefield environment that generates the requests for RPV missions, operating time-lines of the RPV-peculiar equipment, maintenance requirements, and vulnerability to enemy fire. The number of RPV missions and the number of operation days are discussed. Command, control, and communication data rates are estimated by determining how many messages are passed and what information is necessary in them to support ground coordination between MACS sections.

  19. Young Stellar Object Candidates in the Aquila Rift Region

    NASA Astrophysics Data System (ADS)

    Zhang, Miao-miao; Wang, Hong-chi; Stecklum, B.

    2010-10-01

    Using the 2m telescope of the Turingia State Observatory at Tauten-berg (TLS), imaging observations in 3 wavebands (H α, R and I) are performed in the 16 fields in the Aquila Rift region. The observed fields cover about 7 square degrees. Excluding the 3 fields with unqualified data, the photometrical analysis is made for the remaining 13 fields, from which point sources are identified, and finally 7 H α emission-line star candidates are identified by color-color diagrams. The 7 candidates are located in five fields. Three of them are located near the Galactic plane, while the galactic latitudes of the rest are greater than 4°. The 2 M ASS counterparts of the point sources are identified, and the properties of the 7 H α emission-line star candidates are further analyzed by using the two-color diagrams. It is found that the near-infrared radiation from these H α emission-line star candidates has no obvious infrared excess, one of them even falls on the main-sequence branch. This indicates that the H α-emissive young stellar objects (YSOs) are not always accompanied with the infrared excess, and that the results of the H α emission line observation and the infrared excess observation are mutually supplemented. If the 7 H α emission-line star candidates are regarded as YSO candidates, then the number of YSOs in the Aquila Rift region is quite small. The further confirmation of these candidates needs subsequent spectral observations.

  20. Biological Anomalies around the 2009 L’Aquila Earthquake

    PubMed Central

    Fidani, Cristiano

    2013-01-01

    Simple Summary Earthquakes have been seldom associated with reported non-seismic phenomena observed weeks before and after shocks. Non-seismic phenomena are characterized by radio disturbances and light emissions as well as degassing of vast areas near the epicenter with chemical alterations of shallow geospheres (aquifers, soils) and the troposphere. Many animals are sensitive to even the weakest changes in the environment, typically responding with behavioral and physiological changes. A specific questionnaire was developed to collect data on these changes around the time of the 2009 L’Aquila earthquake. Abstract The April 6, 2009 L’Aquila earthquake was the strongest seismic event to occur in Italy over the last thirty years with a magnitude of M = 6.3. Around the time of the seismic swarm many instruments were operating in Central Italy, even if not dedicated to biological effects associated with the stress field variations, including seismicity. Testimonies were collected using a specific questionnaire immediately after the main shock, including data on earthquake lights, gas leaks, human diseases, and irregular animal behavior. The questionnaire was made up of a sequence of arguments, based upon past historical earthquake observations and compiled over seven months after the main shock. Data on animal behavior, before, during and after the main shocks, were analyzed in space/time distributions with respect to the epicenter area, evidencing the specific responses of different animals. Several instances of strange animal behavior were observed which could causally support the hypotheses that they were induced by the physical presence of gas, electric charges and electromagnetic waves in atmosphere. The aim of this study was to order the biological observations and thereby allow future work to determine whether these observations were influenced by geophysical parameters. PMID:26479529

  1. X-1A in flight over lakebed

    NASA Technical Reports Server (NTRS)

    1953-01-01

    The Bell Aircraft Corporation X-1A (48-1384) returning from an Air Force test flight over Edwards Air Force Base, California in late 1953. A North American F-86A Sabre as chase plane will follow the X-1A to touchdown. The Rogers Dry Lake is the whitish area under the planes with the airfield at the edge of the dry lake. Bell test pilot Jean 'Skip' Ziegler made six flights between 14 February and 25 April 1953. Air Force test pilots Maj. Charles 'Chuck' Yeager and Maj. Arthur 'Kit' Murray made 18 test flights between 21 November 1953 and 26 August 1954. NACA test pilot Joseph Walker made one successful flight on 20 July 1955. During a second flight attempt, on 8 August 1955, an explosion damaged the aircraft shortly before launch. Walker, unhurt, climbed up into the JTB-29A mothership, and the X-1A was jettisoned over the Edwards AFB bombing range. There were five versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system

  2. X-1E with Pilot Joe Walker

    NASA Technical Reports Server (NTRS)

    1958-01-01

    A photo of the X-1E with pilot Joe Walker suited up at the NASA High-Speed Flight Station, Edwards, California. The dice and 'Little Joe' are prominently displayed under the cockpit area. (Little Joe is a dice players slang term for two deuces.) Five years later when Walker reached 354,200 feet in the X-15, that aircraft carried similar artwork - 'Little Joe the II.' Walker is shown in the photo above wearing an early partial pressure suit. This protected the pilot if cockpit pressure was lost above 50,000 feet. There were five versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on Jan. 25, 1946. Powered flights began in December 1946

  3. X-1E Engine Ground Test Run

    NASA Technical Reports Server (NTRS)

    1956-01-01

    The Bell Aircraft Corporation X-1E during a ground engine test run on the NACA High-Speed Flight Station ramp near the Rogers Dry Lake. The rocket technician is keeping the concrete cool by hosing it with water during the test. This also helps in washing away any chemicals that might spill. The test crew worked close to the aircraft during ground tests. There were four versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Supersonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on January 25, 1946. Powered flights began in December 1946. On October 14, 1947, the X-1-1, piloted by Air Force Captain Charles 'Chuck' Yeager, became the first aircraft to exceed the speed of sound, reaching about

  4. Ultraviolet spectroscopy of binary systems

    NASA Technical Reports Server (NTRS)

    Dupree, A. K.; Hartmann, L.; Raymond, J. C.

    1980-01-01

    Four typical binary systems that illustrate some of the major problems in the study of binary stars are discussed. Consideration is given to (1) high-luminosity X-ray sources typified by Cyg X-1 (HDE 226868) and Vela XR-1 (HD 77581), (2) low-luminosity X-ray sources (HZ Her), (3) late-type systems of W UMa and RS CVn type, and (4) cool supergiants with a hot companion (VV Cephei).

  5. X-1E with Pilot Joe Walker

    NASA Technical Reports Server (NTRS)

    1958-01-01

    A photo of the X-1E with pilot Joe Walker suited up at the NASA High-Speed Flight Station, Edwards, California. The dice and 'Little Joe' are prominently displayed under the cockpit area. (Little Joe is a dice players slang term for two deuces.) Five years later when Walker reached 354,200 feet in the X-15, that aircraft carried similar artwork - 'Little Joe the II.' Walker is shown in the photo above wearing an early partial pressure suit. This protected the pilot if cockpit pressure was lost above 50,000 feet. There were five versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on Jan. 25, 1946. Powered flights began in December 1946

  6. X-1E canopy mock-up

    NASA Technical Reports Server (NTRS)

    1953-01-01

    This photo appears to depict the design of the X-1E canopy. In 1955, the X-1-2 was modified. The modifications included a new thin wing and a low-pressure fuel system. The most visible change was a raised canopy that replaced the original flush windshield on the aircraft, which was called the X-1E. The modified aircraft made its first glide flight on December 12, 1955, and its first powered flight three days later. Over a three-year period, the X-1E made a total of 26 flights, reaching a speed of Mach 2.24. National Advisory Committee for Aeronautics (NACA) pilot Joseph Walker was the pilot for flights 1 through 21, while John McKay made flights 22 to 26. The final flight occurred on November 6, 1958. This was also the last flight by an X-1 aircraft. On April 29, 1960, the X-1E was mounted on a pole in front of the Flight Research Center (FRC) headquarters building. In 1976 the FRC became the Hugh L. Dryden Flight Research Center, and the X-1E remained in front of the headquarters building. There were five versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many

  7. Understanding the Cray X1 System

    NASA Technical Reports Server (NTRS)

    Cheung, Samson

    2004-01-01

    This paper helps the reader understand the characteristics of the Cray X1 vector supercomputer system, and provides hints and information to enable the reader to port codes to the system. It provides a comparison between the basic performance of the X1 platform and other platforms that are available at NASA Ames Research Center. A set of codes, solving the Laplacian equation with different parallel paradigms, is used to understand some features of the X1 compiler. An example code from the NAS Parallel Benchmarks is used to demonstrate performance optimization on the X1 platform.

  8. Discovery of orbital decay in SMC X-1

    NASA Technical Reports Server (NTRS)

    Levine, A.; Rappaport, S.; Boynton, P.; Deeter, J.; Nagase, F.

    1992-01-01

    The results are reported of three observations of the binary X ray pulsar SMC X-1 with the Ginga satellite. Timing analyses of the 0.71 s X ray pulsations yield Doppler delay curves which, in turn, provide the most accurate determination of the SMC X-1 orbital parameters available to date. The orbital phase of the 3.9 day orbit is determined in May 1987, Aug. 1988, and Aug. 1988 with accuracies of 11, 1, and 3.5 s, respectively. These phases are combined with two previous determinations of the orbital phase to yield the rate of change in the orbital period: P sub orb/P sub orb = (-3.34 + or - 0.023) x 10(exp -6)/yr. An interpretation of this measurement and the known decay rate for the orbit of Cen X-3 is made in the context of tidal evolution. Finally, a discussion is presented of the relation among the stellar evolution, orbital decay, and neutron star spinup time scales for the SMC X-1 system.

  9. Swift/XRT confirms the new outburst of Aql X-1

    NASA Astrophysics Data System (ADS)

    Sanna, A.; Riggio, A.; Pintore, F.; Altamirano, D.; Burderi, L.; Di Salvo, T.

    2016-08-01

    Triggered by the X-ray enhancement observed by Swift/BAT on 2016 July 29 at a position compatible with the low mass X-ray binary Aql X-1 (Atel #9287), a 500 s observation with Swift/XRT was promptly carried out. Swift/XRT operating in Photon Counting mode detected a single bright X-ray source.

  10. X-1-2 on ramp

    NASA Technical Reports Server (NTRS)

    1951-01-01

    The Bell Aircraft Corporation X-1-2 aircraft on the ramp at NACA High Speed Flight Research Station located on the South Base of Muroc Army Air Field in 1947. The X-1-2 flew until October 23, 1951, completing 74 glide and powered flights with nine different pilots. The aircraft has white paint and the NACA tail band. The black Xs are reference markings for tracking purposes. They were widely used on NACA aircraft in the early 1950s. There were five versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on Jan. 25, 1946. Powered flights began in December 1946. On Oct. 14, 1947, the X-1-1, piloted by Air Force Captain Charles 'Chuck' Yeager

  11. Time series analysis of the cataclysmic variable V1101 Aquilae

    NASA Astrophysics Data System (ADS)

    Spahn, Alexander C.

    This work reports on the application of various time series analysis techniques to a two month portion of the light curve of the cataclysmic variable V1101 Aquilae. The system is a Z Cam type dwarf nova with an orbital period of 4.089 hours and an active outburst cycle of 15.15 days due to a high mass transfer rate. The system's light curve also displays higher frequency variations, known as negative sumperhums, with a period of 3.891 hours and a period deficit of --5.1%. The amplitude of the negative superhumps varies as an inverse function of system brightness, with an amplitude of 0.70358 during outburst and 0.97718 during quiescence (relative flux units). These variations are believed to be caused by the contrast between the accretion disk and the bright spot. An O--?C diagram was constructed and reveals the system's evolution. In general, during the rise to outburst, the disk moment of inertia decreases as mass is lost from the disk, causing the precession period of the tilted disk to increase and with it the negative superhump period. The decline of outburst is associated with the opposite effects. While no standstills were observed in this data, they are present in the AAVSO data and the results agree with the conditions for Z Cam stars.

  12. Biological Anomalies around the 2009 L'Aquila Earthquake.

    PubMed

    Fidani, Cristiano

    2013-01-01

    The April 6, 2009 L'Aquila earthquake was the strongest seismic event to occur in Italy over the last thirty years with a magnitude of M = 6.3. Around the time of the seismic swarm many instruments were operating in Central Italy, even if not dedicated to biological effects associated with the stress field variations, including seismicity. Testimonies were collected using a specific questionnaire immediately after the main shock, including data on earthquake lights, gas leaks, human diseases, and irregular animal behavior. The questionnaire was made up of a sequence of arguments, based upon past historical earthquake observations and compiled over seven months after the main shock. Data on animal behavior, before, during and after the main shocks, were analyzed in space/time distributions with respect to the epicenter area, evidencing the specific responses of different animals. Several instances of strange animal behavior were observed which could causally support the hypotheses that they were induced by the physical presence of gas, electric charges and electromagnetic waves in atmosphere. The aim of this study was to order the biological observations and thereby allow future work to determine whether these observations were influenced by geophysical parameters. PMID:26479529

  13. AGU Statement: Investigation of Scientists and Officials in L'Aquila, Italy, Is Unfounded

    NASA Astrophysics Data System (ADS)

    2010-07-01

    Seven Italian scientists and government officials are under investigation on charges of manslaughter for failure to warn the city of L'Aquila, Italy, before an earthquake hit last year, killing hundreds. The six seismologists and one government official under investigation, who are employees of the National Institute for Geophysics and Volcanology (INGV) and the Civil Protection Department, took part in a meeting of the Major Risks Committee on 31 March 2009. At the meeting, the committee told L'Aquila city officials that “just because a small series of quakes has been observed [in L'Aquila] there is no reason to suggest that the sequence of low-magnitude tremors are a precursor to a major event,” which was deemed “improbable, although not impossible.” However, on 6 April 2009, the city was struck by a Mw 6.3 earthquake that killed 308 people.

  14. Aperiodic and Quasi-Periodic Variability in Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Parker, Neil Ivan

    Low mass X-ray binary star systems (LMXBs) are among the brightest and most well-studied objects in the X-ray sky-indeed, the first extrasolar X-ray source discovered, Sco X-1, is an LMXB. But despite the wealth of available data, LMXBs remain enigmatic, in large part due to the fact that they show little or no coherent periodicity. LMXBs show aperiodic and quasi-periodic variability, for which the underlying mechanisms are poorly understood. Much information remains locked in archival data. Here we address this issue by re-analyzing archival EXOSAT data of Sco X-1 using modern time-series techniques, including multi-tapering, wavelet transforms and scalegrams, and nonlinear dynamical modelling, which are not yet commonly used in the analysis of astronomical data, with the goal of characterizing Sco X-1's variability and developing a formalism to take us from timing data to mathematical models to astrophysical models. The power spectra of Sco X-1 show several components: (i) very low frequency noise (VLFN), a colored noise component seen below ~0.25 Hz, (ii) high frequency noise (HFN), a colored noise component seen above ~30-40 Hz, and (iii) quasi-periodic oscillations (QPOs), localized excesses of Fourier power. The VLFN contains ~1.3% [1/over2]-peak-to-peak pulsed power on the average, can be described by a power law with an index of ~1.4, and is correlated with the 'flickeriness' of the source. QPOs contain ~4.6% [1/over2]-peak-to-peak pulsed power, have centroid frequencies of 6.7 Hz or 15 Hz, and are associated with extended 'quiescent' states and with brief gaps in 'flaring' states. HFN is difficult to characterize (though others have had success describing it as a damped power law), and is not strongly associated with any other source feature. It contains ~2.1% [1/over2]-peak-to-peak pulsed power. Several models have been proposed to explain the VLFN, QPOs, and HFN in Sco X-1, but none are completely satisfactory. Most models seek to explain only QPOs. Here

  15. Community mental health service utilization after the L'Aquila earthquake.

    PubMed

    Stratta, Paolo; de Cataldo, Stefano; Bonanni, Roberto L; Rossi, Alessandro

    2015-05-01

    This study investigated the use of the facilities for the mental health by the population affected by the L'Aquila (Italy) 2009 earthquake. The data about the activities of the Mental Health Centre of L'Aquila during the years from 2008 to 2010 were obtained by the service Information System. In the months following the event the percentage of referrals was reduced. Failure to use specialized facilities after disasters should not be seen as reassuring. It is conceivable that a relevant rate of frank or sub-threshold psychopathology is present that the traditional mental health facilities may not be able to intercept. PMID:25540028

  16. AR1429 Releases X1 Class Flare

    NASA Video Gallery

    The Solar Dynamics Observatory captured the X1 flare, shown here in the 171 Angstrom wavelength, a wavelength typically shown in the color gold. This movie runs from 10 PM ET March 4 to 3 AM March ...

  17. Highly Structured Wind in Vela X-1

    NASA Technical Reports Server (NTRS)

    Kreykenbohm, Ingo; Wilms, Joern; Kretschmar, Peter; Torrejon, Jose Miguel; Pottschmidt, Katja; Hanke, Manfred; Santangelo, Andrea; Ferrigno, Carlo; Staubert, Ruediger

    2008-01-01

    We present an in-depth analysis of the spectral and temporal behavior of a long almost uninterrupted INTEGRAL observation of Vela X-1 in Nov/Dec 2003. In addition to an already high activity level, Vela X-1 exhibited several very intense flares with a maximum intensity of more than 5 Crab in the 20 40 keV band. Furthermore Vela X-1 exhibited several off states where the source became undetectable with ISGRI. We interpret flares and off states as being due to the strongly structured wind of the optical companion: when Vela X-1 encounters a cavity in the wind with strongly reduced density, the flux will drop, thus potentially triggering the onset of the propeller effect which inhibits further accretion, thus giving rise to the off states. The required drop in density to trigger the propeller effect in Vela X-1 is of the same order as predicted by theoretical papers for the densities in the OB star winds. The same structured wind can give rise to the giant flares when Vela X-1 encounters a dense blob in the wind. Further temporal analysis revealed that a short lived QPO with a period of 6800 sec is present. The part of the light curve during which the QPO is present is very close to the off states and just following a high intensity state, thus showing that all these phenomena are related.

  18. Energy dependence of normal branch oscillations in Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Wang, J.; Chang, H.-K.; Liu, C.-Y.

    2012-11-01

    We report the energy dependence of normal branch oscillations (NBOs) in Scorpius X-1, a low-mass X-ray binary Z-source. Three characteristic quantities (centroid frequency, quality factor, and fractional root-mean-squared (rms) amplitude) of a quasi-periodic oscillation signal as functions of photon energy are investigated. We found that, although it is not yet statistically well established, there is a signature indicating that the NBO centroid frequency decreases with increasing photon energy when it is below 6-8 keV, which turns out to be positively correlated with the photon energy at the higher energy side. In addition, the rms amplitude increases significantly with the photon energy below 13 keV and then decreases in the energy band of 13-20 keV. There is no clear dependence on photon energy for the quality factor. Based on these results, we suggest that the NBO originates mainly in the transition layer.

  19. Discovery of orbital decay in SMC X-1

    NASA Technical Reports Server (NTRS)

    Levine, A.; Rappaport, S.; Deeter, J. E.; Boynton, P. E.; Nagase, F.

    1993-01-01

    Three observations of the binary X-ray pulsar SMC X-1 with the Ginga satellite, conducted on 3 days in 1987 May, 8.4 days in 1988 August-September, and 4 days in 1989 July-August, are reported. Based on the three observation epochs, the rate of change in the orbital period is estimated at (-3.36 +/- 0.02) x 10 exp -6/yr. An interpretation of the orbital decay is made in the context of tidal evolution with allowance for the effect of the increasing moment of inertia of the companion star due to its nuclear evolution. While the orbital decay is thought to be driven by tidal interactions, it is suggested that the asynchronism between the orbit and the rotation of the companion star is most likely maintained by the evolutionary expansion of the companion star (Sk 160) rather than via the Darwin instability.

  20. NACA Aircraft on Lakebed - D-558-2, X-1B, and X-1E

    NASA Technical Reports Server (NTRS)

    1955-01-01

    Early NACA research aircraft on the lakebed at the High Speed Research Station in 1955: Left to right: X-1E, D-558-2, X-1B There were four versions of the original Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Supersonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on January 25, 1946. Powered flights began in December 1946. On October 14, 1947, the X-1-1, piloted by Air Force Captain Charles 'Chuck' Yeager, became the first aircraft to exceed the speed of sound, reaching about 700 miles per hour (Mach 1.06) and an altitude of 43,000 feet. The number 2 X-1 was modified and redesignated the X-1E. The modifications included adding a conventional canopy, an ejection seat, a low-pressure fuel system

  1. The Mass Donor of Scorpius X-1 Revealed

    NASA Astrophysics Data System (ADS)

    Steeghs, D.; Casares, J.

    2002-03-01

    We present the first detection of the mass donor star in the prototype X-ray binary Scorpius X-1. Phase-resolved spectroscopy revealed narrow emission line components from the irradiated secondary star. Radial velocity fits to the Bowen blend emission are used to establish an absolute orbital ephemeris and derive an accurate value for the systemic velocity, γ=-113.8+/-0.6 km s-1. Emission from the irradiated front side of the secondary leads to solid limits to the radial velocity of the mass donor of 87<~K2<~148 km s-1. In conjunction with an upper limit to the velocity of the primary K1<=53 km s-1, we derive a firm limit on the mass ratio of Sco X-1 of q<~0.61. A likely set of system parameters satisfying the various constraints as well as the recent inclination estimate by Fomalont, Geldzahler, & Bradshaw (2001) is K1=40 km s-1, K2=133 km s-1, q=0.30 corresponding to component masses of M1=1.4Msolar and M2=0.42Msolar for an orbital inclination of 38°.

  2. Shell-shocked: the interstellar medium near Cygnus X-1

    NASA Astrophysics Data System (ADS)

    Sell, P. H.; Heinz, S.; Richards, E.; Maccarone, T. J.; Russell, D. M.; Gallo, E.; Fender, R.; Markoff, S.; Nowak, M.

    2015-02-01

    We conduct a detailed case study of the interstellar shell near the high-mass X-ray binary, Cygnus X-1. We present new WIYN optical spectroscopic and Chandra X-ray observations of this region, which we compare with detailed MAPPINGS III shock models, to investigate the outflow powering the shell. Our analysis places improved, physically motivated constraints on the nature of the shock wave and the interstellar medium (ISM) it is plowing through. We find that the shock is travelling at less than a few hundred km s-1 through a low-density ISM (<5 cm-3). We calculate a robust, 3σ upper limit to the total, time-averaged power needed to drive the shock wave and inflate the bubble, <2 × 1038 erg s-1. We then review possible origins of the shock wave. We find that a supernova origin to the shock wave is unlikely and that the black hole jet and/or O-star wind can both be central drivers of the shock wave. We conclude that the source of the Cygnus X-1 shock wave is far from solved.

  3. The nature of the companion star in Circinus X-1

    NASA Astrophysics Data System (ADS)

    Johnston, Helen M.; Soria, Roberto; Gibson, Joel

    2016-02-01

    We present optical spectra and images of the X-ray binary Circinus X-1. The optical light curve of Cir X-1 is strongly variable, changing in brightness by 1.2 mag in the space of four days. The shape of the light curve is consistent with that seen in the 1980s, when the X-ray and radio counterparts of the source were at least ten times as bright as they are currently. We detect strong, variable H α emission lines, consisting of multiple components which vary with orbital phase. We estimate the extinction to the source from the strength of the diffuse interstellar bands and the Balmer decrement; the two methods give AV = 7.6 ± 0.6 mag and AV > 9.1 mag, respectively. The optical light curve can be modelled as arising from irradiation of the companion star by the central X-ray source, where a low-temperature star fills its Roche lobe in an orbit of moderate eccentricity (e ˜ 0.4). We suggest that the companion star is overluminous and underdense, due to the impact of the supernova which occurred less than 5000 yr ago.

  4. FUSE observations of a full orbit of Scorpius X-1

    SciTech Connect

    Boroson, Bram; Vrtilek, Saeqa Dil; Raymond, John E-mail: svrtilek@cfa.harvard.edu

    2014-09-20

    We obtained UV spectra of X-ray binary Scorpius X-1 in the 900-1200 Å range with the Far Ultraviolet Spectroscopic Explorer over the full 0.79 day binary orbit. The strongest emission lines are the doublet of O VI at 1032,1038 Å and the C III complex at 1175 Å. The spectrum is affected by a multitude of narrow interstellar absorption lines, both atomic and molecular. Examination of line variability and Doppler tomograms suggests emission from both the neighborhood of the donor star and the accretion disk. Models of turbulence and Doppler broadened Keplerian disk lines Doppler shifted with the orbit of the neutron star added to narrow Gaussian emission lines with undetermined Doppler shift fit the data with consistent values of disk radius, inclination, and radial line brightness profile. The Doppler shift of the narrow component with the orbit suggests an association with the donor star. We test our line models with previously analyzed near UV spectra obtained with the Hubble Space Telescope (HST) Goddard High Resolution Spectrograph and archival spectra obtained with the HST Cosmic Origins Spectrograph.

  5. Myths and realities about the recovery of L׳Aquila after the earthquake

    PubMed Central

    Contreras, Diana; Blaschke, Thomas; Kienberger, Stefan; Zeil, Peter

    2014-01-01

    There is a set of myths which are linked to the recovery of L׳Aquila, such as: the L׳Aquila recovery has come to a halt, it is still in an early recovery phase, and there is economic stagnation. The objective of this paper is threefold: (a) to identify and develop a set of spatial indicators for the case of L׳Aquila, (b) to test the feasibility of a numerical assessment of these spatial indicators as a method to monitor the progress of a recovery process after an earthquake and (c) to answer the question whether the recovery process in L׳Aquila stagnates or not. We hypothesize that after an earthquake the spatial distribution of expert defined variables can constitute an index to assess the recovery process more objectively. In these articles, we aggregated several indicators of building conditions to characterize the physical dimension, and we developed building use indicators to serve as proxies for the socio-economic dimension while aiming for transferability of this approach. The methodology of this research entailed six steps: (1) fieldwork, (2) selection of a sampling area, (3) selection of the variables and indicators for the physical and socio-economic dimensions, (4) analyses of the recovery progress using spatial indicators by comparing the changes in the restricted core area as well as building use over time; (5) selection and integration of the results through expert weighting; and (6) determining hotspots of recovery in L׳Aquila. Eight categories of building conditions and twelve categories of building use were identified. Both indicators: building condition and building use are aggregated into a recovery index. The reconstruction process in the city center of L׳Aquila seems to stagnate, which is reflected by the five following variables: percentage of buildings with on-going reconstruction, partial reconstruction, reconstruction projected residential building use and transport facilities. These five factors were still at low levels within the

  6. Cray X1 Evaluation Status Report

    SciTech Connect

    Vetter, J.S.

    2004-02-09

    On August 15, 2002 the Department of Energy (DOE) selected the Center for Computational Sciences (CCS) at Oak Ridge National Laboratory (ORNL) to deploy a new scalable vector supercomputer architecture for solving important scientific problems in climate, fusion, biology, nanoscale materials and astrophysics. ''This program is one of the first steps in an initiative designed to provide U.S. scientists with the computational power that is essential to 21st century scientific leadership,'' said Dr. Raymond L. Orbach, director of the department's Office of Science The Cray X1 is an attempt to incorporate the best aspects of previous Cray vector systems and massively-parallel-processing (MPP) systems into one design. Like the Cray T90, the X1 has high memory bandwidth, which is key to realizing a high percentage of theoretical peak performance. Like the Cray T3E, the X1 has a high-bandwidth, low-latency, scalable interconnect, and scalable system software. And, like the Cray SV1, the X1 leverages commodity off-the-shelf (CMOS) technology and incorporates non-traditional vector concepts, like vector caches and multi-streaming processors. In FY03, CCS procured a 256-processor Cray X1 to evaluate the processors, memory subsystem, scalability of the architecture, software environment and to predict the expected sustained performance on key DOE applications codes. The results of the micro-benchmarks and kernel benchmarks show the architecture of the Cray X1 to be exceptionally fast for most operations. The best results are shown on large problems, where it is not possible to fit the entire problem into the cache of the processors. These large problems are exactly the types of problems that are important for the DOE and ultra-scale simulation.

  7. Binary Plutinos

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.

    2015-08-01

    The Pluto-Charon binary was the first trans-neptunian binary to be identified in 1978. Pluto-Charon is a true binary with both components orbiting a barycenter located between them. The Pluto system is also the first, and to date only, known binary with a satellite system consisting of four small satellites in near-resonant orbits around the common center of mass. Seven other Plutinos, objects in 3:2 mean motion resonance with Neptune, have orbital companions including 2004 KB19 reported here for the first time. Compared to the Cold Classical population, the Plutinos differ in the frequency of binaries, the relative sizes of the components, and their inclination distribution. These differences point to distinct dynamical histories and binary formation processes encountered by Plutinos.

  8. Wavelet analysis of fast photometry on Cygnus X-1 with the AstraLux camera

    SciTech Connect

    Luque-Escamilla, P. L.; Marti, J.; Combi, Jorge A.; Arjonilla, Alvaro Munoz; Sanchez-Sutil, J. R.

    2008-10-08

    We present sub-second fast photometry for the high mass X-ray binary Cygnus X-1. We try to observe variability due to instabilities in the accretion process at optical wavelengths. The observations were carried out using the high speed AstraLux camera at the Calar Alto 2.2 m telescope, Spain, in November 2006 and August 2007. We report that the Cygnus X-1 system light curve sampled every 30 milli-second did not display strong enough evidence of any periodic component related to the source.

  9. New challenges for seismology and decision makers after L'Aquila trial

    NASA Astrophysics Data System (ADS)

    Marzocchi, Warner

    2013-04-01

    On 22 October seven experts who attended a Major Risk Committee meeting were sentenced to six years in prison on charges of manslaughter for underestimating the risk before the devastating 6.3-magnitude earthquake that struck the hillside city of L'Aquila on 6 April 2009, which caused more than 300 deaths. The earthquake followed a sequence of seismic events that started at the beginning of the year, with the largest shock - a 4.2-magnitude earthquake - occurring on 30 March. A day later, the seven experts met in L'Aquila; the minutes of the meeting, which were released after the quake, contained three main conclusions: that earthquakes are not predictable in a deterministic sense; that the L'Aquila region has the highest seismic hazard in Italy; and that the occurrence of a large earthquake in the short term was unlikely. There is not doubt that this trial will represent an important turning point for seismologists, and more in general for scientists who serve as advisors for public safety purposes. Here, starting from the analysis of the accusations made by the prosecutor and a detailed scientific appraisal of what happened, we try to figure out how seismology can evolve in order to be more effective in protecting people, and (possibly) avoiding accusations like the ones who characterize the L'Aquila trial. In particular, we discuss (i) the principles of the Operational Earthquake Forecasting that were put forward by an international Commission on Earthquake Forecasting (ICEF) nominated after L'Aquila earthquake, (ii) the ICEF recommendations for Civil Protection, and (iii) the recent developments in this field in Italy. Finally, we also explore the interface between scientists and decision makers, in particular in the framework of making decisions in a low probability environment.

  10. SUPERORBITAL PHASE-RESOLVED ANALYSIS OF SMC X-1

    SciTech Connect

    Hu, Chin-Ping; Chou, Yi; Yang, Ting-Chang; Su, Yi-Hao E-mail: yichou@astro.ncu.edu.tw

    2013-08-10

    The high-mass X-ray binary SMC X-1 is an eclipsing binary with an orbital period of 3.89 days. This system exhibits a superorbital modulation with a period varying between {approx}40 days and {approx}65 days. The instantaneous frequency and the corresponding phase of the superorbital modulation can be obtained by a recently developed time-frequency analysis technique, the Hilbert-Huang transform (HHT). We present a phase-resolved analysis of both the spectra and the orbital profiles with the superorbital phase derived from the HHT. The X-ray spectra observed by the Proportional Counter Array on board the Rossi X-ray Timing Explorer are fitted well by a blackbody plus a Comptonized component. The plasma optical depth, which is a good indicator of the distribution of material along the line of sight, is significantly anti-correlated with the flux detected at 2.5-25 keV. However, the relationship between the plasma optical depth and the equivalent width of the iron line is not monotonic. There is no significant correlation for fluxes higher than {approx}35 mCrab but clear positive correlation when the intensity is lower than {approx}20 mCrab. This indicates that the iron line production is dominated by different regions of this binary system in different superorbital phases. To study the dependence of the orbital profile on the superorbital phase, we obtained the eclipse profiles by folding the All Sky Monitor light curve with the orbital period for different superorbital states. A dip feature, similar to the pre-eclipse dip in Her X-1, lying at orbital phase {approx}0.6-0.85, was discovered during the superorbital transition state. This indicates that the accretion disk has a bulge that absorbs considerable X-ray emission in the stream-disk interaction region. The dip width is anti-correlated with the flux, and this relation can be interpreted by the precessing tilted accretion disk scenario.

  11. Complex earthquake directivity during the 2009 L'Aquila mainshock

    NASA Astrophysics Data System (ADS)

    Tinti, E.; Scognamiglio, L.; Cirella, A.; Cocco, M.; Piatanesi, A.

    2012-04-01

    The normal faulting rupture characteristics of the 2009 L'Aquila earthquake have been deeply studied by several authors by using different data set (broad-band and strong-motion seismic data, and surface deformation measurements, such as GPS and InSAR). Most of the published source models have highlighted the complexity of the rupture process and have shown a clear south-eastward rupture directivity. Besides, the key feature of the source process retrieved by Cirella et al. (2012) reveals two distinct stages of rupture history. The rupture initially propagates up-dip from the hypocenter at relatively high rupture velocity and with a modest moment release. Successively, nearly two seconds after nucleation, the rupture proceeds towards SE, along the strike direction, breaking the largest and deeper asperity. The up-dip and along-strike rupture propagation are separated in time and associated with a Mode II and a Mode III crack, respectively. There are clues suggesting a second, less evident, near-source up-dip directivity occurring before the well known south-eastward directivity. For this reason we investigate in detail the first seconds of the rupture to unravel the up-dip propagation. The near-fault strong motion data show a remarkably short duration of strong shaking. In particular, the comparative energy (calculated with a cumulative sum of square acceleration) computed for the three components of the closest stations at frequencies below 0.4 Hz are not well reproduced by using the available kinematic models, suggesting that the complexity of the rupture process has been not completely understood. We first study the effect of the source-to-receiver geometry on comparative energy, through several forward modeling of point sources located on the fault, up-dip from the hypocenter. Therefore, we perform a non-linear inversion of strong motion and CGPS data with an epicentral distance less than 30 km; then we use the retrieved model to compute the dynamic rupture

  12. NACA Aircraft on Lakebed - D-558-2, X-1B, and X-1E

    NASA Technical Reports Server (NTRS)

    1955-01-01

    Early NACA research aircraft on the lakebed at the High Speed Research Station in 1955: Left to right: X-1E, D-558-2, X-1B There were four versions of the original Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Supersonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on January 25, 1946. Powered flights began in December 1946. On October 14, 1947, the X-1-1, piloted by Air Force Captain Charles 'Chuck' Yeager, became the first aircraft to exceed the speed of sound, reaching about 700 miles per hour (Mach 1.06) and an altitude of 43,000 feet. The number 2 X-1 was modified and redesignated the X-1E. The modifications included adding a conventional canopy, an ejection seat, a low-pressure fuel system

  13. K2 and MAXI observations of Sco X-1 - evidence for disc precession?

    NASA Astrophysics Data System (ADS)

    Hakala, Pasi; Ramsay, Gavin; Barclay, Thomas; Charles, Phil

    2015-10-01

    Sco X-1 is the archetypal low-mass X-ray binary and the brightest persistent extrasolar X-ray source in the sky. It was included in the K2 Campaign 2 field and was observed continuously for 71 d with 1 min time resolution. In this Letter, we report these results and underline the potential of K2 for similar observations of other accreting compact binaries. We reconfirm that Sco X-1 shows a bimodal distribution of optical `high' and `low' states and rapid transitions between them on time-scales less than 3 h (or 0.15 orbits). We also find evidence that this behaviour has a typical systemic time-scale of 4.8 d, which we interpret as a possible disc precession period in the system. Finally, we confirm the complex optical versus X-ray correlation/anticorrelation behaviour for `high' and `low' optical states, respectively.

  14. Late Quaternary river incision rate from L'Aquila-Scoppito Basin (central Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Nocentini, Marco; Tallini, Marco; Asti, Riccardo; Cosentino, Domenico

    2014-05-01

    L'Aquila-Scoppito Basin (ASB) is part of the wider L'Aquila Basin, one of the most tectonically active intermontane basins of central Apennines (Italy). ASB is a semi-enclosed intermontane sedimentary basin of morphotectonic origin, W-E trending and approximately 20 km2 wide, with mean elevations ranging between 850 and 650 m a.s.l. and it is crossed by two main water courses: the Aterno River and the Raio Creek. Structurally, the ASB may be considered as an half-graben, bordered northerly by the south-dipping Scoppito-Preturo normal Fault and easterly by the southwest dipping Pettino Fault. In the L'Aquila-Scoppito Basin a series of erosional and depositional post Middle Pleistocene events generated three order of fluvial terraces, generally not completely preserved. The first order of fluvial terrace, the Vetoio Synthem (T1), is a fill terrace carved into both the L'Aquila Breccia Synthem (Middle Pleistocene) and the Madonna della Strada Synthem (Lower Pleistocene), whose top is preserved near the L'Aquila airport and the S. Salvatore hospital, approximately at 20-25 m above the present thalweg of the Aterno River. The second order of terrace, the Pile Synthem (T2), is a strath terrace embedded into T1 and carved into both the Lower Pleistocene deposits and the pre-Quaternary bedrock. The top of T2 is located at 10-13 m above the present thalweg of the Raio Creek. Charcoaled plant remains founded within the sandy layers of T2 give a 14C 2σ age of 41854-40464 BP (MIS 3). This age is in agreement with traces of lithic industry of Mousterian age (late Middle Paleolithic) inside the gravels. The youngest order of terrace, Ponte Peschio Synthem (T3), lies 5-7 m above both the Raio and the Aterno thalwegs. T3 is embedded into T1 and carved in the L'Aquila Breccia Synthem, near the S. Salvatore hospital, while at Ponte Peschio it is embedded into T2 and is carved directly into the pre-Quaternary bedrock. Then, also T3 may be interpreted as a strath terrace. River

  15. Faulkes Telescope observations of the optical rise of a bright outburst of Aql X-1

    NASA Astrophysics Data System (ADS)

    Russell, David M.; Lewis, Fraser

    2016-08-01

    The neutron star X-ray binary transient, Aql X-1 has just entered a new outburst. Swift/BAT detected an increase in the hard X-ray flux starting on 2016 July 29 (MJD 57598; ATel #9287), followed by a confirmation from Swift/XRT that the source is detected and bright at 0.3-10 keV (ATel #9292) and by July 31 the optical flux had also brightened (ATel #9293).

  16. Implications of cyclotron features in the X-ray spectrum of Her X-1

    NASA Technical Reports Server (NTRS)

    Bussard, R.

    1979-01-01

    The X-ray spectra from binary pulsars is investigated through the modification of physical processes due to an intense magnetic field. An effective scattering cross section for line photons and the Coulomb cross section for electron-ion collisions, treating the electrons relativistically, are calculated. The quantization of electron orbits in strong fields are discussed. The absorption cross sections and emission rates for cyclotron photons are calculated. An application of the results to the data from Hercules X-1 is examined.

  17. Origin of multi-band emission from the microquasar Cygnus X-1

    SciTech Connect

    Zhang, Jianfu; Lu, Jufu; Xu, Bing

    2014-06-20

    We study the origin of non-thermal emissions from the Galactic black hole X-ray binary Cygnus X-1, which is a confirmed high-mass microquasar. By analogy with the methods used in studies of active galactic nuclei, we propose a two-dimensional, time-dependent radiation model from the microquasar Cygnus X-1. In this model, the evolution equation for relativistic electrons in a conical jet are numerically solved by including escape, adiabatic, and various radiative losses. The radiative processes involved are synchrotron emission, its self-Compton scattering, and inverse Compton scatterings of an accretion disk and its surrounding stellar companion. This model also includes an electromagnetic cascade process of an anisotropic γ-γ interaction. We study the spectral properties of electron evolution and its emission spectral characteristic at different heights of the emission region located in the jet. We find that radio data from Cygnus X-1 are reproduced by the synchrotron emission, the Fermi Large Area Telescope measurements by the synchrotron emission and Comptonization of photons of the stellar companion, and the TeV band emission fluxes by the Comptonization of the stellar photons. Our results show the following. (1) The radio emission region extends from the binary system scales to the termination of the jet. (2) The GeV band emissions should originate from the distance close to the binary system scales. (3) The TeV band emissions could be inside the binary system, and these emissions could be probed by the upcoming Cherenkov Telescope Array. (4) The MeV tail emissions, which produce a strongly linearly polarized signal, are emitted inside the binary system. The location of the emissions is very close to the inner region of the jet.

  18. Space X1 First Entry Sample

    NASA Technical Reports Server (NTRS)

    James, John T.

    2012-01-01

    One mini-grab sample container (m-GSC) was returned aboard Space X1 because of the importance of quickly knowing first-entry conditions in this new commercial module. This sample was analyzed alongside samples of the portable clean room (PCR) used in the Space X complex at KSC. The recoveries of C-13-acetone, fluorobenzene, and chlorobenzene from the GSCs averaged 130, 129, and 132 %, respectively.

  19. New results from long-term observations of Cyg X-1

    NASA Technical Reports Server (NTRS)

    Holt, S. S.; Boldt, E. A.; Serlemitsos, P. J.; Kaluzienski, L. J.

    1975-01-01

    Observations of Cyg X-1 between October 1974 and July 1975 reveal a persistent 5.6 day modulation of the 3 to 6 keV X-ray intensity, having a minimum in phase with superior conjunction of the HDE 226868 binary system. The modulation is found to be most pronounced just prior to the April-May 1975 increase of Cyg X-1, after which both the modulation and intensity are at their lowest values for the entire duration of the observations. These data imply that the X-ray emission from Cyg X-1 arises from the compact member of HDE 226868, and that the increase of April-May 1975 may have represented the depletion of accreting material which was not mixed into a cylindrically symmetric accretion disk about the compact member.

  20. New results from long-term observations of Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Holt, S. S.; Boldt, E. A.; Serlemitsos, P. J.; Kaluzienski, L. J.

    1976-01-01

    Observations of Cyg X-1 between October 1974 and July 1975 reveal a persistent 5.6-day modulation of the 3-6 keV X-ray intensity, having a minimum in phase with superior conjunction of the HDE 226868 binary system. The modulation is found to be most pronounced just prior to the April-May 1975 increase of Cyg X-1, after which both the modulation and intensity are at their lowest values for the entire duration of the observations. These data imply that the X-ray emission from Cyg X-1 arises from the compact member of HDE 226868, and that the increase of April-May 1975 may have represented the depletion of accreting material which had not yet been mixed into a cylindrically symmetric accretion disk about the compact member.

  1. New results from long-term observations of Cyg X-1

    NASA Technical Reports Server (NTRS)

    Holt, S. S.; Boldt, E. A.; Serlemitsos, P. J.; Kaluzienski, L. J.

    1976-01-01

    Observations of Cyg X-1 between October 1974 and July 1975 reveal a persistent 5.6 day modulation of the 3-6 keV X-ray intensity, having a minimum in phase with superior conjunction of the HDE 226868 binary system. The modulation is found to be most pronounced just prior to the April-May 1975 increase of Cyg X-1, after which both the modulation and intensity are at their lowest values for the entire duration of the observations. These data imply that the X-ray emission from Cyg X-1 arises from the compact member of HDE 226868, and that the increase of April-May 1975 may have represented the depletion of accreting material which had not yet been mixed into a cylindrically symmetric accretion disk about the compact member.

  2. The radio 'lobes' of Scorpius X-1 are unrelated background sources

    NASA Technical Reports Server (NTRS)

    Fomalont, E. B.; Geldzahler, B. J.

    1991-01-01

    The VLA between 1981 and 1990 are used to produce high-resolution images of the radio emission from the region near Sco X-1. The radio proper motion of Sco X-1 was measured at 0.0148 +/-0.0011/yr, which agrees with the optical determination for the X-ray-emitting binary system. The proper motions of two nearby radio sources, juxtaposed 1 arcmin to the NE and to the SW, were measured and found to be stationary in the sky with upper limits of 0.004 arcsec/yr. A deep radio image of the 10-arcsec extended SW source shows a morphology strikingly similar to that of a typical luminous extragalactic radio source, which contains two edge-brightened lobes, a jet, and a core. The possibilities that the NE source, although nearly stationary in the sky, is associated with Sco X-1, are discussed, and it is concluded that it is an unrelated background source. It is inferred that Sco X-1 is not a miniature triple source or a 'microquasar', and its radio emission is confined to the binary system.

  3. 10 microsecond time resolution studies of Cygnus X-1

    SciTech Connect

    Wen, H.C.

    1997-06-01

    Time variability analyses have been applied to data composed of event times of X-rays emitted from the binary system Cygnus X-1 to search for unique black hole signatures. The X-ray data analyzed was collected at ten microsecond time resolution or better from two instruments, the High Energy Astrophysical Observatory (HEAO) A-1 detector and the Rossi X-ray Timing Explorer (XTE) Proportional Counter Array (PCA). HEAO A-1 and RXTE/PCA collected data from 1977--79 and from 1996 on with energy sensitivity from 1--25 keV and 2--60 keV, respectively. Variability characteristics predicted by various models of an accretion disk around a black hole have been searched for in the data. Drop-offs or quasi-periodic oscillations (QPOs) in the Fourier power spectra are expected from some of these models. The Fourier spectral technique was applied to the HEAO A-1 and RXTE/PCA data with careful consideration given for correcting the Poisson noise floor for instrumental effects. Evidence for a drop-off may be interpreted from the faster fall off in variability at frequencies greater than the observed breaks. Both breaks occur within the range of Keplerian frequencies associated with the inner edge radii of advection-dominated accretion disks predicted for Cyg X-1. The break between 10--20 Hz is also near the sharp rollover predicted by Nowak and Wagoner`s model of accretion disk turbulence. No QPOs were observed in the data for quality factors Q > 9 with a 95% confidence level upper limit for the fractional rms amplitude at 1.2% for a 16 M{sub {circle_dot}} black hole.

  4. Experimental evidence of electrification processes during the 2009 L'Aquila earthquake main shock

    NASA Astrophysics Data System (ADS)

    Nenovski, P.

    2015-09-01

    Two types of coseismic magnetic field events are simultaneously observed: transient offset events and magnetic field signal that occurred at the destructive, Mw6.1 L'Aquila earthquake main shock. The offset event, conventionally interpreted as a signature of piezomagnetic effects, however, could not be explained as such. In the second type of coseismic event, the transient magnetic signal starts simultaneously with the offset event and reaches amplitude of 0.8 nT in the total magnetic field. The signal is a local one; its amplitude shape resembles diffusion-like form with time scale characteristics that are indicative for a source deep in the crust. The polarity of the transient signal is in the horizontal plane and nearly parallel to the L'Aquila fault strike.

  5. Detection of a bright radio flare of Cygnus X-1 at 7.2 GHz with the Sardinia Radio Telescope

    NASA Astrophysics Data System (ADS)

    Egron, E.; Pellizzoni, A.; Bachetti, M.; Navarrini, A.; Trois, A.; Pilia, M.; Iacolina, M. N.; Melis, A.; Concu, R.; Loru, S.; Sessini, A.; Grinberg, V.; Nowak, M.; Markoff, S.; Pottschmidt, K.; Rodriguez, J.; Wilms, J.; Ballhausen, R.; Corbel, S.; Eikmann, W.; Fuerst, F.; Kreykenbohm, I.; Marongiu, M.; Possenti, A.

    2016-05-01

    In the framework of radio monitoring of NS/BH Galactic Binaries with Sardinia Radio Telescope (www.srt.inaf.it) during SRT Early Science Program S0013 (PI Egron), we detected Cyg X-1 in C-band through on-the-fly mapping centered on the source position (see also Atels #8921, #8849, #8821).

  6. Up-dip directivity in near-source during the 2009 L'Aquila main shock

    NASA Astrophysics Data System (ADS)

    Tinti, Elisa; Scognamiglio, Laura; Cirella, Antonella; Cocco, Massimo

    2014-09-01

    In this study we have investigated the directivity associated with the initial up-dip rupture propagation during the 2009 April 6 (Mw 6.1) L'Aquila normal-faulting earthquake. The objective is the understanding of how the peculiar initial behaviour of rupture history during the main shock has affected the near-source recorded ground motions in the L'Aquila town and surrounding areas. We have modelled the observed ground velocities at the closest near-source recording sites by computing synthetic seismograms using a discrete wavenumbers and finite difference approach in the low frequency bandwidth (0.02-0.4 Hz) to avoid site effects contaminations. We use both the rupture model retrieved by inverting ground motion waveforms and continuous high sampling-rate GPS time-series as well as uniform-slip constant-rupture speed models. Our results demonstrate that the initial up-dip rupture propagation, characterizing the first 3 s of the rupture history during the L'Aquila main shock and releasing only ˜25 per cent of total seismic moment, controls the observed ground motions in the near-source. This initial stage of the rupture is characterized by the generation of ground velocity pulses, which we interpret as a forward directivity effect. Our modelling results confirm a heterogeneous distribution of rupture velocity during the initial up-dip rupture propagation, since uniform rupture speed models overestimate up-dip directivity effects in the footwall of the causative fault. The up-dip directivity observed in the near field during the 2009 L'Aquila main shock is that expected for a normal faulting earthquake, but it differs from that inferred from far-field observations that conversely provide evidence of along-strike directivity. This calls for a careful analysis as well as for the realistic inclusion of rupture directivity to predict ground motions in the near source.

  7. Discovery of Orbital Decay in SMC X-1

    NASA Technical Reports Server (NTRS)

    Levine, A.; Rappaport, S.; Deeter, J. E.; Boynton, P. E.; Nagase, F.

    1993-01-01

    We report on the results of three observations of the binary X-ray pulsar SMC X-1 with the Ginga satellite. Timing analyses of the 0.71 s X-ray pulsations yield Doppler delay curves which, in turn, enable the most accurate determination of the SMC X-1 orbital parameters available to date. Epochs of phase zero for the 3.9 day orbit were determined for 1987 May, 1988 August, and 1989 August with accuracies of 13, 0.6, and 3 s, respectively. These epochs are combined with two previous determinations of the orbital epoch to yield the rate of change in the orbital period dot-P(orb)/P(orb) = ( 3.36 +/- 0.02) x 10(exp -6) yr(exp -1). An interpretation of the orbital decay is made in the context of tidal evolution, with consideration of the influence of the increasing moment of inertia of the companion star due to its nuclear evolution. We find that, while the orbital decay is probably driven by tidal interactions, the asynchronism between the orbit and the rotation of the companion star is most likely maintained by the evolutionary expansion of the companion star (Sk 160) rather than via the Darwin instability. In this case Sk 160 is likely to be in the hydrogen shell burning phase of its evolution. Finally, a discussion is presented of the relation among the time scales for stellar evolution (less than 10(exp 7) yr), orbital decay (3 x 10(exp 5) yr), and neutron-star spin-up in the SMC X-1 system (2000 yr). In particular, we present the result of a self-consistent calculation for the histories of the spin of the neutron star and the mass transfer in this system. A plausible case can be made for the spin-up time scale being directly related to the lifetime of the luminous X-ray phase which will end in a common-envelope phase within a time of less than approx. 10(exp 4) yr.

  8. Long-term studies with the Ariel-5 asm. 1: Her X-1, Vela X-1 and Cen X-3. [periodic variations

    NASA Technical Reports Server (NTRS)

    Holt, S. S.; Kaluzienski, L. J.; Boldt, E. A.; Serlemitsos, P. J.

    1978-01-01

    Twelve hundred days of 3-6 keV X-ray data from Her X-1, Vela X-1 and Cen X-3 accumulated with the Ariel-5 all-sky monitor are interrogated. The binary periodicities of all three can be clearly observed, as can the approximately 35-d variation of Her X-1, for which we can refine the period to 34.875 plus or minus .030-d. No such longer-term periodicity less than 200-d is observed from Vela X-1. The 26.6-d low-state recurrence period for Cen X-3 previously suggested is not observed, but a 43.0-d candidate periodicity is found which may be consistent with the precession of an accretion disk in that system. The present results are illustrative of the long-term studies which can be performed on approximately 50 sources over a temporal base which will ultimately extend to at least 1800 days.

  9. ORNL Cray X1 evaluation status report

    SciTech Connect

    Agarwal, P.K.; Alexander, R.A.; Apra, E.; Balay, S.; Bland, A.S; Colgan, J.; D'Azevedo, E.F.; Dongarra, J.J.; Dunigan Jr., T.H.; Fahey, M.R.; Fahey, R.A.; Geist, A.; Gordon, M.; Harrison, R.J.; Kaushik, D.; Krishnakumar, M.; Luszczek, P.; Mezzacappa, A.; Nichols, J.A.; Nieplocha, J.; Oliker, L.; Packwood, T.; Pindzola, M.S.; Schulthess, T.C.; Vetter, J.S.; White III, J.B.; Windus, T.L.; Worley, P.H.; Zacharia, T.

    2004-05-01

    On August 15, 2002 the Department of Energy (DOE) selected the Center for Computational Sciences (CCS) at Oak Ridge National Laboratory (ORNL) to deploy a new scalable vector supercomputer architecture for solving important scientific problems in climate, fusion, biology, nanoscale materials and astrophysics. ''This program is one of the first steps in an initiative designed to provide U.S. scientists with the computational power that is essential to 21st century scientific leadership,'' said Dr. Raymond L. Orbach, director of the department's Office of Science. In FY03, CCS procured a 256-processor Cray X1 to evaluate the processors, memory subsystem, scalability of the architecture, software environment and to predict the expected sustained performance on key DOE applications codes. The results of the micro-benchmarks and kernel bench marks show the architecture of the Cray X1 to be exceptionally fast for most operations. The best results are shown on large problems, where it is not possible to fit the entire problem into the cache of the processors. These large problems are exactly the types of problems that are important for the DOE and ultra-scale simulation. Application performance is found to be markedly improved by this architecture: - Large-scale simulations of high-temperature superconductors run 25 times faster than on an IBM Power4 cluster using the same number of processors. - Best performance of the parallel ocean program (POP v1.4.3) is 50 percent higher than on Japan s Earth Simulator and 5 times higher than on an IBM Power4 cluster. - A fusion application, global GYRO transport, was found to be 16 times faster on the X1 than on an IBM Power3. The increased performance allowed simulations to fully resolve questions raised by a prior study. - The transport kernel in the AGILE-BOLTZTRAN astrophysics code runs 15 times faster than on an IBM Power4 cluster using the same number of processors. - Molecular dynamics simulations related to the phenomenon of

  10. X1X1X2X2/X1X2Y sex chromosome systems in the Neotropical Gymnotiformes electric fish of the genus Brachyhypopomus.

    PubMed

    Cardoso, Adauto Lima; Pieczarka, Julio Cesar; Nagamachi, Cleusa Yoshiko

    2015-05-01

    Several types of sex chromosome systems have been recorded among Gymnotiformes, including male and female heterogamety, simple and multiple sex chromosomes, and different mechanisms of origin and evolution. The X1X1X2X2/X1X2Y systems identified in three species of this order are considered homoplasic for the group. In the genus Brachyhypopomus, only B. gauderio presented this type of system. Herein we describe the karyotypes of Brachyhypopomus pinnicaudatus and B. n. sp. FLAV, which have an X1X1X2X2/X1X2Y sex chromosome system that evolved via fusion between an autosome and the Y chromosome. The morphology of the chromosomes and the meiotic pairing suggest that the sex chromosomes of B. gauderio and B. pinnicaudatus have a common origin, whereas in B . n. sp. FLAV the sex chromosome system evolved independently. However, we cannot discard the possibility of common origin followed by distinct processes of differentiation. The identification of two new karyotypes with an X1X1X2X2/X1X2Y sex chromosome system in Gymnotiformes makes it the most common among the karyotyped species of the group. Comparisons of these karyotypes and the evolutionary history of the taxa indicate independent origins for their sex chromosomes systems. The recurrent emergence of the X1X1X2X2/X1X2Y system may represent sex chromosomes turnover events in Gymnotiformes. PMID:26273225

  11. The Lukewarm Absorber in the Microquasar Cir X-1

    NASA Astrophysics Data System (ADS)

    Schulz, Norbert S.; Galloway, D. K.; Brandt, W. N.

    2006-09-01

    Through many observations in the last decades the extreme and violent X-ray binary Cir X-1 has been classified as a microquasar, Z-source, X-ray burster, and accreting neutron star exhibiting ultrarelativistic jets. Since the launch of Chandra the source underwent a dramatic change from a high flux (1.5 Crab) source to a rather low persistent flux ( 30 mCrab) in the last year. Spectra from Chandra High Energy Transmission Grating Spectrometer (HETGS) taken during this transformation have revealed many details besides the large overall flux change ranging from blue-shifted absorption lines indicating high-velocity (< 2000 km/s) outflows during high flux, persistently bright lines emission throughout all phases to some form of warm absorption in the low flux phase. Newly released atomic data allows us to analyse specifically the Fe K line region with unprecedented detail for all flux phases observed so far. We also compare these new results with recently released findings of warm absorbers and outflow signatures observed in other microqasars such as GX 339+4, GRS J1655-40, and GRS1915+115.

  12. Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Harris, Alan W.; Pravec, P.

    2006-06-01

    There are now nearly 100 binary asteroids known. In the last year alone, 30 binary asteroids have been discovered, half of them by lightcurves showing eclipse events. Similar to eclipsing binary stars, such observations allow determination of orbit period and sizes and shapes of the primary and secondary relative to the orbital dimension. From these parameters one can estimate the mean density of the system, and a number of dynamical properties such as total specific angular momentum, tidal evolution time scales of spins and orbit, and precession frequencies of the orbit about the primary and of the solar induced "general precession" of the system. We have extracted parameters for all systems with enough observations to allow meaningful determinations. Some preliminary results include: (1) Binaries are roughly as prevalent among small main-belt asteroids as among Near-Earth Asteroids. (2) Most binaries are partially asynchronous, with the secondary synchronized to the orbit period, but the primary still spinning much faster. This is consistent with estimated tidal damping time scales. (3) Most systems have near the critical maximum angular momentum for a single "rubble pile" body, but not much more, and some less. Thus fission appears not to be a viable formation mechanism for all binaries, although near-critical spin rate seems to play a role. (4) Orbits of the secondaries are essentially in the equatorial plane of the primary. Since most primary spins are still fast, the satellites must have been formed into low inclination orbits. (5) Precession frequencies are in the range of the shorter resonance frequencies in the solar system (tens of thousands of years), thus resonance interactions can be expected to have altered spin orientations as systems evolved slowly by tidal friction or other processes. (6) Primaries are unusually spheroidal, which is probably necessary for stability of the binary once formed.

  13. Correlations between X-ray Spectra and kHz QPOS in Sco X-1

    NASA Astrophysics Data System (ADS)

    Bradshaw, Charles F.; Titarchuk, Lev; Kuznetsov, Sergey

    2008-05-01

    Recent analysis of the RXTE X-ray spectra of Sco X-1 discovered that Sco X-1 can be adequately modeled by a simple two-component model of Compton up-scattering with a soft photon electron temperature of about 0.4 keV, plus an Iron K-line. The results show a strong correlation between spectral power law index and kHz QPOs. Sco X-1 is the prototypical Z-source low-mass X-ray binary (LMXB) system radiating near the Eddington limit. This radiation produces a high radiation pressure in its Compton cloud. We infer that the radiation pressure produces a geometrical configuration of the cloud that is quasi-spherical. We conclude that the high Thomson optical depth of the Compton cloud, in the range of 5-6 from the best-fit model parameters, is consistent with the neutron star's surface being obscured by material, which would likely suppress a spin frequency of Sco X-1 due to photon scattering off cloud electrons. We also demonstrate the evolution of its power spectrum when Sco X-1 transitions from the horizontal branch to the normal branch.

  14. THE ORBITAL PERIOD OF SCORPIUS X-1

    SciTech Connect

    Hynes, Robert I.; Britt, Christopher T.

    2012-08-10

    The orbital period of Sco X-1 was first identified by Gottlieb et al. While this has been confirmed on multiple occasions, this work, based on nearly a century of photographic data, has remained the reference in defining the system ephemeris ever since. It was, however, called into question when Vanderlinde et al. claimed to find the one-year alias of the historical period in RXTE/All-Sky Monitor data and suggested that this was the true period rather than that of Gottlieb et al. We examine data from the All Sky Automated Survey (ASAS) spanning 2001-2009. We confirm that the period of Gottlieb et al. is in fact the correct one, at least in the optical, with the one-year alias strongly rejected by these data. We also provide a modern time of minimum light based on the ASAS data.

  15. Leon X-1, the First Chandra Source

    NASA Technical Reports Server (NTRS)

    Weisskopf, Martin C.; Aldcroft, Tom; Cameron, Robert A.; Gandhi, Poshak; Foellmi, Cedric; Elsner, Ronald F.; Patel, Sandeep K.; ODell, Stephen L.

    2004-01-01

    Here we present an analysis of the first photons detected with the Chandra X-ray Observatory and an identification of the brightest source in the field which we named Leon X-1 to honor the momentous contributions of the Chandra Telescope Scientist, Leon Van Speybroeck. The observation took place immediately following the opening of the last door protecting the X-ray telescope. We discuss the unusual operational conditions as the first extra-terrestrial X-ray photons reflected from the telescope onto the ACIS camera. One bright source was a p parent to the team at the control center and the small collection of photons that appeared on the monitor were sufficient to indicate that the telescope had survived the launch and was approximately in focus, even prior to any checks and subsequent adjustments.

