Spectroscopy of the nova candidate M31-2008-10b

NASA Astrophysics Data System (ADS)

Di Mille, F.; Ciroi, S.; Orio, M.; Rafanelli, P.; Bianchini, A.; Nelson, T.; Andreuzzi, G.

2008-10-01

We obtained a low resolution spectrum of the nova candidate M31-2008-10b ( see CBAT M31 nova page) on 2008 October 26.12 UT. The observations were performed with TNG + DOLORES spectrograph 20 days after the first detection (see Atel #1790 ). The spectrum (in the 330-790 nm range, with resolution 1 nm) shows strong Balmer lines superimposed on a flat continuum.

Fermi-LAT Gamma-Ray Detections of Classical Novae V1369 Centauri 2013 and V5668 Sagittarii 2015

NASA Astrophysics Data System (ADS)

Cheung, C. C.; Jean, P.; Shore, S. N.; Stawarz, Ł.; Corbet, R. H. D.; Knödlseder, J.; Starrfield, S.; Wood, D. L.; Desiante, R.; Longo, F.; Pivato, G.; Wood, K. S.

2016-08-01

We report the Fermi Large Area Telescope (LAT) detections of high-energy (>100 MeV) γ-ray emission from two recent optically bright classical novae, V1369 Centauri 2013 and V5668 Sagittarii 2015. At early times, Fermi target-of-opportunity observations prompted by their optical discoveries provided enhanced LAT exposure that enabled the detections of γ-ray onsets beginning ˜2 days after their first optical peaks. Significant γ-ray emission was found extending to 39-55 days after their initial LAT detections, with systematically fainter and longer-duration emission compared to previous γ-ray-detected classical novae. These novae were distinguished by multiple bright optical peaks that encompassed the time spans of the observed γ-rays. The γ-ray light curves and spectra of the two novae are presented along with representative hadronic and leptonic models, and comparisons with other novae detected by the LAT are discussed.

Photometric Investigation of Novae T Pyx, BT Mon and V574 Pup at Quiescence by using the 2.4-m Thai National Telescope

NASA Astrophysics Data System (ADS)

Thipboon, Ritthichai; Kaewrakmuk, Metichai; Surina, Farung; Sanguansak, Nuanwan

2017-09-01

Recurrent novae (RNe) are novae with multiple recorded outbursts powered by a thermonuclear runaway. The outburst occurs on the surface of the white dwarf which accompanies with a late type main-sequence or giant secondary star transferring material onto the white dwarf primary star. They resemble classical novae (CNe) outbursts but only RNe has more than one recorded outbursts. RNe play an important role as one of the suspected progenitor systems of Type Ia supernovae (SNe) which are used as primary distance indicators in cosmology. Thus, it is important to investigate the outburst type of CNe and RNe and finally ascertain the population of objects that might ultimately be candidates for Type Ia SNe explosions. The proposal that RNe occupy a region separated from CNe in an outburst amplitude versus speed class diagram was adopted. Since the low amplitude results from the existence of an evolved secondary and/or high mass transfer rate in the quiescent system, RNe candidates should accordingly have low amplitude. We selected 3 preliminary targets including T Pyx, BT Mon and V574 Pup. Their amplitudes are not that low but the lowest amplitude that can be observed with Thai National Telescope (TNT). We obtained their magnitudes at quiescence using ULTRASPEC camera on the 2.4-m TNT. The positions of three targets on optical and near-infrared color-magnitude diagrams suggest that all three should have main-sequence secondary stars. This is true for T Pyx, whose secondary star has been confirmed its spectroscopy to be a main-sequence star, but not yet confirmed for BT Mon and V574 Pup.

Fermi-LAT gamma ray detections of classical novae V1369 centauri 2013 and V5668 Sagittarii 2015

DOE PAGES

Cheung, C. C.; Jean, P.; Shore, S. N.; ...

2016-07-27

Here, we report the Fermi Large Area Telescope (LAT) detections of high-energy (>100 MeV) γ-ray emission from two recent optically bright classical novae, V1369 Centauri 2013 and V5668 Sagittarii 2015. Furthermore, at early times, Fermi target-of-opportunity observations prompted by their optical discoveries provided enhanced LAT exposure that enabled the detections of γ-ray onsets beginning ~2 days after their first optical peaks. Significant γ-ray emission was found extending to 39–55 days after their initial LAT detections, with systematically fainter and longer-duration emission compared to previous γ-ray-detected classical novae. These novae were distinguished by multiple bright optical peaks that encompassed the timemore » spans of the observed γ-rays. Finally, we discussed the γ-ray light curves and spectra of the two novae are presented along with representative hadronic and leptonic models, and comparisons with other novae detected by the LAT.« less

Search for Gamma-Ray Emission from Galactic Novae using Fermi-LAT Pass 8

NASA Astrophysics Data System (ADS)

Buson, Sara; Franckowiak, Anna; Cheung, Teddy; Jean, Pierre; Fermi-LAT Collaboration

2016-01-01

Recently Galactic novae have been identified as a new class of GeV gamma-ray emitters, with 6 detected so far with the Fermi Large Area Telescope (Fermi-LAT) data. Based on optical observations we have compiled a catalog of ~70 Galactic novae, which peak (in optical) during the operations of the Fermi mission. Based on the properties of known gamma-ray novae we developed a search procedure that we apply to all novae in the catalog to detect these slow transient sources or set flux upper limits using the Fermi-LAT Pass 8 data set. This is the first time a large sample of Galactic novae has been uniformly studied.

One Thousand New Dwarf Novae from the OGLE Survey

NASA Astrophysics Data System (ADS)

Mróz, P.; Udalski, A.; Poleski, R.; Pietrukowicz, P.; Szymański, M. K.; Soszyński, I.; Wyrzykowski, Ł.; Ulaczyk, K.; Kozłowski, S.; Skowron, J.

2015-12-01

We present one of the largest collections of dwarf novae (DNe) containing 1091 objects that have been discovered in the long-term photometric data from the Optical Gravitational Lensing Experiment (OGLE) survey. They were found in the OGLE fields toward the Galactic bulge and the Magellanic Clouds. We analyze basic photometric properties of all systems and tentatively find a population of DNe from the Galactic bulge. We identify several dozen of WZ Sge-type DN candidates, including two with superhump periods longer than 0.09 d. Other interesting objects include SU UMa-type stars with "early" precursor outbursts or a Z Cam-type star showing outbursts during standstills. We also provide a list of DNe which will be observed during the K2 Campaign 9 microlensing experiment in 2016. Finally, we present the new OGLE-IV real-time data analysis system: CVOM, which has been designed to provide continuous real time photometric monitoring of selected CVs.

Optical and Near-infrared Study of Nova V2676 Oph 2012

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raj, A.; Das, R. K.; Walter, F. M., E-mail: ashish.raj@iiap.res.in

2017-02-01

We present optical spectrophotometric and near-infrared (NIR) photometric observations of the nova V2676 Oph covering the period from 2012 March 29 through 2015 May 8. The optical spectra and photometry of the nova have been taken from SMARTS and Asiago; the NIR photometry was obtained from SMARTS and Mt. Abu. The spectra were dominated by strong H i lines from the Balmer series, Fe ii, N i, and [O i] lines in the initial days, typical of an Fe ii type nova. The measured FWHM for the H β and H α lines was 800–1200 km s{sup −1}. There wasmore » pronounced dust formation starting 90 days after the outburst. The J − K color was the largest among recent dust-forming novae.« less

Magnetic novae

NASA Astrophysics Data System (ADS)

Zemko, Polina; Orio, Marina

2016-07-01

We present the results of optical and X-ray observations of two quiescent novae, V2491 Cyg and V4743 Sgr. Our observations suggest the intriguing possibility of localization of hydrogen burning in magnetic novae, in which accretion is streamed to the polar caps. V2491 Cyg was observed with Suzaku more than 2 years after the outburst and V4743 Sgr was observed with XMM Newton 2 and 3.5 years after maximum. In the framework of a monitoring program of novae previously observed as super soft X-ray sources we also obtained optical spectra of V4743 Sgr with the SALT telescope 11.5 years after the eruption and of V2491 Cyg with the 6m Big Azimutal Telescope 4 and 7 years post-outburst. In order to confirm the possible white dwarf spin period of V2491 Cyg measured in the Suzaku observations we obtained photometric data using the 90cm WIYN telescope at Kitt Peak and the 1.2 m telescope in Crimea. We found that V4743 Sgr is an intermediate polar (IP) and V2491 Cyg is a strong IP candidate. Both novae show modulation of their X-ray light curves and have X-ray spectra typical of IPs. The Suzaku and XMM Newton exposures revealed that the spectra of both novae have a very soft blackbody-like component with a temperature close to that of the hydrogen burning white dwarfs in their SSS phases, but with flux by at least two orders of magnitude lower, implying a possible shrinking of emitting regions in the thin atmosphere that is heated by nuclear burning underneath it. In quiescent IPs, independently of the burning, an ultrasoft X-ray flux component originates at times in the polar regions irradiated by the accretion column, but the soft component of V4743 Sgr disappeared in 2006, indicating that the origin may be different from accretion. We suggest it may have been due to an atmospheric temperature gradient on the white dwarf surface, or to continuing localized thermonuclear burning at the bottom of the envelope, before complete turn-off. The optical spectra of V2491 Cyg and V4743 Sgr showed the prominent He II 4686 A line and the Bowen blend, which indicate a hot region, with peak temperature in the ultraviolet range. This may be the same region that previously emitted supersoft X-rays, and later cooled shifting the peak of emission to the ultraviolet.

A UNIVERSAL DECLINE LAW OF CLASSICAL NOVAE. IV. V838 HER (1991): A VERY MASSIVE WHITE DWARF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kato, Mariko; Hachisu, Izumi; Cassatella, Angelo, E-mail: mariko@educ.cc.keio.ac.j, E-mail: hachisu@ea.c.u-tokyo.ac.j, E-mail: cassatella@fis.uniroma3.i

2009-10-20

We present a unified model of optical and ultraviolet (UV) light curves for one of the fastest classical novae, V838 Herculis (Nova Herculis 1991), and estimate its white dwarf (WD) mass. Based on an optically thick wind theory of nova outbursts, we model the optical light curves with free-free emission and the UV 1455 A light curves with blackbody emission. Our models of 1.35 +- 0.02 M {sub sun} WD simultaneously reproduce the optical and UV 1455 A observations. The mass lost by the wind is DELTAM {sub wind} approx 2 x 10{sup -6} M {sub sun}. We provide newmore » determinations of the reddening, E(B - V) = 0.53 +- 0.05, and of the distance, 2.7 +- 0.5 kpc.« less

Bright Merger-nova Emission Powered by Magnetic Wind from a Newborn Black Hole

NASA Astrophysics Data System (ADS)

Ma, Shuai-Bing; Lei, Wei-Hua; Gao, He; Xie, Wei; Chen, Wei; Zhang, Bing; Wang, Ding-Xiong

2018-01-01

Mergers of neutron star–neutron star (NS–NS) or neutron star–black hole (NS–BH) binaries are candidate sources of gravitational waves (GWs). At least a fraction of the merger remnants should be a stellar mass BH with sub-relativistic ejecta. A collimated jet is launched via the Blandford–Znajek mechanism from the central BH to trigger a short gamma-ray burst (sGRB). At the same time, a near-isotropic wind may be driven by the Blandford–Payne mechanism (BP). In previous work, additional energy injection to the ejecta from the BP mechanism was ignored, and radioactive decay has long been thought to be the main source of the kilonova energy. In this Letter, we propose that the wind driven by the BP mechanism from the newborn BH’s disk can heat up and push the ejecta during the prompt emission phase or even at late times when there is fall-back accretion. Such a BP-powered merger-nova could be bright in the optical band even for a low-luminosity sGRB. The detection of a GW merger event with a BH clearly identified as a remnant, accompanied by a bright merger-nova, would provide robust confirmation of our model.

Non-LTE model atmosphere analysis of Nova Cygni 1992

NASA Technical Reports Server (NTRS)

Hauschildt, P. H.; Starrfield, S.; Austin, S.; Wagner, R. M.; Shore, S. N.; Sonneborn, G.

1994-01-01

We use spherically symmetric non-local thermodynamic equilibrium (non-LTE), line-blanketed, expanding model atmospheres to analyze the International Ultraviolet Explorer (IUE) and optical spectra of Nova Cygni 1992 during the early phases of its outburst. We find that the first IUE spectrum obtained just after discovery on 1992 February 20, is best reproduced by a model atmosphere with a steep density gradient and homologous expansion, whereas the IUE and optical spectra obtained on February 24 show an extended, optically thick, wind structure. Therefore, we distinguish two phases of the early evolution of the nova photosphere: the initial, rapid, 'fireball' phase and the subsequent, much longer, optically thick 'wind' phase. The importance of line-blanketing in nova spectra is demonstrated. Our preliminary abundance analysis implies that hydrogen is depeleted in the ejecta, corresponding to abundance enhancements of Fe by a factor of approximately 2 and of CNO by more than a factor of 10 when compared to solar abundances. The synthetic spectra reproduce both the observed pseudo-continua as well as most of the observed features from the UV to the optical spectral range and demonstrate the importance of obtaining nearly simultaneous UV and optical spectra for performing accurate analyses of expanding stellar atmospheres (for both novae and supernovae).

Multiwavelength observations of nova SMCN 2016-10a - one of the brightest novae ever observed

NASA Astrophysics Data System (ADS)

Aydi, E.; Page, K. L.; Kuin, N. P. M.; Darnley, M. J.; Walter, F. M.; Mróz, P.; Buckley, D. A. H.; Mohamed, S.; Whitelock, P.; Woudt, P.; Williams, S. C.; Orio, M.; Williams, R. E.; Beardmore, A. P.; Osborne, J. P.; Kniazev, A.; Ribeiro, V. A. R. M.; Udalski, A.; Strader, J.; Chomiuk, L.

2018-02-01

We report on multiwavelength observations of nova Small Magellanic Cloud Nova 2016-10a. The present observational set is one of the most comprehensive for any nova in the Small Magellanic Cloud, including low-, medium-, and high-resolution optical spectroscopy and spectropolarimetry from Southern African Large Telescope, Folded Low-Order Yte-Pupil Double-Dispersed Spectrograph, and Southern Astrophysical Research; long-term Optical Gravitational Lensing Experiment V- and I-bands photometry dating back to 6 yr before eruption; Small and Moderate Aperture Research Telescope System optical and near-IR photometry from ˜11 d until over 280 d post-eruption; Swift satellite X-ray and ultraviolet observations from ˜6 d until 319 d post-eruption. The progenitor system contains a bright disc and a main sequence or a sub-giant secondary. The nova is very fast with t2 ≃ 4.0 ± 1.0 d and t3 ≃ 7.8 ± 2.0 d in the V band. If the nova is in the SMC, at a distance of ˜61 ± 10 kpc, we derive MV, max ≃ -10.5 ± 0.5, making it the brightest nova ever discovered in the SMC and one of the brightest on record. At day 5 post-eruption the spectral lines show a He/N spectroscopic class and an Full Width at Half Maximum of ˜3500 km s-1, indicating moderately high ejection velocities. The nova entered the nebular phase ˜20 d post-eruption, predicting the imminent super-soft source turn-on in the X-rays, which started ˜28 d post-eruption. The super-soft source properties indicate a white dwarf mass between 1.2 and 1.3 M⊙ in good agreement with the optical conclusions.

Follow-up Observations of SDSS and CRTS Candidate Cataclysmic Variables II

NASA Astrophysics Data System (ADS)

Szkody, Paula; Everett, Mark E.; Dai, Zhibin; Serna-Grey, Donald

2018-01-01

Spectra of 38 candidate or known cataclysmic variables are presented. Most are candidate dwarf novae or systems containing possible highly magnetic white dwarfs, while a few (KR Aur, LS Peg, V380 Oph, and V694 Mon) are previously known objects caught in unusual states. Individual spectra are used to confirm a dwarf nova nature or other classification while radial velocities of 15 systems provide orbital periods and velocity amplitudes that aid in determining the nature of the objects. Our results substantiate a polar nature for four objects, find an eclipsing SW Sex star below the period gap, another as a likely intermediate polar, as well as two dwarf novae with periods in the middle of the gap. Based on observations obtained with the Apache Point Observatory (APO) 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium (ARC).

Discovery of a New Classical Nova Shell Around a Nova-like Cataclysmic Variable

NASA Astrophysics Data System (ADS)

Guerrero, Martín A.; Sabin, Laurence; Tovmassian, Gagik; Santamaría, Edgar; Michel, Raul; Ramos-Larios, Gerardo; Alarie, Alexandre; Morisset, Christophe; Bermúdez Bustamante, Luis C.; González, Chantal P.; Wright, Nicholas J.

2018-04-01

The morphology and optical spectrum of IPHASX J210204.7+471015, a nebula classified as a possible planetary nebula are, however, strikingly similar to those of AT Cnc, a classical nova shell around a dwarf nova. To investigate its true nature, we have obtained high-resolution narrowband [O III] and [N II] images and deep optical spectra. The nebula shows an arc of [N II]-bright knots notably enriched in nitrogen, while an [O III]-bright bow shock is progressing throughout the ISM. Diagnostic line ratios indicate that shocks are associated with the arc and bow shock. The central star of this nebula has been identified by its photometric variability. Time-resolved photometric and spectroscopic data of this source reveal a period of 4.26 hr, which is attributed to a binary system. The optical spectrum is notably similar to that of RW Sex, a cataclysmic variable star (CV) of the UX UMa nova-like (NL) type. Based on these results, we propose that IPHASX J210204.7 + 471015 is a classical nova shell observed around a CV-NL system in quiescence.

New nova candidate in M81

NASA Astrophysics Data System (ADS)

Henze, M.; Sala, G.; Jose, J.; Figueira, J.; Hernanz, M.

2016-06-01

We report the discovery of a new nova candidate in the M81 galaxy on 16x200s stacked R filter CCD images, obtained with the 80 cm Ritchey-Chretien F/9.6 Joan Oro telescope at Observatori Astronomic del Montsec, owned by the Catalan Government and operated by the Institut d'Estudis Espacials de Catalunya, Spain, using a Finger Lakes PL4240-1-BI CCD Camera (with a Class 1 Basic Broadband coated 2k x 2k chip with 13.5 microns sq. pixels).

Swift observation of Nova Ophiuchi 2018 No.2 = PNV J17140261-2849237 = TCP J17140253-2849233

NASA Astrophysics Data System (ADS)

Sokolovsky, K.

2018-03-01

The nova candidate PNV J17140261-2849237 = TCP J17140253-2849233 was discovered by H. Nishimura, T. Kojima, K. Nishiyama and F. Kabashima. A. Takao reports the transient (9.5mag) visible at unfiltered images obtained on 2018-03-10.753 UT. Spectroscopic observations with the 2m Liverpool Telescope confirmed the transient to be a Fe II type nova (ATel #11398).

Optical and Infrared Spectral Features of Nova Canis Majoris 2018

NASA Astrophysics Data System (ADS)

Rudy, Richard; Mauerhan, Jon; Crawford, Kirk; Russell, Ray; Wiktorowicz, Sloane

2018-04-01

Optical and IR spectra from 0.47-2.5 microns (resolution: 5-30 angstroms) of Nova Canis Majoris (CBET 4499), were obtained 2018 April 21.14 (UT) with the Aerospace Corporation's 1.0 m telescope using its Visible and Infrared Imaging Spectrograph (VNIRIS).

Spectroscopic confirmation and photometry of the first reported nova in NGC 147

NASA Astrophysics Data System (ADS)

Fabrika, S.; Vinokurov, A.; Solovyeva, Yu.; Valeev, A. F.; Makarov, D. I.; Hornoch, K.; Kucakova, H.; Korotkiy, S.; Henze, M.; Shafter, A. W.

2017-12-01

We report optical spectroscopic confirmation of the recent nova TCP J00333837+4836022 in the Local Group dwarf spheroidal galaxy NGC 147. The nova was discovered 2017 Dec. 22.4056 UT by K. Itagaki (Yamagata, Japan).

X-ray Novae and Related Systems

NASA Technical Reports Server (NTRS)

Wheeler, J. Craig; Kim, Soonwook; Mineshige, Shin

1992-01-01

Accretion disk thermal instability models have been successful in accounting for the basic observations of dwarf novae and the steady behavior of nova-like systems. Models for the dwarf-nova like variability of the old nova and intermediate polar GK Per give good agreement with the burst amplitude, profile and recurrence time in the optical and UV. A month-long 'precursor plateau' in the UV is predicted for the expected 1992 outburst prior to the rise to maximum in the optical and UV. The models for the time scales of the outbursts and corresponding UV spectra at maximum are consistent with the inner edge of the accretion disk being essentially constant between quiescence and outburst and a factor of four larger than the co-rotation radius. These conclusions represent a challenge to the standard theory of magnetic accretion. Disk instability models have also given a good representation of the soft X-ray and optical outbursts of the X-ray novae A0620-00 and GS2000+25. Formation of coronae above the disk, heated by magneto-acoustic flux from the disk, may account for the temporal and spectral properties of the hard X-ray and gamma ray emission of related sources such as Cyg X-1, GS 2023+33 (V404 Cyg), IE 1740.7-2942 (the 'Galactic Center' Einstein Source), and GS 1124-683 (Nova Muscae).

Optical and X-ray rebrightening in NS X-ray Nova Aql X-1

NASA Astrophysics Data System (ADS)

Meshcheryakov, A.; Bikmaev, I.; Irtuganov, E.; Sakhibullin, N.; Vlasyuk, V. V.; Spiridonova, O. I.; Khamitov, I.; Medvedev, P.; Pavlinsky, M. N.; Tsygankov, S. S.

2017-06-01

The current outburst in NS X-ray Nova Aql X-1 has started 28 May 2017, as it was reported earlier (see ATel#10441, #10450, #10452). During optical monitoring campaign of Aql X-1, performed at 1.5-m Russian-Turkish telescope (TUBITAK National Observatory) and 1-m SAO RAS optical telescope (Special Astrophysical Observatory) we report a substantial increase of optical brightness of Aql X-1 in the last few days.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kasliwal, M. M.; Kulkarni, S. R.; Ofek, E. O.

We present photometric and spectroscopic follow-up of a sample of extragalactic novae discovered by the Palomar 60 inch telescope during a search for 'Fast Transients In Nearest Galaxies' (P60-FasTING). Designed as a fast cadence (1 day) and deep (g < 21 mag) survey, P60-FasTING was particularly sensitive to short-lived and faint optical transients. The P60-FasTING nova sample includes 10 novae in M 31, 6 in M 81, 3 in M 82, 1 in NGC 2403, and 1 in NGC 891. This significantly expands the known sample of extragalactic novae beyond the Local Group, including the first discoveries in a starburstmore » environment. Surprisingly, our photometry shows that this sample is quite inconsistent with the canonical maximum-magnitude-rate-of-decline (MMRD) relation for classical novae. Furthermore, the spectra of the P60-FasTING sample are indistinguishable from classical novae. We suggest that we have uncovered a sub-class of faint and fast classical novae in a new phase space in luminosity-timescale of optical transients. Thus, novae span two orders of magnitude in both luminosity and time. Perhaps the MMRD, which is characterized only by the white dwarf mass, was an oversimplification. Nova physics appears to be characterized by a relatively rich four-dimensional parameter space in white dwarf mass, temperature, composition, and accretion rate.« less

Discovery of a New Photometric Sub-class of Faint and Fast Classical Novae

NASA Astrophysics Data System (ADS)

Kasliwal, M. M.; Cenko, S. B.; Kulkarni, S. R.; Ofek, E. O.; Quimby, R.; Rau, A.

2011-07-01

We present photometric and spectroscopic follow-up of a sample of extragalactic novae discovered by the Palomar 60 inch telescope during a search for "Fast Transients In Nearest Galaxies" (P60-FasTING). Designed as a fast cadence (1 day) and deep (g < 21 mag) survey, P60-FasTING was particularly sensitive to short-lived and faint optical transients. The P60-FasTING nova sample includes 10 novae in M 31, 6 in M 81, 3 in M 82, 1 in NGC 2403, and 1 in NGC 891. This significantly expands the known sample of extragalactic novae beyond the Local Group, including the first discoveries in a starburst environment. Surprisingly, our photometry shows that this sample is quite inconsistent with the canonical maximum-magnitude-rate-of-decline (MMRD) relation for classical novae. Furthermore, the spectra of the P60-FasTING sample are indistinguishable from classical novae. We suggest that we have uncovered a sub-class of faint and fast classical novae in a new phase space in luminosity-timescale of optical transients. Thus, novae span two orders of magnitude in both luminosity and time. Perhaps the MMRD, which is characterized only by the white dwarf mass, was an oversimplification. Nova physics appears to be characterized by a relatively rich four-dimensional parameter space in white dwarf mass, temperature, composition, and accretion rate.

Models of classical and recurrent novae

NASA Technical Reports Server (NTRS)

Friedjung, Michael; Duerbeck, Hilmar W.

1993-01-01

The behavior of novae may be divided roughly into two separate stages: quiescence and outburst. However, at closer inspection, both stages cannot be separated. It should be attempted to explain features in both stages with a similar model. Various simple models to explain the observed light and spectral observations during post optical maximum activity are conceivable. In instantaneous ejection models, all or nearly all material is ejected in a time that is short compared with the duration of post optical maximum activity. Instantaneous ejection type 1 models are those where the ejected material is in a fairly thin shell, the thickness of which remains small. In the instantaneous ejection type 2 model ('Hubble Flow'), a thick envelope is ejected instantaneously. This envelope remains thick as different parts have different velocities. Continued ejection models emphasize the importance of winds from the nova after optical maximum. Ejection is supposed to occur from one of the components of the central binary, and one can imagine a general swelling of one of the components, so that something resembling a normal, almost stationary, stellar photosphere is observed after optical maximum. The observed characteristics of recurrent novae in general are rather different from those of classical novae, thus, models for these stars need not be the same.

Breaking the Habit: The Peculiar 2016 Eruption of the Unique Recurrent Nova M31N 2008-12a

NASA Astrophysics Data System (ADS)

Henze, M.; Darnley, M. J.; Williams, S. C.; Kato, M.; Hachisu, I.; Anupama, G. C.; Arai, A.; Boyd, D.; Burke, D.; Ciardullo, R.; Chinetti, K.; Cook, L. M.; Cook, M. J.; Erdman, P.; Gao, X.; Harris, B.; Hartmann, D. H.; Hornoch, K.; Horst, J. Chuck; Hounsell, R.; Husar, D.; Itagaki, K.; Kabashima, F.; Kafka, S.; Kaur, A.; Kiyota, S.; Kojiguchi, N.; Kučáková, H.; Kuramoto, K.; Maehara, H.; Mantero, A.; Masci, F. J.; Matsumoto, K.; Naito, H.; Ness, J.-U.; Nishiyama, K.; Oksanen, A.; Osborne, J. P.; Page, K. L.; Paunzen, E.; Pavana, M.; Pickard, R.; Prieto-Arranz, J.; Rodríguez-Gil, P.; Sala, G.; Sano, Y.; Shafter, A. W.; Sugiura, Y.; Tan, H.; Tordai, T.; Vraštil, J.; Wagner, R. M.; Watanabe, F.; Williams, B. F.; Bode, M. F.; Bruno, A.; Buchheim, B.; Crawford, T.; Goff, B.; Hernanz, M.; Igarashi, A. S.; José, J.; Motta, M.; O’Brien, T. J.; Oswalt, T.; Poyner, G.; Ribeiro, V. A. R. M.; Sabo, R.; Shara, M. M.; Shears, J.; Starkey, D.; Starrfield, S.; Woodward, C. E.

2018-04-01

Since its discovery in 2008, the Andromeda galaxy nova M31N 2008-12a has been observed in eruption every single year. This unprecedented frequency indicates an extreme object, with a massive white dwarf and a high accretion rate, which is the most promising candidate for the single-degenerate progenitor of a Type Ia supernova known to date. The previous three eruptions of M31N 2008-12a have displayed remarkably homogeneous multiwavelength properties: (i) from a faint peak, the optical light curve declined rapidly by two magnitudes in less than two days, (ii) early spectra showed initial high velocities that slowed down significantly within days and displayed clear He/N lines throughout, and (iii) the supersoft X-ray source (SSS) phase of the nova began extremely early, six days after eruption, and only lasted for about two weeks. In contrast, the peculiar 2016 eruption was clearly different. Here we report (i) the considerable delay in the 2016 eruption date, (ii) the significantly shorter SSS phase, and (iii) the brighter optical peak magnitude (with a hitherto unobserved cusp shape). Early theoretical models suggest that these three different effects can be consistently understood as caused by a lower quiescence mass accretion rate. The corresponding higher ignition mass caused a brighter peak in the free–free emission model. The less massive accretion disk experienced greater disruption, consequently delaying the re-establishment of effective accretion. Without the early refueling, the SSS phase was shortened. Observing the next few eruptions will determine whether the properties of the 2016 outburst make it a genuine outlier in the evolution of M31N 2008-12a.

Observations and simulations of nova Vul 1984 no. 2: A nova with ejecta rich in oxygen, neon, and magnesium

NASA Technical Reports Server (NTRS)

Starrfield, S.; Sonneborn, G.; Stryker, L. L.; Sparks, Warren M.; Truran, James W.; Ferland, Gary; Wagner, R. M.; Gallagher, J. S.; Wade, R.; Williams, R. E.

1988-01-01

Nova Vul 1984 no. 2 was observed with IUE from Dec. 1984 through Nov. 1987. The spectra are characterized by strong lines from Mg, Ne, C, Si, O, N, and other elements. Data obtained in the ultraviolet, infrared, and optical show that this nova is ejecting material rich in oxygen, neon, and magnesium.

Dwarf novae

NASA Technical Reports Server (NTRS)

Ladous, Constanze

1993-01-01

Dwarf novae are defined on grounds of their semi-regular brightness variations of some two to five magnitudes on time scales of typically 10 to 100 days. Historically several different classification schemes have been used. Today, dwarf novae are divided into three sub-classes: the U Geminorum stars, the SU Ursae Majoris stars, and the Z Camelopardalis stars. Outbursts of dwarf novae occur at semi-periodic intervals of time, typically every 10 to 100 days; amplitudes range from typically 2 to 5 mag. Within certain limits values are characteristic for each object. Relations between the outburst amplitude, or the total energy released during outburst, and the recurrence time have been found, as well as relations between the orbital period and the outburst decay time, the absolute magnitude during outburst maximum, and the widths of long and short outbursts, respectively. Some dwarf novae are known to have suspended their normal outburst activity altogether for a while. They later resumed it without having undergone any observable changes. The optical colors of dwarf novae all are quite similar during outburst, considerably bluer than during the quiescent state. During the outburst cycle, characteristic loops in the two color diagram are performed. At a time resolution on the order of minutes, strictly periodic photometric changes due to orbital motion become visible in the light curves of dwarf novae. These are characteristic for each system. Remarkably little is known about orbital variations during the course of an outburst. On time-scales of minutes and seconds, further more or less periodic types of variability are seen in dwarf novae. Appreciable flux is emitted by dwarf novae at all wavelengths from the X-rays to the longest IR wavelengths, and in some cases even in the radio. Most dwarf novae exhibit strong emission line spectra in the optical and UV during quiescence, although some have only very weak emissions in the optical and/or weak absorptions at UV wavelengths.

FUSE Observations of Galactic and LMC Novae in Outburst

NASA Technical Reports Server (NTRS)

Huschildt, P. H.

2001-01-01

This document is a collection of five abstracts from papers written on the 'FUSE Observations of Galactic and LMC Novae in Outburst'. The titles are the following: (1) Analyzing FUSE Observations of Galactic and LMC Novae; (2) Detailed NLTE Model Atmospheres for Novae during Outburst: Modeling Optical and Ultraviolet Observations for Nova LMC 1988; (3) Numerical Solution of the Expanding Stellar Atmosphere Problem; (4) A Non-LTE Line-Blanketed Expanding Atmosphere Model for A-supergiant Alpha Cygni; and (5) Non-LTE Model Atmosphere Analysis of the Early Ultraviolet Spectra of Nova Andromedae 1986. A list of journal publications is also included.

The supersoft X-ray source in V5116 Sagittarii. I. The high resolution spectra

NASA Astrophysics Data System (ADS)

Sala, G.; Ness, J. U.; Hernanz, M.; Greiner, J.

2017-05-01

Context. Classical nova explosions occur on the surface of an accreting white dwarf in a binary system. After ejection of a fraction of the envelope and when the expanding shell becomes optically thin to X-rays, a bright source of supersoft X-rays arises, powered by residual H burning on the surface of the white dwarf. While the general picture of the nova event is well established, the details and balance of accretion and ejection processes in classical novae are still full of unknowns. The long-term balance of accreted matter is of special interest for massive accreting white dwarfs, which may be promising supernova Ia progenitor candidates. Nova V5116 Sgr 2005b was observed as a bright and variable supersoft X-ray source by XMM-Newton in March 2007, 610 days after outburst. The light curve showed a periodicity consistent with the orbital period. During one third of the orbit the luminosity was a factor of seven brighter than during the other two thirds of the orbital period. Aims: In the present work we aim to disentangle the X-ray spectral components of V5116 Sgr and their variability. Methods: We present the high resolution spectra obtained with XMM-Newton RGS and Chandra LETGS/HRC-S in March and August 2007. Results: The grating spectrum during the periods of high-flux shows a typical hot white dwarf atmosphere dominated by absorption lines of N VI and N VII. During the low-flux periods, the spectrum is dominated by an atmosphere with the same temperature as during the high-flux period, but with several emission features superimposed. Some of the emission lines are well modeled with an optically thin plasma in collisional equilibrium, rich in C and N, which also explains some excess in the spectra of the high-flux period. No velocity shifts are observed in the absorption lines, with an upper limit set by the spectral resolution of 500 km s-1, consistent with the expectation of a non-expanding atmosphere so late in the evolution of the post-nova. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.

Boundary layers in cataclysmic variables: The HEAO-1 X-ray constraints

NASA Technical Reports Server (NTRS)

Jensen, K. A.

1983-01-01

The predictions of the boundary layer model for the X-ray emission from novae are summarized. A discrepancy between observations and theory in the X-ray observations is found. Constraints on the nature of the boundary layers in novae, based on the lack of detections of novae in the HEAO-1 soft X-ray survey are provided. Temperature and column densities for optically thick boundary layers in novae are estimated.

Radio Observations of Nova Muscae 2018 and Nova Carinae 2018 (ASASSN-18fv)

NASA Astrophysics Data System (ADS)

Ryder, S. D.; Kool, E. C.; Chomiuk, L.

2018-04-01

The two optically-bright Galactic novae in Musca (CBET #4473, ATel #11183, #11201, #11212, #11296) and in Carina (ATel #11454, #11456, #11457, #11460, #11468) were observed at radio wavelengths using the Australia Telescope Compact Array (ATCA) on 2018 Apr 3.3 UT. Nova Muscae 2018 has faded by a factor of 3 at 9.0 and 5.5 GHz since peaking at > 30 mJy/bm in mid-March.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hachisu, Izumi; Kato, Mariko, E-mail: hachisu@ea.c.u-tokyo.ac.jp, E-mail: mariko@educ.cc.keio.ac.jp

We identified a general course of classical nova outbursts in the B – V versus U – B color-color diagram. It is reported that novae show spectra similar to those of A-F supergiants near optical light maximum. However, they do not follow the supergiant sequence in the color-color diagram, neither the blackbody nor the main-sequence sequence. Instead, we found that novae evolve along a new sequence in the pre-maximum and near-maximum phases, which we call 'the nova-giant sequence'. This sequence is parallel to but Δ(U – B) ≈ –0.2 mag bluer than the supergiant sequence. This is because the massmore » of a nova envelope is much (∼10{sup –4} times) less than that of a normal supergiant. After optical maximum, its color quickly evolves back blueward along the same nova-giant sequence and reaches the point of free-free emission (B – V = –0.03, U – B = –0.97), which coincides with the intersection of the blackbody sequence and the nova-giant sequence, and remains there for a while. Then the color evolves leftward (blueward in B – V but almost constant in U – B), owing mainly to the development of strong emission lines. This is the general course of nova outbursts in the color-color diagram, which was deduced from eight well-observed novae in various speed classes. For a nova with unknown extinction, we can determine a reliable value of the color excess by matching the observed track of the target nova with this general course. This is a new and convenient method for obtaining the color excesses of classical novae. Using this method, we redetermined the color excesses of 20 well-observed novae. The obtained color excesses are in reasonable agreement with the previous results, which in turn support the idea of our general track of nova outbursts. Additionally, we estimated the absolute V magnitudes of about 30 novae using a method for time-stretching nova light curves to analyze the distance-reddening relations of the novae.« less

ASASSN-16eg: New candidate for a long-period WZ Sge-type dwarf nova

NASA Astrophysics Data System (ADS)

Wakamatsu, Yasuyuki; Isogai, Keisuke; Kimura, Mariko; Kato, Taichi; Vanmunster, Tonny; Stone, Geoff; Tordai, Tamás; Richmond, Michael; Miller, Ian; Oksanen, Arto; Itoh, Hiroshi; Akazawa, Hidehiko; Kiyota, Seiichiro; de Miguel, Enrique; Pavlenko, Elena P.; Antonyuk, Kirill A.; Antonyuk, Oksana I.; Neustroev, Vitaly V.; Sjoberg, George; Dubovsky, Pavol A.; Pickard, Roger D.; Nogami, Daisaku

2017-12-01

We report on our photometric observations of the 2016 superoutburst of ASASSN-16eg. This object showed a WZ Sge-type superoutburst with prominent early superhumps with a period of 0.075478(8) d and a post-superoutburst rebrightening. During the superoutburst plateau, it showed ordinary superhumps with a period of 0.077880(3) d and a period derivative of 10.6(1.1) × 10-5 in stage B. The orbital period (Porb), which is almost identical with the period of the early superhumps, is exceptionally long for a WZ Sge-type dwarf nova. The mass ratio (q = M2/M1) estimated from the period of developing (stage A) superhumps is 0.166(2), which is also too large for a WZ Sge-type dwarf nova. This suggests that the 2 : 1 resonance can be reached in such high-q systems, contrary to our expectation. Such conditions are considered to be achieved if the mass-transfer rate is much lower than those in typical SU UMa-type dwarf novae that have comparable orbital periods to ASASSN-16eg, and a resultant accumulation of a large amount of matter on the disk is realized at the onset of an outburst. We examined other candidates for long-period WZ Sge-type dwarf novae for their supercycles, which are considered to reflect the mass-transfer rate, and found that V1251 Cyg and RZ Leo have longer supercycles than those of other WZ Sge-type dwarf novae. This result indicates that these long-period objects including ASASSN-16eg have a low mass-transfer rate in comparison to other WZ Sge-type dwarf novae.

A deep optical imaging study of the nebular remnants of classical novae

NASA Astrophysics Data System (ADS)

Slavin, A. J.; O'Brien, T. J.; Dunlop, J. S.

1995-09-01

An optical imaging study of old nova remnants has revealed previously unobserved features in the shells of 13 classical novae - DQ Her, FH Ser, HR Del, GK Per, V1500 Cyg, T Aur, V533 Her, NQ Vul, V476 Cyg, DK Lac, LV Vul, RW UMi and V450 Cyg. These data indicate a possible correlation between nova speed class and the ellipticity of the resulting remnants - those of faster novae tend to comprise randomly distributed clumps of ejecta superposed on spherically symmetric diffuse material, whilst slower novae produce more structured ellipsoidal remnants with at least one and sometimes several rings of enhanced emission. By measuring the extent of the resolved shells and combining this information with previously published ejection speeds, we use expansion parallax to estimate distances for the 13 novae. Whilst we are able to deduce new information about every nova, it is notable that these observations include the first detections of shells around the old novae V450 Cyg and NQ Vul, and that velocity-resolved images of FH Ser and DQ Her have enabled us to estimate their orbital inclinations. Our observations of DQ Her also show that the main ellipsoidal shell is constricted by three rings and surrounded by a faint halo; this halo contains long tails extending outwards from bright knots, perhaps indicating that during or after outburst a fast inner wind has broken through the fractured principal shell.

The White Dwarf Mass and the Accretion Rate of Recurrent Novae: An X-ray Perspective

NASA Technical Reports Server (NTRS)

Mukai, Koji; Sokoloski, Jennifer L.; Nelson, Thomas; Luna, Gerardo J. M.

2011-01-01

We present recent results of quiescent X-ray observations of recurrent novae (RNe) and related objects. Several RNe are luminous hard X-ray sources in quiescence, consistent with accretion onto a near Chandrasekhar mass white dwarf. Detection of similar hard X-ray emissions in old novae and other cataclysmic variables may lead to identification of additional RN candidates. On the other hand, other RNe are found to be comparatively hard X-ray faint. We present several scenarios that may explain this dichotomy, which should be explored further.

Near-infrared and optical studies of the highly obscured nova V1831 Aquilae (Nova Aquilae 2015)

NASA Astrophysics Data System (ADS)

Banerjee, D. P. K.; Srivastava, Mudit K.; Ashok, N. M.; Munari, U.; Hambsch, F.-J.; Righetti, G. L.; Maitan, A.

2018-01-01

Near-infrared (NIR) and optical photometry and spectroscopy are presented for the nova V1831 Aquilae, covering the early decline and dust-forming phases during the first ∼90 d after its discovery. The nova is highly reddened due to interstellar extinction. Based solely on the nature of the NIR spectrum, we are able to classify the nova to be of the Fe II class. The distance and extinction to the nova are estimated to be 6.1 ± 0.5 kpc and Av ∼ 9.02, respectively. Lower limits of the electron density, emission measure and ionized ejecta mass are made from a Case B analysis of the NIR Brackett lines, while the neutral gas mass is estimated from the optical [O I] lines. We discuss the cause of the rapid strengthening of the He I 1.0830-μm line during the early stages. V1831 Aql formed a modest amount of dust fairly early (∼19.2 d after discovery); the dust shell is not seen to be optically thick. Estimates of the dust temperature, dust mass and grain size are made. Dust formation commences around day 19.2 at a condensation temperature of 1461 ± 15 K, suggestive of a carbon composition, following which the temperature is seen to decrease gradually to 950 K. The dust mass shows a rapid initial increase, which we interpret as being due to an increase in the number of grains, followed by a period of constancy, suggesting the absence of grain destruction processes during this latter time. A discussion of the evolution of these parameters is made, including certain peculiarities seen in the grain radius evolution.

The secondary maxima in black hole X-ray nova light curves - Clues toward a complete picture

NASA Technical Reports Server (NTRS)

Chen, Wan; Livio, Mario; Gehrels, Neil

1993-01-01

We study the secondary maxima observed commonly in the X-ray/optical light curves of black hole X-ray novae and show that they can play an important role in our understanding of the X-ray nova phenomenon. We discuss the observational characteristics of the secondary maxima and possible mechanisms to produce them. We propose a complete scenario for black hole X-ray nova events. The main outburst is caused by a disk instability. The second maximum is caused by X-ray evaporation of the matter near the inner Lagrangian (L1) region when the disk becomes optically thin. The third maximum (or the final minioutburst) is due to a mass transfer instability caused by hard X-ray heating of the subphotospheric layers of the secondary during the outburst. We predict that the newly discovered X-ray nova GRO J0422 + 32 may develop a final minioutburst in early 1993 and that its binary orbital period is less than 7 hr.

Strong [Fe X] Emission and Deep Optical Eclipses of the Classical Nova V5593 Sgr 2012 No. 5

NASA Astrophysics Data System (ADS)

Starrfield, Sumner; Wagner, R. Mark; Walter, Frederick M.; Woodward, Charles E.; Schwarz, Greg; Krautter, Joachim

2016-01-01

V5593 Sgr was discovered by T. Kojima on 2012 July 16.512 UT at a magnitude of ~12.6. A low-resolution spectrum obtained by M. Fujii on 2012 July 18.572 UT confirmed that the object was indeed a Classical Nova. The AAVSO V-band light curve showed that the nova peaked near 11th mag on July 23-24 UT and subsequently declined in brightness with a t_2 of about 27 days making it a moderately fast nova. We obtained optical spectroscopy of V5593 Sgr between 2012 July 26 and 2013 February 19 UT with the SMARTS/CTIO 1.5 m telescope (+RC spectrograph) and then between 2014 August 25 and 2015 June 17 UT using the MDM Observatory 2.4 m Hiltner telescope (+CCDS), the 8.4 m Large Binocular Telescope (+MODS1), and the 6.5 m MMT (+BlueChannel). The SMARTS spectra confirmed the Fe II classification but showed that by 2013 February 19 UT the Fe II lines became much weaker and strong He II 468.5 nm and [Fe VII] 608.7 nm became prominent. A spectrum obtained on 2014 August 25 UT exhibited Balmer, He II, and [Fe VII] emission lines, but also for the first time, the presence of strong [Fe X] 637.4 nm emission with an observed intensity ratio with respect to Halpha of about 1.5. Other identified emission lines in our spectra included O VI, [Ca V], [Ca VI], [Ca VII], [Fe VI], [Fe XI], and [Fe XIV]. Surprisingly, [O III] emission was weak or absent. By 2015 June, a spectrum showed that the observed [Fe X]/Halpha intensity ratio had decreased to about 0.74. Contemporaneous optical photometry was obtained with the SMARTS/CTIO 1 m telescope (+ANDICAM) between 2014 March 19 and 2015 September 28 UT in the BVRIJHK bands. In agreement with our spectra in quiescence, V5593 Sgr is very red with (B-V) ~ 1 mag and (V-K) ~ 5 mag. The photometry shows ellipsoidal-like modulations with a peak-to-peak amplitude exceeding 2 mag in R and I. The modulation is seen in B through K; however, the amplitude is lower in JHK. Brief eclipses occur at the minimum of the ellipsoidal variation with a depth of at least 5 mag in R and I. The eclipse is seen in all bands covered by our observations. Two or more candidate periods may be consistent with the data. We will discuss these results in the context of other classical novae including GQ Mus and V723 Cas.

The orbital period of the dwarf nova AF Camelopardalis

NASA Astrophysics Data System (ADS)

Szkody, Paula; Howell, Steve B.

1989-04-01

Time-resolved optical spectroscopy of the dwarf nova AF Cam for 4.5 hr during a decline from outburst reveals that the orbital period is relatively long (5-6 hr). CCD photometry at quiescence also supports this finding. This rules out the previously observed 67-76 min modulations (evident in IR photometric measurements at quiescence and optical photometry at outburst) as orbital in nature.

The Evolution of NR TrA (Nova TrA 2008) from 2008 through 2017

NASA Astrophysics Data System (ADS)

Walter, Frederick M.; Burwitz, Vadim; Kafka, Stella

2018-06-01

The classical nova NR TrA was discovered as an O-type optically-thick classical nova. There is no evidence that it formed dust. Within four years the envelope became sufficiently thin to reveal an eclipsing accretion disk-dominated system with orbitally-modulated permitted lines of C IV, N V, and O VI. XMM observations reveal a non-eclipsing soft X-ray source and a deeply-eclipsing UV continuum. We will present the first ten years of optical spectral evolution of this system accompanied by ten years of BVRIJHK photometry, with an eye to deciphering the current nature of the system.

Cataclysmic variables. Recent multi-frequency observations and theoretical developments; Proceedings of the 93rd IAU Colloquium, Bamberg, West Germany, June 16-19, 1986

NASA Technical Reports Server (NTRS)

Drechsel, H. (Editor); Rahe, J. (Editor); Kondo, Y. (Editor)

1987-01-01

Papers are presented on the formation and evolution of low-mass close binaries with compact components, the periods of cataclysmic variables, multiwavelength observations of dwarf novae during outbursts, and radio emission from cataclysmic variables. Also considered are long-term optical photometry of the dwarf nova VW Hyi, periodic modulations in the optical light curves of EX Hydrae, and Echelle-Mepsicron time-resolved spectroscopy of the dwarf nova SS Cygni. Other topics include UV and X-ray observations of cataclysmic variables, new EXOSAT observations of TV Columbae, accretion disk evolution, and the boundary layer in cataclysmic variables.

Fermi-LAT Gamma-ray Observations of Nova Lupus 2016 (ASASSN-16kt)

NASA Astrophysics Data System (ADS)

Cheung, C. C.; Jean, P.; Shore, S. N.; Fermi Large Area Telescope Collaboration

2016-10-01

The Fermi Gamma-ray Space Telescope performed a ~6-day Target of Opportunity (ToO) observation of Nova Lupus 2016 (ATel #9538, #9539, CBET #4322) that commenced on September 28. Considering earlier all-sky survey Large Area Telescope (LAT) observations as well, preliminary analysis indicates gamma-ray emission at ~2 sigma was detected around 1 to 2 days after the optical peak on September 25th (pre-validated AAVSO visual lightcurve; ATel #9550, CBET #4322) when the optical spectra show opaque ejecta, similar to previous gamma-ray detected novae (Fermi-LAT collaboration, 2014 Science 345, 554; Cheung et al. 2016 ApJ 826, 142).

Boundary layers in cataclysmic variables - The HEAO 1 X-ray constraints

NASA Technical Reports Server (NTRS)

Jensen, K. A.