  16. X-ray time lags and non-linear variability in the ultraluminous X-ray sources NGC 5408 X-1 and NGC 6946 X-1

    NASA Astrophysics Data System (ADS)

    Hernández-García, L.; Vaughan, S.; Roberts, T. P.; Middleton, M.

    2015-11-01

    We present our analysis of the X-ray variability of two ultraluminous X-ray sources (ULXs) based on multiple XMM-Newton observations. We show that the linear rms-flux relation is present in eight observations of NGC 5408 X-1 and also in three observations of NGC 6946 X-1, but data from other ULXs are generally not sufficient to constrain any rms-flux relation. The presence of this relation was previously reported in only two observations of NGC 5408 X-1; our results show that this is a persistent property of the variability of NGC 5408 X-1 and extends to at least one other variable ULX. We speculate this is a ubiquitous property of ULX variability, as it is for X-ray variability in other luminous accreting sources. We also recover the time delay between hard and soft bands in NGC 5408 X-1, with the soft band (<1 keV) delayed with respect to the hard band (>1 keV) by up to ˜10 s (˜0.2 rad) at frequencies above ˜few mHz. For the first time, we extend the lag analysis to lower frequencies and find some evidence for a reversal of the lag, a hard lag of ˜1 ks at frequencies of ˜0.1 mHz. Our energy-resolved analysis shows that the time delays are energy dependent. We argue that the lag is unlikely to be a result of reflection from an accretion disc (`reverberation') based on the lack of reflection features in the spectra, and the large size of the reflector inferred from the magnitude of the lag. We also argue that associating the soft lag with a quasi-periodic oscillation (QPO) in these ULXs - and drawing an analogy between soft lags in ULXs and soft lags seen in some low-frequency QPOs of Galactic X-ray binaries - is premature.

  17. Long-term change in the cyclotron line energy in Her X-1

    NASA Astrophysics Data System (ADS)

    Staubert, Rüdiger

    2016-04-01

    We investigate the long-term evolution in the centroid energy of the Cyclotron Resonance Scattering Feature (CRSF) in the spectrum of the binary X-ray pulsar Her X-1. After the discovery in 1976 by the MPE/AIT balloon telescope HEXE, the line feature was confirmed by several other instruments, establishing the centroid energy at around 35 keV, thereby providing the first direct measure of the B-filed strength of a neutron star at a few 10^12 Gauss. Between 1991 and 1993 an upward jump by ~7 keV occurred, first noted by BATSE and soon confirmed by RXTE and Beppo/SAX. Since then a systematic effort to monitor the cyclotron line energy E_cyc with all available instruments has led to two further discoveries: 1) E_cyc correlates positively with the X-ray luminosity (this feature is now found in four more binary X-ray pulsars). 2) Over the last 20 years the (flux normalized) E_cyc in Her X-1 has decayed by ~5 keV, down to 36.5 keV in August 2015. Her X-1 is the first and so far the only source showing such a variation. We will discuss possible physical scenarios relevant for accretion mounds/columns on highly magnetized neutron stars.

  18. On the orbital phase dependence of the turn-on times of Hercules X-1

    NASA Technical Reports Server (NTRS)

    Levine, A. M.; Jernigan, J. G.

    1982-01-01

    The present investigation is concerned with the dynamics of tilted accretion disks in binary systems. It is shown that the expected motion of a ring of matter in an accretion disk is more complicated than simple precession at a uniform rate. The motion is found to be better described by a vector normal to the plane of the ring of matter whose tip periodically traces out a small ellipse centered on the tip of a uniformly precessing vector. It is also demonstrated that this 'wobble' can be utilized to explain why the turn-ons of Hercules X-1 preferentially occur around orbital phases 0.2 and 0.7. If an accretion disk in a binary system is tilted with respect to the binary orbital plane, then it must undergo forced precession with the corresponding 'wobble'. This 'wobble' may be, at least, partially responsible for the phase dependence of the distribution of X-ray turn-on times of Hercules X-1.

  19. Understanding compact object formation and natal kicks. IV. The case of IC 10 X-1

    SciTech Connect

    Wong, Tsing-Wai; Valsecchi, Francesca; Ansari, Asna; Kalogera, Vassiliki; Fragos, Tassos; McClintock, Jeffrey; Glebbeek, Evert E-mail: francesca@u.northwestern.edu E-mail: tfragos@cfa.harvard.edu E-mail: ansari@ldeo.columbia.edu

    2014-08-01

    The extragalactic X-ray binary IC 10 X-1 has attracted attention as it is possibly the host of the most massive stellar-mass black-hole (BH) known to date. Here we consider all available observational constraints and construct its evolutionary history up to the instant just before the formation of the BH. Our analysis accounts for the simplest possible history, which includes three evolutionary phases: binary orbital dynamics at core collapse, common envelope (CE) evolution, and evolution of the BH-helium star binary progenitor of the observed system. We derive the complete set of constraints on the progenitor system at various evolutionary stages. Specifically, right before the core collapse event, we find the mass of the BH immediate progenitor to be ≳ 31 M{sub ☉} (at 95% of confidence, same hereafter). The magnitude of the natal kick imparted to the BH is constrained to be ≲ 130 km s{sup –1}. Furthermore, we find that the 'enthalpy' formalism recently suggested by Ivanova and Chaichenets is able to explain the existence of IC 10 X-1 without the need to invoke unreasonably high CE efficiencies. With this physically motivated formalism, we find that the CE efficiency required to explain the system is in the range of ≅ 0.6-1.

  20. New binary systems: beaming binaries

    NASA Astrophysics Data System (ADS)

    Morales, J. C.; Weingrill, J.; Mazeh, T.; Ribas, I.

    2011-11-01

    Exoplanet missions such as COROT and Kepler are providing precise photometric follow-up data of new kinds of variable stars undetected till now. Beaming binaries are among these objects. On these binary systems, the orbital motion of their components is fast enough to produce a detectable modulation on the received flux due to relativistic effects (Zucker et al. 2007). The great advantage of these systems is that it is possible to reconstruct the radial velocity curve of the system from this photometric modulation and thus, orbital parameters such as the mass ratio and the semi-major axis can be estimated from photometry without the necessity of spectroscopic follow-up. In this poster, we briefly introduce the analysis of this kind of binary systems and in particular, the eclipsing cases.

  1. Binary Planets

    NASA Astrophysics Data System (ADS)

    Ryan, Keegan; Nakajima, Miki; Stevenson, David J.

    2014-11-01

    Can a bound pair of similar mass terrestrial planets exist? We are interested here in bodies with a mass ratio of ~ 3:1 or less (so Pluto/Charon or Earth/Moon do not qualify) and we do not regard the absence of any such discoveries in the Kepler data set to be significant since the tidal decay and merger of a close binary is prohibitively fast well inside of 1AU. SPH simulations of equal mass “Earths” were carried out to seek an answer to this question, assuming encounters that were only slightly more energetic than parabolic (zero energy). We were interested in whether the collision or near collision of two similar mass bodies would lead to a binary in which the two bodies remain largely intact, effectively a tidal capture hypothesis though with the tidal distortion being very large. Necessarily, the angular momentum of such an encounter will lead to bodies separated by only a few planetary radii if capture occurs. Consistent with previous work, mostly by Canup, we find that most impacts are disruptive, leading to a dominant mass body surrounded by a disk from which a secondary forms whose mass is small compared to the primary, hence not a binary planet by our adopted definition. However, larger impact parameter “kissing” collisions were found to produce binaries because the dissipation upon first encounter was sufficient to provide a bound orbit that was then rung down by tides to an end state where the planets are only a few planetary radii apart. The long computational times for these simulation make it difficult to fully map the phase space of encounters for which this outcome is likely but the indications are that the probability is not vanishingly small and since planetary encounters are a plausible part of planet formation, we expect binary planets to exist and be a non-negligible fraction of the larger orbital radius exoplanets awaiting discovery.

  2. EPISODIC TRANSIENT GAMMA-RAY EMISSION FROM THE MICROQUASAR CYGNUS X-1

    SciTech Connect

    Sabatini, S.; Tavani, M.; Vittorini, V.; Piano, G.; Del Monte, E.; Feroci, M.; Argan, A.; D'Ammando, F.; Costa, E.; De Paris, G.; Bulgarelli, A.; Trifoglio, M.; Gianotti, F.; Di Cocco, G.; Barbiellini, G.; Caraveo, P.; Chen, A. W.

    2010-03-20

    Cygnus X-1 (Cyg X-1) is the archetypal black hole binary system in our Galaxy. We report the main results of an extensive search for transient gamma-ray emission from Cygnus X-1 carried out in the energy range 100 MeV-3 GeV by the AGILE satellite, during the period 2007 July-2009 October. The total exposure time is about 300 days, during which the source was in the 'hard' X-ray spectral state. We divided the observing intervals in 2-4 week periods, and searched for transient and persistent emission. We report an episode of significant transient gamma-ray emission detected on 2009 October 16 in a position compatible with Cyg X-1 optical position. This episode, which occurred during a hard spectral state of Cyg X-1, shows that a 1-2 day time variable emission above 100 MeV can be produced during hard spectral states, having important theoretical implications for current Comptonization models for Cyg X-1 and other microquasars. Except for this one short timescale episode, no significant gamma-ray emission was detected by AGILE. By integrating all available data, we obtain a 2{sigma} upper limit for the total integrated flux of F {sub {gamma}}{sub ,U.L.} = 3 x 10{sup -8} ph cm{sup -2} s{sup -1} in the energy range 100 MeV-3 GeV. We then clearly establish the existence of a spectral cutoff in the energy range 1-100 MeV that applies to the typical hard state outside the flaring period and that confirms the historically known spectral cutoff above 1 MeV.

  3. Gravitational waves from Scorpius X-1: A comparison of search methods and prospects for detection with advanced detectors

    NASA Astrophysics Data System (ADS)

    Messenger, C.; Bulten, H. J.; Crowder, S. G.; Dergachev, V.; Galloway, D. K.; Goetz, E.; Jonker, R. J. G.; Lasky, P. D.; Meadors, G. D.; Melatos, A.; Premachandra, S.; Riles, K.; Sammut, L.; Thrane, E. H.; Whelan, J. T.; Zhang, Y.

    2015-07-01

    The low-mass X-ray binary Scorpius X-1 (Sco X-1) is potentially the most luminous source of continuous gravitational-wave radiation for interferometers such as LIGO and Virgo. For low-mass X-ray binaries this radiation would be sustained by active accretion of matter from its binary companion. With the Advanced Detector Era fast approaching, work is underway to develop an array of robust tools for maximizing the science and detection potential of Sco X-1. We describe the plans and progress of a project designed to compare the numerous independent search algorithms currently available. We employ a mock-data challenge in which the search pipelines are tested for their relative proficiencies in parameter estimation, computational efficiency, robustness, and most importantly, search sensitivity. The mock-data challenge data contains an ensemble of 50 Scorpius X-1 (Sco X-1) type signals, simulated within a frequency band of 50-1500 Hz. Simulated detector noise was generated assuming the expected best strain sensitivity of Advanced LIGO [1] and Advanced VIRGO [2] (4 ×10-24 Hz-1 /2 ). A distribution of signal amplitudes was then chosen so as to allow a useful comparison of search methodologies. A factor of 2 in strain separates the quietest detected signal, at 6.8 ×10-26 strain, from the torque-balance limit at a spin frequency of 300 Hz, although this limit could range from 1.2 ×10-25 (25 Hz) to 2.2 ×10-26 (750 Hz) depending on the unknown frequency of Sco X-1. With future improvements to the search algorithms and using advanced detector data, our expectations for probing below the theoretical torque-balance strain limit are optimistic.

  4. [Mortality data in L'Aquila (Central Italy): few evidence, a lot of concerns].

    PubMed

    Masedu, Francesco; Valenti, Marco

    2016-01-01

    The use of mortality data in L'Aquila public health post-earthquake experience considered as a population's health status indicator is completely missed. The deficit of regional and local epidemiological network in the period preceding the earthquake has clearly revealed a lack of specific activity, for example public reporting of morbidity and mortality in the seismic crater. This absence of a systematic use of current statistics needs a serious reflection concerning investments that regional public health needs to carry out on this topic. PMID:27291213

  5. Special Session: Lessons Learned From the L'Aquila Earthquake Case

    NASA Astrophysics Data System (ADS)

    Ambrogio, Olivia

    2013-01-01

    The verdict and prison sentences, delivered on 22 October 2012, that found six Italian scientists and one government official guilty of manslaughter in connection with the 2009 L'Aquila earthquake shocked the scientific community worldwide. A late-breaking special session co-convened by John Bates, at the National Climatic Data Center of the National Oceanic and Atmospheric Administration, and Stephen Sparks, University of Bristol, was added to the Fall Meeting schedule to address this case and to discuss the complex process of assessing and communicating the risks associated with natural hazards.

  6. Macroseismic survey of the April 6, 2009 L’Aquila earthquake (central Italy)

    NASA Astrophysics Data System (ADS)

    Camassi, R.; Azzaro, R.; Bernardini, F.; D'Amico, S.; Ercolani, E.; Rossi, A.; Tertulliani, A.; Vecchi, M.; Galli, P.

    2009-12-01

    On April 6, 2009, at 01:33 GMT, central Italy has been hit by a strong earthquake (Ml 5.8, Mw 6.3) representing the mainshock of a seismic sequence of over 20.000 aftershocks recorded in about five months. The event, located in the inner of the Abruzzi region just a few kilometres SW of the town of L’Aquila, has produced destructions and heavy damage in a 30 km wide area and was felt in almost Italy, as far as the coasts of Slovenia, Croatia and Albania. In all, 308 people lost their lives. A macroseismic survey was carried out soon after the earthquake by the QUEST group (QUick Earthquake Survey Team) with the aim to define, for Civil Protection purposes, the damage scenario over a territory which is densely urbanised. Damage generally depended on the high vulnerability of the buildings both for problems related to the old age of the buildings - it is the case of the historical centre of l’Aquila - and to site effects, as in some quarters of the town and in the nearby villages. Rubble-stone and masonry buildings suffered heaviest damage - a lot of old small villages almost entirely collapsed - while reinforced concrete (RC) frame buildings generally experienced moderate structural damage except in particular condition. The macroseismic effects reached intensity IX-X MCS (Mercalli-Cancani-Sieberg scale) at Onna and Castelnuovo, while many others villages reached VIII-IX MCS, amongst which the historical centre of L’Aquila. This town was investigated in detail due to the striking difference of damage between the historical centre and the more recent surrounding areas. In all, more than 300 localities have been investigated (Galli and Camassi, 2009). The earthquake has also provoked effects on natural surroundings (EMERGEO WG, 2009). Two types of phenomena have been detected: (i) surface cracks mainly observed along previously mapped faults and (ii) slope instability processes, such as landslides and secondary fractures. The pattern of macroseismic effects

  7. e-EVN radio detection of Aql X-1 in outburst

    NASA Astrophysics Data System (ADS)

    Tudose, V.; Paragi, Z.; Yang, J.; Miller-Jones, J. C. A.; Fender, R.; Garrett, M.; Rushton, A.; Spencer, R.

    2013-06-01

    The neutron star X-ray binary Aql X-1 is currently in outburst (ATel #5114, #5117, #5129, #5136, #5148). Using the European VLBI Network (e-EVN) we observed Aql X-1 at 5 GHz in two time-slots: 2013 June 18 between 19:48 - 20:36 UT (MJD 56461.825 - 56461.858), and 2013 June 19 between 02:53 - 05:54 UT (MJD 56462.120 - 56462.246). The two datasets were combined together and then calibrated. The participating radio telescopes were: Effelsberg (Germany), Jodrell Bank Mk2 (UK), Medicina (Italy), Noto (Italy), Onsala 25m (Sweden), Torun (Poland), Yebes (Spain), Westerbork Synthesis Radio Telescope (Netherlands), Shanghai (China), Hartebeesthoek (South Africa).

  8. Studying the Warm Layer and the Hardening Factor in Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Yao, Yangsen; Zhang, Shuangnan; Zhang, Xiaoling; Feng, Yuxin

    2002-01-01

    As the first dynamically determined black hole X-ray binary system, Cygnus X-1 has been studied extensively. However, its broadband spectrum observed with BeppoSax is still not well understood. Besides the soft excess described by the multi-color disk model (MCD), the power-law hard component and a broad excess feature above 10 keV (a disk reflection component), there is also an additional soft component around 1 keV, whose origin is not known currently. Here we propose that the additional soft component is due to the thermal Comptonization between the soft disk photons and a warm plasma cloud just above the disk, i.e., a warm layer. We use the Monte-Carlo technique to simulate this Compton scattering process and build a table model based on our simulation results. With this table model, we study the disk structure and estimate the hardening factor to the MCD component in Cygnus X-1.

  9. THE HARD X-RAY BEHAVIOR OF AQL X-1 DURING TYPE-I BURSTS

    SciTech Connect

    Chen, Yu-Peng; Zhang, Shu; Zhang, Shuang-Nan; Ji, Long; Li, Jian; Wang, Jian-Min; Torres, Diego F.; Kretschmar, Peter E-mail: szhang@ihep.ac.cn

    2013-11-01

    We report the discovery of an anti-correlation between the soft and hard X-ray light curves of the X-ray binary Aql X-1 when bursting. This behavior may indicate that the corona is cooled by the soft X-ray shower fed by the type-I X-ray bursts, and that this process happens within a few seconds. Stacking the Aql X-1 light curves of type-I bursts, we find a shortage in the 40-50 keV band, delayed by 4.5 ± 1.4 s with respect to the soft X-rays. The photospheric radius expansion bursts are different in that neither a shortage nor an excess shows up in the hard X-ray light curve.

  10. The Photoionized Accretion Disk in Her X-1

    NASA Astrophysics Data System (ADS)

    Ji, L.; Schulz, N.; Nowak, M.; Marshall, H. L.; Kallman, T.

    2009-08-01

    We present an analysis of several high-resolution Chandra grating observations of the X-ray binary pulsar Her X-1. With a total exposure of 170 ks, the observations are separated by years and cover three combinations of orbital and superorbital phases. Our goal is to determine distinct properties of the photoionized emission and its dependence on phase-dependent variations of the continuum. We find that the continua can be described by a partial covering model which above 2 keV is consistent with recent results from Rossi X-Ray Timing Explorer studies and at low energies is consistent with recent XMM-Newton and BeppoSAX studies. Besides a power law with fixed index, an additional thermal blackbody of 114 eV is required to fit wavelengths above 12 Å (~1 keV). We find that likely all the variability is caused by highly variable absorption columns in the range (1-3) × 1023 cm-2. Strong Fe K line fluorescence in almost all observations reveals that dense, cool material is present not only in the outer regions of the disk but interspersed throughout the disk. Most spectra show strong line emission stemming from a photoionized accretion disk corona (ADC). We model the line emission with generic thermal plasma models as well as with the photoionization code XSTAR and investigate changes of the ionization balance with orbital and superorbital phases. Most accretion disk coronal properties such as disk radii, temperatures, and plasma densities are consistent with previous findings for the low state. We find that these properties change negligibly with respect to orbital and superorbital phases. A couple of the higher energy lines exhibit emissivities that are significantly in excess of expectations from a static ADC.

  11. THE RETURN OF THE BURSTS: THERMONUCLEAR FLASHES FROM CIRCINUS X-1

    SciTech Connect

    Linares, M.; Homan, J.; Chakrabarty, D.; Watts, A.; Altamirano, D.; Degenaar, N.; Yang, Y.; Wijnands, R.; Armas-Padilla, M.; Cavecchi, Y.; Kalamkar, M.; Kaur, R.; Patruno, A.; Van der Klis, M.; Soleri, P.; Casella, P.; Rea, N.

    2010-08-10

    We report the detection of 15 X-ray bursts with RXTE and Swift observations of the peculiar X-ray binary Circinus X-1 (Cir X-1) during its 2010 May X-ray re-brightening. These are the first X-ray bursts observed from the source after the initial discovery by Tennant and collaborators, 25 years ago. By studying their spectral evolution, we firmly identify nine of the bursts as type I (thermonuclear) X-ray bursts. We obtain an arcsecond location of the bursts that confirms once and for all the identification of Cir X-1 as a type I X-ray burst source, and therefore as a low magnetic field accreting neutron star. The first five bursts observed by RXTE are weak and show approximately symmetric light curves, without detectable signs of cooling along the burst decay. We discuss their possible nature. Finally, we explore a scenario to explain why Cir X-1 shows thermonuclear bursts now but not in the past, when it was extensively observed and accreting at a similar rate.

  12. On the Spin of the Black Hole in IC 10 X-1

    NASA Astrophysics Data System (ADS)

    Steiner, James F.; Walton, Dominic J.; García, Javier A.; McClintock, Jeffrey E.; Laycock, Silas G. T.; Middleton, Matthew J.; Barnard, Robin; Madsen, Kristin K.

    2016-02-01

    The compact X-ray source in the eclipsing X-ray binary IC 10 X-1 has reigned for years as ostensibly the most massive stellar-mass black hole, with a mass estimated to be about twice that of its closest rival. However, striking results presented recently by Laycock et al. reveal that the mass estimate, based on emission-line velocities, is unreliable and that the mass of the X-ray source is essentially unconstrained. Using Chandra and NuSTAR data, we rule against a neutron-star model and conclude that IC 10 X-1 contains a black hole. The eclipse duration of IC 10 X-1 is shorter and its depth shallower at higher energies, an effect consistent with the X-ray emission being obscured during eclipse by a Compton-thick core of a dense wind. The spectrum is strongly disk-dominated, which allows us to constrain the spin of the black hole via X-ray continuum fitting. Three other wind-fed black hole systems are known; the masses and spins of their black holes are high: M˜ 10{--}15{M}⊙ and {a}*\\gt 0.8. If the mass of IC 10 X-1's black hole is comparable, then its spin is likewise high.

  13. Low frequency QPOs and Variable Broad Iron line from LMC X-1

    NASA Astrophysics Data System (ADS)

    Dewangan, G.; Alam, S.; Belloni, T.; Mukherjee, D.; Jhingan, S.

    2014-07-01

    We have performed temporal and energy spectral study of the persistent black hole X-ray binary LMC X-1 using XMM-Newton, Suzaku and RXTE observations. We report the discovery of low frequency (26-56 mHz) QPOs and variable broad iron line from LMC X-1. The QPOs are generally weak with rms amplitudes in the 1-6% range and coherence (quality factor Q˜2-10). The QPOs are accompanied by weak red-noise with rms variability in the 1.3-4% level. The energy spectra of LMC X-1 consist of three components - multicolor disk blackbody (kT˜0.7-0.9 keV), high energy power law tail (photon index ˜2.4-3.3), and broad iron line at 6.4-6.9 keV. The QPOs were detected only in the presence of a strong powerlaw component. The strong broad and relativistic iron line was observed in the presence of both the strong powerlaw and an accretion disk extending to the innermost regions. The iron line is found to be weaker when the disk is truncated and absent when the powerlaw component almost vanished. Our results imply that LMC X-1 does not always remain in the canonical soft state but also transits to the soft intermediate or the steep powerlaw state.

  14. Evidence for a Broad Relativistic Iron Line from the Neutron Star LMXB Ser X-1

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, Sudip; Strohmayer, Tod E.

    2007-01-01

    We report on an analysis of XMM-Newton data from the neutron star low mass X-ray binary (LMXB) Serpens X-1 (Ser X-1). Spectral analysis of EPIC PN data indicates that the previously known broad iron Ka emission line in this source has a significantly skewed structure with a moderately extended red wing. The asymmetric shape of the line is well described with the laor and diskline models in XSPEC, which strongly supports an inner accretion disk origin of the line. To our knowledge this is the first strong evidence for a relativistic line in a neutron star LMXB. This finding suggests that the broad lines seen in other neutron star LMXBs likely originate from the inner disk as well. Detailed study of such lines opens up a new way to probe neutron star parameters and their strong gravitational fields. The laor model describes the line from Ser X-1 somewhat better than diskline, and suggests that the inner accretion disk radius is less than 6GM/c(exp 2). This is consistent with the weak magnetic fields of LMXBs, and may point towards a high compactness and rapid spin of the neutron star. Finally, the inferred source inclination angle in the approximate range 50-60 deg is consistent with the lack of dipping from Ser X-1.

  15. Polarized gamma-ray emission from the galactic black hole Cygnus X-1.

    PubMed

    Laurent, P; Rodriguez, J; Wilms, J; Cadolle Bel, M; Pottschmidt, K; Grinberg, V

    2011-04-22

    Because of their inherently high flux allowing the detection of clear signals, black hole x-ray binaries are interesting candidates for polarization studies, even if no polarization signals have been observed from them before. Such measurements would provide further detailed insight into these sources' emission mechanisms. We measured the polarization of the gamma-ray emission from the black hole binary system Cygnus X-1 with the International Gamma-Ray Astrophysics Laboratory Imager on Board the Integral Satellite (INTEGRAL/IBIS) telescope. Spectral modeling of the data reveals two emission mechanisms: The 250- to 400-keV (kilo-electron volt) data are consistent with emission dominated by Compton scattering on thermal electrons and are weakly polarized. The second spectral component seen in the 400-keV to 2-MeV band is by contrast strongly polarized, revealing that the MeV emission is probably related to the jet first detected in the radio band. PMID:21436402

  16. X-1E on Display Stand at Dryden

    NASA Technical Reports Server (NTRS)

    1988-01-01

    A photo showing the Bell Aircraft Corporation X-1E mounted at a jaunty angle in front of the main building (4800) at NASA Dryden Flight Research Center, Edwards, California. The X-1E began life as the X-1-2, a first generation aircraft. The X-1E flew twenty-six times with two pilots. It was retired on November 6, 1958. There were four versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Supersonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on January 25, 1946. Powered flights began in December 1946. On October 14, 1947, the X-1-1, piloted by Air Force Captain Charles 'Chuck' Yeager, became the first aircraft to exceed the speed of sound, reaching about 700 miles per hour (Mach 1.06) and

  17. On the formation of SMC X-1: The effect of mass and orbital angular momentum loss

    SciTech Connect

    Li, Tao; Li, X.-D. E-mail: lixd@nju.edu.cn

    2014-01-01

    SMC X-1 is a high-mass X-ray binary with an orbital period of 3.9 days. The mass of the neutron star is as low as ∼1M {sub ☉}, suggesting that it was likely formed through an electron-capture supernova rather than an iron-core collapse supernova. From the present system configurations, we argue that the orbital period at the supernova was ≲ 10 days. Since the mass transfer process between the neutron star's progenitor and the companion star before the supernova should have increased the orbital period to tens of days, a mechanism with efficient orbit angular momentum loss and relatively small mass loss is required to account for its current orbital period. We have calculated the evolution of the progenitor binary systems from zero-age main sequence to the pre-supernova stage with different initial parameters and various mass and angular momentum loss mechanisms. Our results show that the outflow from the outer Lagrangian point or a circumbinary disk formed during the mass transfer phase may be qualified for this purpose. We point out that these mechanisms may be popular in binary evolution and significantly affect the formation of compact star binaries.

  18. Real-time operative earthquake forecasting: the case of L'Aquila sequence

    NASA Astrophysics Data System (ADS)

    Marzocchi, W.; Lombardi, A.

    2009-12-01

    A reliable earthquake forecast is one of the fundamental components required for reducing seismic risk. Despite very recent efforts devoted to test the validity of available models, the present skill at forecasting the evolution of seismicity is still largely unknown. The recent Mw 6.3 earthquake - that struck near the city of L'Aquila, Italy on April 6, 2009, causing hundreds of deaths and vast damages - offered to scientists a unique opportunity to test for the first time the forecasting capability in a real-time application. Here, we describe the results of this first prospective experiment. Immediately following the large event, we began producing daily one-day earthquake forecasts for the region, and we provided these forecasts to Civil Protection - the agency responsible for managing the emergency. The forecasts are based on a stochastic model that combines the Gutenberg-Richter distribution of earthquake magnitudes and power-law decay in space and time of triggered earthquakes. The results from the first month following the L'Aquila earthquake exhibit a good fit between forecasts and observations, indicating that accurate earthquake forecasting is now a realistic goal. Our experience with this experiment demonstrates an urgent need for a connection between probabilistic forecasts and decision-making in order to establish - before crises - quantitative and transparent protocols for decision support.

  19. VizieR Online Data Catalog: Deep NIR survey toward Aquila. I. MHOs (Zhang+, 2015)

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Fang, M.; Wang, H.; Sun, J.; Wang, M.; Jiang, Z.; Anathipindika, S.

    2015-11-01

    The observations were conducted in queue-scheduled observing mode between 2012 July 26 and 29 with WIRCam on the Canada-France-Hawaii Telescope (CFHT), covering in total an area of ~1deg2. We observed 10 fields toward the Aquila molecular cloud in the J, H, Ks, and H2 (2.122um) bands. As part of the Gould Belt Legacy program (PID: 30574), the Spitzer Space Telescope observations toward the Serpens-Aquila rift were conducted in 2007 May and September with the IRAC and MIPS cameras. The Herschel archival data used in this paper are part of the Herschel Gould Belt guaranteed time key programs for the study of star formation with the PACS and SPIRE instruments and have been published in Andre et al. (2010A&A...518L.102A), Konyves et al. (2010A&A...518L.106K), and Bontemps et al. (2010A&A...518L..85B). (2 data files).

  20. Mortality in the L'Aquila (Central Italy) Earthquake of 6 April 2009

    PubMed Central

    Alexander, David; Magni, Michele

    2013-01-01

    This paper presents the results of an analysis of data on mortality in the magnitude 6.3 earthquake that struck the central Italian city and province of L'Aquila during the night of 6 April 2009. The aim is to create a profile of the deaths in terms of age, gender, location, behaviour during the tremors, and other aspects. This could help predict the pattern of casualties and priorities for protection in future earthquakes. To establish a basis for analysis, the literature on seismic mortality is surveyed. The conclusions of previous studies are synthesised regarding patterns of mortality, entrapment, survival times, self-protective behaviour, gender and age. These factors are investigated for the data set covering the 308 fatalities in the L'Aquila earthquake, with help from interview data on behavioural factors obtained from 250 survivors. In this data set, there is a strong bias towards victimisation of young people, the elderly and women. Part of this can be explained by geographical factors regarding building performance: the rest of the explanation refers to the vulnerability of the elderly and the relationship between perception and action among female victims, who tend to be more fatalistic than men and thus did not abandon their homes between a major foreshock and the main shock of the earthquake, three hours later. In terms of casualties, earthquakes commonly discriminate against the elderly and women. Age and gender biases need further investigation and should be taken into account in seismic mitigation initiatives. PMID:23326762

  1. First breath of the French seismic crisis committee with the 2009 L’Aquila earthquake

    NASA Astrophysics Data System (ADS)

    Voisin, C.; Delouis, B.; Vergnolle, M. M.; Klinger, Y.; Chiaraluce, L.; Margheriti, L.; Mariscal, A.; Péquégnat, C.; Schlagenhauf, A.; Traversa, P.

    2009-12-01

    The April 2009 L’Aquila earthquake launched the French seismic crisis committee. The mission of this committee is to gather all possible information about the earthquake and the available means for intervention (in terms of human potential and field instruments). These information are passed to the French INSU who decides of and raise fundings for a possible field experiment. The L’Aquila earthquake is the first event to be considered by the committee. French INSU was able to propose to the Italian INGV a set of 4 people and 20 seismic recorders in less than 30h. All stations were deployed over a broad area surrounding the event, in intelligence with the Italian team in 2,5 days. The seismic recorders are Taurus units associated to CMG40 sensors, belonging to SISMOB. They continuously recorded the ground movement, and more than 20,000 events. Data are freely distributed by the French national portal of seismic data Fosfore. They were mixed alltogether with the Italian data in order to perform the relocation of seismicity, and a first attempt to derive a 'noise' correlation tomography. This first attempt of an integrated post-seismic field study should provide the community with useful information in view of a future large event striking the European countries.

  2. Mortality in the l'aquila (central Italy) earthquake of 6 april 2009.

    PubMed

    Alexander, David; Magni, Michele

    2013-01-01

    This paper presents the results of an analysis of data on mortality in the magnitude 6.3 earthquake that struck the central Italian city and province of L'Aquila during the night of 6 April 2009. The aim is to create a profile of the deaths in terms of age, gender, location, behaviour during the tremors, and other aspects. This could help predict the pattern of casualties and priorities for protection in future earthquakes. To establish a basis for analysis, the literature on seismic mortality is surveyed. The conclusions of previous studies are synthesised regarding patterns of mortality, entrapment, survival times, self-protective behaviour, gender and age. These factors are investigated for the data set covering the 308 fatalities in the L'Aquila earthquake, with help from interview data on behavioural factors obtained from 250 survivors. In this data set, there is a strong bias towards victimisation of young people, the elderly and women. Part of this can be explained by geographical factors regarding building performance: the rest of the explanation refers to the vulnerability of the elderly and the relationship between perception and action among female victims, who tend to be more fatalistic than men and thus did not abandon their homes between a major foreshock and the main shock of the earthquake, three hours later. In terms of casualties, earthquakes commonly discriminate against the elderly and women. Age and gender biases need further investigation and should be taken into account in seismic mitigation initiatives. PMID:23326762

  3. The seismicity in the L'Aquila area (Italy) with particular regard to 1985 earthquake

    NASA Astrophysics Data System (ADS)

    Bernardi, Fabrizio; Grazia Ciaccio, Maria; Palombo, Barbara

    2010-05-01

    We study moderate-magnitude earthquakes (Ml ≥3.5) occurred in the Aquila region recorded by the Istituto Nazionale di Geofisica e Vulcanologia from 1981 to 2009 (CSI, Castello et al., 2006 - http://www.ingv.it/CSI/ ; and ISIDe, http://iside.rm.ingv.it/iside/standard/index.jsp) as well as local temporary seismic networks We identify three major sequences (1985, 1994, 1996) occurring before the 6.th April 2009 Mw=6.3 earthquake. The 1985 earthquake (Ml=4.2) is the larger earthquake occurred in the investigated region till April 2009. The 1994 (Ml=3.9) and 1996 (Ml=4.1) occurred in the Campotosto area (NE to L'Aquila). We computed the source moment tensor using surface waves (Giardini et al., 1993) for the main shocks of the 1985 (Mw=4.7) and 1996 (Mw=4.4) sequences. The solutions show normal fault ruptures. We do not find a reliable solution for the major 1994 sequence earthquake. This suggests, that the magnitude of this event is probably below Mw≈4.2, which is the minimum magnitude threshold for this method.

  4. Science, Right and Communication of Risk in L'Aquila trial

    NASA Astrophysics Data System (ADS)

    Altamura, Marco; Miozzo, Davide; Boni, Giorgio; Amato, Davide; Ferraris, Luca; Siccardi, Franco

    2013-04-01

    CIMA Research Foundation has had access to all the information of the criminal trial held in l'Aquila intended against some of the members of the Commissione Nazionale Grandi Rischi (National Commission for Forecasting and Preventing Major Risks) and some directors of the Italian Civil Protection Department. These information constitute the base of a study that has examined: - the initiation of investigations by the families of the victims; - the public prosecutor's indictment; - the testimonies; - the liaison between experts in seismology social scientists and communication; - the statement of the defence; - the first instance decision of condemnation. The study reveals the paramount importance of communication of risk as element of prevention. Taken into particular account is the method of the Judicial Authority ex-post control on the evaluations and decisions of persons with a role of decision maker within the Civil Protection system. In the judgment just published by the Court of l'Aquila, the reassuring information from scientists and operators of Civil Protection appears to be considered as a negative value.

  5. Adaptive Response of Children and Adolescents with Autism to the 2009 Earthquake in L'Aquila, Italy

    ERIC Educational Resources Information Center

    Valenti, Marco; Ciprietti, Tiziana; Di Egidio, Claudia; Gabrielli, Maura; Masedu, Francesco; Tomassini, Anna Rita; Sorge, Germana

    2012-01-01

    The literature offers no descriptions of the adaptive outcomes of people with autism spectrum disorder (ASD) after natural disasters. Aim of this study was to evaluate the adaptive behaviour of participants with ASD followed for 1 year after their exposure to the 2009 earthquake in L'Aquila (Italy) compared with an unexposed peer group with ASD,…

  6. X-1-2 with Pilots Robert Champine Herb Hoover

    NASA Technical Reports Server (NTRS)

    1949-01-01

    The Bell Aircraft Corporation X-1-2 and two of the NACA pilots that flew the aircraft. The one on the left is Robert Champine with the other being Herbert Hoover. The X-1-2 was also equipped with the 10-percent wing and 8 percent tail, powered with an XLR-11 rocket engine and aircraft made its first powered flight on December 9, 1946 with Chalmers 'Slick' Goodlin at the controls. As with the X-1-1 the X-1-2 continued to investigate transonic/supersonic flight regime. NACA pilot Herbert Hoover became the first civilian to fly Mach 1, March 10, 1948. X-1-2 flew until October 23, 1951, completing 74 glide and powered flights with nine different pilots, when it was retired to be rebuilt as the X-1E.

  7. THE EXTREME SPIN OF THE BLACK HOLE IN CYGNUS X-1

    SciTech Connect

    Gou Lijun; McClintock, Jeffrey E.; Reid, Mark J.; Steiner, James F.; Narayan, Ramesh; Xiang, Jingen; Orosz, Jerome A.; Remillard, Ronald A.; Arnaud, Keith A.; Davis, Shane W.

    2011-12-01

    The compact primary in the X-ray binary Cygnus X-1 was the first black hole to be established via dynamical observations. We have recently determined accurate values for its mass and distance, and for the orbital inclination angle of the binary. Building on these results, which are based on our favored (asynchronous) dynamical model, we have measured the radius of the inner edge of the black hole's accretion disk by fitting its thermal continuum spectrum to a fully relativistic model of a thin accretion disk. Assuming that the spin axis of the black hole is aligned with the orbital angular momentum vector, we have determined that Cygnus X-1 contains a near-extreme Kerr black hole with a spin parameter a{sub *} > 0.95 (3{sigma}). For a less probable (synchronous) dynamical model, we find a{sub *} > 0.92 (3{sigma}). In our analysis, we include the uncertainties in black hole mass, orbital inclination angle, and distance, and we also include the uncertainty in the calibration of the absolute flux via the Crab. These four sources of uncertainty totally dominate the error budget. The uncertainties introduced by the thin-disk model we employ are particularly small in this case given the extreme spin of the black hole and the disk's low luminosity.

  8. A dark jet dominates the power output of the stellar black hole Cygnus X-1.

    PubMed

    Gallo, Elena; Fender, Rob; Kaiser, Christian; Russell, David; Morganti, Raffaella; Oosterloo, Tom; Heinz, Sebastian

    2005-08-11

    Black holes undergoing accretion are thought to emit the bulk of their power in the X-ray band by releasing the gravitational potential energy of the infalling matter. At the same time, they are capable of producing highly collimated jets of energy and particles flowing out of the system with relativistic velocities. Here we show that the 10-solar-mass (10M(o)) black hole in the X-ray binary Cygnus X-1 (refs 3-5) is surrounded by a large-scale (approximately 5 pc in diameter) ring-like structure that appears to be inflated by the inner radio jet. We estimate that in order to sustain the observed emission of the ring, the jet of Cygnus X-1 has to carry a kinetic power that can be as high as the bolometric X-ray luminosity of the binary system. This result may imply that low-luminosity stellar-mass black holes as a whole dissipate the bulk of the liberated accretion power in the form of 'dark', radiatively inefficient relativistic outflows, rather than locally in the X-ray-emitting inflow. PMID:16094361

  9. The Extreme Spin of the Black Hole in Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Gou, Lijun; McClintock, Jeffrey E.; Reid, Mark J.; Orosz, Jerome A.; Steiner, James F.; Narayan, Ramesh; Xiang, Jingen; Remillard, Ronald A.; Arnaud, Keith A.; Davis, Shane W.

    2011-01-01

    The compact primary in the X-ray binary Cygnus X-1 was the first black hole to be established via dynamical observations. We have recently determined accurate values for its mass and distance, and for the orbital inclination angle of the binary. Building on these results, which are based on our favored (asynchronous) dynamical model, we have measured the radius of the inner edge of the black hole s accretion disk by fitting its thermal continuum spectrum to a fully relativistic model of a thin accretion disk. Assuming that the spin axis of the black hole is aligned with the orbital angular momentum vector, we have determined that Cygnus X-1 contains a near-extreme Kerr black hole with a spin parameter a* > 0.95 (3(sigma)). For a less probable (synchronous) dynamical model, we find a. > 0.92 (3 ). In our analysis, we include the uncertainties in black hole mass, orbital inclination angle, and distance, and we also include the uncertainty in the calibration of the absolute flux via the Crab. These four sources of uncertainty totally dominate the error budget. The uncertainties introduced by the thin-disk model we employ are particularly small in this case given the extreme spin of the black hole and the disk s low luminosity.

  10. X-1-2 on Ramp with Boeing B-29

    NASA Technical Reports Server (NTRS)

    1949-01-01

    The Bell Aircraft Corporation X-1-2 sitting on the ramp at NACA High- Speed Flight Research Station with the Boeing B-29 launch ship behind. The B-29 was fondly referred to as 'Fertile Myrtle.' The painting near the nose depicts a stork carrying a bundle which is symbolic of the Mothership launching her babe (X-1-2). The pilot access door is open to the cockpit of the X-1-2 aircraft.

  11. [The new territorial configuration of L'Aquila (Central Italy) after the 2009 earthquake and places and behaviours changes of everyday life].

    PubMed

    Castellani, Serena; Palma, Francesca; Calandra, Lina Maria

    2016-01-01

    Since 2010, the Cartolab Laboratory research team (Department of Human Studies, University of L'Aquila) has been investigating the social geography in the post-earthquake period through the analysis of the territorial changes and new sociospatial configurations occurred in the everyday life of the L'Aquila inhabitants. Accordingly, this paper aims to describe the principal results of researches concentrating on the use of leisure time and leisure places in the post-disaster period in L'Aquila. The paper uses an action-research/participating- participatory (RAPP) methodology. The paper presents the monitored changes occurred in leisure time and places, and compares them with the conditions before the earthquake. Primary data have been retrieved by surveys and interviews. Results indicate that acceleration of fragmentation and dispersion of inhabitants are the main characteristics of the new sociospatial configuration in the post-disaster period in L'Aquila. PMID:27291215

  12. The Complete ``Z'' Track of Circinus X-1

    NASA Astrophysics Data System (ADS)

    Shirey, Robert E.; Bradt, Hale V.; Levine, Alan M.

    1999-05-01

    We carried out an extensive Rossi X-Ray Timing Explorer campaign, in 1997 June, to study Circinus X-1 during the active portion of its 16.55 day intensity cycle. The observations spanned 10 days, including 56% coverage for 7 days, and allowed us to find time segments that clearly demonstrate continuous evolution along the horizontal, normal, and flaring branches (HB/NB/FB) of a Z-source low-mass X-ray binary. These results confirm and extend the behavior we inferred from earlier observations. Here we study the continuous evolution of the Fourier power spectra and the energy spectra around the complete hardness-intensity track. A narrow quasi-periodic oscillation (QPO) peak, previously observed in the power spectra at 1.3-32 Hz, increases in frequency from 12 Hz to 25 Hz moving down a vertical extension of the horizontal branch in the hardness-intensity diagram. These horizontal branch QPOs (HBOs) occur near 30 Hz and fade in strength on the horizontal portion of the HB, while a broad peak in the power spectrum arises near 4 Hz. This peak becomes much more prominent along the normal branch and remains near 4 Hz (the normal branch QPOs, or NBOs). On the flaring branch, neither QPO is present and the power spectrum is dominated by very low frequency noise. We also found that each branch of the spectral track is associated with a specific type of evolution of the energy spectrum. We explored various models for the energy spectrum and parameterized the evolution of the spectrum in terms of a two-component model consisting of a multitemperature ``disk blackbody'' and a higher temperature (~2 keV) blackbody. We also show that an unusual line- or edgelike feature occurs at about 10 keV in energy spectra from the flaring branch and lower normal branch. This unusual feature is very similar to one seen on the FB and lower NB of the Z source GX 5-1.

  13. Stress drop and source scaling of the 2009 April L'Aquila earthquakes

    NASA Astrophysics Data System (ADS)

    Calderoni, Giovanna; Rovelli, Antonio; Singh, Shri Krishna

    2013-01-01

    The empirical Green's function (EGF) technique is applied in the frequency domain to 962 broad-band seismograms (3.3 ≤ MW ≤ 6.1) to determine stress drop and source scaling of the 2009 April L'Aquila earthquakes. The station distance varies in the range 100-250 km from the source. Ground motions of several L'Aquila earthquakes are characterized by large azimuthal variations due to source directivity, even at low magnitudes. Thus, the individual-station stress-drop estimates are significantly biased when source directivity is not taken into account properly. To reduce the bias, we use single-station spectral ratios with pairs of earthquakes showing a similar degree of source directivity. The superiority of constant versus varying stress-drop models is assessed through minimization of misfit in a least-mean-square sense. For this analysis, seismograms of 26 earthquakes occurring within 10 km from the hypocentres of the three strongest shocks are used. We find that a source model where stress drop increases with the earthquake size has the minimum misfit: as compared to the best constant stress-drop model the improvement in the fit is of the order of 40 per cent. We also estimate the stress-drop scaling on a larger data set of 64 earthquakes, all of them having an independent estimate of seismic moment and consistent focal mechanism. An earthquake which shows no directivity is chosen as EGF event. This analysis confirms the former trend and yields individual-event stress drops very close to 10 MPa at magnitudes MW > 4.5 that decrease to 1 MPa, on the average, at the smallest magnitudes. A varying stress-drop scaling of L'Aquila earthquakes is consistent with results from other studies using EGF techniques but contrasts with results of authors that used inversion techniques to separate source from site and propagation effects. We find that there is a systematic difference for small events between the results of the two methods, with lower and less scattered values

  14. On-line continuous monitoring of groundwater radon levels at L’Aquila fault, Italy

    NASA Astrophysics Data System (ADS)

    Tsabaris, C.; Lampousis, A.

    2009-12-01

    This work describes in situ radon progeny measurements in the Gran Sasso National Laboratory (LNGS) of L’Aquila region, located 60 miles north-east of Rome, Italy, conducted in December 2007. The marine radon progeny monitor KATERINA (i.e., Hellenic Centre for Marine Research patent July 2008) was submerged inside a tank filled with groundwater from the Gran Sasso Mountain. The measured spectra obtained through KATERINA exhibited photopeaks of the main gamma emitters (214Pb and 214Bi) of the primordial nucleus 238U (222Rn). High background levels of radionuclides (i.e., inside the mountain) emitting high energy gamma rays affected the measurement. In order to correct and deduce the final volumetric activities of radon progenies (214Pb and 214Bi) the system was calibrated using the simulation tool GEANT4. The first day of deployment an averaged value of radon progenies amounted to a value of (3.1 ± 0.3) Bq/l. The second day the averaged values of radon progenies were reduced by 30% due to the loss of noble gas radon from the tank. Additional spectra were recorded successfully after removing background airborne radon present in the LNGS laboratory. KATERINA operated reliably during its in situ radon monitoring. This was confirmed by further calibration using off line measurements performed in collaboration with the Marine Environmental Laboratory of the International Atomic Energy Agency (IAEA). Future work includes the development of a continuous radon monitoring tool to further study the L’Aquila fault. By implementing a continuous inflow and outflow system and by controlling the radon levels both inside and outside the water tank, radon variations will be correlated with other geophysical/geochemical parameters like microseismicity, slip rates, pH, H2S, CO2, and He. Additional contributions include an increased understanding of the correlations between radon levels in the proximity of active faults and regional seismic activity. If indeed this proves to be an

  15. X-Ray Variation Statistics and Wind Clumping in Vela X-1

    NASA Technical Reports Server (NTRS)

    Furst, Felix; Kreykenbohm, Ingo; Pottschmidt, Katja; Wilms, Joern; Hanke, Manfred; Rothschild, Richard E.; Kretschmar, Peter; Schulz, Norbert S.; Huenemoerder, David P.; Klochkov, Dmitry; Staubert, Rudiger

    2010-01-01

    We investigate the structure of the wind in the neutron star X-ray binary system Vela X-1 by analyzing its flaring behavior. Vela X-1 shows constant flaring, with some flares reaching fluxes of more than 3.0 Crab between 20-60 keV for several 100 seconds, while the average flux is around 250 mCrab. We analyzed all archival INTEGRAL data, calculating the brightness distribution in the 20-60 keV band, which, as we show, closely follows a log-normal distribution. Orbital resolved analysis shows that the structure is strongly variable, explainable by shocks and a fluctuating accretion wake. Analysis of RXTE ASM data suggests a strong orbital change of N. Accreted clump masses derived from the INTEGRAL data are on the order of 5 x 10(exp 19)-10(exp 21) g. We show that the lightcurve can be described with a model of multiplicative random numbers. In the course of the simulation we calculate the power spectral density of the system in the 20-100 keV energy band and show that it follows a red-noise power law. We suggest that a mixture of a clumpy wind, shocks, and turbulence can explain the measured mass distribution. As the recently discovered class of supergiant fast X-ray transients (SFXT) seems to show the same parameters for the wind, the link between persistent HMXB like Vela X-1 and SFXT is further strengthened.

  16. Kilohertz Quasi-Periodic Oscillation Peak Separation Is Not Constant in Scorpius X-1

    NASA Astrophysics Data System (ADS)

    van der Klis, Michiel; Wijnands, Rudy A. D.; Horne, Keith; Chen, Wan

    1997-06-01

    We report on a series of 20, ~105 counts s-1, 0.125 ms time-resolution Rossi X-Ray Timing Explorer observations of the Z-source and low-mass X-ray binary Scorpius X-1. Twin kilohertz quasi-periodic oscillation (QPO) peaks are obvious in nearly all observations. We find that the peak separation is not constant, as expected in some beat-frequency models, but instead varies from ~310 to ~230 Hz when the centroid frequency of the higher frequency peak varies from ~875 to ~1085 Hz. We detect none of the additional QPO peaks at higher frequencies predicted in the photon bubble model (PBM), with best-case upper limits on the peaks' power ratio of 0.025. We do detect, simultaneously with the kilohertz QPO, additional QPO peaks near 45 and 90 Hz whose frequency increases with mass accretion rate. We interpret these as first and second harmonics of the so-called horizontal-branch oscillations that are well known from other Z-sources and usually interpreted in terms of the magnetospheric beat-frequency model (BFM). We conclude that the magnetospheric BFM and the PBM are now unlikely to explain the kilohertz QPO in Sco X-1. In order to succeed in doing so, any BFM involving the neutron star spin (unseen in Sco X-1) will have to postulate at least one additional unseen frequency, beating with the spin to produce one of the kilohertz peaks.

  17. GBM Monitoring of Cyg X-1 During the Recent State Transitions

    NASA Astrophysics Data System (ADS)

    Case, Gary L., II; Baldridge, S.; Cherry, M.; Camero-Arranz, A.; Finger, M.; Chaplin, V.; Jenke, P.; Wilson-Hodge, C.

    2011-09-01

    Cygnus X-1 is a high-mass x-ray binary with a black hole compact object. It is normally extremely bright in hard x-rays and low energy gamma rays and resides in the canonical hard spectral state. In July 2010, however, Cyg X-1 made a transition to the soft state, with a rise in the soft x-ray flux and a decrease in the flux in the hard x-ray and low energy gamma-ray energy bands. It remained in the soft state until April 2011 when it made the transition back to the hard state. We have been using the Gamma-Ray Burst Monitor on Fermi to monitor the fluxes of a number of sources, including Cyg X-1, in the 8-1000 keV energy range using the Earth occultation technique. We present light curves showing the decrease in the hard x-ray and low energy gamma-ray energy range during the hard-to-soft state transition, the several broad flares observed in these higher energies during the soft state, and then the transition back to the hard state. We also present preliminary spectra based on GBM data for the initial hard state, the spectral evolution to the soft state, and the spectral evolution back to the hard state. The implication of these results on the physical processes responsible for the hard x-ray and low energy gamma-ray emission will be discussed.

  18. How to predict Italy L'Aquila M6.3 earthquake

    NASA Astrophysics Data System (ADS)

    Guo, Guangmeng

    2016-04-01

    According to the satellite cloud anomaly appeared over eastern Italy on 21-23 April 2012, we predicted the M6.0 quake occurred in north Italy successfully. Here checked the satellite images in 2011-2013 in Italy, and 21 cloud anomalies were found. Their possible correlation with earthquakes bigger than M4.7 which located in Italy main fault systems was statistically examined by assuming various lead times. The result shows that when the leading time interval is set to 23≤ΔT≤45 days, 8 of the 10 quakes were preceded by cloud anomalies. Poisson random test shows that AAR (anomaly appearance rate) and EOR (EQ occurrence rate) is much higher than the values by chance. This study proved the relation between cloud anomaly and earthquake in Italy. With this method, we found that L'Aquila earthquake can also be predicted according to cloud anomaly.

  19. Evidence of underground electric current generation during the 2009 L'Aquila earthquake: Real or instrumental?

    NASA Astrophysics Data System (ADS)

    Masci, F.; Thomas, J. N.

    2016-06-01

    We investigate magnetic effects in correspondence of the Mw6.1 L'Aquila earthquake. Magnetic and seismic records are analyzed. Rapid and distinct changes and an offset can be seen in magnetic field components after the main shock. We show that these effects result from electromagnetic induction due to the movement of the sensors through the Earth's magnetic field and from a permanent displacement of the sensors from their original position caused by the passing seismic waves. A transient signal in total field data from an overhauser magnetometer apparently occurs in correspondence with the earthquake. Our analysis shows that the transient was not observed by other sensors that were operating in close proximity to the overhauser. Thus, the transient signal in the total magnetic field data, and the offset in the magnetic field components, cannot be associated with a hypothetical underground electric current generated by the earthquake, as suggested by Nenovski (2015).

  20. The 2009 L'Aquila sequence (Central Italy): fault system anatomy by aftershock distribution.

    NASA Astrophysics Data System (ADS)

    Chiaraluce, Lauro

    2010-05-01

    On April 6 (01:32 UTC) 2009 a destructive MW 6.13 earthquake struck the Abruzzi region in Central Italy, causing nearly 300 deaths, 40.000 homeless people and strong damage to the cultural heritage of the L'Aquila city and its province. Two strong earthquakes hit the same area in historical times (e.g. the 1461 and 1703 events), but the main fault that drives the extension in this portion of the Apennines was unknown. Seismic data was recorded at both permanent stations of the Centralised Italian National Seismic Network managed by the INGV and 45 temporary stations installed in the epicentral area together with the LGIT of Grenoble (Fr). The resulting geometry of the dense monitoring network allows us to gain very high resolution earthquake locations that we use to investigate the geometry of the activated fault system and to report on seismicity pattern and kinematics of the whole sequence. The mainshock was preceded by a foreshock sequence that activated the main fault plane during the three months before, while the largest foreshock (MW 4.08) occurred one week before (30th of March) nucleated on a antithetic (e.g. off-fault) segment. The distribution of the aftershocks defines a complex, 50 km long, NW-trending normal fault system, with seismicity nucleating within the upper 10-12 km of the crust. There is an exception of an event (MW 5.42) nucleating a couple of kilometers deeper that the 7th of April that activates a high angle normal fault antithetic to the main system. Its role is still unclear. We reconstruct the geometry of the two major SW-dipping normal faults forming a right lateral en-echelon system. The main fault (L'Aquila fault) is activated by the 6th of April mainshock unluckily located right below the city of L'Aquila. A 50°SW-dipping plane with planar geometry about 16 km long. The related seismicity interests the entire first 12 km of the upper crust from the surface. The ground surveys carried out soon after the occurrence of the earthquake

  1. Spatial structure in the diet of imperial eagles Aquila heliaca in Kazakhstan

    USGS Publications Warehouse

    Katzner, T.E.; Bragin, E.A.; Knick, S.T.; Smith, A.T.

    2006-01-01

    We evaluated the relationship between spatial variability in prey and food habits of eastern imperial eagles Aquila heliaca at a 90,000 ha national nature reserve in north-central Kazakhstan. Eagle diet varied greatly within the population and the spatial structure of eagle diet within the population varied according to the scale of measurement. Patterns in dietary response were inconsistent with expectations if either ontogenetic imprinting or competition determined diet choice, but they met expectations if functional response determined diet. Eagles nesting near a high-density prey resource used that resource almost exclusively. In contrast, in locations with no single high-density prey species, eagles' diet was more diverse. Our results demonstrate that spatial structuring of diet of vertebrate predators can provide important insight into the mechanisms that drive dietary decisions. ?? OIKOS.

  2. The detection of a companion star to the Cepheid variable Eta Aquilae

    NASA Technical Reports Server (NTRS)

    Mariska, J. T.; Doschek, G. A.; Feldman, U.

    1980-01-01

    Ultraviolet spectra have been obtained with IUE of the classical Cepheid Eta Aquilae at several phases in the 7.18 day period. Significant ultraviolet emission is detected at wavelengths less than 1600 A, where little flux is expected from classical Cepheids. Furthermore, the emission at wavelengths less than about 1600 A does not vary with phase. Comparison with model atmosphere flux distributions shows that the nonvariable emission is consistent with the flux expected from a main-sequence companion star with an effective temperature of about 9500 K (A0 V). The observed ultraviolet flux and spectral type are used to compute a distance of 300 pc to the system, in agreement with the distance predicted using the period luminosity relation.

  3. Annual movements of a steppe eagle (Aquila nipalensis) summering in Mongolia and wintering in Tibet

    USGS Publications Warehouse

    Ellis, D.H.; Moon, S.L.; Robinson, J.W.

    2001-01-01

    An adult female steppe eagle (Aquila nipalensis Hodgson) was captured and fitted with a satellite transmitter in June 1995 in southeastern Mongolia. In fall, it traveled southwest towards India as expected, but stopped in southeastern Tibet and wintered in a restricted zone within the breeding range of the steppe eagle. In spring, the bird returned to the same area of Mongolia where it was captured. These observations, though derived from the movements of a single bird, suggest three things that are contrary to what is generally believed about steppe eagle biology. First, not all steppe eagles move to warmer climes in winter. Second, not all steppe eagles are nomadic in winter. Finally, because our bird wintered at the periphery of the steppe eagle breeding range in Tibet, perhaps birds that breed in this same area also winter there. If so, not all steppe eagles are migratory.

  4. Long term X-ray variability of Circinus X-1

    SciTech Connect

    Saz Parkinson, Pablo

    2003-03-19

    We present an analysis of long term X-ray monitoring observations of Circinus X-1 (Cir X-1) made with four different instruments: Vela 5B, Ariel V ASM, Ginga ASM, and RXTE ASM, over the course of more than 30 years. We use Lomb-Scargle periodograms to search for the {approx}16.5 day orbital period of Cir X-1 in each of these data sets and from this derive a new orbital ephemeris based solely on X-ray measurements, which we compare to the previous ephemerides obtained from radio observations. We also use the Phase Dispersion Minimization (PDM) technique, as well as FFT analysis, to verify the periods obtained from periodograms. We obtain dynamic periodograms (both Lomb-Scargle and PDM) of Cir X-1 during the RXTE era, showing the period evolution of Cir X-1, and also displaying some unexplained discrete jumps in the location of the peak power.

  5. X-1-2 on ramp with Boeing B-29

    NASA Technical Reports Server (NTRS)

    1949-01-01

    The Bell Aircraft Corporation X-1-2 Sitting on the ramp at NACA High-Speed Flight Research Station with the Boeing B-29 launch ship behind. The painting near the nose of the B-29 depicts a stork carrying a bundle which is symbolic of the Mothership launching her babe (X-1-2). The pilot access door is open to the cockpit of the X-1-2 aircraft. On the X-1-2's fin is the old NACA shield, which was later replaced with a yellow band and the letters 'NACA' plus wings that were both black. There were four versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on Jan. 25, 1946. Powered flights began in December 1946. On Oct. 14, 1947, the X-1

  6. X-1E on Lakebed with Collapsed Nose Gear

    NASA Technical Reports Server (NTRS)

    1956-01-01

    This photo was taken June 18, 1956 on Rogers Dry Lakebed after Flight 7 of the Bell Aircraft Corporation X-1E with NACA High-Speed Flight Station test pilot Joseph `Joe' Walker at the controls. The first generation X-1s were well known for nose gear failures and the X-1E was no exception. The hard pitch down on landing usually resulted in a collapsed nose gear. The damage rarely was serious but required several days of down-time for repair. The X-1E was the only one to have a true tail skid to protect the empennage from over-rotation during landing. There were four versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Supersonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on January 25

  7. A Multiyear Light Curve of Scorpius X-1 Based on Compton Gamma Ray Observatory BATSE Spectroscopy Detector Observations

    NASA Astrophysics Data System (ADS)

    McNamara, B. J.; Harrison, T. E.; Mason, P. A.; Templeton, M.; Heikkila, C. W.; Buckley, T.; Galvan, E.; Silva, A.; Harmon, B. A.

    1998-06-01

    A multiyear light curve of the low mass X-ray binary, Scorpius X-1, is constructed based on the Compton Gamma Ray Observatory Burst and Transient Source Experiment (BATSE) Spectroscopy Detector (SD) data in the nominal energy range of 10-20 keV. A detailed discussion is given of the reduction process of the BATSE/SD data. Corrections to the SD measurements are made for off-axis pointings, spectral and bandpass changes, and differences in the eight SD sensitivities. The resulting 4.4 yr Sco X-1 SD light curve is characterized in terms of the timescales over which various types of emission changes occur. This light curve is then compared with Sco X-1 light curves obtained by Ariel 5, the BATSE Large Area Detectors (LADs), and the RXTE all-sky monitor (ASM). Coincident temporal coverage by the BATSE/SD and RXTE/ASM allows a direct comparison of the behavior of Sco X-1 over a range of high energies to be made. These ASM light curves are then used to discuss model constraints on the Sco X-1 system.