1984-01-01

The predictions of the boundary layer model for the X-ray emission from novae are summarized. A discrepancy between observations and theory in the X-ray observations is found. Constraints on the nature of the boundary layers in novae, based on the lack of detections of novae in the HEAO-1 soft X-ray survey are provided. Temperature and column densities for optically thick boundary layers in novae are estimated. Previously announced in STAR as N84-13046

Novae as a Class of Transient X-ray Sources

NASA Technical Reports Server (NTRS)

Mukai, K.; Orio, M.; Valle, M. Della

2007-01-01

Motivated by the recently discovered class of faint (10(exp 34)-10(exp 35) ergs/s) X-ray transients in the Galactic Center region, we investigate the 2-10 keV properties of classical and recurrent novae. Existing data are consistent with the idea that all classical novae are transient X-ray sources with durations of months to years and peak luminosities in the 10(exp 34)-10(exp 35)ergs/s range. This makes classical novae a viable candidate class for the faint Galactic Center transients. We estimate the rate of classical novae within a 15 arcmin radius region centered on the Galactic Center (roughly the field of view of XMM-Newton observations centered on Sgr A*) to be approx.0.1 per year. Therefore, it is plausible that some of the Galactic Center transients that have been announced to date are unrecognized classical novae. The continuing monitoring of the Galactic Center region carried out by Chandra and XMM-Newton may therefore provide a new method to detect classical novae in this crowded and obscured region, an

Identifying and quantifying recurrent novae masquerading as classical novae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pagnotta, Ashley; Schaefer, Bradley E., E-mail: pagnotta@amnh.org

2014-06-20

Recurrent novae (RNe) are cataclysmic variables with two or more nova eruptions within a century. Classical novae (CNe) are similar systems with only one such eruption. Many of the so-called CNe are actually RNe for which only one eruption has been discovered. Since RNe are candidate Type Ia supernova progenitors, it is important to know whether there are enough in our Galaxy to provide the supernova rate, and therefore to know how many RNe are masquerading as CNe. To quantify this, we collected all available information on the light curves and spectra of a Galactic, time-limited sample of 237 CNemore » and the 10 known RNe, as well as exhaustive discovery efficiency records. We recognize RNe as having (1) outburst amplitude smaller than 14.5 – 4.5 × log (t {sub 3}), (2) orbital period >0.6 days, (3) infrared colors of J – H > 0.7 mag and H – K > 0.1 mag, (4) FWHM of Hα > 2000 km s{sup –1}, (5) high excitation lines, such as Fe X or He II near peak, (6) eruption light curves with a plateau, and (7) white dwarf mass greater than 1.2 M {sub ☉}. Using these criteria, we identify V1721 Aql, DE Cir, CP Cru, KT Eri, V838 Her, V2672 Oph, V4160 Sgr, V4643 Sgr, V4739 Sgr, and V477 Sct as strong RN candidates. We evaluate the RN fraction among the known CNe using three methods to get 24% ± 4%, 12% ± 3%, and 35% ± 3%. With roughly a quarter of the 394 known Galactic novae actually being RNe, there should be approximately a hundred such systems masquerading as CNe.« less

X-rays Provide a New Way to Investigate Exploding Stars

NASA Astrophysics Data System (ADS)

2007-05-01

The European Space Agency's X-ray observatory XMM-Newton has revealed a new class of exploding stars - where the X-ray emission 'lives fast and dies young'. The identification of this particular class of explosion gives astronomers a valuable new constraint to help them understand stellar explosions. Exploding stars called novae remain a puzzle to astronomers. "Modelling these outbursts is very difficult," says Wolfgang Pietsch, Max Planck Institut für Extraterrestrische Physik. Now, ESA's XMM-Newton and NASA's Chandra have provided valuable information about when individual novae emit X-rays. Between July 2004 and February 2005, the X-ray observatories watched the heart of the nearby Andromeda Galaxy, known to astronomers as M31. During that time, Pietsch and his colleagues monitored novae, looking for the X-rays. X-ray Image of Andromeda Galaxy (M31) Chandra X-ray Image of Andromeda Galaxy (M31) They detected that eleven out of the 34 novae that had exploded in the galaxy during the previous year were shining X-rays into space. "X-rays are an important window onto novae. They show the atmosphere of the white dwarf," says Pietsch. White dwarfs are hot stellar corpses left behind after the rest of the star has been ejected into space. A typical white dwarf contains about the mass of the Sun, in a spherical volume little bigger than the Earth. It has a strong pull of gravity and, if it is in orbit around a normal star, can rip gas from it. This material builds up on the surface of the white dwarf until it reaches sufficient density to nuclear detonate. The resultant explosion creates a nova. However, these particular events are not strong enough to destroy the underlying white dwarf. The X-ray emission becomes visible some time after the detonation, when the matter ejected by the nova thins out enough to allow astronomers to peer down to the nuclear burning white dwarf atmosphere beneath. At the end of the process, the X-ray emission stops when the fuel is exhausted. The duration of this X-ray emission traces the amount of material left on the white dwarf after the nova explosion. Optical Image of Andromeda Galaxy (M31) Optical Image of Andromeda Galaxy (M31) A well determined start time of the optical nova outburst and the X-ray turn-on and turn-off times are therefore important benchmarks for replication in computer models of novae. Whilst monitoring the M31 novae, frequently over several months, for the appearance and subsequent disappearance of the X-rays, Pietsch made an important discovery. Some novae start to emit X-rays and then turn them off again within just a few months. "These novae are a new class. They would have been overlooked before," says Pietsch. That's because previous surveys looked only every six months or so. Within that time, the fast X-ray novae could have blinked both on and off. In addition to discovering the short-lived ones, the new survey also confirms that other novae generate X-rays over a much longer time. XMM-Newton detected seven novae that were still shining X-rays into space, up to a decade after the original eruption. The differing lengths of times are thought to reflect the masses of the white dwarfs at the heart of the nova explosion. The fastest evolving novae are thought to be those coming from the most massive white dwarfs. To investigate further, the team have been awarded more XMM-Newton and Chandra observing time. They now plan to monitor M31's novae every ten days for several months, starting in November 2007 to glean more information about these puzzling stellar explosions. Notes for editors: X-ray monitoring of optical novae in M31 from July 2004 to February 2005 by W. Pietsch et al. is published in Astronomy and Astrophysics, 465, 375-392 (2007). For more information: Wolfgang Pietsch wnp@mpe.mpg.de Norbert Schartel Norbert.Schartel@sciops.esa.int

The Distance to Nova V959 Mon from VLA Imaging

NASA Astrophysics Data System (ADS)

Linford, J. D.; Ribeiro, V. A. R. M.; Chomiuk, L.; Nelson, T.; Sokoloski, J. L.; Rupen, M. P.; Mukai, K.; O'Brien, T. J.; Mioduszewski, A. J.; Weston, J.

2015-06-01

Determining reliable distances to classical novae is a challenging but crucial step in deriving their ejected masses and explosion energetics. Here we combine radio expansion measurements from the Karl G. Jansky Very Large Array with velocities derived from optical spectra to estimate an expansion parallax for nova V959 Mon, the first nova discovered through its γ-ray emission. We spatially resolve the nova at frequencies of 4.5-36.5 GHz in nine different imaging epochs. The first five epochs cover the expansion of the ejecta from 2012 October to 2013 January, while the final four epochs span 2014 February-May. These observations correspond to days 126 through 199 and days 615 through 703 after the first detection of the nova. The images clearly show a non-spherical ejecta geometry. Utilizing ejecta velocities derived from three-dimensional modeling of optical spectroscopy, the radio expansion implies a distance between 0.9 ± 0.2 and 2.2 ± 0.4 kpc, with a most probable distance of 1.4 ± 0.4 kpc. This distance implies a γ-ray luminosity of 0.6× {{10}35} erg s-1, which is much less than the prototype γ-ray-detected nova, V407 Cyg, possibly due to the lack of a red giant companion in the V959 Mon system. V959 Mon also has a much lower γ-ray luminosity than other classical novae detected in γ-rays to date, indicating a range of at least a factor of 10 in the γ-ray luminosities for these explosions.

The Fall and the Rise of X-Rays from Dwarf Novae in Outburst: RXTE Observations of VW Hydri and WW Ceti

NASA Technical Reports Server (NTRS)

Fertig, D.; Mukai, K.; Nelson, T.; Cannizzo, J. K.

2011-01-01

In a dwarf nova, the accretion disk around the white dwarf is a source of ultraviolet, optical, and infrared photons, but is never hot enough to emit X-rays. Observed X-rays instead originate from the boundary layer between the disk and the white dwarf. As the disk switches between quiescence and outburst states, the 2-10 keV X-ray flux is usually seen to be anti-correlated with the optical brightness. Here we present RXTE monitoring observations of two dwarf novae, VW Hyi and WW Cet, confirming the optical/X-ray anti-correlation in these two systems. However, we do not detect any episodes of increased hard X-ray flux on the rise (out of two possible chances for WW Cet) or the decline (two for WW Cet and one for VW Hyi) from outburst, attributes that are clearly established in SS Cyg. The addition of these data to the existing literature establishes the fact that the behavior of SS Cyg is the exception, rather than the archetype as is often assumed. We speculate that only dwarf novae with a massive white dwarf may show these hard X-ray spikes.

Hello darkness my old friend: the fading of the nearby TDE ASASSN-14ae

NASA Astrophysics Data System (ADS)

Brown, Jonathan S.; Shappee, Benjamin J.; Holoien, T. W.-S.; Stanek, K. Z.; Kochanek, C. S.; Prieto, J. L.

2016-11-01

We present late-time optical spectroscopy taken with the Large Binocular Telescope's Multi-Object Double Spectrograph, an improved All-Sky Automated Survey for SuperNovae pre-discovery non-detection, and late-time Swift observations of the nearby (d = 193 Mpc, z = 0.0436) tidal disruption event (TDE) ASASSN-14ae. Our observations span from ˜20 d before to ˜750 d after discovery. The proximity of ASASSN-14ae allows us to study the optical evolution of the flare and the transition to a host-dominated state with exceptionally high precision. We measure very weak Hα emission 300 d after discovery (LH α ≃ 4 × 1039 erg s-1) and the most stringent upper limit to date on the Hα luminosity ˜750 d after discovery (LH α ≲ 1039 erg s-1), suggesting that the optical emission arising from a TDE can vanish on a time-scale as short as 1 yr. Our results have important implications for both spectroscopic detection of TDE candidates at late times, as well as the nature of TDE host galaxies themselves.

Constraints on oscillation parameters from v e appearance and v μ disappearance in NOvA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adamson, P.; Aliaga, L.; Ambrose, D.

2017-06-05

Results are reported from an improved measurement of ν μ → ν e transitions by the NOvA experiment. Using an exposure equivalent to 6.05 × 10 20 protons on target, 33 νe candidates are observed with a background of 8.2 ± 0.8 (syst.). In this paper, combined with the latest NOvA νμ disappearance data and external constraints from reactor experiments on sin 22θ 13, the hypothesis of inverted mass hierarchy with θ 23 in the lower octant is disfavored at greater than 93% C.L. for all values of δ CP.

Constraints on Oscillation Parameters from νe Appearance and νμ Disappearance in NOvA

NASA Astrophysics Data System (ADS)

Adamson, P.; Aliaga, L.; Ambrose, D.; Anfimov, N.; Antoshkin, A.; Arrieta-Diaz, E.; Augsten, K.; Aurisano, A.; Backhouse, C.; Baird, M.; Bambah, B. A.; Bays, K.; Behera, B.; Bending, S.; Bernstein, R.; Bhatnagar, V.; Bhuyan, B.; Bian, J.; Blackburn, T.; Bolshakova, A.; Bromberg, C.; Brown, J.; Brunetti, G.; Buchanan, N.; Butkevich, A.; Bychkov, V.; Campbell, M.; Catano-Mur, E.; Childress, S.; Choudhary, B. C.; Chowdhury, B.; Coan, T. E.; Coelho, J. A. B.; Colo, M.; Cooper, J.; Corwin, L.; Cremonesi, L.; Cronin-Hennessy, D.; Davies, G. S.; Davies, J. P.; Derwent, P. F.; Dharmapalan, R.; Ding, P.; Djurcic, Z.; Dukes, E. C.; Duyang, H.; Edayath, S.; Ehrlich, R.; Feldman, G. J.; Frank, M. J.; Gabrielyan, M.; Gallagher, H. R.; Germani, S.; Ghosh, T.; Giri, A.; Gomes, R. A.; Goodman, M. C.; Grichine, V.; Group, R.; Grover, D.; Guo, B.; Habig, A.; Hartnell, J.; Hatcher, R.; Hatzikoutelis, A.; Heller, K.; Himmel, A.; Holin, A.; Hylen, J.; Jediny, F.; Judah, M.; Kafka, G. K.; Kalra, D.; Kasahara, S. M. S.; Kasetti, S.; Keloth, R.; Kolupaeva, L.; Kotelnikov, S.; Kourbanis, I.; Kreymer, A.; Kumar, A.; Kurbanov, S.; Lang, K.; Lee, W. M.; Lin, S.; Liu, J.; Lokajicek, M.; Lozier, J.; Luchuk, S.; Maan, K.; Magill, S.; Mann, W. A.; Marshak, M. L.; Matera, K.; Matveev, V.; Méndez, D. P.; Messier, M. D.; Meyer, H.; Miao, T.; Miller, W. H.; Mishra, S. R.; Mohanta, R.; Moren, A.; Mualem, L.; Muether, M.; Mufson, S.; Murphy, R.; Musser, J.; Nelson, J. K.; Nichol, R.; Niner, E.; Norman, A.; Nosek, T.; Oksuzian, Y.; Olshevskiy, A.; Olson, T.; Paley, J.; Pandey, P.; Patterson, R. B.; Pawloski, G.; Pershey, D.; Petrova, O.; Petti, R.; Phan-Budd, S.; Plunkett, R. K.; Poling, R.; Potukuchi, B.; Principato, C.; Psihas, F.; Radovic, A.; Rameika, R. A.; Rebel, B.; Reed, B.; Rocco, D.; Rojas, P.; Ryabov, V.; Sachdev, K.; Sail, P.; Samoylov, O.; Sanchez, M. C.; Schroeter, R.; Sepulveda-Quiroz, J.; Shanahan, P.; Sheshukov, A.; Singh, J.; Singh, J.; Singh, P.; Singh, V.; Smolik, J.; Solomey, N.; Song, E.; Sousa, A.; Soustruznik, K.; Strait, M.; Suter, L.; Talaga, R. L.; Tamsett, M. C.; Tas, P.; Thayyullathil, R. B.; Thomas, J.; Tian, X.; Tognini, S. C.; Tripathi, J.; Tsaris, A.; Urheim, J.; Vahle, P.; Vasel, J.; Vinton, L.; Vold, A.; Vrba, T.; Wang, B.; Wetstein, M.; Whittington, D.; Wojcicki, S. G.; Wolcott, J.; Yadav, N.; Yang, S.; Zalesak, J.; Zamorano, B.; Zwaska, R.; NOvA Collaboration

2017-06-01

Results are reported from an improved measurement of νμ→νe transitions by the NOvA experiment. Using an exposure equivalent to 6.05 ×1 020 protons on target, 33 νe candidates are observed with a background of 8.2 ±0.8 (syst.). Combined with the latest NOvA νμ disappearance data and external constraints from reactor experiments on sin22 θ13, the hypothesis of inverted mass hierarchy with θ23 in the lower octant is disfavored at greater than 93% C.L. for all values of δC P.

The Stony Brook/SMARTS Atlas of (mostly) Southern Novae

NASA Astrophysics Data System (ADS)

Walter, F. M.

2014-12-01

The Stony Brook/SMARTS Atlas of (mostly) Southern Novae is an on-line compendium of data on 69 novae, mostly in the southern hemisphere, observed since 2003 April. The data consist of low resolution spectra (400< R <4000) and optical and near-IR photometry obtained with the SMARTS telescopes. I shall describe the atlas and the data, and then present some examples of the data analyzes being undertaken with this synoptic data set.

MULTIPLICITY OF NOVA ENVELOPE SOLUTIONS AND OCCURRENCE OF OPTICALLY THICK WINDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kato, Mariko; Hachisu, Izumi

2009-07-10

We revisit the occurrence condition of optically thick winds reported by Kato in 1985 and Kato and Hachisu in 1989 who mathematically examined nova envelope solutions with an old opacity and found that optically thick winds are accelerated only in massive white dwarfs (WDs) of {approx}>0.9 M{sub sun}. With the OPAL opacity we find that the optically thick wind occurs for {approx}>0.6 M{sub sun} WDs and that the occurrence of winds depends not only on the WD mass but also on the ignition mass. When the ignition mass is larger than a critical value, winds are suppressed by a density-inversionmore » layer. Such a static solution can be realized in WDs of mass {approx}0.6-0.7 M{sub sun}. We propose that sequences consisting only of static solutions correspond to slow evolutions in symbiotic novae like PU Vul because PU Vul shows no indication of strong winds in a long-lasted flat peak followed by a very slow decline in its light curve.« less

Fermi-LAT Bright Gamma-ray Detection of Nova ASASSN-18fv

NASA Astrophysics Data System (ADS)

Jean, P.; Cheung, C. C.; Ojha, R.; van Zyl, P.; Angioni, R.

2018-04-01

The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed bright gamma-ray emission from a source positionally consistent with the bright optical nova ASASSN-18fv (ATel #11454, #11456, #11460, #11467, #11508).

Optical and Infrared Spectroscopy of Nova Ophiuchi 2018 No.2

NASA Astrophysics Data System (ADS)

Rudy, R. J.; Mauerhan, J. C.; Russell, R. W.; Subasavage, J. P.; Wiktorowicz, S. J.; Kim, D. L.; Sitko, M. L.

2018-05-01

Over a two week period coming approximately two months after outburst, Nova Ophiuchi 2018, No.2 (CBET 4492) was observed spectroscopically using instruments from three different facilities: 2018 May 6, using the Spex instrument at the Infrared Telescope Facility (0.7-2.5 microns); 2018 May 14, using the Broadband Array Spectrograph System on the 3.6 meter Advanced Electro-Optical Systems telescope (3-13 microns); 2018 May 19, with the VNIRIS spectrograph on the Aerospace Corporation's one meter telescope (0.47-2.5 microns).

The active quiescence of HR Del (Nova Del 1967). The ex-nova HR Del

NASA Astrophysics Data System (ADS)

Selvelli, P.; Friedjung, M.

2003-04-01

This new UV study of the ex-nova HR Del is based on all of the data obtained with the International Ultraviolet Explorer (IUE) satellite, and includes the important series of spectra taken in 1988 and 1992 that have not been analyzed so far. This has allowed us to make a detailed study of both the long-timescale and the short-timescale UV variations, after the return of the nova, around 1981-1982, to the pre-outburst optical magnitude. After the correction for the reddening (EB-V=0.16), adopting a distance d =850 pc we have derived a mean UV luminosity close to LUV ~ 56 Lsun, the highest value among classical novae in ``quiescence". Also the ``average" optical absolute magnitude (Mv=+2.30) is indicative of a bright object. The UV continuum luminosity, the HeII 1640 Å emission line luminosity, and the optical absolute magnitude all give a mass accretion rate dot {M} very close to 1.4x 10-7 Msun yr-1, if one assumes that the luminosity of the old nova is due to a non-irradiated accretion disk. The UV continuum has declined by a factor less than 1.2 over the 13 years of the IUE observations, while the UV emission lines have faded by larger factors. The continuum distribution is well fitted with either a black body of 33 900 K, or a power-law Flambda ~ lambda -2.20. A comparison with the grid of models of Wade & Hubeny (\\cite{Wade}) indicates a low M1 value and a relatively high dot {M} but the best fittings to the continuum and the line spectrum come from different models. We show that the ``quiescent" optical magnitude at mv ~ 12 comes from the hot component and not from the companion star. Since most IUE observations correspond to the ``quiescent" magnitude at mv ~ 12, the same as in the pre-eruption stage, we infer that the pre-nova, for at least 70 years prior to eruption, was also very bright at near the same LUV, Mv, dot {M}, and T values as derived in the present study for the ex-nova. The wind components in the P Cyg profiles of the CIV 1550 Å and NV 1240 Å resonance lines are strong and variable on short timescales, with vedge up to -5000 km s-1, a remarkably high value. The phenomenology of the short-time variations of the wind indicates the presence of an inhomogeneous outflow. We discuss the nature of the strong UV continuum and wind features and the implications of the presence of a ``bright" state a long time before and after outburst on our present knowledge of the pre-nova and post-nova behavior. Based on observations made with the International Ultraviolet Explorer and de-archived from the ESA VILSPA Database. }

The optical re-brightening of nova M31N 2017-11a

NASA Astrophysics Data System (ADS)

Xu, Zhijian; Gao, Xing; Li, Yanxi; Zhao, Jingyuan; Zhang, Mi

2017-12-01

We report the initial discovery of the optical re-brightening of the Fe II class nova M31N 2017-11a (AT2017hvi = PTSS-17zap) which was first reported by PMO-Tsinghua Supernova Survey (PTSS, http://www.cneost.org/ptss/ ), (2017, TNS Discovery Report https://wis-tns.weizmann.ac.il/object/2017hvi) at r-Sloan magnitude 18.5 on 2017-11-04 16:41:02 UT. Spectroscopy by Williams & Darnley using the 2-m Liverpool telescope (ATel #10990) on 2017 Nov 20.11 UT, and by Fabrika et al., (ATel #10998) taken two days later at the Russian BTA telescope, showed Balmer emission lines together with numerous strong Fe II lines, confirming its classification as a classical Fe II class nova.

Ultraviolet spectroscopy of old novae and symbiotic stars

NASA Technical Reports Server (NTRS)

Lambert, D. L.; Slovak, M. H.; Shields, G. A.; Ferland, G. J.

1981-01-01

The IUE spectra are presented for two old novae and for two of the symbiotic variables. Prominent emission line spectra are revealed as a continuum whose appearance is effected by the system inclination. These data provide evidence for hot companions in the symbiotic stars, making plausible the binary model for these peculiar stars. Recent IUE spectra of dwarf novae provide additional support for the existence of optically thick accretion disks in active binary systems. The ultraviolet data of the eclipsing dwarf novae EX Hya and BV Cen appear flatter than for the noneclipsing systems, an effect which could be ascribed to the system inclination.

β Decay as a Probe of Explosive Nucleosynthesis in Classical Novae

NASA Astrophysics Data System (ADS)

Wrede, C.; Bennett, M. B.; Liddick, S. N.; Bardayan, D. W.; Bowe, A.; Brown, B. A.; Chen, A. A.; Chipps, K. A.; Cooper, N.; Fry, C.; Glassman, B.; Irvine, D.; José, J.; Langer, C.; Larson, N.; McNeice, E. I.; Meisel, Z.; Montes, F.; Naqvi, F.; Pain, S. D.; O'Malley, P.; Ortez, R.; Ong, W.; Pereira, J.; Pérez-Loureiro, D.; Prokop, C.; Quaglia, J.; Quinn, S.; Santia, M.; Schatz, H.; Schwartz, S. B.; Simon, A.; Shanab, S.; Spyrou, A.; Suchyta, S.; Thiagalingam, E.; Thompson, P.; Walters, M.

Classical novae are common thermonuclear explosions in the Milky Way galaxy, occurring on the surfaces of white-dwarf stars that are accreting hydrogen-rich material from companion stars. Nucleosynthesis in classical novae depends on radiative proton-capture reaction rates on radioactive nuclides. Many of these reactions cannot be measured directly at current accelerator facilities due to the lack of intense, high-quality, radioactive-ion beams at the relevant energies. Since most of these reactions proceed via resonant capture, their rates can be determined indirectly by measuring the properties of the resonances. At the National Superconducting Cyclotron Laboratory, we have used the β-delayed γ decays of 26P and 31Cl to populate resonances in 26Si and 31S and study the radiative proton captures on 25Al and 30P, respectively. These were two out of the three most important nuclear-physics uncertainties associated with the observable products of nova nucleosynthesis. The 26P experiment has enabled a more accurate estimate of the nova contribution to the long-lived Galactic 26Al detected with γ-ray telescopes. The 31Cl experiment, currently under analysis, will calibrate potential nova thermometers and mixing meters based on elemental abundance ratios, and facilitate the identification of pre-solar nova grain candidates found in primitive meteorites based on isotopic ratios.

Optical Spectroscopy of Nova Ophiuchi 2015 (PNV J17291350-1846120)

NASA Astrophysics Data System (ADS)

Danilet, A. B.; Holoien, T. W.-S.; Wagner, R. M.; Woodward, C. E.; Starrfield, S.; Wilber, A.; Walter, F.; Shore, S.

2015-04-01

Following the discovery by Y. Sakurai (Ibaraki-ken, Japan) on 2015 Mar. 29.766 UT of a new stellar object of magnitude 12.2 in Ophiuchus (S. Nakano, CBET 4086) and its subsequent confirmation as a likely He/N classical nova (K Ayani, CBET 4086), we obtained a spectrum (range: 398-685 nm; resolution 0.3 nm) of Nova Oph 2015 on 2015 April 1.459 UT with the 2.4 m Hiltner telescope (+OSMOS) of the MDM Observatory on Kitt Peak.

INFRARED SPECTROSCOPY OF SYMBIOTIC STARS. IX. D-TYPE SYMBIOTIC NOVAE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinkle, Kenneth H.; Joyce, Richard R.; Fekel, Francis C.

2013-06-10

Time-series spectra of the near-infrared 1.6 {mu}m region have been obtained for five of the six known D-type symbiotic novae. The spectra map the pulsation kinematics of the Mira component in the Mira-white dwarf binary system and provide the center-of-mass velocity for the Mira. No orbital motion is detected in agreement with previous estimates of orbital periods {approx}>100 yr and semimajor axes {approx}50 AU. The 1-5 {mu}m spectra of the Miras show line weakening during dust obscuration events. This results from scattering and continuum emission by 1000 K dust. In the heavily obscured HM Sge system the 4.6 {mu}m COmore » spectrum formed in 1000 K gas is seen in emission against an optically thick dust continuum. Spectral features that are typically produced in either the cool molecular region or the expanding circumstellar region of late-type stars cannot be detected in the D-symbiotic novae. This is in accord with the colliding wind model for interaction between the white dwarf and Mira. Arguments are presented that the 1000 K gas and dust are not Mira circumstellar material but are in the wind interaction region of the colliding winds. CO is the first molecule detected in this region. We suggest that dust condensing in the intershock region is the origin of the dust obscuration. This model explains variations in the obscuration. Toward the highly obscured Mira in HM Sge the dust zone is estimated to be {approx}0.1 AU thick. The intershock wind interaction zone appears thinnest in the most active systems. Drawing on multiple arguments masses are estimated for the system components. The Miras in most D-symbiotic novae have descended from intermediate mass progenitors. The large amount of mass lost from the Mira combined with the massive white dwarf companion suggests that these systems are supernova candidates. However, timescales and the number of objects make these rare events.« less

Polarimetry and spectroscopy of the "oxygen flaring" DQ Herculis-like nova: V5668 Sagittarii (2015)

NASA Astrophysics Data System (ADS)

Harvey, E. J.; Redman, M. P.; Darnley, M. J.; Williams, S. C.; Berdyugin, A.; Piirola, V. E.; Fitzgerald, K. P.; O'Connor, E. G. P.

2018-03-01

Context. Classical novae are eruptions on the surface of a white dwarf in a binary system. The material ejected from the white dwarf surface generally forms an axisymmetric shell of gas and dust around the system. The three-dimensional structure of these shells is difficult to untangle when viewed on the plane of the sky. In this work a geometrical model is developed to explain new observations of the 2015 nova V5668 Sagittarii. Aim. We aim to better understand the early evolution of classical nova shells in the context of the relationship between polarisation, photometry, and spectroscopy in the optical regime. To understand the ionisation structure in terms of the nova shell morphology and estimate the emission distribution directly following the light curve's dust-dip. Methods: High-cadence optical polarimetry and spectroscopy observations of a nova are presented. The ejecta is modelled in terms of morpho-kinematics and photoionisation structure. Results: Initially observational results are presented, including broadband polarimetry and spectroscopy of V5668 Sgr nova during eruption. Variability over these observations provides clues towards the evolving structure of the nova shell. The position angle of the shell is derived from polarimetry, which is attributed to scattering from small dust grains. Shocks in the nova outflow are suggested in the photometry and the effect of these on the nova shell are illustrated with various physical diagnostics. Changes in density and temperature as the super soft source phase of the nova began are discussed. Gas densities are found to be of the order of 109 cm-3 for the nova in its auroral phase. The blackbody temperature of the central stellar system is estimated to be around 2.2 × 105 K at times coincident with the super soft source turn-on. It was found that the blend around 4640 Å commonly called "nitrogen flaring" is more naturally explained as flaring of the O II multiplet (V1) from 4638-4696 Å, i.e. "oxygen flaring". Conclusions: V5668 Sgr (2015) was a remarkable nova of the DQ Her class. Changes in absolute polarimetric and spectroscopic multi-epoch observations lead to interpretations of physical characteristics of the nova's evolving outflow. The high densities that were found early-on combined with knowledge of the system's behaviour at other wavelengths and polarimetric measurements strongly suggest that the visual "cusps" are due to radiative shocks between fast and slow ejecta that destroy and create dust seed nuclei cyclically.

Binary Orbits as the Driver of Gamma-Ray Emission and Mass Ejection in Classical Novae

NASA Technical Reports Server (NTRS)

Chomiuk, Laura; Linford, Justin D.; Yang, Jun; O'Brien, T. J.; Paragi, Zsolt; Mioduszewski, Amy J.; Beswick, R. J.; Cheung, C. C.; Mukai, Koji; Nelson, Thomas

2014-01-01

Classical novae are the most common astrophysical thermonuclear explosions, occurring on the surfaces of white dwarf stars accreting gas from companions in binary star systems. Novae typically expel about 10 (sup -4) solar masses of material at velocities exceeding 1,000 kilometers per second.However, the mechanism of mass ejection in novae is poorly understood, and could be dominated by the impulsive flash of thermonuclear energy, prolonged optically thick winds or binary interaction with the nova envelope. Classical novae are now routinely detected at giga-electronvolt gamma-ray wavelengths, suggesting that relativistic particles are accelerated by strong shocks in the ejecta. Here we report high-resolution radio imaging of the gamma-ray-emitting nova V959 Mon. We find that its ejecta were shaped by the motion of the binary system: some gas was expelled rapidly along the poles as a wind from the white dwarf, while denser material drifted out along the equatorial plane, propelled by orbital motion..At the interface between the equatorial and polar regions, we observe synchrotron emission indicative of shocks and relativistic particle acceleration, thereby pinpointing the location of gamma-ray production. Binary shaping of the nova ejecta and associated internal shocks are expected to be widespread among novae, explaining why many novae are gamma-ray emitters.

The HEAO-A2 soft X-ray survey of cataclysmic variable stars - EX Hydrae during optical quiescence

NASA Technical Reports Server (NTRS)

Cordova, F. A.; Riegler, G. R.

1979-01-01

Results are reported for HEAO A2 soft X-ray (below 2 keV) scanning observations of the southern dwarf nova EX Hya. An X-ray light curve is presented which shows no apparent orbital modulation. The best-fitting spectral parameters are derived for the source, and the observations are compared with the spectral behavior of the dwarf nova SS Cyg during optical quiescence. The results are discussed in terms of models for X-ray production by accreting white dwarfs.

Optical Spectroscopy of TCP J04432130+4721280 (V392 Per) Confirms a Nova Eruption

NASA Astrophysics Data System (ADS)

Wagner, R. M.; Terndrup, D.; Darnley, M. J.; Starrfield, S.; Woodward, C. E.; Henze, M.

2018-04-01

Following reports of a new transient of magnitude 6.2 in Perseus on 2018 April 29.4740 UT discovered by Y. Nakamura designated TCP J04432130+4721280 (http://www.cbat.eps.harvard.edu/unconf/followups/J04432130+4721280.html) and positionally coincident with the previously known U Gem type dwarf nova V392 Per, we obtained an optical spectrum on 2018 April 30.116 UT (range: 396-687 nm; resolution 0.3 nm) with the 2.4 m Hiltner telescope (+OSMOS) of the MDM Observatory on Kitt Peak.

Multiwavelength Modeling of Nove Atmospheres

NASA Technical Reports Server (NTRS)

Huschildt, P. H.

2001-01-01

LMC 1988 #1 was a slow, CO type, dust forming classical nova. It was the first extragalactic nova to be observed with the IUE satellite. We have successfully fitted observed ultraviolet and optical spectra of LMC 1988 #1 taken within the first two months of its outburst (when the atmosphere was still optically thick) with synthetic spectra computed using PHOENIX nova model atmospheres. The synthetic spectra reproduce most of the features seen in the spectra and provide V band magnitudes consistent with the observed light curve. The fits are improved by increasing the CNO abundances to 10 times the solar values. The bolometric luminosity of LMC 1988 #1 was approximately constant at 2 x 10(exp 38) ergs per second at a distance of 47.3 kpc for the first 2 months of the outburst until the formation of the dust shell.

The inter-outburst behavior of cataclysmic variables

NASA Technical Reports Server (NTRS)

Szkody, Paula; Mattei, Janet A.; Waagen, Elizabeth O.; Stablein, Clay

1990-01-01

Existing International Ultraviolet Explorer (IUE) and American Association of Variable Star Observers (AAVSO) archive data was used to accomplish a large scale study of what happens to the ultraviolet flux of accretion disk systems during the quiescent intervals between outbursts and how it relates to the preceding outburst characteristics of amplitude and width. The data sample involved multiple IUE observations for 16 dwarf novae and 8 novae along with existing optical coverage. Results indicate that most systems show correlated ultraviolet (UV) flux behavior with interoutburst phase, with 60 percent of the dwarf novae and 50 percent of the novae having decreasing flux trends while 33 percent of the dwarf novae and 38 percent of the novae show rising UV flux during the quiescent interval. All of the dwarf novae with decreasing UV fluxes at 1475A have orbital periods longer than 4.4 hours, while all (except BV Cen) with flat or rising fluxes at 1475A have orbital periods less than two hours. There are not widespread correlations of the UV fluxes with the amplitude of the preceding outburst and no correlations with the width of the outburst. From a small sample (7) that have relatively large quiescent V magnitude changes between the IUE observations, most show a strong correlation between the UV and optical continuum. Interpretation of the results is complicated by not being able to determine how much the white dwarf contributes to the ultraviolet flux. However, it is now evident that noticeable changes are occurring in the hot zones in accreting systems long after the outburst, and not only for systems that are dominated by the white dwarf. Whether these differences are due to different outburst mechanisms or to changes on white dwarfs which provide varying contributions to the UV flux remains to be determined.

SCAT Classification of 4 Optical Transients

NASA Astrophysics Data System (ADS)

Tucker, Michael A.; Rowan, Dominick M.; Shappee, Benjamin J.; Dong, Subo; Bose, Subhash; Stanek, K. Z.

2018-06-01

The Spectral Classification of Astronomical Transients (SCAT) survey (ATel #11444) presents the classification of 4 optical transients. We report optical spectroscopy (330-970nm) taken with the University of Hawaii 88-inch (UH88) telescope using the SuperNova Integral Field Spectrograph (SNIFS).

Gamma-ray emission concurrent with the nova in the symbiotic binary V407 Cygni.

PubMed

Abdo, A A; Ackermann, M; Ajello, M; Atwood, W B; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bouvier, A; Brandt, T J; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Buehler, R; Burnett, T H; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Carrigan, S; Casandjian, J M; Cecchi, C; Celik, O; Charles, E; Chaty, S; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Corbel, S; Corbet, R; DeCesar, M E; den Hartog, P R; Dermer, C D; de Palma, F; Digel, S W; Donato, D; do Couto e Silva, E; Drell, P S; Dubois, R; Dubus, G; Dumora, D; Favuzzi, C; Fegan, S J; Ferrara, E C; Fortin, P; Frailis, M; Fuhrmann, L; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grondin, M-H; Grove, J E; Guiriec, S; Hadasch, D; Harding, A K; Hayashida, M; Hays, E; Healey, S E; Hill, A B; Horan, D; Hughes, R E; Itoh, R; Jean, P; Jóhannesson, G; Johnson, A S; Johnson, R P; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kerr, M; Knödlseder, J; Koerding, E; Kuss, M; Lande, J; Latronico, L; Lee, S-H; Lemoine-Goumard, M; Garde, M Llena; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Makeev, A; Mazziotta, M N; McConville, W; McEnery, J E; Mehault, J; Michelson, P F; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Naumann-Godo, M; Nestoras, I; Nolan, P L; Norris, J P; Nuss, E; Ohno, M; Ohsugi, T; Okumura, A; Omodei, N; Orlando, E; Ormes, J F; Ozaki, M; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Ray, P S; Razzano, M; Razzaque, S; Rea, N; Reimer, A; Reimer, O; Reposeur, T; Ripken, J; Ritz, S; Romani, R W; Roth, M; Sadrozinski, H F-W; Sander, A; Parkinson, P M Saz; Scargle, J D; Schinzel, F K; Sgrò, C; Shaw, M S; Siskind, E J; Smith, D A; Smith, P D; Sokolovsky, K V; Spandre, G; Spinelli, P; Stawarz, Ł; Strickman, M S; Suson, D J; Takahashi, H; Takahashi, T; Tanaka, T; Tanaka, Y; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Uchiyama, Y; Usher, T L; Vandenbroucke, J; Vasileiou, V; Vilchez, N; Vitale, V; Waite, A P; Wallace, E; Wang, P; Winer, B L; Wolff, M T; Wood, K S; Yang, Z; Ylinen, T; Ziegler, M; Maehara, H; Nishiyama, K; Kabashima, F; Bach, U; Bower, G C; Falcone, A; Forster, J R; Henden, A; Kawabata, K S; Koubsky, P; Mukai, K; Nelson, T; Oates, S R; Sakimoto, K; Sasada, M; Shenavrin, V I; Shore, S N; Skinner, G K; Sokoloski, J; Stroh, M; Tatarnikov, A M; Uemura, M; Wahlgren, G M; Yamanaka, M

2010-08-13

Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here, we report the Fermi Large Area Telescope detection of variable gamma-ray emission (0.1 to 10 billion electron volts) from the recently detected optical nova of the symbiotic star V407 Cygni. We propose that the material of the nova shell interacts with the dense ambient medium of the red giant primary and that particles can be accelerated effectively to produce pi(0) decay gamma-rays from proton-proton interactions. Emission involving inverse Compton scattering of the red giant radiation is also considered and is not ruled out.

MAXI/GSC detection of a new outburst from the black hole candidate H 1743-322

NASA Astrophysics Data System (ADS)

Shidatsu, M.; Nakahira, S.; Negoro, H.; Ueno, S.; Tomida, H.; Ishikawa, M.; Sugawara, Y.; Nakagawa, Y. E.; Mihara, T.; Sugizaki, M.; Serino, M.; Iwakiri, W.; Sugimoto, J.; Takagi, T.; Matsuoka, M.; Kawai, N.; Isobe, N.; Sugita, S.; Yoshii, T.; Tachibana, Y.; Ono, Y.; Fujiwara, T.; Harita, S.; Muraki, Y.; Yoshida, A.; Sakamoto, T.; Kawakubo, Y.; Kitaoka, Y.; Tsunemi, H.; Shomura, R.; Nakajima, M.; Tanaka, K.; Masumitsu, T.; Kawase, T.; Ueda, Y.; Kawamuro, T.; Hori, T.; Tanimoto, A.; Oda, S.; Tsuboi, Y.; Nakamura, Y.; Sasaki, R.; Yamauchi, M.; Furuya, K.; Yamaoka, K.

2016-11-01

The MAXI/GSC nova-alert system detected an X-ray brightening of the Galactic black hole candidate H 1743-322 in November 6, UT 03:01. The 2-20 keV flux increased from 12 +- 3 mCrab on November 4 (MJD 57696) to 37 +- 5 mCrab on November 6 (MJD 57698).

MULTIWAVELENGTH PHOTOMETRY AND HUBBLE SPACE TELESCOPE SPECTROSCOPY OF THE OLD NOVA V842 CENTAURUS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sion, Edward M.; Szkody, Paula; Mukadam, Anjum

2013-08-01

We present ground-based optical and near infrared photometric observations and Hubble Space Telescope (HST) COS spectroscopic observations of the old nova V842 Cen (Nova Cen 1986). Analysis of the optical light curves reveals a peak at 56.5 {+-} 0.3 s with an amplitude of 8.9 {+-} 4.2 mma, which is consistent with the rotation of a magnetic white dwarf primary in V842 Cen that was detected earlier by Woudt et al., and led to its classification as an intermediate polar. However, our UV lightcurve created from the COS time-tag spectra does not show this periodicity. Our synthetic spectral analysis ofmore » an HST COS spectrum rules out a hot white dwarf photosphere as the source of the FUV flux. The best-fitting model to the COS spectrum is a full optically thick accretion disk with no magnetic truncation, a low disk inclination angle, low accretion rate and a distance less than half the published distance that was determined on the basis of interstellar sodium D line strengths. Truncated accretion disks with truncation radii of 3 R{sub wd} and 5 R{sub wd} yielded unsatisfactory agreement with the COS data. The accretion rate is unexpectedly low for a classical nova only 24 yr after the explosion when the accretion rate is expected to be high and the white dwarf should still be very hot, especially if irradiation of the donor star took place. Our low accretion rate is consistent with those derived from X-ray and ground-based optical data.« less

NovaSearch Online: Research Experience in Astronomy 101

NASA Astrophysics Data System (ADS)

Pilachowski, C. A.; Rector, T.; Morris, F.; Tebbe, H.

2003-12-01

A new website at the University of Indiana Bloomington allows undergraduate, introductory astronomy students to participate in original research, discovering novae in the Andromeda Galaxy. Sequences of CCD images obtained with the WIYN 0.9-m telescope at Kitt Peak of the central region of Andromeda are displayed on the Web as Flash movies, allowing students to identify novae as new, blinking stars. Tools are provided to estimate the magnitude of the novae and to determine the Julian date of observations, so that students can plot light curves. The goal of NovaSearch is to engage students in the process of discovery, applying the content they learn from textbooks and lectures to real observations and the creation of new knowledge. NovaSearch is supplemented with live video interactions with on-site observers and remote observing at the 0.9-m telescope. For many students, NovaSearch is their first experience with science as a creative, human activity. NovaSearch is available for examination and use at www.astro.indiana.edu/novasearch/ Support from the SBC Fellows program at Indiana University, as well as from the National Science Foundation through grant ESI 0101982 to the National Optical Astronomy Observatory, is gratefully acknowledged.

William Molyneux and the optometry content of his 1692 book Dioptrica Nova.

PubMed

Goss, David A

2008-04-01

This paper provides an overview of the life of William Molyneux (1656-1698) and his book Dioptrica Nova, published in 1692. The first part of that book examines the geometrical optics of lenses, the eye, telescopes, and microscopes. The second part consists of commentaries on various topics, including spectacles, telescopes, and physiological diplopia.

V1369 Cen High-resolution Panchromatic Late Nebular Spectra in the Context of a Unified Picture for Nova Ejecta

NASA Astrophysics Data System (ADS)

Mason, Elena; Shore, Steven N.; De Gennaro Aquino, Ivan; Izzo, Luca; Page, Kim; Schwarz, Greg J.

2018-01-01

Nova Cen 2013 (V1369 Cen) is the fourth bright nova observed panchromatically through high-resolution UV+optical multiepoch spectroscopy. It is also the nova with the richest set of spectra (in terms of both data quality and number of epochs) thanks to its exceptional brightness. Here, we use the late nebular spectra taken between day ∼250 and day ∼837 after outburst to derive the physical, geometrical, and kinematical properties of the nova. We compare the results with those determined for the other panchromatic studies in this series: T Pyx, V339 Del (nova Del 2013), and V959 Mon (nova Mon 2012). From this we conclude that in all these novae the ejecta geometry and phenomenology can be consistently explained by clumpy gas expelled during a single, brief ejection episode and in ballistic expansion, and not by a wind. For V1369 Cen the ejecta mass (∼1 × 10‑4 M⊙) and filling factor (0.1 ≤ f ≤ 0.2) are consistent with those of classical novae but larger (by at least an order of magnitude) than those of T Pyx and the recurrent novae. V1369 Cen has an anomalously high (relative to solar) N/C ratio that is beyond the range currently predicted for a CO nova, and the Ne emission line strengths are dissimilar to those of typical ONe or CO white dwarfs.

Manufacturing, integration, and test results of the MATISSE cold optics bench

NASA Astrophysics Data System (ADS)

Bettonvil, Felix C. M.; Kroes, G.; Agoćs, T.; van Duin, A.; Elswijk, E.; de Haan, M.; ter Horst, R.; Kragt, J.; Kuindersma, J.; Navarro, R.; Roelfsema, R.; Schuil, M.; Tromp, T.; Venema, L.; van Kessel, F.; Jaskó, A.

2014-07-01

MATISSE is the second-generation mid-infrared interferometric spectrograph and imager for ESO's Very Large Telescope Interferometer (VLTI). NOVA-ASTRON is responsible for the Cold Optics Bench (COB), representing the last part of the optics train where the four beams are re-arranged, spectrally dispersed and combined. The COB consist of two sister units, one for the LM-band, one for the N-band, which were successively completed at NOVA-ASTRON in autumn 2013 and spring 2014. The LM-band COB is under cryogenic test in its cryostat at MPIA/Heidelberg; the N-band COB finished cryogenic tests and has been installed at OCA/Nice for integration together with the Warm Optics. This paper focuses on the manufacturing, integration and test results of the COBs, and gives an overview of the current status.

An extensive optical study of V2491 Cyg (Nova Cyg 2008 N.2), from maximum brightness to return to quiescence

NASA Astrophysics Data System (ADS)

Munari, U.; Siviero, A.; Dallaporta, S.; Cherini, G.; Valisa, P.; Tomasella, L.

2011-04-01

The photometric and spectroscopic evolution of the He/N and very fast Nova Cyg 2008 N.2 (V2491 Cyg) is studied in detail. A primary maximum was reached at V = 7.45 ± 0.05 on April 11.37 (±0.1) 2008 UT, followed by a smooth decline characterized by t2V=4.8 days, and then a second maximum was attained at V = 9.49 ± 0.03, 14.5 days after the primary one. This is the only third nova to have displayed a secondary maximum, after V2362 Cyg and V1493 Aql. The development and energetics of the secondary maximum is studied in detail. The smooth decline that followed was accurately monitored until day +144 when the nova was 8.6 mag fainter than maximum brightness, well into its nebular phase, with its line and continuum emissivity declining as t-3. The reddening affecting the nova was EB- V = 0.23 ± 0.01, and the distance of 14 kpc places the nova at a height above the galactic plane of 1.1 kpc, larger than typical for He/N novae. The expansion velocity of the bulk of ejecta was 2000 km/s, with complex emission profiles and weak P-Cyg absorptions during the optically thick phase, and saddle-like profiles during the nebular phase. Photo-ionization analysis of the emission line spectrum indicates that the mass ejected by the outburst was 5.3 × 10 -6 M ⊙ and the mass fractions to be X = 0.573, Y = 0.287, Z = 0.140, with those of individual elements being N = 0.074, O = 0.049, Ne = 0.015. The metallicity of the accreted material was [Fe/H] = -0.25, in line with ambient value at the nova galacto-centric distance. Additional spectroscopic and photometric observations at days +477 and +831 show the nova returned to the brightness level of the progenitor and to have resumed the accretion onto the white dwarf.

Model Atmospheres for Novae in Outburst: Summary of Research

NASA Technical Reports Server (NTRS)

Hauschildt, Peter H.

1999-01-01

This paper presents a final report and summary of research on Model Atmospheres for Novae in Outburst. Some of the topics include: 1) Detailed NLTE (non-local thermodynamic equilibrium) Model Atmospheres for Novae during Outburst: II. Modeling optical and ultraviolet observations of Nova LMC 1988 #1; 2) A Non-LTE Line-Blanketed Stellar Atmosphere Model of the Early B Giant epsilon CMa; 3) Spectroscopy of Low Metallicity Stellar atmospheres; 4) Infrared Colors at the Stellar/Substellar Boundary; 5) On the abundance of Lithium in T CrB; 6) Numerical Solution of the Expanding Stellar Atmosphere Problem; and 7) The NextGen Model Atmosphere grid for 3000 less than or equal to T (sub eff) less than or equal to 10000K.

Dust Evolution in Nova Cassiopeia 1993

NASA Astrophysics Data System (ADS)

Eyres, S. P. S.; Evans, A.; Geballe, T. R.; Davies, J. K.; Rawlings, J. M. C.

1997-07-01

We present UKIRT spectroscopy of Nova Cassiopeia 1993 (= V705 Cas) in KLNQ bands, taken in 1994 and 1995. Fitting the continuum indicates a dust temperature T ˜ 740 750 K in the latter part of 1994; this is similar to earlier measurements, and consistent with the “isothermal” behaviour observed in novae with optically thick dust shells. The β-index drops from 0.8 to 0.4 over the same period. This suggests grain growth; grain diameter increases from < 0.54 µm around day 256, to > 0.57 µm by day 342. The UIR features differ from those in other Galactic sources, and are similar to those in V842 Cen. This suggests fundamental differences between the UIR carriers, or environments, in novae and other Galactic sources. The silicate feature is consistent with an amorphous structure, in contrast to previous novae. We believe that grains in V705 Cas form two populations: silicates, and hydrocarbons.

Observations and Analysis of the GK Persei Nova Shell and its "Jet-like" Feature

NASA Astrophysics Data System (ADS)

Harvey, E.; Redman, M. P.; Boumis, P.; Akras, S.

2015-12-01

GK Persei (1901, the "Firework Nebula") is an old but bright nova remnant that offers a chance to probe the physics and kinematics of nova shells. The kinematics in new and archival longslit optical echelle spectra were analysed using the SHAPE software. New imaging from the Aristarchos telescope continues to track the proper motion, extinction and structural evolution of the knots, which have been observed intermittently over several decades. We present for the first time, kinematical constraints on a large faint "jet" feature, that was previously detected beyond the shell boundary. These observational constraints allow for the generation of models for individual knots, interactions within knot complexes, and the "jet" feature. Put together, and taking into account dwarf-nova accelerated winds emanating from the central source, these data and models give a deeper insight into the GK Per nova remnant as a whole.

Gamma-Ray Emission Concurrent with the Nova in the Symbiotic Binary V407 Cygni

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2010-08-13

Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here in this paper, we report the Fermi Large Area Telescope detection of variable γ-ray emission (0.1 to 10 billion electron volts) from the recently detected optical nova of the symbiotic star V407 Cygni. We propose that the material of the nova shell interacts with the dense ambient medium of the red giant primary and that particlesmore » can be accelerated effectively to produce π 0 decay γ-rays from proton-proton interactions. Lastly, emission involving inverse Compton scattering of the red giant radiation is also considered and is not ruled out.« less

NuSTAR and Swift Observations of the Dwarf Nova Z Camelpardalis in a Standstill

NASA Astrophysics Data System (ADS)

Mukai, Koji; Sokoloski, Jennifer; Nelson, Thomas; Luna, Gerardo Juan Manuel; Ringwald, Frederick

2018-01-01

Dwarf nova outbursts are dramatic increases in the optical/UV emission from the accretion disks surrounding non-magnetic, or weakly magnetic, white dwarfs, and they are believed to be caused by disk instabilities. During the optical outburst, the optically thin X-rays originating from the boundary layer between the disk and the white dwarf are known to become fainter and softer. However, during an outburst, neither the disk nor the boundary layer has the time to settle into a steady state, exhibiting clear hysteresis effects instead. The Z Cam-type dwarf novae exhibit a rare, third state called standstill, lasting several months to several years, at an optical brightness roughly one magnitude below outburst peak. A standstill is therefore an ideal opportunity to study a high-state disk while minimizing the hysteresis effects. Here we report our NuSTAR and Swift observations of the prototype, Z Cam, in late September, 2017, roughly 6 months into its most recent standstill episode. To the best of our knowledge, this is the first pointed X-ray observation of a Z Cam-type object in a standstill, and our preliminary analysis suggests Z Cam in standstill has X-ray properties broadly similar to those seen during past outbursts. We will describe these results and discuss implications for the disk physics.

The Radio Light Curve of the Gamma-Ray Nova in V407 CYG: Thermal Emission from the Ionized Symbiotic Envelope, Devoured from Within by the Nova Blast

NASA Technical Reports Server (NTRS)

Chomiuk, Laura; Krauss, Miriam I.; Rupen, Michael P.; Nelson, Thomas; Roy, Nirupam; Sokoloski, Jennifer L.; Mukai, Koji; Munari, Ulisse; Mioduszewski, Amy; Weston, Jeninfer;

New disk nova candidate in M 31

NASA Astrophysics Data System (ADS)

Henze, M.; Pietsch, W.; Burwitz, V.; Rodriguez, J.; Bochinski, J.; Busuttil, R.; Haswell, C. A.; Holmes, S.; Kolb, U.

2012-02-01

We report the discovery of a possible nova in the south-western disk of M 31 on a 5x120s dithered stacked CCD image obtained with the Open University PIRATE Planewave CDK17 0.43m Dall-Kirkham f/6.7 telescope at the Observatorio Astronomico de Mallorca (Costitx, Spain), using an SBIG STX 16803 CCD Camera (with a Kodak 4k x 4k chip with 9 microns sq. pixels) and Baader clear filter, on 2012 Feb 15.803 UT with a R magnitude of 17.5 (accuracy of 0.2 mag).

ASASSN-16dt and ASASSN-16hg: Promising candidate period bouncers

NASA Astrophysics Data System (ADS)

Kimura, Mariko; Isogai, Keisuke; Kato, Taichi; Taguchi, Kenta; Wakamatsu, Yasuyuki; Hambsch, Franz-Josef; Monard, Berto; Myers, Gordon; Dvorak, Shawn; Starr, Peter; Brincat, Stephen M.; de Miguel, Enrique; Ulowetz, Joseph; Itoh, Hiroshi; Stone, Geoff; Nogami, Daisaku

2018-06-01

We present optical photometry of superoutbursts that occurred in 2016 of two WZ Sge-type dwarf novae (DNe), ASASSN-16dt and ASASSN-16hg. Their light curves showed a dip in brightness between the first plateau stage with no ordinary superhumps (or early superhumps) and the second plateau stage with ordinary superhumps. We find that the dip is produced by the slow evolution of the 3 : 1 resonance tidal instability and that it would likely be observed in low mass-ratio objects. An estimated mass ratio (q ≡ M2/M1) from the period of developing (stage A) superhumps [0.06420(3) d] was 0.036(2) in ASASSN-16dt. Additionally, its superoutburst has many properties similar to those in other low-q WZ Sge-type DNe: long-lasting stage-A superhumps, small superhump amplitudes, long delay of ordinary-superhump appearances, and a slow decline rate in the plateau stage with superhumps. Its very small mass ratio and observational characteristics suggest that this system is one of the best candidates for a period bouncer—a binary accounting for the missing population of post-period minimum cataclysmic variables. Although it is not clearly verified due to the lack of detection of stage-A superhumps, ASASSN-16hg might be a possible candidate for period bouncers on the basis of the morphology of its light curves and the small superhump amplitudes. Many outburst properties of period bouncer candidates would originate from the small tidal effects of their secondary stars.

ASASSN-16dt and ASASSN-16hg: Promising candidate period bouncers

NASA Astrophysics Data System (ADS)

Kimura, Mariko; Isogai, Keisuke; Kato, Taichi; Taguchi, Kenta; Wakamatsu, Yasuyuki; Hambsch, Franz-Josef; Monard, Berto; Myers, Gordon; Dvorak, Shawn; Starr, Peter; Brincat, Stephen M.; de Miguel, Enrique; Ulowetz, Joseph; Itoh, Hiroshi; Stone, Geoff; Nogami, Daisaku

2018-04-01

We present optical photometry of superoutbursts that occurred in 2016 of two WZ Sge-type dwarf novae (DNe), ASASSN-16dt and ASASSN-16hg. Their light curves showed a dip in brightness between the first plateau stage with no ordinary superhumps (or early superhumps) and the second plateau stage with ordinary superhumps. We find that the dip is produced by the slow evolution of the 3 : 1 resonance tidal instability and that it would likely be observed in low mass-ratio objects. An estimated mass ratio (q ≡ M2/M1) from the period of developing (stage A) superhumps [0.06420(3) d] was 0.036(2) in ASASSN-16dt. Additionally, its superoutburst has many properties similar to those in other low-q WZ Sge-type DNe: long-lasting stage-A superhumps, small superhump amplitudes, long delay of ordinary-superhump appearances, and a slow decline rate in the plateau stage with superhumps. Its very small mass ratio and observational characteristics suggest that this system is one of the best candidates for a period bouncer—a binary accounting for the missing population of post-period minimum cataclysmic variables. Although it is not clearly verified due to the lack of detection of stage-A superhumps, ASASSN-16hg might be a possible candidate for period bouncers on the basis of the morphology of its light curves and the small superhump amplitudes. Many outburst properties of period bouncer candidates would originate from the small tidal effects of their secondary stars.

Spectral and Timing Investigations of Dwarf Novae Selected in Hard X-Rays

NASA Technical Reports Server (NTRS)

Thorstensen, John; Remillard, Ronald A.

2000-01-01

There are 9 dwarf novae (DN) among the 43 cataclysmic variables (accreting white dwarfs in close binary systems) that were detected during the HEAO-1 all-sky X-ray survey (1977-1979). On the other hand, there are roughly one hundred dwarf novae that are closer and/or optically brighter and yet they were not detected as hard X-ray sources. Two of the HEAO-1 DN show evidence for X-ray pulsations that imply strong magnetic fields on the white dwarf surface, and magnetic CVs are known to be strong X-ray sources. However, substantial flux in hard X-rays may be caused by non-magnetic effects, such as an optically thin boundary layer near a massive white dwarf. We proposed RXTE observations to measure plasma temperatures and to search for X-ray pulsations. The observations would distinguish whether these DN belong to one of (rare) magnetic subclasses. For those that do not show pulsations, the observations support efforts to define empirical relations between X-ray temperature, the accretion rate, and the mass of the white dwarf. The latter is determined via optical studies of the dynamics of the binary constituents.

A Light-curve Analysis of Gamma-Ray Nova V959 Mon: Distance and White Dwarf Mass

NASA Astrophysics Data System (ADS)

Hachisu, Izumi; Kato, Mariko

2018-05-01

V959 Mon is a nova detected in gamma-rays. It was discovered optically about 50 days after the gamma-ray detection owing to its proximity to the Sun. The nova’s speed class is unknown because of the lack of the earlier half of its optical light curve and a short supersoft X-ray phase due to eclipse by the disk rim. Using the universal decline law and time-stretching method, we analyzed the data on V959 Mon and obtained nova parameters. We estimated the distance modulus in the V band to be (m ‑ M) V = 13.15 ± 0.3 for the reddening of E(B ‑ V) = 0.38 ± 0.01 by directly comparing it with novae of a similar type—LV Vul, V1668 Cyg, IV Cep, and V1065 Cen. The distance to V959 Mon is 2.5 ± 0.5 kpc. If we assume that the early phase of the light curve of V959 Mon is the same as that of time-stretched light curves of LV Vul, our model fitting of the light curve suggests that the white dwarf (WD) mass is 0.9–1.15 M ⊙, which is consistent with a neon nova identification. At the time of gamma-ray detection the photosphere of the nova envelope extends to 5–8 R ⊙ (about two or three times the binary separation) and the wind mass-loss rate is (3{--}4)× {10}-5 {M}ȯ yr‑1. The period of hard X-ray emission is consistent with the time of appearance of the companion star from the nova envelope. The short supersoft X-ray turnoff time is consistent with the epoch when the WD photosphere shrank to behind the rising disk rim, which occurred 500 days before nuclear burning turned off.

Six months of multiwavelength follow-up of the tidal disruption candidate ASASSN-14li and implied TDE rates from ASAS-SN

DOE PAGES

Holoien, Thomas W. -S.; Kochanek, C. S.; Prieto, J. L.; ...

2015-11-25

In this paper, we present ground-based and Swift photometric and spectroscopic observations of the candidate tidal disruption event (TDE) ASASSN-14li, found at the centre of PGC 043234 (d ≃ 90 Mpc) by the All-Sky Automated Survey for SuperNovae (ASAS-SN). The source had a peak bolometric luminosity of L ≃ 10 44 erg s -1 and a total integrated energy of E ≃ 7 × 10 50 erg radiated over the ~6 months of observations presented. The UV/optical emission of the source is well fitted by a blackbody with roughly constant temperature of T ~ 35 000 K, while the luminositymore » declines by roughly a factor of 16 over this time. The optical/UV luminosity decline is broadly consistent with an exponential decline, L∝e -t/t0, with t 0 ≃ 60 d. ASASSN-14li also exhibits soft X-ray emission comparable in luminosity to the optical and UV emission but declining at a slower rate, and the X-ray emission now dominates. Spectra of the source show broad Balmer and helium lines in emission as well as strong blue continuum emission at all epochs. Finally, we use the discoveries of ASASSN-14li and ASASSN-14ae to estimate the TDE rate implied by ASAS-SN, finding an average rate of r ≃ 4.1 × 10 -5 yr -1 per galaxy with a 90 per cent confidence interval of (2.2–17.0) × 10 -5 yr -1 per galaxy. ASAS-SN found roughly 1 TDE for every 70 Type Ia supernovae in 2014, a rate that is much higher than that of other surveys.« less

Six months of multiwavelength follow-up of the tidal disruption candidate ASASSN-14li and implied TDE rates from ASAS-SN

NASA Astrophysics Data System (ADS)

Holoien, T. W.-S.; Kochanek, C. S.; Prieto, J. L.; Stanek, K. Z.; Dong, Subo; Shappee, B. J.; Grupe, D.; Brown, J. S.; Basu, U.; Beacom, J. F.; Bersier, D.; Brimacombe, J.; Danilet, A. B.; Falco, E.; Guo, Z.; Jose, J.; Herczeg, G. J.; Long, F.; Pojmanski, G.; Simonian, G. V.; Szczygieł, D. M.; Thompson, T. A.; Thorstensen, J. R.; Wagner, R. M.; Woźniak, P. R.

2016-01-01

We present ground-based and Swift photometric and spectroscopic observations of the candidate tidal disruption event (TDE) ASASSN-14li, found at the centre of PGC 043234 (d ≃ 90 Mpc) by the All-Sky Automated Survey for SuperNovae (ASAS-SN). The source had a peak bolometric luminosity of L ≃ 1044 erg s-1 and a total integrated energy of E ≃ 7 × 1050 erg radiated over the ˜6 months of observations presented. The UV/optical emission of the source is well fitted by a blackbody with roughly constant temperature of T ˜ 35 000 K, while the luminosity declines by roughly a factor of 16 over this time. The optical/UV luminosity decline is broadly consistent with an exponential decline, L∝ e^{-t/t_0}, with t0 ≃ 60 d. ASASSN-14li also exhibits soft X-ray emission comparable in luminosity to the optical and UV emission but declining at a slower rate, and the X-ray emission now dominates. Spectra of the source show broad Balmer and helium lines in emission as well as strong blue continuum emission at all epochs. We use the discoveries of ASASSN-14li and ASASSN-14ae to estimate the TDE rate implied by ASAS-SN, finding an average rate of r ≃ 4.1 × 10-5 yr-1 per galaxy with a 90 per cent confidence interval of (2.2-17.0) × 10-5 yr-1 per galaxy. ASAS-SN found roughly 1 TDE for every 70 Type Ia supernovae in 2014, a rate that is much higher than that of other surveys.

Multiwavelength monitoring of the dwarf nova VW Hydri. IV - Voyager observations

NASA Technical Reports Server (NTRS)

Polidan, R. S.; Holberg, J. B.

1987-01-01

Results from Voyager far-ultraviolet (500-1200 A) observations of the dwarf nova VW Hyi are presented as part of a coordinated, multiwavelength program. Data from one normal outburst and one superoutburst are discussed in detail. Far-ultraviolet (1050 A) light curves are produced showing a significant delay (0.5 day) in the rise to maximum at 1050 A with respect to optical wavelength, followed by a simultaneous decline. The superoutburst data show a distinct double-peaked light curve with the first rise and decline closely resembling that of a normal outburst. These data suggest that the rise to supermaximum in the far-ultraviolet is also delayed with respect to optical wavelengths. The spectral distribution of VW Hyi shows the steeply falling spectrum shortward of 1200 A, characteristic of dwarf novae in outburst and absorption features at 985 (N III, C III and Ly gamma) and 1030 (Ly beta and O VI). No flux shortward of 912 A was detected in VW Hyi.

Observational constraints on black hole accretion disks

NASA Technical Reports Server (NTRS)

Liang, Edison P.

1994-01-01

We review the empirical constraints on accretion disk models of stellar-mass black holes based on recent multiwavelength observational results. In addition to time-averaged emission spectra, the time evolutions of the intensity and spectrum provide critical information about the structure, stability, and dynamics of the disk. Using the basic thermal Keplerian disk paradigm, we consider in particular generalizations of the standard optically thin disk models needed to accommodate the extremely rich variety of dynamical phenomena exhibited by black hole candidates ranging from flares of electron-positron annihilations and quasiperiodic oscillations in the X-ray intensity to X-ray novae activity. These in turn provide probes of the disk structure and global geometry. The goal is to construct a single unified framework to interpret a large variety of black hole phenomena. This paper will concentrate on the interface between basic theory and observational data modeling.

On the Accretion Rates of SW Sextantis Nova-like Variables

NASA Astrophysics Data System (ADS)

Ballouz, Ronald-Louis; Sion, Edward M.

2009-06-01

We present accretion rates for selected samples of nova-like variables having IUE archival spectra and distances uniformly determined using an infrared method by Knigge. A comparison with accretion rates derived independently with a multiparametric optimization modeling approach by Puebla et al. is carried out. The accretion rates of SW Sextantis nova-like systems are compared with the accretion rates of non-SW Sextantis systems in the Puebla et al. sample and in our sample, which was selected in the orbital period range of three to four and a half hours, with all systems having distances using the method of Knigge. Based upon the two independent modeling approaches, we find no significant difference between the accretion rates of SW Sextantis systems and non-SW Sextantis nova-like systems insofar as optically thick disk models are appropriate. We find little evidence to suggest that the SW Sex stars have higher accretion rates than other nova-like cataclysmic variables (CVs) above the period gap within the same range of orbital periods.

Late stages in the evolution of classical novae

NASA Technical Reports Server (NTRS)

Starrfield, S.; Krautter, J.; Sonneborn, G.; Shore, S. N.; Wagner, R. M.; Austin, S.; Saizar, P.; Ferland, G.; Wade, R.; Gehrz, R. D.

1990-01-01

We have begun a study of the long term evolution of novae in outburst in order to determine the means by which they return in quiescence when nuclear burning has ended. This project involves both IUE and optical observations and theoretical predictions. Recently, in the initial observational part of this project, we have obtained IUE Short Wavelength Prime (SWP) spectra of GQ Mus 1983 and QU Vul 1984. Each spectrum was a 16 hour exposure using a combined US1 plus Vilspa shift. No novae have been studied in the UV for as long as QU Vul and GQ Mus and observations of their spectral evolution are providing unique data on the turn-off time scale. We have also obtained the spectra of old novae from the IUE archives in order to compare and contrast the existing spectra with those of GQ Mus and Qu Vul. The theoretical prediction is that a nova should be very hot just before turnoff but x ray observations from EXOSAT do not confirm this prediction.

Mass retention efficiencies of He accretion onto carbon-oxygen white dwarfs and type Ia supernovae

NASA Astrophysics Data System (ADS)

Wu, C.; Wang, B.; Liu, D.; Han, Z.

2017-07-01

Context. Type Ia supernovae (SNe Ia) play a crucial role in studying cosmology and galactic chemical evolution. They are thought to be thermonuclear explosions of carbon-oxygen white dwarfs (CO WDs) when their masses reach the Chandrasekar mass limit in binaries. Previous studies have suggested that He novae may be progenitor candidates of SNe Ia. However, the mass retention efficiencies during He nova outbursts are still uncertain. Aims: In this article, we aim to study the mass retention efficiencies of He nova outbursts and to investigate whether SNe Ia can be produced through He nova outbursts. Methods: Using the stellar evolution code Modules for Experiments in Stellar Astrophysics, we simulated a series of multicycle He-layer flashes, in which the initial WD masses range from 0.7 to 1.35 M⊙ with various accretion rates. Results: We obtained the mass retention efficiencies of He nova outbursts for various initial WD masses, which can be used in the binary population synthesis studies. In our simulations, He nova outbursts can increase the mass of the WD to the Chandrasekar mass limit and the explosive carbon burning can be triggered in the center of the WD; this suggests that He nova outbursts can produce SNe Ia. Meanwhile, the mass retention efficiencies in the present work are lower than those of previous studies, which leads to a lower birthrates of SNe Ia through the WD + He star channel. Furthermore, we obtained the elemental abundances distribution at the moment of explosive carbon burning, which can be used as the initial input parameters in studying explosion models of SNe Ia.

Early X- and HE γ-ray emission from the symbiotic recurrent novae V745 Sco & RS Oph.

NASA Astrophysics Data System (ADS)

Delgado, L.; Hernanz, M.

2017-10-01

RS Oph was the first nova for which evidence of particle acceleration during its 2006 outburst was found. In recent years, several nova explosions - eight classical and two symbiotic recurrent novae - have been detected by Fermi/LAT at E>100 MeV. In most cases, this emission has been observed early after the explosion, around the optical maximum, and for a short period of time. The high-energy γ-ray emission is a consequence of π^{0} decay and/or Inverse Compton, which are related to particle (p and e^{-}) acceleration in the strong shock between the nova ejecta and the circumstellar matter. Our aim is to understand the acceleration process through the analysis of contemporaneous X-ray emission, and in particular, through the evolution of the shock wave. A deep analysis of early X-ray observations of the symbiotic recurrent novae V745 Sco (2014) by Swift/XRT, Chandra/HETG and NuStar, and RS Oph (2006) by XMM-Newton/EPIC and RGS, Swift/XRT and BAT and RXTE/PCA is presented taking into account the contemporaneous information from the IR and radio observations. This provides for the first time a global view of the early evolution of a nova remnant and its relationship with particle acceleration.

Opto-mechanical design for transmission optics in cryogenic space instrumentation

NASA Astrophysics Data System (ADS)

Kroes, Gabby; Venema, Lars; Navarro, Ramón

2017-11-01

NOVA is involved in the development and realization of various optical astronomical instruments for groundbased as well as space telescopes, with a focus on nearand mid-infrared instrumentation. NOVA has developed a suite of scientific instruments with cryogenic optics for the ESO VLT and VLTI instruments: VISIR, MIDI, the SPIFFI 2Kcamera for SINFONI, X-shooter and MATISSE. Other projects include the cryogenic optics for MIRI for the James Webb Space Telescope and several E-ELT instruments. Mounting optics is always a compromise between firmly fixing the optics and preventing stresses within the optics. The fixing should ensure mechanical stability and thus accurate positioning in various gravity orientations, temperature ranges, during launch, transport or earthquake. On the other hand, the fixings can induce deformations and sometimes birefringence in the optics and thus cause optical errors. Even cracking or breaking of the optics is a risk, especially when using brittle infrared optical materials at the cryogenic temperatures required in instruments for infrared astronomy, where differential expansion of various materials amounts easily to several millimeters per meter. Special kinematic mounts are therefore needed to ensure both accurate positioning and low stress. This paper concentrates on the opto-mechanical design of optics mountings, especially for large transmission optics in cryogenic circumstances in space instruments. It describes the development of temperature-invariant ("a-thermal") kinematic designs, their implementation in ground based instrumentation and ways to make them suitable for space instruments.

Synthetic Spectral Analysis of the Far Ultraviolet Spectra of the Old Nova HR Del

NASA Astrophysics Data System (ADS)

Robertson, Jordan; Sion, E.

2012-05-01

We present a synthetic spectral analysis of the archival IUE far ultraviolet spectra of the post-nova, HR Del (Nova Del 1967). The system has an estimated white dwarf mass of 0.55 Msun (Ritter and Kolb 2003), orbital period P_orb = 0.214165 days, estimated orbital inclination of 40 degrees (Keurster 1988) and distance determinations in the literature ranging from 970 pc to 285 pc. The spectra reveal P Cygni profiles indicative of wind outflow from the disk and closely resemble the IUE spectra of UX UMa nova-likes, which have never had recorded outbursts. We de-reddened the archival IUE spectra using E(B-V) = 0.16. Our synthetic spectral analysis utilized optically thick, steady state accretion disk models and white dwarf model atmospheres that we constructed using TLUSTY and SYNSPEC (Hubeny 1988, Hubeny and Lanz (1995). Our input parameters were the white dwarf mass, inclination and a range of accretion rates for which we found the best-fitting model. We report the results of our model fitting and compare HR Del with other post-novae at comparable times past their nova outburst. This work was supported by NSF grant 0807892 to Villanova University

Optical Variability Analysis of UU Aqr - an Eclipsing Nova-like System

NASA Astrophysics Data System (ADS)

Khruzina, T.; Katysheva, N.; Golysheva, P.; Shugarov, S.

2015-12-01

By using our photometric observations of nova-like system UU Aqr with unstable light curve during a few nights, we plotted phase-folded light curves and calculated a model of the system. We show that the complicated character of light curves can be explained by the spiral arms in the disk. We decomposed the syntesis photometric curve into separated components as accretion disk, white and red dwarf, hot line.

Fermi-LAT Observations of Continued Gamma-ray Activity from Nova ASASSN-16ma

NASA Astrophysics Data System (ADS)

Li, Kwan-Lok; Chomiuk, Laura; Strader, Jay; Cheung, C. C.; Jean, P.; Shore, S. N.; Fermi Large Area Telescope Collaboration

2016-11-01

Following the report of a sudden gamma-ray onset detection of nova ASASSN-16ma coincident with the optical peak of 5.5 mag on November 8 (ATel #9736), ASASSN-16ma was observed to slowly decrease in gamma-rays but has remained bright enough to be detectable with Fermi-LAT over the last 9 days (test statistic, TS > 10 per day, except for November 17 with TS=5).

X-ray nova MAXI J1828-249. Evolution of the broadband spectrum during its 2013-2014 outburst

NASA Astrophysics Data System (ADS)

Grebenev, S. A.; Prosvetov, A. V.; Burenin, R. A.; Krivonos, R. A.; Mescheryakov, A. V.

2016-02-01

Based on data from the SWIFT, INTEGRAL, MAXI/ISS orbital observatories, and the ground-based RTT-150 telescope, we have investigated the broadband (from the optical to the hard X-ray bands) spectrum of the X-ray nova MAXI J1828-249 and its evolution during the outburst of the source in 2013-2014. The optical and infrared emissions from the nova are shown to be largely determined by the extension of the power-law component responsible for the hard X-ray emission. The contribution from the outer cold regions of the accretion disk, even if the X-ray heating of its surface is taken into account, turns out to be moderate during the source's "high" state (when a soft blackbody emission component is observed in the X-ray spectrum) and is virtually absent during its "low" ("hard") state. This result suggests that much of the optical and infrared emissions from such systems originates in the same region of main energy release where their hard X-ray emission is formed. This can be the Compton or synchro-Compton radiation from a high-temperature plasma in the central accretion disk region puffed up by instabilities, the synchrotron radiation from a hot corona above the disk, or the synchrotron radiation from its relativistic jets.

Nonradial Pulsations in Post-outburst Novae

NASA Astrophysics Data System (ADS)

Wolf, William M.; Townsend, Richard H. D.; Bildsten, Lars

2018-03-01

After an optical peak, a classical or recurrent nova settles into a brief (days to years) period of quasi-stable thermonuclear burning in a compact configuration nearly at the white dwarf (WD) radius. During this time, the underlying WD becomes visible as a strong emitter of supersoft X-rays. Observations during this phase have revealed oscillations in the X-ray emission with periods on the order of tens of seconds. A proposed explanation for the source of these oscillations is internal gravity waves excited by nuclear reactions at the base of the hydrogen-burning layer. In this work, we present the first models exhibiting unstable surface g-modes with periods similar to oscillation periods found in galactic novae. However, when comparing mode periods of our models to the observed oscillations of several novae, we find that the modes that are excited have periods shorter than that observed.

GW LIBRAE: STILL HOT EIGHT YEARS POST-OUTBURST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szkody, Paula; Mukadam, Anjum S.; Gänsicke, Boris T.

We report continued Hubble Space Telescope ( HST ) ultraviolet spectra and ground-based optical photometry and spectroscopy of GW Librae eight years after its largest known dwarf nova outburst in 2007. This represents the longest cooling timescale measured for any dwarf nova. The spectra reveal that the white dwarf still remains about 3000 K hotter than its quiescent value. Both ultraviolet and optical light curves show a short period of 364–373 s, similar to one of the non-radial pulsation periods present for years prior to the outburst, and with a similar large UV/optical amplitude ratio. A large modulation at amore » period of 2 hr (also similar to that observed prior to outburst) is present in the optical data preceding and during the HST observations, but the satellite observation intervals did not cover the peaks of the optical modulation, and so it is not possible to determine its corresponding UV amplitude. The similarity of the short and long periods to quiescent values implies that the pulsating, fast spinning white dwarf in GW Lib may finally be nearing its quiescent configuration.« less

On the Nature of CP Pup

NASA Technical Reports Server (NTRS)

Mason, E.; Orio, M.; Mukai, K.; Bianchini, A.; deMartino, D.; diMille, F.; Williams, R. E.

2013-01-01

We present new X-ray and optical spectra of the old nova CP Pup (nova Pup 1942) obtained with Chandra and the CTIO 4m telescope. The X-ray spectrum reveals a multi-temperature optically thin plasma reaching a maximum temperature of 36+19 keV 16 absorbed by local complex neutral material. The time resolved optical spectroscopy confirms the presence of the 1.47 hr period, with cycle-to-cycle amplitude changes, as well as of an additional long term modulation which is suggestive either of a longer pe- riod or of non-Keplerian velocities in the emission line regions. These new observational facts add further support to CP Pup as a magnetic cataclysmic variable (mCV). We compare the mCV and the non-mCV scenarios and while we cannot conclude whether CP Pup is a long period system, all observational evidences point at an intermediate polar (IP) type CV.

HUBBLE SEES CHANGES IN GAS SHELL AROUND NOVA CYGNI 1992

NASA Technical Reports Server (NTRS)

2002-01-01

The European Space Agency's ESA Faint Object Camera utilizing the corrective optics provided by NASA's COSTAR (Corrective Optics Space Telescope Axial Replacement), has given astronomers their best look yet at a rapidly ballooning bubble of gas blasted off a star. The shell surrounds Nova Cygni 1992, which erupted on February 19, 1992. A nova is a thermonuclear explosion that occurs on the surface of a white dwarf star in a double star system. The new HST image [right] reveals an elliptical and slightly lumpy ring-like structure. The ring is the edge of a bubble of hot gas blasted into space by the nova. The shell is so thin that the FOC does not resolve its true thickness, even with HST's restored vision. An HST image taken on May 31 1993, [left] 467 days after the explosion, provided the first glimpse of the ring and a mysterious bar-like structure. But the image interpretation was severely hampered by HST's optical aberration, that scattered light from the central star which contaminated the ring's image. A comparison of the pre and post COSTAR/FOC images reveals that the ring has evolved in the seven months that have elapsed between the two observations. The ring has expanded from a diameter of approximately 74 to 96 billion miles. The bar-like structure seen in the earlier HST image has disappear. These changes might confirm theories that the bar was produced by a dense layer of gas thrown off in the orbital plane of the double star system. The gas has subsequently grown more tenuous and so the bar has faded. The ring has also grown noticeably more oblong since the earlier image. This suggests the hot gas is escaping more rapidly above and below the system's orbital plane. As the gas continues escaping the ring should grow increasingly egg-shaped in the coming years. HST's newly improved sensitivity and high resolution provides a unique opportunity to understand the novae by resolving the effects of the explosion long before they can be resolved in ground based telescopes. Nova Cygni is 10,430 light years away (as measured directly from the ring's diameter), and located in the summer constellation Cygnus the Swan. Credit: F. Paresce, R. Jedrzejewski (STScI) NASA/ESA PHOTO RELEASE NO.: STScI-PR94-06

Suzaku Observation of the Dwarf Nova V893 Scorpii: The Discovery of a Partial X-Ray Eclipse

NASA Technical Reports Server (NTRS)

Mukai, Koji; Zietsman, E.; Still, M.

2008-01-01

V893 Sco is an eclipsing dwarf nova that had attracted little attention from X-ray astronomers until it was proposed as the identification of an RXTE all-sky slew survey (XSS) source. Here we report on the po inted X-ray observations of this object using Suzaku. We confirm V893 Sco to be X-ray bright, whose spectrum is highly absorbed for a dwar f nova. We have also discovered a partial X-ray eclipse in V893 Sco. This is the first time that a partial eclipse is seen in Xray light c urves of a dwarf nova. We have successfully modeled the gross features of the optical and X-ray eclipse light curves using a boundary layer geometry of the X-ray emission region. Future observations may lead to confirmation of this basic picture, and allow us to place tight co nstraints on the size of the X-ray emission region. The partial X-ray eclipse therefore should make V893 Sco a key object in understanding the physics of accretion in quiescent dwarf nova.

Coatings for high energy applications. The Nova laser

NASA Astrophysics Data System (ADS)

Wirtenson, G. R.

The combined requirements of energy density, multiple wavelength, and aperture make the coatings for the Nova Inertial Confinement Fusion (ICF) laser unique. This ten beam neodymium glass laser system, built at the Lawrence Livermore National Laboratory (LLNL), has over a thousand major optical components; some larger than one meter in diameter and weighing 380 Kg. The laser operates at 1054 nm and can be frequency doubled to 527 nm or tripled to 351 nm by means of full aperture potassium dihydrogen phosphate (KDP) crystal arrays. The 1.0 nsec fluence varies along the laser chain, sometimes reaching values as high as 16 J/cm(2) at the input lens to one of the spatial filters. The design specifications of this massive optical system were changed several times as the state-of-the-art advanced. Each change required redesign of the optical coatings even as vendors were preparing for production runs. Frequency conversion to include shorter wavelengths mandated the first major coating redesign and was followed almost immediately by a second redesign to reduce solarization effects in borosilicate crown glass. The conventional thermal evaporation process although successful for the deposition of mirror coatings, was not able to produce antireflection coatings able to survive the locally high chain fluences. As a consequence it became necessary to develop another technique. Solution produced coatings were developed having transmissions exceeding 99% per part and damage threshold values equal to the bare substrate. The unique requirement of the Nova laser necessitated special deposition and metrology equipment. These programmatic developments will be reviewed in the context of the cooperative working relationship developed between LLNL and its vendors. It was this excellent relationship which has enabled LLNL to obtain these highly specialized coatings for the Nova laser.

Photometric evolution of seven recent novae and the double-component characterizing the light curve of those emitting in gamma rays

NASA Astrophysics Data System (ADS)

Munari, U.; Hambsch, F.-J.; Frigo, A.

2017-08-01

The BVI light curves of seven recent novae (I.e. V1534 Sco, V1535 Sco, V2949 Oph, V3661 Oph, MASTER OT J010603.18-744715.8, TCP J1734475-240942 and ASASSN-16ma) have been extensively mapped with daily robotic observations from Atacama (Chile): five belong to the Galactic bulge, one to the Small Magellanic Cloud and another is a Galactic disc object. The two programme novae detected in γ-rays by Fermi-LAT (I.e. TCP J1734475-240942 and ASASSN-16ma) are bulge objects with unevolved companions. They distinguish themselves by showing a double-component optical light curve. The first component to develop is the fireball from freely expanding, ballistic-launched ejecta, with a time of passage through maximum that is strongly dependent on wavelength (˜1 d delay between the B and I bands). The second component, emerging simultaneously with the nova detection in γ-rays, evolves at a slower pace, its optical brightness being proportional to the γ-ray flux, and its passage through maximum not dependent on wavelength. The fact that γ-rays are detected at a flux level that differs by four times from novae at the distance of the bulge seems to suggest that γ-ray emission is not a widespread property of normal novae. We discuss the advantages offered by high-quality photometric observations collected with only one telescope (as opposed to data provided by a number of different instruments). We also observe the effects of the wavelength dependence of fireball expansion, the recombination in the flashed wind of a giant companion, the subtle presence of hiccups and plateaus, and the super-soft X-ray emission and its switch-off. Four programme novae (V2949 Oph, V3661 Oph, TCP J18102829-2729590 and ASASSN-16ma) have normal dwarf companions: V1534 Sco contains an M3 III giant, V1535 Sco a K-type giant and MASTER OT J010603.18-744715.8 a subgiant. We also comment briefly on the maximum absolute magnitude relation with decline time (MMRD).

Circumstellar Dust in Symbiotic Novae

NASA Astrophysics Data System (ADS)

Jurkic, T.; Kotnik-Karuza, D.

2015-12-01

We present a model of inner dust regions around the cool Mira component of the two symbiotic novae, RR Tel and HM Sge, based on the near-IR photometry, ISO spectra and mid-IR interferometry. The dust properties were determined using the DUSTY code. A compact circumstellar silicate dust shell with inner dust shell temperatures between 900 K and 1300 K and of moderate optical depth can explain all the observations. RR Tel shows the presence of an equatorially enhanced dust density during minimum obscuration. Obscuration events are explained by an increase in optical depth caused by the newly condensed dust. The mass loss rates are significantly higher than in intermediate-period single Miras but in agreement with longer-period O-rich AGB stars.

The Shape of Long Outbursts in U Gem Type Dwarf Novae from AAVSO Data

NASA Technical Reports Server (NTRS)

Cannizzo, John K.

2012-01-01

We search the American Association of Variable Star Observers (AAVSO) archives of the two best studied dwarf novae in an attempt to find light curves for long out bursts that are extremely well-characterized. The systems are U Gem and S8 Cyg. Our goal is to search for embedded precursors such as those that have been found recently in the high fidelity Kepler data for superoutbursts of some members of the 8U UMa subclass of dwarf novae. For the vast majority of AAV80 data, the combination of low data cadence and large errors associated with individual measurements precludes one from making any strong statement about the shape of the long outbursts. However, for a small number of outbursts, extensive long term monitoring with digital photometry yields high fidelity light curves. We report the finding of embedded precursors in two of three candidate long outbursts. This reinforces van Paradijs' finding that long outbursts in dwarf novae above the period gap and superoutbursts in systems below the period gap constitute a unified class. The thermal-tidal instability to account for superoutbursts in the SU UMa stars predicts embedded precursors only for short orbital period dwarf novae, therefore the presence of embedded precursors in long orbital period systems - U Gem and SS Cyg - argues for a more general mechanism to explain long outbursts.

Spectroscopic classification of X-ray sources in the Galactic Bulge Survey

NASA Astrophysics Data System (ADS)

Wevers, T.; Torres, M. A. P.; Jonker, P. G.; Nelemans, G.; Heinke, C.; Mata Sánchez, D.; Johnson, C. B.; Gazer, R.; Steeghs, D. T. H.; Maccarone, T. J.; Hynes, R. I.; Casares, J.; Udalski, A.; Wetuski, J.; Britt, C. T.; Kostrzewa-Rutkowska, Z.; Wyrzykowski, Ł.

2017-10-01

We present the classification of 26 optical counterparts to X-ray sources discovered in the Galactic Bulge Survey. We use (time-resolved) photometric and spectroscopic observations to classify the X-ray sources based on their multiwavelength properties. We find a variety of source classes, spanning different phases of stellar/binary evolution. We classify CX21 as a quiescent cataclysmic variable (CV) below the period gap, and CX118 as a high accretion rate (nova-like) CV. CXB12 displays excess UV emission, and could contain a compact object with a giant star companion, making it a candidate symbiotic binary or quiescent low-mass X-ray binary (although other scenarios cannot be ruled out). CXB34 is a magnetic CV (polar) that shows photometric evidence for a change in accretion state. The magnetic classification is based on the detection of X-ray pulsations with a period of 81 ± 2 min. CXB42 is identified as a young stellar object, namely a weak-lined T Tauri star exhibiting (to date unexplained) UX Ori-like photometric variability. The optical spectrum of CXB43 contains two (resolved) unidentified double-peaked emission lines. No known scenario, such as an active galactic nucleus or symbiotic binary, can easily explain its characteristics. We additionally classify 20 objects as likely active stars based on optical spectroscopy, their X-ray to optical flux ratios and photometric variability. In four cases we identify the sources as binary stars.

Expanded Very Large Array Nova Project Observations of the Classical Nova V1723 Aquilae

NASA Astrophysics Data System (ADS)

Krauss, Miriam I.; Chomiuk, Laura; Rupen, Michael; Roy, Nirupam; Mioduszewski, Amy J.; Sokoloski, J. L.; Nelson, Thomas; Mukai, Koji; Bode, M. F.; Eyres, S. P. S.; O'Brien, T. J.

2011-09-01

We present radio light curves and spectra of the classical nova V1723 Aql obtained with the Expanded Very Large Array (EVLA). This is the first paper to showcase results from the EVLA Nova Project, which comprises a team of observers and theorists utilizing the greatly enhanced sensitivity and frequency coverage of EVLA radio observations, along with observations at other wavelengths, to reach a deeper understanding of the energetics, morphology, and temporal characteristics of nova explosions. Our observations of V1723 Aql span 1-37 GHz in frequency, and we report on data from 14 to 175 days following the time of the nova explosion. The broad frequency coverage and frequent monitoring show that the radio behavior of V1723 Aql does not follow the classic Hubble-flow model of homologous spherically expanding thermal ejecta. The spectra are always at least partially optically thin, and the flux rises on faster timescales than can be reproduced with linear expansion. Therefore, any description of the underlying physical processes must go beyond this simple picture. The unusual spectral properties and light curve evolution might be explained by multiple emitting regions or shocked material. Indeed, X-ray observations from Swift reveal that shocks are likely present.

Expanded Very Large Array Nova Project Observations of the Classical NovaV1723 Aquilae

NASA Technical Reports Server (NTRS)

Krauss, Miriam I.; Chomiuk, Laura; Rupen, Michael; Roy, Nirupam; Mioduszewski, Amy J.; Sokoloski, J. L.; Nelson, Thomas; Mukai, Koji; Bode, M. F.; Eyres, S. P. S.;

The Nova-Dwarf Nova Connection

NASA Astrophysics Data System (ADS)

De Marco, Orsola

The extraordinary discovery that thermonuclear runaway (TNR) processed material lives on the white dwarf (WD) surface in the dwarf nova (DN) system VW Hyi is in direct conflict with the currently accepted model for DNe. The WD in VW Hyi should be continuously buried in solar-abundance material accreted from its fully-convective, low-mass main sequence companion. IT ISNT. There are either subtle metallicity-varying forces at work, or the current theory of DNe is completely wrong. Only by monitoring the abundances of key elements throughout an entire dwarf nova cycle will we be able to observe the rate of change of key abundance ratios by accretion and mixing processes, and hence deduce the relative importance of diffusion (in removing metals), accretion (in adding metals) and (non-party line but possible) local nuclear burning. FUSE is ideal for this task, because its spectral range contains key lines of important elements, because of its high temperature sensitivity and because in its wavelength range, the VW Hyi spectrum is totally dominated by the WD. VW Hyi is the obvious candidate for this project, because we already know that its abundances are indicative of recent TNR processing.

The Early Spectral Evolution of the Classical Nova ASASSN-15th in M33

NASA Astrophysics Data System (ADS)

Wagner, R. Mark; Neric, Marko; Darnley, Matt J.; Williams, Steven; Starrfield, Sumner; Woodward, Charles E.; Prieto, Jose Luis

2016-06-01

During the course of the All Sky Automated Survey for SuperNovae (ASAS-SN) a new transient source designated ASASSN-15th was identified on images of the nearby galaxy M33 obtained with the 14 cm Brutus telescope in Haleakala, Hawaii on 2015 Dec 1.4 UT at V ~ 16.5 mag. Given the location of the transient in M33 and its apparent V magnitude at discovery, the implied absolute visual magnitude was about -8.5 mag suggesting that the transient was a new classical nova outburst in M33. Optical spectroscopy obtained by us on 2015 Dec 2.3 showed broad emission lines of Balmer, Fe II, and Na I D with P Cygni-type line profiles superposed on a blue continuum. The spectrum was consistent with a Fe II-type classical nova in M33 discovered early in the outburst. Subsequent spectra obtained by us on 2015 Dec 10.9 UT showed significant evolution since our first spectrum in that the deep P Cygni-type line profiles seen earlier were now extremely shallow or had almost completely disappeared with the emission component growing in strength. Additional emission lines from O I, Si II, and possibly He I were also present. We obtained optical spectroscopy of ASASSN-15th on 17 epochs between 2015 Dec 1 and 2016 Feb 11 UT with the 2.4 m Hiltner telescope (+OSMOS) of the MDM Observatory, the 2 m fully robotic Liverpool Telescope (+SPRAT), and the 2 x 8.4 m Large Binocular Telescope (+MODS). We will present our spectroscopy and discuss the early evolution of ASASSN-15th in the context of Galactic Fe II-class novae.

Optical Spectroscopy of the Classical Novae V339 Del (2013) and V5668 Sgr (2015 No. 2)

NASA Astrophysics Data System (ADS)

Wagner, R. Mark; Woodward, Charles E.; Starrfield, Sumner; Ilyin, Ilya; Strassmeier, Klaus G.; Page, Kim; Osborne, Julian P.; Beardmore, Andrew P.

2016-01-01

We report the results of optical spectroscopy of the gamma-ray classical novae V339 Del (2013) and V5668 Sgr (PNV J18365700-2855420/Nova Sgr 2015 No. 2) supplemented by UV and X-ray observations obtained with Swift. Our spectra were obtained with the Steward Observatory Bok 2.3 m telescope (+B&C), the MDM 2.4 m Hiltner telescope (+OSMOS), the 6.5 m MMT (+BlueChannel), and the 2 x 8.4 m Large Binocular Telescope (+MODS1 and PEPSI) between 2013 August and 2015 September. The PEPSI spectra cover all or part of the 384-907 nm spectral region at a resolution of up to 270,000 (1 km/s). This is the highest resolution available on any 8-10 m class telescope. V339 Del was discovered on 2015 August 14.58 by Itagaki at V about 6.8. This nova reached a peak magnitude of about 4.3 making it one of the brightest novae of this century. Because of its exceptional brightness it has been observed at a variety of wavelengths and by a host of observatories both on the ground and in space. V5668 Sgr was discovered on 2015 March 15.634 by Seach at a magnitude of 6.0. It subsequently reached a maximum brightness of about 4.0 in late March. High resolution PEPSI spectra obtained in early April show dramatic variations in the multi-component P Cygni-type line profiles. V5668 Sgr was observed to form dust in June thereafter fading to about 13th magnitude. Our recent observations show that it has now evolved into the nebular phase. SS acknowledges partial support from NSF and NASA grants to ASU. CEW acknowledges support from NASA.

High-resolution Interferometric Observations of Nova RS Ophiuchi and a Proposed Unification Model for Persistent Dust Creation in Recurrent Novae

NASA Astrophysics Data System (ADS)

Barry, R. K.; Danchi, W. C.

2008-12-01

We review observations of nova RS Ophiuchi using long-baseline near-infrared and mid-infrared interferometry at three observatories: the Keck Interferometer in the Nulling mode (KIN), the Palomar Testbed Interferometer (PTI), and the Infrared and Optical Telescope Array (IOTA). We discuss these observations in the context of a unifying model of the system that includes an increase in density in the plane of the orbit of the two stars created by a spiral shock wave caused by the motion of the stars through the cool wind of the red giant star. We discuss how recent observations using the Spitzer Space Telescope and the VLTI support this proposed model.

Infrared photometry of Nova Delphini 2013 (=V339 Del) in the first sixty days after its outburst

NASA Astrophysics Data System (ADS)

Taranova, O. G.; Tatarnikov, A. M.; Shenavrin, V. I.; Tatarnikova, A. A.

2014-02-01

The results of JHKLM photometry for Nova Delphini 2013 obtained in the first sixty days after its outburst are analyzed. Analysis of the energy distribution in a wide spectral range (0.36-5 µm) has shown that the source mimics the emission of normal supergiants of spectral types B5 and A0 for two dates near its optical brightness maximum, August 15.94 UT and August 16.86 UT, respectively. The distance to the nova has been estimated to be D ≈ 3 kpc. For these dates, the following parameters have been estimated: the source's bolometric fluxes ˜9 × 10-7 and ˜7.2 × 10-7 erg s-1 cm-2, luminosities L ≈ 2.5 × 105 L ⊙ and ≈2 × 105 L ⊙, and radii R ≈ 6.3 × 1012 and ≈1.2 × 1013 cm. The nova's expansion velocity near its optical brightness maximum was ˜700 km s-1. An infrared (IR) excess associated with the formation of a dust shell is shown to have appeared in the energy distribution one month after the optical brightness maximum. The parameters of the dust component have been estimated for two dates of observations, JD2456557.28 (September 21, 2013) and JD2456577.18 (October 11, 2013). For these dates, the dust shell parameters have been estimated: the color temperatures ≈1500 and ≈1200 K, radii ≈6.5 × 1013 and 1.7 × 1014 cm, luminosities ˜4 × 103 L ⊙ and ˜1.1 × 104 L ⊙, and the dust mass ˜1.6 × 1024 and ˜1025 g. The total mass of the material ejected in twenty days (gas + dust) could reach ˜1.1 × 10-6 M ⊙. The rate of dust supply to the nova shell was ˜8 × 10-8 M ⊙ yr-1. The expansion velocity of the dust shell was about 600 km s-1.

Models for various aspects of dwarf novae and nova-like stars

NASA Technical Reports Server (NTRS)

Ladous, Constanze

1993-01-01

The first attempts to explain the nature of dwarf novae were based on the assumption of single-star phenomena, in which emission lines were assumed to be caused by circumstellar gas shells. The outburst behavior was tentatively ascribed to the kind of (also not understood) mechanism leading to nova outbursts. The realization that some, and possibly all, dwarf novae and nova-like stars (and novae) are binaries eventually led to models which bore more and more similarities to the modern interpretation on the basis of the Roche model. Not all cataclysmic variables are known binaries. In fact, with respect to the entire number of known objects, the proven binaries are still the minority, but all the brightest variables are in fact known to binaries. Not a single system is known which exhibits the usual characteristics of a cataclysmic variable and at the same time can be declared with certainty to be a single star. Two systems are known, the dwarf nova EY Cyg and the recurrent nova V1017 Sgr, in which, in spite of intensive search, no radial velocity variations have been found; but they still exhibit composite spectra consisting of a bright continuum, an emission spectrum, and a cool absorption spectrum. If the Roche model is correct, it is to be expected that a small percentage of objects is viewed pole-on, so orbital motions do not make themselves felt as Doppler shifts of spectral lines. So even these two systems support the hypothesis that all cataclysmic variables (with the possible exception of symbiotic stars) are binaries. In cataclysmic variables, it seems that the brightness changes observed in dwarf novae and nova-like stars in the optical and the UV are due directly to changes in the accretion disks. The study and understanding of accretion disks in these systems can bear potentially valuable consequences for many other fields in astronomy. The observed spectra of dwarf novae and nova-like stars comprise a fairly large range: pure emission spectra, pure absorption spectra, a mixture of both, asymmetric line profiles, very different slopes of the continuous flux distribution -- and one single system may exhibit all of these features at different times. Agreement and disagreement between computed and observed spectra should show whether or not the Roche model is applicable and where it probably will have to be modified and improved. Except for their outburst behavior and its immediate consequences, novae, dwarf novae, and nova-like stars cannot be physically distinguished from each other.

The Expanding Bipolar Shell of the Helium Nova V445 Puppis

NASA Astrophysics Data System (ADS)

Woudt, P. A.; Steeghs, D.; Karovska, M.; Warner, B.; Groot, P. J.; Nelemans, G.; Roelofs, G. H. A.; Marsh, T. R.; Nagayama, T.; Smits, D. P.; O'Brien, T.

2009-11-01

From multi-epoch adaptive optics imaging and integral field unit spectroscopy, we report the discovery of an expanding and narrowly confined bipolar shell surrounding the helium nova V445 Puppis (Nova Puppis 2000). An equatorial dust disc obscures the nova remnant, and the outflow is characterized by a large polar outflow velocity of 6720 ± 650 km s-1 and knots moving at even larger velocities of 8450 ± 570 km s-1. We derive an expansion parallax distance of 8.2 ± 0.5 kpc and deduce a pre-outburst luminosity of the underlying binary of log L/L sun = 4.34 ± 0.36. The derived luminosity suggests that V445 Puppis probably contains a massive white dwarf accreting at high rate from a helium star companion making it part of a population of binary stars that potentially lead to supernova Ia explosions due to accumulation of helium-rich material on the surface of a massive white dwarf.