  8. A Multi-Year Light Curve of Scorpius X-1 Based on CGRO BATSE Spectroscopy Detector Observations

    NASA Technical Reports Server (NTRS)

    McNamara, B. J.; Harrison, T. E.; Mason, P. A.; Templeton, M.; Heikkila, C. W.; Buckley, T.; Galvan, E.; Silva, A.; Harmon, B. A.

    1998-01-01

    A multi-year light curve of the low mass X-ray binary, Scorpius X-1, is constructed based on the Compton Gamma-ray Observatory (CGRO) Burst and Transient Source Experiment (BATSE) Spectroscopy Detector (SD) data in the nominal energy range of 10-20 keV. A detailed discussion is given of the reduction process of the BATSE/SD data. Corrections to the SD measurements are made for off-axis pointings, spectral and bandpass changes, and differences in the eight SD sensitivities. The resulting 4.4 year Sco X-1 SD light curve is characterized in terms of the time scales over which various types of emission changes occur. This light curve is then compared with Sco X-1 light curves obtained by Axiel 5, the BATSE Large Area Detectors (LADs), and the RXTE all-sky monitor (ASM). Coincident temporal coverage by the BATSE/SD and RXTE/ASM allows a direct comparison of the behavior of Sco X-1 over a range of high energies to be made. These ASM light curves are then used to discuss model constraints on the Sco X-1 system.

  9. Aspects on the origin of the precursory magnetic anomalies of the Mw 6.4 Aquila earthquake

    NASA Astrophysics Data System (ADS)

    Dologlou, Elizabeth

    2014-03-01

    An anomalous behaviour of the scaling exponent derived from the detrended fluctuation analysis (DFA) of the time series of low frequency variations of the horizontal and vertical magnetic field components has been recently reported as being observed 2 months prior to the Mw 6.3 earthquake on 6 April 2009, close to L'Aquila city, Italy. Here, we suggest a possible physical explanation of this effect based on the experience from similar measurements in Greece. In particular, for example, we compare these observations associated with Aquila earthquake with the ones of the Mw 6.6 earthquake on 13 May 1995 at Kozani-Grevena, Greece where both magnetic field variations and seismic electric signals (SES) were recorded. Almost 1 month before the latter earthquake, anomalous variations in both electric and magnetic field were detected, the time series of that were analysed by means of DFA and led to an exponent close to unity. Similarly, the calculated DFA exponent for the Aquila earthquake time series of the anomalous magnetic field variations 2 months before the main shock was also found close to unity. These results could imply that in the case of Aquila, according to the Maxwell's laws, one should expect to observe simultaneously with the magnetic signal an associated SES activity, provided that an appropriate station to monitoring the earth's electric field variations in the same area was available. Hence, it seems that similar underlying non-linear dynamic processes in mechanical and as well as electromagnetic sense, with features of criticality, dominated in both pre-focal areas.

  10. GAMMA-RAY OBSERVATIONS OF CYGNUS X-1 ABOVE 100 MeV IN THE HARD AND SOFT STATES

    SciTech Connect

    Sabatini, S.; Tavani, M.; Del Santo, M.; Campana, R.; Evangelista, Y.; Piano, G.; Del Monte, E.; Giusti, M.; Striani, E.; Pooley, G.; Chen, A.; Giuliani, A.; Colafrancesco, S.; Longo, F.; Morselli, A.; Pellizzoni, A.; Pilia, M.; and others

    2013-04-01

    We present the results of multi-year gamma-ray observations by the AGILE satellite of the black hole binary system Cygnus X-1. In a previous investigation we focused on gamma-ray observations of Cygnus X-1 in the hard state during the period mid-2007/2009. Here we present the results of the gamma-ray monitoring of Cygnus X-1 during the period 2010/mid-2012 which includes a remarkably prolonged 'soft state' phase (2010 June-2011 May). Previous 1-10 MeV observations of Cyg X-1 in this state hinted at a possible existence of a non-thermal particle component with substantial modifications of the Comptonized emission from the inner accretion disk. Our AGILE data, averaged over the mid-2010/mid-2011 soft state of Cygnus X-1, provide a significant upper limit for gamma-ray emission above 100 MeV of F{sub soft} < 20 Multiplication-Sign 10{sup -8} photons cm{sup -2} s{sup -1} , excluding the existence of prominent non-thermal emission above 100 MeV during the soft state of Cygnus X-1. We discuss theoretical implications of our findings in the context of high-energy emission models of black hole accretion. We also discuss possible gamma-ray flares detected by AGILE. In addition to a previously reported episode observed by AGILE in 2009 October during the hard state, we report a weak but important candidate for enhanced emission which occurred at the end of 2010 June (2010 June 30 10:00-2010 July 2 10:00 UT) exactly coinciding with a hard-to-soft state transition and before an anomalous radio flare. An appendix summarizes all previous high-energy observations and possible detections of Cygnus X-1 above 1 MeV.

  11. X-1-2 on ramp during ground engine test

    NASA Technical Reports Server (NTRS)

    1947-01-01

    Ground engine test run on the Bell Aircraft Corporation X-1-2 airplane at NACA Muroc Flight Test Unit service area. Notice the front on the lower part of the aircraft aft of the nose section. The frost forms from the mixture of the propellants (including liquid oxygen) in the internal tanks. This photograph was taken in 1947. The aircraft shown is still painted in its original saffron (orange) paint finish. This was later changed to white, which was more visible against the dark blue sky than saffron turned out to be. There were four versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on Jan. 25, 1946. Powered flights began in December

  12. Well-being and perceived quality of life in elderly people displaced after the earthquake in L'Aquila, Italy.

    PubMed

    Giuliani, Anna Rita; Mattei, Antonella; Santilli, Flavio; Clori, Giovanna; Scatigna, Maria; Fabiani, Leila

    2014-06-01

    On 6 April 2009, the city of L'Aquila was hit by a violent earthquake that destroyed almost all of its medieval centre, and the surviving inhabitants were evacuated and relocated in temporary quarters or undamaged homes. The aim of this study was to investigate the perceived quality of life of the elderly population 3 years after the earthquake in relation to the social and logistic issues of new housing. The study was carried out between October 2011 and March 2012, and involved 571 subjects aged over 65 years living in the municipality of L'Aquila. The interviews took place in the surgeries of general practitioners and the city's Department of Prevention and Vaccination in the anti-influenza immunisation period. The instrument used was a 36-item questionnaire with closed, multiple choice answers divided into the following sections: demographics, everyday activities, health and perceived health, and the quality of life in the city. The results show that, 3 years after the earthquake, the elderly population living in the new towns and temporary housing of L'Aquila have a worse perception of their quality of life than the others. They feel a certain social isolation and wish to live elsewhere. Governments faced with the problems arising from a natural calamity should take into account all of the elements making up a good quality of life and, before making choices whose impact cannot be changed, consider both their immediate and long-term social consequences. PMID:24302517

  13. Palaeoseismology of the L'Aquila faults (central Italy, 2009, Mw 6.3 earthquake): implications for active fault linkage

    NASA Astrophysics Data System (ADS)

    Galli, Paolo A. C.; Giaccio, Biagio; Messina, Paolo; Peronace, Edoardo; Zuppi, Giovanni Maria

    2011-12-01

    Urgent urban-planning problems related to the 2009 April, Mw 6.3, L'Aquila earthquake prompted immediate excavation of palaeoseismological trenches across the active faults bordering the Aterno river valley; namely, the Mt. Marine, Mt. Pettino and Paganica faults. Cross-cutting correlations amongst existing and new trenches that were strengthened by radiocarbon ages and archaeological constraints show unambiguously that these three investigated structures have been active since the Last Glacial Maximum period, as seen by the metric offset that affected the whole slope/alluvial sedimentary succession up to the historical deposits. Moreover, in agreement with both 18th century accounts and previous palaeoseismological data, we can affirm now that these faults were responsible for the catastrophic 1703 February 2, earthquake (Mw 6.7). The data indicate that the Paganica-San Demetrio fault system has ruptured in the past both together with the conterminous Mt. Pettino-Mt. Marine fault system, along more than 30 km and causing an Mw 6.7 earthquake, and on its own, along ca. 19 km, as in the recent 2009 event and in the similar 1461 AD event. This behaviour of the L'Aquila faults has important implications in terms of seismic hazard assessment, while it also casts new light on the ongoing fault linkage processes amongst these L'Aquila faults.

  14. Incertitude in disaster sciences and scientists' responsibilities: A case study of the L'Aquila earthquake trial

    NASA Astrophysics Data System (ADS)

    Koketsu, Kazuki; Oki, Satoko

    2015-04-01

    What disaster sciences are expected by the society is to prevent or mitigate future natural disasters, and therefore it is necessary to foresee natural disasters. However, various constraints often make the foreseeing difficult so that there is a high incertitude in the social contribution of disaster sciences. If scientists overstep this limitation, they will be held even criminally responsible. The L'Aquila trial in Italy is such a recent example and so we have performed data collections, hearing investigations, analyses of the reasons for the initial court's judgment, etc., to explore the incertitude of disaster sciences and scientists' responsibilities. As a result, we concluded that the casualties during the L'Aquila earthquake were mainly due to a careless "safety declaration" by the vice-director of the Civil Protection Agency, where the incertitude of disaster sciences had never been considered. In addition, news media which reported only this "safety declaration" were also seriously responsible for the casualties. The accused other than the vice-director were only morally responsible, because their meeting remarks included poor risk communication in disaster sciences but those were not reported to the citizens in advance to the L'Aquila earthquake. In the presentation, we will also discuss the similarities and differences between our conclusions above and the reasons for the appeals court's judgement, which will be published in February.

  15. Geosphere coupling and hydrothermal anomalies before the 2009 Mw 6.3 L'Aquila earthquake in Italy

    NASA Astrophysics Data System (ADS)

    Wu, Lixin; Zheng, Shuo; De Santis, Angelo; Qin, Kai; Di Mauro, Rosa; Liu, Shanjun; Rainone, Mario Luigi

    2016-08-01

    The earthquake anomalies associated with the 6 April 2009 Mw 6.3 L'Aquila earthquake have been widely reported. Nevertheless, the reported anomalies have not been so far synergically analyzed to interpret or prove the potential lithosphere-coversphere-atmosphere coupling (LCAC) process. Previous studies on b value (a seismicity parameter from Gutenberg-Richter law) are also insufficient. In this work, the spatiotemporal evolution of several hydrothermal parameters related to the coversphere and atmosphere, including soil moisture, soil temperature, near-surface air temperature, and precipitable water, was comprehensively investigated. Air temperature and atmospheric aerosol were also statistically analyzed in time series with ground observations. An abnormal enhancement of aerosol occurred on 30 March 2009 and thus proved quasi-synchronous anomalies among the hydrothermal parameters from 29 to 31 March in particular places geo-related to tectonic thrusts and local topography. The three-dimensional (3-D) visualization analysis of b value revealed that regional stress accumulated to a high level, particularly in the L'Aquila basin and around regional large thrusts. Finally, the coupling effects of geospheres were discussed, and a conceptual LCAC mode was proposed to interpret the possible mechanisms of the multiple quasi-synchronous anomalies preceding the L'Aquila earthquake. Results indicate that CO2-rich fluids in deep crust might have played a significant role in the local LCAC process.

  16. The X-ray variability of Vela X-1 (3U 0900-40)

    NASA Technical Reports Server (NTRS)

    Charles, P. A.; Mason, K. O.; Culhane, J. L.; Sanford, P. W.; White, N. E.

    1976-01-01

    From observations of Vela X-1 with the MSSL 2.5-7.5 keV detector onboard Copernicus, the behavior of the source can be characterized by three phases: (1) high intensity, (2) low intensity, and (3) eclipse. Combining data from the 1972 Uhuru observations with eclipse observation yields a binary period of 8.963 + or - 0.001 days with zero phase on 1975 Feb. 6.97 + or - 0.04 UT. The low intensity phase is interpreted as being due to increased absorption in an accretion wake traveling across the line of sight (the spectral slope remains relatively constant throughout the cycle). Another period of enhanced absorption immediately after exit from eclipse may be due to a bow shock. Comparison of the two observations suggests that these structures vary from cycle to cycle and, since the orbital period is long, probably during each cycle.

  17. Continued decay in the cyclotron line energy in Hercules X-1

    NASA Astrophysics Data System (ADS)

    Staubert, R.; Klochkov, D.; Vybornov, V.; Wilms, J.; Harrison, F. A.

    2016-05-01

    The centroid energy Ecyc of the cyclotron line in the spectrum of the binary X-ray pulsar Her X-1 has been found to decrease with time on a time scale of a few tens of years - surprisingly short in astrophysical terms. This was found for the pulse phase-averaged line centroid energy using observational data from various X-ray satellites over the time period 1996 to 2012, establishing a reduction of ~4 keV. Here we report on the result of a new observation by NuSTAR performed in August 2015. The earlier results are confirmed and strengthened with respect to both the dependence of Ecyc on flux (it is still present after 2006) and the dependence on time: the long-term decay continued with the same rate, corresponding to a reduction of ~5 keV in 20 yr.

  18. Ultraviolet, X-ray, and infrared observations of HDE 226868 equals Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Treves, A.; Chiappetti, L.; Tanzi, E. G.; Tarenghi, M.; Gursky, H.; Dupree, A. K.; Hartmann, L. W.; Raymond, J.; Davis, R. J.; Black, J.

    1980-01-01

    During April, May, and July of 1978, HDE 226868, the optical counterpart of Cygnus X-1, was repeatedly observed in the ultraviolet with the IUE satellite. Some X-ray and infrared observations have been made during the same period. The general shape of the spectrum is that expected from a late O supergiant. Strong absorption features are apparent in the ultraviolet, some of which have been identified. The equivalent widths of the most prominent lines appear to be modulated with the orbital phase. This modulation is discussed in terms of the ionization contours calculated by Hatchett and McCray, for a binary X-ray source in the stellar wind of the companion.

  19. Total Electron-Impact Ionization Cross-Sections of CFx and NFx (x = 1 - 3)

    NASA Technical Reports Server (NTRS)

    Huo, Winifred M.; Tarnovsky, Vladimir; Becker, Kurt H.; Kwak, Dochan (Technical Monitor)

    2001-01-01

    The discrepancy between experimental and theoretical total electron-impact ionization cross sections for a group of fluorides, CFx, and NFx, (x = 1 - 3), is attributed to the inadequacies in previous theoretical models. Cross-sections calculated using a recently developed siBED (simulation Binary-Encounter-Dipole) model that takes into account the shielding of the long-range dipole potential between the scattering electron and target are in agreement with experimentation. The present study also carefully reanalyzed the previously reported experimental data to account for the possibility of incomplete collection of fragment ions and the presence of ion-pair formation channels. For NF3, our experimental and theoretical cross-sections compare well with the total ionization cross-sections recently reported by Haaland et al. in the region below dication formation.

  20. Using Monte-Carlo Simulations to Study the Disk Structure in Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Yao, Y.; Zhang, S. N.; Zhang, X. L.; Feng, Y. X.

    2002-01-01

    As the first dynamically determined black hole X-ray binary system, Cygnus X-1 has been studied extensively. However, its broad-band spectra in hard state with BeppoSAX is still not well understood. Besides the soft excess described by the multi-color disk model (MCD), the power- law component and a broad excess feature above 10 keV (disk reflection component), there is also an additional soft component around 1 keV, whose origin is not known currently.We propose that the additional soft component is due to the thermal Comptonization process between the s oft disk photon and the warm plasma cloud just above the disk.i.e., a warm layer. We use Monte-Carlo technique t o simulate this Compton scattering process and build several table models based on our simulation results.

  1. Correlation between X-ray flux and rotational acceleration in Vela X-1

    NASA Technical Reports Server (NTRS)

    Deeter, J. E.; Boynton, P. E.; Shibazaki, N.; Hayakawa, S.; Nagase, F.

    1989-01-01

    The results of a search for correlations between X-ray flux and angular acceleration for the accreting binary pulsar Vela X-1 are presented. Results are based on data obtained with the Hakucho satellite during the interval 1982 to 1984. In undertaking this correlation analysis, it was necessary to modify the usual statistical method to deal with conditions imposed by generally unavoidable satellite observing constraints, most notably a mismatch in sampling between the two variables. The results are suggestive of a correlation between flux and the absolute value of the angular acceleration, at a significance level of 96 percent. The implications of the methods and results for future observations and analysis are discussed.

  2. Linear polarization from tidal distortions of the Cygnus X-1 primary component

    SciTech Connect

    Bochkarev, N.G.; Karitskaia, E.A.; Loskutov, V.M.; Sokolov, V.V.

    1986-02-01

    The variability that would be introduced into the optical linear polarization of the Cyg X-1 (V1357 Cyg) binary system due to tidal deformation or shallow partial eclipses of the primary component is calculated, allowing for the optical-depth variation of the source function and single-scattering albedo in a model stellar atmosphere with Teff = 32,900 K and log g = 3.1. Angular distributions of the intensity and polarization per unit area of the stellar surface are derived for selected wavelengths, and the wavelength dependence of the corresponding polarization variability amplitude Ap is predicted. In the optical range Ap should be less than about 0.025 percent, but in principle might be detectable at short wavelengths. The observed V-band variations in p are, however an order of magnitude stronger and cannot result from tidal distortions or partial eclipses. 24 references.

  3. Strong ground motions of the 2009 L'Aquila earthquake: modeling and scenario simulations

    NASA Astrophysics Data System (ADS)

    Gallovič, F.; Ameri, G.; Pacor, F.

    2012-04-01

    On April 6, 2009 a Mw 6.3 earthquake struck the L'Aquila city, one of the largest urban centers in the Abruzzo region (Central Italy), causing a large number of casualties and damage in the town and surrounding villages. The earthquake has been recorded by several digital stations of the Italian Strong-Motion Network. The collected records represent a unique dataset in Italy in terms of number and quality of records, azimuthal coverage and presence of near-fault recordings. Soon after the earthquake the damage in the epicentral area was also assessed providing macroseismic intensity estimates, in MCS scale, for 314 localities (I ≥5). Despite the moderate magnitude of the L'Aquila earthquake, the strong-motion and macroseismic data in the vicinity of the fault depict a large variability of the observed shaking and damage. In this study we present broadband (0.1 - 10 Hz) ground motion simulations of the 2009 L'Aquila earthquake to be used for engineering purposes in the region. We utilize Hybrid Integral-Composite (HIC, Gallovič and Brokešová, 2007) approach based on a k-square kinematic rupture model, combining low-frequency coherent and high-frequency incoherent source radiation and providing omega-squared source spectral decay. We first model the recorded seismograms in order to calibrate source parameters and to assess the capabilities of the broadband simulation model. To this end, position and slip amount of the two main asperities, the largest asperity time delay and the rupture velocity distribution on the fault is constrained, based on the low-frequency slip inversion result. Synthetic Green's functions are calculated in a 1D-layered crustal model including 1D soil profiles to account for site-specific response (where available). The goodness-of-fit is evaluated in time (peak values and duration) and frequency domains (elastic and inelastic response spectra) and shows a remarkable agreement between observed and simulated data at most of the stations

  4. Geoethical implications in the L'Aquila case: scientific knowledge and communication

    NASA Astrophysics Data System (ADS)

    Di Capua, Giuseppe

    2013-04-01

    On October 22nd 2012, three and a half years after the earthquake that destroyed the city of L'Aquila (central Italy), killing more than 300 people and wounding about 1,500, a landmark judgment for the scientific research established the condemnation of six members of the Major Risks Committee of the Italian Government and a researcher of INGV (Istituto Nazionale di Geofisica e Vulcanologia), called to provide information about the evolution of the seismic sequence. The judge held that these Geoscientists were negligent during the meeting of 31st March 2009, convened to discuss the scientific aspects of the seismic risk of this area, affected by a long seismic sequence, also in the light of repeated warnings about the imminence of a strong earthquake, on the base of measurements of radon gas by an Italian independent technician, transmitted to the population by mass-media. Without going into the legal aspects of the criminal proceedings, this judgment strikes for the hardness of the condemnation to be paid by the scientists (six years of imprisonment, perpetual disqualification from public office and legal disqualification during the execution of the penalty, compensation for victims up to several hundred thousands of Euros). Some of them are scientists known worldwide for their proven skills, professionalism and experience. In conclusion, these scientists were found guilty of having contributed to the death of many people, because they have not communicated in an appropriate manner all available information on the seismic hazard and vulnerability of the area of L'Aquila. This judgment represents a watershed in the way of looking at the social role of geoscientists in the defense against natural hazards and their responsibility towards the people. But, in what does this responsibility consist of? It consists of the commitment to conduct an updated and reliable scientific research, which provides for a detailed analysis of the epistemic uncertainty for a more

  5. Did LMC X-3 Undergo a 'Her X-1-like' Anomalous Low State?

    NASA Technical Reports Server (NTRS)

    Boyd, Patricia t.

    2008-01-01

    The black hole X-ray binary LMC X-3 has been monitored by the Rossi X-ray Timing Explorer (RXTE) from its launch to the present by the All-Sky Monitor (ASM). This well-sampled light curve is supplemented by frequent pointed observations with the PCA and HEXTE instruments which provide improved sensitivity, time resolution and spectral information. The long-term X-ray luminosity of the system is strongly modulated on timescales of hundreds of days. The mean 2-10 kev X-ray flux varies by a factor of more than 100 during this long-term cycle. This variability has been attributed to the precession of a bright, tilted, and warped accretion disk---the mechanism also invoked to explain the 35-day super-orbital period in the X-ray binary pulsar system Her X-1. The ASM light curve displays a unique episode, starting in December 2003, during which LMC X-3 displayed a very low, nearly constant flux, for about 80 days. This is markedly different from the typical low-flux excursions in LMC X-3, which smoothly evolve toward and then away from a minimum flux on about a 10-day time scale. The character of the long-term variability, as measured by amplitude and characteristic time scale, is not the same after this long low state as it was before. Similar shifts in long-term period and amplitude are seen after the so-called "anomalous low states" in Her X-1, when the 35-day X-ray modulation ceases for an unpredictable length of time. These similar shifts in the long-term amplitude and timescale in the two systems suggests they share a similar mechanism which gives rise to the anomalous low states

  6. UNDERSTANDING COMPACT OBJECT FORMATION AND NATAL KICKS. III. THE CASE OF CYGNUS X-1

    SciTech Connect

    Wong, Tsing-Wai; Valsecchi, Francesca; Kalogera, Vassiliki; Fragos, Tassos E-mail: francesca@u.northwestern.edu E-mail: tfragos@cfa.harvard.edu

    2012-03-10

    In recent years, accurate observational constraints have become available for an increasing number of Galactic X-ray binaries (XRBs). Together with proper-motion measurements, we could reconstruct the full evolutionary history of XRBs back to the time of compact object formation. In this paper, we present the first study of the persistent X-ray source Cygnus X-1 that takes into account all available observational constraints. Our analysis accounts for three evolutionary phases: orbital evolution and motion through the Galactic potential after the formation of a black hole (BH), and binary orbital dynamics at the time of core collapse. We find that the mass of the BH immediate progenitor is 15.0-20.0 M{sub Sun }, and at the time of core collapse, the BH has potentially received a small kick velocity of {<=}77 km s{sup -1} at 95% confidence. If the BH progenitor mass is less than {approx}17 M{sub Sun }, a non-zero natal kick velocity is required to explain the currently observed properties of Cygnus X-1. Since the BH has only accreted mass from its companion's stellar wind, the negligible amount of accreted mass does not explain the observationally inferred BH spin of a{sub *} > 0.95, and the origin of this extreme BH spin must be connected to the BH formation itself. Right after the BH formation, we find that the BH companion is a 19.8-22.6 M{sub Sun} main-sequence star, orbiting the BH at a period of 4.7-5.2 days. Furthermore, recent observations show that the BH companion is currently super-synchronized. This super-synchronism indicates that the strength of tides exerted on the BH companion should be weaker by a factor of at least two compared to the usually adopted strength.

  7. CNO Processing in Massive Algol Binaries

    NASA Technical Reports Server (NTRS)

    Wade, Richard A.

    1998-01-01

    archive and the literature). Much of the activity under the grant was in connection with V342 Aquilae, a 3.39 day Algol system thought to be in a state of rapid mass transfer. The goal was to combine optical and ultraviolet data to arrive at a robust, informative interpretation of this unique binary system. Complete orbital phase coverage of V342 Aql was obtained spectroscopically and photometrically.

  8. CNO Processing in Massive Algol Binaries

    NASA Astrophysics Data System (ADS)

    Wade, Richard A.

    1998-08-01

    archive and the literature). Much of the activity under the grant was in connection with V342 Aquilae, a 3.39 day Algol system thought to be in a state of rapid mass transfer. The goal was to combine optical and ultraviolet data to arrive at a robust, informative interpretation of this unique binary system. Complete orbital phase coverage of V342 Aql was obtained spectroscopically and photometrically.

  9. Supershear During Nucleation of the 2009 M 6.3 L’Aquila, Italy Earthquake

    NASA Astrophysics Data System (ADS)

    Ellsworth, W. L.; Chiaraluce, L.

    2009-12-01

    The city of L’Aquila and the surrounding region of central Italy were devastated when the M 6.3 normal faulting earthquake ruptured directly beneath them on April 6, 2009. Nearfield recordings of the earthquake on 16 stations of the Italian National Strong Motion Network and MedNet station AQU show that the earthquake began with a weak nucleation phase followed 0.6 s later by a strong breakaway phase. To study the nature of the nucleation and breakaway we image the rupture process using both displacement and velocity seismograms from the nearfield accelerometers. The rupture is well-imaged by the network and during a total rupture time of about 10 s propagated 9 km up dip and 15 km to the SE, with maximum dislocations of about 1 m. To refine the image of the nucleation process, we model the first 4 s of rupture using just 4 s of broad band displacement and velocity seismograms sampled at 0.1 s on a 280 m grid. We find that the breakaway propagates up-dip at a high velocity (4.1 - 4.3 km/s) back across the area ruptured during the comparatively weak nucleation phase. Slip concentrates in the narrow rupture front, and little, if any slip follows in its wake suggesting that the breakaway was a supershear slip pulse. We are investigating the local crustal velocity structure for alternatives to supershear rupture velocity, but thus far have not found one. Previously, the breakaway phase was proposed to represent either 1) the growth of the rupture beyond the boundaries of an initial rupture in which aseismic preslip had lowered the stress, or 2) a statistical manifestation of a cascading rupture growing in an irregular manner. The L’Aquila nucleation process suggests a third possibility, that breakaway can represent initiation of a supershear slip pulse that forms through re-rupture of the initial slip area. Conditions for formation of a supershear slip pulse are restrictive. Transition to supershear rupture requires the initial stress to be relatively nearer to the

  10. The 2009 L'Aquila seismic sequence (Central Italy): fault system geometry and kinematics

    NASA Astrophysics Data System (ADS)

    Valoroso, L.; Amato, A.; Cattaneo, M.; Cecere, G.; Chiarabba, C.; Chiaraluce, L.; de Gori, P.; Delladio, A.; de Luca, G.; di Bona, M.; di Stefano, R.; Govoni, A.; Lucente, F. P.; Margheriti, L.; Mazza, S.; Monachesi, G.; Moretti, M.; Olivieri, M.; Piana Agostinetti, N.; Selvaggi, G.; Improta, L.; Piccinini, D.; Mariscal, A.; Pequegnat, C.; Schlagenhauf, A.; Salaun, G.; Traversa, P.; Voisin, C.; Zuccarello, L.; Azzaro, R.

    2009-12-01

    On April 6 (01:32 UTC) 2009 a destructive MW 6.3 earthquake struck the Abruzzi region in Central Italy, causing nearly 300 deaths, 40.000 homeless, and strong damage to the cultural heritage of the L'Aquila city and its province. Two strong earthquakes hit the area in historical times (e.g. the 1461 and 1703 events), but the main fault that drives the extension in this portion of the Apennines was unknown. The ground surveys carried out after the earthquake find ambiguous evidence of surface faulting. We use aftershocks distribution to investigate the geometry of the activated fault system and to report on spatio-temporal seismicity pattern and kinematics of the whole seismic sequence. Seismic data were recorded at both permanent stations of the Centralized Italian National Seismic Network managed by the INGV and 45 temporary stations installed in the epicentral area. To manage such a large amount of earthquakes, we implemented a semi-automatic procedure able to identify local earthquakes and to provide consistently weighted P- and S-wave arrival times. We show that this procedure yields consistent earthquake detection and high-quality arrival times data for hundreds of events per day. The accurate location for thousands of aftershocks defines a complex, 40 km long, NW-trending normal fault system, with seismicity nucleating within the upper 12 km of the crust. We show the geometry of two major SW-dipping normal faults that form a right lateral en-echelon system. The main fault activated by the 6th of April earthquake is 20 km-long, NW-trending and about 50° SW-dipping and is located below the city of L'Aquila. To the north, we find a second fault, activated on the 9th of April by a MW 5.4 earthquake, that is about 12-km-long and shows a dip angle of about 40° with hypocenters mainly located in the 6 to 10 km depth range.

  11. Coseismic ground deformations related to the 2009 L’Aquila seismic sequence (Italy)

    NASA Astrophysics Data System (ADS)

    Montone, P.; Working Group, E.

    2009-12-01

    On April 6, 2009 an earthquake of Mw=6.3 occurred in the central Apennines (Abruzzi region), rupturing a SW-dipping normal fault for a total length of about 18 km. It severely hit an area of ~2000 km2 around L’Aquila town causing 300 fatalities and thousands injured. The mainshock was followed by two major aftershocks on April 7 (Mw=5.6) and April 9 (Mw=5.4). The seismic sequence is confined in the upper 10-12 km, with the exception of April 7 earthquake with a depth of about 15 km. The focal mechanisms of the main events clearly show NW-oriented normal faulting consistent with the NE-SW trending extensional regime of the central Apennines. In this work we present the data collected during the post-earthquake field campaigns performed by the Emergeo working group (INGV prompt geological survey team). The seismic sequence produced a widespread and diversified set of geological surface effects consisting of rock falls, soil compactions and mobilization of loose deposits as well as open tectonic fractures with or without throw along pre-existing faults. Particularly, as a result of the mainshock, surface faulting occurred along the SW-dipping Paganica normal fault with a continuous extent of ~2.5 km. Ruptures consist of extensional cracks (i.e. fissures) and flexural or normal fault scarps with an orientation of N130°-N140°. Small and sporadic tectonic slip took place along the NW and SE prolongation of the Paganica fault and along its antithetic normal faults. The continuity of the Paganica ruptures, the agreement between their average trend and the focal plane solutions, the consistency with the slip distribution at depth, their location and similarity in the geometrical organization with respect to the long term evidence of the Paganica fault, lead us to interpret them as the primary surface expression of the seismogenic fault at depth. The limited extent and the small throw of the surface ruptures in comparison to the size of the Paganica compound fault scarp

  12. X-1A in flight with flight data superimposed

    NASA Technical Reports Server (NTRS)

    1953-01-01

    This photo of the X-1A includes graphs of the flight data from Maj. Charles E. Yeager's Mach 2.44 flight on December 12, 1953. (This was only a few days short of the 50th anniversary of the Wright brothers' first powered flight.) After reaching Mach 2.44, then the highest speed ever reached by a piloted aircraft, the X-1A tumbled completely out of control. The motions were so violent that Yeager cracked the plastic canopy with his helmet. He finally recovered from a inverted spin and landed on Rogers Dry Lakebed. Among the data shown are Mach number and altitude (the two top graphs). The speed and altitude changes due to the tumble are visible as jagged lines. The third graph from the bottom shows the G-forces on the airplane. During the tumble, these twice reached 8 Gs or 8 times the normal pull of gravity at sea level. (At these G forces, a 200-pound human would, in effect, weigh 1,600 pounds if a scale were placed under him in the direction of the force vector.) Producing these graphs was a slow, difficult process. The raw data from on-board instrumentation recorded on oscillograph film. Human computers then reduced the data and recorded it on data sheets, correcting for such factors as temperature and instrument errors. They used adding machines or slide rules for their calculations, pocket calculators being 20 years in the future. Three second generation Bell Aircraft Corporations X-1s were built, though four were requested. They were the X-1A (48-1384); X-1B (48-1385); X-1C (canceled and never built); X-1D (48-1386). These aircraft were similar to the X-1s, except they were five feet longer, had conventional canopies, and were powered by Reaction Motors, Inc. XLR11-RM-5 rocket engines. The RM-5, like the previous engines, had no throttle and was controlled by igniting one or more of the four thrust chambers at will. The original program outline called for the X-1A and X-1B to be used for dynamic stability and air loads investigations. The X-1D was to be used

  13. X-1E launch from B-50 mothership

    NASA Technical Reports Server (NTRS)

    1950-01-01

    Beginning in 1946, two XS-1 experimental research aircraft (later redesignated X-1s) conducted pioneering tests at Muroc Army Air Field (now Edwards Air Force Base) in California to obtain flight data on conditions in the transonic speed range. These early tests culminated on October 14, 1947, in the first piloted flight faster than Mach 1.0, the speed of sound. During November, 1947, the Air Force authorized studies that led to a contract (W-33-038-ac-20062) with Bell Aircraft to build four (later three) improved X-1 aircraft (the X-1C being cancelled). Designated X-1A (#48-1384), X-1B (#48-1385), and X-1D (#48-1386), the airplanes were ready by late 1950. The aircraft were about five feet longer and 2,500 lbs. heavier than the original X-craft planes. They used the 8-percent wing like the earlier X-craft. The D-model had a low-pressure turbo-pump and the B model was fitted with a prototype hydrogen peroxide reaction control system for later aircraft to use in exoatmospheric research flights. Access was through a lift-off canopy. The planes were finished in their bare metal color and white. The X-1D was ready first, but on what was intended to be its second flight (August 22, 1951) it was jettisoned and crashed at Muroc after an aerial explosion while still mated to its mother (B-50A [#46-006A]) ship. The long-delayed X-1 #3 airplane with the turbine pump was finally completed for the NACA in 1951. It made its first glide flight on July 20, 1951, with NACA pilot Joseph Cannon. Its second and final captive flight was on November 9, 1951. It was destroyed on the ground by an explosion and fire along with its B-50A mother ship while attempting to jettison fuel. The X-1A arrived at Muroc in January, 1953 and had its first powered flight on February 21, 1953. On December 8, 1953 with Yeager as pilot, the aircraft investigated high-speed stability and control issues. The X-1A was turned over to the NACA, but was lost to aerial explosion on August 8, 1955, shortly before

  14. Monitoring the Mass Accretion Rate in Scorpius X-1 Using the Optical Johnson B Filter

    NASA Astrophysics Data System (ADS)

    McNamara, B. J.; Norwood, J.; Harrison, T. E.; Holtzman, J.; Dukes, R.; Barker, T.

    2005-04-01

    The emission from low-mass X-ray binaries (LMXBs) arises from the accretion of mass onto a neutron star or black hole. A knowledge of the amount of mass being accreted as well as changes in this value are therefore essential inputs into models of these systems. Despite the need for this information, we currently lack an easily applied method that allows the accretion rate to be measured. X-ray color-color plots and UV observations can be used for this purpose, but these methods require access to oversubscribed satellites. Even if time is granted on these facilities, there is no guarantee that the source will be in a desired state when the observations take place. In this paper we show that an estimate of the ratio of the mass accretion rate to the Eddington rate can be obtained for Sco X-1 by using the Johnson B magnitude. Based on correlated X-ray and ground-based observations, we find that for Sco X-1, M˙/M˙E=-(0.123+/-0.007)B+2.543+/-0.085. This relation is valid when the system is on its normal and lower flaring branches. Based on theoretical models, we suggest that similar relations should also exist for other LMXBs.

  15. IBIS preliminary results on Cygnus X-1 spectral and temporal characteristics

    NASA Astrophysics Data System (ADS)

    Bazzano, A.; Bird, A. J.; Capitanio, F.; Del Santo, M.; Ubertini, P.; Zdziarski, A. A.; Di Cocco, G.; Falanga, M.; Goldoni, P.; Goldwurm, A.; Laurent, P.; Lebrun, F.; Malaguti, G.; Segreto, A.

    2003-11-01

    We report preliminary results of a broadband spectral and temporal study of the black-hole binary Cyg X-1 performed with the IBIS telescope. Cyg X-1 was the first pointed celestial target of IBIS during the INTEGRAL Performance and Verification Phase, 2002 Nov.-Dec., for a total observing time of ~ 2 Ms in both staring and dithering mode. Here, we report on only the staring, on-axis, observation performed in a stable instrument configuration. During the observing period the source was in its characteristic low/hard state, in which a few flares and dips have been detected. The IBIS/ISGRI results demonstrate that the INTEGRAL observatory offers a unique capability for studying correlations between hardness and/or flux in different bands over a wide photon energy range. One of our new results is finding that the hardness-flux correlation changes the sign twice over the 20-220 keV; first from positive to negative at ~ 50 keV, and then back to positive at ~ 120 keV. The former change appears to be due to the spectral curvature introduced by variable Compton reflection. The latter may be due spectral pivoting. Based on observations with INTEGRAL, an ESA project with instruments and science data centre funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, Spain), Czech Republic and Poland, and with the participation of Russia and the USA.

  16. Millimetre observations of a sub-arcsecond jet from Circinus X-1

    NASA Astrophysics Data System (ADS)

    Calvelo, D. E.; Fender, R. P.; Tzioumis, A. K.; Broderick, J. W.

    2012-01-01

    We present results from the first successful millimetre (combined 33 and 35 GHz) observations of the neutron star X-ray binary Circinus X-1, using the Australia Telescope Compact Array. The source was clearly detected in all three observing epochs. We see strong evidence for a periastron flare beginning at MJD 55519.9 ± 0.04 with estimated peak flux densities of up to 50 mJy and which proceeds to decline over the following 4 d. We directly resolve jet structures on sub-arcsecond scales. Flux density variability and distance from the core of nearby components suggest recent shock re-energization, though we are unable to directly connect this with the observed flare. We suggest that, if the emission is powered by an unseen outflow, then a phase delay exists between flare onset and subsequent brightening of nearby components, with flows reaching mildly relativistic velocities. Given resolved structure positions, in comparison to past observations of Cir X-1, we find evidence that jet direction may vary with distance from the core, or the source's precession parameters have changed.

  17. X-RAY PHOTOIONIZED BUBBLE IN THE WIND OF VELA X-1 PULSAR SUPERGIANT COMPANION

    SciTech Connect

    Krticka, Jiri; Skalicky, Jan; Kubat, Jiri

    2012-10-01

    Vela X-1 is the archetype of high-mass X-ray binaries (HMXBs), composed of a neutron star and a massive B supergiant. The supergiant is a source of a strong radiatively driven stellar wind. The neutron star sweeps up this wind and creates a huge amount of X-rays as a result of energy release during the process of wind accretion. Here, we provide detailed NLTE models of the Vela X-1 envelope. We study how the X-rays photoionize the wind and destroy the ions responsible for the wind acceleration. The resulting decrease of the radiative force explains the observed reduction of the wind terminal velocity in a direction to the neutron star. The X-rays create a distinct photoionized region around the neutron star filled with a stagnating flow. The existence of such photoionized bubbles is a general property of HMXBs. We unveil a new principle governing these complex objects, according to which there is an upper limit to the X-ray luminosity the compact star can have without suspending the wind due to inefficient line driving.

  18. X-Ray Photoionized Bubble in the Wind of Vela X-1 Pulsar Supergiant Companion

    NASA Astrophysics Data System (ADS)

    Krtička, Jiří; Kubát, Jiří; Skalický, Jan

    2012-10-01

    Vela X-1 is the archetype of high-mass X-ray binaries (HMXBs), composed of a neutron star and a massive B supergiant. The supergiant is a source of a strong radiatively driven stellar wind. The neutron star sweeps up this wind and creates a huge amount of X-rays as a result of energy release during the process of wind accretion. Here, we provide detailed NLTE models of the Vela X-1 envelope. We study how the X-rays photoionize the wind and destroy the ions responsible for the wind acceleration. The resulting decrease of the radiative force explains the observed reduction of the wind terminal velocity in a direction to the neutron star. The X-rays create a distinct photoionized region around the neutron star filled with a stagnating flow. The existence of such photoionized bubbles is a general property of HMXBs. We unveil a new principle governing these complex objects, according to which there is an upper limit to the X-ray luminosity the compact star can have without suspending the wind due to inefficient line driving.

  19. Multi-Satellite Observations of Cygnus X-1 to Study the Focused Wind and Absorption Dips

    NASA Technical Reports Server (NTRS)

    Hanke, Manfred; Wilms, Joern; Boeck, Moritz; Nowak, Michael A.; Schultz, Norbert S.; Pottschmidt, Katja; Lee, Julia C.

    2008-01-01

    High-mass X-ray binary systems are powered by the stellar wind of their donor stars. The X-ray state of Cygnus X-1 is correlated with the properties of the wind which defines the environment of mass accretion. Chandra-HETGS observations close to orbital phase 0 allow for an analysis of the photoionzed stellar wind at high resolution, but because of the strong variability due to soft X-ray absorption dips, simultaneous multi-satellite observations are required to track and understand the continuum, too. Besides an earlier joint Chandra and RXTE observation, we present first results from a recent campaign which represents the best broad-band spectrum of Cyg X-1 ever achieved: On 2008 April 18/19 we observed this source with XMM-Newton, Chandra, Suzaku, RXTE, INTEGRAL, Swift, and AGILE in X- and gamma-rays, as well as with VLA in the radio. After superior conjunction of the black hole, we detect soft X-ray absorption dips likely due to clumps in the focused wind covering greater than or equal to 95% of the X-ray source, with column densities likely to be of several 10(exp 23) cm(exp -2), which also affect photon energies above 20 keV via Compton scattering.

  20. The Nature and Cause of Spectral Variability in LMC X-1

    NASA Technical Reports Server (NTRS)

    Ruhlen, L.; Smith, D. M.; Scank, J. H.

    2011-01-01

    We present the results of a long-term observation campaign of the extragalactic wind-accreting black-hole X-ray binary LMC X-1, using the Proportional Counter Array on the Rossi X-Ray Timing Explorer (RXTE). The observations show that LMC X-1's accretion disk exhibits an anomalous temperature-luminosity relation. We use deep archival RXTE observations to show that large movements across the temperature-luminosity space occupied by the system can take place on time scales as short as half an hour. These changes cannot be adequately explained by perturbations that propagate from the outer disk on a viscous timescale. We propose instead that the apparent disk variations reflect rapid fluctuations within the Compton up-scattering coronal material, which occults the inner parts of the disk. The expected relationship between the observed disk luminosity and apparent disk temperature derived from the variable occultation model is quantitatively shown to be in good agreement with the observations. Two other observations support this picture: an inverse correlation between the flux in the power-law spectral component and the fitted inner disk temperature, and a near-constant total photon flux, suggesting that the inner disk is not ejected when a lower temperature is observed.

  1. Directed search for gravitational waves from Scorpius X-1 with initial LIGO data

    NASA Astrophysics Data System (ADS)

    Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Ain, A.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J. S.; Arnaud, N.; Ashton, G.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barbet, M.; Barclay, S.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Bartlett, J.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bauer, Th. S.; Baune, C.; Bavigadda, V.; Behnke, B.; Bejger, M.; Belczynski, C.; Bell, A. S.; Bell, C.; Benacquista, M.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackburn, L.; Blair, C. D.; Blair, D.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bojtos, P.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, Sukanta; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchman, S.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Diaz, J. Casanueva; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C.; Colombini, M.; Cominsky, L.; Constancio, M.; Conte, A.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, C.; Dahl, K.; Canton, T. Dal; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dartez, L.; Dattilo, V.; Dave, I.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Dominguez, E.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S.; Eberle, T.; Edo, T.; Edwards, M.; Edwards, M.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Essick, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Feldbaum, D.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fuentes-Tapia, S.; Fulda, P.; Fyffe, M.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S.; Garufi, F.; Gatto, A.; Gehrels, N.; Gemme, G.; Gendre, B.; Genin, E.; Gennai, A.; Gergely, L. Á.; Germain, V.; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gouaty, R.; Gräf, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guido, C. J.; Guo, X.; Gushwa, K.; Gustafson, E. K.; Gustafson, R.; Hacker, J.; Hall, E. D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Heidmann, A.; Heintze, M.; Heinzel, G.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E.; Howell, E. J.; Hu, Y. M.; Huerta, E.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Idrisy, A.; Indik, N.; Ingram, D. R.; Inta, R.; Islas, G.; Isler, J. C.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacobson, M.; Jang, H.; Jaranowski, P.; Jawahar, S.; Ji, Y.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, K.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Kéfélian, F.; Keiser, G. M.; Keitel, D.; Kelley, D. B.; Kells, W.; Keppel, D. G.; Key, J. S.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, C.; Kim, K.; Kim, N. G.; Kim, N.; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Koehlenbeck, S.; Kokeyama, K.; Kondrashov, V.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Kringel, V.; Krishnan, B.; Królak, A.; Krueger, C.; Kuehn, G.; Kumar, A.; Kumar, P.; Kuo, L.; Kutynia, A.; Landry, M.; Lantz, B.; Larson, S.; Lasky, P. D.; Lazzarini, A.; Lazzaro, C.; Lazzaro, C.; Le, J.; Leaci, P.; Leavey, S.; Lebigot, E.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Levine, B.; Lewis, J.; Li, T. G. F.; Libbrecht, K.; Libson, A.; Lin, A. C.; Littenberg, T. B.; Lockerbie, N. A.; Lockett, V.; Logue, J.; Lombardi, A. L.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Lubinski, M. J.; Lück, H.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macarthur, J.; MacDonald, T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña-Sandoval, F.; Magee, R.; Mageswaran, M.; Maglione, C.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandel, I.; Mandic, V.; Mangano, V.; Mangano, V.; Mansell, G. L.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McLin, K.; McWilliams, S.; Meacher, D.; Meadors, G. D.; Meidam, J.; Meinders, M.; Melatos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Moggi, A.; Mohan, M.; Mohanty, S. D.; Mohapatra, S. R. P.; Moore, B.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nagy, M. F.; Nardecchia, I.; Nash, T.; Naticchioni, L.; Nayak, R. K.; Necula, V.; Nedkova, K.; Nelemans, G.; Neri, I.; Neri, M.; Newton, G.; Nguyen, T.; Nielsen, A. B.; Nissanke, S.; Nitz, A. H.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oppermann, P.; Oram, R.; O'Reilly, B.; Ortega, W.; O'Shaughnessy, R.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Padilla, C.; Pai, A.; Pai, S.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Papa, M. A.; Paris, H.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patrick, Z.; Pedraza, M.; Pekowsky, L.; Pele, A.; Penn, S.; Perreca, A.; Phelps, M.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poeld, J.; Poggiani, R.; Post, A.; Poteomkin, A.; Powell, J.; Prasad, J.; Predoi, V.; Premachandra, S.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qin, J.; Quetschke, V.; Quintero, E.; Quiroga, G.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Raja, S.; Rajalakshmi, G.; Rakhmanov, M.; Ramirez, K.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Reed, C. M.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Reula, O.; Ricci, F.; Riles, K.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Saleem, M.; Salemi, F.; Sammut, L.; Sandberg, V.; Sanders, J. R.; Sannibale, V.; Santiago-Prieto, I.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R.; Sawadsky, A.; Scheuer, J.; Schilling, R.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Serna, G.; Sevigny, A.; Shaddock, D. A.; Shah, S.; Shahriar, M. S.; Shaltev, M.; Shao, Z.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siellez, K.; Siemens, X.; Sigg, D.; Silva, A. D.; Simakov, D.; Singer, A.; Singer, L.; Singh, R.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Son, E. J.; Sorazu, B.; Souradeep, T.; Staley, A.; Stebbins, J.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Steplewski, S.; Stevenson, S.; Stone, R.; Strain, K. A.; Straniero, N.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sutton, P. J.; Swinkels, B.; Szczepanczyk, M.; Szeifert, G.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, R.; Tellez, G.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, V.; Tomlinson, C.; Tonelli, M.; Torres, C. V.; Torrie, C. I.; Travasso, F.; Traylor, G.; Tse, M.; Tshilumba, D.; Turconi, M.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Vajente, G.; Valdes, G.; Vallisneri, M.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; van den Broeck, C.; van der Sluys, M. V.; van Heijningen, J.; van Veggel, A. A.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Vetrano, F.; Viceré, A.; Vincent-Finley, R.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, H.; Wang, M.; Wang, X.; Ward, R. L.; Warner, J.; Was, M.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; White, D. J.; Whiting, B. F.; Wilkinson, C.; Williams, L.; Williams, R.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Xie, S.; Yablon, J.; Yakushin, I.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yang, Q.; Yvert, M.; ZadroŻny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, Fan; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhu, X. J.; Zucker, M. E.; Zuraw, S.; Zweizig, J.; LIGO Scientific Collaboration, Virgo Collaboration

    2015-03-01

    We present results of a search for continuously emitted gravitational radiation, directed at the brightest low-mass x-ray binary, Scorpius X-1. Our semicoherent analysis covers 10 days of LIGO S5 data ranging from 50-550 Hz, and performs an incoherent sum of coherent F -statistic power distributed amongst frequency-modulated orbital sidebands. All candidates not removed at the veto stage were found to be consistent with noise at a 1% false alarm rate. We present Bayesian 95% confidence upper limits on gravitational-wave strain amplitude using two different prior distributions: a standard one, with no a priori assumptions about the orientation of Scorpius X-1; and an angle-restricted one, using a prior derived from electromagnetic observations. Median strain upper limits of 1.3 ×10-24 and 8 ×10-25 are reported at 150 Hz for the standard and angle-restricted searches respectively. This proof-of-principle analysis was limited to a short observation time by unknown effects of accretion on the intrinsic spin frequency of the neutron star, but improves upon previous upper limits by factors of ˜1.4 for the standard, and 2.3 for the angle-restricted search at the sensitive region of the detector.

  2. A DETERMINATION OF THE SPIN OF THE BLACK HOLE PRIMARY IN LMC X-1

    SciTech Connect

    Gou Lijun; McClintock, Jeffrey E.; Liu Jifeng; Narayan, Ramesh; Steiner, James F.; Remillard, Ronald A.; Orosz, Jerome A.; Davis, Shane W.; Ebisawa, Ken

    2009-08-20

    The first extragalactic X-ray binary, LMC X-1, was discovered in 1969. In the 1980s, its compact primary was established as the fourth dynamical black hole candidate. Recently, we published accurate values for the mass of the black hole and the orbital inclination angle of the binary system. Building on these results, we have analyzed 53 X-ray spectra obtained by RXTE and, using a selected sample of 18 of these spectra, we have determined the dimensionless spin parameter of the black hole to be a{sub *} = 0.92{sup +0.05}{sub -0.07}. This result takes into account all sources of observational and model-parameter uncertainties. The standard deviation around the mean value of a{sub *} for these 18 X-ray spectra, which were obtained over a span of several years, is only {delta}a{sub *} = 0.02. When we consider our complete sample of 53 RXTE spectra, we find a somewhat higher value of the spin parameter and a larger standard deviation. Finally, we show that our results based on RXTE data are confirmed by our analyses of selected X-ray spectra obtained by the XMM-Newton, BeppoSAX, and Ginga missions.

  3. On the possible existence of brightness spots on the Cyg X-1 supergiant

    NASA Astrophysics Data System (ADS)

    Karitskaya, E. A.; Bochkarev, N. G.

    2014-11-01

    A magnetic field was recently detected on the O9.7 Iab supergiant component of the Cyg X-1 X-ray binary system. This paper considers its impact upon the star's atmosphere. We have used the simple model of a unipolar cylindrically symmetric circumpolar magnetic spot in static approximation with the parallel magnetic force lines. In that model the Lorentz-force component related to the force line curvature can be neglected and the equation of hydrostatic equilibrium is nabla (P_{g}+P_{r}+{B^2}/{8π}) = ρ{g} , where P_{g} and P_{r} are the gaseous and radiative pressures, respectively, B^2/8π is the isotropic magnetic pressure, g is the gravitation acceleration, and ρ is the gas density. In the frame of this model, and of the model atmosphere that we calculated for the Cyg X-1 O-supergiant te{skb}, the magnetic pressure was found to be comparable with the model atmosphere gas and radiative pressures, and exceeded them in the area surrounding the magnetic poles. That condition should lead to the formation of circumpolar bright spots on the stellar surface. We estimate their brightness contrast to be 25 A dipolar or quadrupolar magnetic field can create large bright spots, which can be studied by ground-based optical photometry. If the magnetic field is inclined to the stellar rotation axis, the anticipated variability may reach about 1% can form spots of lesser size, and those may be revealed only by space telescopes. The spots may also be revealed through variability in spectral line profiles. The observation of spots can be considered an independent instrument for the analysis of magnetic fields in O-type supergiants such as that in Cyg X-1. The full text of this contribution has been published in te{kb}.

  4. Correlated optical observations with BATSE/CGRO on SCO X-1

    NASA Technical Reports Server (NTRS)

    Mcnamara, Bernard

    1992-01-01

    The Burst and Transient Source Experiment (BATSE) instrument on the Compton Gamma-Ray Observatory consists of two banks of eight instruments referred to as the Large Area Detectors (LADs) and the Spectroscopic Detectors (SDs). Each LAD crystal is 50.8 cm in diameter by 1.27 cm thick while for a SD these values are 12.7 cm in diameter by 7.62 cm in diameter. Both the LADs and SDs are NaI(TI) scintillation detectors. The LADs and SDs are situated on the CGRO spacecraft so as to provide all sky coverage for both sets of detectors. The SDs have the ability to measure energies in the 8-16 keV range whereas the minimum energy at which the LADs operate is near 20 keV. SCO X-1 is the brightest continuous x-ray source in the sky. It is believed to consist of a low mass star orbiting and transferring mass onto a neutron star. It is representative of a class of similar objects referred to as low mass x-ray binaries (LMXB). Because SCO X-1 serves as the prototype of this class of x-ray emitters and since its detectable emission is so large, it warrants extended study. One of the most fruitful techniques of studying a LMXB system is by simultaneously monitoring its emission at a variety of different wavelengths. These correlated datasets can be used to probe the source environment, investigate emission mechanisms, and examine the mass transfer process itself. In principle, the BATSE SDs have the capability of providing a nearly continuous 8-16 keV record of SCO X-1 activity. The aim of this study was to investigate the feasibility of using the BATSE SDs along with simultaneous optical measurements to study this source.

  5. NuSTAR discovery of a luminosity dependent cyclotron line energy in Vela X-1

    SciTech Connect

    Fürst, Felix; Grefenstette, Brian W.; Harrison, Fiona; Madsen, Kristin K.; Walton, Dominic J.; Pottschmidt, Katja; Wilms, Jörn; Tomsick, John A.; Boggs, Steven E.; Craig, William W.; Bachetti, Matteo; Christensen, Finn E.; Hailey, Charles J.; Miller, Jon M.; Stern, Daniel; Zhang, William

    2014-01-10

    We present NuSTAR observations of Vela X-1, a persistent, yet highly variable, neutron star high-mass X-ray binary (HMXB). Two observations were taken at similar orbital phases but separated by nearly a year. They show very different 3-79 keV flux levels as well as strong variability during each observation, covering almost one order of magnitude in flux. These observations allow, for the first time ever, investigations on kilo-second time-scales of how the centroid energies of cyclotron resonant scattering features (CRSFs) depend on flux for a persistent HMXB. We find that the line energy of the harmonic CRSF is correlated with flux, as expected in the sub-critical accretion regime. We argue that Vela X-1 has a very narrow accretion column with a radius of around 0.4 km that sustains a Coulomb interaction dominated shock at the observed luminosities of L {sub x} ∼ 3 × 10{sup 36} erg s{sup –1}. Besides the prominent harmonic line at 55 keV the fundamental line around 25 keV is clearly detected. We find that the strengths of the two CRSFs are anti-correlated, which we explain by photon spawning. This anti-correlation is a possible explanation for the debate about the existence of the fundamental line. The ratio of the line energies is variable with time and deviates significantly from 2.0, also a possible consequence of photon spawning, which changes the shape of the line. During the second observation, Vela X-1 showed a short off-state in which the power-law softened and a cut-off was no longer measurable. It is likely that the source switched to a different accretion regime at these low mass accretion rates, explaining the drastic change in spectral shape.

  6. What is special about Cygnus X-1 - Black holes in theory and observation: X-ray observations

    NASA Technical Reports Server (NTRS)

    Boldt, E.; Holt, S.; Rothschild, R.; Serlemitsos, P.

    1975-01-01

    Of the eight X-ray sources now known which may be associated with binary stellar systems, Cygnus X-1 is the most likely candidate for being a black hole. The X-ray evidence from several experiments is reviewed, with special emphasis on those characteristics which appear to distinguish Cygnus X-1 from other compact X-ray emitting objects. Data are examined within the context of a model in which millisecond bursts (Rothschild et al., 1974) are superposed on shot-noise fluctuations (Terrell, 1972) arising from 'events' of durations on the order of a second. Possible spectral-temporal correlations are investigated which indicate new measurements that need to be made in future experiments.

  7. Longterm lightcurves of X-ray binaries

    NASA Astrophysics Data System (ADS)

    Clarkson, William

    The X-ray Binaries (XRB) consist of a compact object and a stellar companion, which undergoes large-scale mass-loss to the compact object by virtue of the tight ( P orb usually hours-days) orbit, producing an accretion disk surrounding the compact object. The liberation of gravitational potential energy powers exotic high-energy phenomena, indeed the resulting accretion/ outflow process is among the most efficient energy-conversion machines in the universe. The Burst And Transient Source Experiment (BATSE) and RXTE All Sky Monitor (ASM) have provided remarkable X-ray lightcurves above 1.3keV for the entire sky, at near-continuous coverage, for intervals of 9 and 7 years respectively (with ~3 years' overlap). With an order of magnitude increase in sensitivity compared to previous survey instruments, these instruments have provided new insight into the high-energy behaviour of XRBs on timescales of tens to thousands of binary orbits. This thesis describes detailed examination of the long-term X-ray lightcurves of the neutron star XRB X2127+119, SMC X-1, Her X- 1, LMC X-4, Cyg X-2 and the as yet unclassified Circinus X-1, and for Cir X-1, complementary observations in the IR band. Chapters 1 & 2 introduce X-ray Binaries in general and longterm periodicities in particular. Chapter 3 introduces the longterm datasets around which this work is based, and the chosen methods of analysis of these datasets. Chapter 4 examines the burst history of the XRB X2127+119, suggesting three possible interpretations of the apparently contradictory X-ray emission from this system, including a possible confusion of two spatially distinct sources (which was later vindicated by high-resolution imaging). Chapters 5 and 6 describe the characterisation of accretion disk warping, providing observational verification of the prevailing theoretical framework for such disk-warps. Chapters 7 & 8 examine the enigmatic XRB Circinus X-1 with high-resolution IR spectroscopy (chapter 7) and the RXTE

  8. Precursory slow-slip loaded the 2009 L'Aquila earthquake sequence

    NASA Astrophysics Data System (ADS)

    Borghi, A.; Aoudia, A.; Javed, F.; Barzaghi, R.

    2016-05-01

    Slow-slip events (SSEs) are common at subduction zone faults where large mega earthquakes occur. We report here that one of the best-recorded moderate size continental earthquake, the 2009 April 6 moment magnitude (Mw) 6.3 L'Aquila (Italy) earthquake, was preceded by a 5.9 Mw SSE that originated from the decollement beneath the reactivated normal faulting system. The SSE is identified from a rigorous analysis of continuous GPS stations and occurred on the 12 February and lasted for almost two weeks. It coincided with a burst in the foreshock activity with small repeating earthquakes migrating towards the main-shock hypocentre as well as with a change in the elastic properties of rocks in the fault region. The SSE has caused substantial stress loading at seismogenic depths where the magnitude 4.0 foreshock and Mw 6.3 main shock nucleated. This stress loading is also spatially correlated with the lateral extent of the aftershock sequence.

  9. Rubble masonry response under cyclic actions: The experience of L'Aquila city (Italy)

    NASA Astrophysics Data System (ADS)

    Fonti, Roberta; Barthel, Rainer; Formisano, Antonio; Borri, Antonio; Candela, Michele

    2015-12-01

    Several methods of analysis are available in engineering practice to study old masonry constructions. Two commonly used approaches in the field of seismic engineering are global and local analyses. Despite several years of research in this field, the various methodologies suffer from a lack of comprehensive experimental validation. This is mainly due to the difficulty in simulating the many different kinds of masonry and, accordingly, the non-linear response under horizontal actions. This issue can be addressed by examining the local response of isolated panels under monotonic and/or alternate actions. Different testing methodologies are commonly used to identify the local response of old masonry. These range from simplified pull-out tests to sophisticated in-plane monotonic tests. However, there is a lack of both knowledge and critical comparison between experimental validations and numerical simulations. This is mainly due to the difficulties in implementing irregular settings within both simplified and advanced numerical analyses. Similarly, the simulation of degradation effects within laboratory tests is difficult with respect to old masonry in-situ boundary conditions. Numerical models, particularly on rubble masonry, are commonly simplified. They are mainly based on a kinematic chain of rigid blocks able to perform different "modes of damage" of structures subjected to horizontal actions. This paper presents an innovative methodology for testing; its aim is to identify a simplified model for out-of-plane response of rubbleworks with respect to the experimental evidence. The case study of L'Aquila district is discussed.

  10. Rubble masonry response under cyclic actions: The experience of L’Aquila city (Italy)

    SciTech Connect

    Fonti, Roberta Barthel, Rainer; Formisano, Antonio; Borri, Antonio; Candela, Michele

    2015-12-31

    Several methods of analysis are available in engineering practice to study old masonry constructions. Two commonly used approaches in the field of seismic engineering are global and local analyses. Despite several years of research in this field, the various methodologies suffer from a lack of comprehensive experimental validation. This is mainly due to the difficulty in simulating the many different kinds of masonry and, accordingly, the non-linear response under horizontal actions. This issue can be addressed by examining the local response of isolated panels under monotonic and/or alternate actions. Different testing methodologies are commonly used to identify the local response of old masonry. These range from simplified pull-out tests to sophisticated in-plane monotonic tests. However, there is a lack of both knowledge and critical comparison between experimental validations and numerical simulations. This is mainly due to the difficulties in implementing irregular settings within both simplified and advanced numerical analyses. Similarly, the simulation of degradation effects within laboratory tests is difficult with respect to old masonry in-situ boundary conditions. Numerical models, particularly on rubble masonry, are commonly simplified. They are mainly based on a kinematic chain of rigid blocks able to perform different “modes of damage” of structures subjected to horizontal actions. This paper presents an innovative methodology for testing; its aim is to identify a simplified model for out-of-plane response of rubbleworks with respect to the experimental evidence. The case study of L’Aquila district is discussed.

  11. Assessment of lead exposure in Spanish imperial eagle (Aquila adalberti) from spent ammunition in central Spain

    USGS Publications Warehouse

    Fernandez, Julia Rodriguez-Ramos; Hofle, Ursula; Mateo, Rafael; de Francisco, Olga Nicolas; Abbott, Rachel; Acevedo, Pelayo; Blanco, Juan-Manuel

    2011-01-01

    The Spanish imperial eagle (Aquila adalberti) is found only in the Iberian Peninsula and is considered one of the most threatened birds of prey in Europe. Here we analyze lead concentrations in bones (n = 84), livers (n = 15), primary feathers (n = 69), secondary feathers (n = 71) and blood feathers (n = 14) of 85 individuals collected between 1997 and 2008 in central Spain. Three birds (3.6%) had bone lead concentration > 20 (mu or u)g/g and all livers were within background lead concentration. Bone lead concentrations increased with the age of the birds and were correlated with lead concentration in rachis of secondary feathers. Spatial aggregation of elevated bone lead concentration was found in some areas of Montes de Toledo. Lead concentrations in feathers were positively associated with the density of large game animals in the area where birds were found dead or injured. Discontinuous lead exposure in eagles was evidenced by differences in lead concentration in longitudinal portions of the rachis of feathers.

  12. The Genome Sequence of a Widespread Apex Predator, the Golden Eagle (Aquila chrysaetos)

    PubMed Central

    Doyle, Jacqueline M.; Katzner, Todd E.; Bloom, Peter H.; Ji, Yanzhu; Wijayawardena, Bhagya K.; DeWoody, J. Andrew

    2014-01-01

    Biologists routinely use molecular markers to identify conservation units, to quantify genetic connectivity, to estimate population sizes, and to identify targets of selection. Many imperiled eagle populations require such efforts and would benefit from enhanced genomic resources. We sequenced, assembled, and annotated the first eagle genome using DNA from a male golden eagle (Aquila chrysaetos) captured in western North America. We constructed genomic libraries that were sequenced using Illumina technology and assembled the high-quality data to a depth of ∼40x coverage. The genome assembly includes 2,552 scaffolds >10 Kb and 415 scaffolds >1.2 Mb. We annotated 16,571 genes that are involved in myriad biological processes, including such disparate traits as beak formation and color vision. We also identified repetitive regions spanning 92 Mb (∼6% of the assembly), including LINES, SINES, LTR-RTs and DNA transposons. The mitochondrial genome encompasses 17,332 bp and is ∼91% identical to the Mountain Hawk-Eagle (Nisaetus nipalensis). Finally, the data reveal that several anonymous microsatellites commonly used for population studies are embedded within protein-coding genes and thus may not have evolved in a neutral fashion. Because the genome sequence includes ∼800,000 novel polymorphisms, markers can now be chosen based on their proximity to functional genes involved in migration, carnivory, and other biological processes. PMID:24759626

  13. Relationship between demographics and diet specificity of Imperial Eagles Aquila heliaca in Kazakhstan

    USGS Publications Warehouse

    Katzner, Todd; Bragin, E.; Knick, Steven T.; Smith, Andrew T.

    2005-01-01

    The demographic consequences of within-population variability in predator foraging are not well understood. We assessed the relationship between the degree of diet specialization and two demographic parameters, population density and reproductive output, within a single population of Imperial Eagles Aquila heliaca at a nature reserve in north-central Kazakhstan. Nearest-neighbour distances between eagle nests throughout the reserve, and thus population density, were correlated with the degree to which diets were specialized. Diet diversity showed an extensive regional variability that was linked to prey distributions, but within-year analyses of reproductive output did not show similar linkages. However, multi-year analyses of breeding performance showed inter-regional differences in nesting success that were paralleled, and probably driven by, similar trends in diet diversity. In contrast, brood size at fledging was not linked to diet diversity and was more probably driven by reserve-wide influences such as weather. Finally, the decision to initiate breeding was associated neither with diet diversity nor with environmental variability. Our results indicate that the degree of dietary specialization is linked to the demographics of Imperial Eagle populations. For these and other raptor populations, it is possible that management could be used separately to increase or decrease nesting success, brood size at fledging, and the likelihood that a pair will initiate breeding.

  14. Mange Caused by a Novel Micnemidocoptes Mite in a Golden Eagle ( Aquila chrysaetos ).

    PubMed

    Sadar, Miranda J; Sanchez-Migallon Guzman, David; Mete, Asli; Foley, Janet; Stephenson, Nicole; Rogers, Krysta H; Grosset, Claire; Smallwood, K Shawn; Shipman, Jessica; Wells, Amy; White, Stephen D; Bell, Douglas A; Hawkins, Michelle G

    2015-09-01

    A second-year, female golden eagle ( Aquila chrysaetos ) was live trapped in northern California because of severe feather loss and crusting of the skin on the head and legs. On physical examination, the bird was lethargic, dehydrated, and thin, with severe feather loss and diffuse hyperemia and crusting on the head, ventral wings, ventrum, dorsum, and pelvic limbs. Mites morphologically similar to Micnemidocoptes derooi were identified with scanning electron microscopy. The eagle was treated with ivermectin (0.4 mg/kg) once weekly for 7 weeks, as well as pyrethrin, meloxicam, ceftiofur crystalline free acid, and voriconazole. Although the eagle's condition improved, and live mites or eggs were not evident on skin scrapings at the time of completion of ivermectin treatment, evidence of dead mites and mite feces were present after the last dose of ivermectin. Two additional doses of ivermectin and 2 doses of topical selamectin (23 mg/kg) were administered 2 and 4 weeks apart, respectively. No mite eggs, feces, or adults were evident after treatment was completed. A second golden eagle found in the same region was also affected with this mite but died soon after presentation. This is the first report, to our knowledge, of successful treatment, as well as treatment with selamectin, of mites consistent with Micnemidocoptes species in any raptorial species. PMID:26378670

  15. CHARACTERIZATION OF NATURAL EJACULATES AND SPERM CRYOPRESERVATION IN A GOLDEN EAGLE (AQUILA CHRYSAETUS).

    PubMed

    Villaverde-Morcillo, Silvia; García-Sánchez, Rubén; Castaño, Cristina; Rodríguez, Eduar; Gonzalez, Fernando; Esteso, Milagros; Santiago-Moreno, Julián

    2015-06-01

    This paper describes the sperm characteristics and response to cooling and freezing of naturally ejaculated semen from a captive, adult golden eagle (Aquila chrysaetus) trained to allow sperm recovery via cooperative copulation. A basic spermiogram was prepared, and sperm motility and morphometric variables recorded using a computer-aided system. For sperm storage, the effects of a polyvinylpyrrolidone-based extender were evaluated at 5°C. The same extender was also used in freezing procedures in which glycerol (11%) and dimethylacetamide (6%) were compared as cryoprotectants. The extender preserved sperm viability over storage periods of up to 6 days. Although sperm motility and percentage live sperm values were poorer for frozen-thawed (5.8-14.6% and 44-42%, respectively) than for fresh samples (46.7 and 74.6%, respectively), no differences were seen between the effects of the two cryoprotectants. These results could be of use when attempting to store the sperm of golden eagles and other raptors. PMID:26056889

  16. Headache prevalence in the population of L'Aquila (Italy) after the 2009 earthquake.

    PubMed

    Guetti, Cristiana; Angeletti, Chiara; Papola, Roberta; Petrucci, Emiliano; Ursini, Maria Laura; Ciccozzi, Alessandra; Marinangeli, Franco; Paladini, Antonella; Varrassi, Giustino

    2011-04-01

    Stress induced by the events of daily life is considered a major factor in pathogenesis of primary tension-type headache. Little is known about the impact that could have a more stressful event, like a natural disaster, both in patients with chronic headache, both in people that do not had headache previously. The aim of the present study was to observe the prevalence of headache in the population following the devastating earthquake that affected the province of L'Aquila on April 6, 2009. The study population was conducted in four tent cities (Onna, Bazzano, Tempera-St. Biagio, Paganica). Sanitary access is recorded in the registers of medical triage, in the first 5 weeks, after the April 6, 2009. The prevalence of primary headache presentation was 5.53% (95% CI 4.2-7.1), secondary headache was 2.82% (95% CI 1.9-4.9). Pain intensity, assessed by Numerical Rating Scale score showed a mean value of 7±1.1 (range 4-10). The drugs most used were the NSAIDs (46%) and paracetamol (36%), for impossibility of finding causal drugs. This study shows how more stressful events not only have an important role in determining acute exacerbation of chronic headache, but probably also play a pathogenic role in the emergence of primary headache. Also underlines the lack of diagnostic guidelines or operating protocols to early identify and treat headache in the emergency settings. PMID:21331753

  17. RXTE Observation of Cygnus X-1: Spectra and Timing

    NASA Technical Reports Server (NTRS)

    Wilms, J.; Dove, J.; Nowak, M.; Vaughan, B. A.

    1997-01-01

    We present preliminary results from the analysis of an R.XTE observation of Cyg X-1 in the hard state. We show that the observed X-ray spectrum can be explained with a model for an accretion disk corona (ADC), in which a hot sphere is situated inside of a cold accretion disk (similar to an advection dominated model). ADC Models with a slab-geometry do not successfully fit the data. In addition to the spectral results we present the observed temporal properties of Cyg X-1, i.e. the coherence-function and the time-lags, and discuss the constraints the. temporal properties imply for the accretion geometry in Cyg X-1.

  18. XMM-Newton observations of CYGNUS X-1

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard F. (Technical Monitor); Miller, Jon

    2005-01-01

    Observations of Cygnus X-1 were first attempted under this program in the spring of 2004, but were complicated by instrumental flaring problems. Successful observations were completed in the fall of 2004, and processed data were delivered to the PI in the winter and spring of 2005. Thus, focused work on this data was only possible starting in 2005. A preliminary reduction and analysis of data from the EPIC CCD cameras and the Reflection Grating Spectrometer has been made. The EPIC spectra reveal the best example of a broadened, relativistic iron emission line yet found in Cygnus X-1. The Oxygen K-shell region has been shown to be a very complex wavelength range in numerous spectra of accreting sources, but the RGS spectra reveal this region in great detail and will be important in understanding the wind from the 0-type donor star that is focused onto the black hole in Cygnus X-1.

  19. Coordinated Xmm-Newton Spectroscopy of Circinus X-1

    NASA Astrophysics Data System (ADS)

    Shirey, Robert

    During absorption dips in the unusual LMXB Circinus X-1, a bright spectral component is obscured, revealing a faint scattered component. Using RXTE, we found a similar Fe Kalpha flux inside and outside dips, suggesting that Fe fluorescence occurs in the scattering medium. Our extensive RXTE study also revealed that intensity flares in Cir X-1 are associated with branches of a Z-source track. We discovered an unusual line- or edge-like feature near 10 keV on the normal and flaring branches. We propose observations with RXTE during our approved XMM- Newton AO-1 observations of Cir X-1 in order to perform simultaneous broad-band and high-resolution spectroscopy during dips and flares.

  20. Precision ephemerides for gravitational-wave searches. I. Sco X-1

    SciTech Connect

    Galloway, Duncan K.; Premachandra, Sammanani; Steeghs, Danny; Marsh, Tom; Casares, Jorge; Cornelisse, Rémon

    2014-01-20

    Rapidly rotating neutron stars are the only candidates for persistent high-frequency gravitational wave emission, for which a targeted search can be performed based on the spin period measured from electromagnetic (e.g., radio and X-ray) observations. The principal factor determining the sensitivity of such searches is the measurement precision of the physical parameters of the system. Neutron stars in X-ray binaries present additional computational demands for searches due to the uncertainty in the binary parameters. We present the results of a pilot study with the goal of improving the measurement precision of binary orbital parameters for candidate gravitational wave sources. We observed the optical counterpart of Sco X-1 in 2011 June with the William Herschel Telescope and also made use of Very Large Telescope observations in 2011 to provide an additional epoch of radial-velocity measurements to earlier measurements in 1999. From a circular orbit fit to the combined data set, we obtained an improvement of a factor of 2 in the orbital period precision and a factor of 2.5 in the epoch of inferior conjunction T {sub 0}. While the new orbital period is consistent with the previous value of Gottlieb et al., the new T {sub 0} (and the amplitude of variation of the Bowen line velocities) exhibited a significant shift, which we attribute to variations in the emission geometry with epoch. We propagate the uncertainties on these parameters through to the expected Advanced LIGO-Virgo detector network observation epochs and quantify the improvement obtained with additional optical observations.

  1. Determination of the atmospheric structure of the BO star companion of SMC X-1 by analysis of Ginga observations

    NASA Technical Reports Server (NTRS)

    Clark, George W.

    1994-01-01

    The x-ray phenomena of the binary system SMC X-1/Sk 160, observed with the Ginga and ROSAT x-ray observatories, are compared with computed phenomena derived from a three dimensional hydrodynamical model of the stellar wind perturbed by x-ray heating and ionization which is described in the accompanying paper. In the model the BOI primary star has a line-driven stellar wind in the region of the x-ray shadow and a thermal wind in the region heated by x-rays. We find general agreement between the observed and predicted x-ray spectra throughout the binary orbit cycle, including the extended, variable, and asymmetric eclipse transitions and the period of deep eclipse.

  2. Search for Binary Trojans

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.; Grundy, W. M.; Ryan, E. L.; Benecchi, S. D.

    2015-11-01

    We have reexamined 41 Trojan asteroids observed with the Hubble Space Telescope (HST) to search for unresolved binaries. We have identified one candidate binary with a separation of 53 milliarcsec, about the width of the diffraction limited point-spread function (PSF). Sub-resolution-element detection of binaries is possible with HST because of the high signal-to-noise ratio of the observations and the stability of the PSF. Identification and confirmation of binary Trojans is important because a Trojan Tour is one of five possible New Frontiers missions. A binary could constitute a potentially high value target because of the opportunity to study two objects and to test models of the primordial nature of binaries. The potential to derive mass-based physical information from the binary orbit could yield more clues to the origin of Trojans.

  3. [Health status and access to health services by the population of L'Aquila (Abruzzo Region, Italy) six years after the earthquake].

    PubMed

    Altobelli, Emma; Vittorini, Pierpaolo; Leuter, Cinzia; Bianchini, Valeria; Angelone, Anna Maria; Aloisio, Federica; Cofini, Vincenza; Zazzara, Francesca; Di Orio, Ferdinando

    2016-01-01

    Natural disasters, such as the earthquake that occurred in the province of L'Aquila in central Italy, in 2009, generally increase the demand for healthcare. A survey was conducted to assess perception of health status an d use of health services in a sample of L'Aquila's resident population, five years after the event, and in a comparison population consisting of a sample of the resident population of Avezzano, a town in the same region, not affected by the earthquake. No differences were found in perception of health status between the two populations. Both groups reported difficulties in accessing specialized healthcare and rehabilitation services. PMID:27077558

  4. Response of the middle atmosphere to Sco X-1

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Barcus, J. R.; Mitchell, J. D.

    1985-01-01

    On the night of Mar. 9, 1983 (UT) at Punta Lobos Launch Site, Peru (12.5 deg S, 76.8 deg W, magnetic dip -0.7 deg), a sequence of sounding rockets was flown to study the electrical structure of the equatorial middle atmosphere and to evaluate perturbations on this environment induced by the X-ray star Sco X-1. The rocket series was anchored by two Nike Orion payloads (31.032 and 31.033) which were launched at 0327 and 0857 UT, near Sco X-1 star-rise and after it had attained an elevation angle of 70 deg E. An enhanced flux of X-rays was observed on the second Nike Orion flight (31.033). This increase is directly attributed to Sco X-1, both from the spectral properties of the measured X-ray distribution and by spatial information acquired from a spinning X-ray detector during the upleg portion of the 31.033 flight. Simultaneously, a growth in ion conductivity and density was seen to occur in the lower mesosphere between 60 and 80 km on the second flight, specifically in the region of maximum energy deposition by the Sco X-1 X-rays. The results imply the presence of a significant number of ionized heavy constituents within the lower mesosphere, with masses possibly in the submacroscopoic range.

  5. Sunspot 1520 Releases Strong (X1.4) Solar Flare

    NASA Video Gallery

    This movie shows the sun July 10-12, ending with the X1.4 class flare on July 12, 2012. It was captured by NASA’s Solar Dynamics Observatory in the 131 Angstrom wavelength - a wavelength that is...

  6. Preconceptual design requirements for the X-1 Advanced Radiation Source

    SciTech Connect

    Rochau, G.E.; Hands, J.A.; Raglin, P.S.; Ramirez, J.J.; Goldstein, S.A.; Cereghino, S.J.; MacLeod, G.

    1998-09-01

    The X-1 Advanced Radiation Source represents the next step in providing the US Department of Energy`s Stockpile Stewardship Program with the high-energy, large volume, laboratory x-ray source for the Radiation Effects Science and Simulation, Inertial Confinement Fusion, and Weapon Physics Programs. Advances in fast pulsed power technology and in z-pinch hohlraums on Sandia National Laboratories` Z Accelerator provide sufficient basis for pursuing the development of X-1. The X-1 plan follows a strategy based on scaling the 2 MJ x-ray output on Z via a 3-fold increase in z-pinch load current. The large volume (>5 cm{sup 3}), high temperature (>150 eV), temporally long (>10 ns) hohlraums are unique outside of underground nuclear weapon testing. Analytical scaling arguments and hydrodynamic simulations indicate that these hohlraums at temperatures of 230--300 eV will ignite thermonuclear fuel and drive the reaction to a yield of 200 to 1,000 MJ in the laboratory. X-1 will provide the high-fidelity experimental capability to certify the survivability and performance of non-nuclear weapon components in hostile radiation environments. Non-ignition sources will provide cold x-ray environments (<15 keV), and high yield fusion burn sources will provide high fidelity warm x-ray environments (15 keV--80 keV).

  7. Scorpius X-1: The Evolution and Nature of the Twin Compact Radio Lobes

    NASA Astrophysics Data System (ADS)

    Fomalont, E. B.; Geldzahler, B. J.; Bradshaw, C. F.

    2001-09-01

    The motion and variability of the radio components in the low-mass X-ray binary system Sco X-1 have been monitored with extensive VLBI imaging at 1.7 and 5.0 GHz over 4 yr, including a 56 hr continuous VLBI observation in 1999 June. We detect one strong and one weak compact radio component, moving in opposite directions from the radio core. Their relative motion and flux densities are consistent with relativistic effects, from which we derive an average component speed of v/c=0.45+/-0.03 at an angle of 44deg+/-6deg to the line of sight. This inclination of the binary orbit suggests a mass of the secondary star that is less than 0.9 Msolar, assuming a neutron star mass of 1.4 Msolar. We suggest that the two moving radio components consist of ultrarelativistic plasma that is produced at a working surface where the energy in dual-opposing beams disrupt. The radio lobe advance velocity is constant over many hours, but differs among lobe-pairs: 0.32c, 0.46c, 0.48c, and 0.57c. A lobe-pair lifetime is less than 2 days, with a new pair formed near the core within a day. The lobe flux has flux density that is variable over a timescale of 1 hr, has a measured minimum size of 1 mas (4×108 km), and is extended perpendicular to its motion. This timescale and size are consistent with an electron radiative lifetime of less than 1 hr. Such a short lifetime can be caused by synchrotron losses if the lobe magnetic field is 300 G or by adiabatic expansion of the electrons as soon as they are produced at the working surface. The lobes also show periods of slow expansion and a steepening radio spectrum. Two of the core flares are correlated with the lobe flares under the assumption that the flares are produced by an energy burst traveling down the beams with a speed greater than 0.95. The radio morphology for Sco X-1 differs from most other Galactic jet sources. Possible reasons for the morphology difference are that Sco X-1 is associated with a neutron star, it is a persistent X

  8. Along-strike rupture directivity of earthquakes of the 2009 L'Aquila, central Italy, seismic sequence

    NASA Astrophysics Data System (ADS)

    Calderoni, G.; Rovelli, A.; Ben-Zion, Y.; Di Giovambattista, R.

    2015-10-01

    We perform a systematic investigation of along-strike rupture directivity of 70 earthquakes (3.0 ≤ Mw ≤ 6.1) of the 2009 L'Aquila seismic sequence by analysing azimuthal variations of broad-band seismograms recorded in the distance range 60 km < R < 230 km. We use reference spectra of events with little directivity (similar to the empirical Green's function method) to deconvolve propagation-site effects and focus on source properties. A directivity index (0 ≤ IDIR ≤ 1) calculated for each earthquake quantifies the spectral separation above the corner frequency of the target event at opposite along-strike directions. A large number (73 per cent) of events including the Mw 6.1 main shock show high (>0.7) IDIR values indicating predominantly unilateral rupture propagation. The preferred rupture propagation direction is generally to the southeast with no dependence on the earthquake magnitude or occurrence time. Events on two main faults (L'Aquila and Campotosto) show somewhat different behaviour. Almost all earthquakes on the L'Aquila fault have strong unilateral directivity to the southeast, whereas earthquakes on the Campotosto fault show more diverse behaviour. However, there is a predominance of unilateral ruptures (14 out of 22) also on the Campotosto fault, and the few (five) earthquakes with ruptures to the northwest are limited to the most northwestern segment of the fault. The spectral results are consistent with time-domain analysis when the latter samples adequately the frequency band above corner frequency. The preferred rupture direction may be produced at least in part by a velocity contrast across the fault. The results provide important input for estimates of seismic motion and physics of earthquake ruptures.

  9. PHOEBE: PHysics Of Eclipsing BinariEs

    NASA Astrophysics Data System (ADS)

    Prsa, Andrej; Matijevic, Gal; Latkovic, Olivera; Vilardell, Francesc; Wils, Patrick

    2011-06-01

    PHOEBE (PHysics Of Eclipsing BinariEs) is a modeling package for eclipsing binary stars, built on top of the widely used WD program (Wilson & Devinney 1971). This introductory paper overviews most important scientific extensions (incorporating observational spectra of eclipsing binaries into the solution-seeking process, extracting individual temperatures from observed color indices, main-sequence constraining and proper treatment of the reddening), numerical innovations (suggested improvements to WD's Differential Corrections method, the new Nelder & Mead's downhill Simplex method) and technical aspects (back-end scripter structure, graphical user interface). While PHOEBE retains 100% WD compatibility, its add-ons are a powerful way to enhance WD by encompassing even more physics and solution reliability.

  10. Deep electromagnetic investigations after April 6, 2009 earthquake to characterize the L’Aquila Basin

    NASA Astrophysics Data System (ADS)

    Balasco, M.; Giocoli, A.; Gueguen, E.; Lapenna, V.; Perrone, A.; Piscitelli, S.; Rizzo, E.; Romano, G.; Siniscalchi, A.; Votta, M.

    2009-12-01

    In consequence of the strong earthquake occurred in the Abruzzo region (Central Italy) on April 6, 2009 with magnitude Mw=6.3, two different type of geophysical investigation, magnetotelluric (MT) and Deep Electrical Resistivity Tomography (DERT), have been carried out across the Aterno Valley. The purpose of this type of deep geophysical exploration has been to characterize a wide portion of the subsurface defying the thickness and the geometric relationships between the quaternary deposits and the deeper mesocenozoic bedrock of the L’Aquila basin and the electrical structure at seismogenic depth. The MT surveys were carried out along a profile about 20 km long crossing the villages of Bagno (SW) and Paganica (NE) and placed in the epicentral zones of the aftershocks which is an area (30 km long and 10 km large) parallel to Apennine chain and oriented in NW-SE direction. The MT soundings were performed by MT24-LF systems (Schlumberger/EMI) installed in 15 different locations along the profile with a minimum site separations of 1 km. The frequency of data recording was set to 6.25 Hz for at least 24 hours and during night-time we launched high frequency sampling acquisition events (500 Hz) for at least 2 hour. Time series data were analyzed using the processing based on Egbert’s robust code to compute estimates of the MT transfer function in the period range 0.00931-238.313 s. Dimensionality and directionality analysis have been performed before the application of an inversion 2D routine to obtain the resistivity distribution of subsoil, as function of depth. Almost coincident with MT profile, a DERT with “dipole-dipole” array configuration has been carried out along a profile of 8 km between Bagno and Paganica villages, using 21 stations with an electrode spacing of 400 m and a maximum distance between current and potential probes 7-8 times the basic spacing. In this way, the electrode array geometry allows us to obtain an exploration depth of about 900 m

  11. A new Wolf-Rayet star and its circumstellar nebula in Aquila

    NASA Astrophysics Data System (ADS)

    Gvaramadze, V. V.; Kniazev, A. Y.; Hamann, W.-R.; Berdnikov, L. N.; Fabrika, S.; Valeev, A. F.

    2010-04-01

    We report the discovery of a new Wolf-Rayet star in Aquila via detection of its circumstellar nebula (reminiscent of ring nebulae associated with late WN stars) using the Spitzer Space Telescope archival data. Our spectroscopic follow-up of the central point source associated with the nebula showed that it is a WN7h star (we named it WR121b). We analysed the spectrum of WR121b by using the Potsdam Wolf-Rayet model atmospheres, obtaining a stellar temperature of ~=50kK. The stellar wind composition is dominated by helium with ~20 per cent of hydrogen. The stellar spectrum is highly reddened [E(B - V) = 2.85mag]. Adopting an absolute magnitude of Mv = -5.7, the star has a luminosity of logL/Lsolar = 5.75 and a mass-loss rate of 10-4.7Msolaryr-1, and resides at a distance of 6.3kpc. We searched for a possible parent cluster of WR121b and found that this star is located at ~=1° from the young star cluster embedded in the giant HII region W43 (containing a WN7+a/OB? star - WR121a). We also discovered a bow shock around the O9.5III star ALS9956, located at from the cluster. We discuss the possibility that WR121b and ALS9956 are runaway stars ejected from the cluster in W43. Based on observations collected at the German-Spanish Astronomical Center, Calar Alto, jointly operated by the Max-Planck-Institut für Astronomie Heidelberg and the Instituto de Astrofísica de Andalucía (CSIC). E-mail: vgvaram@mx.iki.rssi.ru (VVG); akniazev@saao.ac.za (AYK); wrh@astro.physik.uni-potsdam.de (WRH); berdnik@sai.msu.ru (LNB); fabrika@sao.ru (SF); azamat@sao.ru (AFV)

  12. Modeling Late-Summer Distribution of Golden Eagles (Aquila chrysaetos) in the Western United States.

    PubMed

    Nielson, Ryan M; Murphy, Robert K; Millsap, Brian A; Howe, William H; Gardner, Grant

    2016-01-01

    Increasing development across the western United States (USA) elevates concerns about effects on wildlife resources; the golden eagle (Aquila chrysaetos) is of special concern in this regard. Knowledge of golden eagle abundance and distribution across the western USA must be improved to help identify and conserve areas of major importance to the species. We used distance sampling and visual mark-recapture procedures to estimate golden eagle abundance from aerial line-transect surveys conducted across four Bird Conservation Regions in the western USA between 15 August and 15 September in 2006-2010, 2012, and 2013. To assess golden eagle-habitat relationships at this scale, we modeled counts of golden eagles seen during surveys in 2006-2010, adjusted for probability of detection, and used land cover and other environmental factors as predictor variables within 20-km2 sampling units randomly selected from survey transects. We found evidence of positive relationships between intensity of use by golden eagles and elevation, solar radiation, and mean wind speed, and of negative relationships with the proportion of landscape classified as forest or as developed. The model accurately predicted habitat use observed during surveys conducted in 2012 and 2013. We used the model to construct a map predicting intensity of use by golden eagles during late summer across our ~2 million-km2 study area. The map can be used to help prioritize landscapes for conservation efforts, identify areas where mitigation efforts may be most effective, and identify regions for additional research and monitoring. In addition, our map can be used to develop region-specific (e.g., state-level) density estimates based on the latest information on golden eagle abundance from a late-summer survey and aid designation of geographic management units for the species. PMID:27556735

  13. Relationship between mastication and cognitive function in elderly in L’Aquila

    PubMed Central

    Mummolo, Stefano; Ortu, Eleonora; Necozione, Stefano; Monaco, Annalisa; Marzo, Giuseppe

    2014-01-01

    Patients with cognitive deficit have poor oral health and fewer teeth than cognitive normal elderly. The aim of the study was to investigate potential differences in masticatory function between elderly with dementia and those with normal cognitive function. Fifty-five patients (age >61; 82.05 ± 3.53) were enrolled in the study. Twenty-five subjects cognitively normal (10 females/15 males; 81.04 ± 4.89 years), were randomly selected and were assigned to Control Group. Thirty subjects (15 females/15 males; 83.16 ± 6.017 with cognitive impairments were randomly selected from hospitalized patients (Medically Assisted Residences RSA) and were assigned to Test Group. MMSE test, B-ADL and number of teeth were evaluated for each subject. The number of teeth in relation to levels of schooling is not resulted significative. In the cognitively impaired group 26 subjects had fewer than 20 teeth (86.6%); in the cognitively normal group 9 subjects had fewer than 20 teeth (36%). The correlation between number of teeth and age in both groups is significative (p<0.05). There is also a significative correlation between subjects with renal diseases and type II diabetes and number of teeth (p<0.05). Finally a significative correlation is present between number of teeth and sex of the patients (p<0.05) (Table 1). The results of the Wilcoxon’s test revealed a significative correlation between MMSE in the two groups (p<0.01). There is also a significative correlation between the two groups and the educational background (p<0.01). The results of the study shows a clear correlation between tooth loss and cognitive function in elderly of L’Aquila. PMID:24955179

  14. Modeling Late-Summer Distribution of Golden Eagles (Aquila chrysaetos) in the Western United States

    PubMed Central

    Gardner, Grant

    2016-01-01

    Increasing development across the western United States (USA) elevates concerns about effects on wildlife resources; the golden eagle (Aquila chrysaetos) is of special concern in this regard. Knowledge of golden eagle abundance and distribution across the western USA must be improved to help identify and conserve areas of major importance to the species. We used distance sampling and visual mark-recapture procedures to estimate golden eagle abundance from aerial line-transect surveys conducted across four Bird Conservation Regions in the western USA between 15 August and 15 September in 2006–2010, 2012, and 2013. To assess golden eagle-habitat relationships at this scale, we modeled counts of golden eagles seen during surveys in 2006–2010, adjusted for probability of detection, and used land cover and other environmental factors as predictor variables within 20-km2 sampling units randomly selected from survey transects. We found evidence of positive relationships between intensity of use by golden eagles and elevation, solar radiation, and mean wind speed, and of negative relationships with the proportion of landscape classified as forest or as developed. The model accurately predicted habitat use observed during surveys conducted in 2012 and 2013. We used the model to construct a map predicting intensity of use by golden eagles during late summer across our ~2 million-km2 study area. The map can be used to help prioritize landscapes for conservation efforts, identify areas where mitigation efforts may be most effective, and identify regions for additional research and monitoring. In addition, our map can be used to develop region-specific (e.g., state-level) density estimates based on the latest information on golden eagle abundance from a late-summer survey and aid designation of geographic management units for the species. PMID:27556735

  15. The Mitochondrial Genomes of Aquila fasciata and Buteo lagopus (Aves, Accipitriformes): Sequence, Structure and Phylogenetic Analyses

    PubMed Central

    Jiang, Lan; Chen, Juan; Wang, Ping; Ren, Qiongqiong; Yuan, Jian; Qian, Chaoju; Hua, Xinghong; Guo, Zhichun; Zhang, Lei; Yang, Jianke; Wang, Ying; Zhang, Qin; Ding, Hengwu; Bi, De; Zhang, Zongmeng; Wang, Qingqing; Chen, Dongsheng; Kan, Xianzhao

    2015-01-01

    The family Accipitridae is one of the largest groups of non-passerine birds, including 68 genera and 243 species globally distributed. In the present study, we determined the complete mitochondrial sequences of two species of accipitrid, namely Aquila fasciata and Buteo lagopus, and conducted a comparative mitogenome analysis across the family. The mitogenome length of A. fasciata and B. lagopus are 18,513 and 18,559 bp with an A + T content of 54.2% and 55.0%, respectively. For both the two accipitrid birds mtDNAs, obvious positive AT-skew and negative GC-skew biases were detected for all 12 PCGs encoded by the H strand, whereas the reverse was found in MT-ND6 encoded by the L strand. One extra nucleotide‘C’is present at the position 174 of MT-ND3 gene of A. fasciata, which is not observed at that of B. lagopus. Six conserved sequence boxes in the Domain II, named boxes F, E, D, C, CSBa, and CSBb, respectively, were recognized in the CRs of A. fasciata and B. lagopus. Rates and patterns of mitochondrial gene evolution within Accipitridae were also estimated. The highest dN/dS was detected for the MT-ATP8 gene (0.32493) among Accipitridae, while the lowest for the MT-CO1 gene (0.01415). Mitophylogenetic analysis supported the robust monophyly of Accipitriformes, and Cathartidae was basal to the balance of the order. Moreover, we performed phylogenetic analyses using two other data sets (two mitochondrial loci, and combined nuclear and mitochondrial loci). Our results indicate that the subfamily Aquilinae and all currently polytypic genera of this subfamily are monophyletic. These two novel mtDNA data will be useful in refining the phylogenetic relationships and evolutionary processes of Accipitriformes. PMID:26295156

  16. Satellite tracking of two lesser spotted eagles Aquila pomarina, migrating from Namibia

    USGS Publications Warehouse

    Meyburg, B.-U.; Ellis, D.H.; Meyburg, C.; Mendelsohn, J.; Scheller, W.

    2001-01-01

    One immature and one subadult Lesser Spotted Eagle, Aquila pomarina, were followed by satellite telemetry from their non-breeding areas in Namibia. Both birds were fitted with transmitters (PTTs) in February 1994 and tracked, the immature for six months and two weeks, over distances of 10084 and 16773 km, respectively. During their time in Namibia both birds? movements were in response to good local rainfall. The immature eagle left Namibia at the end of February, the subadult at the end of March. They flew to their respective summer quarters in Hungary and the Ukraine, arriving there 2.5 and 1.5 months later than the breeding adults. The immature eagle took over two months longer on the homeward journey than a breeding male followed by telemetry in a previous study. On returning, the immature eagle followed the narrow flightpath through Africa used by other Lesser Spotted Eagles on their outward migration. It reached this corridor, which runs roughly between longitudes 31? and 36? East from Suez to Lake Tanganyika, veering from the shortest route in a direction east-northeast through Angola and Zambia to the southern end of Lake Tanganyika. The route taken by the subadult bird on its return migration differed markedly from that of all Lesser Spotted Eagles tracked to date, running further west through the Democratic Republic of Congo where, level with the equator, it flew over the eastern rainforest of that country. The outward migration, however, followed the same corridor and coincided in time with the migration of adults.

  17. Satellite tracking of two Lesser Spotted Eagles, Aquila pomarina, migrating from Namibia

    USGS Publications Warehouse

    Meyburg, B.-U.; Ellis, D.H.; Meyburg, C.; Mendelsohn, J.M.; Scheller, W.

    2001-01-01

    One immature and one subadult Lesser Spotted Eagle, Aquila pomarina, were followed by satellite telemetry from their nonbreeding areas in Namibia. Both birds were fitted with transmitters (PTTs) in February 1994 and tracked, the immature for six months and three weeks, the subadult for eight months and two weeks, over distances of 10 084 and 16 773 km, respectively. During their time in Namibia both birds' movements were in response to good local rainfall. The immature eagle left Namibia at the end of February, the subadult at the end of March. They flew to their respective summer quarters in Hungary and the Ukraine, arriving there 2.5 and 1.5 months later than the breeding adults. The immature eagle took over two months longer on the homeward journey than a breeding male followed by telemetry in a previous study. On returning, the immature eagle followed the narrow flightpath through Africa used by other Lesser Spotted Eagles on their outward migration. It reached this corridor, which runs roughly between longitudes 31?? and 36?? East from Suez to Lake Tanganyika, veering from the shortest route in a direction east-northeast through Angola and Zambia to the southern end of Lake Tanganyika. The route taken by the subadult bird on its return migration differed markedly from that of all Lesser Spotted Eagles tracked to date, running further west through the Democratic Republic of Congo where, level with the equator, it flew over the eastern rainforest of that country. The outward migration, however, followed the same corridor and coincided in time with the migration of adults. [A German translation of the abstract is provided on p. 40.].

  18. The reflection component from Cygnus X-1 in the soft state measured by NuSTAR and Suzaku

    SciTech Connect

    Tomsick, John A.; Boggs, Steven E.; Craig, William W.; Nowak, Michael A.; Parker, Michael; Fabian, Andy C.; Miller, Jon M.; King, Ashley L.; Harrison, Fiona A.; Forster, Karl; Fürst, Felix; Grefenstette, Brian W.; Madsen, Kristin K.; Bachetti, Matteo; Barret, Didier; Christensen, Finn E.; Hailey, Charles J.; Natalucci, Lorenzo; Pottschmidt, Katja; Ross, Randy R.; and others

    2014-01-01

    The black hole binary Cygnus X-1 was observed in late 2012 with the Nuclear Spectroscopic Telescope Array (NuSTAR) and Suzaku, providing spectral coverage over the ∼1-300 keV range. The source was in the soft state with a multi-temperature blackbody, power law, and reflection components along with absorption from highly ionized material in the system. The high throughput of NuSTAR allows for a very high quality measurement of the complex iron line region as well as the rest of the reflection component. The iron line is clearly broadened and is well described by a relativistic blurring model, providing an opportunity to constrain the black hole spin. Although the spin constraint depends somewhat on which continuum model is used, we obtain a {sub *} > 0.83 for all models that provide a good description of the spectrum. However, none of our spectral fits give a disk inclination that is consistent with the most recently reported binary values for Cyg X-1. This may indicate that there is a >13° misalignment between the orbital plane and the inner accretion disk (i.e., a warped accretion disk) or that there is missing physics in the spectral models.

  19. Catching Up on State Transitions in Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Boeck, Moritz; Hanke, Manfred; Wilms, Joern; Pirner, Stefan; Grinberg, Victoria; Markoff, Sera; Pottschmidt, Katja; Nowak, Michael A.; Pooley, Guy

    2008-01-01

    In 2005 February we observed Cygnus X-1 over a period of 10 days quasi-continuously with the Rossi X-ray Timing Explorer and the Ryle telescope. We present the results of the spectral and timing analysis on a timescale of 90 min and show that the behavior of Cyg X-1 is similar to that found during our years long monitoring campaign. As a highlight we present evidence for a full transition from the hard to the soft state that happened during less than three hours. The observation provided a more complete picture of a state transition than before, especially concerning the evolution of the time lags, due to unique transition coverage and analysis with high time resolution.

  20. High Resolution Spectroscopy of the LMXB SCO X-1

    NASA Astrophysics Data System (ADS)

    Canizares, Claude

    2002-09-01

    Sco X-1 is by far the brightest persistent extrasolar X-ray source in the sky. Early observations showed a bright X-ray continuum and strong K (Fe XXV) line emission. The source has been well established as an LMXB Z-source spending most of its time on the so-called flaring branch. Low energy line emission has been detected in the EINSTEIN OGS, which most likely arises from a photoionized ADC. Through its variable radio emission it was established as a Galactic-jet radio source with strong similarities to luminous radio galaxies and quasars and we expect to observe P Cygni lines from a strong disk wind as observed in Cir X-1. We developed a specific observation strategy that allows to safely observe the source with the Chandra HETGS.

  1. The X-ray halo of Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Bode, M. F.; Norwell, G. A.; Priedhorsky, W. C.; Evans, A.

    1985-01-01

    Four Einstein HRI images of Cygnus X-1 were examined for the presence of a halo due to scattering of X-rays by interstellar grains. The analysis technique exploits the intrinsic aperiodic variability of the source to map the point response function of the optics. A residual, nonvariable component to the surface brightness distribution (comprising approximately more than 12 percent of the source flux) is interpreted as a scattered halo. The halo flux does not reflect the short term time variability of the central source as it is smoothed by differential time delays of order days. The Cygnus X-1 halo is consistent with those of other sources derived in previous studies using different techniques. Comparison is made with a scattering model, and the sensitivity of the halo flux to maximal grain size is demonstrated.

  2. Long-Term Observations of Her X-1 with BATSE

    NASA Technical Reports Server (NTRS)

    Wilson, R. B.; Scott, D. M.; Finger, M. H.

    1991-01-01

    Pulsed emission from Her X-1 has been observed by BATSE during each Main High state throughout the CGRO (Compton Gamma-Ray Observatory) mission . This long observation set by a single instrument provides new information on long-term behavior of the Her X-1 system. The luminosity varies by more than a factor of 3 between different 35d cycles. Frequency and flux histories do not show a simple relationship between the source intensity and spin behavior, but do show that only spindown occurs when the source is in its lowest intensity state. Orbital analyses will be presented, including tests for consistency of the observed orbital epoch with the long-term ephemeris reported by (Deeter 1991). The intensity profile and onset times of cycles observed by both BATSE and the RXTE ASM (All Sky Monitor) will be compared. Behavior of the cycle start times versus source Main High peak intensity will be presented.

  3. Cygnus X-1: Dips and Low Frequency Noise

    NASA Technical Reports Server (NTRS)

    Wilms, Joern

    2000-01-01

    The primary science result to come out of this work is the discovery that the time lags between hard and soft variability in Cyg X-1 show dramatic spikes during the transitions between hard and soft states (and possibly during "failed transitions" to the soft state), but are remarkably similar between the main soft and hard states. This work is being continued and elaborated upon with ongoing RXTE monitoring campaigns.

  4. RXTE Observations of LMC X-1 and LMC X-3

    NASA Technical Reports Server (NTRS)

    Wilms, J.; Nowak, M. A.; Dove, J. B.; Pottschmidt, K.; Heindl, W. A.; Begelman, M. C.; Staubert, R.

    1998-01-01

    Of all known persistent stellar-mass black hole candidates, only LMC X-1 and LMC X-3 consistently show spectra that are dominated by a soft, thermal component. We present results from long (170 ksec) Rossi X-ray Timing Explorer (RXTE) observations of LMC X-1 and LMC X-3 made in 1996 December. The spectra can be described by a multicolor disk blackbody plus an additional high-energy power-law. Even though the spectra are very soft (Gamma approximately 2.5), RXTE detected a significant signal from LMC X-3 up to energies of 50 keV, the hardest energy at which the object was ever detected. Focusing on LMC X-3, we present results from the first year of an ongoing monitoring campaign with RXTE which started in 1997 January. We show that the appearance of the object changes considerably over its approximately 200d long cycle. This variability can either be explained by periodic changes in the mass transfer rate or by a precessing accretion disk analogous to Her X-1.

  5. RXTE Observations of LMC X-1 and LMC X-3

    NASA Technical Reports Server (NTRS)

    Wilms, J.; Nowak, M. A.; Dove, J. B.; Pottschmidt, K.; Heindl, W. A.; Begelman, M. C.; Staubert, R.

    1999-01-01

    Of all known persistent stellar-mass black hole candidates, only LMC X-1 and LMC X-3 consistently show spectra that are dominated by a soft, thermal component. We present results from long (170 ksec) Rossi X-ray Timing Explorer (RXTE) observations of LMC X-1 and LMC X-3 made in 1996 December. The spectra can be described by a multicolor disk blackbody plus an additional high-energy power-law. Even though the spectra are very soft (Gamma approximately 2.5), RXTE detected a significant signal from LMC X-3 up to energies of 50 keV, the hardest energy at which the object was ever detected. Focusing on LMC X-3 , we present results from the first year of an ongoing monitoring campaign with RXTE which started in 1997 January. We show that the appearance of the object changes considerably over its approximately 200 d long cycle. This variability can either be explained by periodic changes in the mass transfer rate or by a precessing accretion disk analogous to Her X-1.

  6. The Distance and Milliarcsecond Radio Structure of Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Bradshaw, C. F.; Fomalont, E. B.; Geldzahler, B. J.

    1997-07-01

    From three VLBA observations at 5 GHz, taken over 13 months, we have measured the trigonometric parallax of Sco X-1 as 0.00023" +/- 0.00028" hence, its distance is greater than 1300 pc. This supports the hypothesis that Sco X-1 radiates at or near the Eddington limit at the transition point between the normal and flaring branches of the X-ray color-color diagram. These results suggest that Sco X-1 and other Z-type quasi-periodic oscillators have a well defined luminosity and can be used as X-ray standard candles. All three VLBA observations contain a radio core of flux density 0.5 mJy and size greater than 4 mas. However, the third VLBA observation revealed two additional radio components (separated by 12 mas and on opposite sides of the radio core) not present in the two previous observations. The evolution of these two components will remain unknown until multiepoch radio imaging and coordinated radio and X-ray total flux density measurements can be made.

  7. PTSD Growth and Substance Abuse Among a College Student Community: Coping Strategies after 2009 L'aquila Earthquake.

    PubMed

    Bianchini, V; Roncone, R; Giusti, L; Casacchia, M; Cifone, M G; Pollice, R

    2015-01-01

    Aim of the study was the assessment of coping strategies, specifically substance use and post-traumatic growth (PTG), in 411 college students two years after 2009 L'Aquila earthquake. Post-Traumatic Growth Inventory (PTGI) was used to assess PTG and one question about substance use (alcohol, tobacco, cannabis) was asked to verify if students had modified their use in the post-earthquake compared with the pre-earthquake period. The 77.1% of college students were exposed to L'Aquila earthquake. The PTGI mean score was 35.23, underlining low positive coping strategies among student community. About substance abuse, the 43.8% of college students reported a marked increase in alcohol use, 7.8% in cannabis and the 15.8% reported an increase in nicotine use in the post-earthquake period. Despite these data, 12.5 % of the students reported a decrease in alcohol use after the earthquake and 17.3% of the sample reported a PTG, showing positive behaviors and attitudes after the traumatic experience of the natural disaster (increase of social relationships, appreciation of new future possibilities, and development of a new deep meaning of life). Inferential analysis shows a strong negative correlation between direct earthquake exposure and PTGI total score. In post-disaster settings, a systematic framework of case identification, triage, and mental health interventions, including the improvement of positive coping strategies, like the PTG, should be integrated into emergency medicine and trauma care responses. PMID:25893001

  8. OXA-23 carbapenemase in multidrug-resistant Acinetobacter baumannii ST2 type: first identification in L'Aquila Hospital (Italy).

    PubMed

    Perilli, Mariagrazia; Sabatini, Alessia; Pontieri, Eugenio; Celenza, Giuseppe; Segatore, Bernardetta; Bottoni, Carlo; Bellio, Pierangelo; Mancini, Alisia; Marcoccia, Francesca; Brisdelli, Fabrizia; Amicosante, Gianfranco

    2015-02-01

    In this study 114 extensively drug-resistant Acinetobacter baumannii clinical isolates were characterized. The strains were collected at L'Aquila Hospital after the earthquake in L'Aquila city (central Italy) on the 6th of April 2009. The genes blaOXA-23 and blaOXA-51 were detected in all clinical isolates analyzed, whereas blaTEM-1 allele was detected in 56/114 isolates. The blaOXA-23 gene is located downstream the ISAba region and is under control of a strong promoter. On 42/80 A. baumannii the presence of two class 1 integrons was ascertained on chromosomal DNA. Variable regions show different gene array: (1) aadB and aadA2, (2) aacA4, aac(6')-Ib-cr, and aadA1. Macrorestriction analysis using ApaI restriction endonuclease identifies three clusters (A, B, and C) according to pulsed-field gel electrophoresis profiles. All isolates analyzed belong to the clone A. baumannii sequence type 2. PMID:25275951

  9. Detecting earthquake damage in urban area: application to COSMO-SkyMed imagery of L'Aquila earthquake

    NASA Astrophysics Data System (ADS)

    Anniballe, R.; Chini, M.; Pierdicca, N.; Bignami, C.; Stramondo, S.; Noto, F.; Scalia, T.; Martinelli, A.; Mannella, A.

    2015-10-01

    Due to the improved spatial resolution, Earth observation (EO) data, either from Synthetic Aperture Radar (SAR) or optical sensor, provide the opportunity to assess earthquake damage of individual buildings. However, the operational use of EO data for earthquake damage mapping is basically limited to the visual inspection of Very High Resolution (VHR) optical imagery. In this work we investigate the feasibility of a damage assessment product at single building scale from a pair of VHR SAR images acquired before and after a seismic event. We perform the change analysis using the Kullbach-Leibler divergence and the intensity ratio and then we associate detected changes to a building map provided as GIS layer. Finally the expected SAR signature of a collapsed building is considered to identify severely damaged buildings. In order to test the proposed methodology we use Spotlight COSMO-SkyMed SAR imagery of L'Aquila (Italy) collected before and after the earthquake occurred on April 6, 2009. A macroseismic survey on the whole central area of L'Aquila city based on the European Macroseismic Scale 1998 is used to assess the capability of VHR SAR images to map damage.

  10. PTSD Growth and Substance Abuse Among a College Student Community: Coping Strategies after 2009 L’aquila Earthquake

    PubMed Central

    Bianchini, V; Roncone, R; Giusti, L; Casacchia, M; Cifone, MG; Pollice, R

    2015-01-01

    Aim of the study was the assessment of coping strategies, specifically substance use and post-traumatic growth (PTG), in 411 college students two years after 2009 L’Aquila earthquake. Post-Traumatic Growth Inventory (PTGI) was used to assess PTG and one question about substance use (alcohol, tobacco, cannabis) was asked to verify if students had modified their use in the post-earthquake compared with the pre-earthquake period. The 77.1% of college students were exposed to L’Aquila earthquake. The PTGI mean score was 35.23, underlining low positive coping strategies among student community. About substance abuse, the 43.8% of college students reported a marked increase in alcohol use, 7.8% in cannabis and the 15.8% reported an increase in nicotine use in the post-earthquake period. Despite these data, 12.5 % of the students reported a decrease in alcohol use after the earthquake and 17.3% of the sample reported a PTG, showing positive behaviors and attitudes after the traumatic experience of the natural disaster (increase of social relationships, appreciation of new future possibilities, and development of a new deep meaning of life). Inferential analysis shows a strong negative correlation between direct earthquake exposure and PTGI total score. In post-disaster settings, a systematic framework of case identification, triage, and mental health interventions, including the improvement of positive coping strategies, like the PTG, should be integrated into emergency medicine and trauma care responses. PMID:25893001

  11. Preceding Hard Flares in the Outburst Rise of Aql X-1: A Link to Black Hole State Transitions

    NASA Astrophysics Data System (ADS)

    Yu, W.; Klein-Wolt, M.; Fender, R.; van der Klis, M.

    2003-03-01

    We have discovered preceding hard flares ( > 15 keV) in the 1999 May/June and the 2000 September/October outbursts of Aql X-1. The energy spectra were dominanted by a power-law component during the hard flares and transited to a much softer spectrum immediately following the hard flare decay. At the same time, the Fourier power spectra transited from a combination of a band-limited noise and a 1-20 Hz QPO to a simple power-law noise. The spectra/timing state transitions were very similar to those Low/Hard--to--High/Soft state transitions observed in the outburst rise of black hole SXTs, e.g. XTE J1550-564 and XTE J1859+226. As the outburst mechanism is probably the same in both neutron star and black hole SXTs, the preceding hard flares and the associated spectral/timing state transitions are probably of the same origin in Aql X-1 and the black hole SXTs. This estabilishes a link between neutron star and black hole spectral/timing states. The association of the QPO and the band-limited noise in Aql X-1 with those in black hole SXTs confirms the frequency correlation between QPO and noise break previously found for many neutron star and black hole X-ray binaries in a wide frequency range. We discuss the impact of these results to our research in the SXT outburst mechanism, the black hole state transitions and the X-ray variability of X-ray binaries.

  12. Model-based cross-correlation search for gravitational waves from Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Whelan, John T.; Sundaresan, Santosh; Zhang, Yuanhao; Peiris, Prabath

    2015-05-01

    We consider the cross-correlation search for periodic gravitational waves and its potential application to the low-mass x-ray binary Sco X-1. This method coherently combines data not only from different detectors at the same time, but also data taken at different times from the same or different detectors. By adjusting the maximum allowed time offset between a pair of data segments to be coherently combined, one can tune the method to trade off sensitivity and computing costs. In particular, the detectable signal amplitude scales as the inverse fourth root of this coherence time. The improvement in amplitude sensitivity for a search with a maximum time offset of one hour, compared with a directed stochastic background search with 0.25-Hz-wide bins, is about a factor of 5.4. We show that a search of one year of data from the Advanced LIGO and Advanced Virgo detectors with a coherence time of one hour would be able to detect gravitational waves from Sco X-1 at the level predicted by torque balance over a range of signal frequencies from 30 to 300 Hz; if the coherence time could be increased to ten hours, the range would be 20 to 500 Hz. In addition, we consider several technical aspects of the cross-correlation method: We quantify the effects of spectral leakage and show that nearly rectangular windows still lead to the most sensitive search. We produce an explicit parameter-space metric for the cross-correlation search, in general, and as applied to a neutron star in a circular binary system. We consider the effects of using a signal template averaged over unknown amplitude parameters: The quantity to which the search is sensitive is a given function of the intrinsic signal amplitude and the inclination of the neutron-star rotation axis to the line of sight, and the peak of the expected detection statistic is systematically offset from the true signal parameters. Finally, we describe the potential loss of signal-to-noise ratio due to unmodeled effects such as signal

  13. X-Ray Spectral Study of the Photoionized Stellar Wind in Vela X-1

    SciTech Connect

    Watanabe, Shin; Sako, Masao; Ishida, Manabu; Ishisaki, Yoshitaka; Kahn, Steven M.; Kohmura, Takayoshi; Nagase, Fumiaki; Paerels, Frederik; Takahashi, Tadayuki; /JAXA, Sagamihara /KIPAC, Menlo Park /Tokyo Metropolitan U. /Kogakuin U. /Columbia U., Astron. Astrophys.

    2006-07-10

    We present results from quantitative modeling and spectral analysis of the high mass X-ray binary system Vela X-1 obtained with the Chandra High Energy Transmission Grating Spectrometer. The observations cover three orbital phase ranges within a single binary orbit. The spectra exhibit emission lines from H-like and He-like ions driven by photoionization, as well as fluorescent emission lines from several elements in lower charge states. The properties of these X-ray lines are measured with the highest accuracy to date. In order to interpret and make full use of the high-quality data, we have developed a simulator, which calculates the ionization and thermal structure of a stellar wind photoionized by an X-ray source, and performs Monte Carlo simulations of X-ray photons propagating through the wind. The emergent spectra are then computed as a function of the viewing angle accurately accounting for photon transport in three dimensions including dynamics. From comparisons of the observed spectra with results from the simulator, we are able to find the ionization structure and the geometrical distribution of material in the stellar wind of Vela X-1 that can reproduce the observed spectral line intensities and continuum shapes at different orbital phases remarkably well. We find that the stellar wind profile can be represented by a CAK-model with a star mass loss rate of (1.5-2.0) x 10{sup -6} M{sub {circle_dot}} yr{sup -1}, assuming a terminal velocity of 1100 km s{sup -1}. It is found that a large fraction of X-ray emission lines from highly ionized ions are formed in the region between the neutron star and the companion star. We also find that the fluorescent X-ray lines must be produced in at least three distinct regions: (1) the extended stellar wind, (2) reflection off the stellar photosphere, and (3) in a distribution of dense material partially covering and possibly trailing the neutron star, which may be associated with an accretion wake. Finally, from

  14. The smooth cyclotron line in Her X-1 as seen with nuclear spectroscopic telescope array

    SciTech Connect

    Fürst, Felix; Grefenstette, Brian W.; Bellm, Eric C.; Harrison, Fiona; Madsen, Kristin K.; Walton, Dominic J.; Staubert, Rüdiger; Klochkov, Dmitry; Tomsick, John A.; Boggs, Steven E.; Craig, William W.; Bachetti, Matteo; Barret, Didier; Chenevez, Jerome; Christensen, Finn E.; Hailey, Charles J.; Pottschmidt, Katja; Stern, Daniel; Wilms, Jörn; William Zhang

    2013-12-10

    Her X-1, one of the brightest and best studied X-ray binaries, shows a cyclotron resonant scattering feature (CRSF) near 37 keV. This makes it an ideal target for a detailed study with the Nuclear Spectroscopic Telescope Array (NuSTAR), taking advantage of its excellent hard X-ray spectral resolution. We observed Her X-1 three times, coordinated with Suzaku, during one of the high flux intervals of its 35 day superorbital period. This paper focuses on the shape and evolution of the hard X-ray spectrum. The broadband spectra can be fitted with a power law with a high-energy cutoff, an iron line, and a CRSF. We find that the CRSF has a very smooth and symmetric shape in all observations and at all pulse phases. We compare the residuals of a line with a Gaussian optical-depth profile to a Lorentzian optical-depth profile and find no significant differences, strongly constraining the very smooth shape of the line. Even though the line energy changes dramatically with pulse phase, we find that its smooth shape does not. Additionally, our data show that the continuum only changes marginally between the three observations. These changes can be explained with varying amounts of Thomson scattering in the hot corona of the accretion disk. The average, luminosity-corrected CRSF energy is lower than in past observations and follows a secular decline. The excellent data quality of NuSTAR provides the best constraint on the CRSF energy to date.

  15. Case A Binary Evolution

    SciTech Connect

    Nelson, C A; Eggleton, P P

    2001-03-28

    We undertake a comparison of observed Algol-type binaries with a library of computed Case A binary evolution tracks. The library consists of 5500 binary tracks with various values of initial primary mass M{sub 10}, mass ratio q{sub 0}, and period P{sub 0}, designed to sample the phase-space of Case A binaries in the range -0.10 {le} log M{sub 10} {le} 1.7. Each binary is evolved using a standard code with the assumption that both total mass and orbital angular momentum are conserved. This code follows the evolution of both stars until the point where contact or reverse mass transfer occurs. The resulting binary tracks show a rich variety of behavior which we sort into several subclasses of Case A and Case B. We present the results of this classification, the final mass ratio and the fraction of time spent in Roche Lobe overflow for each binary system. The conservative assumption under which we created this library is expected to hold for a broad range of binaries, where both components have spectra in the range G0 to B1 and luminosity class III - V. We gather a list of relatively well-determined observed hot Algol-type binaries meeting this criterion, as well as a list of cooler Algol-type binaries where we expect significant dynamo-driven mass loss and angular momentum loss. We fit each observed binary to our library of tracks using a {chi}{sup 2}-minimizing procedure. We find that the hot Algols display overall acceptable {chi}{sup 2}, confirming the conservative assumption, while the cool Algols show much less acceptable {chi}{sup 2} suggesting the need for more free parameters, such as mass and angular momentum loss.

  16. Discovery of a 115 Day Orbital Period in the Ultraluminous X-ray Source NGC 5408 X-1

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod E.

    2009-01-01

    We report the detection of a 115 day periodicity in SWIFT/XRT monitoring data from the ultraluminous X-ray source (ULX) NGC 5408 X-1. Our o ngoing campaign samples its X-ray flux approximately twice weekly and has now achieved a temporal baseline of ti 485 days. Periodogram ana lysis reveals a significant periodicity with a period of 115.5 +/- 4 days. The modulation is detected with a significance of 3.2 x 10(exp -4) . The fractional modulation amplitude decreases with increasing e nergy, ranging from 0.13 +/- 0.02 above 1 keV to 0.24 +/- 0.02 below 1 keV. The shape of the profile evolves as well, becoming less sharply peaked at higher energies. The periodogram analysis is consistent wi th a periodic process, however, continued monitoring is required to c onfirm the coherent nature of the modulation. Spectral analysis indic ates that NGC 5408 X-1 can reach 0.3 - 10 keV luminosities of approxi mately 2 x 10 40 ergs/s . We suggest that, like the 62 day period of the ULX in M82 (X41.4-1-60), the periodicity detected in NGC 5408 X-1 represents the orbital period of the black hole binary containing the ULX. If this is true then the secondary can only be a giant or super giant star.

  17. Quasi-periodic Oscillations Associated with Spectral Branches in Rossi X-Ray Timing Explorer Observations of Circinus X-1

    NASA Astrophysics Data System (ADS)

    Shirey, Robert E.; Bradt, Hale V.; Levine, Alan M.; Morgan, Edward H.