Synthetic Spectral Ananlysis of the Nova-Like Variable KQ Mon

NASA Astrophysics Data System (ADS)

Wolfe, Aaron; Sion, E.

2011-01-01

KQ Mon is classified as a nova-like variable with an uncertain orbital period of 0.128 d. Optical spectra (Zwitter, T. & Munari, U.1994, A&AS, 107, 503) reveal no emission lines but strong Balmer absorption features. High speed flickering has been observed indicative of accretion. IUE spectra reveal deep absorption lines due to C III, C II, Si III, Si IV, C IV, He II but no P Cygni profiles indicative of outflow. Its classification in Ritter and Kolb (2006) as a UX UMa type nova-like is uncertain. We have carried out the first synthetic spectral analysis of the IUE archival spectra of KQ Mon with realistic accretion disk models with vertical structure and high gravity photosphere models. The results of our model atmosphere and model accretion disk analyses are presented. We discuss the properties that we have derived for KQ Mon and compare KQ Mon with other nova-like variables viewed at low inclination. This work was supported in part by NSF grant AST0807892 to Villanova University.

Voices from the Swamp: Identifying the Professional Development Needs of Principals.

ERIC Educational Resources Information Center

Goddard, J. Tim

During the mid- to late-1990s, economic downturns, outmigration of residents, and school closures in Nova Scotia contributed to a lack of movement among school administrators and thus a bottleneck of candidates seeking promotion to the principalship. This paper presents findings of a study that identified the professional-development needs of…

Damage resistant optics for a mega-joule solid-state laser

NASA Astrophysics Data System (ADS)

Campbell, J. H.; Rainer, F.; Kozlowski, M. R.; Wolfe, C. R.; Thomas, I.; Milanovich, F.

1990-12-01

Research on Inertial Confinement Fusion (ICF) has progressed rapidly in the past several years. As a consequence, LLNL is developing plans to upgrade the current 120 kJ solid state (Nd3+ phosphate glass) Nova laser to a 1.5 to 2 megajoule system with the goal of achieving fusion ignition. The design of the planned Nova Upgrade is briefly discussed. Because of recent improvements in the damage resistance of optical materials it is now technically and economically feasible to build a megajoule-class solid state laser. Specifically, the damage threshold of Nd(+3)-doped phosphate laser glass, multilayer dielectric coatings, and non-linear optical crystals (e.g., KDP) have been dramatically improved. These materials now meet the fluence requirements for a 1.5 to 2 MJ Nd(+3)-glass laser operating at 1054 and 351 nm and at a pulse length of 3 ns. The recent improvements in damage thresholds are reviewed; threshold data at both 1064 and 355 nm and the measured pulse length scaling are presented.

Damage resistant optics for a megajoule solid state laser

NASA Astrophysics Data System (ADS)

Campbell, Jack H.; Rainer, Frank; Kozlowski, Mark R.; Wolfe, C. Robert; Thomas, Ian M.; Milanovich, Fred P.

1991-06-01

Research on Inertial Confinement Fusion (ICF) has progressed rapidly in the past several years. As a consequence LLNL is developing plans to upgrade the current 120 kJ solid state (Nd3-phosphate glass) Nova laser to a 1 . 5 to 2 megajoule system with the goal of achieving fusion ignition. The design of the planned Nova Upgrade is briefly discussed. Because of recent improvements in the damage resistance of optical materials it is now technically and economically feasible to build a megajoule-class solid state laser. Specifically the damage threshold of Nd3- doped phosphate laser glass muliilayer dielectric coatings and non-linear optical crystals (e. g. KDP) have been dramatically improved. These materials now meet the fluence requirements for a 1. 5-2 MJ Nd3-glass laser operating at 1054 and 351 nm and at a pulse length of 3 ns. The recent improvements in damage thresholds are reviewed threshold data at both 1064 and 355 nm and the measured pulse length scaling are presented. 1.

Composite polymer: Glass edge cladding for laser disks

DOEpatents

Powell, H.T.; Wolfe, C.A.; Campbell, J.H.; Murray, J.E.; Riley, M.O.; Lyon, R.E.; Jessop, E.S.

1987-11-02

Large neodymium glass laser disks for disk amplifiers such as those used in the Nova laser require an edge cladding which absorbs at 1 micrometer. This cladding prevents edge reflections from causing parasitic oscillations which would otherwise deplete the gain. Nova now utilizes volume-absorbing monolithic-glass claddings which are fused at high temperature to the disks. These perform quite well but are expensive to produce. Absorbing glass strips are adhesively bonded to the edges of polygonal disks using a bonding agent whose index of refraction matches that of both the laser and absorbing glass. Optical finishing occurs after the strips are attached. Laser disks constructed with such claddings have shown identical gain performance to the previous Nova disks and have been tested for hundreds of shots without significant degradation. 18 figs.

Composite polymer-glass edge cladding for laser disks

DOEpatents

Powell, Howard T.; Riley, Michael O.; Wolfe, Charles R.; Lyon, Richard E.; Campbell, John H.; Jessop, Edward S.; Murray, James E.

1989-01-01

Large neodymium glass laser disks for disk amplifiers such as those used in the Nova laser require an edge cladding which absorbs at 1 micrometer. This cladding prevents edge reflections from causing parasitic oscillations which would otherwise deplete the gain. Nova now utilizes volume-absorbing monolithic-glass claddings which are fused at high temperature to the disks. These perform quite well but are expensive to produce. Absorbing glass strips are adhesively bonded to the edges of polygonal disks using a bonding agent whose index of refraction matches that of both the laser and absorbing glass. Optical finishing occurs after the strips are attached. Laser disks constructed with such claddings have shown identical gain performance to the previous Nova disks and have been tested for hundreds of shots without significant degradation.

An Accreting White Dwarf near the Chandrasekhar Limit in the Andromeda Galaxy

NASA Technical Reports Server (NTRS)

Tang, Sumin; Bildsten, Lars; Wolf, William M.; Li, K. L.; Kong, Albert K. H.; Cao, Yi; Cenko, S. Bradley; De Cia, Annalisa; Kasliwal, Mansi M.; Kulkarni, Shrinivas R.;

OISTER optical and near-infrared observations of the super-Chandrasekhar supernova candidate SN 2012dn: Dust emission from the circumstellar shell

NASA Astrophysics Data System (ADS)

Yamanaka, Masayuki; Maeda, Keiichi; Tanaka, Masaomi; Tominaga, Nozomu; Kawabata, Koji S.; Takaki, Katsutoshi; Kawabata, Miho; Nakaoka, Tatsuya; Ueno, Issei; Akitaya, Hiroshi; Nagayama, Takahiro; Takahashi, Jun; Honda, Satoshi; Omodaka, Toshihiro; Miyanoshita, Ryo; Nagao, Takashi; Watanabe, Makoto; Isogai, Mizuki; Arai, Akira; Itoh, Ryosuke; Ui, Takahiro; Uemura, Makoto; Yoshida, Michitoshi; Hanayama, Hidekazu; Kuroda, Daisuke; Ukita, Nobuharu; Yanagisawa, Kenshi; Izumiura, Hideyuki; Saito, Yoshihiko; Masumoto, Kazunari; Ono, Rikako; Noguchi, Ryo; Matsumoto, Katsura; Nogami, Daisaku; Morokuma, Tomoki; Oasa, Yumiko; Sekiguchi, Kazuhiro

2016-10-01

We present extensively dense observations of the super-Chandrasekhar supernova (SC SN) candidate SN 2012dn from -11 to +140 d after the date of its B-band maximum in the optical and near-infrared (NIR) wavelengths conducted through the OISTER ToO (Optical and Infrared Synergetic Telescopes for Education and Research Target of Opportunity) program. The NIR light curves and color evolutions up to 35 days after the B-band maximum provided an excellent match with those of another SC SN 2009dc, providing further support to the nature of SN 2012dn as an SC SN. We found that SN 2012dn exhibited strong excesses in the NIR wavelengths from 30 d after the B-band maximum. The H- and Ks-band light curves exhibited much later maximum dates at 40 and 70 d after the B-band maximum, respectively, compared with those of normal SNe Ia. The H- and Ks-band light curves subtracted by those of SN 2009dc displayed plateaued evolutions, indicating an NIR echo from the surrounding dust. The distance to the inner boundary of the dust shell is limited to 4.8-6.4 × 10-2 pc. No emission lines were found in its early phase spectra, suggesting that the ejecta-circumstellar material interaction could not occur. On the other hand, we found no signature that strongly supports the scenario of dust formation. The mass-loss rate of the pre-explosion system is estimated to be 10-6-10-5 M⊙ yr-1, assuming that the wind velocity of the system is 10-100 km s-1, which suggests that the progenitor of SN 2012dn could be a recurrent nova system. We conclude that the progenitor of this SC SN could be explained by the single-degenerate scenario.

The Massive CO White Dwarf in the Symbiotic Recurrent Nova RS Ophiuchi

NASA Astrophysics Data System (ADS)

Mikołajewska, Joanna; Shara, Michael M.

2017-10-01

If accreting white dwarfs (WDs) in binary systems are to produce type Ia supernovae (SNe Ia), they must grow to nearly the Chandrasekhar mass and ignite carbon burning. Proving conclusively that a WD has grown substantially since its birth is a challenging task. Slow accretion of hydrogen inevitably leads to the erosion, rather than the growth of WDs. Rapid hydrogen accretion does lead to growth of a helium layer, due to both decreased degeneracy and the inhibition of mixing of the accreted hydrogen with the underlying WD. However, until recently, simulations of helium-accreting WDs all claimed to show the explosive ejection of a helium envelope once it exceeded ˜ {10}-1 {M}⊙ . Because CO WDs cannot be born with masses in excess of ˜ 1.1 {M}⊙ , any such object in excess of ˜ 1.2 {M}⊙ must have grown substantially. We demonstrate that the WD in the symbiotic nova RS Oph is in the mass range 1.2-1.4 M ⊙. We compare UV spectra of RS Oph with those of novae with ONe WDs and with novae erupting on CO WDs. The RS Oph WD is clearly made of CO, demonstrating that it has grown substantially since birth. It is a prime candidate to eventually produce an SN Ia.

Light-curve Analysis of Neon Novae

NASA Astrophysics Data System (ADS)

Hachisu, Izumi; Kato, Mariko

2016-01-01

We analyzed light curves of five neon novae, QU Vul, V351 Pup, V382 Vel, V693 CrA, and V1974 Cyg, and determined their white dwarf (WD) masses and distance moduli on the basis of theoretical light curves composed of free-free and photospheric emission. For QU Vul, we obtained a distance of d ˜ 2.4 kpc, reddening of E(B - V) ˜ 0.55, and WD mass of MWD = 0.82-0.96 {M}⊙ . This suggests that an oxygen-neon WD lost a mass of more than ˜ 0.1 {M}⊙ since its birth. For V351 Pup, we obtained d˜ 5.5 {{kpc}}, E(B-V)˜ 0.45, and {M}{{WD}}=0.98-1.1 {M}⊙ . For V382 Vel, we obtained d˜ 1.6 {{kpc}}, E(B-V)˜ 0.15, and {M}{{WD}}=1.13-1.28 {M}⊙ . For V693 CrA, we obtained d˜ 7.1 {{kpc}}, E(B-V)˜ 0.05, and {M}{{WD}}=1.15-1.25 {M}⊙ . For V1974 Cyg, we obtained d˜ 1.8 {{kpc}}, E(B-V)˜ 0.30, and {M}{{WD}}=0.95-1.1 {M}⊙ . For comparison, we added the carbon-oxygen nova V1668 Cyg to our analysis and obtained d˜ 5.4 {{kpc}}, E(B-V)˜ 0.30, and {M}{{WD}}=0.98-1.1 {M}⊙ . In QU Vul, photospheric emission contributes 0.4-0.8 mag at most to the optical light curve compared with free-free emission only. In V351 Pup and V1974 Cyg, photospheric emission contributes very little (0.2-0.4 mag at most) to the optical light curve. In V382 Vel and V693 CrA, free-free emission dominates the continuum spectra, and photospheric emission does not contribute to the optical magnitudes. We also discuss the maximum magnitude versus rate of decline relation for these novae based on the universal decline law.

Far-ultraviolet Spectroscopy of the Nova-like Variable KQ Monocerotis: A New SW Sextantis Star?

NASA Astrophysics Data System (ADS)

Wolfe, Aaron; Sion, Edward M.; Bond, Howard E.

2013-06-01

New optical spectra obtained with the SMARTS 1.5 m telescope and archival International Ultraviolet Explorer (IUE) far-ultraviolet (FUV) spectra of the nova-like variable KQ Mon are discussed. The optical spectra reveal Balmer lines in absorption as well as He I absorption superposed on a blue continuum. The 2011 optical spectrum is similar to the KPNO 2.1 m IIDS spectrum we obtained 33 years earlier except that the Balmer and He I absorption is stronger in 2011. Far-ultraviolet IUE spectra reveal deep absorption lines due to C II, Si III, Si IV, C IV, and He II, but no P Cygni profiles indicative of wind outflow. We present the results of the first synthetic spectral analysis of the IUE archival spectra of KQ Mon with realistic optically thick, steady-state, viscous accretion-disk models with vertical structure and high-gravity photosphere models. We find that the photosphere of the white dwarf (WD) contributes very little FUV flux to the spectrum and is overwhelmed by the accretion light of a steady disk. Disk models corresponding to a WD mass of ~0.6 M ⊙, with an accretion rate of order 10-9 M ⊙ yr-1 and disk inclinations between 60° and 75°, yield distances from the normalization in the range of 144-165 pc. KQ Mon is discussed with respect to other nova-like variables. Its spectroscopic similarity to the FUV spectra of three definite SW Sex stars suggests that it is likely a member of the SW Sex class and lends support to the possibility that the WD is magnetic.

Discovery of Seven ASAS-SN Candidate Supernovae

NASA Astrophysics Data System (ADS)

Brimacombe, J.; Stone, G.; Kiyota, S.; Vallely, P.; Stanek, K. Z.; Brown, J. S.; Kochanek, C. S.; Shields, J.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Nicholls, B.

2017-11-01

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, the quadruple 14-cm "Leavitt" telescope in Fort Davis, Texas, and the quadruple 14-cm "Cassius" and "Paczynski" telescopes in Cerro Tololo, Chile, we discovered several new transient sources.

Discovery of Seven ASAS-SN Supernova Candidates

NASA Astrophysics Data System (ADS)

Brimacombe, J.; Post, R. S.; Trappett, D.; Marples, P.; Koff, R. A.; Stone, G.; Vallely, P.; Stanek, K. Z.; Brown, J. S.; Kochanek, C. S.; Shields, J. V.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Kiyota, S.

2017-12-01

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, the quadruple 14-cm "Leavitt" telescope in Fort Davis, Texas, and the quadruple 14-cm "Cassius" and "Paczynski" telescopes in Cerro Tololo, Chile, we discovered several new transient sources.

A Self-consistent Model for a Full Cycle of Recurrent Novae—Wind Mass-loss Rate and X-Ray Luminosity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kato, Mariko; Saio, Hideyuki; Hachisu, Izumi, E-mail: mariko.kato@hc.st.keio.ac.jp

2017-04-01

An unexpectedly slow evolution in the pre-optical-maximum phase was suggested in the very short recurrence period of nova M31N 2008-12a. To obtain reasonable nova light curves we have improved our calculation method by consistently combining optically thick wind solutions of hydrogen-rich envelopes with white dwarf (WD) structures calculated by a Henyey-type evolution code. The wind mass-loss rate is properly determined with high accuracy. We have calculated light curve models for 1.2 M {sub ⊙} and 1.38 M {sub ⊙} WDs with mass accretion rates corresponding to recurrence periods of 10 yr and 1 yr, respectively. The outburst lasts 590/29 days,more » in which the pre-optical-maximum phase is 82/16 days, for 1.2/1.38 M {sub ⊙}, respectively. Optically thick winds start at the end of the X-ray flash and cease at the beginning of the supersoft X-ray phase. We also present supersoft X-ray light curves including a prompt X-ray flash and later supersoft X-ray phase.« less

NR TrA (Nova TrA 2008) monitoring in support of XMM observations

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-03-01

Dr. Fred Walter (Stony Brook University) has requested AAVSO observers' assistance in monitoring NR TrA (Nova TrA 2008) in support of upcoming XMM Newton observations. The XMM observations will take place 2017 March 13 06:21 through March 14 10:34 UT. Walter writes: "NR TrA (Nova TrA 2008) is a compact eclipsing system with a 5.5 hour period. It was a normal Fe II nova that, upon reaching quiescence, took on the appearance of a super-soft source in the optical high state, which suggests an extremely high mass accretion rate. The optical spectrum is dominated by hot permitted lines of O VI, N V, C IV, and He II. Some nova-like variables have similar spectra, though generally without the hot emission lines. Primary eclipse is broad - nearly 40% of the orbit - and deeper at shorter wavelengths, which suggests the eclipse of a hot accretion disk. Primary eclipse depth is about 1 mag at V. There appears to be a shallow secondary eclipse.The primary aim [of the XMM observations] is to detect and characterize the eclipse at X-ray and UV wavelengths. We will obtain low cadence BVRI/JHK observations with SMARTS/Andicam. We request AAVSO support to obtain continuous photometric time series simultaneous with the XMM observation. Any filters are acceptable, but standard Johnson B, V or Cousins R, I are preferred. Clear filters are acceptable. Time resolution better than 5 minutes and uncertainties (outside of eclipse) <0.02 mag are preferred. The best ephemeris I have is: minimum light at JD 55956.822 + 0.219109E. This is based on data from 2013-2015." Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

NuMI Flux Predictions for NOvA and MINERvA

NASA Astrophysics Data System (ADS)

Aliaga Soplin, Leonidas; Nova Collaboration; Minerva Collaboration

2017-01-01

The determination of the neutrino flux in any conventional neutrino beam presents a challenge for the current and future short and long baseline neutrino experiments. The uncertainties associated with the production and attenuation of the hadrons in the beamline materials along with those associated with the beam optics have a big effect in the knowledge of the flux. For experiments like MINERvA and NOvA, understanding the flux is crucial since it enters directly into every neutrino-nucleus cross-section measurement. The majority of this work involves predicting the neutrino flux using dedicated hadron production measurements from hadron-nucleus collisions. The predictions at the MINERvA and NOvA near detectors are presented as well as the results of incorporating in-situ MINERvA data that can provide additional constraints. These results have been fully implemented in MINERvA and they are currently use for its cross-section analysis. The implementation for NoVA is underway. The procedure and conclusions of this work will have a big impact on future hadron production experiments and on determining the flux for the upcoming DUNE experiment.

Nova Eruptions from Radio to Gamma-raysówith AAVSO Data in the Middle (Abstract)

NASA Astrophysics Data System (ADS)

Mukai, K.; Kafka, S.; Chomiuk, L.; Li, R.; Finzell, T.; Linford, J.; Sokoloski, J.; Nelson, T.; Rupen, M.; Mioduszewski, A.; Weston, J.

2018-06-01

(Abstract only) Novae are among the longest-known class of optical transients. In recent years, V1369 Cen in the south reached magnitude 3.3 in late 2013, and had repeated (but not periodic) cycles of re-brightening. Earlier in 2013, V339 Del almost reached magnitude 4.0 during the northern summer. An expanding ball of gas, at about 10,000 K, expelled by a nuclear explosion on the surface of a white dwarf, can explain much of the visible light outputs of novae. But these spectacular visible light displays turn out to be just a small part of the show. Novae are also transient objects in the radio through gamma-raysóin addition to the warm, visible light-emitting gas, we need cold dust particles that emit in the infra-red, 10 million degree shock-heated gas that emits hard X-rays, and the exposed surface of the nuclear-burning white dwarf that emits soft X-rays. Last but not least, we need an exotic process of particle acceleration to explain the gamma-rays and some radio data.

Suzaku Observation of the Classical Nova V2491 Cyg in Quiescence

NASA Technical Reports Server (NTRS)

Zemko, P.; Mukai, K.; Orio, M.

2015-01-01

We present Suzaku XIS observation of V2491 Cyg (Nova Cyg 2008 No. 2) obtained in quiescence, more than two years after the outburst. The nova was detected as a very luminous source in a wide spectral range from soft to hard X-rays. A very soft blackbody-like component peaking at 0.5 keV indicates that either we observe remaining, localized hydrogen burning on the surface of the white dwarf, or accretion onto a magnetized polar cap. In the second case, V2491 Cyg is a candidate "soft intermediate polar". We obtained the best fit for the X-ray spectra with several components: two of thermal plasma, a blackbody and a complex absorber. The later is typical of intermediate polars. The X-ray light-curve shows a modulation with an approximately 38 min period. The amplitude of this modulation is strongly energy dependent and reaches maximum in the 0.8-2.0 keV range. We discuss the origin of the X-ray emission and pulsations, and the likelihood of the intermediate polar scenario.

High-speed photometry of the eclipsing dwarf nova OY Carinae

NASA Technical Reports Server (NTRS)

Cook, M. C.

1985-01-01

High-speed photometry of the eclipsing dwarf nova OY Car in the quiescent state is presented. OY Car becomes highly reddened during eclipse, with minimum flux colours inconsistent with optically thick emission in the U and B bandpasses. Mass ratios in the range 6.5 to 12 are required to reconcile the eclipse structure with theoretical gas stream trajectories. Primary eclipse timings reveal a significant decrease in the orbital period and the duration of primary eclipse indicates the presence of a luminous ring about the white dwarf. The hotspot eclipse reveals a hotspot which is elongated along the rim of the accretion disc, with optical emission being non-uniformly distributed along the rim. The location of the hotspot in the accretion disc implies a disc radius larger than that of an inviscid disc, with variation in the position of the hotspot being consistent with a fixed stream trajectory.

Analysis of observations of the dwarf nova pegasi 2010

NASA Astrophysics Data System (ADS)

Shimansky, V. V.; Mitrofanova, A. A.; Borisov, N. V.; Gabdeev, M. M.

2013-06-01

Analysis of photometric and spectroscopic observations of GSC 02197-00886 at the outburst maximum (on May 8, 2010) and at the stage of relaxation towards the quiescent (on August 4, 2010) was performed. Radiation of an optically thick accretion disc with a hot boundary layer dominates the spectra, which are consistent with the spectra of a WZ Sge-type dwarf novae. In the relaxation phase, an optically thin accretion disc with radiation in the HI and HeI emission lines is observed against the background of the absorption spectrum of a white dwarf. The parameters of GSC 02197-00886, which were determined by combining the radial velocities of the components with the assumption that the secondary component is close to mainsequence stars, differ significantly from the parameters that characterize other WZ Sge-type systems. We hypothesize that the secondary component was excited in the course of the outburst and experienced long-lasting relaxation towards the main-sequence state.

Photoionisation modelling of Nova LMC 1990 #1

NASA Technical Reports Server (NTRS)

Dopita, M. A.; Meatheringham, S. J.; Sutherland, R.; Williams, R. E.; Starrfield, S.; Sonneborn, G.; Shore, S.

1992-01-01

Nova LMC 1990A was a very fast Ne-O-Mg nova, for which a particularly dense coverage of spectral observation in both the UV and optical was obtained. The data for the nebular phase were subjected to an analysis by the photoionization modeling code MAPPINGS 2. The following parameters were obtained: L(sub max) = 8 x 10(exp 4) solar luminosity, T(sub eff) = 2 x 10(exp 5) K and the mass of ejecta = 5/5 x 10(exp -5) solar mass. The abundnace ratios in the ejecta were similar to those obtained by Williams et al. (1985) in the case of V693 CrA 1981. The N/O ratio and the overabundance of Al is consistent with ourburst on a ONeMg white dwarf of mass approximately equal to 1.2 solar mass, but the super-Eddington luminosity, and amount of mass ejected presents some problems to theory.

Nova V2362 Cygni (Nova Cygni 2006): Spitzer, Swift, and Ground-Based Spectral Evolution

NASA Technical Reports Server (NTRS)

Lynch, David K.; Venturini, Catherine C.; Mazuk, S.; Woodward, Charles; Gehrz, Robert; Rayner, John; Helton, L.A.; Ness, Jan-Uwe; Starrfield, Sumner; Rudy, Richard J.;

FROM X-RAY DIPS TO ECLIPSE: WITNESSING DISK REFORMATION IN THE RECURRENT NOVA U Sco

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ness, J.-U.; Talavera, A.; Gonzalez-Riestra, R.

2012-01-20

The tenth recorded outburst of the recurrent eclipsing nova U Sco was observed simultaneously in X-ray, UV, and optical by XMM-Newton on days 22.9 and 34.9 after the outburst. Two full passages of the companion in front of the nova ejecta were observed, as was the reformation of the accretion disk. On day 22.9, we observed smooth eclipses in UV and optical but deep dips in the X-ray light curve that disappeared by day 34.9, yielding clean eclipses in all bands. X-ray dips can be caused by clumpy absorbing material that intersects the line of sight while moving along highlymore » elliptical trajectories. Cold material from the companion could explain the absence of dips in UV and optical light. The disappearance of X-ray dips before day 34.9 implies significant progress in the formation of the disk. The X-ray spectra contain photospheric continuum emission plus strong emission lines, but no clear absorption lines. Both continuum and emission lines in the X-ray spectra indicate a temperature increase from day 22.9 to day 34.9. We find clear evidence in the spectra and light curves for Thompson scattering of the photospheric emission from the white dwarf. Photospheric absorption lines can be smeared out during scattering in a plasma of fast electrons. We also find spectral signatures of resonant line scattering that lead to the observation of the strong emission lines. Their dominance could be a general phenomenon in high-inclination systems such as Cal 87.« less

Inertial Confinement Fusion Annual Report 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kauffman, Robert L.

The ICF Program has undergone a significant change in 1999 with the decommissioning of the Nova laser and the transfer of much of the experimental program to the OMEGA laser at the University of Rochester. The Nova laser ended operations with the final experiment conducted on May 27, 1999. This marked the end to one of DOE's most successful experimental facilities. Since its commissioning in 1985, Nova performed 13,424 experiments supporting ICF, Defense Sciences, high-power laser research, and basic science research. At the time of its commissioning, Nova was the world's most powerful laser. Its early experiments demonstrated that 3ωmore » light could produce high-drive, low-preheat environment required for indirect-drive ICE. In the early 1990s, the technical program on Nova for indirect drive ignition was defined by the Nova technical contract established by National Academy Review of ICF in 1990. Successful completion of this research program contributed significantly to the recommendation by the ICF Advisory Committee in 1995 to proceed with the construction of the National Ignition Facility? Nova experiments also demonstrated the utility of high-powered lasers for studying the physics of interest to Defense Sciences. Now, high-powered lasers along with pulsed-power machines are the principal facilities for studying high energy density science in DOE's Stockpile Stewardship Program (SSP). In 1997, one beam of Nova was converted to a short pulsed beam producing a petawatt of power in subpicosecond pulses. The petawatt beam was used for pioneering research in short-pulse laser-matter interactions relevant to fast ignitor ICF and short pulsed x-ray, electron, and particle production for use as probes. Nova is being disassembled and the space is being used to support NIF construction. Nova components are being distributed to a number of other laser laboratories around the world for reuse as determined by DOE. This report summarizes the research performed by the ICF Program in FY1999. The report is divided into five sections corresponding to the major areas of program activities. These are sections on (1) ignition target physics experiments theory and modeling, (2) high energy density experimental science, (3) target development, fabrication, and handling, (4) NIF laser development, and (5) optics technology development.« less

Modelling the structure and kinematics of the Firework nebula: The nature of the GK Persei nova shell and its jet-like feature

NASA Astrophysics Data System (ADS)

Harvey, E.; Redman, M. P.; Boumis, P.; Akras, S.

2016-10-01

Aims: The shaping mechanisms of old nova remnants are probes for several important and unexplained processes, such as dust formation and the structure of evolved star nebulae. To gain a more complete understanding of the dynamics of the GK Per (1901) remnant, an examination of symmetry of the nova shell is explored, followed by a kinematical analysis of the previously detected jet-like feature in the context of the surrounding fossil planetary nebula. Methods: Faint-object high-resolution echelle spectroscopic observations and imaging were undertaken covering the knots which comprise the nova shell and the surrounding nebulosity. New imaging from the Aristarchos telescope in Greece and long-slit spectra from the Manchester Echelle Spectrometer instrument at the San Pedro Mártir observatory in Mexico were obtained, supplemented with archival observations from several other optical telescopes. Position-velocity arrays are produced of the shell, and also individual knots, and are then used for morpho-kinematic modelling with the shape code. The overall structure of the old knotty nova shell of GK Per and the planetary nebula in which it is embedded is then analysed. Results: Evidence is found for the interaction of knots with each other and with a wind component, most likely the periodic fast wind emanating from the central binary system. We find that a cylindrical shell with a lower velocity polar structure gives the best model fit to the spectroscopy and imaging. We show in this work that the previously seen jet-like feature is of low velocity. Conclusions: The individual knots have irregular tail shapes; we propose here that they emanate from episodic winds from ongoing dwarf nova outbursts by the central system. The nova shell is cylindrical, not spherical, and the symmetry axis relates to the inclination of the central binary system. Furthermore, the cylinder axis is aligned with the long axis of the bipolar planetary nebula in which it is embedded. Thus, the central binary system is responsible for the bipolarity of the planetary nebula and the cylindrical nova shell. The gradual planetary nebula ejecta versus sudden nova ejecta is the reason for the different degrees of bipolarity. We propose that the "jet" feature is an illuminated lobe of the fossil planetary nebula that surrounds the nova shell.

Searching for Black Holes

NASA Technical Reports Server (NTRS)

Garcia, M.

1998-01-01

Our UV/VIS work concentrates on black hole X-ray nova. These objects consist of two stars in close orbit, one of which we believe is a black hole - our goal is to SHOW that one is a black hole. In order to reach this goal we carry out observations in the Optical, UV, IR and X-ray bands, and compare the observations to theoretical models. In the past year, our UV/VIS grant has provided partial support (mainly travel funds and page charges) for work we have done on X-ray nova containing black holes and neutron stars. We have been very successful in obtaining telescope time to support our project - we have completed approximately a dozen separate observing runs averaging 3 days each, using the MMT (5M), Lick 3M, KPNO 2.1M, CTIO 4M, CTIO 1.5M, and the SAO/WO 1.2M telescopes. These observations have allowed the identification of one new black hole (Nova Oph 1977), and allowed the mass of another to be measured (GS2000+25). Perhaps our most exciting new result is the evidence we have gathered for the existence of 'event horizons' in black hole X-ray nova.

Discovery of Six ASAS-SN Supernova Candidates

NASA Astrophysics Data System (ADS)

Brimacombe, J.; Stone, G.; Vallely, P.; Stanek, K. Z.; Brown, J. S.; Kochanek, C. S.; Shields, J.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Conseil, E.

2018-01-01

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, the quadruple 14-cm "Leavitt" telescope in Fort Davis, Texas, the quadruple 14-cm "Payne-Gaposchkin" telescope in Sutherland, South Africa, and the quadruple 14-cm "Cassius" and "Paczynski" telescopes in Cerro Tololo, Chile, we discovered several new transient sources.

Star of Bethlehem

NASA Astrophysics Data System (ADS)

Hughes, D.; Murdin, P.

2001-07-01

The biblical Star of Bethlehem, which heralded the birth of Jesus Christ, is only mentioned in the Gospel of St Matthew 2. The astrologically significant 7 bc triple conjunction of Jupiter and Saturn in the constellation of Pisces is the most likely candidate, although a comet/nova in 5 bc and a comet in 4 bc cannot be ruled out. There is also the possibility that the star was simply fictitious....

Two More Candidate AM Canum Venaticorum (am CVn) Binaries from the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Anderson, Scott F.; Becker, Andrew C.; Haggard, Daryl; Prieto, Jose Luis; Knapp, Gillian R.; Sako, Masao; Halford, Kelly E.; Jha, Saurabh; Martin, Blake; Holtzman, Jon; Frieman, Joshua A.; Garnavich, Peter M.; Hayward, Suzanne; Ivezić, Željko; Mukadam, Anjum S.; Sesar, Branimir; Szkody, Paula; Malanushenko, Viktor; Richmond, Michael W.; Schneider, Donald P.; York, Donald G.

2008-06-01

AM CVn systems are a select group of ultracompact binaries with the shortest orbital periods of any known binary subclass; mass transfer is likely from a low-mass (partially-)degenerate secondary onto a white dwarf primary, driven by gravitational radiation. In the past few years, the Sloan Digital Sky Survey (SDSS) has provided five new AM CVns. Here we report on two further candidates selected from more recent SDSS data. SDSS J1208+3550 is similar to the earlier SDSS discoveries, recognized as an AM CVn via its distinctive spectrum which is dominated by helium emission. From the expanded SDSS Data Release 6 (DR6) spectroscopic area, we provide an updated surface density estimate for such AM CVns of order 10-3.1-10-2.5 deg-2 for 15 < g < 20.5. In addition, we present another new candidate AM CVn, SDSS J2047+0008, which was discovered in the course of follow-up of SDSS-II supernova candidates. It shows nova-like outbursts in multi-epoch imaging data; in contrast to the other SDSS AM CVn discoveries, its (outburst) spectrum is dominated by helium absorption lines, reminiscent of KL Dra, and 2003aw. The variability selection of SDSS J2047+0008 from the 300 deg2 of SDSS Stripe 82 presages further AM CVn discoveries in future deep, multicolor, and time-domain surveys such as the Large Synoptic Survey Telescope (LSST). The new additions bring the total SDSS yield to seven AM CVns thus far, a substantial contribution to this rare subclass, versus the dozen previously known. Includes optical observations obtained with the Sloan Digital Sky Survey I and II and the Apache Point Observatory (APO) 3.5 m telescope which is owned and operated by the Astrophysical Research Consortium (ARC), and the WIYN Observatory which is a joint facility of the University of Wisconsin, Indiana University, Yale University, and NOAO.

Dust around the Cool Component of D-Type Symbiotic Binaries

NASA Astrophysics Data System (ADS)

Jurkic, Tomislav; Kotnik-Karuza, Dubravka

2018-04-01

D type symbiotic binaries are an excellent astrophysical laboratory for investigation of the dust properties and dust formation under the influence of theMira stellar wind and nova activity and of the mass loss and mass transfer between components in such a widely separated system. We present a study of the properties of circumstellar dust in symbiotic Miras by use of long-term near-IR photometry and colour indices. The published JHKL magnitudes of o Ceti, RX Pup, KM Vel, V366 Car, V835 Cen, RR Tel, HM Sge and R Aqr have been collected, analyzed and corrected for short-term variations caused by Mira pulsations. Assuming spherical temperature distribution of the dust in the close neighbourhood of the Mira, the DUSTY code was used to solve the radiative transfer in order to determine the dust temperature and its properties in each particular case. Common dust properties of the symbiotic Miras have been found, suggesting similar conditions in the condensation region of the studied symbiotic Miras. Silicate dust with the inner dust shell radius determined by the dust condensation and with the dust temperature of 900-1200 K can fully explain the observed colour indices. R Aqr is an exception and showed lower dust temperature of 650 K. Obscuration events visible in light curves can be explained by variable dust optical depth with minimal variations of other dust properties. More active symbioticMiras that underwent recent nova outbursts showed higher dust optical depths and larger maximum grain sizes of the order of μm, which means that the post-nova activity could stimulate the dust formation and the grain growth. Optically thicker dust shells and higher dust condensation temperatures have been found in symbiotic Miras compared to their single counterparts, suggesting different conditions for dust production.

Mapping wetlands in Nova Scotia with multi-beam RADARSAT-2 Polarimetric SAR, optical satellite imagery, and Lidar data

NASA Astrophysics Data System (ADS)

Jahncke, Raymond; Leblon, Brigitte; Bush, Peter; LaRocque, Armand

2018-06-01

Wetland maps currently in use by the Province of Nova Scotia, namely the Department of Natural Resources (DNR) wetland inventory map and the swamp wetland classes of the DNR forest map, need to be updated. In this study, wetlands were mapped in an area southwest of Halifax, Nova Scotia by classifying a combination of multi-date and multi-beam RADARSAT-2 C-band polarimetric SAR (polSAR) images with spring Lidar, and fall QuickBird optical data using the Random Forests (RF) classifier. The resulting map has five wetland classes (open-water/marsh complex, open bog, open fen, shrub/treed fen/bog, swamp), plus lakes and various upland classes. Its accuracy was assessed using data from 156 GPS wetland sites collected in 2012 and compared to the one obtained with the current wetland map of Nova Scotia. The best overall classification was obtained using a combination of Lidar, RADARSAT-2 HH, HV, VH, VV intensity with polarimetric variables, and QuickBird multispectral (89.2%). The classified image was compared to GPS validation sites to assess the mapping accuracy of the wetlands. It was first done considering a group consisting of all wetland classes including lakes. This showed that only 69.9% of the wetland sites were correctly identified when only the QuickBird classified image was used in the classification. With the addition of variables derived from lidar, the number of correctly identified wetlands increased to 88.5%. The accuracy remained the same with the addition of RADARSAT-2 (88.5%). When we tested the accuracy for identifying wetland classes (e.g. marsh complex vs. open bog) instead of grouped wetlands, the resulting wetland map performed best with either QuickBird and Lidar, or QuickBird, Lidar, and RADARSAT-2 (66%). The Province of Nova Scotia's current wetland inventory and its associated wetland classes (aerial-photo interpreted) were also assessed against the GPS wetland sites. This provincial inventory correctly identified 62.2% of the grouped wetlands and only 18.6% of the wetland classes. The current inventory's poor performance demonstrates the value of incorporating a combination of new data sources into the provincial wetland mapping.

Recent Results on SNRs and PWNe from the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Hays, Elizabeth

2010-01-01

Topics include: Fermi LAT Collaboration groups; galactic results from LAT; a GeV, wide-field instrument; the 1FGL catalog, the Fermi LAT 1FGL source catalog, unidentified gamma-ray sources; variability in 1FGL sources; curvature in 1FGL sources; spectral-variability classification; pulsars and their wind nebulae; gamma-ray pulsars and MSPs; GeV PWN search; Crab pulsar and nebula; Vela X nebular of Vela pulsar; MSH 15-52; supernova remnants, resolved GeV sources, galactic transients, LAT unassociated transient detections; gamma rays from a nova; V407 Cyngi - a symbiotic nova; V407 Cygni: a variable star; and March 11 - a nova. Summary slides include pulsars everywhere, blazars, LAT as an electron detector, cosmic ray spectrum, the Large Area Telescope, the Fermi Observatory, LAT sensitivity with time, candidate gamma-ray events, on-orbit energy calibration and rate, a 1 year sky map, LAT automated science processing, reported GeV flares, early activity and spectacular flare, gamma-ray transients near the galactic plane , two early unassociated transients, counter part search - Fermi J0910-5404; counterpart search 3EG J0903-3531, and a new LAT transient - J1057-6027.

Circumstellar dust in symbiotic novae

NASA Astrophysics Data System (ADS)

Jurkic, Tomislav; Kotnik-Karuza, Dubravka

2015-08-01

Physical properties of the circumstellar dust and associated physical mechanisms play an important role in understanding evolution of symbiotic binaries. We present a model of inner dust regions around the cool Mira component of the two symbiotic novae, RR Tel and HM Sge, based on the long-term near-IR photometry, infrared ISO spectra and mid-IR interferometry. Pulsation properties and long-term variabilities were found from the near-IR light curves. The dust properties were determined using the DUSTY code which solves the radiative transfer. No changes in pulsational parameters were found, but a long-term variations with periods of 20-25 years have been detected which cannot be attributed to orbital motion.Circumstellar silicate dust shell with inner dust shell temperatures between 900 K and 1300 K and of moderate optical depth can explain all the observations. RR Tel showed the presence of an optically thin CS dust envelope and an optically thick dust region outside the line of sight, which was further supported by the detailed modelling using the 2D LELUYA code. Obscuration events in RR Tel were explained by an increase in optical depth caused by the newly condensed dust leading to the formation of a compact dust shell. HM Sge showed permanent obscuration and a presence of a compact dust shell with a variable optical depth. Scattering of the near-IR colours can be understood by a change in sublimation temperature caused by the Mira variability. Presence of large dust grains (up to 4 µm) suggests an increased grain growth in conditions of increased mass loss. The mass loss rates of up to 17·10-6 MSun/yr were significantly higher than in intermediate-period single Miras and in agreement with longer-period O-rich AGB stars.Despite the nova outburst, HM Sge remained enshrouded in dust with no significant dust destruction. The existence of unperturbed dust shell suggests a small influence of the hot component and strong dust shielding from the UV flux. By the use of the CLOUDY code, we have showed that a high-density gas region can effectively stop most of the UV flux from the white dwarf and provide the observed dust shielding.

ASAS-SN Discovery of an Unprecedented >2 Magnitude Optical Flare from QSO B2 1420+32

NASA Astrophysics Data System (ADS)

Stanek, K. Z.; Kochanek, C. S.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Dong, Subo; Dai, X.

2017-12-01

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, and the quadruple 14-cm "Leavitt" telescope in Fort Davis, Texas, we have discovered an unprecedented, factor of 10 optical brightening of QSO B2 1420+32 (SDSS J142230.37+322310.4, z=0.68).

Photometric and Spectroscopic Analysis of Classical Novae: An Examination of Their Observational Characteristics and Greater Astronomical Impact

NASA Astrophysics Data System (ADS)

Helton, Lorren Andrew

2010-12-01

Classical novae (CNe) are violent thermonuclear explosions arising on the surface of white dwarfs in binary systems and are contributors to the chemical evolution of the interstellar medium through the production and ejection of copious amounts of metal-rich material. Observations and modeling of CNe eruptions illuminate numerous fundamental processes of astrophysical interest, including non-equilibrium thermonuclear runaway, radiative processes in dynamic nebular environments, binary star interaction, as well as dust condensation and grain growth. Here I summarize key findings from selected Galactic CNe observed as part of a 5 year, panchromatic optical/infrared observing campaign using Spitzer, Gemini, and other ground based optical facilities. In particular, I present detailed analysis of nova V1065 Centauri, including photoionization analysis of the emission lines, which enabled the derivation of abundances in the ejecta, and radiative transport modeling of the dust emission features, which allowed determination of the composition and characteristics of the dust in this system. I present analysis of three novae, V1974 Cygni, V382 Velorum, and V1494 Aquilae, observed from 4.4--15.5 years after outburst, discuss the characteristics of the nebulae at these late times, and estimate the abundances in their ejecta. In the case of V1494 Aql, I also report the first detection of neon. Finally, I present observations of three novae, DZ Crucis, V2361 Cygni, and V2362 Cygni, that exhibited unidentified infrared (UIR) features in their mid-infrared spectra, which exhibited unusual characteristics. I relate these features to other dusty novae in which features with similar characteristics were observed, and discuss possible sources for the UIR carriers. Analysis of the data obtained in the CNe monitoring campaign presented here highlights the need for synoptic observations obtained with broad wavelength coverage. Observations of V1065 Cen, which exhibited spectra rich in metals (e.g O, Ne, Mg, S, Ar, and Fe) produced during the thermonuclear runaway and through dredge up from the surface layers of the underlying WD, yielded robust estimates of WD composition, ejecta mass, and absolute abundances in the ejecta. Dusty novae such as V1065 Cen, V2362 Cyg, and V2361 Cyg, produced a variety of grain types as revealed by emission features characteristic of silicates, hydrogenated amorphous carbon dust, and PAH-like molecules, often in the same system. This data set is exceptional in that observations of many targets commenced immediately after eruption and followed the development for hundreds of days post-outburst providing unique insight into the evolution of conditions within the ejecta including the complete cycle of growth, processing, and dissipation of dust grains.

All-sky monitor observations of the decay of A0620-00 (Nova monocerotis 1975)

NASA Technical Reports Server (NTRS)

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

1976-01-01

The All-Sky X-ray Monitor onboard Ariel 5 has observed the 3-6 keV decline of the bright transient X-ray source A0620-00 on a virtually continuous basis during the period September 1975 - March 1976. The source behavior on timescales 100 minutes is characterized by smooth, exponential decays interrupted by substantial increases in October and February. The latter increase was an order-of-magnitude rise above the extrapolated exponential fall-off, and was followed by a final rapid decline. Upper limits of 2.5% and 10% were found for any periodicities in the range 0d.2 - 10d during the early and later decay phases, respectively. A probable correlation between the optical and 3-6 keV emission from A0620-00 was noted, effectively ruling out models involving traditional optical novae in favor of Roche-lobe overflow in a binary system. The existing data on the transient X-ray sources is consistent with two distinct luminosity-lifetime classes of these objects.

The X-Ray Evolution of the Symbiotic Star V 407 Cygni During Its 2010 Outburst

NASA Technical Reports Server (NTRS)

Mukai, K.; Nelson, T.; Chomiuk, L.; Donato, D.; Sokoloski, J.

2011-01-01

We present a summary of Swift and Suzaku X-ray observations of the 2010 nova outburst of the symbiotic star, V 407 Cyg. The Suzaku spectrum obtained on day 30 indicates the presence of the supersoft component from the white dwarf surface, as well as optically thin component from the shock between the nova ejecta and the Mira wind. The Swift observations then allow us to track the evolution of both components from day 4 to day 150. Most notable is the sudden brightening of the optically think component around day 20. We identify this as the time when the blast wave reached the immediate vicinity of the photosphere of the Mira. We have developed a simplified model of the blast wave-wind interaction that can reproduce the gross features of the X-ray evolution of V407 Cyg. If the model is correct, the binary separation is likely to be large and the mass loss rate of the Mira is likely to be relatively low.

The X-Ray Evolution of the Symbiotic Star V407 Cygni During Its 2010 Outburst

NASA Technical Reports Server (NTRS)

Mukai, K.; Nelson, T.; Chomiuk, L.; Donato, D.; Sokoloski, J.

2011-01-01

We present a summary of Swift and Suzaku X-ray observations of the 2010 nova outburst of the symbiotic star, V407 Cyg. The Suzaku spectrum obtained on day 30 indicates the presence of the supersoft component from the white dwarf surface, as well as optically thin component from the shock between the nova ejecta and the Mira wind. The Swift observations then allow us to track the evolution of both components from day 4 to day 150. Most notable is the sudden brightening of the optically think component around day 20. We identify this as the time when the blast wave reached the immediate vicinity of the photosphere of the Mira. We have developed a simplified model of the blast wave-wind interaction that can reproduce the gross features of the X-ray evolution of V407 Cyg. If the model is correct, the binary separation is likely to be large and the mass loss rate of the Mira is likely to be relatively low.

Translations on Eastern Europe, Political, Sociological, and Military Affairs, Number 1554

DTIC Science & Technology

1978-06-28

Macedonian Orthodox Church and president of the Office for Macedonian Emigrees, Zhivko Vasilevski. Taleski Receives Italian Ambassador Skopje NOVA...the development of his homeland, Romania . Starting with the admittance examination, this noble aim is illustrated by the opportunity every candidate...created in Romania and long-term cooperative ties between Romanian and Hungarian writers. Here is a selective list of themes prepared for this year’s

Far Ultraviolet Spectroscopy of Three Long Period Nova-Like Variables, V363 Aur, AC Cnc and RZ Gru

NASA Astrophysics Data System (ADS)

Bisol, Alexandra; Sion, E. M.

2011-01-01

We have selected three nova-like variables: V363 Aur, RZ Gru and AC Cnc, all of which are UX UMa types, having similar orbital periods well beyond the 3 to 4 hour range where most nova-likes are found. All should have very similar secondary stars given the fact that they their physical parameters are so similar. V363 Aur is a bona fide SW Sex star, and AC Cnc is a probable one, while RZ Gru is not a member of the SW Sex subclass. Our objective is to carry out the first synthetic spectral analysis of far ultraviolet spectra of the three systems using state-of-the-art models both of accretion disks and photospheres. Therefore we shall compare the distances we obtain from the best fitting synthetic spectral models to other distance estimates in the literature. We present model-derived accretion rates and distances for all three systems. The FUV flux range of RZ Gru and V363 Aur is dominated by radiation from an optically thick, steady state, accretion but for AC Cnc, we find that a hot white dwarf accounts for 70% of the FUV flux. We compare the FUV characteristics and physical properties of these three long period nova-like systems to the properties of other nova-likes at shorter periods. This work was supported in part by NSF grant AST0807892 to Villanova University.

3D photoionization models of nova V723 Cas

NASA Astrophysics Data System (ADS)

Takeda, L.; Diaz, M.; Campbell, R.; Lyke, J.

2018-01-01

We present modelling and analysis of the ejecta of nova V723 Cas based on spatially resolved infrared spectroscopic data from Keck-OSIRIS, with LGSAO (adaptive optics module). The 3D photoionization models include the shell geometry taken from the observations and an anisotropic radiation field, composed by a spherical central source and an accretion disc. Our simulations indicate revised abundances log(NAl/NH) = -5.4, log(NCa/NH) = -6.4 and log(NSi/NH) = -4.7 in the shell. The total ejected mass was found as Mshell = 1.1 × 10-5 M⊙ and the central source temperature and luminosity are T = 280 000 K and L = 1038 erg s-1. The 3D models are compared to basic 1D simulations to demonstrate the importance of using more realistic treatments, stressing the differences in the shell mass, abundances and characterization of the central source. The possibility of V723 Cas being a neon nova and the puzzling central source features found are discussed.

On the long term evolution of white dwarfs in cataclysmic variables and their recurrence times

NASA Technical Reports Server (NTRS)

Sion, E. M.; Starrfield, S. G.

1985-01-01

The relevance of the long term quasi-static evolution of accreting white dwarfs to the outbursts of Z Andromeda-like symbiotics; the masses and accretion rates of classical nova white dwarfs; and the observed properties of white dwarfs detected optically and with IUE in low M dot cataclysmic variables is discussed. A surface luminosity versus time plot for a massive, hot white dwarf bears a remarkable similarity to the outburst behavior of the hot blue source in Z Andromeda. The long term quasi-static models of hot accreting white dwarfs provide convenient constraints on the theoretically permissible parameters to give a dynamical (nova-like) outburst of classic white dwarfs.