    1998-10-01

    We present Rossi X-Ray Timing Explorer (RXTE) All-Sky Monitor observations of the X-ray binary Circinus X-1 that illustrate the variety of intensity profiles associated with the 16.55 day flaring cycle of the source. We also present eight observations of Cir X-1 made with the RXTE Proportional Counter Array over the course of a cycle wherein the average intensity of the flaring state decreased gradually over ~12 days. Fourier power density spectra for these observations show a narrow quasi-periodic oscillation (QPO) peak that shifts in frequency between 6.8 and 32 Hz, as well as a broad QPO peak that remains roughly stationary at ~4 Hz. We identify these as Z-source horizontal and normal branch oscillations (HBOs/NBOs), respectively. Color-color and hardness-intensity diagrams (CDs/HIDs) show curvilinear tracks for each of the observations. The properties of the QPOs and very low frequency noise allow us to identify segments of these tracks with Z-source horizontal, normal, and flaring branches that shift location in the CDs and HIDs over the course of the 16.55 day cycle. These results contradict a previous prediction, based on the hypothesis that Cir X-1 is a high-Ṁ atoll source, that HBOs should never occur in this source.

  18. Constraints on the Neutron Star and Inner Accretion Flow in Serpens X-1 Using Nustar

    NASA Technical Reports Server (NTRS)

    Miller, J. M.; Parker, M. L.; Fuerst, F.; Bachetti, M.; Barret, D.; Grefenstette, B. W.; Tendulkar, S.; Harrison, F. A.; Boggs, S. E.; Chakrabarty, D.; Christensen, F. E.; Craig, W. W.; Fabian, A. C.; Hailey, C. J.; Natalucci, L.; Paerels, F.; Rana, V.; Stern, D. K.; Tomsick, J. A.; Zhang, Will

    2013-01-01

    We report on an observation of the neutron star low-mass X-ray binary Serpens X-1, made with NuSTAR. The extraordinary sensitivity afforded by NuSTAR facilitated the detection of a clear, robust, relativistic Fe K emission line from the inner disk. A relativistic profile is required over a single Gaussian line from any charge state of Fe at the 5 sigma level of confidence, and any two Gaussians of equal width at the same confidence. The Compton back-scattering "hump" peaking in the 10-20 keV band is detected for the first time in a neutron star X-ray binary. Fits with relativistically blurred disk reflection models suggest that the disk likely extends close to the innermost stable circular orbit (ISCO) or stellar surface. The best-fit blurred reflection models constrain the gravitational redshift from the stellar surface to be ZnS (is) greater than 0.16. The data are broadly compatible with the disk extending to the ISCO; in that case,ZnS(is) greater than 0.22 and RNS (is) less than12.6 km (assuming MnS = 1.4 solar mass and a = 0, where a = cJ/GM2). If the star is as large or larger than its ISCO, or if the effective reflecting disk leaks across the ISCO to the surface, the redshift constraints become measurements. We discuss our results in the context of efforts to measure fundamental properties of neutron stars, and models for accretion onto compact objects.

  19. Ultra Low Frequency (ULF) European multi station magnetic field analysis before and during the 2009 earthquake at L'Aquila regarding regional geotechnical information

    NASA Astrophysics Data System (ADS)

    Prattes, G.; Schwingenschuh, K.; Eichelberger, H. U.; Magnes, W.; Boudjada, M.; Stachel, M.; Vellante, M.; Villante, U.; Wesztergom, V.; Nenovski, P.

    2011-07-01

    This work presents ground based Ultra Low Frequency (ULF) magnetic field measurements in the frequency range from 10-15 mHz from 1 January 2008 to 14 April 2009. In this time period a strong earthquake series hit the Italian Abruzzo region around L'Aquila with the main stroke of magnitude M = 6.3 on 6 April 2009. In the frame of the South European Geomagnetic Array (SEGMA), a European collaboration runs ULF fluxgate instruments providing continuously magnetic field data recorded in mid- and south Europe. The main scientific objective is the investigation of signal variations due to seismic activity and the discrimination between other natural and human influences. The SEGMA station closest to the L'Aquila earthquake epicenter is L'Aquila observatory located in the epicenter region. For the scientific analysis we extract the nighttime period from 22:00-02:00 UT and determine the power spectral density (PSD) of the horizontal (H) and vertical (Z) magnetic field components and the standardized polarization ratio (Z) over (H). To discriminate local emissions from global geomagnetic effects, data from three SEGMA stations in distances up to 630 km from the epicenter region are analyzed and further compared to the independent global geomagnetic ∑ Kp index. Apart from indirect ionospheric effects, electromagnetic noise could be originated in the lithosphere due to tectonic mechanisms in the earthquake focus. To estimate the amplitude of assumed lithospheric electromagnetic noise emissions causing anomalies in the PSD of the (Z) component, we consider magnetotelluric calculations of the electric crust conductivity in the L'Aquila region. Results found at L'Aquila observatory are interpreted with respect to the lithosphere electrical conductivity in the local observatory region, the ∑ Kp index, and further in a multi station analysis. Possible seismic related ULF anomalies occur ~2 weeks before the main stroke.

  20. Probing the stellar wind environment of Vela X-1 with MAXI

    NASA Astrophysics Data System (ADS)

    Malacaria, C.; Mihara, T.; Santangelo, A.; Makishima, K.; Matsuoka, M.; Morii, M.; Sugizaki, M.

    2016-04-01

    Context. Vela X-1 is one of the best-studied and most luminous accreting X-ray pulsars. The supergiant optical companion produces a strong radiatively driven stellar wind that is accreted onto the neutron star, producing highly variable X-ray emission. A complex phenomenology that is due to both gravitational and radiative effects needs to be taken into account to reproduce orbital spectral variations. Aims: We have investigated the spectral and light curve properties of the X-ray emission from Vela X-1 along the binary orbit. These studies allow constraining the stellar wind properties and its perturbations that are induced by the pulsating neutron star. Methods: We took advantage of the All Sky Monitor MAXI/GSC data to analyze Vela X-1 spectra and light curves. By studying the orbital profiles in the 4-10 and 10-20 keV energy bands, we extracted a sample of orbital light curves (~15% of the total) showing a dip around the inferior conjunction, that is, a double-peaked shape. We analyzed orbital phase-averaged and phase-resolved spectra of both the double-peaked and the standard sample. Results: The dip in the double-peaked sample needs NH ~ 2 × 1024cm-2 to be explained by absorption alone, which is not observed in our analysis. We show that Thomson scattering from an extended and ionized accretion wake can contribute to the observed dip. Fit by a cutoff power-law model, the two analyzed samples show orbital modulation of the photon index that hardens by ~0.3 around the inferior conjunction, compared to earlier and later phases. This indicates a possible inadequacy of this model. In contrast, including a partial covering component at certain orbital phase bins allows a constant photon index along the orbital phases, indicating a highly inhomogeneous environment whose column density has a local peak around the inferior conjunction. We discuss our results in the framework of possible scenarios.

  1. The L'Aquila process and the perils of bad communication of science

    NASA Astrophysics Data System (ADS)

    Alberti, Antonio

    2013-04-01

    Responsibilities and observance of ethical behaviour by scientists have increased more than ever with the advancement of science and of the social and economic development of a country. Nowadays, geoscientists are often charged by local and/or national and international authorities with the task of providing ways to foster economic development while protecting human life and safeguarding the environment. But besides technical and scientific expertise, in a democratic country all this requires efficient ways and various channels of scientific divulgation. Geoscientists themselves should be involved in these procedures, or at least they should be called to verify that correct communication is actually released. Unfortunately, it seems that awareness of such new and ever-increasing responsibilities is not yet being always realized at a needed level. The question is especially sensible in Italy, a country in which the hydro-geological, seismological, volcanological and coastal set-up requires careful technical and scientific treatment. Given the fragility of the natural system, the role of geoscientists should not be restricted to the delivery of scientific expertise: in fact, and perhaps more than elsewhere, problems are compounded by the need of communication based on sound science not only to governing authorities, but also to the public at large, possibly including also an array of mass media. Many international organizations have been wrongly interpreting the accusation and especially the sentence at the first stage of the L'Aquila process as a problem of impossibility to predict earthquakes. But the recently published motivation of the sentence seems to have brought to light the lack of a scrupulous overview of the situation prior to the disastrous seismic event, practically leaving the task of public information to the judgment or perception of the national agency in charge of natural hazards. It turned out that a major outcome of the process, apart from the

  2. Space-time distribution of afterslip following the 2009 L'Aquila earthquake

    NASA Astrophysics Data System (ADS)

    D'Agostino, N.; Cheloni, D.; Fornaro, G.; Giuliani, R.; Reale, D.

    2012-02-01

    The inversion of multitemporal DInSAR and GPS measurements unravels the coseismic and postseismic (afterslip) slip distributions associated with the 2009 MW 6.3 L'Aquila earthquake and provides insights into the rheological properties and long-term behavior of the responsible structure, the Paganica fault. Well-resolved patches of high postseismic slip (10-20 cm) appear to surround the main coseismic patch (maximum slip ≈1 m) through the entire seismogenic layer above the hypocenter without any obvious depth-dependent control. Time series of postseismic displacement are well reproduced by an exponential function with best-fit decay constants in the range of 20-40 days. A sudden discontinuity in the evolution of released postseismic moment at ≈130 days after the main shock does not correlate with independent seismological and geodetic data and is attributed to residual noise in the InSAR time series. The data are unable to resolve migration of afterslip along the fault probably because of the time interval (six days) between the main shock and the first radar acquisition. Surface fractures observed along the Paganica fault follow the steepest gradients of postseismic line-of-sight satellite displacements and are consistent with a sudden and delayed failure of the shallow layer in response to upward tapering of slip. The occurrence of afterslip at various levels through the entire seismogenic layer argues against exclusive depth-dependent variations of frictional properties on the fault, supporting the hypothesis of significant horizontal frictional heterogeneities and/or geometrical complexities. We support the hypothesis that such heterogeneities and complexities may be at the origin of the long-term variable behavior suggested by the paleoseismological studies. Rupture of fault patches with dimensions similar to that activated in 2009 appears to have a ≈500 year recurrence time interval documented by paleoseismic and historical studies. In addition to that

  3. Short time transient periodicities from Cyg X-1

    NASA Technical Reports Server (NTRS)

    Auriemma, G.; Cardini, D.; Costa, E.; Giovannelli, F.; Ranieri, M.

    1976-01-01

    The temporal behavior of three new events of modulated optical emission from Cyg X1, detected in July 1975, is presented. Short time periodicities in the optical band are investigated. Single photon pulses from the photomultiplier are recorded on magnetic tape together with a very accurate 1 kHz reference frequency. During playback of the tape, the reference signal gives a 1 ms timing to a scaler interfaced with a small processor and the number of photon per millisecond is recorded on a digital tape.

  4. Pilot Joe Walker with the X-1E

    NASA Technical Reports Server (NTRS)

    1958-01-01

    A photo of the nose section of the X-1E with pilot Joe Walker suited for a flight at the NASA High-Speed Flight Station, Edwards, California. The dice and Little Joe are prominently displayed under the cockpit area. NASA employees and the crew chief of the plane worked long hours preparing a craft for flight. A break from the tedious task was a welcome reprieve at times; hence the private joke between a crew and their pilot evolved. If you know the craps game you've figured it out! (Little Joe is a dice player's slang term for two deuces.)

  5. Scorpius X-1: Energy Transfer from the Core to the Radio Lobes

    NASA Astrophysics Data System (ADS)

    Fomalont, E. B.; Geldzahler, B. J.; Bradshaw, C. F.

    2001-05-01

    The evolution of the radio emission from Scorpius X-1 is determined from a 56 hr continuous VLBI observation and from shorter observations over a 4 yr period. The radio source consists of a variable core near the binary and two variable compact radio lobes, which form near the core, move diametrically outward, and then fade away. Subsequently, a new lobe pair form near the core and the behavior repeats. The differences in the radio properties of the two lobes are consistent with the delay and Doppler boosting associated with an average space velocity of 0.45c at 44° to the line of sight. Four lobe speeds, between 0.32c and 0.57c, were measured for several lobe pairs on different days. The speed during each epoch remained constant over many hours. The direction of motion of the lobes over all epochs remained constant to a few degrees. Two core flares are contemporaneous with two lobe flares after removal of the delay associated with an energy burst moving with speed βj>0.95 in a twin beam from the core to each lobe. This is the first direct measurement of the speed of energy flow within an astrophysical jet. The similarity of the core and lobe flares suggests that the twin-beam flow is symmetric and that the core is located near the base of the beam.

  6. Simultaneous Hubble Space Telescope/Rossi X-Ray Timing Explorer Observations of Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Kallman, T.; Boroson, B.; Vrtilek, S. D.

    1998-07-01

    Scorpius X-1 is the brightest extrasolar point source of X-rays and may serve as a prototype for low-mass X-ray binaries as a class. It has been suggested that the UV and optical emission arise as a result of reprocessing of X-rays and that a likely site for such reprocessing is an accretion disk around the X-ray source. If UV and optical emission are enhanced by the reprocessing of X-rays, the X-ray variability may be manifest in UV emission. We test this by using high temporal resolution UV data obtained simultaneously with high temporal resolution X-ray data collected by the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope and by the X-Ray Timing Explorer. We analyze the variability behavior of the UV spectrum and of the X-rays, and we also measure the properties of the emission-line profiles as viewed at high resolution (resolving power ~= 25,000) with the echelle gratings. The variability behavior does not provide direct support for the reprocessing scenario, although the correlated variability between UV and X-rays does not conflict with this hypothesis. Furthermore, the emission-line profiles do not fit with simple models for disk emission lines.

  7. On possible photometric manifestation of magnetic field in Cyg X-1

    NASA Astrophysics Data System (ADS)

    Karitskaya, E. A.; Bochkarev, N. G.

    2015-02-01

    We consider the influence of the magnetic field of the O9.7 Iab supergiant component in the Cyg X-1 X-ray binary system on its atmosphere. In the frame of the simplest model (the unipolar cylindrically symmetric circum-polar magnetic spot model in static approximation, neglecting the Lorentz force component related to the force line curvature), the magnetic pressure is found to be comparable to model-atmosphere gas and radiative pressure, exceeding them in the area around the magnetic poles. As a result, bright spots are formed on the star surface. The dipolar or quadrupolar magnetic field can create large-size bright spots which can be studied by ground-based optical photometry. In the case of magnetic field inclined to the stellar rotation axis, resulting variability may be of the order of 1%. The field of higher multipolar configuration (produced by dynamo) can form smaller spots and may be detected only by space telescopes. Besides, the spots may be revealed from spectral-line profile variability. Observations of spots can be used as an instrument of magnetic field analysis.

  8. Spectroscopy of the Stellar Wind in the Cygnus X-1 System

    NASA Technical Reports Server (NTRS)

    Miskovicova, Ivica; Hanke, Manfred; Wilms, Joern; Nowak, Michael A.; Pottschmidt, Katja; Schultz, Norbert

    2010-01-01

    The X-ray luminosity of black holes is produced through the accretion of material from their companion stars. Depending on the mass of the donor star, accretion of the material falling onto the black hole through the inner Lagrange point of the system or accretion by the strong stellar wind can occur. Cygnus X-1 is a high mass X-ray binary system, where the black hole is powered by accretion of the stellar wind of its supergiant companion star HDE226868. As the companion is close to filling its Roche lobe, the wind is not symmetric, but strongly focused towards the black hole. Chandra-HETGS observations allow for an investigation of this focused stellar wind, which is essential to understand the physics of the accretion flow. We compare observations at the distinct orbital phases of 0.0, 0.2, 0.5 and 0.75. These correspond to different lines of sights towards the source, allowing us to probe the structure and the dynamics of the wind.

  9. Characterization of Earthquake-Induced Ground Motion from the L'Aquila Seismic Sequence of 2009, Italy

    NASA Astrophysics Data System (ADS)

    Malagnini, L.; Akinci, A.; Mayeda, K. M.; Munafo', I.; Herrmann, R. B.; Mercuri, A.

    2010-12-01

    Based only on weak-motion data, we carried out a combined study on region-specific source scaling and crustal attenuation in the Central Apennines (Italy). Our goal was to obtain a reappraisal of the existing predictive relationships for the ground motion, and to test them against the strong-motion data (Peak Ground Acceleration, PGA, Peak Ground Velocity, PGV, and Spectral Acceleration, SA) gathered during the Mw 6.15 L’Aquila earthquake (April 6, 2009, 01:32 UTC). The L’Aquila main-shock was not part of the predictive study, and the validation test was an extrapolation to one magnitude unit above the largest earthquake of the calibration data set. The regional attenuation was determined through a set of regressions on a data set of 12,777 high-quality, high-gain waveforms with excellent S/N ratios (4,259 vertical, and 8,518 horizontal time histories). Seismograms were selected from the recordings of 170 fore-shocks and after-shocks of the sequence (the complete set of all earthquakes with ML ≥ 3.0, from October 1, 2008, to May 10, 2010). All waveforms were downloaded from the ISIDe web page (http://iside.rm.ingv.it/iside/standard/index.jsp), a web site maintained by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). Weak-motion data were used to obtain a moment tensor solution, as well as a coda-based moment-rate source spectrum, for each one of the 170 events of the L’Aquila sequence (2.8 ≤ Mw ≤ 6.15). Source spectra were used to verify the good agreement with the source scaling of the Colfiorito seismic sequence of 1997-98 recently described by Malagnini et al. (2008). Finally, results on source excitation and crustal attenuation were used to produce the absolute site terms for the 23 stations located within ~ 80 km of the epicentral area. The complete set of spectral corrections (crustal attenuation and absolute site effects) was used to implement a fast and accurate tool for the automatic computation of moment magnitudes in the Central

  10. The connection between prestellar cores and filaments in cluster-forming clumps of the Aquila Rift complex

    NASA Astrophysics Data System (ADS)

    Könyves, Vera; André, Philippe; Maury, Anaëlle

    2015-08-01

    One of the main goals of the Herschel Gould Belt survey (André et al. 2010) is to elucidate the physicalmechanisms responsible for the formation and evolution of prestellar cores in molecular clouds. In theAquila cloud complex imaged with Herschel/SPIRE-PACS between 70-500 μm, we have recently identifieda complete sample of 651 starless cores, 446 of them are gravitationally-bound prestellar cores, likelyforming stars in the future. We also detected 58 protostellar cores (Könyves et al. 2010 and 2015, subm.- see http://gouldbelt-herschel.cea.fr/archives). This region is dominated by two (proto)clusters which arecurrently active sites of clustered star formation (SF): the filamentary Serpens South cloud and the W40HII region. The latter is powered by massive young stars, and a 2nd-generation SF can be witnessed inthe surroundings (Maury et al. 2011).Our Herschel observations also provide an unprecedented census of filaments in Aquila and suggest aclose connection between them and the formation process of prestellar cores, where both structures arehighly concentrated around the protoclusters. About 10-20% of the gas mass is in the form of filamentsbelow Av~7, while ~50-75% of the dense gas mass above Av~7-10 is in filamentary structures.Furthermore, ~90% of our prestellar cores are located above a background column density correspondingto Av~7, and ~75% of them lie within the densest filamentary structures with supercritical masses per unitlength >16 M⊙/pc. Indeed, a strong correlation is found between the spatial distribution of prestellar coresand the densest filaments.Comparing the statistics of cores and filaments with the number of young stellar objects found by Spitzerin the same complex, we also infer a typical timescale ~1 Myr for the formation and evolution of bothprestellar cores and filaments.In summary, our Herschel findings in Aquila support a filamentary paradigm for the early stages of SF,where the cores result from the gravitational fragmentation

  11. Broad-Band Spectroscopy of Hercules X-1 with Suzaku

    NASA Technical Reports Server (NTRS)

    Asami, Fumi; Enoto, Teruaki; Iwakiri, Wataru; Yamada, Shin'ya; Tamagawa, Toru; Mihara, Tatehiro; Nagase, Fumiaki

    2014-01-01

    Hercules X-1 was observed with Suzaku in the main-on state from 2005 to 2010. The 0.4- 100 keV wide-band spectra obtained in four observations showed a broad hump around 4-9 keV in addition to narrow Fe lines at 6.4 and 6.7 keV. The hump was seen in all the four observations regardless of the selection of the continuum models. Thus it is considered a stable and intrinsic spectral feature in Her X-1. The broad hump lacked a sharp structure like an absorption edge. Thus it was represented by two different spectral models: an ionized partial covering or an additional broad line at 6.5 keV. The former required a persistently existing ionized absorber, whose origin was unclear. In the latter case, the Gaussian fitting of the 6.5-keV line needs a large width of sigma = 1.0-1.5 keV and a large equivalent width of 400-900 eV. If the broad line originates from Fe fluorescence of accreting matter, its large width may be explained by the Doppler broadening in the accretion flow. However, the large equivalent width may be inconsistent with a simple accretion geometry.

  12. The Variable Superorbital Modulation of Cygnus X-1

    NASA Astrophysics Data System (ADS)

    Rico, Javier

    2008-08-01

    We study the superorbital modulation present in the Cygnus X-1 X-ray data, usually attributed to the precession of the accretion disk and relativistic jets. We find a new, strong, 326 ± 2 day period modulation starting in 2005, in Swift BAT and RXTE ASM light curves (LCs). We also investigate Vela 5B ASM and Ariel 5 ASM archival data and confirm the previously reported ~290 day periodic modulation, therefore confirming that the superorbital period is not constant. Finally, we study RXTE ASM LC before 2005 and find that the previously reported ~150 day period is most likely an artifact due to the use of a Fourier-power-based analysis under the assumption that the modulation has a constant period along the whole data sample. Instead, we find strong indications of several discrete changes of the precession period, happening in coincidence with soft and failed state transition episodes. We also find a hint of correlation between the period and the amplitude of the modulation. The detection of gamma rays above 100 GeV with MAGIC in 2006 September happened in coincidence with a maximum of the superorbital modulation. The next maximum will happen between 2008 July 2 and 14, when the observational conditions of Cygnus X-1 with ground-based Cerenkov telescopes, such as MAGIC and VERITAS, are optimal.

  13. RXTE observation of Cygnus X-1: spectral analysis

    NASA Astrophysics Data System (ADS)

    Dove, J. B.; Wilms, Jörn; Nowak, M. A.; Vaughan, B. A.; Begelman, M. C.

    1999-01-01

    We present the results of the analysis of the broad-band spectrum of Cygnus X-1 from 3.0 to 200keV, using data from a 10ksec observation by the Rossi X-ray Timing Explorer. Although the spectrum can be well described phenomenologically by an exponentially cut-off power law (photon index Γ=1.45+0.01-0.02, e-folding energy Ef=162+9-8keV, plus a deviation from a power law that formally can be modeled as a thermal blackbody with temperature kTBB=1.2+0.0-0.1keV), the inclusion of a reflection component does not improve the fit. As a physical description of this system, we apply the accretion disc corona (ADC0 models of Dove, Wilms & Begelman [1]). A slab-geometry ADC model is unable to describe the data. However, a spherical corona, with a total optical depth τ=1.6+/-0.1 and an average temperature kTC=87+/-5keV, surrounded by an exterior cold disc, does provide a good description of the data (χ2red=1.55). These models deviate from the data by up to 7% in the 5-10keV range. However, considering how successfully the spherical corona reproduces the 10-200keV data, such ``photon-starved'' coronal geometries seem very promising for explaining the accretion processes of Cygnus X-1.

  14. Circinus X-1 - X-ray observations with SAS 3

    NASA Technical Reports Server (NTRS)

    Dower, R. G.; Bradt, H. V.; Morgan, E. H.

    1982-01-01

    Eight observations of Cir X-1 with SAS 3, each lasting 1-6 days, have yielded a variety of new phenomena, viz., a luminous state of steady emission, rapid large-intensity dips, an extremely rapid X-ray transition, and bright flares. Through searches for periodic X-ray pulsations were carried out on data trains of duration up to 6 days; upper limits for pulsations with periods greater than 250 microsec range down to 0.3%. Aperiodic variability with characteristic times of 0.4-1.0 sec was observed but is not well characterized by a simple shot noise model. No millisecond bursts were observed during 40,000 sec in three separate observations. Spectral parameters derived before and after several X-ray transitions indicate that the transitions are not due to absorption of X-rays by intervening gas. Models previously proposed for the Cir X-1 system do not easily provide explanations for all the complex phenomena reported herein.

  15. The showerfront time-structure of anomalous muon'' events associated with Hercules X-1. [Her X-1

    SciTech Connect

    Alexandreas, D.E. ); Berley, D.; Biller, S.D.; Burman, R.L.; Cady, D.R.; Chang, C.Y.; Dingus, B.L.; Dion, C.; Dion, G.M.; Ellsworth, R.W.; Goodman, J.A.; Haines, T.J.; Hoffman, C.M.; Krakauer, D.A.; Kwok, P.W.; Lloyd-Evans, J.; Lu, X.; Nagle, D.E.; Potter, M.E.; Sandberg, V.D.; Stark, M.J.; Vishwanath, P.R.; Yodh, G.B.; Zhang, W.P. The University of Maryland, College Park, Maryland 20742-4111 Los Alamos National Laboratory, Los Alamos, New Mexico 87545 The University of Notre Dame, Notre Dame, Indiana 46556 George Mason University, Fairfax, Virginia 22030-4444 Argonne National Laboratory, Argonne, Illinois, 60439-4843 ); Presented by S. Biller

    1991-04-05

    The 11 in-phase'' source events from the 1986 muon-rich bursts associated with Hercules X-1 (previously reported by this group) have been studied for indications of further anomalous behavior. The most significant effect observed resulted from an analysis of the showerfront time-structures of these events. This analysis was then applied {ital a} {ital priori} to the rest of the source day, where an additional {similar to}9 signal events are expected to remain. The same effect was observed at a chance probability level of {similar to}0.1%.

  16. A fluorescent approach for identifying P2X1 ligands

    PubMed Central

    Ruepp, Marc-David; Brozik, James A.; de Esch, Iwan J.P.; Farndale, Richard W.; Murrell-Lagnado, Ruth D.; Thompson, Andrew J.

    2015-01-01

    There are no commercially available, small, receptor-specific P2X1 ligands. There are several synthetic derivatives of the natural agonist ATP and some structurally-complex antagonists including compounds such as PPADS, NTP-ATP, suramin and its derivatives (e.g. NF279, NF449). NF449 is the most potent and selective ligand, but potencies of many others are not particularly high and they can also act at other P2X, P2Y and non-purinergic receptors. While there is clearly scope for further work on P2X1 receptor pharmacology, screening can be difficult owing to rapid receptor desensitisation. To reduce desensitisation substitutions can be made within the N-terminus of the P2X1 receptor, but these could also affect ligand properties. An alternative is the use of fluorescent voltage-sensitive dyes that respond to membrane potential changes resulting from channel opening. Here we utilised this approach in conjunction with fragment-based drug-discovery. Using a single concentration (300 μM) we identified 46 novel leads from a library of 1443 fragments (hit rate = 3.2%). These hits were independently validated by measuring concentration-dependence with the same voltage-sensitive dye, and by visualising the competition of hits with an Alexa-647-ATP fluorophore using confocal microscopy; confocal yielded kon (1.142 × 106 M−1 s−1) and koff (0.136 s−1) for Alexa-647-ATP (Kd = 119 nM). The identified hit fragments had promising structural diversity. In summary, the measurement of functional responses using voltage-sensitive dyes was flexible and cost-effective because labelled competitors were not needed, effects were independent of a specific binding site, and both agonist and antagonist actions were probed in a single assay. The method is widely applicable and could be applied to all P2X family members, as well as other voltage-gated and ligand-gated ion channels. This article is part of the Special Issue entitled ‘Fluorescent Tools in Neuropharmacology

  17. The self-built ecovillage in L'Aquila, Italy: community resilience as a grassroots response to environmental shock.

    PubMed

    Fois, Francesca; Forino, Giuseppe

    2014-10-01

    The paper applies the community resilience approach to the post-disaster case of Pescomaggiore, an Italian village affected by the L'Aquila earthquake in 2009. A group of residents refused to accept the housing recovery solutions proposed by the government, opting for autonomous recovery. They developed a housing project in the form of a self-built ecovillage, characterised by earthquake-proof buildings made of straw and wood. The project is a paradigmatic example of a community-based response to an external shock. It illustrates the concept of 'community resilience', which is widely explored in the scientific debate but still vaguely defined. Based on qualitative methodologies, the paper seeks to understand how the community resilience process can be enacted in alternative social practices such as ecovillages. The goal is to see under which conditions natural disasters can be considered windows of opportunity for sustainability. PMID:25196333

  18. On the torque reversal occurred in X-ray binaries

    NASA Astrophysics Data System (ADS)

    Gong, Biping

    The effect of torque reversal has been observed in a number of X-ray binaries, such as 4U1627-67, Her X-1, Cen X-3, GX 1+4, OAO 1657-415, and Vela X-1. Here we suggest that it originates in a simply mechanism, residual Doppler shift. In a binary system with periodic signals sending to an observer, the drift of the signal frequency actually changes with the varying orbital velocity, projected to line of sight at different phases of orbit. And it has been taken for granted that the net red-shift and blue-shift of an full orbit circle be cancelled out, so that the effect of Doppler shift to the signal in binary motion cannot be accumulated over the orbital period. However, taking the propagation time at each velocity state into account, the symmetry of the velocity distribution over the orbital phase is broken. Consequently, the net Doppler shift left in an orbit is non-zero. It is this Newtonian second Doppler effect that responsible for the torque reversal occurred in X-ray binaries.

  19. Aerosol Measurements in the Atmospheric Surface Layer at L'Aquila, Italy: Focus on Biogenic Primary Particles

    NASA Astrophysics Data System (ADS)

    Pitari, Giovanni; Coppari, Eleonora; De Luca, Natalia; Di Carlo, Piero; Pace, Loretta

    2014-09-01

    Two year measurements of aerosol concentration and size distribution (0.25 μm < d < 30 μm) in the atmospheric surface layer, collected in L'Aquila (Italy) with an optical particle counter, are reported and analysed for the different modes of the particle size distribution. A different seasonal behaviour is shown for fine mode aerosols (largely produced by anthropogenic combustion), coarse mode and large-sized aerosols, whose abundance is regulated not only by anthropogenic local production, but also by remote natural sources (via large scale atmospheric transport) and by local sources of primary biogenic aerosols. The observed total abundance of large particles with diameter larger than 10 μm is compared with a statistical counting of primary biogenic particles, made with an independent technique. Results of these two observational approaches are analysed and compared to each other, with the help of a box model driven by observed meteorological parameters and validated with measurements of fine and coarse mode aerosols and of an atmospheric primary pollutant of anthropogenic origin (NOx). Except in winter months, primary biogenic particles in the L'Aquila measurement site are shown to dominate the atmospheric boundary layer population of large aerosol particles with diameter larger than 10 μm (about 80 % of the total during summer months), with a pronounced seasonal cycle, contrary to fine mode aerosols of anthropogenic origin. In order to explain these findings, the main mechanisms controlling the abundance and variability of particulate matter tracers in the atmospheric surface layer are analysed with the numerical box-model.

  20. Bifurcation timescales in power spectra of black hole binaries and ultraluminous X-ray sources

    NASA Astrophysics Data System (ADS)

    Wang, Taishan; Li, Tipei

    2010-01-01

    For black hole binaries (BHBs) and active galactic nuclei (AGNs), bifurcation timescales (BTs) Δ t b exist, below which time-domain power is significantly higher than the corresponding Fourier power. Quasi-periodic oscillations (QPOs) are removed from the Fourier spectra of BHBs. A relationship between BT, black hole mass and bolometric luminosity is derived. Strong anti-correlation between BT and luminosity of Cyg X-1 is found. After removing the QPOs, BTs are also obtained for two ultraluminous X-ray sources (ULXs), M82 X-1 and NGC5408 X-1. The results support that they harbor intermediate mass black holes (IMBHs).

  1. Binary synchronous simulator

    NASA Technical Reports Server (NTRS)

    Rogers, J. R., III

    1980-01-01

    Flexible simulator for trouble-shooting data transmission system uses binary synchronous communications protocol to produce error-free transmission of data between two points. Protocol may be used to replace display generator or be directly fed to display generator.

  2. Double Degenerate Binary Systems

    SciTech Connect

    Yakut, K.

    2011-09-21

    In this study, angular momentum loss via gravitational radiation in double degenerate binary (DDB)systems (NS + NS, NS + WD, WD + WD, and AM CVn) is studied. Energy loss by gravitational waves has been estimated for each type of systems.

  3. Binary pattern deflectometry.

    PubMed

    Butel, Guillaume P; Smith, Greg A; Burge, James H

    2014-02-10

    Deflectometry is widely used to accurately calculate the slopes of any specular reflective surface, ranging from car bodies to nanometer-level mirrors. This paper presents a new deflectometry technique using binary patterns of increasing frequency to retrieve the surface slopes. Binary Pattern Deflectometry allows almost instant, simple, and accurate slope retrieval, which is required for applications using mobile devices. The paper details the theory of this deflectometry method and the challenges of its implementation. Furthermore, the binary pattern method can also be combined with a classic phase-shifting method to eliminate the need of a complex unwrapping algorithm and retrieve the absolute phase, especially in cases like segmented optics, where spatial algorithms have difficulties. Finally, whether it is used as a stand-alone or combined with phase-shifting, the binary patterns can, within seconds, calculate the slopes of any specular reflective surface. PMID:24663273

  4. Gamma-ray observations of Cygnus X-1

    NASA Astrophysics Data System (ADS)

    Bassani, L.; Di Cocco, G.; Stephen, J. B.; Dean, A. J.; Perotti, F.

    1989-08-01

    The results of gamma-ray observations of the Galactic black hole candidate Cygnus X-1 are presented. The recent HEAO 3 results reported by Ling et al. (1987) on this source are confirmed: (1) the detection in 1979 of a gamma-ray excess of comparable flux; and (2) a spectral variation above about 25 keV going from 1979 to 1980, which implies and anticorrelation between hard X-ray and gamma-ray luminosities with a pivot point in the 200-400 keV band. A comparison of all the data available at gamma-ray energies gives further support to the existence of this anticorrelation, although its statistical significance is low. The hard X-ray/gamma-ray 1979 spectrum, which is well fitted by a power law with photon index alpha = 1.7, can be interpreted as thermal Comptonization of soft photons or in terms of nonthermal models with copious photon-photon absorption.

  5. Understanding accretion beyond the Eddington limit: NGC 5204 X-1

    NASA Astrophysics Data System (ADS)

    Sutton, Andrew

    2013-10-01

    It has been suggested that ULXs are in a new super-Eddington `ultraluminous' accretion state, and that they progress through a sequence of three spectral regimes with increasing accretion rate. However, our recent results (Sutton et al. 2013) indicate that inclination is also critical in determining the observed X-ray properties. These properties can broadly be explained by a massive radiatively-driven wind that emerges as the Eddington limit is exceeded, and forms a funnel around the black hole axis. Previous observations show NGC 5204 X-1 straddling the boundary between two ultraluminous regimes, marking it as a critical source in testing this scenario. Here we propose to obtain a further four 20 ks XMM-Newton EPIC observations, which will allow us to probe the validity of the proposed model.

  6. TIMESCALE-RESOLVED SPECTROSCOPY OF Cyg X-1

    SciTech Connect

    Wu, Y. X.; Li, T. P.; Belloni, T. M.; Wang, T. S.; Liu, H.

    2009-04-20

    We propose the timescale-resolved spectroscopy (TRS) as a new method to combine the timing and spectral study. The TRS is based on the time domain power spectrum and reflects the variable amplitudes of spectral components on different timescales. We produce the TRS with the RXTE PCA data for Cyg X-1 and study the spectral parameters (the power-law photon index and the equivalent width of the iron fluorescent line) as a function of timescale. The results of TRS and frequency-resolved spectra have been compared, and similarities have been found for the two methods with the identical motivations. We also discover the correspondences between the evolution of photon index with timescale and the evolution of the equivalent width with timescale. The observations can be divided into three types according to the correspondences and different type is connected with different spectral state.

  7. Joe Walker in pressure suit with X-1E

    NASA Technical Reports Server (NTRS)

    1958-01-01

    Joe Walker in a pressure suit beside the X-1E at the NASA High-Speed Flight Station, Edwards,California. The dice and 'Little Joe' are prominently displayed under the cockpit area. (Little Joe is a dice players slang term for two deuces.) Walker is shown in the photo wearing an early Air Force partial pressure suit. This protected the pilot if cockpit pressure was lost above 50,000 feet. Similar suits were used in such aircraft as B-47s, B-52s, F-104s, U-2s, and the X-2 and D-558-II research aircraft. Five years later, Walker reached 354,200 feet in the X-15. Similar artwork - reading 'Little Joe the II' - was applied for the record flight. These cases are two of the few times that research aircraft carried such nose art.

  8. The Extreme Spin of the Black Hole Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Gou, Lijun; McClintock, Jeffrey E.; Reid, Mark J.; Orosz, Jerome A.; Steiner, James F.; Narayan, Ramesh; Xiang, Jingen; Remillard, Ronald A.; Arnaud, Keith A.; Davis, Shane W.

    2011-01-01

    Remarkably, an astronomical black hole is completely described by the two numbers that specify its mass and its spin. Knowledge of spin is crucial for understanding how, for example, black holes produce relativistic jets. Recently, it has become possible to measure the spins of black holes by focusing on the very inner region of an accreting disk of hot gas orbiting the black hole. According to General Relativity (GR), this disk is truncated at an inner radius 1 that depends only on the mass and spin of the black hole. We measure the radius of the inner edge of this disk by fitting its continuum X-ray spectrum to a fully relativistic model. Using our measurement of this radius, we deduce that the spin of Cygnus X-1 exceeds 97% of the maximum value allowed by GR.

  9. RXTE Observation of Cygnus X-1. Report 2; TIming Analysis

    NASA Technical Reports Server (NTRS)

    Nowak, Michael A.; Vaughan, Brian A.; Wilms, Joern; Dove, James B.; Begelman, Mitchell C.

    1998-01-01

    We present timing analysis for a Rossi X-ray Timing Explorer (RXTE) observation of Cygnus X-1 in its hard/low state. This was the first RXTE observation of Cyg X-1 taken after it transited back to this state from its soft/high state. RXTE's large effective area, superior timing capabilities, and ability to obtain long, uninterrupted observations have allowed us to obtain measurements of the power spectral density (PSD), coherence function, and Fourier time lags to a decade lower in frequency and half a decade higher in frequency than typically was achieved with previous instruments. Notable aspects of our observations include a weak 0.005 Hz feature in the PSD coincident with a coherence recovery; a 'hardening' of the high-frequency PSD with increasing energy; a broad frequency range measurement of the coherence function, revealing rollovers from unity coherence at both low and high frequency; and an accurate determination of the Fourier time lags over two and a half decades in frequency. As has been noted in previous similar observations, the time delay is approximately proportional to f(exp -0.7), and at a fixed Fourier frequency the time delay of the hard X-rays compared to the softest energy channel tends to increase logarithmically with energy. Curiously, the 0.01-0.2 Hz coherence between the highest and lowest energy bands is actually slightly greater than the coherence between the second highest and lowest energy bands. We carefully describe all of the analysis techniques used in this paper, and we make comparisons of the data to general theoretical expectations. In a companion paper, we make specific comparisons to a Compton corona model that we have successfully used to describe the energy spectral data from this observation.

  10. RXTE Observation of Cygnus X-1 Spectral Analysis

    NASA Technical Reports Server (NTRS)

    Dove, J. B.; Wilms, Joern; Nowak, M. A.; Vaughan, B. A.; Begelman, M. C.

    1998-01-01

    We present the results of the analysis of the broad-band spectrum of Cygnus X-1 from 3.0 to 200 keV, using data from a 10 ksec observation by the Rossi X-ray Timing Explorer. Although the spectrum can be well described phenomenologically by an exponentially cut-off power law (photon index Gamma = 1.45+0.01 -0.02 , e-folding energy e(sub f) = 162+9 -8 keV, plus a deviation from a power law that formally can be modeled as a thermal blackbody, with temperature kT(sub BB) = 1.2 +0.0 -0.1 keV), the inclusion of a reflection component does not improve the fit. As a physical description of this system, we apply the accretion disc corona (ADC) models. A slab-geometry ADC model is unable to describe the data. However, a spherical corona, with a total optical depth tau- = 1.6 + or - 0.1 and an average temperature kTc = 87 + or - 5 keV, surrounded by an exterior cold disc, does provide a good description of the data (X red (exp 2) = 1.55). These models deviate from the data bv up to 7% in the 5-10 keV range. However, considering how successfully the spherical corona reproduces the 10-200 keV data, such "photon-starved" coronal geometries seem very promising for explaining the accretion processes of Cygnus X-1.

  11. RXTE observation of Cygnus X-1 - I. Spectral analysis

    NASA Astrophysics Data System (ADS)

    Dove, James B.; Wilms, Jörn; Nowak, Michael A.; Vaughan, Brian A.; Begelman, Mitchell C.

    1998-08-01

    We present the results of the analysis of the broad-band spectrum of Cygnus X-1 from 3.0 to 200keV, using data from a 10-ks observation by the Rossi X-ray Timing Explorer (RXTE). The spectrum can be well described phenomenologically by an exponentially cut-off power law with a photon index Γ=1.45+0.01-0.02 (a value considerably harder than is typically found), e-folding energy Ef=162+9-8keV, plus a deviation from a power law that formally can be modelled as a thermal blackbody with temperature kTbb=1.2+0.0-0.1keV. Although the 3-30 keV portion of the spectrum can be fitted with a reflected power law with Γ=1.81+/-0.01 and covering fraction f=0.35+/-0.02, the quality of the fit is significantly reduced when the HEXTE data in the 30-100 keV range are included, as there is no observed softening in the power law within this energy range. As a physical description of this system, we apply the accretion disc corona models of Dove, Wilms &38 Begelman, in which the temperature of the corona is determined self-consistently. A spherical corona with a total optical depth τ=1.6+/-0.1 and an average temperature kTc=87+/-5keV, surrounded by an exterior cold disc, does provide a good description of the data (χ2red=1.55). These models deviate from the data by up to 7 per cent in the 5-10keV range, and we discuss possible reasons for these discrepancies. However, considering how successfully the spherical corona reproduces the 10-200keV data, such `photon-starved' coronal geometries seem very promising for explaining the accretion processes of Cygnus X-1.

  12. VELA X-1: how to produce asymmetric eclipses.

    NASA Astrophysics Data System (ADS)

    Feldmeier, A.; Anzer, U.; Boerner, G.; Nagase, F.

    1996-07-01

    Light curves of the X-ray pulsar Vela X-1 obtained with the ASCA satellite show a strong asymmetry in the hard energy band during the eclipse of the X-ray source: a steep drop at ingress is followed by a gradual decline, whereas only a steep increase is observed at egress. X-ray scattering off the dense accretion wake trailing the neutron star cannot explain the gradual decline because of the long persistence of the latter ({DELTA}φ=0.11). Instead we propose that scattering in an extended photoionization wake is responsible. This wake is caused by the switch-off of the radiative force that drives the B supergiant wind during the passage through the highly ionized Stroemgren region surrounding the X-ray source. The stalled gas then trails the neutron star, which moves relative to the B star surface (no corotation). A model for the Vela X-1 system which assumes that the B star does not rotate gives too large a phase extent for the dense wake and can be ruled out. Including the B star rotation in an approximate way, the relative azimuthal motion of the neutron star is slower and the wake covers a smaller phase interval. Finally, we assume that the Stroemgren sphere does not reach too deep into the wind accelerating region. The wind can then reach a certain fraction of the terminal velocity before the radiative force is switched off. This elongates the photoionization wake further and both its phase extent and its scattering efficiency match the observations.

  13. Spectroscopic Binary Stars

    NASA Astrophysics Data System (ADS)

    Batten, A.; Murdin, P.

    2000-11-01

    Historically, spectroscopic binary stars were binary systems whose nature was discovered by the changing DOPPLER EFFECT or shift of the spectral lines of one or both of the component stars. The observed Doppler shift is a combination of that produced by the constant RADIAL VELOCITY (i.e. line-of-sight velocity) of the center of mass of the whole system, and the variable shift resulting from the o...

  14. Binary-Symmetry Detection

    NASA Technical Reports Server (NTRS)

    Lopez, Hiram

    1987-01-01

    Transmission errors for zeros and ones tabulated separately. Binary-symmetry detector employs psuedo-random data pattern used as test message coming through channel. Message then modulo-2 added to locally generated and synchronized version of test data pattern in same manner found in manufactured test sets of today. Binary symmetrical channel shows nearly 50-percent ones to 50-percent zeroes correspondence. Degree of asymmetry represents imbalances due to either modulation, transmission, or demodulation processes of system when perturbed by noise.

  15. HZ Her/Her X-1: Study of the light curve dips

    NASA Astrophysics Data System (ADS)

    Igna, Ciprian Dacian

    The HZ Her/Her X-1 X-ray binary exhibits rapid and variable X-ray absorption features. These were noticed soon after the discovery of its periodic flux variations, such as X-ray pulsations and eclipses, and were named light curve dips by Giacconi et al. 1973. Their properties were analyzed, debated and documented ever since. The largest existing set of detailed observations of Her X-1 are contained in the data archive of NASA's Rossi X-ray Timing Explorer (RXTE)/Proportional Counter Array (PCA). From this entire light curve, several hundred new light curve dips were documented, based on X-ray Softness Ratio (SR), making this thesis the most extensive study of HZ Her/Her X-1's dips to date. The dips were classified into 12 different categories in order to study their statistical distribution, intensity, duration, symmetry and SR evolution. Some dips properties depend on Her X-1's 35-day X-ray cycle, which is caused by the precessing disk around the neutron star. The 35-day phase of dips was determined using Turn-On (TO) times calculated from the February 1996 - December 2009 RXTE/All Sky Monitor (ASM) light curve. 147 TOs were found by cross-correlation with X-ray cycle templates, and the 22 Burst and Transient Source Experiment TOs were confirmed. Thus this study also has the longest time period yet for the analysis of the 35-day X-ray cycle. The set of 147 TOs does not correlate with 0.2 or 0.7 orbital phases, disproving the reports over the past 30 years. The ASM-based 35-day cycle lengths range from 33.2 to 36.7 days, with an average of 34.7 +/- 0.2 days. The observed timing of dips is illustrated in the 35-day phase vs. orbital phase plot, and compared to models. The current large set of dips gives much better detail than that of Crosa & Boynton 1980. A model for dips is developed here, which takes dips to be caused by blockage of the line of sight to the neutron star by the site of the accretion stream - disk collision. An extensive investigation of the model

  16. The quasi-periodic oscillations and very low frequency noise of Scorpius X-1 as transient chaos - A dripping handrail?

    NASA Technical Reports Server (NTRS)

    Scargle, Jeffrey D.; Steiman-Cameron, Thomas; Young, Karl; Donoho, David L.; Crutchfield, James P.; Imamura, James

    1993-01-01

    We present evidence that the quasi-periodic oscillations (QPO) and very low frequency noise (VLFN) characteristic of many accretion sources are different aspects of the same physical process. We analyzed a long, high time resolution EXOSAT observation of the low-mass X-ray binary (LMXB) Sco X-1. The X-ray luminosity varies stochastically on time scales from milliseconds to hours. The nature of this variability - as quantified with both power spectrum analysis and a new wavelet technique, the scalegram - agrees well with the dripping handrail accretion model, a simple dynamical system which exhibits transient chaos. In this model both the QPO and VLFN are produced by radiation from blobs with a wide size distribution, resulting from accretion and subsequent diffusion of hot gas, the density of which is limited by an unspecified instability to lie below a threshold.

  17. Protic ionic liquids based on the dimeric and oligomeric anions: [(AcO)xH(x-1)]-.

    PubMed

    Johansson, K M; Izgorodina, E I; Forsyth, M; MacFarlane, D R; Seddon, K R

    2008-05-28

    We describe a fluidity and conductivity study as a function of composition in N-methylpyrrolidine-acetic acid mixtures. The simple 1 : 1 acid-base mixture appears to form an ionic liquid, but its degree of ionicity is quite low and such liquids are better thought of as poorly dissociated mixtures of acid and base. The composition consisting of 3 moles acetic acid and 1 mole N-methylpyrrolidine is shown to form the highest ionicity mixture in this binary due to the presence of oligomeric anionic species [(AcO)(x)H(x-1)](-) stabilised by hydrogen bonds. These oligomeric species, being weaker bases than the acetate anion, shift the proton transfer equilibrium towards formation of ionic species, thus generating a higher degree of ionicity than is present at the 1 : 1 composition. A Walden plot analysis, thermogravimetric behaviour and proton NMR data, as well as ab initio calculations of the oligomeric species, all support this conclusion. PMID:18473045

  18. Spectral Analysis of X-Ray Binaries

    NASA Astrophysics Data System (ADS)

    Fridriksson, Joel K.

    2011-09-01

    In this thesis, I present work from three separate research projects associated with observations of X-ray binaries. Two of those revolve around spectral characteristics of neutron star low-mass X-ray binaries (NS-LMXBs), with a particular source, XTE J1701-462, playing a central role. First, I construct and study color-color and hardness-intensity diagrams (CDs and HIDs) for a large sample of NS-LMXBs using Rossi X-ray Timing Explorer (RXTE) data spanning ~15 years. I study in particular detail three sources whose complicated CDs/HIDs are strongly affected by secular motion -- Cyg X-2, Cir X-1, and GX 13+1 -- and show that Cyg X-2 and Cir X-1 display CD/HID evolution with strong similarities to the transient Z source XTE J1701-462, which was previously shown to have evolved through all subclasses of NS-LMXBs as a result of changes in mass accretion rate. I build on the results for XTE J1701-462, Cyg X-2, and Cir X-1 and rank all the sources in the sample based only on their CD/HID morphology. I speculate that this represents a rough ranking in terms of the relative ranges in mass accretion rate experienced by the sources. Next, I use data from RXTE, Swift, Chandra, and XMM-Newton to study the transition to quiescence and the first ~1200 days of the quiescent phase of XTE J1701-462 following the end of its extraordinarily luminous 19 month outburst in 2006-2007. I find that the crust of the neutron star cooled rapidly during the first ~200 days of quiescence, after having been heated out of thermal equilibrium with the core during the outburst; the source has subsequently shown slower cooling along with sporadic low-level accretion activity. I discuss the implications of the observed cooling behavior and low-level accretion, the former of which yields information on the internal properties of the neutron star. Finally, I use multiple Chandra observations to study the X-ray source populations in the late-type galaxies NGC 6946 and NGC 4485/4490. A particular

  19. Spectral signature of atmospheric reflection in Hercules X-1/HZ Hercules during low and short high states

    NASA Astrophysics Data System (ADS)

    Abdallah, M. H.; Leahy, D. A.

    2015-11-01

    We analyse RXTE/PCA X-ray spectra of the binary X-ray pulsar Her X-1/HZ Her during short high state and one binary orbit in the preceding low state, just before short high turn-on. The spectrum is well described by two continuum components (absorbed and unabsorbed). The resulting spectral parameters are modulated with orbital phase. During low state, a significant component of the flux, and its spectrum, is consistent with X-ray reflection off the face of the companion star HZ Her. This component has a significantly harder X-ray spectrum than the rest of the flux from the Her X-1 system. A second component in low state is consistent with emission from the accretion disc corona. During short high, a third strong component is present with a softer spectrum, which is associated with the neutron star and accretion disc. Due to this direct emission from the neutron star and accretion disc, the reflected emission is less clear; however, parameters and fluxes modulations during short high state indicate its presence. In low state, the hard X-ray flux (hν > 10 keV) peaks at orbital phase φorb ≃ 0.55, which is expected from a simple model of atmospheric reflection from the companion star. The offset indicates an asymmetry in the X-ray illumination of the companion, which could be due to shadowing of the the inner face of HZ Her by the accretion disc and/or stream.

  20. Searches for periodic gravitational waves from unknown isolated sources and Scorpius X-1: Results from the second LIGO science run

    NASA Astrophysics Data System (ADS)

    Abbott, B.; Abbott, R.; Adhikari, R.; Agresti, J.; Ajith, P.; Allen, B.; Amin, R.; Anderson, S. B.; Anderson, W. G.; Arain, M.; Araya, M.; Armandula, H.; Ashley, M.; Aston, S.; Aufmuth, P.; Aulbert, C.; Babak, S.; Ballmer, S.; Bantilan, H.; Barish, B. C.; Barker, C.; Barker, D.; Barr, B.; Barriga, P.; Barton, M. A.; Bayer, K.; Belczynski, K.; Berukoff, S. J.; Betzwieser, J.; Beyersdorf, P. T.; Bhawal, B.; Bilenko, I. A.; Billingsley, G.; Biswas, R.; Black, E.; Blackburn, K.; Blackburn, L.; Blair, B.; Bland, B.; Bogenstahl, J.; Bogue, L.; Bork, R.; Boschi, V.; Bose, S.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Brinkmann, M.; Brooks, A.; Brown, D. A.; Bullington, A.; Bunkowski, A.; Buonanno, A.; Burmeister, O.; Busby, D.; Butler, W. E.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Camp, J. B.; Cannizzo, J.; Cannon, K.; Cantley, C. A.; Cao, J.; Cardenas, L.; Carter, K.; Casey, M. M.; Castaldi, G.; Cepeda, C.; Chalkey, E.; Charlton, P.; Chatterji, S.; Chelkowski, S.; Chen, Y.; Chiadini, F.; Chin, D.; Chin, E.; Chow, J.; Christensen, N.; Clark, J.; Cochrane, . P.; Cokelaer, T.; Colacino, C. N.; Coldwell, R.; Coles, M.; Conte, R.; Cook, D.; Corbitt, T.; Coward, D.; Coyne, D.; Creighton, J. D. E.; Creighton, T. D.; Croce, R. P.; Crooks, D. R. M.; Cruise, A. M.; Csatorday, P.; Cumming, A.; Cutler, C.; Dalrymple, J.; D'Ambrosio, E.; Danzmann, K.; Davies, G.; Daw, E.; Debra, D.; Degallaix, J.; Degree, M.; Delker, T.; Demma, T.; Dergachev, V.; Desai, S.; Desalvo, R.; Dhurandhar, S.; Díaz, M.; Dickson, J.; di Credico, A.; Diederichs, G.; Dietz, A.; Ding, H.; Doomes, E. E.; Drever, R. W. P.; Dumas, J.-C.; Dupuis, R. J.; Dwyer, J. G.; Ehrens, P.; Espinoza, E.; Etzel, T.; Evans, M.; Evans, T.; Fairhurst, S.; Fan, Y.; Fazi, D.; Fejer, M. M.; Finn, L. S.; Fiumara, V.; Fotopoulos, N.; Franzen, A.; Franzen, K. Y.; Freise, A.; Frey, R.; Fricke, T.; Fritschel, P.; Frolov, V. V.; Fyffe, M.; Galdi, V.; Ganezer, K. S.; Garofoli, J.; Gholami, I.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Goda, K.; Goetz, E.; Goggin, L. M.; González, G.; Gossler, S.; Grant, A.; Gras, S.; Gray, C.; Gray, M.; Greenhalgh, J.; Gretarsson, A. M.; Grosso, R.; Grote, H.; Grunewald, S.; Guenther, M.; Gustafson, R.; Hage, B.; Hammer, D.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G.; Harstad, E.; Hayler, T.; Heefner, J.; Heinzel, G.; Heng, I. S.; Heptonstall, A.; Heurs, M.; Hewitson, M.; Hild, S.; Hirose, E.; Hoak, D.; Hosken, D.; Hough, J.; Howell, E.; Hoyland, D.; Huttner, S. H.; Ingram, D.; Innerhofer, E.; Ito, M.; Itoh, Y.; Ivanov, A.; Jackrel, D.; Jennrich, O.; Johnson, B.; Johnson, W. W.; Johnston, W. R.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kasprzyk, D.; Katsavounidis, E.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Keppel, D. G.; Khalili, F. Ya.; Killow, C. J.; Kim, C.; King, P.; Kissell, J. S.; Klimenko, S.; Kokeyama, K.; Kondrashov, V.; Kopparapu, R. K.; Kozak, D.; Krishnan, B.; Kwee, P.; Lam, P. K.; Landry, M.; Lantz, B.; Lazzarini, A.; Lee, B.; Lei, M.; Leiner, J.; Leonhardt, V.; Leonor, I.; Libbrecht, K.; Libson, A.; Lindquist, P.; Lockerbie, N. A.; Logan, J.; Longo, M.; Lormand, M.; Lubiński, M.; Lück, H.; Machenschalk, B.; Macinnis, M.; Mageswaran, M.; Mailand, K.; Malec, M.; Mandic, V.; Marano, S.; Márka, S.; Markowitz, J.; Maros, E.; Martin, I.; Marx, J. N.; Mason, K.; Matone, L.; Matta, V.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McHugh, M.; McKenzie, K.; McNabb, J. W. C.; McWilliams, S.; Meier, T.; Melissinos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messaritaki, E.; Messenger, C. J.; Meyers, D.; Mikhailov, E.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Mohanty, S.; Moreno, G.; Mossavi, K.; Mowlowry, C.; Moylan, A.; Mudge, D.; Mueller, G.; Mukherjee, S.; Müller-Ebhardt, H.; Munch, J.; Murray, P.; Myers, E.; Myers, J.; Nagano, S.; Nash, T.; Newton, G.; Nishizawa, A.; Nocera, F.; Numata, K.; Nutzman, P.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pan, Y.; Papa, M. A.; Parameshwaraiah, V.; Parameswariah, C.; Patel, P.; Pedraza, M.; Penn, S.; Pierro, V.; Pinto, I. M.; Pitkin, M.; Pletsch, H.; Plissi, M. V.; Postiglione, F.; Prix, R.; Quetschke, V.; Raab, F.; Rabeling, D.; Radkins, H.; Rahkola, R.; Rainer, N.; Rakhmanov, M.; Ramsunder, M.; Rawlins, K.; Ray-Majumder, S.; Re, V.; Regimbau, T.; Rehbein, H.; Reid, S.; Reitze, D. H.; Ribichini, L.; Richman, S.; Riesen, R.; Riles, K.; Rivera, B.; Robertson, N. A.; Robinson, C.; Robison, E. L.; Roddy, S.; Rodriguez, A.; Rogan, A. M.; Rollins, J.; Romano, J. D.; Romie, J.; Rong, H.; Route, R.; Rowan, S.; Rüdiger, A.; Ruet, L.; Russell, P.; Ryan, K.; Sakata, S.; Samidi, M.; Sancho de La Jordana, L.; Sandberg, V.; Sanders, G. H.; Sannibale, V.; Saraf, S.; Sarin, P.; Sathyaprakash, B.; Sato, S.; Saulson, P. R.; Savage, R.; Savov, P.; Sazonov, A.; Schediwy, S.; Schilling, R.; Schnabel, R.; Schofield, R.; Schutz, B. F.; Schwinberg, P.; Scott, S. M.; Searle, A. C.; Sears, B.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Shawhan, P.; Shoemaker, D. H.; Sibley, A.; Sidles, J. A.; Siemens, X.; Sigg, D.; Sinha, S.; Sintes, A. M.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Somiya, K.; Strain, K. A.; Strand, N. E.; Strom, D. M.; Stuver, A.; Summerscales, T. Z.; Sun, K.-X.; Sung, M.; Sutton, P. J.; Sylvestre, J.; Takahashi, H.; Takamori, A.; Tanner, D. B.; Tarallo, M.; Taylor, R.; Taylor, R.; Thacker, J.; Thorne, K. A.; Thorne, K. S.; Thüring, A.; Tinto, M.; Tokmakov, K. V.; Torres, C.; Torrie, C.; Traylor, G.; Trias, M.; Tyler, W.; Ugolini, D.; Ungarelli, C.; Urbanek, K.; Vahlbruch, H.; Vallisneri, M.; van den Broeck, C.; van Putten, M.; Varvella, M.; Vass, S.; Vecchio, A.; Veitch, J.; Veitch, P.; Villar, A.; Vorvick, C.; Vyachanin, S. P.; Waldman, S. J.; Wallace, L.; Ward, H.; Ward, R.; Watts, K.; Webber, D.; Weidner, A.; Weinert, M.; Weinstein, A.; Weiss, R.; Wen, L.; Wen, S.; Wette, K.; Whelan, J. T.; Whitbeck, D.. M.; Whitcomb, S. E.; Whiting, B. F.; Wiley, S.; Wilkinson, C.; Willems, P. A.; Williams, L.; Willke, B.; Wilmut, I.; Winkler, W.; Wipf, C. C.; Wise, S.; Wiseman, A. G.; Woan, G.; Woods, D.; Wooley, R.; Worden, J.; Wu, W.; Yakushin, I.; Yamamoto, H.; Yan, Z.; Yoshida, S.; Yunes, N.; Zaleski, K. D.; Zanolin, M.; Zhang, J.; Zhang, L.; Zhao, C.; Zotov, N.; Zucker, M.; Zur Mühlen, H.; Zweizig, J.

    2007-10-01

    We carry out two searches for periodic gravitational waves using the most sensitive few hours of data from the second LIGO science run. Both searches exploit fully coherent matched filtering and cover wide areas of parameter space, an innovation over previous analyses which requires considerable algorithm development and computational power. The first search is targeted at isolated, previously unknown neutron stars, covers the entire sky in the frequency band 160 728.8 Hz, and assumes a frequency derivative of less than 4×10-10Hz/s. The second search targets the accreting neutron star in the low-mass x-ray binary Scorpius X-1 and covers the frequency bands 464 484 Hz and 604 624 Hz as well as the two relevant binary orbit parameters. Because of the high computational cost of these searches we limit the analyses to the most sensitive 10 hours and 6 hours of data, respectively. Given the limited sensitivity and duration of the analyzed data set, we do not attempt deep follow-up studies. Rather we concentrate on demonstrating the data analysis method on a real data set and present our results as upper limits over large volumes of the parameter space. In order to achieve this, we look for coincidences in parameter space between the Livingston and Hanford 4-km interferometers. For isolated neutron stars our 95% confidence level upper limits on the gravitational wave strain amplitude range from 6.6×10-23 to 1×10-21 across the frequency band; for Scorpius X-1 they range from 1.7×10-22 to 1.3×10-21 across the two 20-Hz frequency bands. The upper limits presented in this paper are the first broadband wide parameter space upper limits on periodic gravitational waves from coherent search techniques. The methods developed here lay the foundations for upcoming hierarchical searches of more sensitive data which may detect astrophysical signals.