GRB070610: A Curious Galactic Transient

NASA Technical Reports Server (NTRS)

Kasliwal, M. M.; Kulkrarni. S. R.; Cameron, P. B.; Nakar, E.; Ofek, E. O.; Rau, A.; Soderberg, A. M.; Campana, S.; Bloom, J. S.; Perley, D. A.;

GRB 070610: A Curious Galactic Transient

NASA Astrophysics Data System (ADS)

Kasliwal, M. M.; Cenko, S. B.; Kulkarni, S. R.; Cameron, P. B.; Nakar, E.; Ofek, E. O.; Rau, A.; Soderberg, A. M.; Campana, S.; Bloom, J. S.; Perley, D. A.; Pollack, L. K.; Barthelmy, S.; Cummings, J.; Gehrels, N.; Krimm, H. A.; Markwardt, C. B.; Sato, G.; Chandra, P.; Frail, D.; Fox, D. B.; Price, P. A.; Berger, E.; Grebenev, S. A.; Krivonos, R. A.; Sunyaev, R. A.

2008-05-01

GRB 070610 is a typical high-energy event with a duration of 5 s. Yet within the burst localization we detect a highly unusual X-ray and optical transient, Swift J195509.6+261406. We see high-amplitude X-ray and optical variability on very short timescales even at late times. Using near-infrared imaging assisted by a laser guide star and adaptive optics, we identified the counterpart of Swift J195509.6+261406. Late-time optical and near-infrared imaging constrain the spectral type of the counterpart to be fainter than a K-dwarf, assuming it is of Galactic origin. It is possible that GRB 070610 and Swift J195509.6+261406 are unrelated sources. However, the absence of a typical X-ray afterglow from GRB 070610 in conjunction with the spatial and temporal coincidence of the two motivate us to suggest that the sources are related. The closest (imperfect) analog to Swift J195509.6+261406 is V4641 Sgr, an unusual black hole binary. We suggest that Swift J195509.6+261406 along with V4641 Sgr define a subclass of stellar black hole binaries—the fast X-ray novae. We further suggest that fast X-ray novae are associated with bursts of gamma rays. If so, GRB 070610 defines a new class of celestial gamma-ray bursts and these bursts dominate the long-duration GRB demographics.

A White Dwarf at the Limit: V838 Herculis 25 Years After Its Nova Outburst

NASA Astrophysics Data System (ADS)

Garnavich, Peter; Kennedy, Mark; Littlefield, Colin; Szkody, Paula; Mukadam, Anjum

2018-01-01

We present time-resolved photometry and spectroscopy of V838 Her (aka Nova Herculis 1991) a quarter of a century after its unique nova outburst. No new optical observations of the star have been published since the early 1990s. Here, we confirm the presence of deep primary eclipses with a period of 7.14 hours and we detect clear secondary minima. Night-to-night changes of 30% in the system brightness suggests the mass transfer rate is not stable. Spectroscopy reveals absorption features from the secondary star consistent with a K4±1.5 spectral type. From the velocity amplitudes we directly measure the mass ratio of the binary to be q=0.73±0.04. Assuming the secondary is filling its Roche lobe, we estimate the white dwarf mass to be 1.38±0.13 M⊙, consistent with the indirect mass indicators such as the early light curve decay rate and metal abundance in the nebular phase. The mass of the secondary star is also quite high at 1.01±0.06 M⊙. We estimate that the luminosity of the nova peaked at MV = –9.1±0.4 mag, and that its current luminosity is MV = 6.5±0.4 mag.

Deep Space Inquiry

ERIC Educational Resources Information Center

Rapp, Steve

2003-01-01

In this article, the author describes a student-centered research project he introduced to his students. In this research project, his students used images collected by telescopes at Kitt Peak National Optical Observatory (KPNO) to look for novas in the Andromeda Galaxy. This project grew out of the author's experience during a Teachers As Leaders…

Bright gamma-ray emission from TCP J04432130+4721280 (V392 Per) detected by Fermi-LAT

NASA Astrophysics Data System (ADS)

Li, Kwan-Lok; Chomiuk, Laura; Strader, Jay

2018-05-01

We report the Fermi-LAT detection of the optical transient TCP J04432130+4721280 (V392 Per), which was discovered by Yuji Nakamura on 2018-04-29.4740 (CBET #4515) and later identified as a Galactic nova by Wagner et al. (ATel #11588).

Laser program annual report, 1977. Volume 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bender, C.F.; Jarman, B.D.

1978-07-01

An overview is given of the laser fusion program. The solid-state program covers the Shiva and Nova projects. Laser components, control systems, alignment systems, laser beam diagnostics, power conditioning, and optical components are described. The fusion experimental program concerns the diagnostics and data acquisition associated with Argus and Shiva. (MOW)

Models of symbiotic stars

NASA Technical Reports Server (NTRS)

Friedjung, Michael

1993-01-01

One of the most important features of symbiotic stars is the coexistence of a cool spectral component that is apparently very similar to the spectrum of a cool giant, with at least one hot continuum, and emission lines from very different stages of ionization. The cool component dominates the infrared spectrum of S-type symbiotics; it tends to be veiled in this wavelength range by what appears to be excess emission in D-type symbiotics, this excess usually being attributed to circumstellar dust. The hot continuum (or continua) dominates the ultraviolet. X-rays have sometimes also been observed. Another important feature of symbiotic stars that needs to be explained is the variability. Different forms occur, some variability being periodic. This type of variability can, in a few cases, strongly suggest the presence of eclipses of a binary system. One of the most characteristic forms of variability is that characterizing the active phases. This basic form of variation is traditionally associated in the optical with the veiling of the cool spectrum and the disappearance of high-ionization emission lines, the latter progressively appearing (in classical cases, reappearing) later. Such spectral changes recall those of novae, but spectroscopic signatures of the high-ejection velocities observed for novae are not usually detected in symbiotic stars. However, the light curves of the 'symbiotic nova' subclass recall those of novae. We may also mention in this connection that radio observations (or, in a few cases, optical observations) of nebulae indicate ejection from symbiotic stars, with deviations from spherical symmetry. We shall give a historical overview of the proposed models for symbiotic stars and make a critical analysis in the light of the observations of symbiotic stars. We describe the empirical approach to models and use the observational data to diagnose the physical conditions in the symbiotics stars. Finally, we compare the results of this empirical approach with existing models and discuss unresolved problems requiring new observational and theoretical work.

ASAS-SN Discovery of an Unprecedented >1.5 Magnitude Optical Flare from QSO B0346-279

NASA Astrophysics Data System (ADS)

Vallely, P.; Stanek, K. Z.; Kochanek, C. S.; Shields, J. V.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Stritzinger, M.

2018-02-01

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Brutus" telescope in Haleakala, Hawaii, the quadruple 14-cm "Leavitt" telescope in Fort Davis, Texas, the quadruple 14-cm "Payne-Gaposchkin" telescope in Sutherland, South Africa, and the quadruple 14-cm "Cassius" and "Paczynski" telescopes in Cerro Tololo, Chile, we have discovered an unprecedented optical brightening of QSO B0346-279 (z 0.9874).

Ultraviolet spectrophotometry and optical and infrared photometry of the old nova GK Persei

NASA Technical Reports Server (NTRS)

Wu, Chi-Chao; Holm, Albert V.; Panek, Robert J.; Raymond, John C.; Hartmann, Lee W.; Swank, Jean H.

1989-01-01

IUE observations in the 1150-3250-A region were obtained of GK Per during the rise, at the maximum, and during the decline of the 2.5-mag optical outburst in 1981. The results support previous predictions for the interaction of an accretion disk with the magnetic field of an accretion star. The luminosity at minimum is found to be 2.3 solar luminosities, with 1/3 of this being attributed to the cool secondary star.

MicroRNA screening identifies a link between NOVA1 expression and a low level of IKAP in familial dysautonomia

PubMed Central

Hervé, Mylène

2016-01-01

ABSTRACT Familial dysautonomia (FD) is a rare neurodegenerative disease caused by a mutation in intron 20 of the IKBKAP gene (c.2204+6T>C), leading to tissue-specific skipping of exon 20 and a decrease in the synthesis of the encoded protein IKAP (also known as ELP1). Small non-coding RNAs known as microRNAs (miRNAs) are important post-transcriptional regulators of gene expression and play an essential role in the nervous system development and function. To better understand the neuronal specificity of IKAP loss, we examined expression of miRNAs in human olfactory ecto-mesenchymal stem cells (hOE-MSCs) from five control individuals and five FD patients. We profiled the expression of 373 miRNAs using microfluidics and reverse transcription coupled to quantitative PCR (RT-qPCR) on two biological replicate series of hOE-MSC cultures from healthy controls and FD patients. This led to the total identification of 26 dysregulated miRNAs in FD, validating the existence of a miRNA signature in FD. We then selected the nine most discriminant miRNAs for further analysis. The signaling pathways affected by these dysregulated miRNAs were largely within the nervous system. In addition, many targets of these dysregulated miRNAs had been previously demonstrated to be affected in FD models. Moreover, we found that four of our nine candidate miRNAs target the neuron-specific splicing factor NOVA1. We demonstrated that overexpression of miR-203a-3p leads to a decrease of NOVA1, counter-balanced by an increase of IKAP, supporting a potential interaction between NOVA1 and IKAP. Taken together, these results reinforce the choice of miRNAs as potential therapeutic targets and suggest that NOVA1 could be a regulator of FD pathophysiology. PMID:27483351

Infrared outbursts as potential tracers of common-envelope events in high-mass X-ray binary formation

NASA Astrophysics Data System (ADS)

Oskinova, Lidia M.; Bulik, Tomasz; Gómez-Morán, Ada Nebot

2018-06-01

Context. Classic massive binary evolutionary scenarios predict that a transitional common-envelope (CE) phase could be preceded as well as succeeded by the evolutionary stage when a binary consists of a compact object and a massive star, that is, a high-mass X-ray binary (HMXB). The observational manifestations of common envelope are poorly constrained. We speculate that its ejection might be observed in some cases as a transient event at mid-infrared (IR) wavelengths. Aims: We estimate the expected numbers of CE ejection events and HMXBs per star formation unit rate, and compare these theoretical estimates with observations. Methods: We compiled a list of 85 mid-IR transients of uncertain nature detected by the Spitzer Infrared Intensive Transients Survey and searched for their associations with X-ray, optical, and UV sources. Results: Confirming our theoretical estimates, we find that only one potential HMXB may be plausibly associated with an IR-transient and tentatively propose that X-ray source NGC 4490-X40 could be a precursor to the SPIRITS 16az event. Among other interesting sources, we suggest that the supernova remnant candidate [BWL2012] 063 might be associated with SPIRITS 16ajc. We also find that two SPIRITS events are likely associated with novae, and seven have potential optical counterparts. Conclusions: The massive binary evolutionary scenarios that involve CE events do not contradict currently available observations of IR transients and HMXBs in star-forming galaxies.

Spectroscopic Confirmation of TCP J07134590-2112330 as a Galactic Classical Nova in Canis Major

NASA Astrophysics Data System (ADS)

Strader, Jay; Chomiuk, Laura; Bahramian, Arash; Swihart, Sam

2018-03-01

TCP J07134590-2112330 was discovered by Yuji Nakamura on 2018 March 24.5 UT as a 12 mag optical transient. We obtained spectroscopic observations of TCP J07134590-2112330 with the Goodman spectrograph on the 4-m SOAR telescope on 2018 Mar 25.1 UT, with a low-resolution spectrum (R 1200) covering 3850-7850 A. The spectrum indicates that TCP J07134590-2112330 is a young classical nova, with strong hydrogen Balmer emission lines and additional strong lines of [O I] and Fe II. The Balmer lines show P Cygni profiles; the FWHM of the H alpha emission component is 1250 km/s, and the absorption trough extends to -2000 km/s.

A flux calibration device for the SuperNova Integral Field Spectrograph (SNIFS)

NASA Astrophysics Data System (ADS)

Lombardo, Simona; Aldering, Greg; Hoffmann, Akos; Kowalski, Marek; Kuesters, Daniel; Reif, Klaus; Rigault, Michael

2014-07-01

Observational cosmology employing optical surveys often require precise flux calibration. In this context we present SNIFS Calibration Apparatus (SCALA), a flux calibration system developed for the SuperNova Integral Field Spectrograph (SNIFS), operating at the University of Hawaii 2.2 m telescope. SCALA consists of a hexagonal array of 18 small parabolic mirrors distributed over the face of, and feeding parallel light to, the telescope entrance pupil. The mirrors are illuminated by integrating spheres and a wavelength-tunable (from UV to IR) light source, generating light beams with opening angles of 1°. These nearly parallel beams are flat and flux-calibrated at a subpercent level, enabling us to calibrate our "telescope + SNIFS system" at the required precision.

An accreting white dwarf near the Chandrasekhar limit in the Andromeda galaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Sumin; Bildsten, Lars; Wolf, William M.

The intermediate Palomar Transient Factory (iPTF) detection of the most recent outburst of the recurrent nova (RN) system RX J0045.4+4154 in the Andromeda galaxy has enabled the unprecedented study of a massive (M > 1.3 M {sub ☉}) accreting white dwarf (WD). We detected this nova as part of the near-daily iPTF monitoring of M31 to a depth of R ≈ 21 mag and triggered optical photometry, spectroscopy and soft X-ray monitoring of the outburst. Peaking at an absolute magnitude of M{sub R} = –6.6 mag, and with a decay time of 1 mag per day, it is a faintmore » and very fast nova. It shows optical emission lines of He/N and expansion velocities of 1900-2600 km s{sup –1} 1-4 days after the optical peak. The Swift monitoring of the X-ray evolution revealed a supersoft source (SSS) with kT {sub eff} ≈ 90-110 eV that appeared within 5 days after the optical peak, and lasted only 12 days. Most remarkably, this is not the first event from this system, rather it is an RN with a time between outbursts of approximately 1 yr, the shortest known. Recurrent X-ray emission from this binary was detected by ROSAT in 1992 and 1993, and the source was well characterized as a M > 1.3 M {sub ☉} WD SSS. Based on the observed recurrence time between different outbursts, the duration and effective temperature of the SS phase, MESA models of accreting WDs allow us to constrain the accretion rate to M-dot >1.7×10{sup −7} M{sub ⊙} yr{sup −1} and WD mass >1.30 M {sub ☉}. If the WD keeps 30% of the accreted material, it will take less than a Myr to reach core densities high enough for carbon ignition (if made of C/O) or electron capture (if made of O/Ne) to end the binary evolution.« less

Scene Analysis: Non-Linear Spatial Filtering for Automatic Target Detection.

DTIC Science & Technology

1982-12-01

In this thesis, a method for two-dimensional pattern recognition was developed and tested. The method included a global search scheme for candidate...test global switch TYPEO Creating negative video file only.W 11=0 12=256 13=512 14=768 GO 70 2 1 TYPE" Creating negative and horizontally flipped video...purpose was to develop a base of image processing software for the AFIT Digital Signal Processing Laboratory NOVA- ECLIPSE minicomputer system, for

A Far Ultraviolet Spectroscopic Explorer Survey of High-Declination Dwarf Novae

DTIC Science & Technology

2009-08-20

and the occurrence of standstills. It was clas- sified as a Z Camelopardalis system by Notni & Richter (1984). Optical spectra were later obtained by...reddening in the direction of the constellation of Perseus is quite large. To estimate the reddening of FO Per, we note (Table 3) that TZ Per has a

The scientific results of the low energy portion of A-2

NASA Technical Reports Server (NTRS)

Garmire, G.

1979-01-01

Galactic phenomena observed using the HEAO 1 detectors are discussed. A source map of the soft X-ray sky is presented. Specific topics covered include the optical outburst of U Geminorum, low energy RS CVn stars, and the dwarf nova SS Cygni. Aspects of the SS Cygni pulsations are analyzed.

BRITE nanosatellite serendipitously captures oscillatory rise and fall of ASASSN-18fv

NASA Astrophysics Data System (ADS)

Kuschnig, R.; Pigulski, A.; Moffat, A. F. J.; Matthews, J. M.; Zwintz, K.; Baade, D.; Handler, G.; Weiss, W. W.; Wade, G. A.; Rucinski, S. M.; Pablo, H.; Koudelka, O.; Smolec, R.; Popowicz, A.; Neiner, C.; Daszynska-Daszkiewicz, J.; Lovekin, C.; St-Louis, N.; Pamyatnykh, A. A.; Rowe, J.; Orleanski, P.; Mochnacki, S.; Schwarzenberg-Czerny, A.

2018-04-01

One of the five satellites in BRITE-Constellation (http://www.brite-constellation.at/) was obtaining time-series optical photometry of the star HD 92063, only 2 arcmin from the 'Possible, Very Bright Galactic Nova ASASSN-18fv' reported on 21 March 2018 (2018-03-20.32) by ATel #11454.

Optical Photometry of the Nova Outburst TCP J04432130+4721280 (V392 Per)

NASA Astrophysics Data System (ADS)

Konyves-Toth, R.; Csak, B.; Pal, A.; Vinko, J.

2018-05-01

We obtained new photometric observations of TCP J04432130+4721280 (V392 Per, ATel #11588, #11590), R.A = 04:43:21.38, Dec = +47:21:25.9, on 2018-04-30.80 UT. The data were taken with the 60/90 cm Schmidt telescope at Konkoly Observatory, Piszkesteto, Hungary.

New Southern Cataclysmic Variables: Discoveries from MASTER-SAAO

NASA Astrophysics Data System (ADS)

Buckley, D. A. H.; Potter, S. B.; Kniazev, A.; Lipunov, V.; Gorbovskoy, E.; Tiurina, N.

2017-03-01

In this paper we report on new cataclysmic variables (CVs) discovered by the first local optical transient detection system established at the SAAO Sutherland station, namely MASTER-SAAO. The characteristics of the MASTER-SAAO system are described and the parameters of the survey compared to the Catalina Real Time Survey (CRTS). To date MASTER-SAAO has discovered over 200 (non-Solar System) optical transients with about 75% of these being likely new CVs, most being dwarf novae (DNe). Approximately 50% of the DNe have outburst amplitudes in excess of 4 magnitudes, with some extreme amplitude (> 7 mag), probable WZ Sge systems. The MASTER-SAAO detection limit of B = 19-20 is comparable to the ˜20 magnitude limit of the CRTS (depending on CV colour). Based on the CV detection statistics of CRTS, we believe that MASTER-SAAO is detecting essentially the same CV population as CRTS, for a detection outburst amplitude threshold >2.2 magnitudes. We also present results of the initial follow-up program on CVs discovered by MASTER, including dwarf novae, a bright new VY Scl system and a new eclipsing polar.

Serendipitous discovery of a dwarf Nova in the Kepler field near the G dwarf KIC 5438845

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, Alexander; Ayres, Thomas R.; Neff, James E.

2015-02-01

The Kepler satellite provides a unique window into stellar temporal variability by observing a wide variety of stars with multi-year, near-continuous, high precision, optical photometric time series. While most Kepler targets are faint stars with poorly known physical properties, many unexpected discoveries should result from a long photometric survey of such a large area of sky. During our Kepler Guest Observer programs that monitored late-type stars for starspot and flaring variability, we discovered a previously unknown dwarf nova that lies within a few arcseconds of the mid-G dwarf star KIC 5438845. This dwarf nova underwent nine outbursts over a 4more » year time span. The two largest outbursts lasted ∼17–18 days and show strong modulations with a 110.8 minute period and a declining amplitude during the outburst decay phase. These properties are characteristic of an SU UMa-type cataclysmic variable. By analogy with other dwarf nova light curves, we associate the 110.8 minute (1.847 hr) period with the superhump period, close to but slightly longer than the orbital period of the binary. No precursor outbursts are seen before the super-outbursts and the overall super-outburst morphology corresponds to Osaki and Meyer “Case B” outbursts, which are initiated when the outer edge of the disk reaches the tidal truncation radius. “Case B” outbursts are rare within the Kepler light curves of dwarf novae. The dwarf nova is undergoing relatively slow mass transfer, as evidenced by the long intervals between outbursts, but the mass transfer rate appears to be steady, because the smaller “normal” outbursts show a strong correlation between the integrated outburst energy and the elapsed time since the previous outburst. At super-outburst maximum the system was at V ∼ 18, but in quiescence it is fainter than V ∼ 22, which will make any detailed quiescent follow-up of this system difficult.« less

X-Ray Emission from an Asymmetric Blast Wave and a Massive White Dwarf in the Gamma Ray Emitting Nova V407 CYG

NASA Technical Reports Server (NTRS)

Nelson, Thomas; Donato, Davide; Mukai, Koji; Sokoloski, Jennifer; Chomiuk, Laura

2012-01-01

Classical nova events in symbiotic stars, although rare, offer a unique opportunity to probe the interaction between ejecta and a dense environment in stellar explosions. In this work, we use X-ray data obtained with Swift and Suzaku during the recent classical nova outburst in V407 Cyg to explore such an interaction. We find evidence of both equilibrium and non-equilibrium ionization plasmas at the time of peak X-ray brightness, indicating a strong asymmetry in the density of the emitting region. Comparing a simple model to the data, we find that the X-ray evolution is broadly consistent with nova ejecta driving a forward shock into the dense wind of the Mira companion. We detect a highly absorbed soft X-ray component in the spectrum during the first 50 days of the outburst that is consistent with supersoft emission from the nuclear burning white dwarf. The high temperature and short turn off time of this emission component, in addition to the observed breaks in the optical and UV lightcurves, indicate that the white dwarf in the binary is extremely massive. Finally, we explore the connections between the X-ray and GeV-ray evolution, and propose that the gamma ray turn-off is due to the stalling of the forward shock as the ejecta reach the red giant surface.

Optical evolution of Nova Ophiuchi 2007 = V2615 Oph

NASA Astrophysics Data System (ADS)

Munari, U.; Henden, A.; Valentini, M.; Siviero, A.; Dallaporta, S.; Ochner, P.; Tomasoni, S.

2008-06-01

The moderately fast Nova Oph 2007 reached maximum brightness on 2007 March 28 at V= 8.52, B-V=+1.12, V-RC=+0.76, V-IC=+1.59 and RC-IC=+0.83, after fast initial rise and a pre-maximum halt lasting a week. Decline times were tV2= 26.5, tB2= 30, tV3= 48.5 and tB3= 56.5 d. The distance to the nova is d= 3.7 ± 0.2 kpc, the height above the Galactic plane is z= 215 pc, the reddening is E(B-V) = 0.90 and the absolute magnitude at maximum is MmaxV=-7.2 and MmaxB=-7.0. The spectrum four days before maximum resembled a F6 supergiant, in an agreement with broad-band colours. It later developed into that of a standard `Fe ii'-class nova. Nine days past maximum, the expansion velocity estimated from the width of Hα emission component was ˜730 km s-1, and the displacement from it of the principal and diffuse-enhanced absorption systems was ˜650 and 1380 km s-1, respectively. Dust probably formed and disappeared during the period from 82 to 100 d past maximum, causing (at peak dust concentration) an extinction of ΔB= 1.8 mag and an extra ΔE(B-V) = 0.44 reddening.

FUSE SPECTROSCOPIC ANALYSIS OF THE SLOWEST SYMBIOTIC NOVA AG PEG DURING QUIESCENCE

NASA Astrophysics Data System (ADS)

Sion, Edward Michael; Godon, Patrick; Katynski, Marcus; Mikolajewska, Joanna

2018-01-01

We present a far ultraviolet spectroscopic analysis of the slowest known symbiotic nova AG Peg (MIII giant + hot white dwarf; P_orb = 818.4 days) which underwent a nova explosion in 1850 followed by a very slow decline that did not end until ~ 1996, marking the beginning of queiscence. Eight years of quiescence ended in June 2015, when AG Peg exhibited a Z And-type outburst with an optical amplitude of ~ 3 magnitudes. We have carried out accretion disk and WD photosphere synthetic spectral modeling of a FUSE spectrum (Froning et al. 2014) obtained on June 5.618, 2003 during the quiescence intervai ~ 12 years before the 2015 outburst. The spectrum is heavily affected by ISM absorption as well as strong broad emission lines. We de-reddened the FUSE fluxes with E(B-V) = 0.10 which is the maximum galactic reddening in the direction of AG Peg and took the distance of 800 pc (Kenyon et al. 1993) but used a range of white dwarf masses, surface temperatures and disk inclination angles. Our analysis also incororates archival HST FOS spectra obtained in 1996 at the onset of quiescence, 147 years after the 1850 nova explosion. The results of our analysis are presented and implications are discussed.This work is supported in part by NASA ADP grant NNX17AF36G to Villanova University.

Direct measurement of astrophysically important resonances in 38K(p ,γ )39Ca

NASA Astrophysics Data System (ADS)

Christian, G.; Lotay, G.; Ruiz, C.; Akers, C.; Burke, D. S.; Catford, W. N.; Chen, A. A.; Connolly, D.; Davids, B.; Fallis, J.; Hager, U.; Hutcheon, D.; Mahl, A.; Rojas, A.; Sun, X.

2018-02-01

Background: Classical novae are cataclysmic nuclear explosions occurring when a white dwarf in a binary system accretes hydrogen-rich material from its companion star. Novae are partially responsible for the galactic synthesis of a variety of nuclides up to the calcium (A ˜40 ) region of the nuclear chart. Although the structure and dynamics of novae are thought to be relatively well understood, the predicted abundances of elements near the nucleosynthesis endpoint, in particular Ar and Ca, appear to sometimes be in disagreement with astronomical observations of the spectra of nova ejecta. Purpose: One possible source of the discrepancies between model predictions and astronomical observations is nuclear reaction data. Most reaction rates near the nova endpoint are estimated only from statistical model calculations, which carry large uncertainties. For certain key reactions, these rate uncertainties translate into large uncertainties in nucleosynthesis predictions. In particular, the 38K(" close=")p ,γ )">p ,γ 39Ca reaction has been identified as having a significant influence on Ar, K, and Ca production. In order to constrain the rate of this reaction, we have performed a direct measurement of the strengths of three candidate ℓ =0 resonances within the Gamow window for nova burning, at 386 ±10 keV, 515 ±10 keV, and 689 ±10 keV. Method: The experiment was performed in inverse kinematics using a beam of unstable 38K impinged on a windowless hydrogen gas target. The 39Ca recoils and prompt γ rays from 38K, 39Ca reactions were detected in coincidence using a recoil mass separator and a bismuth-germanate scintillator array, respectively. Results: For the 689 keV resonance, we observed a clear recoil-γ coincidence signal and extracted resonance strength and energy values of 120-30+50(stat.)-60 +20(sys .) meV and 679-1+2(stat .) ±1 (sys .) keV , respectively. We also performed a singles analysis of the recoil data alone, extracting a resonance strength of 120 ±20 (stat .)±15 (sys .) meV, consistent with the coincidence result. For the 386 keV and 515 keV resonances, we extract 90 % confidence level upper limits of 2.54 meV and 18.4 meV, respectively. Conclusions: We have established a new recommended 38K(p ,γ ) 39Ca rate based on experimental information, which reduces overall uncertainties near the peak temperatures of nova burning by a factor of ˜250 . Using the rate obtained in this work in model calculations of the hottest oxygen-neon novae reduces overall uncertainties on Ar, K, and Ca synthesis to factors of 15 or less in all cases.

On the decay of outbursts in dwarf novae nad X-ray novae

NASA Technical Reports Server (NTRS)

Cannizzo, John K.

1994-01-01

We perform computations using a time-dependent model for the accretion disk limit-cycle mechanism to examine the decay of the optical light following the peak of a dwarf nova outburst. We present the results of a parameter study of the physical input variables which affect the decay rate. In the model, the decay is brought about by a cooling transition front which begins at large radii in the disk and moves inward. The nature of the decay is strongly influenced by the radial dependence of the accretion disk viscosity parameter alpha. To obtain exponential decays for typical dwarf nova parameters, we require alpha proportional to r(exp epsilon(sub 0)), where epsilon(sub 0) approximately = 0.3-0.4. The exact value of epsilon(sub 0) which produces exponential decays depends on factors such as the mass of the accreting star and the inner radius of the accretion disk. Therefore, the observed ubiquity of exponential decays in two different types of systems (dwarf novae and X-ray novae) leads us to believe that alpha is an unnatural scaling for the viscosity. The physics of the cooling transition front must be self-regulating in that the timescale (-parital derivative of lnSigma(r)/partial derivative +)(exp -1) (where Sigma is the surface density) for mass extraction across the front remains constant. This may be consistent with a scaling alpha proportional to (h/r)(exp n), where h is the local disk semi-thickness and n approximately 1-2. As regards the speed of the cooling front, we find v(sub F)(r) proportional to r(exp p), where p approximately 3 at large radii, with an abrupt transition to p approximately 0 at some smaller radius. The r(exp 3) dependence is much steeper than has been found by previous workers and appears to result from the strong variation of specific heat within the cooling front when the front resides at a large radius in the disk. The outflow of disk material across the cooling front causes a significant departure of dln T(sub dff0/dln r from the standard value of -0.75 (expected from steady state accretion) within about 0.2 dex in radius of the break associated with the cooling front -- T(sub eff) aproximately 10(exp 3.9) K (r/10(exp 10 cm)) (exp -0.1). These effects should be observable with eclipse mapping. Finally, it appears that the relatively slow decay rate for the optical flux in the 1975 outburst of A0620-00 can be accounted for if the primary is a approximately 10 Solar mass black hole.

Search for active-sterile neutrino mixing using neutral-current interactions in NOvA

NASA Astrophysics Data System (ADS)

Adamson, P.; Aliaga, L.; Ambrose, D.; Anfimov, N.; Antoshkin, A.; Arrieta-Diaz, E.; Augsten, K.; Aurisano, A.; Backhouse, C.; Baird, M.; Bambah, B. A.; Bays, K.; Behera, B.; Bending, S.; Bernstein, R.; Bhatnagar, V.; Bhuyan, B.; Bian, J.; Blackburn, T.; Bolshakova, A.; Bromberg, C.; Brown, J.; Brunetti, G.; Buchanan, N.; Butkevich, A.; Bychkov, V.; Campbell, M.; Catano-Mur, E.; Childress, S.; Choudhary, B. C.; Chowdhury, B.; Coan, T. E.; Coelho, J. A. B.; Colo, M.; Cooper, J.; Corwin, L.; Cremonesi, L.; Cronin-Hennessy, D.; Davies, G. S.; Davies, J. P.; Derwent, P. F.; Dharmapalan, R.; Ding, P.; Djurcic, Z.; Dukes, E. C.; Duyang, H.; Edayath, S.; Ehrlich, R.; Feldman, G. J.; Frank, M. J.; Gabrielyan, M.; Gallagher, H. R.; Germani, S.; Ghosh, T.; Giri, A.; Gomes, R. A.; Goodman, M. C.; Grichine, V.; Groh, M.; Group, R.; Grover, D.; Guo, B.; Habig, A.; Hartnell, J.; Hatcher, R.; Hatzikoutelis, A.; Heller, K.; Himmel, A.; Holin, A.; Howard, B.; Hylen, J.; Jediny, F.; Judah, M.; Kafka, G. K.; Kalra, D.; Kasahara, S. M. S.; Kasetti, S.; Keloth, R.; Kolupaeva, L.; Kotelnikov, S.; Kourbanis, I.; Kreymer, A.; Kumar, A.; Kurbanov, S.; Lackey, T.; Lang, K.; Lee, W. M.; Lin, S.; Lokajicek, M.; Lozier, J.; Luchuk, S.; Maan, K.; Magill, S.; Mann, W. A.; Marshak, M. L.; Matera, K.; Matveev, V.; Méndez, D. P.; Messier, M. D.; Meyer, H.; Miao, T.; Miller, W. H.; Mishra, S. R.; Mohanta, R.; Moren, A.; Mualem, L.; Muether, M.; Mufson, S.; Murphy, R.; Musser, J.; Nelson, J. K.; Nichol, R.; Niner, E.; Norman, A.; Nosek, T.; Oksuzian, Y.; Olshevskiy, A.; Olson, T.; Paley, J.; Patterson, R. B.; Pawloski, G.; Pershey, D.; Petrova, O.; Petti, R.; Phan-Budd, S.; Plunkett, R. K.; Poling, R.; Potukuchi, B.; Principato, C.; Psihas, F.; Radovic, A.; Rameika, R. A.; Rebel, B.; Reed, B.; Rocco, D.; Rojas, P.; Ryabov, V.; Sachdev, K.; Sail, P.; Samoylov, O.; Sanchez, M. C.; Schroeter, R.; Sepulveda-Quiroz, J.; Shanahan, P.; Sheshukov, A.; Singh, J.; Singh, J.; Singh, P.; Singh, V.; Smolik, J.; Solomey, N.; Song, E.; Sousa, A.; Soustruznik, K.; Strait, M.; Suter, L.; Talaga, R. L.; Tas, P.; Thayyullathil, R. B.; Thomas, J.; Tian, X.; Tognini, S. C.; Tripathi, J.; Tsaris, A.; Urheim, J.; Vahle, P.; Vasel, J.; Vinton, L.; Vold, A.; Vrba, T.; Wang, B.; Wetstein, M.; Whittington, D.; Wojcicki, S. G.; Wolcott, J.; Yadav, N.; Yang, S.; Zalesak, J.; Zamorano, B.; Zwaska, R.; NOvA Collaboration

2017-10-01

We report results from the first search for sterile neutrinos mixing with active neutrinos through a reduction in the rate of neutral-current interactions over a baseline of 810 km between the NOvA detectors. Analyzing a 14-kton detector equivalent exposure of 6.05 ×1020 protons-on-target in the NuMI beam at Fermilab, we observe 95 neutral-current candidates at the Far Detector compared with 83.5 ±9.7 (stat ) ±9.4 (syst ) events predicted assuming mixing only occurs between active neutrino species. No evidence for νμ→νs transitions is found. Interpreting these results within a 3 +1 model, we place constraints on the mixing angles θ24<20.8 ° and θ34<31.2 ° at the 90% C.L. for 0.05 eV2≤Δ m412≤0.5 eV2 , the range of mass splittings that produce no significant oscillations over the Near Detector baseline.

Disk irradiation and light curves of x ray novae

NASA Technical Reports Server (NTRS)

Kim, S.-W.; Wheeler, J. C.; Mineshige, S.

1994-01-01

We study the disk instability and the effect of irradiation on outbursts in the black hole X-ray nova system. In both the optical and soft X-rays, the light curves of several X-ray novae, A0620-00, GH 2000+25, Nova Muscae 1991 (GS 1124-68), and GRO J0422+32, show a main peak, a phase of exponential decline, a secondary maximum or reflare, and a final bump in the late decay followed by a rapid decline. Basic disk thermal limit cycle instabilities can account for the rapid rise and overall decline, but not the reflare and final bump. The rise time of the reflare, about 10 days, is too short to represent a viscous time, so this event is unlikely to be due to increased mass flow from the companion star. We explore the possibility that irradiation by X-rays produced in the inner disk can produce these secondary effects by enhancing the mass flow rate within the disk. Two plausible mechanisms of irradiation of the disk are considered: direct irradiation from the inner hot disk and reflected radiation from a corona or other structure above the disk. Both of these processes will be time dependent in the context of the disk instability model and result in more complex time-dependent behavior of the disk structure. We test both disk instability and mass transfer burst models for the secondary flares in the presence of irradiation.

Evidence for a massive stellar black hole in x ray Nova Muscae

NASA Technical Reports Server (NTRS)

Chen, Wan; Gehrels, Neil; Cheng, F. H.

1992-01-01

We present evidence that the X-ray Nova Muscae system contains a massive, greater than 10 M solarmass, black hole. A recently measured photometric binary mass function gives the black hole mass for this system as a function of orbital inclination angle. From the spectral redshift and width of the positron annihilation gamma-ray line observed by GRANAT/SIGMA, we find the accretion disk inclination angle to be 22 deg plus or minus 18 deg. Assuming the accretion disk lies in the orbital plane of the system, the black hole mass is found to have a lower limit of 14 M solar mass although statistics are poor. This is supported by spectral modeling of combined optical/UV/x-ray/gamma-ray data and by a new Nova Muscae distance limit we derive of greater than 3 kpc. The large mass for this black hole and the high binary mass ratio it implies (greater than 20) raise a serious challenge to theoretical models of the formation and evolution of massive binaries. The gamma-ray line technique introduced here can give tight constraints on orbital parameters when high-sensitivity line measurements are made by such missions as GRO.

Ultraviolet studies of nova-like variables with the IUE

NASA Technical Reports Server (NTRS)

Guinan, E. F.

1983-01-01

KQ Mon is a new UX UMa-type nova-like variable. Optical spectra taken in 1978 reveal very shallow Balmer absorption lines and He I (wavelength 4471) absorption. There was no evidence of orbital variations but the appearance of the optical spectrum and the presence of low amplitude flickering suggested a strong similarity to CD-42 degrees 14462 (=V3885 Sgr) and other members of the UX UMa class. KQ Mon was observed at low dispersion with the IUE satellite. Six spectra taken with the short wavelength prime (SWP) camera are dominated by strong broad absorption lines due to N V, O I, Si III, Si IV, C IV, He II, N IV, and A1 III. There is little evidence of orbital phase modulation over the time baseline of the observations. Unlike UV observations of other UX UMa-type objects, KQ Mon exhibits no emission lines or P Cygni-type profiles and the velocity displacements appear to be smaller, suggesting the absence of a hot, high velocity wind characterizing other UX UMa stars. The relationship of KQ Mon to other UX UMa disk stars is discussed and a model is suggested to explain their observed properties and the lack of major outbursts.

The Accretion Disk and the Boundary Layer of the Symbiotic Recurrent Nova T Corona Borealis

NASA Astrophysics Data System (ADS)

Mukai, Koji; Luna, Gerardo; Nelson, Thomas; Sokoloski, Jennifer L.; Lucy, Adrian; Nuñez, Natalia

2017-08-01

T Corona Borealis is one of four known Galactic recurrent symbiotic novae, red giant-white dwarf binaries from which multiple thermonuclear runaway (TNR) events, or nova eruptions, have been observed. TNR requires high pressure at the base of the accreted envelope, and a recurrence time of less than a century almost certainly requires both high white dwarf mass and high accretion rate. The eruptions of T CrB were observed in 1866 and 1946; if the 80 year interval is typical, the next eruption would be expected within the next decade or two. Optical observations show that T CrB has entered a super-active state starting in 2015, similar to that seen in 1938, 8 years before the last eruption. In quiescence, T CrB is a known, bright hard X-ray source that has been detected in the Swift/BAT all-sky survey. Here we present the result of our NuSTAR observation of T CrB in 2015, when it had started to brighten but had not yet reached the peak of the super-active state. We were able to fit the spectrum with an absorbed cooling flow model with reflection, with a reflection amplitude of 1.0. We also present recent Swift and XMM-Newton observations during the peak of the super-active state, when T CrB had faded dramatically in the BAT band. T CrB is found to be much more luminous in the UV, while the X-ray spectrum became complex including a soft, optically thick component. We present our interpretation of the overall variability as due to instability of a large disk, and of the X-rays as due to emission from the boundary layer. In our view, the NuSTAR observation was performed when the boundary layer was optically thin, and the reflection was only from the white dwarf surface that subtended 2π steradian of the sky as seen from the emission region. With these assumptions, we infer the white dwarf in the T CrB system to have a mass of ~1.2 Msun. During the very active state, the boundary layer had turned partially optically thick and produced the soft X-ray component, while drastically reducing the hard X-ray luminosity. We will discuss the implication of variable accretion on the total mass accumulated since the last eruption.

Typical examples of classical novae

NASA Technical Reports Server (NTRS)

Hack, Margherita; Selvelli, Pierluigi; Bianchini, Antonio; Duerbeck, Hilmar W.

1993-01-01

Because of the very complicated individualistic behavior of each nova, we think it necessary to review the observations of a few well-observed individuals. We have selected a few objects of different speed classes, which have been extensively observed. They are: V1500 Cygni 1975, a very fast nova; V603 Aql 1918, fast nova; CP Pup 1942, fast nova; GK Per 1901, fast nova; V 1668 Cyg 1979, moderately fast nova; FH Ser 1970, slow nova; DQ Her 1934, slow nova; T Aur 1891, slow nova; RR Pic 1925, slow nova; and HR Del 1967, very slow nova.

Typical examples of classical novae

NASA Astrophysics Data System (ADS)

Hack, Margherita; Selvelli, Pierluigi; Bianchini, Antonio; Duerbeck, Hilmar W.

1993-09-01

Because of the very complicated individualistic behavior of each nova, we think it necessary to review the observations of a few well-observed individuals. We have selected a few objects of different speed classes, which have been extensively observed. They are: V1500 Cygni 1975, a very fast nova; V603 Aql 1918, fast nova; CP Pup 1942, fast nova; GK Per 1901, fast nova; V 1668 Cyg 1979, moderately fast nova; FH Ser 1970, slow nova; DQ Her 1934, slow nova; T Aur 1891, slow nova; RR Pic 1925, slow nova; and HR Del 1967, very slow nova.

Hubble COS Spectroscopy of the Dwarf Nova CW Mon: The White Dwarf in Quiescence?

PubMed

Hause, Connor; Sion, Edward M; Godon, Patrick; Boris, T Gänsicke; Szkody, Paula; de Martino, Domitilla; Pala, Anna

2017-08-01

We present a synthetic spectral analysis of the HST COS spectrum of the U Geminorum-type dwarf nova CW Mon, taken during quiescence as part of our COS survey of accreting white dwarfs in Cataclysmic Variables. We use synthetic photosphere and optically thick accretion disk spectra to model the COS spectrum as well as archival IUE spectra obtained decades ago when the system was in an even deeper quiescent state. Assuming a reddening of E(B-V)=0.06, an inclination of 60° (CW Mon has eclipses of the accretion disk, and a white dwarf mass of 0.8 M ⊙ , our results indicate the presence of a 22-27,000 K white dwarf and a low mass accretion rate [Formula: see text], for a derived distance o ~200 to ~300 pc.

A 60-NIGHT Campaign on Dwarf Novae - Part One - Photometric Variability of Su-Ursae and Yz-Cancri

NASA Astrophysics Data System (ADS)

van Paradijs, J.; Charles, P. A.; Harlaftis, E. T.; Arevalo, M. J.; Baruch, J. E. F.; Callanan, P. J.; Casares, J.; Dhillon, V. S.; Gimenez, A.; Gonzalez, R.; Matinez-Pais, I. G.; Jones, D. H. P.; Hassall, B. J. M.; Hellier, C.; Kidger, M. R.; Lazaro, C.; Marsh, T. R.; Mason, K. O.; Mukai, K.; Naylor, T.; Reglero, V.; Rutten, R. G. M.; Smith, R. C.

1994-04-01

A 60-night campaign on SU UMa, YZ Cnc and some secondary targets was carried out during 1988 December and 1989 January at the Observatorio del Roque de Los Muchachos (the 1988 International Time Project). The aim was to study the behaviour of these dwarf novae through their outburst cycle. Here we present the overall light curves of the main targets, SU UMa and YZ Cnc, which show that the optical fluxes continue to decrease after the end of the outburst. For YZ Cnc we find that, during quiescence, orbital variability is present, which may be interpreted as modulation caused by the bright-spot region. Near the end of an outburst, a weak, sinusoidal variation is observed; we discuss the possibility that this arises either from the secondary star or the accretion disc.

Outflows from Compact Objects in Supernovae and Novae

NASA Astrophysics Data System (ADS)

Vlasov, Andrey Dmitrievich

Originally thought of as a constant and unchanging place, the Universe is full of dramas of stars emerging, dying, eating each other, colliding, etc. One of the first transient phenomena noticed were called novae (the name means "new" in Latin). Years later, supernovae were discovered. Despite their names, both novae and supernovae are events in relatively old stars, with supernovae marking the point of stellar death. Known for thousands of years, supernovae and novae remain among the most studied events in our Universe. Supernovae strongly influence the circumstellar medium, enriching it with heavy elements and shocking it, facilitating star formation. Cosmic rays are believed to be accelerated in shocks from supernovae, with small contribution possibly coming from novae. Even though the basic physics of novae is understood, many questions remain unanswered. These include the geometry of the ejecta, why some novae are luminous radio or gamma-ray sources and others are not, what is the ultimate fate of recurrent novae, etc. Supernova explosions are the primary sources of elements heavier than hydrogen and helium. The elements up to nuclear masses A around 100 can form through successive nuclear fusion in the cores of stars starting with hydrogen. Beyond iron, the fusion becomes endothermic instead of exothermic. In addition, for these nuclear masses the temperatures required to overcome the Coulomb barriers are so high that the nuclei are dissociated into alpha particles and free nucleons. Hence all elements heavier than A around 100 should have formed by some other means. These heavier nuclear species are formed by neutron capture on seed nuclei close to or heavier than iron-group nuclei. Depending on the ratio between neutron-capture timescale and beta-decay timescale, neutron-capture processes are called rapid or slow (r- and s-processes, respectively). The s-process, which occurs near the valley of stable isotopes, terminates at Bi (Z=83), because after Bi there is a gap of four elements with no stable isotopes (Po, At, Rn, Ac) until we come to stable Th. The significant abundance of Th and U in our Universe therefore implies the presence of a robust source of r-process. The astrophysical site of r-process is still under debate. Here we present a study of a candidate site for r-process, neutrino-heated winds from newly-formed strongly magnetized, rapidly rotating neutron stars ("proto-magnetars"). Even though we find such winds are incapable of synthesizing the heaviest r-process elements like U and Th, they produce substantial amounts of weak r-process (38 Supernova explosions are the primary sources of elements heavier than hydrogen and helium. The elements up to nuclear masses A around 100 can form through successive nuclear fusion in the cores of stars starting with hydrogen. Beyond iron, the fusion becomes endothermic instead of exothermic. In addition, for these nuclear masses the temperatures required to overcome the Coulomb barriers are so high that the nuclei are dissociated into alpha particles and free nucleons. Hence all elements heavier than A around 100 should have formed by some other means. These heavier nuclear species are formed by neutron capture on seed nuclei close to or heavier than iron-group nuclei. Depending on the ratio between neutron-capture timescale and beta-decay timescale, neutron-capture processes are called rapid or slow (r- and s-processes, respectively). The s-process, which occurs near the valley of stable isotopes, terminates at Bi (Z=83), because after Bi there is a gap of four elements with no stable isotopes (Po, At, Rn, Ac) until we come to stable Th. The significant abundance of Th and U in our Universe therefore implies the presence of a robust source of r-process. The astrophysical site of r-process is still under debate. Here we present a study of a candidate site for r-process, neutrino-heated winds from newly-formed strongly magnetized, rapidly rotating neutron stars ("proto-magnetars"). Even though we find such winds are incapable of synthesizing the heaviest r-process elements like U and Th, they produce substantial amounts of weak r-process (38.

Spectroscopic classification of SN 2018brz as a type Ia supernova before maximum

NASA Astrophysics Data System (ADS)

Galbany, Lluis; Lopez-Sanchez, Angel R.; Ascasibar, Yago; Fiegert, Kristin

2018-05-01

We report the spectroscopic classification of SN 2018brz (RA=08:33:22.27, DEC=-76:37:39.8) in an anonymous host galaxy. The candidate was discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN: Shappee et al. 2014) on UT 2018-05-15 at 16.5 mag. Observations were performed on the 4m Anglo-Australian Telescope at Siding Spring Observatory on 2018 May 19 9:15 UT, using Koala+AAOmega and Grisms 580V+1000R (3500-6000A and 6300-7300A).

VizieR Online Data Catalog: The Taurus-Auriga ecosystem. I. (Kraus+, 2017)

NASA Astrophysics Data System (ADS)

Kraus, A. L.; Herczeg, G. J.; Rizzuto, A. C.; Mann, A. W.; Slesnick, C. L.; Carpenter, J. M.; Hillenbrand, L. A.; Mamajek, E. E.

2017-11-01

High-resolution spectroscopic observations for 35 candidates from the surveys of Slesnick+ (2006, J/AJ/132/2665) and Li & Hu (1998, J/A+AS/132/173) were previously obtained with Keck/HIRES on 2006 December 12 and 13 (PIs Carpenter and Slesnick). We downloaded these observations, extracted the spectra, and analyzed them to measure the radial velocity, Hα equivalent width, and Li equivalent width for each object. We observed 32 candidates with the SuperNova Integral Field Spectrograph (SNIFS) on the University of Hawaii 2.2m telescope between 2014 November and 2015 January (PIs Herczeg and Mann). These observations (R~1000) are similar to those described by Mann+ (2015, J/ApJ/804/64), who describe some of the observations and reductions in more detail. See section 3 for further details. (9 data files).