  1. RXTE Observation of Cygnus X-1. 1; Spectral Analysis

    NASA Technical Reports Server (NTRS)

    Dove, James B.; Wilms, Joern; Nowak, Michael A.; Vaughan, Brian A.; Begelman, Mitchell C.

    1998-01-01

    We present the results of the analysis of the broad-band spectrum of Cygnus X-1 from 3.0 to 200 keV, using data from a 10 ksec observation by the Rossi X-ray Timing Explorer. The spectrum can be well described phenomenologically by an exponentially cut-off power law with a photon index Gamma = 1.45(+0.01 -0.02) (a value considerably harder 0.02 than typically found), e-folding energy E(sub f) = 162(+9 -8) keV, plus a deviation from a power law that formally can be modeled as a thermal blackbody with temperature kT(sub bb) = 1.2(+0.0 -0.1) keV. Although the 3-30 keV portion of the spectrum can be fit with a reflected power law with Gamma = 1.81 + or - 0.01 and covering fraction f = 0.35 + or - 0.02, the quality of the fit is significantly reduced when the HEXTE data in the 30-100 keV range is included, as there is no observed hardening in the power law within this energy range. As a physical description of this system, we apply the accretion disc corona models of Dove, Wilms & Begelman (1997a) - where the temperature of the corona is determined self-consistently. A spherical corona with a total optical depth pi = 1.6 + or - 0.1 and an average temperature kT(sub c) = 87 + or - 5 keV, surrounded by an exterior cold disc, does provide a good description of the data (X(exp 2 sub red) = 1.55). These models deviate from red the data by up to 7% in the 5 - 10 keV range, and we discuss possible reasons for these discrepancies. However, considering bow successfully the spherical corona reproduces the 10 - 200 keV data, such "pboton-starved" coronal geometries seem very promising for explaining the accretion processes of Cygnus X-1.

  2. Quasi-Periodic Variability in NGC 5408 X-1

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod E.; Mushotzky, Richard F.; Winter, Lisa; Soria, Roberto; Uttley, Phil; Cropper, Mark

    2007-01-01

    We report the discovery with XMM-Newton of quasiperiodic variability in the 0.2 - 10 keV X-ray flux from the ultraluminous X-ray source NGC 5408 X-1. The average power spectrum of all EPIC-pn data reveals a strong 20 mHz QPO with an average amplitude (rms) of 9%, and a coherence, Q identical with nu(sub 0)/sigma approximately equal to 6. In a 33 ksec time interval when the 20 mHz QPO is strongest we also find evidence for a 2nd QPO peak at 15 mHz, the first indication for a close pair of QPOs in a ULX source. Interestingly, the frequency ratio of this QPO pair is inconsistent with 3:2 at the 3 sigma level, but is consistent with a 4:3 ratio. A powerlaw noise component with slope near 1.5 is also present below 0.1 Hz with evidence for a break to a flatter slope at about 3 mHz. The source shows substantial broadband variability, with a total amplitude (rms) of about 30% in the 0.1 - 100 mHz frequency band, and there is strong energy dependence to the variability. The power spectrum of hard X-ray photons (greater than 2 keV) shows a "classic" flat-topped continuum breaking to a power law with index 1.5 - 2. Both the break and 20 mHz QPO are detected in the hard band, and the 20 mHz QPO is essentially at the break. The QPO is both strong and narrow in this band, having an amplitude (rms) of 15%, and Q approx. equal to 25. The energy spectrum is well fit by three components, a "cool" disk with kT = 0.15 keV, a steep power law with index 2.56, and a thermal plasma at kT = 0.87 keV. The disk, power law, and thermal plasma components contribute 35, 60, and 5% of the 0.3 - 10 keV flux, respectively. Both the timing and spectral properties of NGC 5408 X-1 are strikingly reminiscent of Galactic black hole systems at high inferred accretion rates, but with its characteristic frequencies (QPO and break frequencies) scaled down by a factor of 10 - 100. We discuss the implications of these findings in the context of models for ULXs, and their implications for the object's mass.

  3. Searching for gravitational waves from low mass x-ray binaries

    NASA Astrophysics Data System (ADS)

    Messenger, Christopher; Vecchio, Alberto

    2004-03-01

    Accreting neutron stars in binary systems, and Sco X-1 in particular, are considered one of the prime astrophysical targets for Earth-based gravitational wave laser interferometers. Here we discuss a data analysis strategy that we have developed for this class of systems which is now being applied to the science data collected by GEO600 and LIGO.

  4. Footprints of nonextensive Tsallis statistics, selfaffinity and universality in the preparation of the L’Aquila earthquake hidden in a pre-seismic EM emission

    NASA Astrophysics Data System (ADS)

    Eftaxias, K.

    2010-01-01

    Fracture induced physical fields allow a real-time monitoring of damage evolution in materials during mechanical loading. We investigate the preparation of the recently occurred L’Aquila earthquake in terms of a detected precursory electromagnetic anomaly. The precursor is well described by a recently introduced model for earthquake dynamics, which has been rooted in a nonextensive Tsallis framework starting from first principles. The analysis in terms of nonextensivity implies that the well established aspect of self-affine nature of faulting and fracture is hidden into the precursor, namely, the activation of the L’Aquila fault is a reduced self-affine image of the regional seismicity covering many geological faults. The Gutenberg-Richter magnitude-frequency relationship, the best known scaling relation for earthquakes, verifies the results based on nonextensivity. The latter suggests that the activation of the L’Aquila fault is a magnified image of the laboratory seismicity by means of acoustic and electromagnetic emissions. Finally, we present evidence for universality in magnetic storm, earthquake, and electromagnetic precursor occurrence by means of complexity and nonextensivity.

  5. Coupling between the 45 Hz Horizontal-Branch Oscillation and the Normal-Branch Oscillation in Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Yu, Wenfei

    2007-04-01

    The observations of the bright persistent neutron star low-mass X-ray binary (LMXB) Sco X-1 performed with the Rossi X-Ray Timing Explorer (RXTE) show a ~6 Hz normal-branch oscillation (NBO), a ~45 Hz horizontal-branch oscillation (HBO), and twin kilohertz quasi-periodic oscillations (kHz QPOs) on its normal branch simultaneously. We have found that the fractional amplitude of the HBO corresponding to the NBO phase of high flux is 1.1%, while that of the NBO phase of low flux is undetectable, with a 3 σ upper limit of 0.4%, implying that the HBO strength varies with the NBO phase in a manner opposite that of the lower kHz QPO previously found, and suggests that the condition for the generation of the HBO is met when the NBO flux is high. The 6 Hz NBO in Sco X-1 connects the 45 Hz HBO and the twin kHz QPO together, showing a unique picture indicating a coupling between the QPOs, which has never been observed in other neutron star LMXBs. We discuss the implications for current models of the 45 Hz HBO, the 6 Hz NBO, and the twin kHz QPOs.

  6. Confirmation via the continuum-fitting method that the spin of the black hole in Cygnus X-1 is extreme

    SciTech Connect

    Gou, Lijun; McClintock, Jeffrey E.; Steiner, James F.; Reid, Mark J.; Narayan, Ramesh; García, Javier; Remillard, Ronald A.; Orosz, Jerome A.; Hanke, Manfred

    2014-07-20

    In Gou et al., we reported that the black hole primary in the X-ray binary Cygnus X-1 is a near-extreme Kerr black hole with a spin parameter a{sub *} > 0.95 (3σ). We confirm this result while setting a new and more stringent limit: a{sub *} > 0.983 at the 3σ (99.7%) confidence level. The earlier work, which was based on an analysis of all three useful spectra that were then available, was possibly biased by the presence in these spectra of a relatively strong Compton power-law component: the fraction of the thermal seed photons scattered into the power law was f{sub s} = 23%-31%, while the upper limit for reliable application of the continuum-fitting method is f{sub s} ≲ 25%. We have subsequently obtained six additional spectra of Cygnus X-1 suitable for the measurement of spin. Five of these spectra are of high quality with f{sub s} in the range 10%-19%, a regime where the continuum-fitting method has been shown to deliver reliable results. Individually, the six spectra give lower limits on the spin parameter that range from a{sub *} > 0.95 to a{sub *} > 0.98, allowing us to conservatively conclude that the spin of the black hole is a{sub *} > 0.983 (3σ).

  7. Spectral and temporal properties of the X-ray pulsar SMC X-1 at hard X-rays

    NASA Technical Reports Server (NTRS)

    Kunz, M.; Gruber, D. E.; Kendziorra, E .; Kretschmar, P.; Maisack, M.; Mony, B.; Staubert, R.; Doebereiner, S.; Englhauser, J.; Pietsch, W.

    1993-01-01

    The binary X-ray pulsar SMC X- 1 has been observed at hard X-rays with the High Energy X-Ray Experiment (HEXE) on nine occasions between Nov. 1987 and March 1989. A thin thermal bremsstrahlung fit to the phase averaged spectrum yields a plasma temperature (14.4 +/- 1.3) keV and a luminosity above (1.1 +/- 0.1) x 10 exp 38 erg/s in the 20-80 keV band. Pulse period values have been established for three observations, confirming the remarkably stable spin-up trend of SMC X-1. In one of the three observations the pulse profile was seen to deviate from a dominant double pulsation, while at the same time the pulsed fraction was unusually large. For one observation we determined for the first time the pulsed fraction in narrow energy bands. It increases with photon energy from about 20 percent up to over 60 percent in the energy range from 20 to 80 keV.

  8. Infrared CO line for the X 1 Sigma(+) state

    NASA Technical Reports Server (NTRS)

    Goorvitch, D.

    1994-01-01

    A complete line list with improved accuracy for all the rotation-vibration transitions of the fundamental, first, and second overtone bands up to v = 20 and J = 149 of the gradual state X 1 Sigma(+) of the seven CO isotopes -- (12)C(16)O, (13)C(16)O, (12)C(17)O, (12)C(18)O, (13)C(18)O, (14)C(16)O, and (13)c(17)O -- is made available to the astronomical community. A line list of the pure rotational transitions up to v = 5 and J = 60 is also made available for these seven isotopes. This line list contains the transition frequency, the lower state energy, the Einstein A-value, the g f-value, the transition strength at 3000 K or 1000 K for the pure rotational transitions, the expectation value of the effective dipole moment operator, and the quantum numbers of each transition. Individual partition functions are reported in the temperature range of 500 to 10,000 K. This line list is available as four text files from the author using an anonymous file transfer protocol (ftp) transfer and in computer-readable form in the AAS CD-ROM Series, Vol. 3.

  9. RXTE Observation of Cygnus X-1: Spectra and Timing

    NASA Technical Reports Server (NTRS)

    Wilms, J.; Dove, J.; Nowak, M.; Vaughan, B. A.

    1997-01-01

    We present first results from the analysis of an RXTE observation of Cyg X-1 in its low state, taken about two months after the end of the high state. With Gamma approx. equal to 1.45 the spectrum is considerably harder than previous low-state measurements. The observed spectrum can be explained by a Comptonization spectrum as that emitted from a spherical corona surrounded by a cold accretion disk. The optical depth of the corona is between 2 and 2.5 and the temperature is between 60 and 80 keV. Temporal analysis shows a typical Root Mean Square (RMS) noise of approximately 25%. The Pulse Shape Discrimination (PSD) can be described as consisting of a flat component followed by an 1/f power-law, followed by an f(sup -1.6) power-law. The lag of the hard photons with respect to the soft photons is consistent with prior observations. The coherence function is remarkably close to unity from 0.01 Hz to 10 Hz.

  10. Hard X-ray spectrum of Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Nolan, P. L.; Gruber, D. E.; Knight, F. K.; Matteson, J. L.; Rothschild, R. E.; Marshall, F. E.; Levine, A. M.; Primini, F. A.

    1981-01-01

    Long-term measurements of the hard X-ray spectrum from 3 keV to 8 MeV of the black-hole candidate Cygnus X-1 in its low state are reported. Observations were made from October 26 to November 18, 1977 with the A2 (Cosmic X-ray) and A4 (Hard X-ray and Low-Energy Gamma-Ray) experiments on board HEAO 1 in the spacecraft's scanning mode. The measured spectrum below 200 keV is found to agree well with previous spectra which have been fit by a model of the Compton scattering of optical or UV photons in a very hot plasma of electron temperature 32.4 keV and optical depth 3.9 or 1.6 for spherical or disk geometry, respectively. At energies above 300 keV, however, flux excess is observed which may be accounted for by a distribution of electron temperatures from 15 to about 100 keV.

  11. Commission 42: Close Binaries

    NASA Astrophysics Data System (ADS)

    Giménez, Alvaro; Rucinski, Slavek; Szkody, P.; Gies, D.; Kang, Y.-W.; Linsky, J.; Livio, M.; Morrell, N.; Hilditch, R.; Nordström, B.; Ribas, I.; Sion, E.; Vrielman, S.

    2007-03-01

    The triennial report from Commission 42 covers various topics like massive binaries, contact systems, cataclysmic variables and low-mass binary stars. We try in a number of sections to provide an update on the current status of the main research areas in the field of close binaries. It is not a formal review, even complete or comprehensive, but an attempt to bring the main topics on recent research to astronomers working in other fields. References are also not comprehensive and simply added to the text to help the reader looking for deeper information on the subject. For this reason, we have chosen to include references (sometimes incomplete for ongoing work) not in a list at the end but integrated with the main text body. Complete references and additional sources can be easily obtained through web access of ADS or SIMBAD. Furthermore, the summary of papers on close-binary research contained in the Bibliography of Close Binaries (BCB) can be accessed from the web site of Commission 42. I would like to express the gratitude of the commission for the careful work of Colin Scarfe as Editor-in-Chief of BCB and Andras Holl and Attila Sragli for maintaining the web pages of the Commission within the structure of Division V. Finally, K. Olah and J. Jurcsik are gratefully acknowledged for their continued support as editors of the Information Bulletin on Variable Stars (IBVS), also accessible through the commission web page.

  12. Prospects for experimental research on black holes in binary systems

    NASA Technical Reports Server (NTRS)

    Long, K. S.

    1979-01-01

    Cygnus X-1, the single widely accepted example of a black hole in a binary system, is characterized by unusual X-ray properties. The X-ray spectrum of Cygnus X-1 is not cut off above 20 keV, as in most strong X-ray sources. Recent scintillation counter measurements reveal a power law spectrum extending from 40 to 200 keV with a photon spectral index of approximately 2.2. However, it is not clear that these and other X-ray properties of the system are related to the black-hole nature of Cygnus X-1. It is suggested that without a direct test to show that the mass of the compact object in other systems similar to Cygnus X-1 (Circinus X-1 and GX339-4) exceeds the limit of the neutron star mass, a better understanding of the accretion disk phenomenon must be achieved to demonstrate how the properties peculiar to these systems are related to the black hole nature of the compact object. Current accretion disk models are examined, including the alpha-accretion disk and two-temperature accretion disk models.

  13. Absorption dips at low X-ray energies in Cygnus X-1. [observed with Copernicus satellite

    NASA Technical Reports Server (NTRS)

    Murdin, P. G.

    1976-01-01

    Absorbing material in Cygnus X-1 jitters near the line joining the two stars, out of the orbital plane is described. Three looks with the Copernicus satellite at Cygnus X-1 have produced four examples of absorption dips (decreases in the 2 to 7 keV flux from Cygnus X-1 with an increase of spectral hardness consistent with photoelectric absorption).

  14. The Swift-BAT monitoring reveals a long term decay of the cyclotron line energy in Vela X-1

    NASA Astrophysics Data System (ADS)

    La Parola, V.; Cusumano, G.; Segreto, A.; D'Aì, A.

    2016-08-01

    We study the behaviour of the cyclotron resonant scattering feature (CRSF) of the high mass X-ray binary Vela X-1 using the long-term hard X-ray monitoring performed by the Burst Alert Telescope (BAT) on board Swift. High statistics, intensity selected spectra were built along 11 years of BAT survey. While the fundamental line is not revealed, the second harmonic of the CRSF can be clearly detected in all the spectra, at an energy varying between ˜53 keV and ˜58 keV, directly correlated with the luminosity. We have further investigated the evolution of the CRSF in time, by studying the intensity selected spectra built along four 33-month time intervals along the survey. For the first time we find in this source a secular variation in the CRSF energy: independent of the source luminosity, the CRSF second harmonic energy decreases by ˜0.36 keV/year between the first and the third time interval, corresponding to an apparent decay of the magnetic field of ˜3 × 1010 G/year. The intensity-cyclotron energy pattern is consistent between the third and the last time intervals. A possible interpretation for this decay could be the settling of an accreted mound that produces either a distortion of the poloidal magnetic field on the polar cap or a geometrical displacement of the line forming region. This hypothesis seems supported by the correspondance between the rate of the line shift per unit accreted mass and the mass accreted on the polar cap per unit area in Vela X-1 and Her X-1, respectively.

  15. Energy-dependent evolution in IC10 X-1: hard evidence for an extended corona and implications

    SciTech Connect

    Barnard, R.; Steiner, J. F.; Prestwich, A. F.; Stevens, I. R.; Clark, J. S.; Kolb, U. C.

    2014-09-10

    We have analyzed a ∼130 ks XMM-Newton observation of the dynamically confirmed black hole + Wolf-Rayet (BH+WR) X-ray binary (XB) IC10 X-1, covering ∼1 orbital cycle. This system experiences periodic intensity dips every ∼35 hr. We find that energy-independent evolution is rejected at a >5σ level. The spectral and timing evolution of IC10 X-1 are best explained by a compact disk blackbody and an extended Comptonized component, where the thermal component is completely absorbed and the Comptonized component is partially covered during the dip. We consider three possibilities for the absorber: cold material in the outer accretion disk, as is well documented for Galactic neutron star (NS) XBs at high inclination; a stream of stellar wind that is enhanced by traveling through the L1 point; and a spherical wind. We estimated the corona radius (r {sub ADC}) for IC10 X-1 from the dip ingress to be ∼10{sup 6} km, assuming absorption from the outer disk, and found it to be consistent with the relation between r {sub ADC} and 1-30 keV luminosity observed in Galactic NS XBs that spans two orders of magnitude. For the other two scenarios, the corona would be larger. Prior BH mass (M {sub BH}) estimates range over 23-38 M {sub ☉}, depending on the inclination and WR mass. For disk absorption, the inclination, i, is likely to be ∼60-80°, with M {sub BH} ∼ 24-41 M {sub ☉}. Alternatively, the L1-enhanced wind requires i ∼ 80°, suggesting ∼24-33 M {sub ☉}. For a spherical absorber, i ∼ 40°, and M {sub BH} ∼ 50-65 M {sub ☉}.

  16. The Soft State of Cygnus X-1 Observed with NuSTAR: A Variable Corona and a Stable Inner Disk

    NASA Astrophysics Data System (ADS)

    Walton, D. J.; Tomsick, J. A.; Madsen, K. K.; Grinberg, V.; Barret, D.; Boggs, S. E.; Christensen, F. E.; Clavel, M.; Craig, W. W.; Fabian, A. C.; Fuerst, F.; Hailey, C. J.; Harrison, F. A.; Miller, J. M.; Parker, M. L.; Rahoui, F.; Stern, D.; Tao, L.; Wilms, J.; Zhang, W.

    2016-07-01

    We present a multi-epoch hard X-ray analysis of Cygnus X-1 in its soft state based on four observations with the Nuclear Spectroscopic Telescope Array (NuSTAR). Despite the basic similarity of the observed spectra, there is clear spectral variability between epochs. To investigate this variability, we construct a model incorporating both the standard disk-corona continuum and relativistic reflection from the accretion disk, based on prior work on Cygnus X-1, and apply this model to each epoch independently. We find excellent consistency for the black hole spin and the iron abundance of the accretion disk, which are expected to remain constant on observational timescales. In particular, we confirm that Cygnus X-1 hosts a rapidly rotating black hole, 0.93≲ {a}* ≲ 0.96, in broad agreement with the majority of prior studies of the relativistic disk reflection and constraints on the spin obtained through studies of the thermal accretion disk continuum. Our work also confirms the apparent misalignment between the inner disk and the orbital plane of the binary system reported previously, finding the magnitude of this warp to be ˜10°–15°. This level of misalignment does not significantly change (and may even improve) the agreement between our reflection results and the thermal continuum results regarding the black hole spin. The spectral variability observed by NuSTAR is dominated by the primary continuum, implying variability in the temperature of the scattering electron plasma. Finally, we consistently observe absorption from ionized iron at ˜6.7 keV, which varies in strength as a function of orbital phase in a manner consistent with the absorbing material being an ionized phase of the focused stellar wind from the supergiant companion star.

  17. The Soft State of Cygnus X-1 Observed with NuSTAR: A Variable Corona and a Stable Inner Disk

    NASA Astrophysics Data System (ADS)

    Walton, D. J.; Tomsick, J. A.; Madsen, K. K.; Grinberg, V.; Barret, D.; Boggs, S. E.; Christensen, F. E.; Clavel, M.; Craig, W. W.; Fabian, A. C.; Fuerst, F.; Hailey, C. J.; Harrison, F. A.; Miller, J. M.; Parker, M. L.; Rahoui, F.; Stern, D.; Tao, L.; Wilms, J.; Zhang, W.

    2016-07-01

    We present a multi-epoch hard X-ray analysis of Cygnus X-1 in its soft state based on four observations with the Nuclear Spectroscopic Telescope Array (NuSTAR). Despite the basic similarity of the observed spectra, there is clear spectral variability between epochs. To investigate this variability, we construct a model incorporating both the standard disk-corona continuum and relativistic reflection from the accretion disk, based on prior work on Cygnus X-1, and apply this model to each epoch independently. We find excellent consistency for the black hole spin and the iron abundance of the accretion disk, which are expected to remain constant on observational timescales. In particular, we confirm that Cygnus X-1 hosts a rapidly rotating black hole, 0.93≲ {a}* ≲ 0.96, in broad agreement with the majority of prior studies of the relativistic disk reflection and constraints on the spin obtained through studies of the thermal accretion disk continuum. Our work also confirms the apparent misalignment between the inner disk and the orbital plane of the binary system reported previously, finding the magnitude of this warp to be ∼10°–15°. This level of misalignment does not significantly change (and may even improve) the agreement between our reflection results and the thermal continuum results regarding the black hole spin. The spectral variability observed by NuSTAR is dominated by the primary continuum, implying variability in the temperature of the scattering electron plasma. Finally, we consistently observe absorption from ionized iron at ∼6.7 keV, which varies in strength as a function of orbital phase in a manner consistent with the absorbing material being an ionized phase of the focused stellar wind from the supergiant companion star.

  18. Determination of Black Hole Mass in Cyg X-1 by Scaling of Spectral Index-QPO Frequency Correlation

    NASA Technical Reports Server (NTRS)

    Shaposhnikov, Nickolai; Titarchuk, Lev

    2007-01-01

    It is well established that timing and spectral properties of Galactic Black Hole (BH) X-ray binaries (XRB) are strongly correlated. In particular, it has been shown that low frequency Quasi-Periodic Oscillation (QPO) nu(sub low) - photon index GAMMA correlation curves have a specific pattern. In a number of the sources studied the shape of the index-low frequency QPO correlations are self-similar with a position offset in the nu(sub low) - GAMMA plane determined by a BH mass M(sub BH). Specifically, Titarchuk & Fiorito (2004) gave strong theoretical and observational arguments that the QPO frequency values in this nu(sub low) - GAMMA correlation should be inversely proportional to M(sub BH). A simple translation of the correlation for a given source along frequency axis leads to the observed correlation for another source. As a result of this translation one can obtain a scaling factor which is simply a BH mass ratio for these particular sources. This property of the correlations offers a fundamentally new method for BH mass determination in XRBs. Here we use the observed QPO-index correlations observed in three BH sources: GRO J1655-40, GRS 1915+105 and Cyg X-1. The BH mass of (6.3 plus or minus 0.5) solar mass in GRO J1655-40 is obtained using optical observations. RXTE observations during the recent 2005 outburst yielded sufficient data to establish the correlation pattern during both rise and decay of the event. We use GRO J1655-40 as a standard reference source to measure the BH mass in Cyg X-1. We also revisit the GRS 1915+105 data as a further test of our scaling method. We obtain the BH mass in Cyg X-1 in the range 7.6-9.9.

  19. Cygnus X-1: A Case for a Magnetic Accretion Disk?

    NASA Technical Reports Server (NTRS)

    Nowak, Michael A.; Vaughan, B. A.; Dove, J.; Wilms, J.

    1996-01-01

    With the advent of Rossi X-ray Timing Explorer (RXTE), which is capable of broad spectral coverage and fast timing, as well as other instruments which are increasingly being used in multi-wavelength campaigns (via both space-based and ground-based observations), we must demand more of our theoretical models. No current model mimics all facets of a system as complex as an x-ray binary. However, a modern theory should qualitatively reproduce - or at the very least not fundamentally disagree with - all of Cygnus X-l's most basic average properties: energy spectrum (viewed within a broader framework of black hole candidate spectral behavior), power spectrum (PSD), and time delays and coherence between variability in different energy bands. Below we discuss each of these basic properties in turn, and we assess the health of one of the currently popular theories: Comptonization of photons from a cold disk. We find that the data pose substantial challenges for this theory, as well as all other in currently discussed models.

  20. SAS 3 observations of Cygnus X-1 - The intensity dips

    NASA Technical Reports Server (NTRS)

    Remillard, R. A.; Canizares, C. R.

    1984-01-01

    In general, the dips are observed to occur near superior conjunctions of the X-ray source, but one pair of 2-minute dips occurs when the X-ray source is closer to the observer than is the supergiant companion. The dips are analyzed spectrally with the aid of seven energy channels in the range 1.2-50 keV. Essentially, there is no change in the spectral index during the dips. Reductions in the count rates are observed at energies exceeding 6 keV for some of the dips, but the dip amplitude is always significantly greater in the 1.2-3 keV band. It is believed that absorption by partially ionized gas may best explain these results, since the observations of Pravdo et al. (1980) rule out absorption by unionized material. Estimates for the intervening gas density, extent, and distance from the X-ray source are presented. Attention is also given to the problems confronting the models for the injection of gas through the line of sight, believed to be inclined by approximately 30 deg from the binary pole.

  1. The Microquasar Cyg X-1: A Short Review

    NASA Technical Reports Server (NTRS)

    Nowak, M. A.; Wilms, J.; Hanke, M.; Pottschmidt, K.; Markoff, S.

    2011-01-01

    We review the spectral properties of the black hole candidate Cygnus X-I. Specifically, we discuss two recent sets of multi-satellite observations. One comprises a 0.5-500 keY spectrum, obtained with eve!)' flying X-ray satellite at that time, that is among the hardest Cyg X-I spectra observed to date. The second set is comprised of 0.5-40 keV Chandra-HETG plus RXTE-PCA spectra from a radio-quiet, spectrally soft state. We first discuss the "messy astrophysics" often neglected in the study of Cyg X-I, i.e., ionized absorption from the wind of the secondary and the foreground dust scattering halo. We then discuss components common to both state extremes: a low temperature accretion disk, and a relativistically broadened Fe line and reflection. Hard state spectral models indicate that the disk inner edge does not extend beyond > or approx.= 40 GM/sq c , and may even approach as close as approx. = 6GM/sq c. The soft state exhibits a much more prominent disk component; however, its very low normalization plausibly indicates a spinning black hole in the Cyg X-I system. Key words. accretion, accretion disks - black hole physics - X-rays:binaries

  2. Binary ferrihydrite catalysts

    DOEpatents

    Huffman, Gerald P.; Zhao, Jianmin; Feng, Zhen

    1996-01-01

    A method of preparing a catalyst precursor comprises dissolving an iron salt and a salt of an oxoanion forming agent, in water so that a solution of the iron salt and oxoanion forming agent salt has a ratio of oxoanion/Fe of between 0.0001:1 to 0.5:1. Next is increasing the pH of the solution to 10 by adding a strong base followed by collecting of precipitate having a binary ferrihydrite structure. A binary ferrihydrite catalyst precursor is also prepared by dissolving an iron salt in water. The solution is brought to a pH of substantially 10 to obtain ferrihydrite precipitate. The precipitate is then filtered and washed with distilled water and subsequently admixed with a hydroxy carboxylic acid solution. The admixture is mixed/agitated and the binary ferrihydrite precipitate is then filtered and recovered.

  3. Binary ferrihydrite catalysts

    DOEpatents

    Huffman, G.P.; Zhao, J.; Feng, Z.

    1996-12-03

    A method of preparing a catalyst precursor comprises dissolving an iron salt and a salt of an oxoanion forming agent, in water so that a solution of the iron salt and oxoanion forming agent salt has a ratio of oxoanion/Fe of between 0.0001:1 to 0.5:1. Next is increasing the pH of the solution to 10 by adding a strong base followed by collecting of precipitate having a binary ferrihydrite structure. A binary ferrihydrite catalyst precursor is also prepared by dissolving an iron salt in water. The solution is brought to a pH of substantially 10 to obtain ferrihydrite precipitate. The precipitate is then filtered and washed with distilled water and subsequently admixed with a hydroxy carboxylic acid solution. The admixture is mixed/agitated and the binary ferrihydrite precipitate is then filtered and recovered. 3 figs.

  4. Simulating Contact Binaries

    NASA Astrophysics Data System (ADS)

    Kadam, Kundan; Clayton, Geoffrey C.; Frank, Juhan; Tohline, Joel E.; Staff, Jan E.; Motl, Patrick M.; Marcello, Dominic

    2014-06-01

    About one in every 150 stars is a contact binary system of WUMa type and it was thought for a long time that such a binary would naturally proceed towards merger, forming a single star. In September 2008 such a merger was observed in the eruption of a “red nova", V1309 Sco. We are developing a hydrodynamics simulation for contact binaries using Self Consistent Field (SCF) techniques, so that their formation, structural, and merger properties could be studied. This model can also be used to probe the stability criteria such as the large-scale equatorial circulations and the minimum mass ratio. We also plan to generate light curves from the simulation data in order to compare with the observed case of V1309 Sco. A comparison between observations and simulations will help us better understand the nova-like phenomena of stellar mergers.

  5. Anisotropy of partially self-absorbed jets and the jet of Cyg X-1

    NASA Astrophysics Data System (ADS)

    Zdziarski, Andrzej A.; Paul, Debdutta; Osborne, Ruaraidh; Rao, A. R.

    2016-08-01

    We study the angular dependence of the flux from partially synchrotron self-absorbed conical jets (proposed by Blandford & Königl). We consider the jet viewed from either a side or close to on axis, and in the latter case, either from the jet top or bottom. We derive analytical formulae for the flux in each of these cases, and find the exact solution for an arbitrary angle numerically. We find that the maximum of the emission occurs when the jet is viewed from top on-axis, which is contrast to a previous result, which found the maximum at some intermediate angle and null emission on-axis. We then calculate the ratio of the jet-to-counterjet emission for this model, which depends on the viewing angle and the index of power-law electrons. We apply our results to the black-hole binary Cyg X-1. Given the jet-to-counterjet flux ratio of ga50 found observationally and the current estimates of the inclination, we find the jet velocity to be ≳ 0.8c. We also point out that when the projection effect is taken into account, the radio observations imply the jet half-opening angle of ≲ 1°, a half of the value given before. When combined with the existing estimates of Γj, the jet half-opening angle is low, ≪1/Γj, and much lower than values observed in blazars, unless Γj is much higher than currently estimated.

  6. Identification list of binaries

    NASA Astrophysics Data System (ADS)

    Malkov,, O.; Karchevsky,, A.; Kaygorodov, P.; Kovaleva, D.

    The Identification List of Binaries (ILB) is a star catalogue constructed to facilitate cross-referencing between different catalogues of binary stars. As of 2015, it comprises designations for approximately 120,000 double/multiple systems. ILB contains star coordinates and cross-references to the Bayer/Flemsteed, DM (BD/CD/CPD), HD, HIP, ADS, WDS, CCDM, TDSC, GCVS, SBC9, IGR (and some other X-ray catalogues), PSR designations, as well as identifications in the recently developed BSDB system. ILB eventually became a part of the BDB stellar database.

  7. The Variable Warm Absorber in Circinus X-1

    NASA Astrophysics Data System (ADS)

    Schulz, N. S.; Kallman, T. E.; Galloway, D. K.; Brandt, W. N.

    2008-01-01

    We observed Circinus X-1 twice during a newly reached low-flux phase near zero orbital phase using the High-Energy Transmission Grating Spectrometer (HETGS) onboard Chandra. In both observations the source did not show the P Cygni lines we observed during the high-flux phases of the source in 2000 and 2001. During the prezero phase the source did not exhibit significant variability but did exhibit an emission-line spectrum rich in H- and He-like lines from high-Z elements such as Si, S, Ar, and Ca. The light curve in the postdip observation showed quiescent and flaring episodes. Only in these flaring episodes was the source luminosity significantly higher than observed during the prezero phase. We analyzed all high-resolution X-ray spectra by fitting photoionization and absorption models from the most recent version of the XSTAR code. The prezero-phase spectrum could be fully modeled with a very hot photoionized plasma with an ionization parameter of log ξ = 3.0, down from log ξ = 4.0 in the high-flux state. The ionization balances we measure from the spectra during the postzero-phase episodes are significantly different. Both episodes feature absorbers with variable high columns, ionization parameters, and luminosity. While cold absorption remains at levels quite similar to that observed in previous years, the new observations show unprecedented levels of variable warm absorption. The line emissivities also indicate that the observed low source luminosity is inconsistent with a static hot accretion disk corona (ADC), an effect that seems common to other near-edge-on ADC sources as well. We conclude that unless there exists some means of coronal heating other than X-rays, the true source luminosity is likely much higher, and we observe obscuration in analogy to the extragalactic Seyfert 2 sources. We discuss possible consequences and relate cold, lukewarm, warm, and hot absorbers to dynamic accretion scenarios.

  8. PULSAR BINARY BIRTHRATES WITH SPIN-OPENING ANGLE CORRELATIONS

    SciTech Connect

    O'Shaughnessy, Richard; Kim, Chunglee E-mail: ckim@astro.lu.s

    2010-05-20

    One ingredient in an empirical birthrate estimate for pulsar binaries is the fraction of sky subtended by the pulsar beam: the pulsar beaming fraction. This fraction depends on both the pulsar's opening angle and the misalignment angle between its spin and magnetic axes. The current estimates for pulsar binary birthrates are based on an average value of beaming fractions for only two pulsars, i.e., PSRs B1913+16 and B1534+12. In this paper, we revisit the observed pulsar binaries to examine the sensitivity of birthrate predictions to different assumptions regarding opening angle and alignment. Based on empirical estimates for the relative likelihood of different beam half-opening angles and misalignment angles between the pulsar rotation and magnetic axes, we calculate an effective beaming correction factor, f{sub b,eff}, whose reciprocal is equivalent to the average fraction of all randomly selected pulsars that point toward us. For those pulsars without any direct beam geometry constraints, we find that f{sub b,eff} is likely to be smaller than 6, a canonically adopted value when calculating birthrates of Galactic pulsar binaries. We calculate f{sub b,eff} for PSRs J0737-3039A and J1141-6545, applying the currently available constraints for their beam geometry. As in previous estimates of the posterior probability density function P(R) for pulsar binary birthrates R, PSRs J0737-3039A and J1141-6545 still significantly contribute to, if not dominate, the Galactic birthrate of tight pulsar-neutron star (NS) and pulsar-white dwarf (WD) binaries, respectively. Our median posterior present-day birthrate predictions for tight PSR-NS binaries, wide PSR-NS binaries, and tight PSR-WD binaries given a preferred pulsar population model and beaming geometry are 89 Myr{sup -1}, 0.5 Myr{sup -1}, and 34 Myr{sup -1}, respectively. For long-lived PSR-NS binaries, these estimates include a weak (x1.6) correction for slowly decaying star formation in the galactic disk. For pulsars

  9. Long-term change in the cyclotron line energy in Hercules X-1

    NASA Astrophysics Data System (ADS)

    Staubert, R.; Klochkov, D.; Wilms, J.; Postnov, K.; Shakura, N. I.; Rothschild, R. E.; Fürst, F.; Harrison, F. A.

    2014-12-01

    Aims: We investigate the long-term evolution of the cyclotron resonance scattering feature (CRSF) in the spectrum of the binary X-ray pulsar Her X-1 and present evidence of a true long-term decrease in the centroid energy Ecyc of the cyclotron line in the pulse phase averaged spectra from 1996 to 2012. Methods: Our results are based on repeated observations of Her X-1 by those X-ray observatories capable of measuring clearly beyond the cyclotron line energy of ~40 keV; these are RXTE, INTEGRAL, Suzaku, and NuSTAR. We consider results based on our own successful observing proposals as well as results from the literature. Results: The historical evolution of the pulse phase averaged CRSF centroid energy Ecyc since its discovery in 1976 is characterized by an initial value around 35 keV, an abrupt jump upwards to beyond ~40 keV between 1990 and 1994, and an apparent decay thereafter. Much of this decay, however, was found to be due to an artifact, namely a correlation between Ecyc and the X-ray luminosity Lx discovered in 2007. In observations after 2006, however, we now find a statistically significant true decrease in the cyclotron line energy. At the same time, the dependence of Ecyc on X-ray luminosity is still valid with an increase of ~5% in energy for a factor of two increase in luminosity. We also report on the first evidence of a weak dependence of Ecyc on phase of the 35 d precessional period, which manifests itself not only in the modulation of the X-ray flux, but also in the systematic variation in the shape of the 1.24 s pulse profile. One of our motivations for repeatedly observing Her X-1, namely the suspicion that the cyclotron line energy may be gradually decreasing after its strong upward jump in the early 1990s, is finally confirmed. A decrease in Ecyc by 4.2 keV over the 16 years from 1996 to 2012 can either be modeled by a linear decay, or by a slow decay until 2006 followed by a more abrupt decrease thereafter. Conclusions: The observed timescale

  10. Participation of the Abastumani Astrophysical Observatory in Different Programs for Coordinated Investigation of Cyg X-1

    NASA Astrophysics Data System (ADS)

    Kumsiashvili, M. I.; Kochiashvili, N. T.

    2000-10-01

    Broad-band photometric observations of the black hole candidate Cyg X-1 were carried out in 1975-1998 at the Abastumani Astrophysical Observatory in the framework of coordinated observations, at the varies observatories of the former Soviet Union. All data have been reduced to a homogeneous set.Comparison of the optical and X-ray data clearly shows the existence of several kinds of variability. Analysis of the prolonged photoelectric observations of V 1357 Cyg=Cyg X-1 confirmed long-period optical variation of this X-ray binary system with the period of 294 d revealed by Kemp et al. This periodicity is most strongly pronounced at the orbital period phase when the optical star is in front of the X-ray source. Variations of the mean level of Cyg X-1 and of the light curve form with the phase of the period 294 d agree well with the model of the precessing accretion disk which radiates in the optical range mainly by scattering and processing of the optical star radiation. The direction of the disc precession coincides with that of the orbital motion and it is hard to understand this fact in the models with the forced precession. The triple system model is less probable. There are also observations of this objects made in the Abastumani Observatory in 1982-1988 which are represented the Table and light curves. These observations have not discussed by coordinators. The observations taken in the course of the International campaign "The Optical Monitoring of the Unique Astrophysical Objects" were realized by the observatories located on the territories of Georgia, Russia, Uzbekistan and Ukraine in 1994-1998. They are united in a single set, taking into account the systemic differences between them. Number of usual observations is 2247 in 399 nights in U B V R bands. The observations were performed simultaneously in X-ray band in the energy range of 2-10 keV (ASM/RXTE), and 20-100 keV (BASTE/CGRO), and also with radio observations at the Mullard radio observatory. Our

  11. Risk Communication on Earthquake Prediction Studies -"No L'Aquila quake risk" experts probed in Italy in June 2010

    NASA Astrophysics Data System (ADS)

    Oki, S.; Koketsu, K.; Kuwabara, E.; Tomari, J.

    2010-12-01

    For the previous 6 months from the L'Aquila earthquake which occurred on 6th April 2009, the seismicity in that region had been active. Having become even more active and reached to magnitude 4 earthquake on 30th March, the government held Major Risks Committee which is a part of the Civil Protection Department and is tasked with forecasting possible risks by collating and analyzing data from a variety of sources and making preventative recommendations. At the press conference immediately after the committee, they reported that "The scientific community tells us there is no danger, because there is an ongoing discharge of energy. The situation looks favorable." 6 days later, a magunitude 6.3 earthquake attacked L'Aquila and killed 308 people. On 3rd June next year, the prosecutors opened the investigation after complaints of the victims that far more people would have fled their homes that night if there had been no reassurances of the Major Risks Committee the previous week. This issue becomes widely known to the seismological society especially after an email titled "Letter of Support for Italian Earthquake Scientists" from seismologists at the National Geophysics and Volcanology Institute (INGV) sent worldwide. It says that the L'Aquila Prosecutors office indicted of manslaughter the members of the Major Risks Committee and that the charges are for failing to provide a short term alarm to the population before the earthquake struck. It is true that there is no generalized method to predict earthquakes but failing the short term alarm is not the reason for the investigation of the scientists. The chief prosecutor stated that "the committee could have provided the people with better advice", and "it wasn't the case that they did not receive any warnings, because there had been tremors". The email also requests sign-on support for the open letter to the president of Italy from Earth sciences colleagues from all over the world and collected more than 5000 signatures

  12. Lessons from the conviction of the L'Aquila seven: The standard probabilistic earthquake hazard and risk assessment is ineffective

    NASA Astrophysics Data System (ADS)

    Wyss, Max

    2013-04-01

    An earthquake of M6.3 killed 309 people in L'Aquila, Italy, on 6 April 2011. Subsequently, a judge in L'Aquila convicted seven who had participated in an emergency meeting on March 30, assessing the probability of a major event to follow the ongoing earthquake swarm. The sentence was six years in prison, a combine fine of 2 million Euros, loss of job, loss of retirement rent, and lawyer's costs. The judge followed the prosecution's accusation that the review by the Commission of Great Risks had conveyed a false sense of security to the population, which consequently did not take their usual precautionary measures before the deadly earthquake. He did not consider the facts that (1) one of the convicted was not a member of the commission and had merrily obeyed orders to bring the latest seismological facts to the discussion, (2) another was an engineer who was not required to have any expertise regarding the probability of earthquakes, (3) and two others were seismologists not invited to speak to the public at a TV interview and a press conference. This exaggerated judgment was the consequence of an uproar in the population, who felt misinformed and even mislead. Faced with a population worried by an earthquake swarm, the head of the Italian Civil Defense is on record ordering that the population be calmed, and the vice head executed this order in a TV interview one hour before the meeting of the Commission by stating "the scientific community continues to tell me that the situation is favorable and that there is a discharge of energy." The first lesson to be learned is that communications to the public about earthquake hazard and risk must not be left in the hands of someone who has gross misunderstandings about seismology. They must be carefully prepared by experts. The more significant lesson is that the approach to calm the population and the standard probabilistic hazard and risk assessment, as practiced by GSHAP, are misleading. The later has been criticized as

  13. Is the April 6th 2009 L'Aquila earthquake a confirmation of the "seismic landscape" concept?

    NASA Astrophysics Data System (ADS)

    Blumetti, Anna Maria; Comerci, Valerio; Guerrieri, Luca; Michetti, Alessandro Maria; Serva, Leonello; Vittori, Eutizio

    2010-05-01

    In the Central Apennines, active extensional tectonics is accommodated by a dense array of normal faults. Major tectonic elements are typically located at the foot of fault escarpments, tens of kilometres long and some hundreds of meters high. Subordinate faults within major blocks produce additional topographic irregularities (i.e., minor graben and fault scarps; Blumetti et al. 1993; Serva et al. 2002; Blumetti and Guerrieri, 2007). During moderate to strong earthquakes (M>6) one or several or all these faults can be rejuvenated up to the surface, and should be therefore regarded as capable faults. Thus, their total throw is the result of several surface faulting events over the last few hundreds of thousands of years. This is true for landscapes that have a "typical" earthquake magnitude (i.e., the earthquake magnitude that better "characterizes" the local landscape; Serva et al. 2002; Michetti et al. 2005) of either 6 or 7. According to this model in the L'Aquila region the seismic landscape is the result of repeated magnitude 7 events. In other words, the maximum magnitude to be expected is around 7, but clearly smaller events can also occur, like in the April 6, 2009 case. The L'Aquila region is well known for being characterized by a high seismic hazard. In particular, two events with Intensity X MCS occurred on November 26, 1461 and February 2, 1703. The latter was the third major seismic event of a seismic sequence that in two weeks shifted from Norcia (January 14) to L'Aquila (February 2). Two other destructive earthquakes hit the same area in 1349, IX-X MCS, and in 1762, IX MCS. Concerning the February 2, 1703, event, a good dataset of geological effects was provided by contemporary reports (e.g. Uria de Llanos, 1703): about 20 km of surface faulting along the Pizzoli fault, with offsets up to about half a meter and impressive secondary effects such as a river diversion, huge deep-seated gravitational movements and liquefaction phenomena involving the

  14. Binary coding for hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Chang, Chein-I.; Chang, Chein-Chi; Lin, Chinsu

    2004-10-01

    Binary coding is one of simplest ways to characterize spectral features. One commonly used method is a binary coding-based image software system, called Spectral Analysis Manager (SPAM) for remotely sensed imagery developed by Mazer et al. For a given spectral signature, the SPAM calculates its spectral mean and inter-band spectral difference and uses them as thresholds to generate a binary code word for this particular spectral signature. Such coding scheme is generally effective and also very simple to implement. This paper revisits the SPAM and further develops three new SPAM-based binary coding methods, called equal probability partition (EPP) binary coding, halfway partition (HP) binary coding and median partition (MP) binary coding. These three binary coding methods along with the SPAM well be evaluated for spectral discrimination and identification. In doing so, a new criterion, called a posteriori discrimination probability (APDP) is also introduced for performance measure.

  15. Fast Determination of Moment Tensors and Rupture History: Application to the April 6th 2009, L’Aquila Earthquake

    NASA Astrophysics Data System (ADS)

    Scognamiglio, L.; Tinti, E.; Michelini, A.; Dreger, D. S.; Cirella, A.; Cocco, M.; Faenza, L.; Mazza, S.

    2009-12-01

    On April 6th 2009, a magnitude Mw=6.3 earthquake struck the Abruzzi region in central Italy. Despite its moderate size, the earthquake caused 293 fatalities and partially destroyed the city of L’Aquila and many villages in its surroundings. The main shock was preceded by an earthquake swarm, which started at the end of 2008. The largest earthquakes of the swarm occurred on 2009/03/30 (ML=4.1), and on 2009/04/05 (ML=3.9). To date, almost 7,000 aftershocks with ML>1.5 have been recorded by the INGV seismic network and three featured ML larger than 5.0. In this study, we present the results of the fast source parameters determination procedure adopted at the Istituto Nazionale di Geofisica e Vulcanologia (INGV) using the 2009 L’Aquila earthquake as a case study. The main task of this procedure is the fast calculation of source parameters within the first 24 hours after an earthquake. We apply a time domain moment tensor (TDMT) technique to compute the focal mechanisms of all the ML≥ 3.9 earthquakes by inverting broadband records of the Italian national seismic network. All events show normal faulting in agreement with the tectonic setting of the area. The preferred main shock moment tensor solution inferred is: strike 139°, dip 48°, rake -77° and Mw= 6.1. Using the main shock moment tensor to constrain the fault geometry, we invert the strong motion data provided by the Rete Accelerometrica Nazionale (RAN) and the MedNet station AQU to image the rupture history. The inferred model is representative of a rapid finite-fault solution to be used immediately after an earthquake to get a preliminary interpretation of ground shaking. The proposed rupture history highlights several relevant features. First, we have identified the SW dipping plane as the main shock rupture plane and the existence of rupture directivity associated with both the up-dip and SE along-strike propagation. Second, the inferred rupture velocity, constant all over the fault plane, is

  16. Separation in Binary Alloys

    NASA Technical Reports Server (NTRS)

    Frazier, D. O.; Facemire, B. R.; Kaukler, W. F.; Witherow, W. K.; Fanning, U.

    1986-01-01

    Studies of monotectic alloys and alloy analogs reviewed. Report surveys research on liquid/liquid and solid/liquid separation in binary monotectic alloys. Emphasizes separation processes in low gravity, such as in outer space or in free fall in drop towers. Advances in methods of controlling separation in experiments highlighted.

  17. Binary concatenated coding system

    NASA Technical Reports Server (NTRS)

    Monford, L. G., Jr.

    1973-01-01

    Coding, using 3-bit binary words, is applicable to any measurement having integer scale up to 100. System using 6-bit data words can be expanded to read from 1 to 10,000, and 9-bit data words can increase range to 1,000,000. Code may be ''read'' directly by observation after memorizing simple listing of 9's and 10's.

  18. Binary primitive alternant codes

    NASA Technical Reports Server (NTRS)

    Helgert, H. J.

    1975-01-01

    In this note we investigate the properties of two classes of binary primitive alternant codes that are generalizations of the primitive BCH codes. For these codes we establish certain equivalence and invariance relations and obtain values of d and d*, the minimum distances of the prime and dual codes.

  19. Interacting binaries. Lecture notes 1992.

    NASA Astrophysics Data System (ADS)

    Nussbaumer, H.; Orr, A.

    These lecture notes represent a unique collection of information and references on current research on interacting binaries: S. N. Shore puts the emphasis on observations and their connection to relevant physics. He also discusses symbiotic stars. Cataclysmic variables are the subject of M. Livio's course, whereas E. P. J. van den Heuvel concentrates on more massive binaries and X-ray binaries.

  20. WISE Detection of Low-Mass X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Wang, Zhongxiang

    2014-08-01

    I will report on the results from our search for the Wide-field Infrared Survey Explorer detection of the Galactic low-mass X-ray binaries. Among 187 catalogued binaries, we find 13 counterparts and two candidate counterparts. For the 13 counterparts, two (4 0614+091 and G 339-4) have already been confirmed by previous studies to have a jet and one (GR 1915+105) to have a candidate circumbinary disk, from which the detected infrared emission arose. Having collected the broad-band optical and near-infrared data in literature and constructed flux density spectra for the other 10 binaries, we identify that three (A0620-00, XTE J1118+480, and GX 1+4) are candidate circumbinary disk systems, four (Cen X-4, 4U 1700+24, 3A 1954+319, and Cyg X-2) had thermal emission from their companion stars, and three (Sco X-1, Her X-1, and Swift J1753.5-0127) are peculiar systems with the origin of their infrared emission rather uncertain. Discussion of the results and WISE counterparts' brightness distribution will be provided, which suggests that more than half of the LMXBs would have a jet, a circumbinary disk, or the both.

  1. Radio observations of comet C/2012 X1 LINEAR

    NASA Astrophysics Data System (ADS)

    Lovell, A.; Howell, E.

    2014-07-01

    We obtained radio OH spectra of comet C/2012 X1 LINEAR between 03 November 2013 and 13 January 2014 with the 305-m Gordon Telescope at Arecibo Observatory. Spectra at 1667 and 1665 MHz (18-cm wavelength) were obtained with an on-sky beam size of 2.9' and spectral resolution of 0.1 km s^{-1}, on most occasions mapping 7 positions of the OH coma within 4' of the nucleus. The observation range spans heliocentric distances from 2.2 au down to 1.7 au pre-perihelion, and geocentric distances ranging from 2.8-2.2 au, yielding a resolution of 300-400,000 km at the comet. Radio OH spectra are seen via a λ-doublet, with the excitation of the lines depending on the heliocentric velocity of the comet, changing the relative velocity of the cometary gas with respect to the UV spectrum of the Sun. We interpret the spectra via a vectorial Monte Carlo model, taking into account the OH inversion predictions of Despois et al. [1] as well as Schleicher & A'Hearn [2]. In highly productive comets, larger coma densities thermalize the line excitation, reducing the observed line strength near the nucleus. We treat this collisional quenching following that outlined by Schloerb [3] and Gérard [4]. Mapping observations can directly constrain the radius within which quenching is active, and thus yield a more accurate estimate of the gas production rate. Radio observations at high spectral resolution place excellent constraints on the gas outflow velocity in cometary comae. Best-fit models for these observations, processed based on spectra binned to a resolution of 0.34 km s^{-1}, yield gas outflow velocity of 0.78 ± 0.03 km s^{-1}, typical for comets outside 1 au heliocentric distance, and consistent with those of Tseng et al. [5]. Gas production rates differ by 20-30 percent for the two inversion models, but range between 2 × 10^{28} and 4 × 10^{28} mol s^{-1}, also similar to other comets observed at these heliocentric distances. We will present spectral line maps for these

  2. From Colfiorito to L'Aquila Earthquake: learning from the past to communicating the risk of the present

    NASA Astrophysics Data System (ADS)

    Lanza, T.; Crescimbene, M.; La Longa, F.

    2012-04-01

    Italy is a country at risk of impending earthquake in the near future. Very probably, as it has already happened in the 13 years between the last two important seismic events (Colfiorito 1997- L'Aquila 2009), there won't be enough time to solve all the problems connected to seismic risk: first of all the corruption related to politics concerning buildings; the lack of the money necessary to strengthen the already existing ones, historical centres, monuments and the masterpieces of Art; the difficult relations of the Institutions with the traditional media (newspapers, radio and TV) and, at the same time, the new media (web); the difficulties for scientists to reach important results in the immediate future due to the lack of funding and, last but not least, to the conflicting relationships inside the scientific community itself. In this scenario, communication and education play a crucial role in minimizing the risk of the population. In the present work we reconsider the past with the intent of starting to trace a path for a future strategy of risk communication where everybody involved, included the population, should do his best in order to face the next emergency.

  3. Biotelemetry data for golden eagles (Aquila chrysaetos) captured in coastal southern California, November 2014–February 2016

    USGS Publications Warehouse

    Tracey, Jeff A.; Madden, Melanie C.; Sebes, Jeremy B.; Bloom, Peter H.; Katzner, Todd Eli; Fisher, Robert N.

    2016-01-01

    The status of golden eagles (Aquila chrysaetos) in coastal southern California is unclear. To address this knowledge gap, the U.S. Geological Survey (USGS) in collaboration with local, State, and other Federal agencies began a multi-year survey and tracking program of golden eagles to address questions regarding habitat use, movement behavior, nest occupancy, genetic population structure, and human impacts on eagles. Golden eagle trapping and tracking efforts began in October 2014 and continued until early March 2015. During the first trapping season that focused on San Diego County, we captured 13 golden eagles (8 females and 5 males). During the second trapping season that began in November 2015, we focused on trapping sites in San Diego, Orange, and western Riverside Counties. By February 23, 2016, we captured an additional 14 golden eagles (7 females and 7 males). In this report, biotelemetry data were collected between November 22, 2014, and February 23, 2016. The location data for eagles ranged as far north as San Luis Obispo, California, and as far south as La Paz, Baja California, Mexico.

  4. Wing tucks are a response to atmospheric turbulence in the soaring flight of the steppe eagle Aquila nipalensis.

    PubMed

    Reynolds, Kate V; Thomas, Adrian L R; Taylor, Graham K

    2014-12-01

    Turbulent atmospheric conditions represent a challenge to stable flight in soaring birds, which are often seen to drop their wings in a transient motion that we call a tuck. Here, we investigate the mechanics, occurrence and causation of wing tucking in a captive steppe eagle Aquila nipalensis, using ground-based video and onboard inertial instrumentation. Statistical analysis of 2594 tucks, identified automatically from 45 flights, reveals that wing tucks occur more frequently under conditions of higher atmospheric turbulence. Furthermore, wing tucks are usually preceded by transient increases in airspeed, load factor and pitch rate, consistent with the bird encountering a headwind gust. The tuck itself immediately follows a rapid drop in angle of attack, caused by a downdraft or nose-down pitch motion, which produces a rapid drop in load factor. Positive aerodynamic loading acts to elevate the wings, and the resulting aerodynamic moment must therefore be balanced in soaring by an opposing musculoskeletal moment. Wing tucking presumably occurs when the reduction in the aerodynamic moment caused by a drop in load factor is not met by an equivalent reduction in the applied musculoskeletal moment. We conclude that wing tucks represent a gust response precipitated by a transient drop in aerodynamic loading. PMID:25320064

  5. Further Comment on “AGU Statement: Investigation of Scientists and Officials in L'Aquila, Italy, Is Unfounded”

    NASA Astrophysics Data System (ADS)

    Dobran, Flavio

    2010-10-01

    The AGU statement on the investigation of Italian scientists and officials in regard to the L'Aquila earthquake (Eos, 91(28), 248, 13 July 2010) appears to be a noble attempt to protect not only these individuals but also those AGU members who are involved in similar hazard and risk assessments. But in the long run this statement not only damages AGU by misleading its membership as to the responsibilities of the indicted individuals but also sends the wrong message to the Italian scientific communities about their social responsibilities. The AGU statement assumes that the indicted individuals are innocent because it is not possible for scientists to predict earthquakes, but it neglects to explain what their scientific responsibilities are and why these individuals may be also guilty of failing to properly exercise their social responsibility. If one accepts public funds, has the responsibility of deciding how to manage those funds, and is playing the double role of a scientist and a politician, one is also responsible for both the scientific and social consequences of one's actions. Because some of the indicted individuals are also responsible for drafting and promoting the unreliable Vesuvius Evacuation Plan (http://www.westnet.com/˜dobran), they should also be accountable for the consequences in the Vesuvius area.

  6. Gravity-driven postseismic deformation following the Mw 6.3 2009 L’Aquila (Italy) earthquake

    PubMed Central

    Albano, Matteo; Barba, Salvatore; Saroli, Michele; Moro, Marco; Malvarosa, Fabio; Costantini, Mario; Bignami, Christian; Stramondo, Salvatore

    2015-01-01

    The present work focuses on the postseismic deformation observed in the region of L’Aquila (central Italy) following the Mw 6.3 earthquake that occurred on April 6, 2009. A new, 16-month-long dataset of COSMO-SkyMed SAR images was analysed using the Persistent Scatterer Pairs interferometric technique. The analysis revealed the existence of postseismic ground subsidence in the mountainous rocky area of Mt Ocre ridge, contiguous to the sedimentary plain that experienced coseismic subsidence. The postseismic subsidence was characterized by displacements of 10 to 35 mm along the SAR line of sight. In the Mt Ocre ridge, widespread morphological elements associated with gravitational spreading have been previously mapped. We tested the hypothesis that the postseismic subsidence of the Mt Ocre ridge compensates the loss of equilibrium induced by the nearby coseismic subsidence. Therefore, we simulated the coseismic and postseismic displacement fields via the finite element method. We included the gravitational load and fault slip and accounted for the geometrical and rheological characteristics of the area. We found that the elastoplastic behaviour of the material under gravitational loading best explains the observed postseismic displacement. These findings emphasize the role of gravity in the postseismic processes at the fault scale. PMID:26553120

  7. Gravity-driven postseismic deformation following the Mw 6.3 2009 L’Aquila (Italy) earthquake

    NASA Astrophysics Data System (ADS)

    Albano, Matteo; Barba, Salvatore; Saroli, Michele; Moro, Marco; Malvarosa, Fabio; Costantini, Mario; Bignami, Christian; Stramondo, Salvatore

    2015-11-01

    The present work focuses on the postseismic deformation observed in the region of L’Aquila (central Italy) following the Mw 6.3 earthquake that occurred on April 6, 2009. A new, 16-month-long dataset of COSMO-SkyMed SAR images was analysed using the Persistent Scatterer Pairs interferometric technique. The analysis revealed the existence of postseismic ground subsidence in the mountainous rocky area of Mt Ocre ridge, contiguous to the sedimentary plain that experienced coseismic subsidence. The postseismic subsidence was characterized by displacements of 10 to 35 mm along the SAR line of sight. In the Mt Ocre ridge, widespread morphological elements associated with gravitational spreading have been previously mapped. We tested the hypothesis that the postseismic subsidence of the Mt Ocre ridge compensates the loss of equilibrium induced by the nearby coseismic subsidence. Therefore, we simulated the coseismic and postseismic displacement fields via the finite element method. We included the gravitational load and fault slip and accounted for the geometrical and rheological characteristics of the area. We found that the elastoplastic behaviour of the material under gravitational loading best explains the observed postseismic displacement. These findings emphasize the role of gravity in the postseismic processes at the fault scale.