First Searches for Optical Counterparts to Gravitational-wave Candidate Events

NASA Astrophysics Data System (ADS)

Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.; Anderson, R. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Austin, L.; Aylott, B. E.; Babak, S.; Baker, P. T.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barker, D.; Barnum, S. H.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J.; Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Behnke, B.; Bejger, M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.; Bergmann, G.; Berliner, J. M.; Bertolini, A.; Bessis, D.; Betzwieser, J.; Beyersdorf, P. T.; Bhadbhade, T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Blom, M.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogan, C.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Bose, S.; Bosi, L.; Bowers, J.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brannen, C. A.; Brau, J. E.; Breyer, J.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brückner, F.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K. C.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Castiglia, A.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow, J.; Christensen, N.; Chu, Q.; Chua, S. S. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Colombini, M.; Constancio, M., Jr.; Conte, A.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; Dayanga, T.; De Rosa, R.; Debreczeni, G.; Degallaix, J.; Del Pozzo, W.; Deleeuw, E.; Deléglise, S.; Denker, T.; Dereli, H.; Dergachev, V.; DeRosa, R.; DeSalvo, R.; Dhurandhar, S.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Díaz, M.; Dietz, A.; Dmitry, K.; Donovan, F.; Dooley, K. L.; Doravari, S.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edwards, M.; Effler, A.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Endrőczi, G.; Essick, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fang, Q.; Farr, B.; Farr, W.; Favata, M.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R.; Flaminio, R.; Foley, E.; Foley, S.; Forsi, E.; Forte, L. A.; Fotopoulos, N.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fujimoto, M.-K.; Fulda, P.; Fyffe, M.; Gair, J.; Gammaitoni, L.; Garcia, J.; Garufi, F.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Griffo, C.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hall, B.; Hall, E.; Hammer, D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Heefner, J.; Heidmann, A.; Heintze, M.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.; Horrom, T.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hu, Y.; Hua, Z.; Huang, V.; Huerta, E. A.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Iafrate, J.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Iyer, B. R.; Izumi, K.; Jacobson, M.; James, E.; Jang, H.; Jang, Y. J.; Jaranowski, P.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; K, Haris; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasprzack, M.; Kasturi, R.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufman, K.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kéfélian, F.; Keitel, D.; Kelley, D. B.; Kells, W.; Keppel, D. G.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, B. K.; Kim, C.; Kim, K.; Kim, N.; Kim, W.; 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.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak, D.; Kremin, A.; Kringel, V.; Krishnan, B.; Królak, A.; Kucharczyk, C.; Kudla, S.; Kuehn, G.; Kumar, A.; Kumar, P.; Kumar, R.; Kurdyumov, R.; Kwee, P.; Landry, M.; Lantz, B.; Larson, S.; Lasky, P. D.; Lawrie, C.; Lazzarini, A.; Le Roux, A.; Leaci, P.; Lebigot, E. O.; Lee, C.-H.; Lee, H. K.; Lee, H. M.; Lee, J.; Lee, J.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levine, B.; Lewis, J. B.; Lhuillier, V.; Li, T. G. F.; Lin, A. C.; Littenberg, T. B.; Litvine, V.; Liu, F.; Liu, H.; Liu, Y.; Liu, Z.; Lloyd, D.; Lockerbie, N. A.; Lockett, V.; Lodhia, D.; Loew, K.; Logue, J.; Lombardi, A. L.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Luan, J.; Lubinski, M. J.; Lück, H.; Lundgren, A. P.; Macarthur, J.; Macdonald, E.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magana-Sandoval, F.; Mageswaran, M.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Manca, G. M.; Mandel, I.; Mandic, V.; Mangano, V.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Martinelli, L.; Martynov, D.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; May, G.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McIver, J.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Meier, T.; Melatos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.; Mikhailov, E. E.; Milano, L.; Miller, J.; Minenkov, Y.; Mingarelli, C. M. F.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Mohan, M.; Mohapatra, S. R. P.; Mokler, F.; Moraru, D.; Moreno, G.; Morgado, N.; Mori, T.; 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.; Nanda Kumar, D.; Nardecchia, I.; Nash, T.; Naticchioni, L.; Nayak, R.; Necula, V.; Neri, I.; Newton, G.; Nguyen, T.; Nishida, E.; Nishizawa, A.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E.; Nuttall, L. K.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oppermann, P.; O'Reilly, B.; Ortega Larcher, W.; O'Shaughnessy, R.; Osthelder, C.; Ottaway, D. J.; Ottens, R. S.; Ou, J.; Overmier, H.; Owen, B. J.; Padilla, C.; Pai, A.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.; Paoletti, R.; Papa, M. A.; Paris, H.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Pedraza, M.; Peiris, P.; Penn, S.; Perreca, A.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pierro, V.; Pinard, L.; Pindor, B.; Pinto, I. M.; Pitkin, M.; Poeld, J.; Poggiani, R.; Poole, V.; Poux, C.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.; Quintero, E.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Raja, S.; Rajalakshmi, G.; Rakhmanov, M.; Ramet, C.; Rapagnani, P.; Raymond, V.; Re, V.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen, R.; Riles, K.; Robertson, N. A.; Robinet, F.; Rocchi, A.; Roddy, S.; Rodriguez, C.; Rodruck, M.; Roever, C.; Rolland, L.; Rollins, J. G.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Salemi, F.; Sammut, L.; Sandberg, V.; Sanders, J.; Sannibale, V.; Santiago-Prieto, I.; Saracco, E.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R.; Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schreiber, E.; Schuette, D.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sergeev, A.; Shaddock, D.; Shah, S.; Shahriar, M. S.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siellez, K.; Siemens, X.; Sigg, D.; Simakov, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G. R.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Soden, K.; Son, E. J.; Sorazu, B.; Souradeep, T.; Sperandio, L.; Staley, A.; Steinert, E.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stevens, D.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szeifert, G.; Tacca, M.; Talukder, D.; Tang, L.; Tanner, D. B.; Tarabrin, S. P.; Taylor, R.; ter Braack, A. P. M.; Thirugnanasambandam, M. P.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C. V.; Torrie, C. I.; Travasso, F.; Traylor, G.; Tse, M.; Ugolini, D.; Unnikrishnan, C. S.; Vahlbruch, H.; Vajente, G.; Vallisneri, M.; van den Brand, J. F. J.; Van Den Broeck, C.; van der Putten, S.; 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, P. J.; Venkateswara, K.; Verkindt, D.; Verma, S.; Vetrano, F.; Viceré, A.; Vincent-Finley, R.; Vinet, J.-Y.; Vitale, S.; Vlcek, B.; Vo, T.; Vocca, H.; Vorvick, C.; Vousden, W. D.; Vrinceanu, D.; Vyachanin, S. P.; Wade, A.; Wade, L.; Wade, M.; Waldman, S. J.; Walker, M.; Wallace, L.; Wan, Y.; Wang, J.; Wang, M.; Wang, X.; Wanner, A.; Ward, R. L.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Wibowo, S.; Wiesner, K.; Wilkinson, C.; Williams, L.; Williams, R.; Williams, T.; Willis, J. L.; Willke, B.; Wimmer, M.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yancey, C. C.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yum, H.; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, F.; Zhang, L.; Zhao, C.; Zhu, H.; Zhu, X. J.; Zotov, N.; Zucker, M. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration; Akerlof, C.; Baltay, C.; Bloom, J. S.; Cao, Y.; Cenko, S. B.; Ćwiek, A.; Ćwiok, M.; Dhillon, V.; Fox, D. B.; Gal-Yam, A.; Kasliwal, M. M.; Klotz, A.; Laas-Bourez, M.; Laher, R. R.; Law, N. M.; Majcher, A.; Małek, K.; Mankiewicz, L.; Nawrocki, K.; Nissanke, S.; Nugent, P. E.; Ofek, E. O.; Opiela, R.; Piotrowski, L.; Poznanski, D.; Rabinowitz, D.; Rapoport, S.; Richards, J. W.; Schmidt, B.; Siudek, M.; Sokołowski, M.; Steele, I. A.; Sullivan, M.; Żarnecki, A. F.; Zheng, W.

2014-03-01

During the Laser Interferometer Gravitational-wave Observatory and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type.

First Searches for Optical Counterparts to Gravitational-Wave Candidate Events

NASA Technical Reports Server (NTRS)

Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.;

Optical Photometric Observations of M31N 2008-12a: Pre- and Post-maximum of the 2017 Eruption

NASA Astrophysics Data System (ADS)

Naito, H.; Watanabe, F.; Sano, Y.; Kuramoto, K.; Itagaki, K.; Kiyota, S.; Arai, A.; Maehara, H.; Matsumoto, K.; Fukui, A.; Nishiyama, K.; Kabashima, F.; Henze, M.; Darnley, M. J.; Shafter, A. W.; Kato, M.; et al.

2018-01-01

We report additional multicolor photometry of the 2017 outburst of the remarkable recurrent nova M31N 2008-12a (ATels #11116, #11117, #11118, #11121, #11124, #11125, #11126, #11130, see Darnley et al. 2014, 2015, 2016 and Henze et al. 2014, 2015a, 2015b for comprehensive multi-wavelength light curves of previous eruptions).

Supernova and optical transient observations using the three wide-field telescope array of the KMTNet

NASA Astrophysics Data System (ADS)

Moon, Dae-Sik; Kim, Sang Chul; Lee, Jae-Joon; Pak, Mina; Park, Hong Soo; He, Matthias Y.; Antoniadis, John; Ni, Yuan Qi; Lee, Chung-Uk; Kim, Seung-Lee; Park, Byeong-Gon; Kim, Dong-Jin; Cha, Sang-Mok; Lee, Yongseok; Gonzalez, Santiago

2016-08-01

The Korea Microlensing Telescope Network (KMTNet) is a network of three new 1.6-m, wide-field telescopes spread over three different sites in Chile, South Africa and Australia. Each telescope is equipped with a four square degree wide-field CCD camera, making the KMTNet an ideal facility for discovering and monitoring early supernovae and other rapidly evolving optical transients by providing 24-hour continuous sky coverage. We describe our inaugurating program of observing supernovae and optical transients using about 20% of the KMTNet time in 2015-2019. Our early results include detection of infant supernovae, novae and peculiar transients as well as numerous variable stars and low surface brightness objects such as dwarf galaxies.

Discovery of the optical counterpart of the transient X-ray burster Centaurus X-4

NASA Technical Reports Server (NTRS)

Canizares, C. R.; Mcclintock, J. E.; Grindlay, J. E.

1980-01-01

The paper deals with the discovery and subsequent study of the optical counterpart to an X-ray nova which is almost certainly the historical transient Centaurus X-4, first discovered in 1969 and then dormant for the past decade. It is shown that Cen X-4 is a clear example of a soft, transient X-ray burster. The most important consequence of the connection between bursters and soft transients is the support it gives to the hypothesis that bursters are accreting neutron stars in binary systems. The observations support the hypothesis that at least some of the light comes from an accretion disk, and that X-ray heating plays an important role in the optical emission.

Evidence for GeV cosmic rays from white dwarfs in the local cosmic ray spectra and in the gamma-ray emissivity of the inner Galaxy

NASA Astrophysics Data System (ADS)

Kamae, Tuneyoshi; Lee, Shiu-Hang; Makishima, Kazuo; Shibata, Shinpei; Shigeyama, Toshikazu

2018-03-01

Recent observations found that electrons are accelerated to ˜10 GeV and emit synchrotron hard X-rays in two magnetic white dwarfs (WDs), also known as cataclysmic variables (CVs). In nova outbursts of WDs, multi-GeV gamma-rays were detected, implying that protons are accelerated to 100 GeV or higher. In recent optical surveys, the WD density is found to be higher near the Sun than in the Galactic disk by a factor ˜2.5. The cosmic rays (CRs) produced by local CVs and novae will accumulate in the local bubble for 106-107 yr. On these findings, we search for CRs from historic CVs and novae in the observed CR spectra. We model the CR spectra at the heliopause as sums of Galactic and local components based on observational data as much as possible. The initial Galactic CR electron and proton spectra are deduced from the gamma-ray emissivity, the local electron spectrum from the hard X-ray spectra at the CVs, and the local proton spectrum from gamma-ray spectra at novae. These spectral shapes are then expressed in a simple set of polynomial functions of CR energy and regressively fitted until the high-energy (>100 GeV) CR spectra near Earth and the Voyager-1 spectra at the heliopause are reproduced. We then extend the modeling to nuclear CR spectra and find that one spectral shape fits all local nuclear CRs, and that the apparent hardening of the nuclear CR spectra is caused by the roll-down of local nuclear spectra around 100-200 GeV. All local CR spectra populate a limited energy band below 100-200 GeV and enhance gamma-ray emissivity below ˜10 GeV. Such an enhancement is observed in the inner Galaxy, suggesting the CR fluxes from CVs and novae are substantially higher there.

NOVA2-mediated RNA regulation is required for axonal pathfinding during development.

PubMed

Saito, Yuhki; Miranda-Rottmann, Soledad; Ruggiu, Matteo; Park, Christopher Y; Fak, John J; Zhong, Ru; Duncan, Jeremy S; Fabella, Brian A; Junge, Harald J; Chen, Zhe; Araya, Roberto; Fritzsch, Bernd; Hudspeth, A J; Darnell, Robert B

2016-05-25

The neuron specific RNA-binding proteins NOVA1 and NOVA2 are highly homologous alternative splicing regulators. NOVA proteins regulate at least 700 alternative splicing events in vivo, yet relatively little is known about the biologic consequences of NOVA action and in particular about functional differences between NOVA1 and NOVA2. Transcriptome-wide searches for isoform-specific functions, using NOVA1 and NOVA2 specific HITS-CLIP and RNA-seq data from mouse cortex lacking either NOVA isoform, reveals that NOVA2 uniquely regulates alternative splicing events of a series of axon guidance related genes during cortical development. Corresponding axonal pathfinding defects were specific to NOVA2 deficiency: Nova2-/- but not Nova1-/- mice had agenesis of the corpus callosum, and axonal outgrowth defects specific to ventral motoneuron axons and efferent innervation of the cochlea. Thus we have discovered that NOVA2 uniquely regulates alternative splicing of a coordinate set of transcripts encoding key components in cortical, brainstem and spinal axon guidance/outgrowth pathways during neural differentiation, with severe functional consequences in vivo.

Search for active-sterile neutrino mixing using neutral-current interactions in NOvA

DOE PAGES

Adamson, P.; Aliaga, L.; Ambrose, D.; ...

2017-10-30

Here, we report results from the first search for sterile neutrinos mixing with active neutrinos through a reduction in the rate of neutral-current interactions over a baseline of 810 km between the NOvA detectors. Analyzing a 14-kton detector equivalent exposure of 6.05 × 10 20 protons-on-target in the NuMI beam at Fermilab, we observe 95 neutral-current candidates at the Far Detector compared with 83.5 ± 9.7(stat) ± 9.4(syst) events predicted assuming mixing only occurs between active neutrino species. No evidence for νμ→νs transitions is found. Interpreting these results within a 3+1 model, we place constraints on the mixing angles θ 24more » < 20.8° and θ 34 < 31.2° at the 90% C.L. for 0.05 eV 2 ≤ Δm 41 2 ≤ 0.5 eV 2, the range of mass splittings that produce no significant oscillations over the Near Detector baseline.« less

Observations of GAIA-identified Cataclysmic Variables Using the TUBITAK National Observatory

NASA Astrophysics Data System (ADS)

Esenoglu, Hasan H.; Kirbiyik, Halil; Kaynar, Suleyman; Okuyan, Oguzhan; Hamitoglu, Irek; Galeev, Almaz; Uluc, Kadir; Kocak, Murat; Kilic, Sila E.; Parmaksizoglu, Murat; Erece, Orhan; Ozisik, Tuncay; Gulsecen, Hulusi

2016-07-01

TUBITAK National Observatory supports the GAIA alerts with observations using three telescopes (RTT150, T100, T60) at the site with a limited time quota. We have observed 10 variable stars among GAIA sources discovered in the years 2014-2016 that may be candidate Cataclysmic Variables (CVs). Our TUG observations at this stage involve photometry and spectroscopy to aid the identification of these sources. The first preliminary result of our observations of Gaia14aat among them showed a dwarf nova outburst with an amplitude of 2.69 mag. We aim to construct a GAIA astrophysics group to study CVs along with supported studies using the SRG (Spectrum Roentgen Gamma astrophysical observatory) after the year of 2016. These observations will basically involve spectroscopy, narrow-band CCD imaging and photometry using several filters to aid the identification of these sources. RTT150 observations with very narrow filters (like H-alpha, SII, OIII with band width of range of 2 to 5 nm) will reveal whether shell around the SRG sources to aid identification novae among them.

MIT's role in project Apollo. Volume 2: Optical, radar, and candidate subsystems

NASA Technical Reports Server (NTRS)

1972-01-01

The development of optical, radar, and candidate subsystems for Project Apollo is discussed. The design and development of the optical subsystems for both the Apollo command and lunar spacecraft are described. Design approaches, problems, and solutions are presented. The evolution of radar interfaces with the GN&C system is discussed; these interfaces involved both hardware and software in a relatively complex interrelationship. The design and development of three candidate subsystems are also described. The systems were considered for use in Apollo, but were not incorporated into the final GN&C system. The three subsystems discussed are the star tracker-horizon photometer, the map and data viewer and the lunar module optical rendezvous system.

Inertial Confinement Fusion Quarterly Report: April--June 1993. Volume 3, Number 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacGowan, B.J.; Kotowski, M.; Schleich, D.

1993-11-01

This issue of the ICF Quarterly contains six articles describing recent advances in Lawrence Livermore National Laboratory`s inertial confinement fusion (ICF) program. The current emphasis of the ICF program is in support of DOE`s National Ignition Facility (NIF) initiative for demonstrating ignition and gain with a 1-2 MJ glass laser. The articles describe recent Nova experiments and investigations tailored towards enhancing understanding of the key physics and technological issues for the NIF. Titles of the articles are: development of large-aperture KDP crystals; inner-shell photo-ionized X-ray lasers; X-ray radiographic measurements of radiation-driven shock and interface motion in solid density materials; themore » role of nodule defects in laser-induced damage of multilayer optical coatings; techniques for Mbar to near-Gbar equation-of-state measurements with the Nova laser; parametric instabilities and laser-beam smoothing.« less

Hubble COS Spectroscopy of the Dwarf Nova CW Mon: The White Dwarf in Quiescence?1

PubMed Central

Hause, Connor; Sion, Edward M.; Godon, Patrick; Boris, T. Gänsicke; Szkody, Paula; de Martino, Domitilla; Pala, Anna

2018-01-01

We present a synthetic spectral analysis of the HST COS spectrum of the U Geminorum-type dwarf nova CW Mon, taken during quiescence as part of our COS survey of accreting white dwarfs in Cataclysmic Variables. We use synthetic photosphere and optically thick accretion disk spectra to model the COS spectrum as well as archival IUE spectra obtained decades ago when the system was in an even deeper quiescent state. Assuming a reddening of E(B−V)=0.06, an inclination of 60° (CW Mon has eclipses of the accretion disk, and a white dwarf mass of 0.8M⊙, our results indicate the presence of a 22–27,000 K white dwarf and a low mass accretion rate (M˙≲10−10M⊙/yr), for a derived distance o ~200 to ~300 pc. PMID:29430023

High-velocity winds from a dwarf nova during outburst

NASA Technical Reports Server (NTRS)

Cordova, F. A.; Mason, K. O.

1982-01-01

An ultraviolet spectrum of the dwarf nova TW Vir during an optical outburst shows shortward-shifted absorption features with edge velocities as high as 4800 km/s, about the escape velocity of a white dwarf. A comparison of this spectrum with the UV spectra of other cataclysmic variables suggests that mass loss is evident only for systems with relatively high luminosities (more than about 10 solar luminosities) and low inclination angles with respect to the observer's line of sight. The mass loss rate for cataclysmic variables is of order 10 to the -11th solar mass per yr; this is from 0.01 to 0.001 of the mass accretion rate onto the compact star in the binary. The mass loss may occur by a mechanism similar to that invoked for early-type stars, i.e., radiation absorbed in the lines accelerates the accreting gas to the high velocities observed.

Outer planets mission television subsystem optics study

NASA Technical Reports Server (NTRS)

1972-01-01

An optics study was performed to establish a candidate optical system design for the proposed NASA Mariner Jupiter/Saturn 77 mission. The study was performed over the 6-month period from January through June 1972. The candidate optical system contains both a wide angle (A) and a narrow angle (B) lens. An additional feature is a transfer mirror mechanism that allows image transfer from the B lens to the vidicon initially used for the A lens. This feature adds an operational redundancy to the optical system in allowing for narrow angle viewing if the narrow angle vidicon were to fail. In this failure mode, photography in the wide angle mode would be discontinued. The structure of the candidate system consists mainly of aluminum with substructures of Invar for athermalization. The total optical system weighs (excluding vidicons) approximately 30 pounds and has overall dimensions of 26.6 by 19.5 by 12.3 inches.

NOVA2-mediated RNA regulation is required for axonal pathfinding during development

PubMed Central

Saito, Yuhki; Miranda-Rottmann, Soledad; Ruggiu, Matteo; Park, Christopher Y; Fak, John J; Zhong, Ru; Duncan, Jeremy S; Fabella, Brian A; Junge, Harald J; Chen, Zhe; Araya, Roberto; Fritzsch, Bernd; Hudspeth, A J; Darnell, Robert B

2016-01-01

The neuron specific RNA-binding proteins NOVA1 and NOVA2 are highly homologous alternative splicing regulators. NOVA proteins regulate at least 700 alternative splicing events in vivo, yet relatively little is known about the biologic consequences of NOVA action and in particular about functional differences between NOVA1 and NOVA2. Transcriptome-wide searches for isoform-specific functions, using NOVA1 and NOVA2 specific HITS-CLIP and RNA-seq data from mouse cortex lacking either NOVA isoform, reveals that NOVA2 uniquely regulates alternative splicing events of a series of axon guidance related genes during cortical development. Corresponding axonal pathfinding defects were specific to NOVA2 deficiency: Nova2-/- but not Nova1-/- mice had agenesis of the corpus callosum, and axonal outgrowth defects specific to ventral motoneuron axons and efferent innervation of the cochlea. Thus we have discovered that NOVA2 uniquely regulates alternative splicing of a coordinate set of transcripts encoding key components in cortical, brainstem and spinal axon guidance/outgrowth pathways during neural differentiation, with severe functional consequences in vivo. DOI: http://dx.doi.org/10.7554/eLife.14371.001 PMID:27223325

The SSS classical nova V5116 Sgr

NASA Astrophysics Data System (ADS)

Sala, G.; Ness, J.; Greiner, J.; Hernanz, M.

2017-10-01

XMM-Newton observed the nova V5116 Sgr during its supersoft phase (SSS). V5116 Sgr showed a decrease of the flux by a factor around 8 during 2/3 of the orbital period. The broad band EPIC spectra remain unchanged during the different flux phases, suggesting an occultation of the central source in a high inclination system. While the global SED does not change significantly, the RGS spectrum is changing between the high and the low flux phases. The non-occultation phase shows a typical white dwarf atmosphere spectrum, dominated by absorption lines. During the low flux periods an extra component of emission lines is superimposed to the soft X-ray continuum. This supports the picture of V5116 Sgr as the clearest example of a system switching between the SSa class of SSS novae, with spectra dominated by absorption lines, and the SSe class, showing an emission lines component. In addition, the simultaneous OM images allow us to find a phase solution for the X-ray light-curve. A thick rim of the accretion disk as the one developed for the SSSs CAL 87, RX J0019.8, and RX J0513.9 could provide a plausible model both for the optical and the X-ray light curve of V5116 Sgr.

Dust, Abundances, and the Evolution of Novae

NASA Astrophysics Data System (ADS)

Woodward, Charles; Bode, Michael; Evans, Anuerin; Geballe, Thomas; Gehrz, Robert; Helton, Andrew; Krautter, Joachim; Lynch, David; Ness, Jan-Uwe; Rudy, Richard; Schwarz, Greg; Shore, Steve; Starrfield, Sumner; Truran, James; Vanlandingham, Karen; Wagner, R. Mark

2008-03-01

Evolved stars are the engines of energy production and chemical evolution in our Universe. They deposit radiative and mechanical energy into their environments. They enrich the ambient ISM with elements synthesized in their interiors and dust grains condensed in their atmospheres. Classical novae (CNe) contribute to this cycle of chemical enrichment through explosive nucleosynthesis and the violent ejection of material dredged from the white dwarf progenitor and mixed with the accreted surface layers. Our capstone study of 10 CNe will provide an ensemble of objects, well-populated in CNe parameter space (fast, slow, 'coronal', dusty) for detailed photoionization modeling and analysis. CNe are laboratories in which several poorly-understood astrophysical processes (e.g., mass transfer, thermonuclear runaway, optically thick winds, common envelope evolution, molecule and grain formation, coronal emission) may be observed. With Spitzer's unique wavelength coverage and point-source sensitivity we can: (i) investigate the in situ formation, astromineralogy, and processing of nova dust, (ii) determine the ejecta elemental abundances resulting from thermonuclear runaway, (iii) constrain the correlation of ejecta mass with progenitor type, (iv) measure the bolometric luminosity of the outburst, and (v) characterize the kinematics and structure of the ejected envelopes. Extensive ground-based and space-based (Chandra, Swift, XMM-Newton) programs led by team CoIs will complement Spitzer CNe observations.

Featured Image: Identifying a Glowing Shell

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2018-05-01

New nebulae are being discovered and classified every day and this false-color image reveals one of the more recent objects of interest. This nebula, IPHASX J210204.7+471015, was recently imaged by the Andalucia Faint Object Spectrograph and Camera mounted on the 2.5-m Nordic Optical Telescope in La Palma, Spain. J210204 was initially identified as a possible planetary nebula a remnant left behind at the end of a red giants lifetime. Based on the above imaging, however, a team of authors led by Martn Guerrero (Institute of Astrophysics of Andalusia, Spain) is arguing that this shell of glowing gas was instead expelled around a classical nova. In a classical nova eruption, a white dwarf and its binary companion come very close together, and mass transfers to form a thin atmosphere of hydrogen around the white dwarf. When this hydrogen suddenly ignites in runaway fusion, this outer atmosphere can be expelled, forming a short-lived nova remnant which is what Guerrero and collaborators think were seeing with J210204. If so, this nebula can reveal information about the novathat caused it. To find out more about what the authors learned from this nebula, check out the paper below.CitationMartn A. Guerrero et al 2018 ApJ 857 80. doi:10.3847/1538-4357/aab669

DEEP NEAR-IR OBSERVATIONS OF THE GLOBULAR CLUSTER M4: HUNTING FOR BROWN DWARFS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dieball, A.; Bedin, L. R.; Knigge, C.

2016-01-20

We present an analysis of deep Hubble Space Telescope (HST)/Wide Field Camera 3 near-IR (NIR) imaging data of the globular cluster (GC) M4. The best-photometry NIR color–magnitude diagram (CMD) clearly shows the main sequence extending toward the expected end of the hydrogen-burning limit and going beyond this point toward fainter sources. The white dwarf (WD) sequence can be identified. As such, this is the deepest NIR CMD of a GC to date. Archival HST optical data were used for proper-motion cleaning of the CMD and for distinguishing the WDs from brown dwarf (BD) candidates. Detection limits in the NIR aremore » around F110W ≈ 26.5 mag and F160W ≈ 27 mag, and in the optical around F775W ≈ 28 mag. Comparing our observed CMDs with theoretical models, we conclude that we have reached beyond the H-burning limit in our NIR CMD and are probably just above or around this limit in our optical–NIR CMDs. Thus, any faint NIR sources that have no optical counterpart are potential BD candidates, since the optical data are not deep enough to detect them. We visually inspected the positions of NIR sources that are fainter than the H-burning limit in F110W and for which the optical photometry did not return a counterpart. We found in total five sources for which we did not get an optical measurement. For four of these five sources, a faint optical counterpart could be visually identified, and an upper optical magnitude was estimated. Based on these upper optical magnitude limits, we conclude that one source is likely a WD, one source could be either a WD or BD candidate, and the remaining two sources agree with being BD candidates. No optical counterpart could be detected for just one source, which makes this source a good BD candidate. We conclude that we found in total four good BD candidates.« less

A challenge to identify an optical counterpart of the gravitational wave event GW151226 with Hyper Suprime-Cam†

NASA Astrophysics Data System (ADS)

Utsumi, Yousuke; Tominaga, Nozomu; Tanaka, Masaomi; Morokuma, Tomoki; Yoshida, Michitoshi; Asakura, Yuichiro; Finet, François; Furusawa, Hisanori; Kawabata, Koji S.; Liu, Wei; Matsubayashi, Kazuya; Moritani, Yuki; Motohara, Kentaro; Nakata, Fumiaki; Ohta, Kouji; Terai, Tsuyoshi; Uemura, Makoto; Yasuda, Naoki

2018-01-01

We present the results of detailed analysis of an optical imaging survey conducted using the Subaru/Hyper Suprime-Cam (HSC) that aimed to identify an optical counterpart to the gravitational wave event GW151226. In half a night, the i- and z-band imaging survey by HSC covered 63.5 deg2 of the error region, which contains about 7% of the LIGO localization probability, and the same field was observed in three different epochs. The detectable magnitude of the candidates in a differenced image is evaluated as i ˜ 23.2 mag for the requirement of at least two 5 σ detections, and 1744 candidates are discovered. Assuming a kilonova as an optical counterpart, we compare the optical properties of the candidates with model predictions. A red and rapidly declining light curve condition enables the discrimination of a kilonova from other transients, and a small number of candidates satisfy this condition. The presence of stellar-like counterparts in the reference frame suggests that the surviving candidates are likely to be flare stars. The fact that most of those candidates are in the galactic plane, |b| < 5°, supports this interpretation. We also check whether the candidates are associated with the nearby GLADE galaxies, which reduces the number of contaminants even with a looser color cut. When a better probability map (with localization accuracy of ˜50 deg2) is available, kilonova searches of up to approximately 200 Mpc will become feasible by conducting immediate follow-up observations with an interval of 3-6 d.

AT Cnc: A SECOND DWARF NOVA WITH A CLASSICAL NOVA SHELL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shara, Michael M.; Mizusawa, Trisha; Zurek, David

2012-10-20

We are systematically surveying all known and suspected Z Cam-type dwarf novae for classical nova shells. This survey is motivated by the discovery of the largest known classical nova shell, which surrounds the archetypal dwarf nova Z Camelopardalis. The Z Cam shell demonstrates that at least some dwarf novae must have undergone classical nova eruptions in the past, and that at least some classical novae become dwarf novae long after their nova thermonuclear outbursts, in accord with the hibernation scenario of cataclysmic binaries. Here we report the detection of a fragmented 'shell', 3 arcmin in diameter, surrounding the dwarf novamore » AT Cancri. This second discovery demonstrates that nova shells surrounding Z Cam-type dwarf novae cannot be very rare. The shell geometry is suggestive of bipolar, conical ejection seen nearly pole-on. A spectrum of the brightest AT Cnc shell knot is similar to that of the ejecta of the classical nova GK Per, and of Z Cam, dominated by [N II] emission. Galaxy Evolution Explorer FUV imagery reveals a similar-sized, FUV-emitting shell. We determine a distance of 460 pc to AT Cnc, and an upper limit to its ejecta mass of {approx}5 Multiplication-Sign 10{sup -5} M {sub Sun }, typical of classical novae.« less

Determination of SBS induced damage limits in large fused silica optics for intense, time varying laser pulses

NASA Astrophysics Data System (ADS)

Kyrazis, D. T.; Weiland, T. L.

1990-10-01

The propagation of intense 3rd harmonic light (0.351 micron) through large optical components of the Nova laser results in fracture damage of the center of the component. This damage is caused by an intense acoustical wave brought to focus in the center by reflecting off the circular edge of the optic. The source of this wave is light generated by transverse stimulated Brillouin scattering (SBS). By taking into account the transient gain characteristics of the SBS, the pulse energy can be correctly predicted that would cause damage for any time variation in intensity in the pump beam, and predict the relative intensity of the Brillouin light. The model is based on the transient behavior of a first order linear system.

Common Envelope Ejection for a Luminous Red Nova in M101

DOE PAGES

Blagorodnova, N.; Kotak, R.; Polshaw, J.; ...

2017-01-06

We present the results of optical, near-infrared, and mid-infrared observations of M101 OT2015-1 (PSN J14021678+5426205), a luminous red transient in the Pinwheel galaxy (M101), spanning a total of 16 years. The light curve showed two distinct peaks with absolute magnitudes M r ≤ -12.4 and M r ~ -12, on 2014 November 11 and 2015 February 17, respectively. The spectral energy distributions during the second maximum show a cool outburst temperature of ≈3700 K and low expansion velocities (≈-300 km s -1) for the H I, Ca II, Ba II, and K I lines. From archival data spanning 15-8 yearsmore » before the outburst, we find a single source consistent with the optically discovered transient, which we attribute to being the progenitor; it has properties consistent with being an F-type yellow supergiant with L ~8.7×10 4 L ⊙, T eff ≈ 7000 K, and an estimated mass of M1 = 18 ± 1 M ⊙ . This star has likely just finished the H-burning phase in the core, started expanding, and is now crossing the Hertzsprung gap. Based on the combination of observed properties, we argue that the progenitor is a binary system, with the more evolved system overfilling the Roche lobe. Comparison with binary evolution mode ls suggests that the outburst was an extremely rare phenomenon, likely associated with the ejection of the common envelope of a massive star. Finally, the initial mass of the primary fills the gap between the merger candidates V838 Mon (5-10 M ⊙) and NGC 4490-OT (30M ⊙).« less

Galex and Optical Observations of GW Librae during the Long Decline from Superoutburst

NASA Technical Reports Server (NTRS)

Bullock, Eric; Szkody, Paula; Mukadam, Anjum S.; Borges, Bernardo W.; Fraga, Luciano; Gansicke, Boris T.; Harrison, Thomas E.; Henden, Arne; Holtzman, Jon; Howell, Steve B.;

The spectroscopic evolution of the recurrent nova T Pyxidis during its 2011 outburst. III. The ultraviolet development from iron curtain through the post-X-ray turnoff

NASA Astrophysics Data System (ADS)

De Gennaro Aquino, I.; Shore, S. N.; Schwarz, G. J.; Mason, E.; Starrfield, S.; Sion, E. M.

2014-02-01

We continue the analysis of the multiwavelength evolution of the recurrent nova T Pyx during its 2011 outburst, focussing on the spectral development on the 1150-3000 Å region. This extraordinary data set presents the longest temporal baseline high resolution view of the ultraviolet for any nova to date (classical or recurrent). The observations cover the early Fe-curtain stage, when the UV was completely optically thick, to 834 days after discovery when the outburst was effectively over. We present an analysis of dynamics and abundances of the interstellar species whose resonance lines are accessible in the UV. The Lyα profile is consistent with only interstellar absorption at all epochs and agrees with the H I 21 cm column density. The distance obtained to T Pyx is about 5 kpc, based on the ISM analysis. For the ejecta evolution we have been able to follow the changes in ionization and structure with previously unobtained resolution and cadence. The excited state isoelectronic transitions of C III, N IV], and O V displayed the same detached absorption lines as the optical He I transitions during the optical maximum. This is explained as resonance absorption within the ejecta of FUV ground state lines from the 300-1000 Å range. The resonance lines of all species showed absorption components between -1000 and -3000 km s-1 as soon as the Fe-curtain turned transparent (from day 105); these persisted at the same velocities and varied in strength from one ion to another through day 834. The last ultraviolet spectrum, taken more than 800 days after outburst, showed the same absorption lines on N V and C IV as day 105. There was no evidence of circumstellar absorbers. This and the related observations of profile evolution effectively rule out any wind model for the spectrum. The picture that emerges is of ejecta that became optically thin after visual maximum as the X-ray emission became visible following an outwardly propagating ionization front and for which the ionization stages froze because of ejecta expansion after the end of the soft X-ray illumination. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

The Space Infrared Interferometric Telescope (SPIRIT): Optical System Design Considerations

NASA Technical Reports Server (NTRS)

Wilson, Mark E.; Leisawitz, David; Martino, Anthony J.; Budinoff, Jason; Quijada, Manuel; Hyde, Tupper

2007-01-01

SPIRIT is a candidate NASA Origins Probe mission. It is a spatial and spectral interferometer operating at 4 K with an operating wavelength range 25 - 400 microns. This paper describes the various components of the candidate optical system, including telescopes, pointing and tracking optics, along with their functions. Some of the tradeoffs involved in selecting various components, with their particular characteristics, are described.

High-cadence Multi-color Observations of the Dwarf Nova KSP-OT-201503a by the KMTNet Supernova Program

NASA Astrophysics Data System (ADS)

Brown, Shannon; Moon, Dae-Sik; Ni, Yuan Qi; Drout, Maria; Antoniadis, John; Afsariardchi, Niloufar; Cha, Sang-Mok; Lee, Yongseok

2018-06-01

We report multicolor BVI monitoring and spectroscopic classification of the dwarf nova KSP-OT-201503a. The transient was detected by the Korean Microlensing Telescope Network (KMTNet) Supernova Program (KSP) in 2015 March, reached a peak apparent magnitude V ≃ 17.3 mag from a quiescent magnitude V ≃ 22.6 mag, and lasted for approximately 17 days. Our high-cadence sampling allows us to identify distinctive phases consisting of a rapid ascent, a main outburst composed of a flat plateau followed by a gradual dimming, and a quick decline. We observe the sharp transition between the ascent phase and main outburst phase, likely related to the deceleration of the heating front as it passes through the accretion disk. These features in the light curves indicate that the outburst is outside-in. Archival data reveal the outburst history of the source, showing at least three outbursts between 2011 and 2015. These are equally separated by approximately 25 months, though we find a recurrence time as short as 189 days is compatible with the archival data. An optical spectrum obtained 701 days from outburst peak shows prominent Balmer emission lines superimposed on a blue continuum, consistent with a cataclysmic variable in quiescence. The outburst properties of KSP-OT-201503a closely resemble those of U Gem-type dwarf novae usually associated with younger, longer-period systems above the period gap of 2–3 hr observed in cataclysmic variables. This suggests that the source may be a rare U Gem-type dwarf nova with a long recurrence time, though we are unable to rule out the possibility that KSP-OT-201503a lies below the period gap.

Request to monitor 0103+59 HT Cas, 0809-76 Z Cha, 1004-69 OY Car AND Request to monitor 2147+13 LS Peg AND Request to monitor 1743-12 V378 Ser (Nova Ser 2005)

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2005-06-01

AAVSO Alert Notice 317 has three topics. First: Drs. Christopher Mauche (Lawrence Livermore National Laboratory), Peter Wheatley (Univ. of Leicester), and Koji Mukai (NASA GSFC) have obtained time on XMM-Newton to observe HT Cas, Z Cha, or OY Car in outburst. AAVSO assistance is requested in monitoring these stars closely so we can inform them promptly when any of them go into outburst. Very prompt notification is essential, because the satellite requires 2-4 days to move to the target after the observations are triggered, and the superoutbursts of OY Car and Z Cha last only about 10 days, while the HT Cas outbursts last only a little more than 2 days. Second: Dr. Darren Baskill (Univ. of Leicester) has requested optical observations of LS Peg (currently suspected as being a DQ Her nova-like) to coincide with upcoming observations by XMM-Newton. Observations are requested from now until July 8, with time series 12 hours before and after, and also during the XMM observation. Use an Ic or V filter (Ic preferred), maximum time precision, S/N=100. Third: Dr. Alon Retter (Penn State Univ.) has requested AAVSO assistance in observing V378 Ser (Nova Serpentis 2005). Please monitor V378 Ser over the coming weeks as the nova fades and report your observations to the AAVSO. Both visual and CCD observations are encouraged. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

The 2011 Outburst of Recurrent Nova T Pyx: X-Ray Observations Expose the White Dwarf Mass and Ejection Dynamics

NASA Technical Reports Server (NTRS)

Chomiuk, Laura; Nelson, Thomas; Mukai, Koji; Solokoski, J. L.; Rupen, Michael P.; Page, Kim L.; Osborne, Julian P.; Kuulkers, Erik; Mioduszewski, Amy J.; Roy, Nirupam;

The 2011 outburst of recurrent nova T Pyx: X-ray observations expose the white dwarf mass and ejection dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chomiuk, Laura; Nelson, Thomas; Mukai, Koji

2014-06-20

The recurrent nova T Pyx underwent its sixth historical outburst in 2011, and became the subject of an intensive multi-wavelength observational campaign. We analyze data from the Swift and Suzaku satellites to produce a detailed X-ray light curve augmented by epochs of spectral information. X-ray observations yield mostly non-detections in the first four months of outburst, but both a super-soft and hard X-ray component rise rapidly after Day 115. The super-soft X-ray component, attributable to the photosphere of the nuclear-burning white dwarf, is relatively cool (∼45 eV) and implies that the white dwarf in T Pyx is significantly below themore » Chandrasekhar mass (∼1 M {sub ☉}). The late turn-on time of the super-soft component yields a large nova ejecta mass (≳ 10{sup –5} M {sub ☉}), consistent with estimates at other wavelengths. The hard X-ray component is well fit by a ∼1 keV thermal plasma, and is attributed to shocks internal to the 2011 nova ejecta. The presence of a strong oxygen line in this thermal plasma on Day 194 requires a significantly super-solar abundance of oxygen and implies that the ejecta are polluted by white dwarf material. The X-ray light curve can be explained by a dual-phase ejection, with a significant delay between the first and second ejection phases, and the second ejection finally released two months after outburst. A delayed ejection is consistent with optical and radio observations of T Pyx, but the physical mechanism producing such a delay remains a mystery.« less

Optically controlled phased array antenna concepts using GaAs monolithic microwave integrated circuits

NASA Technical Reports Server (NTRS)

Kunath, R. R.; Bhasin, K. B.

1986-01-01

The desire for rapid beam reconfigurability and steering has led to the exploration of new techniques. Optical techniques have been suggested as potential candidates for implementing these needs. Candidates generally fall into one of two areas: those using fiber optic Beam Forming Networks (BFNs) and those using optically processed BFNs. Both techniques utilize GaAs Monolithic Microwave Integrated Circuits (MMICs) in the BFN, but the role of the MMIC for providing phase and amplitude variations is largely eliminated by some new optical processing techniques. This paper discusses these two types of optical BFN designs and provides conceptual designs of both systems.

A Hubble Space Telescope survey for novae in M87.I. light and color curves, spatial distributions, and the nova rate

DOE PAGES

Shara, Michael M.; Doyle, Trisha F.; Lauer, Tod R.; ...

2016-11-08

The Hubble Space Telescope has imaged the central part of M87 over a 10 week span, leading to the discovery of 32 classical novae (CNe) and nine fainter, likely very slow, and/or symbiotic novae. In this first paper of a series, we present the M87 nova finder charts, and the light and color curves of the novae. We demonstrate that the rise and decline times, and the colors of M87 novae are uncorrelated with each other and with position in the galaxy. The spatial distribution of the M87 novae follows the light of the galaxy, suggesting that novae accreted by M87 during cannibalistic episodes are well-mixed. Conservatively using only the 32 brightest CNe we derive a nova rate for M87:more » $${363}_{-45}^{+33}$$ novae yr –1. We also derive the luminosity-specific classical nova rate for this galaxy, which is $${7.88}_{-2.6}^{+2.3}\\,{\\mathrm{yr}}^{-1}/{10}^{10}\\,{L}_{\\odot }{,}_{K}$$. Both rates are 3–4 times higher than those reported for M87 in the past, and similarly higher than those reported for all other galaxies. As a result, we suggest that most previous ground-based surveys for novae in external galaxies, including M87, miss most faint, fast novae, and almost all slow novae near the centers of galaxies.« less

Collimation and Asymmetry of the Hot Blast Wave from the Recurrent Nova V745 Sco

NASA Astrophysics Data System (ADS)

Drake, Jeremy J.; Delgado, Laura; Laming, J. Martin; Starrfield, Sumner; Kashyap, Vinay; Orlando, Salvatore; Page, Kim L.; Hernanz, M.; Ness, J.-U.; Gehrz, R. D.; van Rossum, Daan; Woodward, Charles E.

2016-07-01

The recurrent symbiotic nova V745 Sco exploded on 2014 February 6 and was observed on February 22 and 23 by the Chandra X-ray Observatory Transmission Grating Spectrometers. By that time the supersoft source phase had already ended, and Chandra spectra are consistent with emission from a hot, shock-heated circumstellar medium with temperatures exceeding 107 K. X-ray line profiles are more sharply peaked than expected for a spherically symmetric blast wave, with a full width at zero intensity of approximately 2400 km s-1, an FWHM of 1200 ± 30 km s-1, and an average net blueshift of 165 ± 10 km s-1. The red wings of lines are increasingly absorbed toward longer wavelengths by material within the remnant. We conclude that the blast wave was sculpted by an aspherical circumstellar medium in which an equatorial density enhancement plays a role, as in earlier symbiotic nova explosions. Expansion of the dominant X-ray-emitting material is aligned close to the plane of the sky and is most consistent with an orbit seen close to face-on. Comparison of an analytical blast wave model with the X-ray spectra, Swift observations, and near-infrared line widths indicates that the explosion energy was approximately 1043 erg and confirms an ejected mass of approximately 10-7 M ⊙. The total mass lost is an order of magnitude lower than the accreted mass required to have initiated the explosion, indicating that the white dwarf is gaining mass and is a Type Ia supernova progenitor candidate.

Thermoelectric Transport in Surface- and Antimony-Doped Bismuth Telluride Nanoplates

DTIC Science & Technology

2016-07-25

0.50) using two different electron microscopes with two different high sensitivity energy dispersive x-ray spectroscopy (EDS) detectors (FEI Nova...Figure 1(b)) using an electrochemically sharpened probe. Transfer was performed in ambient conditions under an optical microscope . Samples were then...attributed to additional alloy scattering in the (Bi1−xSbx)2Te3 samples studied here. Additionally, the room temperature κlattice for bulk compounds Reuse of

Recurrent novae

NASA Technical Reports Server (NTRS)

Hack, Margherita; Selvelli, Pierluigi

1993-01-01

Recurrent novae seem to be a rather inhomogeneous group: T CrB is a binary with a M III companion; U Sco probably has a late dwarf as companion. Three are fast novae; two are slow novae. Some of them appear to have normal chemical composition; others may present He and CNO excess. Some present a mass-loss that is lower by two orders of magnitude than classical novae. However, our sample is too small for saying whether there are several classes of recurrent novae, which may be related to the various classes of classical novae, or whether the low mass-loss is a general property of the class or just a peculiarity of one member of the larger class of classical novae and recurrent novae.

The awakening of a classical nova from hibernation.

PubMed

Mróz, Przemek; Udalski, Andrzej; Pietrukowicz, Paweł; Szymański, Michał K; Soszyński, Igor; Wyrzykowski, Łukasz; Poleski, Radosław; Kozłowski, Szymon; Skowron, Jan; Ulaczyk, Krzysztof; Skowron, Dorota; Pawlak, Michał

2016-09-29

Cataclysmic variable stars-novae, dwarf novae, and nova-likes-are close binary systems consisting of a white dwarf star (the primary) that is accreting matter from a low-mass companion star (the secondary). From time to time such systems undergo large-amplitude brightenings. The most spectacular eruptions, with a ten-thousandfold increase in brightness, occur in classical novae and are caused by a thermonuclear runaway on the surface of the white dwarf. Such eruptions are thought to recur on timescales of ten thousand to a million years. In between, the system's properties depend primarily on the mass-transfer rate: if it is lower than a billionth of a solar mass per year, the accretion becomes unstable and the matter is dumped onto the white dwarf during quasi-periodic dwarf nova outbursts. The hibernation hypothesis predicts that nova eruptions strongly affect the mass-transfer rate in the binary, keeping it high for centuries after the event. Subsequently, the mass-transfer rate should significantly decrease for a thousand to a million years, starting the hibernation phase. After that the nova awakes again-with accretion returning to the pre-eruption level and leading to a new nova explosion. The hibernation model predicts cyclical evolution of cataclysmic variables through phases of high and low mass-transfer. The theory gained some support from the discovery of ancient nova shells around the dwarf novae Z Camelopardalis and AT Cancri, but direct evidence for considerable mass-transfer changes prior, during and after nova eruptions has not hitherto been found. Here we report long-term observations of the classical nova V1213 Cen (Nova Centauri 2009) covering its pre- and post-eruption phases and precisely documenting its evolution. Within the six years before the explosion, the system revealed dwarf nova outbursts indicative of a low mass-transfer rate. The post-nova is two orders of magnitude brighter than the pre-nova at minimum light with no trace of dwarf nova behaviour, implying that the mass-transfer rate increased considerably as a result of the nova explosion.

The Masses and Accretion Rates of White Dwarfs in Classical and Recurrent Novae

NASA Astrophysics Data System (ADS)

Shara, Michael M.; Prialnik, Dina; Hillman, Yael; Kovetz, Attay

2018-06-01

Models have long predicted that the frequency-averaged masses of white dwarfs (WDs) in Galactic classical novae are twice as large as those of field WDs. Only a handful of dynamically well-determined nova WDs masses have been published, leaving the theoretical predictions poorly tested. The recurrence time distributions and mass accretion rate distributions of novae are even more poorly known. To address these deficiencies, we have combined our extensive simulations of nova eruptions with the Strope et al. and Schaefer databases of outburst characteristics of Galactic classical and recurrent novae (RNe) to determine the masses of 92 WDs in novae. We find that the mean mass (frequency-averaged mean mass) of 82 Galactic classical novae is 1.06 (1.13) M ⊙, while the mean mass of 10 RNe is 1.31 M ⊙. These masses, and the observed nova outburst amplitude and decline time distributions allow us to determine the long-term mass accretion rate distribution of classical novae. Remarkably, that value is just 1.3 × 10‑10 M ⊙ yr‑1, which is an order of magnitude smaller than that of cataclysmic binaries in the decades before and after classical nova eruptions. This predicts that old novae become low-mass transfer rate systems, and hence dwarf novae, for most of the time between nova eruptions. We determine the mass accretion rates of each of the 10 known Galactic recurrent nova, finding them to be in the range of 10‑7–10‑8 M ⊙ yr‑1. We are able to predict the recurrence time distribution of novae and compare it with the predictions of population synthesis models.

A Hubble Space Telescope Survey for Novae in M87. I. Light and Color Curves, Spatial Distributions, and the Nova Rate

NASA Astrophysics Data System (ADS)

Shara, Michael M.; Doyle, Trisha F.; Lauer, Tod R.; Zurek, David; Neill, J. D.; Madrid, Juan P.; Mikołajewska, Joanna; Welch, D. L.; Baltz, Edward A.

2016-11-01

The Hubble Space Telescope has imaged the central part of M87 over a 10 week span, leading to the discovery of 32 classical novae (CNe) and nine fainter, likely very slow, and/or symbiotic novae. In this first paper of a series, we present the M87 nova finder charts, and the light and color curves of the novae. We demonstrate that the rise and decline times, and the colors of M87 novae are uncorrelated with each other and with position in the galaxy. The spatial distribution of the M87 novae follows the light of the galaxy, suggesting that novae accreted by M87 during cannibalistic episodes are well-mixed. Conservatively using only the 32 brightest CNe we derive a nova rate for M87: {363}-45+33 novae yr‑1. We also derive the luminosity-specific classical nova rate for this galaxy, which is {7.88}-2.6+2.3 {yr}}-1/{10}10 {L}ȯ {,}K. Both rates are 3–4 times higher than those reported for M87 in the past, and similarly higher than those reported for all other galaxies. We suggest that most previous ground-based surveys for novae in external galaxies, including M87, miss most faint, fast novae, and almost all slow novae near the centers of galaxies. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

Distant Cluster Hunting. II; A Comparison of X-Ray and Optical Cluster Detection Techniques and Catalogs from the ROSAT Optical X-Ray Survey

NASA Technical Reports Server (NTRS)

Donahue, Megan; Scharf, Caleb A.; Mack, Jennifer; Lee, Y. Paul; Postman, Marc; Rosait, Piero; Dickinson, Mark; Voit, G. Mark; Stocke, John T.

2002-01-01

We present and analyze the optical and X-ray catalogs of moderate-redshift cluster candidates from the ROSA TOptical X-Ray Survey, or ROXS. The survey covers the sky area contained in the fields of view of 23 deep archival ROSA T PSPC pointings, 4.8 square degrees. The cross-correlated cluster catalogs were con- structed by comparing two independent catalogs extracted from the optical and X-ray bandpasses, using a matched-filter technique for the optical data and a wavelet technique for the X-ray data. We cross-identified cluster candidates in each catalog. As reported in Paper 1, the matched-filter technique found optical counter- parts for at least 60% (26 out of 43) of the X-ray cluster candidates; the estimated redshifts from the matched filter algorithm agree with at least 7 of 1 1 spectroscopic confirmations (Az 5 0.10). The matched filter technique. with an imaging sensitivity of ml N 23, identified approximately 3 times the number of candidates (155 candidates, 142 with a detection confidence >3 u) found in the X-ray survey of nearly the same area. There are 57 X-ray candidates, 43 of which are unobscured by scattered light or bright stars in the optical images. Twenty-six of these have fairly secure optical counterparts. We find that the matched filter algorithm, when applied to images with galaxy flux sensitivities of mI N 23, is fairly well-matched to discovering z 5 1 clusters detected by wavelets in ROSAT PSPC exposures of 8000-60,000 s. The difference in the spurious fractions between the optical and X-ray (30%) and IO%, respectively) cannot account for the difference in source number. In Paper I, we compared the optical and X-ray cluster luminosity functions and we found that the luminosity functions are consistent if the relationship between X-ray and optical luminosities is steep (Lx o( L&f). Here, in Paper 11, we present the cluster catalogs and a numerical simulation of the ROXS. We also present color-magnitude plots for several of the cluster candidates, and examine the prominence of the red sequence in each. We find that the X-ray clusters in our survey do not all have a prominent red sequence. We conclude that while the red sequence may be a distinct feature in the color-magnitude plots for virialized massive clusters, it may be less distinct in lower mass clusters of galaxies at even moderate redshifts. Multiple, complementary methods of selecting and defining clusters may be essential, particularly at high redshift where all methods start to run into completeness limits, incomplete understanding of physical evolution, and projection effects.

The Galactic Nova Rate Revisited

NASA Astrophysics Data System (ADS)

Shafter, A. W.

2017-01-01

Despite its fundamental importance, a reliable estimate of the Galactic nova rate has remained elusive. Here, the overall Galactic nova rate is estimated by extrapolating the observed rate for novae reaching m≤slant 2 to include the entire Galaxy using a two component disk plus bulge model for the distribution of stars in the Milky Way. The present analysis improves on previous work by considering important corrections for incompleteness in the observed rate of bright novae and by employing a Monte Carlo analysis to better estimate the uncertainty in the derived nova rates. Several models are considered to account for differences in the assumed properties of bulge and disk nova populations and in the absolute magnitude distribution. The simplest models, which assume uniform properties between bulge and disk novae, predict Galactic nova rates of ˜50 to in excess of 100 per year, depending on the assumed incompleteness at bright magnitudes. Models where the disk novae are assumed to be more luminous than bulge novae are explored, and predict nova rates up to 30% lower, in the range of ˜35 to ˜75 per year. An average of the most plausible models yields a rate of {50}-23+31 yr-1, which is arguably the best estimate currently available for the nova rate in the Galaxy. Virtually all models produce rates that represent significant increases over recent estimates, and bring the Galactic nova rate into better agreement with that expected based on comparison with the latest results from extragalactic surveys.

ON POTASSIUM AND OTHER ABUNDANCE ANOMALIES OF RED GIANTS IN NGC 2419

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iliadis, C.; Karakas, A. I.; Prantzos, N.

2016-02-10

Globular clusters are of paramount importance for testing theories of stellar evolution and early galaxy formation. Strong evidence for multiple populations of stars in globular clusters derives from observed abundance anomalies. A puzzling example is the recently detected Mg–K anticorrelation in NGC 2419. We perform Monte Carlo nuclear reaction network calculations to constrain the temperature–density conditions that gave rise to the elemental abundances observed in this elusive cluster. We find a correlation between stellar temperature and density values that provide a satisfactory match between simulated and observed abundances in NGC 2419 for all relevant elements (Mg, Si, K, Ca, Sc,more » Ti, and V). Except at the highest densities (ρ ≳ 10{sup 8} g cm{sup −3}), the acceptable conditions range from ≈100 MK at ≈10{sup 8} g cm{sup −3} to ≈200 MK at ≈10{sup −4} g cm{sup −3}. This result accounts for uncertainties in nuclear reaction rates and variations in the assumed initial composition. We review hydrogen-burning sites and find that low-mass stars, asymptotic giant branch (AGB) stars, massive stars, or supermassive stars cannot account for the observed abundance anomalies in NGC 2419. Super-AGB stars could be viable candidates for the polluter stars if stellar model parameters can be fine-tuned to produce higher temperatures. Novae, involving either CO or ONe white dwarfs, could be interesting polluter candidates, but a current lack of low-metallicity nova models precludes firmer conclusions. We also discuss whether additional constraints for the first-generation polluters can be obtained by future measurements of oxygen, or by evolving models of second-generation low-mass stars with a non-canonical initial composition.« less

Proper-motion age dating of the progeny of Nova Scorpii AD 1437.

PubMed

Shara, M M; Iłkiewicz, K; Mikołajewska, J; Pagnotta, A; Bode, M F; Crause, L A; Drozd, K; Faherty, J; Fuentes-Morales, I; Grindlay, J E; Moffat, A F J; Pretorius, M L; Schmidtobreick, L; Stephenson, F R; Tappert, C; Zurek, D

2017-08-30

'Cataclysmic variables' are binary star systems in which one star of the pair is a white dwarf, and which often generate bright and energetic stellar outbursts. Classical novae are one type of outburst: when the white dwarf accretes enough matter from its companion, the resulting hydrogen-rich atmospheric envelope can host a runaway thermonuclear reaction that generates a rapid brightening. Achieving peak luminosities of up to one million times that of the Sun, all classical novae are recurrent, on timescales of months to millennia. During the century before and after an eruption, the 'novalike' binary systems that give rise to classical novae exhibit high rates of mass transfer to their white dwarfs. Another type of outburst is the dwarf nova: these occur in binaries that have stellar masses and periods indistinguishable from those of novalikes but much lower mass-transfer rates, when accretion-disk instabilities drop matter onto the white dwarfs. The co-existence at the same orbital period of novalike binaries and dwarf novae-which are identical but for their widely varying accretion rates-has been a longstanding puzzle. Here we report the recovery of the binary star underlying the classical nova eruption of 11 March AD 1437 (refs 12, 13), and independently confirm its age by proper-motion dating. We show that, almost 500 years after a classical-nova event, the system exhibited dwarf-nova eruptions. The three other oldest recovered classical novae display nova shells, but lack firm post-eruption ages, and are also dwarf novae at present. We conclude that many old novae become dwarf novae for part of the millennia between successive nova eruptions.

Novae as distance indicators

NASA Technical Reports Server (NTRS)

Ford, Holland C.; Ciardullo, Robin

1988-01-01

Nova shells are characteristically prolate with equatorial bands and polar caps. Failure to account for the geometry can lead to large errors in expansion parallaxes for individual novae. When simple prescriptions are used for deriving expansion parallaxes from an ensemble of randomly oriented prolate spheroids, the average distance will be too small by factors of 10 to 15 percent. The absolute magnitudes of the novae will be underestimated and the resulting distance scale will be too small by the same factors. If observations of partially resolved nova shells select for large inclinations, the systematic error in the resulting distance scale could easily be 20 to 30 percent. Extinction by dust in the bulge of M31 may broaden and shift the intrinsic distribution of maximum nova magnitudes versus decay rates. We investigated this possibility by projecting Arp's and Rosino's novae onto a composite B - 6200A color map of M31's bulge. Thirty two of the 86 novae projected onto a smooth background with no underlying structure due to the presence of a dust cloud along the line of sight. The distribution of maximum magnitudes versus fade rates for these unreddened novae is indistinguishable from the distribution for the entire set of novae. It is concluded that novae suffer very little extinction from the filamentary and patchy distribution of dust seen in the bulge of M31. Time average B and H alpha nova luminosity functions are potentially powerful new ways to use novae as standard candles. Modern CCD observations and the photographic light curves of M31 novae found during the last 60 years were analyzed to show that these functions are power laws. Consequently, unless the eruption times for novae are known, the data cannot be used to obtain distances.

Classical novae and recurrent novae: General properties

NASA Technical Reports Server (NTRS)

Hack, Margherita; Selvelli, Pierluigi; Duerbeck, Hilmar W.

1993-01-01

We describe the observable characteristics of classical novae and recurrent novae obtained by different techniques (photometry, spectroscopy, and imaging) in all the available spectral ranges. We consider the three stages in the life of a nova: quiescence (pre- and post-outburst), outburst, final decline and nebular phase. We describe the photometric properties during the quiescent phase. We describe the photometric properties during outburst, the classification according the rate of decline (magnitudes per day), which permits us to define very fast, fast, intermediate, slow, and very slow novae and the correlation between luminosity and speed class. We report the scanty data on the spectra of the few known prenovae and those on the spectra of old novae and those of dwarf novae and nova-like, which, however, are almost undistinguishable. We describe the typical spectra appearing from the beginning of the outburst, just before maximum, up to the nebular phase and the correlation between spectral type at maximum, expansional velocity, and speed class of the nova. We report the existing infrared observations, which permit us to explain some of the characteristics of the outburst light curve, and give evidence of the formation of a dust shell in slow and intermediate novae (with the important exception of the very slow nova HR Del 1967) and its absence or quasi-absence in fast novae. The ultraviolet and X-ray observations are described. The X ray observations of novae, mainly from the two satellites EINSTEIN and EXOSAT, are reported. Observations of the final decline and of the envelopes appearing several months after outburst are also reported.

A Classical Nova Explosion in a Binary System with B[e] Star

NASA Astrophysics Data System (ADS)

Filippova, E.; Revnivtsev, M.; Lutovinov, A.

2011-09-01

The description of a thermonuclear runaway on a white dwarf, which causes a Classical Nova (CN) explosion, has several uncertainties. Observational tests of models are challenging because the majority of CNe are observed in optical and NIR spectral bands days after the onset of the explosion. We propose to use the properties of the X-ray emission of CNe for these tests. We have developed a model for the 1998 CN explosion in the binary system CI Cam. According to the adopted model the stellar wind from the optical component (a B[e] star), heated by a strong shock wave that was produced when matter was ejected from the white dwarf as the result of a thermonuclear explosion on its surface, is the source of X-ray emission in the standard X-ray band (˜ 2 - 10 keV). We use this model to explain the behaviour of the X-ray luminosity and of the mean temperature of the heated material during the explosion, and obtain velocity and mass estimates of the ejected matter from the WD surface. Discrepancies between model and observations, for example the slower decline of the theoretical luminosity compared to the observed one, are likely caused by the rough assumption of spherical symmetry. Using 3D calculations we find possible density perturbations (accretion wakes) that can reconcile theory with observations.

The nova-like cataclysmic variable star: KUV 0859+415

NASA Astrophysics Data System (ADS)

Grauer, Albert D.; Ringwald, F. A.; Wegner, Gary; Liebert, James; Schmidt, Gary D.; Green, Richard F.

1994-07-01

KUV 0859+415 has been found to be an eclipsing, nova-like cataclysmic variable with an orbital period of 3 h and 40 min. We find that it differs from other eclipsing systems of similar period (sometimes called the SW Sex stars) in several important respects. First, the eclipses are shallow, V-shaped dips, suggesting that the inclination angle is relatively low. Also, while the excitation of the emission lines are relatively high (He II comparable to H-beta), they are relatively weak compared to the continuum. The high Balmer lines have broad absorption wings, characteristic of an optically thick accretion disk. Yet there is evidence for a 'hot spot' in the system, which reaches peak brightness near phase 0.9 before the eclipse. Perhaps the most puzzling property of this system is that the H-alpha emission line radial velocity leads rather than lags the expected position for the location of the accretion disk. We present briefly a phenomenological model for the system which has a hot spot located at the normal location for the accretion stream to first impact the disk and is the source of excess optical continuum. However, the velocity curve of the emission lines requires us to conclude that the bulk of this radiation forms on the opposite side of the disk. This also explains the fact that the peak equivalent widths of H-alpha occur at phases 0.4-0.5.

A statistical analysis of IUE spectra of dwarf novae and nova-like stars

NASA Technical Reports Server (NTRS)

Ladous, Constanze

1990-01-01

First results of a statistical analysis of the IUE International Ultraviolet Explorer archive on dwarf novae and nova like stars are presented. The archive contains approximately 2000 low resolution spectra of somewhat over 100 dwarf novae and nova like stars. Many of these were looked at individually, but so far the collective information content of this set of data has not been explored. The first results of work are reported.

Gamma Rays from Classical Novae

NASA Technical Reports Server (NTRS)

1997-01-01

NASA at the University of Chicago, provided support for a program of theoretical research into the nature of the thermonuclear outbursts of the classical novae and their implications for gamma ray astronomy. In particular, problems which have been addressed include the role of convection in the earliest stages of nova runaway, the influence of opacity on the characteristics of novae, and the nucleosynthesis expected to accompany nova outbursts on massive Oxygen-Neon-Magnesium (ONeMg) white dwarfs. In the following report, I will identify several critical projects on which considerable progress has been achieved and provide brief summaries of the results obtained:(1) two dimensional simulation of nova runaway; (2) nucleosynthesis of nova modeling; and (3) a quasi-analytic study of nucleosynthesis in ONeMg novae.

The Spectroscopic Evolution of the Symbiotic-like Recurrent Nova V407 Cygni During Its 2010 Outburst. 2. The Circumstellar Environment and the Aftermath

NASA Technical Reports Server (NTRS)

Shore, S. N.; Wahlgren, G. M.; Augusteijn, T.; Liimets, T.; Koubsky, P.; Slechta, M.; Votruba, V.

2011-01-01

The nova outburst of V407 Cyg in 2010 Mar. 10 was the first observed for this star but its close resemblance to the well known symbiotic-like recurrent nova RS Oph suggests that it is also a member of this rare type of Galactic novae. The nova was the first detected at gamma-ray energies and is the first known nova explosion for this system. The extensive multiwavelength coverage of this outburst makes it an ideal comparison with the few other outbursts known for similar systems. We extend our previous analysis of the Mira and the expanding shock from the explosion to detail the time development of the photoionized Mira wind, circumstellar medium, and shocked circumstellar environment to derive their physical parameters and how they relate to large scale structure of the environment, extending the previous coverage to more than 500 days after outburst. We use optical spectra obtained at high resolution with the Nordic Optical Telescope (NOT) (R approx. =.45000 to 65000) and medium resolution Ondrejov Observatory (R approx. = 12000) data and compare the line variations with publicly available archival measurements at 30 GHz OVNR and at X-rays with Swift during the first four months of the outburst, through the end of the epoch of strong XR emission. We use nebular diagnostics and high resolution profile variations to derive the densities and locations of the extended emission. We find that the higher the ionization and/or the higher the excitation energy, the more closely the profiles resemble the He II/Ca V-type high velocity shock profile discussed in Paper I. This also accounts for the comparative development of the [N II] and [O III] isoelectronic transitions: the [O III] 4363A profile does not show the low velocity peaks while the excited [N II] 5754A does. If nitrogen is mainly N(+3) or higher in the shock, the upper state of the [N II] nebular lines will contribute but if the oxygen is O(+2) then this line is formed by recombination, masking the nebular contributor, and the lower states are collisionally quenched but emit from the low density surroundings. Absorption lines of Fe-peak ions formed in the Mira wind were visible as P Cyg profiles at low velocity before Day 69, around the time of the X-ray peak and we identified many absorption transitions without accompanying emission for metal lines. The H Balmer lines showed strong P Cyg absorption troughs that weakened during the 2010 observing period, through Day 128. The Fe-peak line profiles and flux variations were different for permitted and forbidden transitions: the E1 transitions were not visible after Day 128 but had shown a narrow peak superimposed on an extended (200 km/s) blue wing, while the M1 and E2 transitions persisted to Day 529, the last observation, and showed extended redshifted wings up of the same velocity. We distinguish the components from the shock, the photoionized environment, and the chromosphere and inner Mira wind using spectra taken more than one year after outburst. The multiple shells and radiative excitation phenomenology are similar to those recently cited for GRBs and SNIa .

The spectroscopic evolution of novae in the bulge of M31 and a search for their possible origin in the M31 globular cluster system

NASA Astrophysics Data System (ADS)

Tomaney, Austin Bede

Results are presented from a three year (1987 to 1989) spectroscopic and photometric survey of novae in M3l's bulge, the first comprehensive study of novae outside the Galactic and Magellanic Cloud systems. Nine novae were detected and monitored and their spectra cover a range of outburst states from early decline to the early nebular phases. Broad agreement in spectral morphology and evolution is found with Galactic novae. Since Galactic novae are mainly disk objects, this indicates that novae outburst properties are not critically dependent on the metallicity of the progenitor population. However, in this sample, and in a sample of four M31 nova spectra taken in 1983, no fast, violent outbursts frequently associated with nova systems containing ONeMg white dwarfs were found, suggestive of a systematic difference between the observed proportion of such outbursts between Galactic and M31 bulge novae. Three novae in the sample were observed on succeeding nights during the transition phase of their evolution. Extraordinary variations in some nightly line strengths, particularly the N III lines, were discovered. It is argued that this variability reflects the deposition of drag energy by the secondary star during the common envelope phase of nova evolution and is indicative of a key phase in mass loss from nova systems. Observations include the spectroscopic coverage of an extremely slow nova from 1987 to l990, during the object's evolution in the nebula phase. This provided a unique opportunity to make the first detailed comparison of the evolution and properties of an extra galactic nova with those in our own Galaxy. The roughly solar abundances obtained are typical of similar slow Galactic novae. Further observations are also presented of a unique outburst in 1988 that was independently discovered and reported by Rich et al. These data confirm the inferences of other observers that the outburst differed markedly from that of a typical classical nova. Finally an extensive spectroscopic survey of the M31 globular cluster system was made in an effort to find evidence of a previously suggested enhanced nova rate in these objects. No outbursts were detected during an effective survey time of one year for the entire system.

Recent progress in understanding the eruptions of classical novae

NASA Technical Reports Server (NTRS)

Shara, Michael M.

1988-01-01

Dramatic progress has occurred in the last two decades in understanding the physical processes and events leading up to, and transpiring during the eruption of a classical nova. The mechanism whereby a white dwarf accreting hydrogen-rich matter from a low-mass main-sequence companion produces a nova eruption has been understood since 1970. The mass-transferring binary stellar configuration leads inexorably to thermonuclear runaways detected at distances of megaparsecs. Summarized here are the efforts of many researchers in understanding the physical processes which generate nova eruptions; the effects upon nova eruptions of different binary-system parameters (e.g., chemical composition or mass of the white dwarf, different mass accretion rates); the possible metamorphosis from dwarf to classical novae and back again; and observational diagnostics of novae, including x ray and gamma ray emission, and the characteristics and distributions of novae in globular clusters and in extragalactic systems. While the thermonuclear-runaway model remains the successful cornerstone of nova simulation, it is now clear that a wide variety of physical processes, and three-dimensional hydrodynamic simulations, will be needed to explain the rich spectrum of behavior observed in erupting novae.

Hunting Elusive SPRITEs with Spitzer

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-05-01

In recent years, astronomers have developed many wide-field imaging surveys in which the same targets are observed again and again. This new form of observing has allowed us to discover optical and radio transients explosive or irregular events with durations ranging from seconds to years. The dynamic infrared sky, however, has remained largely unexplored until now.Infrared ExplorationExample of a transient: SPIRITS 14ajc was visible when imaged by SPIRITS in 2014 (left) but it wasnt there during previous imaging between 2004 and 2008 (right). The bottom frame shows the difference between the two images. [Adapted from Kasliwal et al. 2017]Why hunt for infrared transients? Optical wavelengths dont allow us to observe events that are obscured, such that their own structure or their surroundings hide them from our view. Both supernovae and luminous red novae (associated with stellar mergers) are discoverable as infrared transients, and there may well be new types of transients in infrared that we havent seen before!To explore this uncharted territory, a team of scientists developed SPIRITS, the Spitzer Infrared Intensive Transients Survey. Begun in 2014, SPIRITS is a five-year long survey that uses the Spitzer Space Telescope to conduct a systematic search for mid-infrared transients in nearby galaxies.In a recent publication led by Mansi Kasliwal (Caltech and the Carnegie Institution for Science), the SPIRITS team has now detailed how their survey works and what theyve discovered in its first year.The light curves of SPRITEs (red stars) lie in the mid-infared luminosity gap between novae (orange) and supernovae (blue). [Kasliwal et al. 2017]Mystery TransientsKasliwal and collaborators used Spitzer to monitor 190 nearby galaxies. In SPIRITS first year, they found over 1958 variable stars and 43 infrared transient sources. Of these 43 transients, 21 were known supernovae, 4 were in the luminosity range of novae, and 4 had optical counterparts. The remaining 14 events were designated eSPecially Red Intermediate-luminosity Transient Events, or SPRITEs.SPRITEs are unusual infrared transients that lie in the luminosity gap between novae and supernovae, and they have no optical counterparts. They all occur in star-forming galaxies.Search for the CauseWhats the physical origin of these phenomena? The authors explore a number of possible sources, including obscured supernovae, stellar mergers with dusty winds, collapse of extreme stars, or even weak shocks in failed supernovae.Spitzer image of M83, one of the closest barred spiral galaxies in the sky. SPIRITS 14ajc was discovered in one of M83s spiral arms. [NASA/JPL-Caltech]In one case, SPIRITS 14ajc, the SPRITEs spectrum shows signs of excited molecular hydrogen lines, which are indicative of a shock. Based on the data, Kasliwal and collaborators propose that the shock might have been driven into a molecular cloud after it was triggered by the decay of a system of massive stars that either passed closely or collided and merged.The other SPRITEs may all have different origins, however, and in general the infrared photometric data isnt sufficient to identify which model fits each transient. Future technology, like spectroscopy with the James Webb Space Telescope, may help us to better understand the origins of these elusive transients, though. And future surveying with projects like SPIRITS will help us to discover more SPRITE-like events, expanding our understanding of the dynamic infrared sky.CitationMansi M. Kasliwal et al 2017 ApJ 839 88. doi:10.3847/1538-4357/aa6978

Nova V2214 Ophiuchi 1988 - A magnetic nova inside the period gap

NASA Technical Reports Server (NTRS)

Baptista, R.; Jablonski, F. J.; Cieslinski, D.; Steiner, J. E.

1993-01-01

The discovery of a coherent photometric modulation in Nova Oph 1988 with period 0.117515 +/- 0.000002 d, which is associated with the orbital period of the underlying binary, is reported. On the basis of photometric observations, it is concluded that Nova V2214 Oph 1988 is a magnetic nova with an orbital period inside the period gap. The inclusion of this system in the statistics of novae suggests that there is no period gap for novae and that there is a clear correlation between the occurrence of novae with short orbital periods and the presence of magnetic white dwarfs. It is suggested that funneling of the accretion flow onto the magnetic poles favors the conditions for a thermonuclear runaway, increasing the frequency of eruptions for magnetic systems.

X-ray nova and LMXB V404 Cyg in rare outburst

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2015-06-01

V404 Cyg, an X-ray nova and a low mass X-ray binary (LMXB) with black hole component, is undergoing its first reported X-ray and optical outburst since 1989. Large scale, rapid variations are being reported in wavelengths from X-ray to radio by professional and amateur astronomers worldwide. Satellite and ground-based observations have been and are continuing to be made by many members of the professional community, including S. D. Barthelmy et al. (GCN Circular 17929, 15 June 2015, Swift BAT initial detection); H. Negoro et al. (ATel #7646, 17 Jun 2015); E. Kuulkers et al. (ATel #7647, 17 June 2015, Swift observations); K. Gazeas et al. (ATel #7650, 17 June 2015, optical photometry); R. M. Wagner et al. (ATel #7655, 18 June, optical spectroscopy); K. Mooley et al. (ATel #7658, 18 June, radio observations). T. Munoz-Darias et al. report P Cyg profiles were seen on 18 Jun 2015 (ATel #7659). They note that P-Cyg profiles were also observed during the 1989 outburst (Casares et al. 1991, MNRAS, 250, 712), and that V404 Cyg is so far the only black hole X-ray transient that has shown this phenomenology. Observations in all bands are requested. Filtered observations are preferred. Please use a cadence as high as possible while obtaining a suitable s/n. If spectroscopy is possible with your equipment, it is requested. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. Precise observing instructions and other details are given in the full Alert Notice.

A Hubble Space Telescope survey for Novae in M87. II. Snuffing out the maximum magnitude–rate of decline relation for novae as a non-standard candle, and a prediction of the existence of ultrafast novae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shara, Michael M.; Doyle, Trisha; Lauer, Tod R.

The extensive grid of numerical simulations of nova eruptions first predicted that some classical novae might significantly deviate from the Maximum Magnitude–Rate of Decline (MMRD) relation, which purports to characterize novae as standard candles. Kasliwal et al. have announced the observational detection of a new class of faint, fast classical novae in the Andromeda galaxy. These objects deviate strongly from the MMRD relationship, as predicted by Yaron et al. Recently, Shara et al. reported the first detections of faint, fast novae in M87. These previously overlooked objects are as common in the giant elliptical galaxy M87 as they are inmore » the giant spiral M31; they comprise about 40% of all classical nova eruptions and greatly increase the observational scatter in the MMRD relation. We use the extensive grid of the nova simulations of Yaron et al. to identify the underlying causes of the existence of faint, fast novae. These are systems that have accreted, and can thus eject, only very low-mass envelopes, of the order of 10 –7–10 –8 M ⊙, on massive white dwarfs. Such binaries include, but are not limited to, the recurrent novae. As a result, these same models predict the existence of ultrafast novae that display decline times, t 2, to be as short as five hours. We outline a strategy for their future detection.« less

A Hubble Space Telescope Survey for Novae in M87. II. Snuffing out the Maximum Magnitude–Rate of Decline Relation for Novae as a Non-standard Candle, and a Prediction of the Existence of Ultrafast Novae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shara, Michael M.; Doyle, Trisha; Zurek, David

The extensive grid of numerical simulations of nova eruptions from the work of Yaron et al. first predicted that some classical novae might significantly deviate from the Maximum Magnitude–Rate of Decline (MMRD) relation, which purports to characterize novae as standard candles. Kasliwal et al. have announced the observational detection of a new class of faint, fast classical novae in the Andromeda galaxy. These objects deviate strongly from the MMRD relationship, as predicted by Yaron et al. Recently, Shara et al. reported the first detections of faint, fast novae in M87. These previously overlooked objects are as common in the giantmore » elliptical galaxy M87 as they are in the giant spiral M31; they comprise about 40% of all classical nova eruptions and greatly increase the observational scatter in the MMRD relation. We use the extensive grid of the nova simulations of Yaron et al. to identify the underlying causes of the existence of faint, fast novae. These are systems that have accreted, and can thus eject, only very low-mass envelopes, of the order of 10{sup −7}–10{sup −8} M {sub ⊙}, on massive white dwarfs. Such binaries include, but are not limited to, the recurrent novae. These same models predict the existence of ultrafast novae that display decline times, t {sub 2,} to be as short as five hours. We outline a strategy for their future detection.« less

A Hubble Space Telescope survey for Novae in M87. II. Snuffing out the maximum magnitude–rate of decline relation for novae as a non-standard candle, and a prediction of the existence of ultrafast novae

DOE PAGES

Shara, Michael M.; Doyle, Trisha; Lauer, Tod R.; ...

2017-04-20

The extensive grid of numerical simulations of nova eruptions first predicted that some classical novae might significantly deviate from the Maximum Magnitude–Rate of Decline (MMRD) relation, which purports to characterize novae as standard candles. Kasliwal et al. have announced the observational detection of a new class of faint, fast classical novae in the Andromeda galaxy. These objects deviate strongly from the MMRD relationship, as predicted by Yaron et al. Recently, Shara et al. reported the first detections of faint, fast novae in M87. These previously overlooked objects are as common in the giant elliptical galaxy M87 as they are inmore » the giant spiral M31; they comprise about 40% of all classical nova eruptions and greatly increase the observational scatter in the MMRD relation. We use the extensive grid of the nova simulations of Yaron et al. to identify the underlying causes of the existence of faint, fast novae. These are systems that have accreted, and can thus eject, only very low-mass envelopes, of the order of 10 –7–10 –8 M ⊙, on massive white dwarfs. Such binaries include, but are not limited to, the recurrent novae. As a result, these same models predict the existence of ultrafast novae that display decline times, t 2, to be as short as five hours. We outline a strategy for their future detection.« less

The cataclysmic variables from the Palomar-Green survey

NASA Astrophysics Data System (ADS)

Ringwald, F. A.

1993-09-01

This thesis explores the cataclysmic variables (CVs) found by the Palomar-Green (PG) survey. This is the first compilation of a statistically complete sample of CVs found by ultraviolet color excess, and not outburst behavior. Blue and red follow-up spectrophotometry suggests that 22 of 68 objects classified originally as CVs are hot subdwarfs. Cool companions may be mimicking CVs' flat energy distributions, although the possibility remains that some are face-on CVs. Spectra taken with the International Ultraviolet Explorer satellite prove useful for distinguishing difficult cases. With the CV sample defined, the orbital periods for eleven systems are investigated with radial velocity studies. At 16th magnitude, CV number counts increase by 2.3 mag-1, although this may level off. The luminosity function is examined for the first time, and a trend toward higher space density at low luminosity is suspected. Outburst properties are compiled, and low-luminosity dwarf novae inflate the total space density to 6 x 10-6 pc-3. I describe all the PG CVs and candidate objects, and show spectra for most. This sample should be useful for population studies, such as measuring the space density with trigonometric parallaxes, or finding the fraction of eclipsing CVs. A new class of nova-likes, the SW Sextantis stars, is characterized by absorption events of the emission lines at spectroscopic phase 0.5, accompanied by large phase lags between the lightcurves and the radial velocity curves and strong high-excitation emission. There are at least six such CVs in this sample of 33, so this mysterious behavior must be common and not peculiar, as previously thought. Five of these six objects eclipse. Serendipitous results for individual CVs include finding low-frequency quasi-periodic variations in the radial velocity curve of the dwarf nova BZ Ursae Majoris. While erratic from epoch to epoch, these are too coherent to be pure noise. Another dwarf nova, HX Pegasi, is caught with time-resolved spectrophotometry on the rise to outburst. This is the second-ever such observation, and the first with red spectra. HX Pegasi is also confirmed as having a novel subdwarf-K red star.

Identificação de variáveis cataclísmicas eruptivas na direção do bojo galáctico e Nuvens de Magalhães usando dados do OGLE

NASA Astrophysics Data System (ADS)

Cieslinski, D.; Diaz, M. P.; Mennickent, R.; Pietrzyski, G.

2003-08-01

Na década de 90 iniciaram-se vários programas para a pesquisa de matéria escura na Galáxia usando o efeito de microlentes gravitacionais. Entre os projetos mais bem conhecidos podemos mencionar o OGLE (Optical Gravitational Lensing Experiment) e o MACHO (MAssive Compact Halo Objects). A estratégia usada por eles consiste em fazer fotometria de banda larga (normalmente B, R e I) de um grande número de estrelas (dezenas de milhões) tão freqüentemente quanto possí vel e por longos perí odos de tempo (anos). Uma tal sistemática de observação, além de descobrir inúmeras lentes gravitacionais, é também muito apropriada para a descoberta de estrelas variáveis. De fato, inúmeras novas variáveis de vários tipos foram descobertas como subproduto. Exemplos podem ser encontrados nos endereços http://bulge.princeton.edu/~ogle/ e http://wwwmacho.mcmaster.ca/. As variáveis cataclí smicas eruptivas (novas clássicas, novas recorrentes e novas anãs) são objetos que apresentam variabilidade de grande amplitude com escalas de tempo de dias a centenas de dias e, por esta razão, devem ter sido detectadas em grande número nestes "surveys". Para testar esta possibilidade nós procuramos nos dados do OGLE por tais sistemas e o presente trabalho mostra os resultados desta pesquisa. Os objetos foram selecionados entre as variáveis detectadas usando a amplitude de variação de brilho como critério principal. Este critério forneceu 13756 objetos, sendo 2169 na direção da Grande Nuvem de Magalhães, 1162 na direção da Pequena Nuvem de Magalhães e o restante na direção do Bojo Galáctico. A análise foi feita inspecionando-se visualmente cada curva de luz por erupções com as características acima mencionadas. Os resultados obtidos podem ser sumarizados como: descoberta de duas novas clássicas e 33 novas anãs. Além disso, pode-se mencionar a identificação de candidatas a outros tipos de variáveis como: estrelas simbióticas, RV Tauri, R Coronae Borealis, Miras, etc.

Cross Matching as Strategy to Find Radio Stars

NASA Astrophysics Data System (ADS)

Christian, Tiffany; Kimball, Amy

2018-01-01

Using cross-matching between the FIRST (20cm) and GPS1 (optical) catalogs, we identified possible radio star candidates. This is an extension of earlier work by Kimball et al. (2009), who sought to identify radiostar candidates by cross-matching the FIRST (radio)and SDSS (optical) catalogs, but did not include the consideration of stellar proper motions. We used proper motions from GPS1 to match with FIRST radio sources; the region of sky where they overlap contains ~900,000 FIRST sources and several million GPS1 sources. We used WISE near-infrared and PanSTARRS optical information to identify matches that have stellar colors. Our selection constraints identified 6 stars (spectroscopically confirmed) as radio star candidates. They are faint in the radio (<1 mJy) indicating we may be searching at the limits of the radio survey. Other candidates had no spectral confirmation or object type identification in SIMBAD, which would make them ideal for follow up radio observations. However, random analysis indicated that many other possible candidates were random associations, which may also be true for these 6 stars.

Survey of period variations of superhumps in SU UMa-type dwarf novae. VIII. The eighth year (2015-2016)

NASA Astrophysics Data System (ADS)

Kato, Taichi; Hambsch, Franz-Josef; Monard, Berto; Vanmunster, Tonny; Maeda, Yutaka; Miller, Ian; Itoh, Hiroshi; Kiyota, Seiichiro; Isogai, Keisuke; Kimura, Mariko; Imada, Akira; Tordai, Tamás; Akazawa, Hidehiko; Tanabe, Kenji; Otani, Noritoshi; Ogi, Minako; Ando, Kazuko; Takigawa, Naoki; Dubovsky, Pavol A.; Kudzej, Igor; Shugarov, Sergey Yu.; Katysheva, Natalia; Golysheva, Polina; Gladilina, Natalia; Chochol, Drahomir; Starr, Peter; Kasai, Kiyoshi; Pickard, Roger D.; de Miguel, Enrique; Kojiguchi, Naoto; Sugiura, Yuki; Fukushima, Daiki; Yamada, Eiji; Uto, Yusuke; Kamibetsunawa, Taku; Tatsumi, Taiki; Takeda, Nao; Matsumoto, Katsura; Cook, Lewis M.; Pavlenko, Elena P.; Babina, Julia V.; Pit, Nikolaj V.; Antonyuk, Oksana I.; Antonyuk, Kirill A.; Sosnovskij, Aleksei A.; Baklanov, Aleksei V.; Kafka, Stella; Stein, William; Voloshina, Irina B.; Ruiz, Javier; Sabo, Richard; Dvorak, Shawn; Stone, Geoff; Andreev, Maksim V.; Antipin, Sergey V.; Zubareva, Alexandra M.; Zaostrojnykh, Anna M.; Richmond, Michael; Shears, Jeremy; Dubois, Franky; Logie, Ludwig; Rau, Steve; Vanaverbeke, Siegfried; Simon, Andrei; Oksanen, Arto; Goff, William N.; Bolt, Greg; Dębski, Bartłomiej; Kochanek, Christopher S.; Shappee, Benjamin; Stanek, Krzysztof Z.; Prieto, José L.; Stubbings, Rod; Muyllaert, Eddy; Hiraga, Mitsutaka; Horie, Tsuneo; Schmeer, Patrick; Hirosawa, Kenji

2016-08-01

Continuing the project described by Kato et al. (2009, PASJ, 61, S395), we collected times of superhump maxima for 128 SU UMa-type dwarf novae observed mainly during the 2015-2016 season and characterized these objects. The data have improved the distribution of orbital periods, the relation between the orbital period and the variation of superhumps, and the relation between period variations and the rebrightening type in WZ Sge-type objects. Coupled with new measurements of mass ratios using growing stages of superhumps, we now have a clearer and statistically greatly improved evolutionary path near the terminal stage of evolution of cataclysmic variables. Three objects (V452 Cas, KK Tel, and ASASSN-15cl) appear to have slowly growing superhumps, which is proposed to reflect the slow growth of the 3 : 1 resonance near the stability border. ASASSN-15sl, ASASSN-15ux, SDSS J074859.55+312512.6, and CRTS J200331.3-284941 are newly identified eclipsing SU UMa-type (or WZ Sge-type) dwarf novae. ASASSN-15cy has a short (˜0.050 d) superhump period and appears to belong to EI Psc-type objects with compact secondaries having an evolved core. ASASSN-15gn, ASASSN-15hn, ASASSN-15kh, and ASASSN-16bu are candidate period bouncers with superhump periods longer than 0.06 d. We have newly obtained superhump periods for 79 objects and 13 orbital periods, including periods from early superhumps. In order that future observations will be more astrophysically beneficial and rewarding to observers, we propose guidelines on how to organize observations of various superoutbursts.

COLLIMATION AND ASYMMETRY OF THE HOT BLAST WAVE FROM THE RECURRENT NOVA V745 Sco

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drake, Jeremy J.; Kashyap, Vinay; Delgado, Laura

The recurrent symbiotic nova V745 Sco exploded on 2014 February 6 and was observed on February 22 and 23 by the Chandra X-ray Observatory Transmission Grating Spectrometers. By that time the supersoft source phase had already ended, and Chandra spectra are consistent with emission from a hot, shock-heated circumstellar medium with temperatures exceeding 10{sup 7} K. X-ray line profiles are more sharply peaked than expected for a spherically symmetric blast wave, with a full width at zero intensity of approximately 2400 km s{sup 1}, an FWHM of 1200 ± 30 km s{sup 1}, and an average net blueshift of 165more » ± 10 km s{sup 1}. The red wings of lines are increasingly absorbed toward longer wavelengths by material within the remnant. We conclude that the blast wave was sculpted by an aspherical circumstellar medium in which an equatorial density enhancement plays a role, as in earlier symbiotic nova explosions. Expansion of the dominant X-ray-emitting material is aligned close to the plane of the sky and is most consistent with an orbit seen close to face-on. Comparison of an analytical blast wave model with the X-ray spectra, Swift observations, and near-infrared line widths indicates that the explosion energy was approximately 10{sup 43} erg and confirms an ejected mass of approximately 10{sup 7} M {sub ⊙}. The total mass lost is an order of magnitude lower than the accreted mass required to have initiated the explosion, indicating that the white dwarf is gaining mass and is a Type Ia supernova progenitor candidate.« less

Electron Induced Scintillation Testing of Commercially Available Optical Fibers for Space Flight

NASA Technical Reports Server (NTRS)

Ott, Melanie N.

1999-01-01

A test to verify the performance of several commercial and military optical fibers available on the market today was conducted, via usage of an electron accelerator, to monitor radiation induced scintillation or luminescence. The test results showed that no significant effects could be detected with the PMT system used, above a noise floor of 50 photons/sec that were due to optical fiber scintillation. Although some data appeared to show events taking place, noise scan results have correlated these events to arcing inside the electron accelerator facility. This test was to simply characterize for space flight, which optical fiber candidates were the largest scintillators among the eighteen optical fiber candidates tested.

Infrared spectroscopy of the remnant of Nova Sco 2014: a symbiotic star with too little circumstellar matter to decelerate the ejecta

NASA Astrophysics Data System (ADS)

Munari, U.; Banerjee, D. P. K.

2018-03-01

Pre-outburst 2MASS and WISE photometry of Nova Sco 2014 (V1534 Sco) has suggested the presence of a cool giant at the location of the nova in the sky. The spectral evolution recorded for the nova did not, however, support a direct partnership because no flash-ionized wind and no deceleration of the ejecta were observed, contrary to the behaviour displayed by other novae which erupted within symbiotic binaries like V407 Cyg or RS Oph. We have therefore obtained 0.8-2.5 μm spectra of the remnant of Nova Sco 2014 in order to ascertain if a cool giant is indeed present and if it is physically associated with the nova. The spectrum shows the presence of a M6III giant, reddened by E(B - V) = 1.20, displaying the typical and narrow emission-line spectrum of a symbiotic star, including He I 1.0830 μm with a deep P-Cyg profile. This makes Nova Sco 2014 a new member of the exclusive club of novae that erupt within a symbiotic binary. Nova Sco 2014 shows that a nova erupting within a symbiotic binary does not always come with a deceleration of the ejecta, contrary to the common belief. Many other similar systems may lay hidden in past novae, especially in those that erupted prior to the release of the 2MASS all-sky infrared survey, which could be profitably cross-matched now against them.

Subaru Hyper Suprime-Cam Survey for an optical counterpart of GW170817

NASA Astrophysics Data System (ADS)

Tominaga, Nozomu; Tanaka, Masaomi; Morokuma, Tomoki; Utsumi, Yousuke; Yamaguchi, Masaki S.; Yasuda, Naoki; Tanaka, Masayuki; Yoshida, Michitoshi; Fujiyoshi, Takuya; Furusawa, Hisanori; Kawabata, Koji S.; Lee, Chien-Hsiu; Motohara, Kentaro; Ohsawa, Ryou; Ohta, Kouji; Terai, Tsuyoshi; Abe, Fumio; Aoki, Wako; Asakura, Yuichiro; Barway, Sudhanshu; Bond, Ian A.; Fujisawa, Kenta; Honda, Satoshi; Ioka, Kunihito; Itoh, Youichi; Kawai, Nobuyuki; Kim, Ji Hoon; Koshimoto, Naoki; Matsubayashi, Kazuya; Miyazaki, Shota; Saito, Tomoki; Sekiguchi, Yuichiro; Sumi, Takahiro; Tristram, Paul J.

2018-03-01

We perform a z-band survey for an optical counterpart of the binary neutron star coalescence GW170817 with Subaru/Hyper Suprime-Cam. Our untargeted transient search covers 23.6 deg2 corresponding to the 56.6% credible region of GW170817 and reaches the 50% completeness magnitude of 20.6 mag on average. As a result, we find 60 candidate extragalactic transients, including J-GEM17btc (also known as SSS17a/DLT17ck). While J-GEM17btc is associated with NGC 4993, which is firmly located inside the 3D skymap of GW170817, the other 59 candidates do not have distance information in the GLADE v2 catalog or NASA/IPAC Extragalactic Database. Among 59 of the candidates, 58 are located at the center of extended objects in the Pan-STARRS1 catalog, while one candidate has an offset. We present location, z-band apparent magnitude, and time variability of the candidates and evaluate the probabilities that they are located within the 3D skymap of GW170817. The probability for J-GEM17btc is 64%, which is much higher than for the other 59 candidates (9.3 × 10-3-2.1 × 10-1%). Furthermore, the possibility that at least one of the other 59 candidates is located within the 3D skymap is only 3.2%. Therefore, we conclude that J-GEM17btc is the most likely and distinguished candidate to be the optical counterpart of GW170817.

X-ray and optical observations of the ultrashort period dwarf nova SW Ursae Majoris - A likely new DQ Herculis star

NASA Technical Reports Server (NTRS)

Shafter, A. W.; Szkody, P.; Thorstensen, J. R.

1986-01-01

Time-resolved X-ray and optical photometric and optical spectroscopic observations of the ultrashort period cataclysmic variable SW UMa are reported. The spectroscopic observations reveal the presence of an s-wave component which is almost in phase with the extreme line wings and presumably the white dwarf. This very unusual phasing in conjunction with the available optical and X-ray data seems to indicate that a region of enhanced emission exists on the opposite side of the disk from the expected location of the hot spot. The photometric observations reveal the presence of a hump in the light curve occurring at an orbital phase which is consistent with the phase at which the region of enhanced line emission is most favorably seen. Changes in the hump amplitude are seen from night to night, and a 15.9 min periodicity is evident in the light curve. The optical and X-ray periodicities suggest that SW UMa is a member of the DQ Her class of cataclysmic variables.

Optical spectrophotometry of oscillations and flickering in AE Aquarii

NASA Technical Reports Server (NTRS)

Welsh, William F.; Horne, Keith; Oke, J. B.

1993-01-01

We observed rapid variations in the nova-like cataclysmic variable AE Aquarii for 1.7 hr with 4.3 s time resolution using the 30-channel (3227-10494 A) spectrophotometer on the Hale 5 m telescope. The 16.5 and 33.0 s oscillations show a featureless blue spectrum that can be represented by a blackbody with temperature and area much smaller than the accretion disk. Models consisting of the sum of a K star spectrum and a hydrogen slab in LTE at T = 6000-10,000 K can fit the spectrum of AE Aquarii reasonably well. The spectrum of a flare indicates optically thin gas with T = 8000-12,000 K. The energy released by the flare is large compared to typical stellar flares.

Ultraviolet observations of the symbiotic star AS 296

NASA Technical Reports Server (NTRS)

Gutierrez-Moreno, A.; Moreno, H.; Feibelman, W. A.

1992-01-01

AS 296 is a well-known S-type symbiotic star which underwent an optical outburst during 1988. In this paper, UV data based on IUE observations obtained both during the quiescent and outburst stages are presented and discussed, correlating them to observations made in the optical region. It is concluded that the object is a symbiotic nova, in which the outburst is due to a thermonuclear runaway produced in the hydrogen-burning shell of a white dwarf with M of about 0.5 solar masses, accreting from the late-type giant at a rate M(acc) of about 9.7 x 10 exp -9 solar mass/year. It is not possible to determine from the observations if the hydrogen flash is degenerate or nondegenerate.

A Hubble Space Telescope survey for novae in M87 - III. Are novae good standard candles 15 d after maximum brightness?

NASA Astrophysics Data System (ADS)

Shara, Michael M.; Doyle, Trisha F.; Pagnotta, Ashley; Garland, James T.; Lauer, Tod R.; Zurek, David; Baltz, Edward A.; Goerl, Ariel; Kovetz, Attay; Machac, Tamara; Madrid, Juan P.; Mikołajewska, Joanna; Neill, J. D.; Prialnik, Dina; Welch, D. L.; Yaron, Ofer

2018-02-01

Ten weeks of daily imaging of the giant elliptical galaxy M87 with the Hubble Space Telescope (HST) has yielded 41 nova light curves of unprecedented quality for extragalactic cataclysmic variables. We have recently used these light curves to demonstrate that the observational scatter in the so-called maximum-magnitude rate of decline (MMRD) relation for classical novae is so large as to render the nova-MMRD useless as a standard candle. Here, we demonstrate that a modified Buscombe-de Vaucouleurs hypothesis, namely that novae with decline times t2 > 10 d converge to nearly the same absolute magnitude about two weeks after maximum light in a giant elliptical galaxy, is supported by our M87 nova data. For 13 novae with daily sampled light curves, well determined times of maximum light in both the F606W and F814W filters, and decline times t2 > 10 d we find that M87 novae display M606W,15 = -6.37 ± 0.46 and M814W,15 = -6.11 ± 0.43. If very fast novae with decline times t2 < 10 d are excluded, the distances to novae in elliptical galaxies with stellar binary populations similar to those of M87 should be determinable with 1σ accuracies of ± 20 per cent with the above calibrations.

Finding the rarest objects in the universe: A new, efficient method for discovering BL Lacertae objects

NASA Technical Reports Server (NTRS)

Stocke, John; Perlman, Eric; Granados, Arno; Schachter, Jonathan; Elvis, Martin; Urry, Meg; Impey, Chris; Smith, Paul

1993-01-01

We present a new, efficient method for discovering new BL Lac Objects based upon the results of the Einstein Extended Medium Sensitivity Survey (EMSS). We have found that all x-ray selected BL Lacs are radio emitters, and further, that in a 'color-color' diagram (radio/optical and optical/x-ray) the BL Lac Objects occupy an area distinct from both radio loud quasars and the radio quiet QSOs and Seyferts which dominate x-ray selected samples. After obtaining radio counterparts via VLA 'snapshot' observations of a large sample of unidentified x-ray sources, the list of candidates is reduced. These candidates then can be confirmed with optical spectroscopy and/or polarimetry. Since greater than 70 percent of these sources are expected to be BL Lacs, the optical observations are very efficient. We have tested this method using unidentified sources found in the Einstein Slew Survey. The 162 Slew Survey x-ray source positions were observed with the VLA in a mixed B/C configuration at 6 cm resulting in 60 detections within 1.5 position error circle radii. These x-ray/optical/radio sources were then plotted, and 40 BL Lac candidates were identified. To date, 10 candidates have been spectroscopically observed resulting in 10 new BL Lac objects! Radio flux, optical magnitude, and polarization statistics (obtained in white light with the Steward Observatory 2.3 m CCD polarimeter) for each are given.