  8. Gravity-driven postseismic deformation following the Mw 6.3 2009 L'Aquila (Italy) earthquake.

    PubMed

    Albano, Matteo; Barba, Salvatore; Saroli, Michele; Moro, Marco; Malvarosa, Fabio; Costantini, Mario; Bignami, Christian; Stramondo, Salvatore

    2015-01-01

    The present work focuses on the postseismic deformation observed in the region of L'Aquila (central Italy) following the Mw 6.3 earthquake that occurred on April 6, 2009. A new, 16-month-long dataset of COSMO-SkyMed SAR images was analysed using the Persistent Scatterer Pairs interferometric technique. The analysis revealed the existence of postseismic ground subsidence in the mountainous rocky area of Mt Ocre ridge, contiguous to the sedimentary plain that experienced coseismic subsidence. The postseismic subsidence was characterized by displacements of 10 to 35 mm along the SAR line of sight. In the Mt Ocre ridge, widespread morphological elements associated with gravitational spreading have been previously mapped. We tested the hypothesis that the postseismic subsidence of the Mt Ocre ridge compensates the loss of equilibrium induced by the nearby coseismic subsidence. Therefore, we simulated the coseismic and postseismic displacement fields via the finite element method. We included the gravitational load and fault slip and accounted for the geometrical and rheological characteristics of the area. We found that the elastoplastic behaviour of the material under gravitational loading best explains the observed postseismic displacement. These findings emphasize the role of gravity in the postseismic processes at the fault scale. PMID:26553120

  9. Estimation of occupancy, breeding success, and predicted abundance of golden eagles (Aquila chrysaetos) in the Diablo Range, California, 2014

    USGS Publications Warehouse

    Wiens, J. David; Kolar, Patrick S.; Fuller, Mark R.; Hunt, W. Grainger; Hunt, Teresa

    2015-01-01

    We used a multistate occupancy sampling design to estimate occupancy, breeding success, and abundance of territorial pairs of golden eagles (Aquila chrysaetos) in the Diablo Range, California, in 2014. This method uses the spatial pattern of detections and non-detections over repeated visits to survey sites to estimate probabilities of occupancy and successful reproduction while accounting for imperfect detection of golden eagles and their young during surveys. The estimated probability of detecting territorial pairs of golden eagles and their young was less than 1 and varied with time of the breeding season, as did the probability of correctly classifying a pair’s breeding status. Imperfect detection and breeding classification led to a sizeable difference between the uncorrected, naïve estimate of the proportion of occupied sites where successful reproduction was observed (0.20) and the model-based estimate (0.30). The analysis further indicated a relatively high overall probability of landscape occupancy by pairs of golden eagles (0.67, standard error = 0.06), but that areas with the greatest occupancy and reproductive potential were patchily distributed. We documented a total of 138 territorial pairs of golden eagles during surveys completed in the 2014 breeding season, which represented about one-half of the 280 pairs we estimated to occur in the broader 5,169-square kilometer region sampled. The study results emphasize the importance of accounting for imperfect detection and spatial heterogeneity in studies of site occupancy, breeding success, and abundance of golden eagles.

  10. Wing tucks are a response to atmospheric turbulence in the soaring flight of the steppe eagle Aquila nipalensis

    PubMed Central

    Reynolds, Kate V.; Thomas, Adrian L. R.; Taylor, Graham K.

    2014-01-01

    Turbulent atmospheric conditions represent a challenge to stable flight in soaring birds, which are often seen to drop their wings in a transient motion that we call a tuck. Here, we investigate the mechanics, occurrence and causation of wing tucking in a captive steppe eagle Aquila nipalensis, using ground-based video and onboard inertial instrumentation. Statistical analysis of 2594 tucks, identified automatically from 45 flights, reveals that wing tucks occur more frequently under conditions of higher atmospheric turbulence. Furthermore, wing tucks are usually preceded by transient increases in airspeed, load factor and pitch rate, consistent with the bird encountering a headwind gust. The tuck itself immediately follows a rapid drop in angle of attack, caused by a downdraft or nose-down pitch motion, which produces a rapid drop in load factor. Positive aerodynamic loading acts to elevate the wings, and the resulting aerodynamic moment must therefore be balanced in soaring by an opposing musculoskeletal moment. Wing tucking presumably occurs when the reduction in the aerodynamic moment caused by a drop in load factor is not met by an equivalent reduction in the applied musculoskeletal moment. We conclude that wing tucks represent a gust response precipitated by a transient drop in aerodynamic loading. PMID:25320064

  11. THE BLAST VIEW OF THE STAR-FORMING REGION IN AQUILA (l = 45{sup 0}, b = 0{sup 0})

    SciTech Connect

    Rivera-Ingraham, Alana; Martin, Peter G.; Netterfield, Calvin B.; Ade, Peter A. R.; Griffin, Matthew; Hargrave, Peter C.; Mauskopf, Philip; Bock, James J.; Chapin, Edward L.; Halpern, Mark; Marsden, Gaelen; Scott, Douglas; Devlin, Mark J.; Dicker, Simon R.; Klein, Jeff; Rex, Marie; Gundersen, Joshua O.; Hughes, David H.; Olmi, Luca; Patanchon, Guillaume

    2010-11-01

    We have carried out the first general submillimeter analysis of the field toward GRSMC 45.46+0.05, a massive star-forming region in Aquila. The deconvolved 6 deg{sup 2} (3{sup 0} x 2{sup 0}) maps provided by BLAST in 2005 at 250, 350, and 500 {mu}m were used to perform a preliminary characterization of the clump population previously investigated in the infrared, radio, and molecular maps. Interferometric CORNISH data at 4.8 GHz have also been used to characterize the Ultracompact H II regions (UCHIIRs) within the main clumps. By means of the BLAST maps, we have produced an initial census of the submillimeter structures that will be observed by Herschel, several of which are known Infrared Dark Clouds. Our spectral energy distributions of the main clumps in the field, located at {approx}7 kpc, reveal an active population with temperatures of T{approx} 35-40 K and masses of {approx}10{sup 3} M{sub sun} for a dust emissivity index {beta} = 1.5. The clump evolutionary stages range from evolved sources, with extended H II regions and prominent IR stellar population, to massive young stellar objects, prior to the formation of an UCHIIR. The CORNISH data have revealed the details of the stellar content and structure of the UCHIIRs. In most cases, the ionizing stars corresponding to the brightest radio detections are capable of accounting for the clump bolometric luminosity, in most cases powered by embedded OB stellar clusters.

  12. Broadband X-ray spectra of the ultraluminous X-ray source Holmberg IX X-1 observed with NuSTAR, XMM-Newton, and Suzaku

    SciTech Connect

    Walton, D. J.; Harrison, F. A.; Grefenstette, B. W.; Fuerst, F.; Madsen, K. K.; Rana, V.; Stern, D.; Miller, J. M.; Bachetti, M.; Barret, D.; Webb, N.; Boggs, S. E.; Craig, W. W.; Christensen, F. E.; Fabian, A. C.; Parker, M. L.; Hailey, C. J.; Ptak, A.; Zhang, W. W.

    2014-09-20

    We present results from the coordinated broadband X-ray observations of the extreme ultraluminous X-ray source Holmberg IX X-1 performed by NuSTAR, XMM-Newton, and Suzaku in late 2012. These observations provide the first high-quality spectra of Holmberg IX X-1 above 10 keV to date, extending the X-ray coverage of this remarkable source up to ∼30 keV. Broadband observations were undertaken at two epochs, between which Holmberg IX X-1 exhibited both flux and strong spectral variability, increasing in luminosity from L {sub X} = (1.90 ± 0.03) × 10{sup 40} erg s{sup –1} to L {sub X} = (3.35 ± 0.03) × 10{sup 40} erg s{sup –1}. Neither epoch exhibits a spectrum consistent with emission from the standard low/hard accretion state seen in Galactic black hole binaries, which would have been expected if Holmberg IX X-1 harbors a truly massive black hole accreting at substantially sub-Eddington accretion rates. The NuSTAR data confirm that the curvature observed previously in the 3-10 keV bandpass does represent a true spectral cutoff. During each epoch, the spectrum appears to be dominated by two optically thick thermal components, likely associated with an accretion disk. The spectrum also shows some evidence for a nonthermal tail at the highest energies, which may further support this scenario. The available data allow for either of the two thermal components to dominate the spectral evolution, although both scenarios require highly nonstandard behavior for thermal accretion disk emission.

  13. Sco X-1 - A galactic radio source with an extragalactic radio morphology

    NASA Technical Reports Server (NTRS)

    Geldzahler, B. J.; Corey, B. E.; Fomalont, E. B.; Hilldrup, K.

    1981-01-01

    VLA observations of radio emissions at 1465 and 4885 MHz, of Sco X-1 confirm the existence of a colinear triple structure. Evidence that the three components of Sco X-1 are physically associated is presented, including the morphology, spectrum, variability, volume emissivity and magnetic field strength. The possibility of a physical phenomenon occurring in Sco X-1 similar to that occurring in extragalactic radio sources is discussed, and two galactic sources are found having extended emission similar to that in extragalactic objects. The extended structure of Sco X-1 is also observed to be similar to that of the hot spots in luminous extragalactic sources, and a radio source 20 arcmin from Sco X-1 is found to lie nearly along the radio axis formed by the components of Sco X-1.

  14. Microfluidic binary phase flow

    NASA Astrophysics Data System (ADS)

    Angelescu, Dan; Menetrier, Laure; Wong, Joyce; Tabeling, Patrick; Salamitou, Philippe

    2004-03-01

    We present a novel binary phase flow regime where the two phases differ substantially in both their wetting and viscous properties. Optical tracking particles are used in order to investigate the details of such multiphase flow inside capillary channels. We also describe microfluidic filters we have developed, capable of separating the two phases based on capillary pressure. The performance of the filters in separating oil-water emulsions is discussed. Binary phase flow has been previously used in microchannels in applications such as emulsion generation, enhancement of mixing and assembly of custom colloidal paticles. Such microfluidic systems are increasingly used in a number of applications spanning a diverse range of industries, such as biotech, pharmaceuticals and more recently the oil industry.

  15. Binary Love relations

    NASA Astrophysics Data System (ADS)

    Yagi, Kent; Yunes, Nicolás

    2016-07-01

    When in a tight binary, the mutual tidal deformations of neutron stars get imprinted onto observables, encoding information about their internal structure at supranuclear densities and gravity in the extreme-gravity regime. Gravitational wave (GW) observations of their late binary inspiral may serve as a tool to extract the individual tidal deformabilities, but this is made difficult by degeneracies between them in the GW model. We here resolve this problem by discovering approximately equation-of-state (EoS)-insensitive relations between dimensionless combinations of the individual tidal deformabilities. We show that these relations break degeneracies in the GW model, allowing for the accurate extraction of both deformabilities. Such measurements can be used to better differentiate between EoS models, and improve tests of general relativity and cosmology.

  16. Molecular analysis of PinX1 in human hepatocellular carcinoma.

    PubMed

    Oh, Bong-Kyeong; Chae, Kwang Jo; Park, Chanil; Park, Young Nyun

    2004-10-01

    PinX1 is located at 8p23, a region with frequent loss of heterozygosity in hepatocellular carcinomas (HCCs). Overexpression of PinX1 is known to inhibit telomerase activity, shorten telomeres and induce crisis while its depletion increases tumorigenesis in nude mice. These results suggest that PinX1 might be critical for hepatocarcinogenesis. In this study, we assessed transcript expression of PinX1, the correlation between PinX1 mRNA level and telomere length and telomerase activity, as well as sequence alteration, in 24 HCCs and their adjacent non-HCC tissues from patients with B viral chronic hepatitis/cirrhosis. There was no significant difference between the levels of PinX1 mRNA in HCCs and those in non-HCCs. The PinX1 mRNA tended to increase as the telomere shortened in the HCCs (p=0.067, R(2)=0.166), but no correlation was found in non-HCCs. The PinX1 level revealed no significant relationship with telomerase activity in HCCs and non-HCCs. The missense mutations of PinX1, at the 254 and 265 residues, were found in 17% of the HCCs and their adjacent non-HCCs. The mutations were located in the non-conserved region and revealed no relation with PinX1 expression, telomere length and telomerase activity, suggesting that they are likely polymorphisms. Our findings suggest that PinX1 may not play a major role in hepatocarcinogenesis as a target tumor suppressor gene. PinX1, however, might be involved in the telomere length regulation of HCCs. PMID:15375513

  17. Binary Optics Toolkit

    Energy Science and Technology Software Center (ESTSC)

    1996-04-02

    This software is a set of tools for the design and analysis of binary optics. It consists of a series of stand-alone programs written in C and some scripts written in an application-specific language interpreted by a CAD program called DW2000. This software can be used to optimize the design and placement of a complex lens array from input to output and produce contours, mask designs, and data exported for diffractive optic analysis.

  18. Parametric binary dissection

    NASA Technical Reports Server (NTRS)

    Bokhari, Shahid H.; Crockett, Thomas W.; Nicol, David M.

    1993-01-01

    Binary dissection is widely used to partition non-uniform domains over parallel computers. This algorithm does not consider the perimeter, surface area, or aspect ratio of the regions being generated and can yield decompositions that have poor communication to computation ratio. Parametric Binary Dissection (PBD) is a new algorithm in which each cut is chosen to minimize load + lambda x(shape). In a 2 (or 3) dimensional problem, load is the amount of computation to be performed in a subregion and shape could refer to the perimeter (respectively surface) of that subregion. Shape is a measure of communication overhead and the parameter permits us to trade off load imbalance against communication overhead. When A is zero, the algorithm reduces to plain binary dissection. This algorithm can be used to partition graphs embedded in 2 or 3-d. Load is the number of nodes in a subregion, shape the number of edges that leave that subregion, and lambda the ratio of time to communicate over an edge to the time to compute at a node. An algorithm is presented that finds the depth d parametric dissection of an embedded graph with n vertices and e edges in O(max(n log n, de)) time, which is an improvement over the O(dn log n) time of plain binary dissection. Parallel versions of this algorithm are also presented; the best of these requires O((n/p) log(sup 3)p) time on a p processor hypercube, assuming graphs of bounded degree. How PBD is applied to 3-d unstructured meshes and yields partitions that are better than those obtained by plain dissection is described. Its application to the color image quantization problem is also discussed, in which samples in a high-resolution color space are mapped onto a lower resolution space in a way that minimizes the color error.

  19. Evolutionary models of binaries

    NASA Astrophysics Data System (ADS)

    van Rensbergen, Walter; Mennekens, Nicki; de Greve, Jean-Pierre; Jansen, Kim; de Loore, Bert

    2011-07-01

    We have put on CDS a catalog containing 561 evolutionary models of binaries: J/A+A/487/1129 (Van Rensbergen+, 2008). The catalog covers a grid of binaries with a B-type primary at birth, different values for the initial mass ratio and a wide range of initial orbital periods. The evolution was calculated with the Brussels code in which we introduced the spinning up and the creation of a hot spot on the gainer or its accretion disk, caused by impacting mass coming from the donor. When the kinetic energy of fast rotation added to the radiative energy of the hot spot exceeds the binding energy, a fraction of the transferred matter leaves the system: the evolution is liberal during a short lasting era of rapid mass transfer. The spin-up of the gainer was modulated using both strong and weak tides. The catalog shows the results for both types. For comparison, we included the evolutionary tracks calculated with the conservative assumption. Binaries with an initial primary below 6 Msolar show hardly any mass loss from the system and thus evolve conservatively. Above this limit differences between liberal and conservative evolution grow with increasing initial mass of the primary star.

  20. Accretion Disk Dynamics in X-Ray Binaries

    NASA Astrophysics Data System (ADS)

    Schulz, Norbert S.; Ji, Li; Nowak, M.; Canizares, C. R.; Kallman, T.

    2009-09-01

    The last decade of X-ray observations was an era of true discovery in the study of accretion phenomena in X-ray binaries. With the launch of high resolution X-ray spectrometers on board the Chandra X-ray Observatory and XMM Newton we gained novel insights in feedback processes in accretion disks. At the forefront are dynamics in winds and outflows. Recent observations now also not only reveal properties of accretion disk coronal phenomena but point us to highly variable activity in their appearance. Amongst others these include heating along the spectral branches in the Z-source Cyg X-2, short and longterm variations in the photo-ionized emissions in Cir X-1, highly variable and dynamic Ne edges in the ultra-compact binary 4U 0614+091. This presentation summarizes these recent developments and provides an outlook towards more dynamical accretion disk coronal models and perspectives for future missions.

  1. Binary-Signal Recovery

    NASA Technical Reports Server (NTRS)

    Griebeler, Elmer L.

    2011-01-01

    Binary communication through long cables, opto-isolators, isolating transformers, or repeaters can become distorted in characteristic ways. The usual solution is to slow the communication rate, change to a different method, or improve the communication media. It would help if the characteristic distortions could be accommodated at the receiving end to ease the communication problem. The distortions come from loss of the high-frequency content, which adds slopes to the transitions from ones to zeroes and zeroes to ones. This weakens the definition of the ones and zeroes in the time domain. The other major distortion is the reduction of low frequency, which causes the voltage that defines the ones or zeroes to drift out of recognizable range. This development describes a method for recovering a binary data stream from a signal that has been subjected to a loss of both higher-frequency content and low-frequency content that is essential to define the difference between ones and zeroes. The method makes use of the frequency structure of the waveform created by the data stream, and then enhances the characteristics related to the data to reconstruct the binary switching pattern. A major issue is simplicity. The approach taken here is to take the first derivative of the signal and then feed it to a hysteresis switch. This is equivalent in practice to using a non-resonant band pass filter feeding a Schmitt trigger. Obviously, the derivative signal needs to be offset to halfway between the thresholds of the hysteresis switch, and amplified so that the derivatives reliably exceed the thresholds. A transition from a zero to a one is the most substantial, fastest plus movement of voltage, and therefore will create the largest plus first derivative pulse. Since the quiet state of the derivative is sitting between the hysteresis thresholds, the plus pulse exceeds the plus threshold, switching the hysteresis switch plus, which re-establishes the data zero to one transition

  2. Hydrothermal anomalies before the 2009 Mw 6.3 L'Aquila earthquake in Italy referring to the geospheres coupling effects

    NASA Astrophysics Data System (ADS)

    Wu, Lixin; Zheng, Shuo; Qin, Kai; De Santis, Angelo; Liu, Shanjun

    2016-04-01

    A large number of precursory anomalies of the 2009 L'Aquila EQ were reported after the shocking, including thermal properties, electric and magnetic fields, gas emissions and seismicity. Previous studies on the seismic b-value are also insufficient, which is possibly a proxy of crust stress conditions and could therewith act as a crude stress-meter wherever seismicity is observed in lithosphere. Nevertheless, the reported anomalies have not been so far synergically analyzed to interpret or prove the potential coupling process among different geospheres. In this paper, the spatio-temporal evolution of several hydrothermal parameters related to the coversphere and atmosphere, including soil moisture, soil temperature, near-surface air temperature, and precipitable water, was comprehensively investigated. Air temperature and atmospheric aerosol were also statistically analyzed in time series with ground observations. An abnormal enhancement of aerosol occurred on March 30, 2009 and thus proved quasi-synchronous anomalies among the hydrothermal parameters from March 29 to 31 in particular places geo-related to tectonic thrusts and local topography. In additional, the three-dimensional (3D) visualization analysis of b-value revealed that regional stress accumulated to a high level, particularly in the L'Aquila basin and around regional large thrusts. This links logically and spatially the multiple observations on coversphere and atmosphere with that on lithosphere. Finally, the coupling effects of geospheres were discussed, and a conceptual LCA coupling mode was proposed to interpret the possible mechanisms of the multiple quasi-synchronous anomalies preceding the L'Aquila EQ. Results indicate that CO2-rich fluids in deep crust might have played a significant role in the local LCA coupling process.

  3. Ground motions recorded in Rome during the April 2009 L’Aquila seismic sequence: site response and comparison with ground‐motion predictions based on a global dataset

    USGS Publications Warehouse

    Caserta, Arrigo; Boore, David; Rovelli, Antonio; Govoni, Aladino; Marra, Fabrizio; Monica, Gieseppe Della; Boschi, Enzo

    2013-01-01

    The mainshock and moderate‐magnitude aftershocks of the 6 April 2009 M 6.3 L’Aquila seismic sequence, about 90 km northeast of Rome, provided the first earthquake ground‐motion recordings in the urban area of Rome. Before those recordings were obtained, the assessments of the seismic hazard in Rome were based on intensity observations and theoretical considerations. The L’Aquila recordings offer an unprecedented opportunity to calibrate the city response to central Apennine earthquakes—earthquakes that have been responsible for the largest damage to Rome in historical times. Using the data recorded in Rome in April 2009, we show that (1) published theoretical predictions of a 1 s resonance in the Tiber valley are confirmed by observations showing a significant amplitude increase in response spectra at that period, (2) the empirical soil‐transfer functions inferred from spectral ratios are satisfactorily fit through 1D models using the available geological, geophysical, and laboratory data, but local variability can be large for individual events, (3) response spectra for the motions recorded in Rome from the L’Aquila earthquakes are significantly amplified in the radial component at periods near 1 s, even at a firm site on volcanic rocks, and (4) short‐period response spectra are smaller than expected when compared to ground‐motion predictions from equations based on a global dataset, whereas the observed response spectra are higher than expected for periods near 1 s.

  4. Pediatric Epidemic of Salmonella enterica Serovar Typhimurium in the Area of L’Aquila, Italy, Four Years after a Catastrophic Earthquake

    PubMed Central

    Nigro, Giovanni; Bottone, Gabriella; Maiorani, Daniela; Trombatore, Fabiana; Falasca, Silvana; Bruno, Gianfranco

    2016-01-01

    Background: A Salmonella enterica epidemic occurred in children of the area of L’Aquila (Central Italy, Abruzzo region) between June 2013 and October 2014, four years after the catastrophic earthquake of 6 April 2009. Methods: Clinical and laboratory data were collected from hospitalized and ambulatory children. Routine investigations for Salmonella infection were carried out on numerous alimentary matrices of animal origin and sampling sources for drinking water of the L’Aquila district, including pickup points of the two main aqueducts. Results: Salmonella infection occurred in 155 children (83 females: 53%), aged 1 to 15 years (mean 2.10). Of these, 44 children (28.4%) were hospitalized because of severe dehydration, electrolyte abnormalities, and fever resistant to oral antipyretic and antibiotic drugs. Three children (1.9%) were reinfected within four months after primary infection by the same Salmonella strain. Four children (2.6%), aged one to two years, were coinfected by rotavirus. A seven-year old child had a concomitant right hip joint arthritis. The isolated strains, as confirmed in about the half of cases or probable/possible in the remaining ones, were identified as S. enterica serovar Typhimurium [4,5:i:-], monophasic variant. Aterno river, bordering the L’Aquila district, was recognized as the main responsible source for the contamination of local crops and vegetables derived from polluted crops. Conclusions: The high rate of hospitalized children underlines the emergence of a highly pathogenic S. enterica strain probably subsequent to the contamination of the spring water sources after geological changes occurred during the catastrophic earthquake. PMID:27164121

  5. Analysis of optical spectra of V1357 Cyg≡Cyg X-1

    NASA Astrophysics Data System (ADS)

    Shimanskii, V. V.; Karitskaya, E. A.; Bochkarev, N. G.; Galazutdinov, G. A.; Lyuty, V. M.; Shimanskaya, N. N.

    2012-10-01

    Optical spectra and light curves of the massive X-ray binary V1357 Cyg are analyzed. The calculations were based on models of irradiated plane-parallel stellar atmospheres, taking into account reflection of the X-ray radiation, asphericity of the stellar surface, and deviations from LTE for several ions. Comparison of observed spectra obtained in 2004-2005 at the Bohyunsan Observatory (South Korea) revealed variations of the depths of HI lines by up to 18% and of HeI and heavy elements lines by up to 10%. These variations are not related to the orbital motion of the star, and are probably due to variations of the stellar wind intensity. Perturbations of the thermal structure of the atmosphere due to irradiation in various states of Cyg X-1 (including outburst) do not lead to the formation of a hot photosphere with an electron temperature exceeding the effective temperature. As a result, variations of the profiles of optical lines of HI, HeI, and heavy elements due to the orbital motion of the star and variations of the irradiating X-ray flux do not exceed 1% of the residual intensities. Allowing for deviations from LTE enhances the HI and HeI lines by factors of two to three and the MgII lines by a factor of nine, and is therefore required for a fully adequate analysis of the observational data. Analysis of the HI, HeI, and HeII lines profiles yielded the following set of parameters for theOstar at the observing epoch: T eff = 30 500±500 K, log g = 3.31 ±0.05, [He/H] = 0.42 ± 0.05. The observed HeI line profiles have emission components that are formed in the stellar wind and increase with the line intensity. The abundances of 11 elements in the atmospheres of V1357 Cyg and α Cam, which has a similar spectral type and luminosity class, are derived. The chemical composition of V1357 Cyg is characterized by a strong excess of helium, nitrogen, neon, and silicon, which is related to the binarity of the system.

  6. April 7, 2009, Mw 5.5 aftershock of the L'Aquila earthquake: seismogenic fault geometry and its implication for the central Apennines active extensional tectonics (Italy).

    NASA Astrophysics Data System (ADS)

    Adinolfi, Guido Maria; Lavecchia, Giusy; De Matteis, Raffaella; Nardis Rita, De; Francesco, Brozzetti; Federica, Ferrarini; Zollo, Aldo

    2015-04-01

    On April 6, 2009 (at 01:32 UTC) a Mw 6.3 earthquake hit the town of L'Aquila (central Italy) and surrounding villages causing fatalities and severe damage in the area. After few days, a nearly 40-km-long extensional fault system was activated generating both northward and southward seismicity migration along the NW-SE trending sector of central Apennines. During the intense aftershocks sequence, different sesmogenic sources with a distinct geometry, size and the degree of involvement were reactivated. Among the relevant aftershocks with Mw 5.0 to 5.5, the largest one occurred on April 7 (at 17:47 UTC), 9 km SE-ward of the mainshock involving a source seated at much greater depths (~14 km). Despite the enormous number of studies of the 2009 L'Aquila earthquake, mainly focused on the various geological and seismological aspects of the main Paganica source, the April 7 strongest aftershock (Mw 5.5) has not yet been deeply investigated. Consistent geometric and kinematic correlations between the geological and seismological data about this seismogenic source are missing. There are still open questions concerning its unresolved geometry and the unknown style of the central Apennines structure activated at greater depths during the 2009 L'Aquila seismic sequence. Furthermore, some authors (Lavecchia et al., 2012) have supposed that the April 7, 2009 aftershock (Mw 5.5) occurred onto an high dip segment (~50°) of an east-dipping extensional basal detachment with a potential surface expression outcropping in the area of the eastern Sabina-Simbruini Mts. In this work we propose a seismological analysis of the April 7, 2009 aftershock (Mw 5.5) rupture process. In order to define the unresolved source geometry, we computed the focal mechanism through the time domain, moment tensor full waveform inversion (Dreger and Helmberger, 1993). Also, we estimated the apparent source time functions (ASTFs) by deconvolution of the impulse response of the medium from the recorded data

  7. News and Views: L'Aquila verdict poses risk for science; HARPS spots nearby exo-Earth Citizen science finds planet

    NASA Astrophysics Data System (ADS)

    2012-12-01

    The conviction of six Italian seismologists for manslaughter following the L'Aquila earthquake has been met with concern by scientific bodies around the world. European astronomers have found a planet with about the mass of the Earth orbiting a star in the Alpha Centauri system. The planet, the lightest exoplanet discovered around a star like the Sun, was detected using the HARPS instrument on the 3.6 m telescope at ESO's La Silla Observatory in Chile. The citizen science project Planet Hunters has discovered the first planet found in a four-star system.

  8. OPTICAL PROPERTIES OF THE ULTRALUMINOUS X-RAY SOURCE HOLMBERG IX X-1 AND ITS STELLAR ENVIRONMENT

    SciTech Connect

    Grise, F.; Kaaret, P.; Pakull, M. W.; Motch, C.

    2011-06-10

    Holmberg IX X-1 is an archetypal ultraluminous X-ray source (ULX). Here we study the properties of the optical counterpart and of its stellar environment using optical data from SUBARU/Faint Object Camera and Spectrograph, GEMINI/GMOS-N and Hubble Space Telescope (HST)/Advanced Camera for Surveys, as well as simultaneous Chandra X-ray data. The V {approx} 22.6 spectroscopically identified optical counterpart is part of a loose cluster with an age {approx}< 20 Myr. Consequently, the mass upper limit on individual stars in the association is about 20 M{sub sun}. The counterpart is more luminous than the other stars of the association, suggesting a non-negligible optical contribution from the accretion disk. An observed UV excess also points to non-stellar light similar to X-ray active low-mass X-ray binaries. A broad He II {lambda}4686 emission line identified in the optical spectrum of the ULX further suggests optical light from X-ray reprocessing in the accretion disk. Using stellar evolutionary tracks, we have constrained the mass of the counterpart to be {approx}> 10 M{sub sun}, even if the accretion disk contributes significantly to the optical luminosity. Comparison of the photometric properties of the counterpart with binary models show that the donor may be more massive, {approx}> 25 M{sub sun}, with the ULX system likely undergoing case AB mass transfer. Finally, the counterpart exhibits photometric variability of 0.14 mag between two HST observations separated by 50 days which could be due to ellipsoidal variations and/or disk reprocessing of variable X-ray emission.

  9. Binary optics: Trends and limitations

    NASA Technical Reports Server (NTRS)

    Farn, Michael W.; Veldkamp, Wilfrid B.

    1993-01-01

    We describe the current state of binary optics, addressing both the technology and the industry (i.e., marketplace). With respect to the technology, the two dominant aspects are optical design methods and fabrication capabilities, with the optical design problem being limited by human innovation in the search for new applications and the fabrication issue being limited by the availability of resources required to improve fabrication capabilities. With respect to the industry, the current marketplace does not favor binary optics as a separate product line and so we expect that companies whose primary purpose is the production of binary optics will not represent the bulk of binary optics production. Rather, binary optics' more natural role is as an enabling technology - a technology which will directly result in a competitive advantage in a company's other business areas - and so we expect that the majority of binary optics will be produced for internal use.

  10. A census of dense cores in the Aquila cloud complex: SPIRE/PACS observations from the Herschel Gould Belt survey

    NASA Astrophysics Data System (ADS)

    Könyves, V.; André, Ph.; Men'shchikov, A.; Palmeirim, P.; Arzoumanian, D.; Schneider, N.; Roy, A.; Didelon, P.; Maury, A.; Shimajiri, Y.; Di Francesco, J.; Bontemps, S.; Peretto, N.; Benedettini, M.; Bernard, J.-Ph.; Elia, D.; Griffin, M. J.; Hill, T.; Kirk, J.; Ladjelate, B.; Marsh, K.; Martin, P. G.; Motte, F.; Nguyên Luong, Q.; Pezzuto, S.; Roussel, H.; Rygl, K. L. J.; Sadavoy, S. I.; Schisano, E.; Spinoglio, L.; Ward-Thompson, D.; White, G. J.

    2015-12-01

    We present and discuss the results of the Herschel Gould Belt survey (HGBS) observations in an 11 deg2 area of the Aquila molecular cloud complex at d 260 pc, imaged with the SPIRE and PACS photometric cameras in parallel mode from 70 μm to 500 μm. Using the multi-scale, multi-wavelength source extraction algorithm getsources, we identify a complete sample of starless dense cores and embedded (Class 0-I) protostars in this region, and analyze their global properties and spatial distributions. We find a total of 651 starless cores, 60% ± 10% of which are gravitationally bound prestellar cores, and they will likely form stars inthe future. We also detect 58 protostellar cores. The core mass function (CMF) derived for the large population of prestellar cores is very similar in shape to the stellar initial mass function (IMF), confirming earlier findings on a much stronger statistical basis and supporting the view that there is a close physical link between the stellar IMF and the prestellar CMF. The global shift in mass scale observed between the CMF and the IMF is consistent with a typical star formation efficiency of 40% at the level of an individual core. By comparing the numbers of starless cores in various density bins to the number of young stellar objects (YSOs), we estimate that the lifetime of prestellar cores is 1 Myr, which is typically 4 times longer than the core free-fall time, and that it decreases with average core density. We find a strong correlation between the spatial distribution of prestellar cores and the densest filaments observed in the Aquila complex. About 90% of the Herschel-identified prestellar cores are located above a background column density corresponding to AV 7, and 75% of them lie within filamentary structures with supercritical masses per unit length ≳16 M⊙/pc. These findings support a picture wherein the cores making up the peak of the CMF (and probably responsible for the base of the IMF) result primarily from the

  11. The Search for Trojan Binaries

    NASA Astrophysics Data System (ADS)

    Merline, William J.; Tamblyn, P. M.; Dumas, C.; Close, L. M.; Chapman, C. R.; Durda, D. D.; Levison, H. F.; Hamilton, D. P.; Nesvorny, D.; Storrs, A.; Enke, B.; Menard, F.

    2007-10-01

    We report on observations of Jupiter Trojan asteroids in search of binaries. We made observations using HST/ACS of 35 small (V = 17.5-19.5) objects in Cycle 14, without detecting any binaires. We have also observed a few dozen Trojans in our ground-based study of larger Trojans, discovering only one binary. The result is that the frequency of moderately-separated binaries among the Trojans seem rather low, likely less than 5%. Although we have only statistics of small numbers, it appears that the binary frequencies are more akin to the larger Main-Belt asteroids, than to the frequency in the TNO region, which probably exceeds 10%. The low frequency is inconsistent with the projections based on Trojan contact binaries by Mann et al. (2006, BAAS 38, 6509), although our work cannot detect very close or contact binaries. We discovered and characterized the orbit and density of the first Trojan binary, (617) Patroclus using the Gemini AO system (Merline et al. 2001 IAUC 7741). A second binary, (624) Hecktor, has now been reported by Marchis et al. (2006, IAUC 8732). In a broad survey of Main Belt asteroids, we found that, among the larger objects, the binary fraction is about 2%, while we are finding that the fraction is significantly higher among smaller asteroids (and this is even more apparent from lightcurve discoveries). Further, characteristics of these smaller systems indicate a distinctly different formation mechanism the the larger MB binaries. Because the Trojans have compositions that are more like the KBOs, while they live in a collisional environment much more like the Main Belt than the KBOs, these objects should hold vital clues to binary formation mechanics. And because there seems to be a distinct difference in larger and smaller main-belt binaries, we sought to detect such differences among the Trojans as well.

  12. [Sleep disturbances and spatial memory deficits in post-traumatic stress disorder: the case of L'Aquila (Central Italy)].

    PubMed

    Ferrara, Michele; Mazza, Monica; Curcio, Giuseppe; Iaria, Giuseppe; De Gennaro, Luigi; Tempesta, Daniela

    2016-01-01

    Altered sleep is a common and central symptom of post-traumatic stress disorder (PTSD). In fact, sleep disturbances are included in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) diagnostic criteria for PTSD. However, it has been hypothesized that sleep disturbances are crucially involved in the aetiology of PTSD, rather than being solely a symptom arising secondarily from this disorder. Therefore, knowing the long-term effects of a trauma can be essential to establish the need of specific interventions for the prevention and treatment of mental disorders that may persist years after a traumatic experience. In one study we showed, for the first time, that even after a period of two years people exposed to a catastrophic disaster such as the L'Aquila earthquake continue to suffer from a reduced sleep quality. Moreover, we observed that sleep quality scores decreased as a function of the proximity to the epicentre, suggesting that the psychological effects of an earthquake may be pervasive and long-lasting. It has been widely shown that disruption of sleep by acute stress may lead to deterioration in memory processing. In fact, in a recent study we observed alterations in spatial memory in PTSD subjects. Our findings indicated that PTSD is accompanied by an impressive deficit in forming a cognitive map of the environment, as well as in sleep-dependent memory consolidation. The fact that this deterioration was correlated to the subjective sleep disturbances in our PTSD group demonstrates the existence of an intimate relationship between sleep, memory consolidation, and stress. PMID:27291208

  13. Complexity of the Mw 6.3 2009 L'Aquila (central Italy) earthquake: 2. Broadband strong motion modeling

    NASA Astrophysics Data System (ADS)

    Ameri, G.; Gallovič, F.; Pacor, F.

    2012-04-01

    Near-fault strong-ground motions (0.1-10 Hz) recorded during the Mw 6.3 2009 L'Aquila earthquake exhibit great spatial variability. Modeling the observed seismograms allows linking distinct features of the observed wavefield to particular source and propagation effects and provides insights on strong motion complexity from this moderate magnitude event. We utilize a hybrid integral-composite approach based on a k-square kinematic rupture model, combining low-frequency coherent and high-frequency incoherent source radiation and providing omega-squared source spectral decay. Several source model features, proven to be stable by means of an uncertainty analysis in the preceding low-frequency (<0.2 Hz) multiple finite-extent source inversion (Paper 1), were constrained. Synthetic Green's functions are calculated in a 1D-layered crustal model including 1D soil profiles to account for site-specific response (where available). The results show that although the local site effects improve the modeling, the spatial broadband ground-motion variability is to large extent controlled by the rupture kinematics. The modeling thus confirms and further constraints the source model features, including the position and slip amount of the two main asperities, the largest asperity time delay and the rupture velocity distribution on the fault. Furthermore, we demonstrate that the crossover frequency dividing the coherent and incoherent wavefield, often considered independent on the station position, has to be variable in order to adequately reproduce both near and far station recordings. This suggests that the incoherency of the radiated wavefield is controlled by the wave-propagation phenomena and/or the initial updip rupture propagation was very smooth (coherent) up to relatively high frequencies (>2 Hz).

  14. Long-term blood pressure changes induced by the 2009 L'Aquila earthquake: assessment by 24 h ambulatory monitoring.

    PubMed

    Giorgini, Paolo; Striuli, Rinaldo; Petrarca, Marco; Petrazzi, Luisa; Pasqualetti, Paolo; Properzi, Giuliana; Desideri, Giovambattista; Omboni, Stefano; Parati, Gianfranco; Ferri, Claudio

    2013-09-01

    An increased rate of cardiovascular and cerebrovascular events has been described during and immediately after earthquakes. In this regard, few data are available on long-term blood pressure control in hypertensive outpatients after an earthquake. We evaluated the long-term effects of the April 2009 L'Aquila earthquake on blood pressure levels, as detected by 24 h ambulatory blood pressure monitoring. Before/after (mean±s.d. 6.9±4.5/14.2±5.1 months, respectively) the earthquake, the available 24 h ambulatory blood pressure monitoring data for the same patients were extracted from our database. Quake-related daily life discomforts were evaluated through interviews. We enrolled 47 patients (25 female, age 52±14 years), divided into three groups according to antihypertensive therapy changes after versus before the earthquake: unchanged therapy (n=24), increased therapy (n=17) and reduced therapy (n=6). Compared with before the quake, in the unchanged therapy group marked increases in 24 h (P=0.004), daytime (P=0.01) and nighttime (P=0.02) systolic blood pressure were observed after the quake. Corresponding changes in 24 h (P=0.005), daytime (P=0.01) and nighttime (P=0.009) diastolic blood pressure were observed. Daily life discomforts were reported more frequently in the unchanged therapy and increased therapy groups than the reduced therapy group (P=0.025 and P=0.018, respectively). In conclusion, this study shows that patients with unchanged therapy display marked blood pressure increments up to more than 1 year after an earthquake, as well as long-term quake-related discomfort. Our data suggest that particular attention to blood pressure levels and adequate therapy modifications should be considered after an earthquake, not only early after the event but also months later. PMID:23595046

  15. The preparatory phase of the April 6th 2009, Mw 6.3, L’Aquila earthquake: Seismological observations

    NASA Astrophysics Data System (ADS)

    Lucente, F. P.; de Gori, P.; Margheriti, L.; Piccinini, D.; Dibona, M.; Chiarabba, C.; Piana Agostinetti, N.

    2009-12-01

    Few decades ago, the dilatancy-diffusion hypothesis held great promise as a physical basis for developing earthquakes prediction techniques, but the potential never become reality, as the result of too few observations consistent with the theory. One of the main problems has been the lack of detailed monitoring records of small earthquakes swarms spatio-temporally close to the incoming major earthquakes. In fact, the recognition of dilatancy-related effects requires the use of very dense network of three-component seismographs, which, in turn, implies the a-priori knowledge of major earthquakes location, i.e., actually a paradox. The deterministic prediction of earthquakes remains a long time, hard task to accomplish. Nevertheless, for seismologists, the understanding of the processes that preside over the earthquakes nucleation and the mechanics of faulting represents a big step toward the ability to predict earthquakes. Here we describe a set of seismological observations done on the foreshock sequence that preceded the April 6th 2009, Mw 6.3, L’Aquila earthquake. In this occasion, the dense configuration of the seismic network in the area gave us the unique opportunity for a detailed reconstruction of the preparatory phase of the main shock. We show that measurable precursory effects, as changes of the seismic waves velocity and of the anisotropic parameters in the crust, occurred before the main shock. From our observations we infer that fluids play a key role in the fault failure process, and, most significantly, that the elastic properties of the rock volume surrounding the main shock nucleation area undergo a dramatic change about a week before the main shock occurrence.

  16. The 2009 L'Aquila earthquake sequence: technical and scientific activities during the emergency and post-emergency phases

    NASA Astrophysics Data System (ADS)

    Cardinali, Mauro

    2010-05-01

    The Central Apennines of Italy is an area characterized by significant seismic activity. In this area, individual earthquakes and prolonged seismic sequences produce a variety of ground effects, including landslides. The L'Aquila area, in the Abruzzo Region, was affected by an earthquake sequence that started on December 2008, and continued for several months. The main shock occurred on April 6, 2009, with local magnitude m = 6.3, and was followed by two separate earthquakes on April 7 and April 9, each with a local magnitude m > 5.0. The main shocks caused 308 fatalities, injured more than 1500 people, and left in excess of 65,000 people homeless. Damage to the cultural heritage was also severe, with tens of churches and historical buildings severely damaged or destroyed. The main shocks and some of the most severe aftershocks triggered landslides, chiefly rock falls and minor rock slides that caused damage to towns, individual houses, and the transportation network. Beginning in the immediate aftermath of the event, and continuing during the emergency and post-emergency phases, we assisted the Italian national Department for Civil Protection in the evaluation of local landslide and hydrological risk conditions. Technical and scientific activities focused on: (i) mapping the location, type, and severity of the main ground effects produced by the earthquake shaking, (ii) evaluating and selecting sites for potential new settlements and individual buildings, including a preliminary assessment of the local geomorphological and hydrological conditions; (iii) evaluating rock fall hazard at individual sites, (iv) monitoring slope and ground deformations, and (v) designing and implementing a prototype system for the forecast of the possible occurrence of rainfall-induced landslides. To execute these activates, we exploited a wide range of methods, techniques, and technologies, and we performed repeated field surveys, the interpretation of ground and aerial photographs

  17. X-1-2 on ramp with pilots Robert Champine and Herb Hoover

    NASA Technical Reports Server (NTRS)

    1949-01-01

    The Bell Aircraft Corporation X-1-2 and two of the NACA pilots that flew the aircraft. The one on the viewer's left is Robert Champine with the other being Herbert Hoover. Champine made a total of 13 flights in the X-1, plus 9 in the D-558-1 and 12 in the D-558-2. Hoover made 14 flights in the X-1. On March 10, 1948, he reached Mach 1.065, becoming the first NACA pilot to fly faster than the speed of sound. There were five versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on Jan. 25, 1946. Powered flights began in December 1946. On Oct. 14, 1947, the X-1-1, piloted by Air Force Captain Charles 'Chuck' Yeager, became the first aircraft

  18. Evolution of Close Binary Systems

    SciTech Connect

    Yakut, K; Eggleton, P

    2005-01-24

    We collected data on the masses, radii, etc. of three classes of close binary stars: low-temperature contact binaries (LTCBs), near-contact binaries (NCBs), and detached close binaries (DCBs). They restrict themselves to systems where (1) both components are, at least arguably, near the Main Sequence, (2) the periods are less than a day, and (3) there is both spectroscopic and photometric analysis leading to reasonably reliable data. They discuss the possible evolutionary connections between these three classes, emphasizing the roles played by mass loss and angular momentum loss in rapidly-rotating cool stars.

  19. Long-Term X-Ray Variability of Circinus X-1

    NASA Technical Reports Server (NTRS)

    Saz Parkinson, P. M.; Tournear, D. M.; Bloom, E. D.; Focke, W. B.; Reilly, K. T.

    2003-01-01

    We present an analysis of long term X-ray monitoring observations of Circinus X-1 (Cir X-1) made with four different instruments: Vela 5B, Ariel V ASM, Ginga ASM, and RXTE ASM, over the course of more than 30 years. We use Lomb-Scargle periodograms to search for the approx. 16.5 day orbital period of Cir X-1 in each of these data sets and from this derive a new orbital ephemeris based solely on X-ray measurements, which we compare to the previous ephemerides obtained from radio observations. We also use the Phase Dispersion Minimization (PDM) technique, as well as FFT analysis, to verify the periods obtained from periodograms. We obtain dynamic periodograms (both Lomb-Scargle and PDM) of Cir X-1 during the RXTE era, showing the period evolution of Cir X-1, and also displaying some unexplained discrete jumps in the location of the peak power.

  20. Low autocorrelation binary sequences

    NASA Astrophysics Data System (ADS)

    Packebusch, Tom; Mertens, Stephan

    2016-04-01

    Binary sequences with minimal autocorrelations have applications in communication engineering, mathematics and computer science. In statistical physics they appear as groundstates of the Bernasconi model. Finding these sequences is a notoriously hard problem, that so far can be solved only by exhaustive search. We review recent algorithms and present a new algorithm that finds optimal sequences of length N in time O(N {1.73}N). We computed all optimal sequences for N≤slant 66 and all optimal skewsymmetric sequences for N≤slant 119.

  1. BINARY STORAGE ELEMENT

    DOEpatents

    Chu, J.C.

    1958-06-10

    A binary storage device is described comprising a toggle provided with associsted improved driver circuits adapted to produce reliable action of the toggle during clearing of the toggle to one of its two states. or transferring information into and out of the toggle. The invention resides in the development of a self-regulating driver circuit to minimize the fluctuation of the driving voltages for the toggle. The disclosed driver circuit produces two pulses in response to an input pulse: a first or ''clear'' pulse beginning nt substantially the same time but endlrg slightly sooner than the second or ''transfer'' output pulse.

  2. The ζ Aurigae Binaries

    NASA Astrophysics Data System (ADS)

    Griffin, R. Elizabeth; Ake, Thomas B.

    This opening chapter provides a brief historical overview of the ζ Aur stars, with a focus on what K.O. Wright, his predecessors and colleagues at the Dominion Astrophysical Observatory, and his contemporaries further afield, achieved during the era of pre-electronic data. It places the topic within the framework of modern observing, data management and computing, outlines the principal features of the chromospheric-eclipse phenomena which single out the ζ Aur binaries for special study, and describes the considerable potential which this remarkable yet very select group of stars offers for increasing our understanding of stellar physics.

  3. Organic functionalization of the germanium(100)- 2 x 1 semiconductor interface: Reaction chemistry, selective attachment strategies, and molecular layer deposition

    NASA Astrophysics Data System (ADS)

    Filler, Michael Aaron

    amines, nitriles, and carbonyl-containing compounds indicate that narrow product distributions can be achieved with proper control of the reaction kinetics and thermodynamics of competing pathways. Furthermore, the creation of a ultrathin polyurea film on Ge(100)-2x1 at room temperature via the binary deposition of diamines and diisocyanates is demonstrated.

  4. Effects of radiation pressure on the equipotential surfaces in X-ray binaries

    NASA Technical Reports Server (NTRS)

    Kondo, Y.; Mccluskey, G. E., Jr.; Gulden, S. L.

    1976-01-01

    Equipotential surfaces incorporating the effect of radiation pressure were computed for the X-ray binaries Cen X-3, Cyg X-1 = HDE 226868, Vela XR-1 = 3U 0900-40 = HD 77581, and 3U 1700-37 = HD 153919. The topology of the equipotential surfaces is significantly affected by radiation pressure. In particular, the so-called critical Roche (Jacobian) lobes, the traditional figure 8's, do not exist. The effects of these results on modeling X-ray binaries are discussed.

  5. Koronis binaries and the role of families in binary frequency

    NASA Astrophysics Data System (ADS)

    Merline, W. J.; Tamblyn, P. M.; Nesvorny, D.; Durda, D. D.; Chapman, C. R.; Dumas, C.; Owen, W. M.; Storrs, A. D.; Close, L. M.; Menard, F.

    2005-08-01

    Our ground-based adaptive optics observations of many larger Koronis members show no binaries, while our HST survey of smaller Koronis members (say smaller than 10 km) shows a surprising 20% binary fraction. Admittedly, this is from small-number statistics, but we nonetheless calculate a 99% confidence that the binary fraction is different from the 2% we observe among the larger (over 20km) main belt asteroids as a whole. In addition, we estimate that among the two young families (Karin and Veritas) that we surveyed for binaries in our HST Cy 13 program, the binary fraction appears to be less than 5%. These young families both have significantly smaller progenitors than the Koronis family. We have speculated that progenitor size may be a more important factor than age in determination of binary frequency. But here we suggest an alternative idea, that the binary fraction may be more related to what part of the family's size distribution is sampled. Our HST program targeted objects of the same physical sizes, but was clearly sampling further down the size distribution (to smaller sizes, relative to the largest remnant) in the Koronis sample than was the case for Karin and Veritas, which we sampled mostly at the larger sizes, relatively. Our SPH collision models are estimating the typical size-frequency distributions to be expected from catastrophic and non-catastrophic impact events. But they are also appear to be showing that the largest fragments from a collision are less likely to form binaries (as co-orbiting ejecta pairs) than are the smaller fragments. Thus, it might be expected that we would have found fewer binaries among Karin and Veritas than among the Koronis sample. In fact, models of the Karin breakup show binary formation to be unlikely in the size range measured. It some might be tempted to tie the small end of the main-belt binary population to the binaries seen among the NEAs (also small and also showing about 20% fraction), given the 20% fraction

  6. Modeling Binary Neutron Stars

    NASA Astrophysics Data System (ADS)

    Park, Conner; Read, Jocelyn; Flynn, Eric; Lockett-Ruiz, Veronica

    2016-03-01

    Gravitational waves, predicted by Einstein's Theory of Relativity, are a new frontier in astronomical observation we can use to observe phenomena in the universe. Laser Interferometer Gravitational wave Observatory (LIGO) is currently searching for gravitational wave signals, and requires accurate predictions in order to best extract astronomical signals from all other sources of fluctuations. The focus of my research is in increasing the accuracy of Post-Newtonian models of binary neutron star coalescence to match the computationally expensive Numerical models. Numerical simulations can take months to compute a couple of milliseconds of signal whereas the Post-Newtonian can generate similar signals in seconds. However the Post-Newtonian model is an approximation, e.g. the Taylor T4 Post-Newtonian model assumes that the two bodies in the binary neutron star system are point charges. To increase the effectiveness of the approximation, I added in tidal effects, resonance frequencies, and a windowing function. Using these observed effects from simulations significantly increases the Post-Newtonian model's similarity to the Numerical signal.

  7. Integrated Technologies for Surveying Artefacts Damaged by Earthquakes. Application of All-In LIDAR Techniques in the City of L'AQUILA

    NASA Astrophysics Data System (ADS)

    Clini, P.; Quattrini, R.; Fiori, F.; Nespeca, R.

    2013-07-01

    The purpose of this work is to demonstrate how, in post-earthquake intervention scenarios, the latest "all-in-one" laser technologies employed beyond their usual applications and integrated in more traditional survey methods, can define a comprehensive and original approach method in response to surveying issues, safety of the artefacts, speed and low cost of surveys, quality of data and of the models provided for damage assessments and any required action. The case study of L'Aquila is therefore significant. The red area has essentially two types of buildings: monuments and historical buildings characterised by compact urban centres. Here we document the convent of the Blessed Antonia and the Antenucci Block, as case studies and synthesis of the two types and ideal laboratories to test the chosen method. In the first case, we document the project on a building that is yet to be secured and that therefore presents delicate issues in terms of survey speed and completeness, also in relation to the precious decorations that it holds. In the other case, we document the survey of the typical block in Aquila, already secured which, given the size and complexity, requires an integrated approach, more complex and more time-consuming of methods of analysis.

  8. Modeling the Oxygen K Absorption in the Interstellar Medium: An XMM-Newton View of Sco X-1

    NASA Technical Reports Server (NTRS)

    Garcia, J.; Ramirez, J. M.; Kallman, T. R.; Witthoeft, M.; Bautista, M. A.; Mendoza, C.; Palmeri, P.; Quinet, P.

    2011-01-01

    We investigate the absorption structure of the oxygen in the interstellar medium by analyzing XMM-Newton observations of the low mass X-ray binary Sco X-1. We use simple models based on the O I atomic cross section from different sources to fit the data and evaluate the impact of the atomic data in the interpretation of astrophysical observations. We show that relatively small differences in the atomic calculations can yield spurious results. We also show that the most complete and accurate set of atomic cross sections successfully reproduce the observed data in the 21 - 24.5 Angstrom wavelength region of the spectrum. Our fits indicate that the absorption is mainly due to neutral gas with an ionization parameter of Epsilon = 10(exp -4) erg/sq cm, and an oxygen column density of N(sub O) approx. = 8-10 x 10(exp 17)/sq cm. Our models are able to reproduce both the K edge and the K(alpha) absorption line from O I, which are the two main features in this region. We find no conclusive evidence for absorption by other than atomic oxygen.

  9. Dependence of Kilohertz Quasi-periodic Oscillation Properties on the Normal-Branch Oscillation Phase in Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Yu, Wenfei; van der Klis, Michiel; Jonker, Peter G.

    2001-09-01

    We analyzed Rossi X-Ray Timing Explorer data of Scorpius X-1, which show kilohertz quasi-periodic oscillations (QPOs) and the ~6-8 Hz normal-branch oscillation (NBO) simultaneously. Using power spectra of 0.03-0.5 s data segments, we find that both the upper kilohertz QPO frequency ν2 and the ratio of lower to upper kilohertz QPO amplitude are anticorrelated to variations in the X-ray count rate taking place on the NBO timescale. The frequency dependence is similar to (but probably weaker than) that found on longer timescales, but the power ratio dependence is opposite to it. A model where radiative stresses on the disk material, modulated at the NBO frequency, lead to changes in ν2 can explain the data; this implies that some of the NBO flux changes originate from inside the inner disk radius. We discuss how these findings affect our understanding of kilohertz QPOs and of the low-frequency variability of low-mass X-ray binaries.

  10. Modeling the Oxygen K Absorption in the Interstellar Medium: An XMM-Newton View of Sco X-1

    NASA Astrophysics Data System (ADS)

    García, J.; Ramírez, J. M.; Kallman, T. R.; Witthoeft, M.; Bautista, M. A.; Mendoza, C.; Palmeri, P.; Quinet, P.

    2011-04-01

    We investigate the X-ray absorption structure of oxygen in the interstellar medium by analyzing XMM - Newton observations of the low-mass X-ray binary Sco X-1. Simple models based on the O I atomic photoabsorption cross section from different sources are used to fit the data and evaluate the impact of the atomic data on the interpretation of the observations. We show that relatively small differences in the atomic calculations can yield spurious results, and that the most complete and accurate set of atomic cross sections successfully reproduce the observed data in the 21.0-24.5 Å wavelength region of the spectrum. Our fits indicate that the absorption is mainly due to neutral gas with an ionization parameter of ξ = 10-4 erg cm s-1 and an oxygen column density of N O ≈ (8-10) × 1017 cm-2. The models are able to reproduce both the K edge and the Kα absorption line from O I which are the two main features in this region. We find no conclusive evidence for absorption by anything other than atomic oxygen.

  11. Discovery of iron line emission in the Hercules X-1 low-state spectrum with HEAO 1

    NASA Technical Reports Server (NTRS)

    Pravdo, S. H.; Boldt, E. A.; Holt, S. S.; Rothschild, R. E.; Serlemitsos, P. J.

    1978-01-01

    Results are reported for HEAO 1 observations of Her X-1 which confirm the existence of the iron line-emission feature discovered with OSO 8 in the high-state spectrum and also reveal an iron emission feature in the low-state spectrum. The iron line-emission feature in the low-state spectrum was detected at a significance level greater than 5 sigmas and is characterized by a line energy of 6.4 keV, an equivalent width larger than that of the high-state line, a binary phase dependence of the line intensity, and a line width that is intrinsically narrow in contrast to the broad high-state line. The observed line energy and narrow line width are shown to be consistent with an interpretation in terms of fluorescence emission due to X-ray heating. It is suggested that HZ Her contributes no more than about 10% of the predicted line flux, that this emission is reflected from a highly ionized plasma, and that a hot coronal gas is an important source of the low-state X-rays.

  12. MODELING THE OXYGEN K ABSORPTION IN THE INTERSTELLAR MEDIUM: AN XMM-NEWTON VIEW OF Sco X-1

    SciTech Connect

    GarcIa, J.; Bautista, M. A.; RamIrez, J. M.; Kallman, T. R.; Witthoeft, M.; Mendoza, C.; Palmeri, P.; Quinet, P. E-mail: manuel.bautista@wmich.edu E-mail: michael.c.witthoeft@nasa.gov E-mail: claudio@ivic.gob.v E-mail: quinet@umh.ac.be

    2011-04-10

    We investigate the X-ray absorption structure of oxygen in the interstellar medium by analyzing XMM - Newton observations of the low-mass X-ray binary Sco X-1. Simple models based on the O I atomic photoabsorption cross section from different sources are used to fit the data and evaluate the impact of the atomic data on the interpretation of the observations. We show that relatively small differences in the atomic calculations can yield spurious results, and that the most complete and accurate set of atomic cross sections successfully reproduce the observed data in the 21.0-24.5 A wavelength region of the spectrum. Our fits indicate that the absorption is mainly due to neutral gas with an ionization parameter of {xi} = 10{sup -4} erg cm s{sup -1} and an oxygen column density of N{sub O} {approx} (8-10) x 10{sup 17} cm{sup -2}. The models are able to reproduce both the K edge and the K{alpha} absorption line from O I which are the two main features in this region. We find no conclusive evidence for absorption by anything other than atomic oxygen.

  13. High-resolution soft X-ray spectra of Scorpius X-1 - The structure of circumsource accreting material

    NASA Technical Reports Server (NTRS)

    Kahn, S. M.; Seward, F. D.; Chlebowski, T.

    1984-01-01

    Four observations of Scorpius X-1 with the Objective Grating Spectrometer of the Einstein Observatory have provided high-resolution spectra (lambda/Delta lambda = approximately 20-50) in the wavelength range 7-46 A. The spectra reveal the presence of absorption structure due to oxygen, nitrogen, and iron, and variable emission structure associated with ionized iron and nitrogen. The strengths of these features suggest that the N/O abundance ratio in the absorbing and line emitting gas is anomalously high, which might indicate that these spectral components are associated with processed material, probably accreting matter transferred from the surface of an evolved companion. Constraints on the inclination of the system, however, imply that this cool, dense, accreting material must be well out of the plane of the binary system. Possible models for the origin and nature of this circumsource medium are discussed. An extensive discussion of the calibration of the Objective Grating Spectrometer and of the analysis of spectra acquired by that instrument is also provided.

  14. Multilevel Models for Binary Data

    ERIC Educational Resources Information Center

    Powers, Daniel A.

    2012-01-01

    The methods and models for categorical data analysis cover considerable ground, ranging from regression-type models for binary and binomial data, count data, to ordered and unordered polytomous variables, as well as regression models that mix qualitative and continuous data. This article focuses on methods for binary or binomial data, which are…

  15. Dunham coefficients for the X1Σ+ ground state of BH and BD

    NASA Astrophysics Data System (ADS)

    Shayesteh, Alireza; Ghazizadeh, Ehsan

    2015-06-01

    All available spectroscopic data for the X1Σ+, A1Π and B1Σ+ states of BH and BD have been combined in a multi-isotopologue fit to obtain Dunham coefficients for the X1Σ+ ground state. With no vibration-rotation data available for BD, the only way to determine the v = 1 ← 0 interval in the X1Σ+ ground state of BD was to use the 1-1 and 1-0 bands of the B1Σ+ - X1Σ+ system. An incorrect J assignment was found in the published data of the 1-0 band of the B1Σ+ - X1Σ+ system of BD, making them inconsistent with the more accurate data from the A1Π - X1Σ+ system. With the correct J assignment, the v = 1 ← 0 interval in the X1Σ+, A1Π and B1Σ+ states of 11BD were determined to be 1690.773, 1581.095 and 1687.90 cm-1, respectively. The values listed in Huber and Herzberg's book differ from the above values by ∼2B, because they are based on an incorrect J assignment.

  16. Signature Visualization of Software Binaries

    SciTech Connect

    Panas, T

    2008-07-01

    In this paper we present work on the visualization of software binaries. In particular, we utilize ROSE, an open source compiler infrastructure, to pre-process software binaries, and we apply a landscape metaphor to visualize the signature of each binary (malware). We define the signature of a binary as a metric-based layout of the functions contained in the binary. In our initial experiment, we visualize the signatures of a series of computer worms that all originate from the same line. These visualizations are useful for a number of reasons. First, the images reveal how the archetype has evolved over a series of versions of one worm. Second, one can see the distinct changes between version. This allows the viewer to form conclusions about the development cycle of a particular worm.

  17. Evidence for an approx. 300 day period in Cygnus X-1

    SciTech Connect

    Priedhorsky, W.C.; Terrell, J.; Holt, S.S.

    1983-07-01

    We present the time history of X-ray emission from Cyg X-1 over an 11 year period, with 10 day resolution. The data were obtained by experiments on the Vela 5B (1969--1979) and Ariel 5 (1974--1980) satellites. Cyg X-1 varies by approx.25% with a 294 +- 4 day period. This modulation is apparently unrelated to the known transitions between the source high and low states. Flux minima occur at 1974.05+nP. The observed period is within the possible range for the precession period of an accretion disk, or of the companion star HDE 226868, in the Cyg X-1 system.

  18. Contact Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Rieger, Samantha

    2015-05-01

    Recent observations have found that some contact binaries are oriented such that the secondary impacts with the primary at a high inclination. This research investigates the evolution of how such contact binaries came to exist. This process begins with an asteroid pair, where the secondary lies on the Laplace plane. The Laplace plane is a plane normal to the axis about which the pole of a satellites orbit precesses, causing a near constant inclination for such an orbit. For the study of the classical Laplace plane, the secondary asteroid is in circular orbit around an oblate primary with axial tilt. This system is also orbiting the Sun. Thus, there are two perturbations on the secondarys orbit: J2 and third body Sun perturbations. The Laplace surface is defined as the group of orbits that lie on the Laplace plane at varying distances from the primary. If the secondary is very close to the primary, the inclination of the Laplace plane will be near the equator of the asteroid, while further from the primary the inclination will be similar to the asteroid-Sun plane. The secondary will lie on the Laplace plane because near the asteroid the Laplace plane is stable to large deviations in motion, causing the asteroid to come to rest in this orbit. Assuming the secondary is asymmetrical in shape and the bodys rotation is synchronous with its orbit, the secondary will experience the BYORP effect. BYORP can cause secular motion such as the semi-major axis of the secondary expanding or contracting. Assuming the secondary expands due to BYORP, the secondary will eventually reach the unstable region of the Laplace plane. The unstable region exists if the primary has an obliquity of 68.875 degrees or greater. The unstable region exists at 0.9 Laplace radius to 1.25 Laplace radius, where the Laplace radius is defined as the distance from the central body where the inclination of the Laplace plane orbit is half the obliquity. In the unstable region, the eccentricity of the orbit

  19. Binaries and distances

    NASA Astrophysics Data System (ADS)

    Pourbaix, D.; Arenou, F.; Halbwachs, J.-L.; Siopis, C.

    2013-02-01

    Gaia's five-year observation baseline might naively lead to the expectation that it will be possible to fit the parallax of any sufficiently nearby object with the default five-parameter model (position at a reference epoch, parallax and proper motion). However, simulated Gaia observations of a `model Universe' composed of nearly 107 objects, 50% of which turn out to be multiple stars, show that the single-star hypothesis can severely affect parallax estimation and that more sophisticated models must be adopted. In principle, screening these spurious single-star solutions is rather straightforward, for example by evaluating the quality of the fits. However, the simulated Gaia observations also reveal that some seemingly acceptable single-star solutions can nonetheless lead to erroneous distances. These solutions turn out to be binaries with an orbital period close to one year. Without auxiliary (e.g., spectroscopic) data, they will remain unnoticed.

  20. VLSI binary updown counter

    NASA Technical Reports Server (NTRS)

    Truong, Trieu-Kie (Inventor); Hsu, In-Shek (Inventor); Reed, Irving S. (Inventor)

    1989-01-01

    A pipeline binary updown counter is comprised of simple stages that may be readily replicated. Each stage is defined by the Boolean logic equation: A(sub n)(t) = A(sub n)(t - 1) exclusive OR (U AND P(sub n)) inclusive OR (D AND Q(sub n)), where A(sub n)(t) denotes the value of the nth bit at time t. The input to the counter has three values represented by two binary signals U and D such that if both are zero, the input is zero, if U = 0 and D = 1, the input is -1 and if U = 1 and D = 0, the input is +1. P(sub n) represents a product of A(sub k)'s for 1 is less than or equal to k is less than or equal to -1, while Q(sub n) represents the product of bar A's for 1 is less than or equal to K is less than or equal to n - 1, where bar A(sub k) is the complement of A(sub k) and P(sub n) and Q(sub n) are expressed as the following two equations: P(sub n) = A(sub n - 1) A(sub n - 2)...A(sub 1) and Q(sub n) = bar A(sub n - 1) bar A(sub n - 2)...bar A(sub 1), which can be written in recursive form as P(sub n) = P(sub n - 1) AND bar A(sub n - 1) and Q(sub n) = Q(sub n - 1) AND bar A(sub n - 1) with the initial values P(sub 1) = 1 and Q(sub 1) = 1.

  1. A collision risk model to predict avian fatalities at wind facilities: an example using golden eagles, Aquila chrysaetos

    USGS Publications Warehouse

    New, Leslie; Bjerre, Emily; Millsap, Brian A.; Otto, Mark C.; Runge, Michael C.

    2015-01-01

    Wind power is a major candidate in the search for clean, renewable energy. Beyond the technical and economic challenges of wind energy development are environmental issues that may restrict its growth. Avian fatalities due to collisions with rotating turbine blades are a leading concern and there is considerable uncertainty surrounding avian collision risk at wind facilities. This uncertainty is not reflected in many models currently used to predict the avian fatalities that would result from proposed wind developments. We introduce a method to predict fatalities at wind facilities, based on pre-construction monitoring. Our method can directly incorporate uncertainty into the estimates of avian fatalities and can be updated if information on the true number of fatalities becomes available from post-construction carcass monitoring. Our model considers only three parameters: hazardous footprint, bird exposure to turbines and collision probability. By using a Bayesian analytical framework we account for uncertainties in these values, which are then reflected in our predictions and can be reduced through subsequent data collection. The simplicity of our approach makes it accessible to ecologists concerned with the impact of wind development, as well as to managers, policy makers and industry interested in its implementation in real-world decision contexts. We demonstrate the utility of our method by predicting golden eagle (Aquila chrysaetos) fatalities at a wind installation in the United States. Using pre-construction data, we predicted 7.48 eagle fatalities year-1 (95% CI: (1.1, 19.81)). The U.S. Fish and Wildlife Service uses the 80th quantile (11.0 eagle fatalities year-1) in their permitting process to ensure there is only a 20% chance a wind facility exceeds the authorized fatalities. Once data were available from two-years of post-construction monitoring, we updated the fatality estimate to 4.8 eagle fatalities year-1 (95% CI: (1.76, 9.4); 80th quantile, 6

  2. Influence of contamination by organochlorine pesticides and polychlorinated biphenyls on the breeding of the spanish imperial eagle (Aquila adalberti).

    PubMed

    Hernández, Mauro; González, Luis M; Oria, Javier; Sánchez, Roberto; Arroyo, Beatriz

    2008-02-01

    We evaluated temporal and regional trends of organochlorine (OC) pesticide (including polychlorinated biphenyl [PCB]) levels in eggs of the Spanish Imperial Eagle (Aquila adalberti) collected in Spain between 1972 and 2003. Levels of p,p'-dichlorodiphenyldichloroethylene (DDE) and PCBs varied significantly (p = 0.022) among regions (central, western, and Doñana), being higher in Doñana than in the central and western populations (DDE: 1.64 +/- 5.56, 0.816 +/- 1.70, and 1.1 +/- 2.66 microg/g, respectively; PCBs: 1.189 +/- 5.0, 0.517 +/- 1.55, and 0.578 +/- 1.75 microg/g, respectively). Levels of DDE decreased with time, but a significant interaction was observed between region and time. In Doñana, egg volume and breadth as well as Ratcliffe Index were significantly lower after DDT use (p = 0.0018) than during the pre-DDT period (p = 0.0018); eggs were significantly smaller overall than in the other two regions (p = 0.04) and were smaller when DDE levels increased, even when controlling for regional differences (p = 0.04). Productivity in Doñana was significantly lower than in the other regions (p < 0.001). Clutch size in Doñana varied according to DDE concentrations (p = 0.01), with the highest DDE concentrations found in clutches consisting of one egg. When considering eggs with DDE levels greater than 3.5 microg/g, a significant effect of DDE on fertility was found (p = 0.03). Clutches with DDE levels greater than 4.0 microg/g had a higher probability of hatching failure (p = 0.07) and produced fewer fledglings (p = 0.03). If we consider 3.5 microg/g as the lowest-observable-adverse-effect level, the proportion of sampled clutches that exceeded that level in Doñana (29%) was significantly higher than in other regions (p < 0.001). These eggs showed a mean percentage of thinning of 16.72%. Contamination by OCs, mainly DDE, could explain, at least in part, the low productivity of the Spanish Imperial Eagles in Doñana. PMID:18348639

  3. A Collision Risk Model to Predict Avian Fatalities at Wind Facilities: An Example Using Golden Eagles, Aquila chrysaetos.

    PubMed

    New, Leslie; Bjerre, Emily; Millsap, Brian; Otto, Mark C; Runge, Michael C

    2015-01-01

    Wind power is a major candidate in the search for clean, renewable energy. Beyond the technical and economic challenges of wind energy development are environmental issues that may restrict its growth. Avian fatalities due to collisions with rotating turbine blades are a leading concern and there is considerable uncertainty surrounding avian collision risk at wind facilities. This uncertainty is not reflected in many models currently used to predict the avian fatalities that would result from proposed wind developments. We introduce a method to predict fatalities at wind facilities, based on pre-construction monitoring. Our method can directly incorporate uncertainty into the estimates of avian fatalities and can be updated if information on the true number of fatalities becomes available from post-construction carcass monitoring. Our model considers only three parameters: hazardous footprint, bird exposure to turbines and collision probability. By using a Bayesian analytical framework we account for uncertainties in these values, which are then reflected in our predictions and can be reduced through subsequent data collection. The simplicity of our approach makes it accessible to ecologists concerned with the impact of wind development, as well as to managers, policy makers and industry interested in its implementation in real-world decision contexts. We demonstrate the utility of our method by predicting golden eagle (Aquila chrysaetos) fatalities at a wind installation in the United States. Using pre-construction data, we predicted 7.48 eagle fatalities year-1 (95% CI: (1.1, 19.81)). The U.S. Fish and Wildlife Service uses the 80th quantile (11.0 eagle fatalities year-1) in their permitting process to ensure there is only a 20% chance a wind facility exceeds the authorized fatalities. Once data were available from two-years of post-construction monitoring, we updated the fatality estimate to 4.8 eagle fatalities year-1 (95% CI: (1.76, 9.4); 80th quantile, 6

  4. Facebook, Quality of Life, and Mental Health Outcomes in Post-Disaster Urban Environments: The L’Aquila Earthquake Experience

    PubMed Central

    Masedu, Francesco; Mazza, Monica; Di Giovanni, Chiara; Calvarese, Anna; Tiberti, Sergio; Sconci, Vittorio; Valenti, Marco

    2014-01-01

    Background: An understudied area of interest in post-disaster public health is individuals’ use of social networks as a potential determinant of quality of life (QOL) and mental health outcomes. A population-based cross-sectional study was carried out to examine whether continual use of online social networking (Facebook) in an adult population following a massive earthquake was correlated with prevalence of depression and post-traumatic stress disorders (PTSD) and QOL outcomes. Methods: Participants were a sample of 890 adults aged 25–54 who had been exposed to the L’Aquila earthquake of 2009. Definition of “user” required a daily connection to the Facebook online social network for more than 1 h per day from at least 2 years. Depression and PTSD were assessed using the Screening Questionnaire for Disaster Mental Health. QOL outcomes were measured using the World Health Organisation Quality of Life BREF (WHOQOL-BREF) instrument. Logistic regression was carried out to calculate the prevalence odds ratios (POR) for social network use and other covariates. Results: Two hundred and twenty one of 423 (52.2%) men, and 195 of 383 (50.9%) women, had been using Facebook as social network for at least 2 years prior to our assessment. Social network use correlated with both depression and PTSD, after adjusting for gender. A halved risk of depression was found in users vs. non-users (POR 0.50 ± 0.16). Similarly, a halved risk of PTSD in users vs. non-users (POR 0.47 ± 0.14) was found. Both men and women using online social networks had significantly higher QOL scores in the psychological and social domains of the WHOQOL-BREF. Conclusion: Social network use among adults 25–54 years old has a positive impact on mental health and QOL outcomes in the years following a disaster. The use of social networks may be an important tool for coping with the mental health outcomes of disruptive natural disasters, helping to maintain, if not improve, QOL in

  5. 3D Faulting Numerical Model Related To 2009 L'Aquila Earthquake Based On DInSAR Observations

    NASA Astrophysics Data System (ADS)

    Castaldo, Raffaele; Tizzani, Pietro; Solaro, Giuseppe; Pepe, Susi; Lanari, Riccardo

    2014-05-01

    We investigate the surface displacements in the area affected by the April 6, 2009 L'Aquila earthquake (Central Italy) through an advanced 3D numerical modeling approach, by exploiting DInSAR deformation velocity maps based on ENVISAT (Ascending and Descending orbits) and COSMO-SkyMed data (Ascending orbit). We benefited from the available geological and geophysical information to investigate the impact of known buried structures on the modulation of the observed ground deformation field; in this context we implemented the a priori information in a Finite Element (FE) Environment considering a structural mechanical physical approach. The performed analysis demonstrate that the displacement pattern associated with the Mw 6.3 main-shock event is consistent with the activation of several fault segments of the Paganica fault. In particular, we analyzed the seismic events in a structural mechanical context under the plane stress mode approximation to solve for the retrieved displacements. We defined the sub-domain setting of the 3D FEM model using the information derived from the CROOP M-15 seismic line. We assumed stationarity and linear elasticity of the involved materials by considering a solution of classical equilibrium mechanical equations. We evolved our model through two stages: the model compacted under the weight of the rock successions (gravity loading) until it reached a stable equilibrium. At the second stage (co-seismic), where the stresses were released through a slip along the faults, by using an optimization procedure we retrieved: (i) the active seismogenic structures responsible for the observed ground deformation, (ii) the effects of the different mechanical constraints on the ground deformation pattern and (iii) the spatial distribution of the retrieved stress field. We evaluated the boundary setting best fit configuration responsible for the observed ground deformation. To this aim, we first generated several forward structural mechanical models

  6. A Collision Risk Model to Predict Avian Fatalities at Wind Facilities: An Example Using Golden Eagles, Aquila chrysaetos

    PubMed Central

    New, Leslie; Bjerre, Emily; Millsap, Brian; Otto, Mark C.; Runge, Michael C.

    2015-01-01

    Wind power is a major candidate in the search for clean, renewable energy. Beyond the technical and economic challenges of wind energy development are environmental issues that may restrict its growth. Avian fatalities due to collisions with rotating turbine blades are a leading concern and there is considerable uncertainty surrounding avian collision risk at wind facilities. This uncertainty is not reflected in many models currently used to predict the avian fatalities that would result from proposed wind developments. We introduce a method to predict fatalities at wind facilities, based on pre-construction monitoring. Our method can directly incorporate uncertainty into the estimates of avian fatalities and can be updated if information on the true number of fatalities becomes available from post-construction carcass monitoring. Our model considers only three parameters: hazardous footprint, bird exposure to turbines and collision probability. By using a Bayesian analytical framework we account for uncertainties in these values, which are then reflected in our predictions and can be reduced through subsequent data collection. The simplicity of our approach makes it accessible to ecologists concerned with the impact of wind development, as well as to managers, policy makers and industry interested in its implementation in real-world decision contexts. We demonstrate the utility of our method by predicting golden eagle (Aquila chrysaetos) fatalities at a wind installation in the United States. Using pre-construction data, we predicted 7.48 eagle fatalities year-1 (95% CI: (1.1, 19.81)). The U.S. Fish and Wildlife Service uses the 80th quantile (11.0 eagle fatalities year-1) in their permitting process to ensure there is only a 20% chance a wind facility exceeds the authorized fatalities. Once data were available from two-years of post-construction monitoring, we updated the fatality estimate to 4.8 eagle fatalities year-1 (95% CI: (1.76, 9.4); 80th quantile, 6

  7. THE CHANGE OF THE ORBITAL PERIODS ACROSS ERUPTIONS AND THE EJECTED MASS FOR RECURRENT NOVAE CI AQUILAE AND U SCORPII

    SciTech Connect

    Schaefer, Bradley E.

    2011-12-01

    I report on the cumulative results from a program started 24 years ago designed to measure the orbital period change of recurrent novae (RNe) across an eruption. The goal is to use the orbital period change to measure the mass ejected during each eruption as the key part of trying to measure whether the RNe white dwarfs are gaining or losing mass over an entire eruption cycle, and hence whether they can be progenitors for Type Ia supernovae. This program has now been completed for two eclipsing RNe: CI Aquilae (CI Aql) across its eruption in 2000 and U Scorpii (U Sco) across its eruption in 1999. For CI Aql, I present 78 eclipse times from 1991 to 2009 (including four during the tail of the 2000 eruption) plus two eclipses from 1926 and 1935. For U Sco, I present 67 eclipse times, including 46 times during quiescence from 1989 to 2009, plus 21 eclipse times in the tails of the 1945, 1999, and 2010 eruptions. The eclipse times during the tails of eruptions are systematically and substantially shifted with respect to the ephemerides from the eclipses in quiescence, with this being caused by shifts of the center of light during the eruption. These eclipse times are plotted on an O - C diagram and fitted to models with a steady period change ( P-dot ) between eruptions (caused by, for example, conservative mass transfer) plus an abrupt period change ({Delta}P) at the time of eruption. The primary uncertainty arises from the correlation between {Delta}P with P-dot , such that a more negative P-dot makes for a more positive {Delta}P. For CI Aql, the best fit is {Delta}P = -3.7{sup +9.2}{sub -7.3} Multiplication-Sign 10{sup -7}. For U Sco, the best fit is {Delta}P = (+ 43 {+-} 69) Multiplication-Sign 10{sup -7} days. These period changes can directly give a dynamical measure of the mass ejected (M{sub ejecta}) during each eruption with negligible sensitivity to the stellar masses and no uncertainty from distances. For CI Aql, the 1{sigma} upper limit is M{sub ejecta} < 10

  8. Multiple Views of X1.4 Solar Flare on July 12, 2012

    NASA Video Gallery

    This video shows the July 12, 2012 X1.4 class solar flare in a variety of wavelength; 131- Teal colored, 335 - blue colored, 171 - yellow colored and finally a combined wavelength view. All video w...

  9. X1.6 Class Solar Flare on Sept. 10, 2014

    NASA Video Gallery

    An X1.6 class solar flare flashes in the middle of the sun on Sept. 10, 2014. These images were captured by NASA's Solar Dynamics Observatory. It first shows the flare in the 171 Angstrom wavelengt...

  10. Observation of the X-ray source Sco X-1 from Skylab. [radiant flux density

    NASA Technical Reports Server (NTRS)

    Wilson, R. M.

    1977-01-01

    An attempt to observe the discrete X-ray source Sco X-1 on 20 September 1973 between 0856 and 0920 UT is reported. Data obtained with the ATM/S-056 X-ray event analyzer, in particular the flux observed with the 1.71 to 4.96 KeV counter, is analyzed. No photographic image of the source was obtained because Sco X-1 was outside the field of view of the X-ray telescope.

  11. What is special about Cygnus X-1?. [evidence for a black hole

    NASA Technical Reports Server (NTRS)

    Boldt, E. A.; Holt, S. S.; Rothschild, R. E.; Serlemitsos, P. J.

    1974-01-01

    The X-ray evidence from several experiments is reviewed, with special emphasis on those characteristics which appear to distinguish Cygnus X-1 from other compact X-ray emitting objects. Data are examined within the context of a model in which millisecond bursts are superposed upon shot-noise fluctuations arising from events of durations on the order of a second. Possible spectral-temporal correlations are investigated which provide additional evidence that Cygnus X-1 is very likely a black hole.

  12. BINARIES AMONG DEBRIS DISK STARS

    SciTech Connect

    Rodriguez, David R.; Zuckerman, B.

    2012-02-01

    We have gathered a sample of 112 main-sequence stars with known debris disks. We collected published information and performed adaptive optics observations at Lick Observatory to determine if these debris disks are associated with binary or multiple stars. We discovered a previously unknown M-star companion to HD 1051 at a projected separation of 628 AU. We found that 25% {+-} 4% of our debris disk systems are binary or triple star systems, substantially less than the expected {approx}50%. The period distribution for these suggests a relative lack of systems with 1-100 AU separations. Only a few systems have blackbody disk radii comparable to the binary/triple separation. Together, these two characteristics suggest that binaries with intermediate separations of 1-100 AU readily clear out their disks. We find that the fractional disk luminosity, as a proxy for disk mass, is generally lower for multiple systems than for single stars at any given age. Hence, for a binary to possess a disk (or form planets) it must either be a very widely separated binary with disk particles orbiting a single star or it must be a small separation binary with a circumbinary disk.

  13. Reduced vas deferens contraction and male infertility in mice lacking P2X1 receptors.

    PubMed

    Mulryan, K; Gitterman, D P; Lewis, C J; Vial, C; Leckie, B J; Cobb, A L; Brown, J E; Conley, E C; Buell, G; Pritchard, C A; Evans, R J

    2000-01-01

    P2X1 receptors for ATP are ligand-gated cation channels, present on many excitable cells including vas deferens smooth muscle cells. A substantial component of the contractile response of the vas deferens to sympathetic nerve stimulation, which propels sperm into the ejaculate, is mediated through P2X receptors. Here we show that male fertility is reduced by approximately 90% in mice with a targeted deletion of the P2X1 receptor gene. Male mice copulate normally--reduced fertility results from a reduction of sperm in the ejaculate and not from sperm dysfunction. Female mice and heterozygote mice are unaffected. In P2X1-receptor-deficient mice, contraction of the vas deferens to sympathetic nerve stimulation is reduced by up to 60% and responses to P2X receptor agonists are abolished. These results show that P2X1 receptors are essential for normal male reproductive function and suggest that the development of selective P2X1 receptor antagonists may provide an effective non-hormonal male contraceptive pill. Also, agents that potentiate the actions of ATP at P2X1 receptors may be useful in the treatment of male infertility. PMID:10638758

  14. BDB: The Binary Star Database

    NASA Astrophysics Data System (ADS)

    Dluzhnevskaya, O.; Kaygorodov, P.; Kovaleva, D.; Malkov, O.

    2014-05-01

    Description of the Binary star DataBase (BDB, http://bdb.inasan.ru), the world's principal database of binary and multiple systems of all observational types, is presented in the paper. BDB contains data on physical and positional parameters of 100,000 components of 40,000 systems of multiplicity 2 to 20, belonging to various observational types: visual, spectroscopic, eclipsing, etc. Information on these types of binaries is obtained from heterogeneous sources of data - astronomical and. Organization of the information is based on the careful cross-identification of the objects. BDB can be queried by star identifier, coordinates, and other parameters.

  15. New Interacting Binaries Identified by the Chandra Galactic Bulge Survey

    NASA Astrophysics Data System (ADS)

    Britt, Christopher; Hynes, R. I.; Jonker, P. G.; Bassa, C. G.; Nelemans, G.; Steeghs, D.; Torres, M. A. P.; Maccarone, T. J.; Greiss, S.; Mikles, V. J.; Gossen, L.; Collazzi, A. C.; Galactic Bulge Survey Collaboration

    2012-01-01

    The Chandra Galactic Bulge Survey (CGBS) is a shallow X-ray survey of 2 6x1 degree strips above and below the Galactic Plane, where extinction and crowding are substantially lower than in the plane itself. The strategy for the CGBS is to go deep enough in the X-ray to see quiescent Low Mass X-ray Binaries (qLMXB), but to remain shallow enough to avoid an overabundance of Cataclysmic Variables (CVs), with the goal of testing binary evolution models and greatly expanding the sample of LMXBs for optical follow up including mass determination. We present classification of selected X-ray emitting interacting binaries out of 1234 X-ray sources identified in the CGBS. Each source exhibits emission lines in its optical/IR spectrum. The optical variability of each source was also examined to determine lightcurve morphology and periodicity. Combining spectral information, lightcurve morphology, and X-ray to optical flux ratios enables classification of each of these sources. This work is supported by the National Science Foundation under Grant No.AST-0908789.

  16. Evidence of Quaternary rock avalanches in the central Apennines: new data and interpretation of the huge clastic deposit of the L'Aquila basin (central Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Esposito, Carlo; Scarascia Mugnozza, Gabriele; Tallini, Marco; Della Seta, Marta

    2014-05-01

    Active extensional tectonics and widespread seismicity affect the axial zone of the central Apennines (Italy) and led to the formation of several plio-quaternary intermontane basins, whose morpho-evolution was controlled by the coupling of tectonic and climatic inputs. Common features of the Apennines intermontane basins as well as their general morpho-evolution are known. Nonetheless, the complex interaction among regional uplift, local fault displacements and morpho-climatic factors caused differences in the denudational processes of the single intermontane basins. Such a dynamic response left precious records in the landscape, which in some cases testify for the occurrence of huge, catastrophic rock slope failures. Several Quaternary rock avalanches have been identified in central Apennines, which are often associated with Deep Seated Gravitational Slope Deformation (DSGSD) and thus strictly related to the geological-structural setting as well as to the Quaternary morpho-structural evolution of the mountain chain. The L'Aquila basin is one of the intermontane tectonic depression aligned along the Middle Aterno River Valley and was the scene of strong historical earthquakes, among which the last destructive event occurred on April 6, 2009 (Mw 6.3). We present here the evidence that the huge clastic deposit on which the city of L'Aquila was built up is the body of a rock avalanche detached from the southern slope of the Gran Sasso Range. The clastic deposit elongates for 13 km to the SW, from the Assergi Plain to L'Aquila and is characterized by typical morphological features such as hummocky topography, compressional ridges and run-up on the opposite slope. Sedimentological characters of the deposit and grain size analyses on the matrix let us confirm the genetic interpretation, while borehole data and significant cross sections allowed us reconstructing the 3D shape and volume of the clastic body. Finally, morphometric analyses of the Gran Sasso Range southern

  17. A methodological non destructive approach for the conservation or structural repair of the Medioeval stone pillars of the Basilica of Santa Maria di Collemaggio in L'Aquila.

    NASA Astrophysics Data System (ADS)

    Raimondo, Quaresima; Elena, Antonacci; Felice, Fusco; Antonio, Filippone; Lorenzo, Fanale; Galeota, Dante

    2015-04-01

    The Medioeval Basilica of Santa Maria of Collemaggio in L'Aquila (XII century) due to the history and the election of Pope Celestino V, the Celestine Pardon, as well as to the artistic features, has a great religious and historic relevance. The whole Basilica was severely damaged during the earthquake of April 2009 and in particular the transetto zone with the cupola collapsed and ruined completely. By means of the project "Starting Afresh with Collemaggio" the Italian company Eni signs a memorandum of understanding with the city of L'Aquila for the restoration of the monument and of Collemaggio site. For this reason a wide and complex multidisciplinary diagnostic campaign was carried out in order to prepare the final design. A specific aspect concerned the diagnosis of the fourteen octagonal pillars of the central nave in terms of state of conservation and structural behavior. Each pillar consists, more or less, in forty big squared blocks of different local carbonatic stones. The diagnosis was preliminary executed by means of visual checks and mapping of the materials and of the structural damages. Subsequently non destructrutive ultrasonic and endoscopic techniques was carried out. The ultrasonic data were elaborated in order to obtain distribution maps of the velocity in the plane sections. To understanding the compressive strength of the stones and the resistance of the pillars, according to structural instances, destructive, compressive tests, and non destructive, ultrasonic and sclerometric measures, were performed of carbonatic blocks quarried in the sourroundings of L'Aquila. The compressive destructive results, inclusive of ultrasonic and sclerometric results, were compared with those non destructive obtained on the stone blocks of the pillars. The results allow to establish that three typologies of carbonatic stone were used. In many cases the surface of the stone, due to previously heartquake, was replaced with thick pieces of different stones

  18. Slope instability mapping around L'Aquila (Abruzzo, Italy) with Persistent Scatterers Interferometry from ERS, ENVISAT and RADARSAT datasets

    NASA Astrophysics Data System (ADS)

    Righini, Gaia; Del Conte, Sara; Cigna, Francesca; Casagli, Nicola

    2010-05-01

    In the last decade Persistent Scatterers Interferometry (PSI) was used in natural hazards investigations with significant results and it is considered a helpful tool in ground deformations detection and mapping (Berardino et. al., 2003; Colesanti et al., 2003; Colesanti & Wasowski, 2006; Hilley et al., 2004). In this work results of PSI processing were interpreted after the main seismic shock that affected the Abruzzo region (Central Italy) on 6th of April 2009, in order to carry out a slope instability mapping according to the requirement of National Department of Civil Protection and in the framework of the Landslides thematic services of the EU FP7 project ‘SAFER' (Services and Applications For Emergency Response - Grant Agreement n° 218802). The area of interest was chosen in almost 460 km2 around L'Aquila according the highest probability of reactivations of landslides which depends on the local geological conditions, on the epicenter location and on other seismic parameters (Keefer, 1984). The radar images datasets were collected in order to provide estimates of the mean yearly velocity referred to two distinct time intervals: historic ERS (1992-2000) and recent ENVISAT (2002-2009), RADARSAT (2003-2009); the ERS and RADARSAT images were processed by Tele-Rilevamento Europa (TRE) using PS-InSAR(TM) technique, while the ENVISAT images were processed by e-GEOS using PSP-DIFSAR technique. A pre-existing landslide inventory map was updated through the integration of conventional photo interpretation and the radar-interpretation chain, as defined by Farina et al. (2008) and reported in literature (Farina et al. 2006, Meisina et al. 2007, Pancioli et al., 2008; Righini et al., 2008, Casagli et al., 2008, Herrera et al., 2009). The data were analyzed and interpreted in Geographic Information System (GIS) environment. Main updates of the pre-existing landslides are focusing on the identification of new landslides, modification of boundaries through the spatial

  19. Binary Oscillatory Crossflow Electrophoresis

    NASA Technical Reports Server (NTRS)

    Molloy, Richard F.; Gallagher, Christopher T.; Leighton, David T., Jr.

    1997-01-01

    Electrophoresis has long been recognized as an effective analytic technique for the separation of proteins and other charged species, however attempts at scaling up to accommodate commercial volumes have met with limited success. In this report we describe a novel electrophoretic separation technique - Binary Oscillatory Crossflow Electrophoresis (BOCE). Numerical simulations indicate that the technique has the potential for preparative scale throughputs with high resolution, while simultaneously avoiding many problems common to conventional electrophoresis. The technique utilizes the interaction of an oscillatory electric field and a transverse oscillatory shear flow to create an active binary filter for the separation of charged protein species. An oscillatory electric field is applied across the narrow gap of a rectangular channel inducing a periodic motion of charged protein species. The amplitude of this motion depends on the dimensionless electrophoretic mobility, alpha = E(sub o)mu/(omega)d, where E(sub o) is the amplitude of the electric field oscillations, mu is the dimensional mobility, omega is the angular frequency of oscillation and d is the channel gap width. An oscillatory shear flow is induced along the length of the channel resulting in the separation of species with different mobilities. We present a model that predicts the oscillatory behavior of charged species and allows estimation of both the magnitude of the induced convective velocity and the effective diffusivity as a function of a in infinitely long channels. Numerical results indicate that in addition to the mobility dependence, the steady state behavior of solute species may be strongly affected by oscillating fluid into and out of the active electric field region at the ends of the cell. The effect is most pronounced using time dependent shear flows of the same frequency (cos((omega)t)) flow mode) as the electric field oscillations. Under such conditions, experiments indicate that

  20. Stability of binaries. Part II: Rubble-pile binaries

    NASA Astrophysics Data System (ADS)

    Sharma, Ishan

    2016-10-01

    We consider the stability of the binary asteroids whose members are granular aggregates held together by self-gravity alone. A binary is said to be stable whenever both its members are orbitally and structurally stable to both orbital and structural perturbations. To this end, we extend the stability analysis of Sharma (Sharma [2015] Icarus, 258, 438-453), that is applicable to binaries with rigid members, to the case of binary systems with rubble members. We employ volume averaging (Sharma et al. [2009] Icarus, 200, 304-322), which was inspired by past work on elastic/fluid, rotating and gravitating ellipsoids. This technique has shown promise when applied to rubble-pile ellipsoids, but requires further work to settle some of its underlying assumptions. The stability test is finally applied to some suspected binary systems, viz., 216 Kleopatra, 624 Hektor and 90 Antiope. We also see that equilibrated binaries that are close to mobilizing their maximum friction can sustain only a narrow range of shapes and, generally, congruent shapes are preferred.

  1. Cryptography with DNA binary strands.

    PubMed

    Leier, A; Richter, C; Banzhaf, W; Rauhe, H

    2000-06-01

    Biotechnological methods can be used for cryptography. Here two different cryptographic approaches based on DNA binary strands are shown. The first approach shows how DNA binary strands can be used for steganography, a technique of encryption by information hiding, to provide rapid encryption and decryption. It is shown that DNA steganography based on DNA binary strands is secure under the assumption that an interceptor has the same technological capabilities as sender and receiver of encrypted messages. The second approach shown here is based on steganography and a method of graphical subtraction of binary gel-images. It can be used to constitute a molecular checksum and can be combined with the first approach to support encryption. DNA cryptography might become of practical relevance in the context of labelling organic and inorganic materials with DNA 'barcodes'. PMID:10963862

  2. Separation in 5 Msun Binaries

    NASA Astrophysics Data System (ADS)

    Evans, Nancy R.; Bond, H. E.; Schaefer, G.; Mason, B. D.; Karovska, M.; Tingle, E.

    2013-01-01

    Cepheids (5 Msun stars) provide an excellent sample for determining the binary properties of fairly massive stars. International Ultraviolet Explorer (IUE) observations of Cepheids brighter than 8th magnitude resulted in a list of ALL companions more massive than 2.0 Msun uniformly sensitive to all separations. Hubble Space Telescope Wide Field Camera 3 (WFC3) has resolved three of these binaries (Eta Aql, S Nor, and V659 Cen). Combining these separations with orbital data in the literature, we derive an unbiased distribution of binary separations for a sample of 18 Cepheids, and also a distribution of mass ratios. The distribution of orbital periods shows that the 5 Msun binaries prefer shorter periods than 1 Msun stars, reflecting differences in star formation processes.

  3. CHAOTIC ZONES AROUND GRAVITATING BINARIES

    SciTech Connect

    Shevchenko, Ivan I.

    2015-01-20

    The extent of the continuous zone of chaotic orbits of a small-mass tertiary around a system of two gravitationally bound primaries of comparable masses (a binary star, a binary black hole, a binary asteroid, etc.) is estimated analytically, as a function of the tertiary's orbital eccentricity. The separatrix map theory is used to demonstrate that the central continuous chaos zone emerges (above a threshold in the primaries' mass ratio) due to overlapping of the orbital resonances corresponding to the integer ratios p:1 between the tertiary and the central binary periods. In this zone, the unlimited chaotic orbital diffusion of the tertiary takes place, up to its ejection from the system. The primaries' mass ratio, above which such a chaotic zone is universally present at all initial eccentricities of the tertiary, is estimated. The diversity of the observed orbital configurations of biplanetary and circumbinary exosystems is shown to be in accord with the existence of the primaries' mass parameter threshold.

  4. An adaptable binary entropy coder

    NASA Technical Reports Server (NTRS)

    Kiely, A.; Klimesh, M.

    2001-01-01

    We present a novel entropy coding technique which is based on recursive interleaving of variable-to-variable length binary source codes. We discuss code design and performance estimation methods, as well as practical encoding and decoding algorithms.

  5. Simulating relativistic binaries with Whisky

    NASA Astrophysics Data System (ADS)

    Baiotti, L.

    We report about our first tests and results in simulating the last phase of the coalescence and the merger of binary relativistic stars. The simulations were performed using our code Whisky and mesh refinement through the Carpet driver.

  6. From wide to close binaries?

    NASA Astrophysics Data System (ADS)

    Eggleton, Peter P.

    The mechanisms by which the periods of wide binaries (mass 8 solar mass or less and period 10-3000 d) are lengthened or shortened are discussed, synthesizing the results of recent theoretical investigations. A system of nomenclature involving seven evolutionary states, three geometrical states, and 10 types of orbital-period evolution is developed and applied; classifications of 71 binaries are presented in a table along with the basic observational parameters. Evolutionary processes in wide binaries (single-star-type winds, magnetic braking with tidal friction, and companion-reinforced attrition), late case B systems, low-mass X-ray binaries, and triple systems are examined in detail, and possible evolutionary paths are shown in diagrams.

  7. Spectroscopy of Thorium Monoxide, ThO; E(O+),F(O+),-X 1Σ+ Bands

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Steimle, Timothy C.; Heaven, Michael

    2011-06-01

    Thorium monoxide, ThO, has recently attracted interest as a possible venue for the determination of the electric dipole moment of the electron, DE. Here we report on the results of an optical Stark study of the E(O+)-X1Σ+(1,0) band and the field-free study of the F(O+)-X1Σ+(0,0) band. A supersonic molecular beam of ThO was generated using a laser ablation technique and probed using laser excitation spectroscopy. The determined values for the permanent electric dipole moments, μEl, for the E(O+)(v=1) and X1Σ+(v=0) vibronic states were determined to be 3.534±0.010 D and 2.782±0.012 D, respectively. The dispersed laser induced fluorescence resulting from the excitation of the E(O+)-X1Σ+(1,0) and F(O+)-X1Σ+(0,0) bands have been recorded and the results are compared to Franck-Condon predictions. The radiative lifetimes for the E(O+)-X1Σ+(1,0) band F(O+)-X1Σ+(0,0) bands were determined. A. C. Vutha, W. C. Campbell, Y. V. Gurevich, N. R. Hutzler, M. Parsons, D. Patterson, E. Petrik, B. Spaun, J. M. Doyle, G. Gabrielse, and D. DeMille, J. Phys. B: At., Mol. Opt. Phys., 43, 074007/1 2010. G. Edvinsson and A. Lagerqvist, Physica Scripta, 32, 602, 1985. F. Wang, T. C. Steimle and M.C. Heaven, J. Chem. Phys.,{134

  8. Foreshocks and short-term hazard assessment of large earthquakes using complex networks: the case of the 2009 L'Aquila earthquake

    NASA Astrophysics Data System (ADS)

    Daskalaki, Eleni; Spiliotis, Konstantinos; Siettos, Constantinos; Minadakis, Georgios; Papadopoulos, Gerassimos A.

    2016-08-01

    The monitoring of statistical network properties could be useful for the short-term hazard assessment of the occurrence of mainshocks in the presence of foreshocks. Using successive connections between events acquired from the earthquake catalog of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) for the case of the L'Aquila (Italy) mainshock (Mw = 6.3) of 6 April 2009, we provide evidence that network measures, both global (average clustering coefficient, small-world index) and local (betweenness centrality) ones, could potentially be exploited for forecasting purposes both in time and space. Our results reveal statistically significant increases in the topological measures and a nucleation of the betweenness centrality around the location of the epicenter about 2 months before the mainshock. The results of the analysis are robust even when considering either large or off-centered the main event space windows.

  9. [The hazards of reconstruction: anthropology of dwelling and social health risk in the L'Aquila (Central Italy) post-earthquake].

    PubMed

    Ciccozzi, Antonello

    2016-01-01

    Even starting from the purpose of restoring the damage caused by a natural disaster, the post-earthquake reconstructions imply the risk of triggering a set of social disasters that may affect the public health sphere. In the case of the L'Aquila earthquake this risk seems to emerge within the urban planning on two levels of dwelling: at a landscape level, where there has been a change in the shape of the city towards a sprawling-sprinkling process; at an architectural level, on the problematic relationship between the politics and the poetics of cultural heritage protection and the goal to get restoration works capable to ensure the citizens seismic safety. PMID:27291216

  10. Gravity driven and tectonic post-seismic deformation of the April 6 2009 L'Aquila Earthquake detected by Cosmo-SkyMed DInSAR

    NASA Astrophysics Data System (ADS)

    Moro, M.; Albano, M.; Bignami, C.; Malvarosa, F.; Costantini, M.; Saroli, M.; Barba, S.; Falco, S.; Stramondo, S.

    2014-12-01

    The present work focuses on the analysis of post-seismic surface deformation detected in the area of L'Aquila, Central Italy, after the strong earthquake that hit the city and the surrounding villages on April 6th, 2009. The analysis has been carried out thanks to a new dataset of SAR COSMO-SkyMed images covering a time span of 480 days after the mainshock, with the adoption of the Persistent Scatterer Pairs (PSP) approach. This method allows the estimation of surface deformations by exploiting the SAR images at full resolution. In the investigated area two patterns of subsidence have been identified reaching a maximum value of 45 mm in the northeast area of the L'Aquila town. Here the subsidence is mainly ascribable to the post seismic slip release of the Paganica fault and it does not coincide with the maximum measured coseismic subsidence. The time series of the ground deformations also reveal that a large amount of deformation is released in the first three months after the main shock. The second pattern of deformation is centered on the Mt. Ocre ridge, where a detailed photogeological analysis allowed us to identify widespread evidence of morphological elements associated with Deep-seated gravitational slope deformation (DGSD). In particular geomorphologic analyses show evidences of lateral spread DGSD-type features, characterized by the tectonic superimposition of carbonatic sequences and transitional pelagic deposits. In this sector, the observed deformation is ascribable not only to the afterslip of the Paganica fault, but also to a gravitative cause. In order to confirm or reject such hypothesis a 2D numerical finite element models considering two cross sections over the Mt. Ocre ridge has been performed. The coseismic and postseimic deformations have been simulated numerically, considering an elastic-perfectly plastic rheology for the constituent rocks. First results show that most of the postseismic deformation is ascribable to the plastic deformation

  11. Physiological role for P2X1 receptors in renal microvascular autoregulatory behavior

    PubMed Central

    Inscho, Edward W.; Cook, Anthony K.; Imig, John D.; Vial, Catherine; Evans, Richard J.

    2003-01-01

    This study tests the hypothesis that P2X1 receptors mediate pressure-induced afferent arteriolar autoregulatory responses. Afferent arterioles from rats and P2X1 KO mice were examined using the juxtamedullary nephron technique. Arteriolar diameter was measured in response to step increases in renal perfusion pressure (RPP). Autoregulatory adjustments in diameter were measured before and during P2X receptor blockade with NF279 or A1 receptor blockade with 1,3-dipropyl-8-cyclopentylxanthine (DPCPX). Acute papillectomy or furosemide perfusion was performed to interrupt distal tubular fluid flow past the macula densa, thus minimizing tubuloglomerular feedback–dependent influences on afferent arteriolar function. Under control conditions, arteriolar diameter decreased by 17% and 29% at RPP of 130 and 160 mmHg, respectively. Blockade of P2X1 receptors with NF279 blocked pressure-mediated vasoconstriction, reflecting an attenuated autoregulatory response. The A1 receptor blocker DPCPX did not alter autoregulatory behavior or the response to ATP. Deletion of P2X1 receptors in KO mice significantly blunted autoregulatory responses induced by an increase in RPP, and this response was not further impaired by papillectomy or furosemide. WT control mice exhibited typical RPP-dependent vasoconstriction that was significantly attenuated by papillectomy. These data provide compelling new evidence indicating that tubuloglomerular feedback signals are coupled to autoregulatory preglomerular vasoconstriction through ATP-mediated activation of P2X1 receptors. PMID:14679185

  12. Correlations between X-Ray Spectral Characteristics and Quasi-Periodic Oscillations in Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Bradshaw, Charles F.; Titarchuk, Lev; Kuznetsov, Sergey

    2007-07-01

    Correlations between 1-10 Hz quasi-periodic oscillations (QPOs) and spectral power-law index have been reported for black hole (BH) candidate sources and one neutron star source, 4U 1728-34. An examination of QPO frequency and index relationships in Sco X-1 is reported here. We discover that Sco X-1, representing Z-source groups, can be adequately modeled by a simple two-component model of Compton up-scattering with a soft photon electron temperature of about 0.4 keV, plus an Iron K line. The results show a strong correlation between spectral power-law index and kHz QPOs. Because Sco X-1 radiates near the Eddington limit, one can infer that the geometrical configuration of the Compton cloud (CC) is quasi-spherical from high radiation pressure in the CC. Thus, we conclude that the high Thomson optical depth of the Compton cloud, in the range of ~5-6 from the best-fit model parameters, is consistent with the neutron star's surface being obscured by material. Moreover, a spin frequency of Sco X-1 is likely suppressed due to photon scattering off CC electrons. In addition, we demonstrate how the power spectrum evolves when Sco X-1 transitions from the horizontal branch to the normal branch.

  13. A LIKELY MICRO-QUASAR IN THE SHADOW OF M82 X-1

    SciTech Connect

    Xu, Xiao-jie; Liu, Jifeng; Liu, Jiren E-mail: jfliu@nao.cas.cn

    2015-02-01

    The ultra-luminous X-ray source M82 X-1 is one of the most promising intermediate mass black hole candidates in the local universe based on its high X-ray luminosities (10{sup 40}–10{sup 41} erg s{sup −1}) and quasi-periodic oscillations, and is possibly associated with a radio flare source. In this work, applying the sub-pixel technique to the 120 ks Chandra observation (ID: 10543) of M82 X-1, we split M82 X-1 into two sources separated by 1.″1. The secondary source is not detected in other M82 observations. The radio flare source is not found to associate with M82 X-1, but is instead associated with the nearby transient source S1 with an outburst luminosity of ∼10{sup 39} erg s{sup −1}. With X-ray outburst and radio flare activities analogous to the recently discovered micro-quasar in M31, S1 is likely to be a micro-quasar hidden in the shadow of M82 X-1.

  14. A Likely Micro-Quasar in the Shadow of M82 X-1

    NASA Astrophysics Data System (ADS)

    Xu, Xiao-jie; Liu, Jifeng; Liu, Jiren

    2015-02-01

    The ultra-luminous X-ray source M82 X-1 is one of the most promising intermediate mass black hole candidates in the local universe based on its high X-ray luminosities (1040-1041 erg s-1) and quasi-periodic oscillations, and is possibly associated with a radio flare source. In this work, applying the sub-pixel technique to the 120 ks Chandra observation (ID: 10543) of M82 X-1, we split M82 X-1 into two sources separated by 1.″1. The secondary source is not detected in other M82 observations. The radio flare source is not found to associate with M82 X-1, but is instead associated with the nearby transient source S1 with an outburst luminosity of ˜1039 erg s-1. With X-ray outburst and radio flare activities analogous to the recently discovered micro-quasar in M31, S1 is likely to be a micro-quasar hidden in the shadow of M82 X-1.

  15. Chandra X-ray Spectroscopy of the Focused Wind In the Cygnus X-1 System I. The Non-Dip Spectrum in the Low/Hard State

    NASA Technical Reports Server (NTRS)

    Hanke, Manfred; Wilms, Jorn; Nowak, Michael A.; Pottschmidt, Katja; Schultz, Norbert S.; Lee, Julia C.

    2008-01-01

    We present analyses of a 50 ks observation of the supergiant X-ray binary system CygnusX-1/HDE226868 taken with the Chandra High Energy Transmission Grating Spectrometer (HETGS). CygX-1 was in its spectrally hard state and the observation was performed during superior conjunction of the black hole, allowing for the spectroscopic analysis of the accreted stellar wind along the line of sight. A significant part of the observation covers X-ray dips as commonly observed for CygX-1 at this orbital phase, however, here we only analyze the high count rate non-dip spectrum. The full 0.5-10 keV continuum can be described by a single model consisting of a disk, a narrow and a relativistically broadened Fe K line, and a power law component, which is consistent with simultaneous RXTE broad band data. We detect absorption edges from overabundant neutral O, Ne and Fe, and absorption line series from highly ionized ions and infer column densities and Doppler shifts. With emission lines of He-like Mg XI, we detect two plasma components with velocities and densities consistent with the base of the spherical wind and a focused wind. A simple simulation of the photoionization zone suggests that large parts of the spherical wind outside of the focused stream are completely ionized, which is consistent with the low velocities (<200 km/s) observed in the absorption lines, as the position of absorbers in a spherical wind at low projected velocity is well constrained. Our observations provide input for models that couple the wind activity of HDE 226868 to the properties of the accretion flow onto the black hole.

  16. Kepler K2 Observations of Sco X-1: Orbital Modulations and Correlations with Fermi GBM and MAXI

    NASA Astrophysics Data System (ADS)

    Hynes, Robert I.; Schaefer, Bradley E.; Baum, Zachary A.; Hsu, Ching-Cheng; Cherry, Michael L.; Scaringi, Simone

    2016-04-01

    We present a multi-wavelength study of the low-mass X-ray binary Sco X-1 using Kepler K2 optical data and Fermi GBM and MAXI X-ray data. We recover a clear sinusoidal orbital modulation from the Kepler data. Optical fluxes are distributed bimodally around the mean orbital light curve, with both high and low states showing the same modulation. The high state is broadly consistent with the flaring branch of the Z diagram and the low state with the normal branch. We see both rapid optical flares and slower dips in the high state, and slow brightenings in the low state. High state flares exhibit a narrow range of amplitudes with a striking cut-off at a maximum amplitude. Optical fluxes correlate with X-ray fluxes in the high state, but in the low state they are anti-correlated. These patterns can be seen clearly in both flux-flux diagrams and cross-correlation functions and are consistent between MAXI and GBM. The high state correlation arises promptly with at most a few minutes lag. We attribute this to thermal reprocessing of X-ray flares. The low state anti-correlation is broader, consistent with optical lags of between zero and 30 min, and strongest with respect to high energy X-rays. We suggest that the decreases in optical flux in the low state may reflect decreasing efficiency of disc irradiation, caused by changes in the illumination geometry. These changes could reflect the vertical extent or covering factor of obscuration or the optical depth of scattering material.

  17. Kepler K2 observations of Sco X-1: orbital modulations and correlations with Fermi GBM and MAXI

    NASA Astrophysics Data System (ADS)

    Hynes, Robert I.; Schaefer, Bradley E.; Baum, Zachary A.; Hsu, Ching-Cheng; Cherry, Michael L.; Scaringi, Simone

    2016-07-01

    We present a multi-wavelength study of the low-mass X-ray binary Sco X-1 using Kepler K2 optical data and Fermi GBM and MAXI X-ray data. We recover a clear sinusoidal orbital modulation from the Kepler data. Optical fluxes are distributed bimodally around the mean orbital light curve, with both high and low states showing the same modulation. The high state is broadly consistent with the flaring branch of the Z-diagram and the low state with the normal branch. We see both rapid optical flares and slower dips in the high state, and slow brightenings in the low state. High-state flares exhibit a narrow range of amplitudes with a striking cut-off at a maximum amplitude. Optical fluxes correlate with X-ray fluxes in the high state, but in the low state they are anti-correlated. These patterns can be seen clearly in both flux-flux diagrams and cross-correlation functions and are consistent between MAXI and GBM. The high-state correlation arises promptly with at most a few minutes lag. We attribute this to thermal reprocessing of X-ray flares. The low-state anti-correlation is broader, consistent with optical lags of between zero and 30 min, and strongest with respect to high-energy X-rays. We suggest that the decreases in optical flux in the low state may reflect decreasing efficiency of disc irradiation, caused by changes in the illumination geometry. These changes could reflect the vertical extent or covering factor of obscuration or the optical depth of scattering material.

  18. M82 X-1 ---The Hyper Luminous X-Ray Source---

    NASA Astrophysics Data System (ADS)

    Tsuru, T. G.; Matsumoto, H.; Inui, T.; Matsushita, S.; Kawabe, R.; Harashima, T.; Maihara, T.; Iwamuro, F.

    By using ASCA and Chandra, we discovered a bright X-ray source M82 X-1 in the starburst galaxy M82. The peak luminosity of ˜ 1× 1041 ergs sec-1 and the location of off-center position of M82 in the starburst galaxy M82 suggest that M82 X-1 is a new type of black hole, intermediate massive black hole (IMBH). We also found an expanding molecular super bubble (EMSB) surrounding the IMBH. We propose a hypothesis that the IMBH was formed in the starburst activity 10^6˜ 10^7 yrs ago. We review the course of the discovery and show recent progress on studies of the X-ray spectrum and the position of M82 X-1.

  19. Systems analysis and engineering of the X-1 Advanced Radiation Source

    SciTech Connect

    Rochau, G.E.; Hands, J.A.; Raglin, P.S.; Ramirez, J.J.

    1998-10-01

    The X-1 Advanced Radiation Source, which will produce {approximately} 16 MJ in x-rays, represents the next step in providing US Department of Energy`s Stockpile Stewardship program with the high-energy, large volume, laboratory x-ray sources needed for the Radiation Effects Science and Simulation (RES), Inertial Confinement Fusion (ICF), and Weapon Physics (WP) Programs. Advances in fast pulsed power technology and in z-pinch hohlraums on Sandia National Laboratories` Z Accelerator in 1997 provide sufficient basis for pursuing the development of X-1. This paper will introduce the X-1 Advanced Radiation Source Facility Project, describe the systems analysis and engineering approach being used, and identify critical technology areas being researched.

  20. Long-Term Evolution of the Correlated Spectral and Timing Properties of CIR X-1

    NASA Astrophysics Data System (ADS)

    Shirey, Robert

    Our previous RXTE results demonstrate that at the baseline intensity level of 1.0 Crab, Cir X-1 exhibits Z-source behavior, but with QPOs which shift to lower than usual frequencies. In contrast, EXOSAT observations at lower baseline intensity showed behavior that resembled that of atoll sources. Recent RXTE ASM observations show that the baseline intensity of Cir X-1 has decreased to below 750 mCrab in the most recent few 16.55-d cycles. In order to monitor the evolution of the timing and spectral properties of Cir X-1 and to search for type-1 bursts as its baseline intensity evolves, we propose observations at several intensity trigger levels. We also propose observations if radio flares (which are now faint) return to the high intensities of the 1970's and early 1980's.

  1. Evolution of the Correlated Spectral and Timing Properties of Circinus X-1

    NASA Astrophysics Data System (ADS)

    Shirey, Robert

    Circinus X-1 has maintained a bright 1-Crab baseline during the entire RXTE mission to date, and shows absorption dips and flares near phase zero of its 16.55-d orbital cycle. Our recent RXTE PCA results demonstrate that Cir X-1 currently exhibits Z-source behavior, i.e., 1.3-35 Hz QPOs on the horizontal branch, a 4-Hz QPO on the normal branch, and only VLFN on the flaring branch. However, EXOSAT observations at lower intensity showed behavior that resembled that of atoll sources. In order to search for such an unprecedented switch in behavior, we propose TOO observations of Cir X-1 if the baseline intensity level returns to the previously observed low levels. We also propose observations if radio flares (which are now faint), return to the high intensities of the 1970s and early 1980s.

  2. Scaling of the F_2 structure function in nuclei and quark distributions at x>1

    SciTech Connect

    Fomin, N; Arrington, J; Gaskell, D; Daniel, A; Seely, J; Asaturyan, R; Benmokhtar, F; Boeglin, W; Boillat, B; Bosted, P; Bruell, A; Bukhari, M.H.S.; Christy, M E; Chudakov, E; Clasie, B; Connell, S H; Dalton, M M; Dutta, D; Ent, R; El Fassi, L; Fenker, H; Filippone, B W; Garrow, K; Hill, C; Holt, R J; Horn, T; Jones, M K; Jourdan, J; Kalantarians, N; Keppel, C E; Kiselev, D; Kotulla, M; Lindgren, R; Lung, A F; Malace, S; Markowitz, P; McKee, P; Meekins, D G; Miyoshi, T; Mkrtchyan, H; Navasardyan, T; Niculescu, G; Okayasu, Y; Opper, A K; Perdrisat, C; Potterveld, D H; Punjabi, V; Qian, X; Reimer, P E; Roche, J; Rodriguez, V M; Rondon, O; Schulte, E; Segbefia, E; Slifer, K; Smith, G R; Solvignon, P; Tadevosyan, V; Tajima, S; Tang, L; Testa, G; Tvaskis, V; Vulcan, W F; Wasko, C; Wesselmann, F R; Wood, S A; Wright, J; Zheng, X

    2010-11-01

    We present new data on electron scattering from a range of nuclei taken in Hall C at Jefferson Lab. For heavy nuclei, we observe a rapid falloff in the cross section for $x>1$, which is sensitive to short range contributions to the nuclear wave-function, and in deep inelastic scattering corresponds to probing extremely high momentum quarks. This result agrees with higher energy muon scattering measurements, but is in sharp contrast to neutrino scattering measurements which suggested a dramatic enhancement in the distribution of the `super-fast' quarks probed at x>1. The falloff at x>1 is noticeably stronger in ^2H and ^3He, but nearly identical for all heavier nuclei.

  3. Planets in Evolved Binary Systems

    NASA Astrophysics Data System (ADS)

    Perets, Hagai B.

    2011-03-01

    Exo-planets are typically thought to form in protoplanetary disks left over from protostellar disk of their newly formed host star. However, additional planetary formation and evolution routes may exist in old evolved binary systems. Here we discuss the implications of binary stellar evolution on planetary systems in such environments. In these binary systems stellar evolution could lead to the formation of symbiotic stars, where mass is lost from one star and could be transferred to its binary companion, and may form an accretion disk around it. This raises the possibility that such a disk could provide the necessary environment for the formation of a new, second generation of planets in both circumstellar or circumbinary configurations. Pre-existing first generation planets surviving the post-MS evolution of such systems would be dynamically effected by the mass loss in the systems and may also interact with the newly formed disk. Such planets and/or planetesimals may also serve as seeds for the formation of the second generation planets, and/or interact with them, possibly forming atypical planetary systems. Second generation planetary systems should be typically found in white dwarf binary systems, and may show various observational signatures. Most notably, second generation planets could form in environment which are inaccessible, or less favorable, for first generation planets. The orbital phase space available for the second generation planets could be forbidden (in terms of the system stability) to first generation planets in the pre-evolved progenitor binaries. In addition planets could form in metal poor environments such as globular clusters and/or in double compact object binaries. Observations of exo-planets in such forbidden or unfavorable regions could possibly serve to uniquely identify their second generation character. Finally, we point out a few observed candidate second generation planetary systems, including Gl 86, HD 27442 and all of the

  4. The Behavior of the Optical and X-Ray Emission from Scorpius X-1

    NASA Astrophysics Data System (ADS)

    McNamara, B. J.; Harrison, T. E.; Zavala, R. T.; Galvan, Eduardo; Galvan, Javier; Jarvis, T.; Killgore, GeeAnn; Mireles, O. R.; Olivares, D.; Rodriquez, B. A.; Sanchez, M.; Silva, Allison L.; Silva, Andrea L.; Silva-Velarde, E.; Templeton, M. R.

    2003-03-01

    In 1970, Hiltner & Mook reported the results of the first multiyear study of the optical emission from Sco X-1. They found that the Sco X-1 B-magnitude histograms changed from year to year. Subsequent multiwavelength campaigns confirmed the variable nature of these optical histograms and also found that the X-ray and optical emissions were only correlated when Sco X-1 was brighter than about B=12.6. Models had suggested that the optical emission from this source arose from X-rays reprocessed in an accretion disk surrounding the central neutron star. It was therefore difficult to explain why the optical and X-ray fluxes were not more closely correlated. In 1994 and 1995, two new simultaneous optical and X-ray campaigns on Sco X-1 were conducted with the Burst and Transient Source Experiment on the Compton Gamma Ray Observatory and the 1 m Yale telescope at Cerro Tololo Inter-American Observatory. Using these data and models by Psaltis, Lamb, & Miller, it is now possible to provide a qualitative picture of how the X-ray and optical emissions from Sco X-1 are related. Differences in the B-magnitude histograms are caused by variations in the mass accretion rate and the relatively short time period typically covered by optical investigations. The tilted-Γ pattern seen in plots of the simultaneous X-ray and optical emission from Sco X-1 arises from (1) the nearly linear relation between the optical B magnitude and the mass accretion rate in the range 13.3>=B>=12.3 and an asymptotic behavior in the B magnitude outside this range, and (2) a double-valued relation between the X-ray emission and mass accretion rate along the normal branch and lower flaring branch of this source.

  5. Purinergic control of inflammation and thrombosis: Role of P2X1 receptors

    PubMed Central

    Oury, Cécile; Lecut, Christelle; Hego, Alexandre; Wéra, Odile; Delierneux, Céline

    2014-01-01

    Inflammation shifts the hemostatic mechanisms in favor of thrombosis. Upon tissue damage or infection, a sudden increase of extracellular ATP occurs, that might contribute to the crosstalk between inflammation and thrombosis. On platelets, P2X1 receptors act to amplify platelet activation and aggregation induced by other platelet agonists. These receptors critically contribute to thrombus stability in small arteries. Besides platelets, studies by our group indicate that these receptors are expressed by neutrophils. They promote neutrophil chemotaxis, both in vitro and in vivo. In a laser-induced injury mouse model of thrombosis, it appears that neutrophils are required to initiate thrombus formation and coagulation activation on inflamed arteriolar endothelia. In this model, by using P2X1−/ − mice, we recently showed that P2X1 receptors, expressed on platelets and neutrophils, play a key role in thrombus growth and fibrin generation. Intriguingly, in a model of endotoxemia, P2X1−/ − mice exhibited aggravated oxidative tissue damage, along with exacerbated thrombocytopenia and increased activation of coagulation, which translated into higher susceptibility to septic shock. Thus, besides its ability to recruit neutrophils and platelets on inflamed endothelia, the P2X1 receptor also contributes to limit the activation of circulating neutrophils under systemic inflammatory conditions. Taken together, these data suggest that P2X1 receptors are involved in the interplay between platelets, neutrophils and thrombosis. We propose that activation of these receptors by ATP on neutrophils and platelets represents a new mechanism that regulates thrombo-inflammation. PMID:25709760

  6. On the distance to Cygnus X-1. [extrapolation from nearby stars

    NASA Technical Reports Server (NTRS)

    Margon, B.; Bowyer, S.; Stone, R. P. S.

    1973-01-01

    Interstellar extinction of 50 stars in the immediate vicinity of Cyg X-1 is compared with color excess of HDE 226868. The fact that HDE 226868 has extinction drastically exceeding that of all stars in the field at less than 1 kpc is believed to be in conflict with the model of Trimble et al. (1973) in which the primary is a luminous undermassive star and with other similar models. Uniform extrapolation of the reddening yields a distance estimate of (2.5 plus or minus 0.4) kpc for Cygnus X-1, in agreement