Nova Delphini 2013: Backyard Analysis of a Classical Nova

NASA Astrophysics Data System (ADS)

Reid, Piper

2014-01-01

On August 14, 2013, Nova Delphini was discovered by Koichi Itagaki. This nova erupted to a maximum brightness of magnitude 4.4 by August 16, 2013. The extraordinary brightness of this event has allowed many amateur astronomers to have the chance to study it. More than 750 amateur astronomers have contributed to the AAVSO photometry database of Nova Delphini.1 The amount and quality of spectroscopic data gathered is unprecedented as well, as over 700 individual spectra have been collected so far in the ARAS database.2 A nova is a class of variable star that undergoes a cataclysmic eruption, which can be observed through a sudden increase in brightness that declines over a series of months or years. At the center of a nova is an accreting white dwarf star which is collecting hydrogen from its surroundings. The accreting mass causes a nuclear reaction on the surface of the white dwarf and as the pressure increases the reaction becomes super-critical and a thermonuclear runaway is ignited causing the brightness increase as well as triggering the ejection of a shell of material form the star. The stages of a classical nova outburst are outlined along with techniques available to amateur astronomers for study of these phenomena. The author’s equipment and software setup are detailed. Results obtained using a low resolution grating, Schmidt-cassegrain telescope and CCD camera that were acquired while Nova Delphini was in the “fireball stage” 3 and subsequent “iron curtain phase”3 are compared and discussed. Results obtained using a high resolution spectroscope, Schmidt-cassegrain telescope and CCD camera that were acquired during the “lifting of the iron curtain phase”3 are also presented. References 1. Turner, Rebecca. “AAVSO - Nova Del 2013” 20 Aug 2013 Web. 8 Sep 2013 2. Tessier, Francois. “ARAS Spectral Database - Nova-Del-2013” 22 Sep 2013 Web. 22 Sep 2013 3. Shore, Steven N. “Spectroscopy of Novae - A User’s Manual” arXiv:1211.3176 [astro-ph.SR] 14 Nov 2012

On the implications of the period distributions of subclasses of cataclysmic variables

NASA Astrophysics Data System (ADS)

Verbunt, Frank

1997-09-01

The period distributions of dwarf novae and nova-like variables above the period gap are different if the VY Scl systems are classed with the nova-like variables, but the same when the VY Scl phenomenon is classed with the dwarf nova outbursts. For the remaining nova-like variables, the period gap is no longer significant. Classification of the VY Scl phenomenon with dwarf novae suggests that dwarf nova outbursts are caused by variation in mass transfer from the donor. Absence of the period gap obviates the need for models explaining it, and invalidates one piece of evidence for the importance of magnetic braking for the evolution of cataclysmic variables and of low-mass binaries in general.

The early ultraviolet, optical, and radio evolution of the soft X-ray transient GRO J0422+32

NASA Technical Reports Server (NTRS)

Shrader, C. R.; Wagner, R. Mark; Hjellming, R. M.; Han, X. H.; Starrfield, S. G.

1994-01-01

We have monitored the evolution of the transient X-ray source GRO J0422+32 from approximately 2 weeks postdiscovery into its early decline phase at ultraviolet, optical, and radio wavelengths. Optical and ultraviolet spectra exhibit numerous, but relatively weak, high-excitation emission lines such as those arising from He II, N III, N V, and C IV superposed on an intrinsically blue continuum. High-resolution optical spectroscopy reveals line profiles which are double peaked, and in the case of the higher order Balmer lines, superposed on a broad absorption profile. The early outburst optical-ultraviolet continuum energy distribution is well represented by a two power-law fit with a break at approximately equal 4000 A. Radio observations with the Very Large Array (VLA) reveal a flat-spectrum source, slowly increasing in intensity at the earliest epochs observed, followed by an approximate power-law decay light curve with an index of -1. Light curves for each wavelength domain are presented and discussed. Notable are the multiple secondary outbursts seen in the optical more than 1 year postdiscovery, and spectral changes associated with secondary rises seen in the radio and UV. We find that the ultraviolet and optical characteristics of GRO J0422+32 as well as its radio evolution, are similar to other recent well-observed soft X-ray transients (also called X-ray novae) such as Cen X-4, A0620-00 (V616 Mon), and Nova Muscae 1991 (GS 1124-683), suggesting that GRO J0422+32 is also a member of that subclass of low-mass X-ray binaries. We present definitive astrometric determination of the source position, and place an upper limit of R approximately equals 20 from our analysis of the Palomar Observatory Sky Survey (POSS). Additionally, we derive distinct values for color excess from analysis of the optical (E(B-V) = 0.23) and ultraviolet (E(B-V) = 0.4) data, suggesting an intrinsic magnitude of 19-19.5 for the progenitor if it is mid-K dwarf. This leads to a likely range of 2.4-3.0 kpc for the source distance, which is consistent with our separate estimate of 2.4 +/- 0.4 kpc based on measurement of the NaD interstellar line profile. Adopting 2.4 kpc and E(B-V) = 0.23, the outburst absolute magnitude was M approximately equals 0.0, which is a typical value for this class of objects.

The Photometric Evolution of the Classical Nova V723 Cassiopeia from 2006 through 2016

NASA Astrophysics Data System (ADS)

Hamilton-Drager, Catrina M.; Lane, Ryan I.; Recine, Kristen A.; Ljungquist, Lindsey S.; Grant, Jacob A.; Shrader, Katherine; Frymark, Derek G.; Dornbush, Eric M.; Richey-Yowell, Tyler; Boyle, Robert J.; Schwarz, Greg J.; Page, Kim L.

2018-02-01

We present photometric data of the classical nova, V723 Cas (Nova Cas 1995), over a span of 10 years (2006 through 2016) taken with the 0.9 m telescope at Lowell Observatory, operated as the National Undergraduate Research Observatory (NURO) on Anderson Mesa near Flagstaff, Arizona. A photometric analysis of the data produced light curves in the optical bands (Bessel B, V, and R filters). The data analyzed here reveal an asymmetric light curve (steep rise to maximum, followed by a slow decline to minimum), the overall structure of which exhibits pronounced evolution including a decrease in magnitude from year to year, at the rate of ∼0.15 mag yr‑1. We model these data with an irradiated secondary and an accretion disk with a hot spot using the eclipsing binary modeling program Nightfall. We find that we can model reasonably well each season of observation by changing very few parameters. The longitude of the hot spot on the disk and the brightness of the irradiated spot on the companion are largely responsible for the majority of the observed changes in the light curve shape and amplitude until 2009. After that, a decrease in the temperature of the white dwarf is required to model the observed light curves. This is supported by Swift/X-Ray Telescope observations, which indicate that nuclear fusion has ceased, and that V723 Cas is no longer detectable in the X-ray.

Quark-nova remnants. I. The leftover debris with applications to SGRs, AXPs, and XDINs

NASA Astrophysics Data System (ADS)

Ouyed, R.; Leahy, D.; Niebergal, B.

2007-10-01

We explore the formation and evolution of debris ejected around quark stars in the Quark Nova scenario, and the application to Soft Gamma-ray Repeaters (SGRs) and Anomolous X-ray Pulsars (AXPs). If an isolated neutron star explodes as a Quark Nova, an iron-rich shell of degenerate matter forms from its crust. This model can account for many of the observed features of SGRs and AXPs such as: (i) the two types of bursts (giant and regular); (ii) the spin-up and spin-down episodes during and following the bursts with associated increases in dot{P}; (iii) the energetics of the boxing day burst, SGR1806+20; (iv) the presence of an iron line as observed in SGR1900+14; (v) the correlation between the far-infrared and the X-ray fluxes during the bursting episode and the quiescent phase; (vi) the hard X-ray component observed in SGRs during the giant bursts, and (vii) the discrepancy between the ages of SGRs/AXPs and their supernova remnants. We also find a natural evolutionary relationship between SGRs and AXPs in our model which predicts that the youngest SGRs/AXPs are the most likely to exhibit strong bursting. Many features of X-ray Dim Isolated Neutron stars (XDINs) are also accounted for in our model such as, (i) the two-component blackbody spectra; (ii) the absorption lines around 300 eV; and (iii) the excess optical emission. Table 1 is only available in electronic form at http://www.aanda.org

Identification of high-mass X-ray binaries selected from XMM-Newton observations of the LMC★

NASA Astrophysics Data System (ADS)

van Jaarsveld, N.; Buckley, D. A. H.; McBride, V. A.; Haberl, F.; Vasilopoulos, G.; Maitra, C.; Udalski, A.; Miszalski, B.

2018-04-01

The Large Magellanic Cloud (LMC) currently hosts around 23 high-mass X-ray binaries (HMXBs) of which most are Be/X-ray binaries. The LMC XMM-Newton survey provided follow-up observations of previously known X-ray sources that were likely HMXBs, as well as identifying new HMXB candidates. In total, 19 candidate HMXBs were selected based on their X-ray hardness ratios. In this paper we present red and blue optical spectroscopy, obtained with Southern African Large Telescope and the South African Astronomical Observatory 1.9-m telescope, plus a timing analysis of the long-term optical light curves from OGLE to confirm the nature of these candidates. We find that nine of the candidates are new Be/X-ray binaries, substantially increasing the LMC Be/X-ray binary population. Furthermore, we present the optical properties of these new systems, both individually and as a group of all the BeXBs identified by the XMM-Newton survey of the LMC.

Novae in External Galaxies: M51, M87, and M101

NASA Astrophysics Data System (ADS)

Shafter, A. W.; Ciardullo, R.; Pritchet, C. J.

2000-02-01

As part of a program to determine the stellar population of novae, we have conducted a multiepoch Hα survey of the galaxies M51, M87, and M101. A total of nine and 12 novae were detected in the spiral galaxies M51 and M101, respectively, during four epochs of observation, and two epochs of observation yielded a total of nine novae in the giant elliptical galaxy M87. After correcting for the effective survey time and for the fraction of luminosity sampled, we find global nova rates of 18+/-7, 91+/-34, and 12+/-4 novae per year for M51, M87, and M101, respectively. After normalizing to the total K-band luminosity of each galaxy, we estimate luminosity-specific nova rates for M51, M87, and M101 of 1.09+/-0.47, 2.30+/-0.99, and 0.97+/-0.38 novae per year per 1010 solar luminosities in K. When we compare these data with measured values for the luminosity-specific nova rates of other galaxies, we find no compelling evidence for a significant variation with Hubble type. Possible ramifications of this result are discussed within the context of current theoretical models for nova production in galaxies.

The NOvA Technical Design Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ayres, D.S.; Drake, G.R.; Goodman, M.C.

Technical Design Report (TDR) describes the preliminary design of the NOvA accelerator upgrades, NOvA detectors, detector halls and detector sites. Compared to the March 2006 and November 2006 NOvA Conceptual Design Reports (CDR), critical value engineering studies have been completed and the alternatives still active in the CDR have been narrowed to achieve a preliminary technical design ready for a Critical Decision 2 review. Many aspects of NOvA described this TDR are complete to a level far beyond a preliminary design. In particular, the access road to the NOvA Far Detector site in Minnesota has an advanced technical design atmore » a level appropriate for a Critical Decision 3a review. Several components of the accelerator upgrade and new neutrino detectors also have advanced technical designs appropriate for a Critical Decision 3a review. Chapter 1 is an Executive Summary with a short description of the NOvA project. Chapter 2 describes how the Fermilab NuMI beam will provide a narrow band beam of neutrinos for NOvA. Chapter 3 gives an updated overview of the scientific basis for the NOvA experiment, focusing on the primary goal to extend the search for {nu}{sub {mu}} {yields} {nu}{sub e} oscillations and measure the sin{sup 2}(2{theta}{sub 13}) parameter. This parameter has not been measured in any previous experiment and NOvA would extend the search by about an order of magnitude beyond the current limit. A secondary goal is to measure the dominant mode oscillation parameters, sin{sup 2}(2{theta}{sub 23}) and {Delta}m{sub 32}{sup 2} to a more precise level than previous experiments. Additional physics goals for NOvA are also discussed. Chapter 4 describes the Scientific Design Criteria which the Fermilab accelerator complex, NOvA detectors and NOvA detector sites must satisfy to meet the physics goals discussed in Chapter 3. Chapter 5 is an overview of the NOvA project. The changes in the design relative to the NOvA CDR are discussed. Chapter 6 summarizes the NOvA design performance relative to the Design Criteria set out in Chapter 4. Chapter 7 presents the Work Breakdown Structure dictionary at Level 3 and the Milestone dictionary. Chapters 8 through 17 then take each Level 2 WBS element of the NOvA project and present each part of the design in more detail than the overview given in Chapter 5. Specific technical design criteria are delineated for each part of the project in addition to the scientific design criteria outlined in Chapter 4. Changes in the design since the NOvA CDR are discussed in detail. The work remaining to bring each part of this preliminary design to a final design is outlined. Appendix A is a guide to other NOvA Project documentation with links to those documents.« less

A Hubble Space Telescope survey for novae in M87 – III. Are novae good standard candles 15 d after maximum brightness?

DOE PAGES

Shara, Michael M.; Doyle, Trisha F.; Pagnotta, Ashley; ...

2017-11-16

Ten weeks of daily imaging of the giant elliptical galaxy M87 with the Hubble Space Telescope (HST) has yielded 41 nova light curves of unprecedented quality for extragalactic cataclysmic variables. We have recently used these light curves to demonstrate that the observational scatter in the so-called maximum-magnitude rate of decline (MMRD) relation for classical novae is so large as to render the nova-MMRD useless as a standard candle. Here in this paper, we demonstrate that a modified Buscombe–de Vaucouleurs hypothesis, namely that novae with decline times t2 > 10 d converge to nearly the same absolute magnitude about two weeksmore » after maximum light in a giant elliptical galaxy, is supported by our M87 nova data. For 13 novae with daily sampled light curves, well determined times of maximum light in both the F606W and F814W filters, and decline times t 2 > 10 d we find that M87 novae display M606W,15 = -6.37 ± 0.46 and M814W,15 = -6.11 ± 0.43. If very fast novae with decline times t 2 < 10 d are excluded, the distances to novae in elliptical galaxies with stellar binary populations similar to those of M87 should be determinable with 1σ accuracies of ± 20 percent with the above calibrations.« less

A Hubble Space Telescope survey for novae in M87 – III. Are novae good standard candles 15 d after maximum brightness?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shara, Michael M.; Doyle, Trisha F.; Pagnotta, Ashley

Ten weeks of daily imaging of the giant elliptical galaxy M87 with the Hubble Space Telescope (HST) has yielded 41 nova light curves of unprecedented quality for extragalactic cataclysmic variables. We have recently used these light curves to demonstrate that the observational scatter in the so-called maximum-magnitude rate of decline (MMRD) relation for classical novae is so large as to render the nova-MMRD useless as a standard candle. Here in this paper, we demonstrate that a modified Buscombe–de Vaucouleurs hypothesis, namely that novae with decline times t2 > 10 d converge to nearly the same absolute magnitude about two weeksmore » after maximum light in a giant elliptical galaxy, is supported by our M87 nova data. For 13 novae with daily sampled light curves, well determined times of maximum light in both the F606W and F814W filters, and decline times t 2 > 10 d we find that M87 novae display M606W,15 = -6.37 ± 0.46 and M814W,15 = -6.11 ± 0.43. If very fast novae with decline times t 2 < 10 d are excluded, the distances to novae in elliptical galaxies with stellar binary populations similar to those of M87 should be determinable with 1σ accuracies of ± 20 percent with the above calibrations.« less

Broad-band characteristics of seven new hard X-ray selected cataclysmic variables

NASA Astrophysics Data System (ADS)

Bernardini, F.; de Martino, D.; Mukai, K.; Russell, D. M.; Falanga, M.; Masetti, N.; Ferrigno, C.; Israel, G.

2017-10-01

We present timing and spectral analysis of a sample of seven hard X-ray selected cataclysmic variable candidates based on simultaneous X-ray and optical observations collected with XMM-Newton, complemented with Swift/BAT and INTEGRAL /IBIS hard X-ray data and ground-based optical photometry. For six sources, X-ray pulsations are detected for the first time in the range of ˜296-6098 s, identifying them as members of the magnetic class. Swift J0927.7-6945, Swift J0958.0-4208, Swift J1701.3-4304, Swift J2113.5+5422 and possibly PBC J0801.2-4625 are intermediate polars (IPs), while Swift J0706.8+0325 is a short (1.7 h) orbital period polar, the 11th hard X-ray-selected identified so far. X-ray orbital modulation is also observed in Swift J0927.7-6945 (5.2 h) and Swift J2113.5+5422 (4.1 h). Swift J1701.3-4304 is discovered as the longest orbital period (12.8 h) deep eclipsing IP. The spectra of the magnetic systems reveal optically thin multitemperature emission between 0.2 and 60 keV. Energy-dependent spin pulses and the orbital modulation in Swift J0927.7-6945 and Swift J2113.5+5422 are due to intervening local high-density absorbing material (NH ˜ 1022 - 23 cm-2). In Swift J0958.0-4208 and Swift J1701.3-4304, a soft X-ray blackbody (kT ˜ 50 and ˜80 eV) is detected, adding them to the growing group of `soft' IPs. White dwarf masses are determined in the range of ˜ 0.58-1.18 M⊙, indicating massive accreting primaries in five of them. Most sources accrete at rates lower than the expected secular value for their orbital period. Formerly proposed as a long-period (9.4 h) nova-like CV, Swift J0746.3-1608 shows peculiar spectrum and light curves suggesting either an atypical low-luminosity CV or a low-mass X-ray binary.

Organic Materials For Optical Switching

NASA Technical Reports Server (NTRS)

Cardelino, Beatriz H.

1993-01-01

Equations predict properties of candidate materials. Report presents results of theoretical study of nonlinear optical properties of organic materials. Such materials used in optical switching devices for computers and telecommunications, replacing electronic switches. Optical switching potentially offers extremely high information throughout in compact hardware.

Synoptic GNIRS XD Spectra ToO Novae

NASA Astrophysics Data System (ADS)

Woodward, Chick; Helton, Andrew; Spitzer/Chandra Team

2007-02-01

Novae are important contributors to galactic chemical enrichment on local scales. NIR spectroscopy of novae provides information about the elemental abundances of the gas and dust in the ejecta dispersing into the ISM as well as kinematic information related to the outburst. We propose to obtain synoptic GNIRS spectra of select Target of Opportunity (ToO) novae in the Magellanic Clouds (MC) and the galaxy to study the dynamics of the ejecta, to determine the temporal evolution of coronal lines and recombination lines (measuring their strength and velocity profiles), and to determine abundances. Being all equidistant, MC nova permit a more robust analysis of distant-dependent physical parameters of outburst than is generally possible for Galactic novae. The GNIRS data will provide critical spectral coverage and synoptic data to complement extant Spitzer and Chandra nova programs. Triggering of the GNIRS program will occur when a nova becomes brighter than V=12 mag, (assuming that adequate PWFS guide stars exist) as reported in the IAUC or CBET.

Nova Discovery Efficiency 1890-2014; Only 43%±6% of the Brightest Nova Are Discovered

NASA Astrophysics Data System (ADS)

Schaefer, Bradley E.

2014-06-01

Galactic nova discovery has always been the domain of the best amateur astronomers, with the only substantial exception being the use of the Harvard plates from 1890-1947. (Modern CCD surveys have not produced any significant nova discoveries.) From 1890-1946, novae were discovered by gentlemen who deeply knew the stars in the sky and who checked for new stars on every clear night. This all changed when war surplus binoculars became commonly available, so the various organizations (e.g., AAVSO, BAA) instructed their hunters to use binoculars to regularly search small areas of the Milky Way. In the 1970s the hunters largely switched to blinking photographs, while they switched to CCD images in the 1990s, all exclusively in Milky Way regions. Currently, most hunters use 'go-to' scopes to look deeply only in the Milky Way, use weekly or monthly cadences, never go outside to look up at the light-polluted skies, and do not have the stars memorized at all. This situation is good for catching many faint novae, but is inefficient for catching the more isotropic and systematically-fast bright novae.I have made an exhaustive analysis of all known novae to isolate the effects on the relative discovery efficiency as a function of decade, the elongation from the Sun, the Moon's phase, the declination, the peak magnitude, and the duration of the peak. For example, the relative efficiency for novae south of declination -33° is 0.5 before 1953, 0.2 from 1953-1990, and 0.8 after 1990. My analysis gives the overall discovery efficiency to be 43%±6%, 30%, 22%, 12%, and 6% for novae peaking brighter than 2, 4, 6, 8, and 10 mag. Thus, the majority of first magnitude novae are being missed. The bright novae are lost because they are too close to the Sun, in the far south, and/or very fast. This is illustrated by the discovery rate for Vpeak<2 novae being once every five years before 1946, yet only one such nova (V1500 Cyg) has been seen in the last 68 years. A critical consequence of this result is that the nova rate for our Milky Way has doubled.

A Twenty-Year Survey of Novae in M31

NASA Astrophysics Data System (ADS)

Crayton, Hannah; Rector, Travis A.; Walentosky, Matthew J.; Shafter, Allen W.; Lauber, Stephanie; Pilachowski, Catherine A.; RBSE Nova Search Team

2018-06-01

Numerous surveys of M31 in search of extragalactic novae have been completed over the last century, with a total of more than 1000 having been discovered during this time. From these surveys it has been estimated that the number of novae that occur in M31 is approximately 65 yr-1 (Darnley et al. 2006). A fraction of these are recurrent novae that recur on the timescales of years to decades (Shafter et al. 2015). From 1997 to 2017 we completed observations of M31 with the KPNO/WIYN 0.9-meter telescope, which offers a wide field of view suitable for surveying nearly all of the bulge and much of the disk of M31. Observations were completed in Hα so as to better detect novae in the bulge of the galaxy, where most novae reside. Our survey achieves a limiting absolute magnitude per epoch of MHα ∼ 7.5 mag, which prior M31 nova surveys in Hα (e.g., Ciardullo et al. 1987; Shafter & Irby 2001) have shown to be sufficiently deep to detect a typical nova several months after eruption. By completing nearly all of the observations with the same telescope, cameras, and filters we were able to obtain a remarkably consistent dataset.Our survey offers several benefits as compared to prior surveys. Nearly 200 epochs of observations were completed during the survey period. Observations were typically completed on a monthly basis; although on several occasions we completed weekly and nightly observations to search for novae with faster decay rates. Thus we were sensitive to most of the novae that erupted in M31 during the survey period.Over twenty years we detected 316 novae. Our survey found 85% of the novae in M31 that were reported by other surveys completed during the same time range and in the same survey area as ours (Pietsch et al. 2007). We also discovered 39 novae that were not found by other surveys. We present the complete catalog of novae from our survey, along with example light curves. Among other uses, our catalog will be useful for improving estimates of nova rate in M31. We also identify 72 standard stars within the survey area that will be useful for future surveys.

An archive study of 18 old novae. I. The UV spectra

NASA Astrophysics Data System (ADS)

Selvelli, P.; Gilmozzi, R.

2013-12-01

Aims: We present an overview of the UV spectral properties of old novae as a class. The data and results of this paper, together with data from the outburst phases, will be utilized in a follow-up study to determine statistical properties and to investigate correlations among the physical parameters of the quiescent and eruptive phases. Methods: All the available IUE, HST, and FUSE archive data for 18 old novae were used to derive accurate and homogeneous estimates of the reddening from the 2175 Å extinction bump and to determine the intrinsic spectral energy distribution corresponding to the utilization of both existing extinction curves. We also measured all the emission and absorption lines. Results: We have found good agreement between spectra taken at different epochs and by different instruments, a clear indication of the near constancy of the SED on timescales of several years. With the possible exception of GK Per, the dereddened UV continua are represented well by a single-curve power-law distribution Fλ ∝ λ- α, with α in the range 0.32-2.55 for one curve and 0.35-2.88 for the other one. The extrapolation of the various UV power laws to the optical range yields values that are in good agreement with the V magnitudes. We interpret this result as evidence that the SED is dominated by the accretion disk in the UV and optical spectral regions. A detailed study of the emission spectrum has led to measuring and identifying more than one hundred features and to detecting several lines that are rather uncommon in other CVs and whose identification is uncertain. Based on INES data from the IUE satellite. Some of the data presented in this paper were obtained from the Multimission Archive at the Space Telescope Science Institute (MAST). Tables 2-7 and 10-14 are available in electronic form at http://www.aanda.orgThe final reduced spectra (FITS files) and full Table 2 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/560/A49

BVRI Hα Photometric Evolution of Nova 2007 IN M 33

NASA Astrophysics Data System (ADS)

Munari, U.; Siviero, A.; Henden, A.; Dintinjana, B.; Mikuž, H.; Ochner, P.; Tomasoni, S.

The BVRCIC and Hα light curves of Nova 2007, located in the galaxy M 33, are presented. They display the fastest decline ever observed for a nova in this galaxy (Δ B = 0.40 ± 0.01 mag/day). Color indices of the nova match those of its counterparts in the Galaxy. The nova was discovered when it was already two magnitudes down from maximum (estimated to have occurred on September 13 at B = 15.5 mag).

No Expanding Fireball: Resolving the Recurrent Nova RS Ophiuchi with Infrared Interferometry

NASA Astrophysics Data System (ADS)

Monnier, J. D.; Barry, R. K.; Traub, W. A.; Lane, B. F.; Akeson, R. L.; Ragland, S.; Schuller, P. A.; Le Coroller, H.; Berger, J.-P.; Millan-Gabet, R.; Pedretti, E.; Schloerb, F. P.; Koresko, C.; Carleton, N. P.; Lacasse, M. G.; Kern, P.; Malbet, F.; Perraut, K.; Kuchner, M. J.; Muterspaugh, M. W.

2006-08-01

Following the recent outburst of the recurrent nova RS Oph on 2006 February 12, we measured its near-infrared size using the IOTA, Keck, and PTI Interferometers at multiple epochs. The characteristic size of ~3 mas hardly changed over the first 60 days of the outburst, ruling out currently popular models whereby the near-infrared emission arises from hot gas in the expanding shock. The emission was also found to be significantly asymmetric, evidenced by nonzero closure phases detected by IOTA. The physical interpretation of these data depends strongly on the adopted distance to RS Oph. Our data can be interpreted as the first direct detection of the underlying RS Oph binary, lending support to the recent ``reborn red giant'' models of Hachisu & Kato. However, this result hinges on an RS Oph distance of <~540 pc, in strong disagreement with the widely adopted distance of ~1.6 kpc. At the farther distance, our observations imply instead the existence of a nonexpanding, dense, and ionized circumbinary gaseous disk or reservoir responsible for the bulk of the near-infrared emission. Longer baseline infrared interferometry is uniquely suited to distinguish between these models and to ultimately determine the distance, binary orbit, and component masses for RS Oph, one of the closest known (candidate) Type 1a supernova progenitor systems.

New outburst of the symbiotic nova AG Pegasi after 165 yr

NASA Astrophysics Data System (ADS)

Skopal, A.; Shugarov, S. Yu.; Sekeráš, M.; Wolf, M.; Tarasova, T. N.; Teyssier, F.; Fujii, M.; Guarro, J.; Garde, O.; Graham, K.; Lester, T.; Bouttard, V.; Lemoult, T.; Sollecchia, U.; Montier, J.; Boyd, D.

2017-08-01

Context. AG Peg is known as the slowest symbiotic nova, which experienced its nova-like outburst around 1850. After 165 yr, during June of 2015, it erupted again showing characteristics of the Z And-type outburst. Aims: The primary objective is to determine basic characteristics, the nature and type of the 2015 outburst of AG Peg. Methods: We achieved this aim by modelling the spectral energy distribution using low-resolution spectroscopy (330-750 nm; R = 500-1000), medium-resolution spectroscopy (420-720 nm; R 11 000), and UBVRCIC photometry covering the 2015 outburst with a high cadence. Optical observations were complemented with the archival HST and FUSE spectra from the preceding quiescence. Results: During the outburst, the luminosity of the hot component was in the range of 2-11 × 1037 (d/ 0.8 kpc)2 erg s-1, being in correlation with the light curve (LC) profile. To generate the maximum luminosity by the hydrogen burning, the white dwarf (WD) had to accrete at 3 × 10-7 M⊙ yr-1, which exceeds the stable-burning limit and thus led to blowing optically thick wind from the WD. We determined its mass-loss rate to a few × 10-6 M⊙ yr-1. At the high temperature of the ionising source, 1.5-2.3 × 105 K, the wind converted a fraction of the WD's photospheric radiation into the nebular emission that dominated the optical. A one order of magnitude increase of the emission measure, from a few × 1059 (d/ 0.8 kpc)2 cm-3 during quiescence, to a few × 1060 (d/ 0.8 kpc)2 cm-3 during the outburst, caused a 2 mag brightening in the LC, which is classified as the Z And-type of the outburst. Conclusions: The very high nebular emission and the presence of a disk-like H I region encompassing the WD, as indicated by a significant broadening and high flux of the Raman-scattered O vi 6825 Å line during the outburst, is consistent with the ionisation structure of hot components in symbiotic stars during active phases. Full Table 1 and Table 6 are only available at the CDS are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/604/A48

Simultaneous IUE and Ground Based Observations of SS Cygni and HL Canis Majoris

NASA Astrophysics Data System (ADS)

Mansperger, C. S.; Kaitchuck, R. H.; Garnavich, P.; Dinshaw, N.

1993-05-01

SS Cyg and HL CMa were observed by IUE for three consecutive nights in November of 1992. During the first two nights, simultaneous photometric ground based observations of SS Cyg were made at the Ball State University Observatory. SS Cyg and HL CMa were observed simultaneously with the 90-inch telescope at the Steward Observatory on the last two nights of this run. These spectroscopic observations covered the wavelength range of 4100 Angstroms to 5000 Angstroms, while the spectra taken with the short wavelength camera on IUE resulted in wavelength coverage from 1150 Angstroms to 1980 Angstroms. SS Cyg is a U Gem type dwarf nova with an orbital period of 6.6 hours. Good simultaneous UV and optical orbital coverage was obtained for this system. HL CMa is a Z Cam type dwarf nova with an outburst period of 18 days. The AAVSO reports that this system was in outburst 4 days after the observing run. Therefore, HL CMa may have been in a preoutburst state during these observations. The C IV and H \\beta emission lines appeared to have weakened during this time.

VizieR Online Data Catalog: Optical to NIR spectra of nova V2676 Oph 2012 (Raj+, 2017)

NASA Astrophysics Data System (ADS)

Raj, A.; Das, R. K.; Walter, F. M.

2017-09-01

Near-infrared observations were obtained using the 1.2m telescope of Mt.Abu Infrared Observatory from 2012 March 29 to June 18 and the SMARTS/CTIO 1.3m telescope. The SMARTS photometry is available on the SMARTS atlas (Walter+, 2012PASP..124.1057W). Optical spectra were obtained with the Asiago 1.22m telescope + B&C spectrograph. Further low-dispersion spectra and photometry were obtained using the SMARTS 1.5m facilities. We obtained 19 spectra on an irregular cadence and with various sky conditions from 2012 April 5 through 2012 June 24. The target was observed using the COSMOS long slit spectrograph at CTIO on 2015 May 8, some three years after the outburst. (3 data files).

Olivier Chesneau's Work on Low Mass Stars

NASA Astrophysics Data System (ADS)

Lagadec, E.

2015-12-01

During his too short career, Olivier Chesneau pioneered the study of the circumstellar environments of low mass evolved stars using very high angular resolution techniques. He applied state of the art high angular resolution techniques, such as optical interferometry and adaptive optics imaging, to the the study of a variety of objects, from AGB stars to Planetary Nebulae, via e.g. Born Again stars, RCB stars and Novae. I present here an overview of this work and most important results by focusing on the paths he followed and key encounters he made to reach these results. Olivier liked to work in teams and was very strong at linking people with complementary expertises to whom he would communicate his enthusiasm and sharp ideas. His legacy will live on through the many people he inspired.

School Psychology in Nova Scotia

ERIC Educational Resources Information Center

King, Sara; McGonnell, Melissa; Noyes, Amira

2016-01-01

Registration as a psychologist in Nova Scotia can be at the master's or doctoral level; however, the Nova Scotia Board of Examiners in Psychology has announced a move to the doctoral degree as the entry-level to practice. Many school psychologists in Nova Scotia practice at the master's level; therefore, this change could affect school psychology…

When does an old nova become a dwarf nova? Kinematics and age of the nova shell of the dwarf nova AT Cancri

NASA Astrophysics Data System (ADS)

Shara, Michael M.; Drissen, Laurent; Martin, Thomas; Alarie, Alexandre; Stephenson, F. Richard

2017-02-01

The Z Cam-type dwarf nova AT Cancri (AT Cnc) displays a classical nova (CN) shell, demonstrating that mass transfer in cataclysmic binaries decreases substantially after a CN eruption. The hibernation scenario of cataclysmic binaries predicts such a decrease, on a time-scale of a few centuries. In order to measure the time since AT Cnc's last CN eruption, we have measured the radial velocities of a hundred clumps in its ejecta with SITELLE, Canada-France-Hawaii Telescope's recently commissioned imaging Fourier transform spectrometer. These range from -455 to +490 km s-1. Coupled with the known distance to AT Cnc of 460 pc, the size of AT Cnc's shell, and a simple model of nova ejecta deceleration, we determine that the last CN eruption of this system occurred 330_{-90}^{+135} yr ago. This is the most rapid transition from a high mass-transfer rate, nova-like variable to a low mass-transfer rate, dwarf nova yet measured, and in accord with the hibernation scenario of cataclysmic binaries. We conclude by noting the similarity in the deduced outburst date (within a century of 1686 CE) of AT Cnc to a `guest star' reported in the constellation Cancer by Korean observers in 1645 CE.

A Search for Ultrafast Novae in M31

NASA Astrophysics Data System (ADS)

Sola, Nicole; Rector, Travis A.; Shafter, Allen W.; Horst, Chuck; Igarashi, Amy; Henze, Martin; Pilachowski, Catherine A.

2018-06-01

Numerous surveys in search of extragalactic novae have been completed over the last century. From Local Group surveys it has been estimated that the number of novae that occur in M31 is approximately 65 yr-1 (Darnley et al. 2006), with a total of more than 1000 having been discovered over the past century. A fraction of these are recurrent novae that recur on the timescales of years to decades (Shafter et al. 2015).Novae typically fade from view on timescales of weeks to months. However, Shara et al. (2017) present models that predict the existence of "ultrafast" novae that have two-magnitude decay times (t2) of less than a day. The remarkable recurrent nova M31N 2008-12a has a t2 time of ~2 days (e.g., Darnley et al. 2016). None faster than this have been seen in M31; however, most surveys of extragalactic novae use cadences of a day or longer, meaning such novae could be missed.In October 2017 we completed a two-week search for ultrafast novae in M31 with the WIYN 0.9m telescope. The telescope's Half-Degree Imager provided a field of view of a quarter square degree, which covers most of M31's bulge and part of the disk. Weather hampered observations on some nights, but for most nights we were able to obtain multiple observations of M31 on a near hourly basis. We present the results of our search.

Naval Observatory Vector Astrometry Software (NOVAS) Version 3.1:Fortran, C, and Python Editions

NASA Astrophysics Data System (ADS)

Kaplan, G. H.; Bangert, J. A.; Barron, E. G.; Bartlett, J. L.; Puatua, W.; Harris, W.; Barrett, P.

2012-08-01

The Naval Observatory Vector Astrometry Software (NOVAS) is a source - code library that provides common astrometric quantities and transformations to high precision. The library can supply, in one or two subroutine or function calls, the instantaneous celestial position of any star or planet in a variety of coordinate systems. NOVAS also provides access to all of the building blocks that go into such computations. NOVAS is used for a wide variety of applications, including the U.S. portions of The Astronomical Almanac and a number of telescope control systems. NOVAS uses IAU recommended models for Earth orientation, including the IAU 2006 precession theory, the IAU 2000A and 2000B nutation series, and diurnal rotation based on the celestial and terrestrial intermediate origins. Equinox - based quantities, such as sidereal time, are also supported. NOVAS Earth orientation calculations match those from SOFA at the sub - microarcsecond level for comparable transformations. NOVAS algorithms for aberration an d gravitational light deflection are equivalent, at the microarcsecond level, to those inherent in the current consensus VLBI delay algorithm. NOVAS can be easily connected to the JPL planetary/lunar ephemerides (e.g., DE405), and connections to IMCCE and IAA planetary ephemerides are planned. NOVAS Version 3.1 introduces a Python edition alongside the Fortran and C editions. The Python edition uses the computational code from the C edition and currently mimics the function calls of the C edition. Future versions will expand the functionality of the Python edition to exploit the object - oriented features of Python. In the Version 3.1 C edition, the ephemeris - access functions have been revised for use on 64 - bit systems and for improved performance in general. NOVAS source code, auxiliary files, and documentation are available from the USNO website (http://aa.usno.navy.mil/software/novas/novas_info.php).

Discovery of Optical Transient in M82 : P60-M82-081119

NASA Astrophysics Data System (ADS)

Kasliwal, M. M.; Cenko, S. B.; Rau, A.; Ofek, E. O.; Quimby, R.; Kulkarni, S. R.

2008-11-01

On UT 2008 Nov 19.536, P60-FasTING (Palomar 60-inch Fast Transients In Nearby Galaxies) discovered a possible nova in M82 at RA(J2000) = 09:55:58.390 DEC(J2000) = +69:40:56.17, offset from the nucleus by 29.5"E, 10.4"N. P60-M82-081119 had a brightness of g = 20.0 +/- 0.1 at peak corresponding to Mg = -7.8 at the distance of M82 (uncorrected for extinction). There is no counterpart in SDSS or SIMBAD.

Transient astronomy with the Gaia satellite.

PubMed

Hodgkin, Simon T; Wyrzykowski, Łukasz; Blagorodnova, Nadejda; Koposov, Sergey

2013-06-13

Gaia is a cornerstone European Space Agency astrometry space mission and a successor to the Hipparcos mission. Gaia will observe the whole sky for 5 years, providing a serendipitous opportunity for the discovery of large numbers of transient and anomalous events, e.g. supernovae, novae and microlensing events, gamma-ray burst afterglows, fallback supernovae, as well as theoretical or unexpected phenomena. In this paper, we discuss our preparations to use Gaia to search for transients at optical wavelengths, and briefly describe the early detection, classification and prompt publication of anomalous sources.

Design, analysis and test verification of advanced encapsulation systems

NASA Technical Reports Server (NTRS)

Garcia, A., III; Kallis, J. M.; Trucker, D. C.

1983-01-01

Analytical models were developed to perform optical, thermal, electrical and structural analyses on candidate encapsulation systems. From these analyses several candidate encapsulation systems were selected for qualification testing.

Nova M33N 2012-10a

NASA Astrophysics Data System (ADS)

Alothman, Nourah

In this thesis I present a study and measurement of a Nova in M33 galaxy type N 2012-10a (which is type of binary star) using data that were collected by the ROTSE IIIb robotic telescope and another observatory. I study the fundamental properties of the light curve and determined the brightness and the velocity of this type of nova. I analyzed the spectra that were measured by the Hobby-Eberly Telescope (HET) at the McDonald Observatory. In addition, I compared this type of nova to other types of Novae.

Nova-driven winds in globular clusters

NASA Technical Reports Server (NTRS)

Scott, E. H.; Durisen, R. H.

1978-01-01

Recent sensitive searches for H-alpha emission from ionized intracluster gas in globular clusters have set upper limits that conflict with theoretical predictions. It is suggested that nova outbursts heat the gas, producing winds that resolve this discrepancy. The incidence of novae in globular clusters, the conversion of kinetic energy of the nova shell to thermal energy of the intracluster gas, and the characteristics of the resultant winds are discussed. Calculated emission from the nova-driven models does not conflict with any observations to date. Some suggestions are made concerning the most promising approaches for future detection of intracluster gas on the basis of these models. The possible relationship of nova-driven winds to globular cluster X-ray sources is also considered.

The Berkeley SuperNova Ia Program (BSNIP): Dataset and Initial Analysis

NASA Astrophysics Data System (ADS)

Silverman, Jeffrey; Ganeshalingam, M.; Kong, J.; Li, W.; Filippenko, A.

2012-01-01

I will present spectroscopic data from the Berkeley SuperNova Ia Program (BSNIP), their initial analysis, and the results of attempts to use spectral information to improve cosmological distance determinations to Type Ia supernova (SNe Ia). The dataset consists of 1298 low-redshift (z< 0.2) optical spectra of 582 SNe Ia observed from 1989 through the end of 2008. Many of the SNe have well-calibrated light curves with measured distance moduli as well as spectra that have been corrected for host-galaxy contamination. I will also describe the spectral classification scheme employed (using the SuperNova Identification code, SNID; Blondin & Tonry 2007) which utilizes a newly constructed set of SNID spectral templates. The sheer size of the BSNIP dataset and the consistency of the observation and reduction methods make this sample unique among all other published SN Ia datasets. I will also discuss measurements of the spectral features of about one-third of the spectra which were obtained within 20 days of maximum light. I will briefly describe the adopted method of automated, robust spectral-feature definition and measurement which expands upon similar previous studies. Comparisons of these measurements of SN Ia spectral features to photometric observables will be presented with an eye toward using spectral information to calculate more accurate cosmological distances. Finally, I will comment on related projects which also utilize the BSNIP dataset that are planned for the near future. This research was supported by NSF grant AST-0908886 and the TABASGO Foundation. I am grateful to Marc J. Staley for a Graduate Fellowship.

Optical+Near-IR Bayesian Classification of Quasars

NASA Astrophysics Data System (ADS)

Mehta, Sajjan S.; Richards, G. T.; Myers, A. D.

2011-05-01

We describe the details of an optimal Bayesian classification of quasars with combined optical+near-IR photometry from the SDSS and UKIDSS LAS surveys. Using only deep co-added SDSS photometry from the "Stripe 82" region and requiring full four-band UKIDSS detections, we reliably identify 2665 quasar candidates with a computed efficiency in excess of 99%. Relaxing the data constraints to combinations of two-band detections yields up to 6424 candidates with minimal trade-off in completeness and efficiency. The completeness and efficiency of the sample are investigated with existing spectra from the SDSS, 2SLAQ, and AUS surveys in addition to recent single-slit observations from Palomar Observatory, which revealed 22 quasars from a subsample of 29 high-z candidates. SDSS-III/BOSS observations will allow further exploration of the completeness/efficiency of the sample over 2.2

Nova-like variables

NASA Technical Reports Server (NTRS)

Ladous, Constanze

1993-01-01

On grounds of different observable characteristics five classes of nova-like objects are distinguished: the UX Ursae Majoris stars, the antidwarf novae, the DQ Herculis stars, the AM Herculis stars, and the AM Canum Venaticorum stars. Some objects have not been classified specifically. Nova-like stars share most observable features with dwarf novae, except for the outburst behavior. The understanding is that dwarf novae, UX Ursae Majoris stars, and anti-dwarf novae are basically the same sort of objects. The difference between them is that in UX Ursae Majoris stars the mass transfer through the accretion disc always is high so the disc is stationary all the time; in anti-dwarf novae for some reason the mass transfer occasionally drops considerably for some time, and in dwarf novae it is low enough for the disc to undergo semiperiodic changes between high and low accretion events. DQ Herculis stars are believed to possess weakly magnetic white dwarfs which disrupt the inner disc at some distance from the central star; the rotation of the white dwarf can be seen as an additional photometric period. In AM Herculis stars, a strongly magnetic white dwarf entirely prevents the formation of an accretion disk and at the same time locks the rotation of the white dwarf to the binary orbit. Finally, AM Canum Venaticorum stars are believed to be cataclysmic variables that consist of two white dwarf components.

Optical, IUE, and ROSAT observations of the eclipsing nova-like variable V347 Puppis (LB 1800)

NASA Technical Reports Server (NTRS)

Mauche, Christopher W.; Raymond, John C.; Buckley, David A. H.; Mouchet, Martine; Bonnell, Jerry; Sullivan, Denis J.; Bonnet-Bidaud, Jean-Marc; Bunk, Wolfram H.

1994-01-01

Using time-resolved optical spectroscopy and UBVRI and high-speed photometry obtained at Mount Stromlo Observatory, Mount John University Observatory, and the South African Astronomical Observatory; International Ultraviolet Explorer (IUE) ultraviolet spectroscopy; and Roentgen Satellite (ROSAT) survey X-ray fluxes, we present a study of the accretion disk, hot spot, and emission line regions in the bright eclipsing nova-like variable V347 Pup (LB 1800). In the optical and UV, V347 Pup is a strong emission line source with a continuum spectrum which is remarkably red for a high-M cataclysmic variable. Consistent with its high inclination, we interpret the continuum spectrum as the superposition of the spectrum of the cool (T(sub eff) approximately 7000 K) outer edge and the hot (T(sub eff) approximately 100,000 K) inner regions of a self-eclipsed accretion disk. For the assumed parameters, the model matches the level and shape of the observed spectrum for an inclination of approximately 88 and a distance of approximately 300 pc. The prominent hump in the optical and UV light curves just before eclipse manifests the presence of the hot spot where the accretion stream strikes the edge of the disk. The wavelength dependence of the amplitude of the hump is best modeled by a spot having an effective temperature of approximately 25,000 K and an area of approximately 3 x 10(exp 18) sq cm if the spot radiates like a blackbody, or an effective temperatue of approximately 14,000 K and an area of approximately 3 x 10(exp 19) sq cm if it radiates with a stellar spectrum. In either case, the hot spot produces only one-tenth of the predicted luminosity for the assumed mass-transfer rate of 10(exp -8) solar mass/yr. Either the hot spot is 'buried' in the edge of the accretion disk, or a significant fraction of its luminosity is radiated away in lines. The difference in azimuth between the peak of the hump and the dynamically expected location of the hot spot suggests that the spot's emitting surface is rotated forward by approximately 36 deg relative to the edge of the disk.

Optical, IUE, and ROSAT observations of the eclipsing nova-like variable V347 Puppis (LB 1800)

NASA Astrophysics Data System (ADS)

Mauche, Christopher W.; Raymond, John C.; Buckley, David A. H.; Mouchet, Martine; Bonnell, Jerry; Sullivan, Denis J.; Bonnet-Bidaud, Jean-Marc; Bunk, Wolfram H.

1994-03-01

Using time-resolved optical spectroscopy and UBVRI and high-speed photometry obtained at Mount Stromlo Observatory, Mount John University Observatory, and the South African Astronomical Observatory; International Ultraviolet Explorer (IUE) ultraviolet spectroscopy; and Roentgen Satellite (ROSAT) survey X-ray fluxes, we present a study of the accretion disk, hot spot, and emission line regions in the bright eclipsing nova-like variable V347 Pup (LB 1800). In the optical and UV, V347 Pup is a strong emission line source with a continuum spectrum which is remarkably red for a high-M cataclysmic variable. Consistent with its high inclination, we interpret the continuum spectrum as the superposition of the spectrum of the cool (Teff approximately 7000 K) outer edge and the hot (Teff approximately 100,000 K) inner regions of a self-eclipsed accretion disk. For the assumed parameters, the model matches the level and shape of the observed spectrum for an inclination of approximately 88 and a distance of approximately 300 pc. The prominent hump in the optical and UV light curves just before eclipse manifests the presence of the hot spot where the accretion stream strikes the edge of the disk. The wavelength dependence of the amplitude of the hump is best modeled by a spot having an effective temperature of approximately 25,000 K and an area of approximately 3 x 1018 sq cm if the spot radiates like a blackbody, or an effective temperatue of approximately 14,000 K and an area of approximately 3 x 1019 sq cm if it radiates with a stellar spectrum. In either case, the hot spot produces only one-tenth of the predicted luminosity for the assumed mass-transfer rate of 10-8 solar mass/yr. Either the hot spot is 'buried' in the edge of the accretion disk, or a significant fraction of its luminosity is radiated away in lines. The difference in azimuth between the peak of the hump and the dynamically expected location of the hot spot suggests that the spot's emitting surface is rotated forward by approximately 36 deg relative to the edge of the disk.

Explosive lithium production in the classical nova V339 Del (Nova Delphini 2013).

PubMed

Tajitsu, Akito; Sadakane, Kozo; Naito, Hiroyuki; Arai, Akira; Aoki, Wako

2015-02-19

The origin of lithium (Li) and its production process have long been uncertain. Li could be produced by Big Bang nucleosynthesis, interactions of energetic cosmic rays with interstellar matter, evolved low-mass stars, novae, and supernova explosions. Chemical evolution models and observed stellar Li abundances suggest that at least half the Li may have been produced in red giants, asymptotic giant branch (AGB) stars, and novae. No direct evidence, however, for the supply of Li from evolved stellar objects to the Galactic medium has hitherto been found. Here we report the detection of highly blue-shifted resonance lines of the singly ionized radioactive isotope of beryllium, (7)Be, in the near-ultraviolet spectra of the classical nova V339 Del (Nova Delphini 2013) 38 to 48 days after the explosion. (7)Be decays to form (7)Li within a short time (half-life of 53.22 days). The (7)Be was created during the nova explosion via the alpha-capture reaction (3)He(α,γ)(7)Be (ref. 5). This result supports the theoretical prediction that a significant amount of (7)Li is produced in classical nova explosions.

A hydrodynamic study of a slow nova outburst. [computerized simulation of thermonuclear runaway in white dwarf envelope

NASA Technical Reports Server (NTRS)

Sparks, W. M.; Starrfield, S.; Truran, J. W.

1978-01-01

The paper reports use of a Lagrangian implicit hydrodynamics computer code incorporating a full nuclear-reaction network to follow a thermonuclear runaway in the hydrogen-rich envelope of a 1.25 solar-mass white dwarf. In this evolutionary sequence the envelope was assumed to be of normal (solar) composition and the resulting outburst closely resembles that of the slow nova HR Del. In contrast, previous CNO-enhanced models resemble fast nova outbursts. The slow-nova model ejects material by radiation pressure when the high luminosity of the rekindled hydrogen shell source exceeds the local Eddington luminosity of the outer layers. This is in contrast to the fast nova outburst where ejection is caused by the decay of the beta(+)-unstable nuclei. Nevertheless, radiation pressure probably plays a major role in ejecting material from the fast nova remnants. Therefore, the sequence from slow to fast novae can be interpreted as a sequence of white dwarfs with increasing amounts of enhanced CNO nuclei in their hydrogen envelopes, although other parameters such as the white-dwarf mass and accretion rate probably contribute to the observed variation between novae.

Detecting Nova Shells around known Cataclysmic Variable systems

NASA Astrophysics Data System (ADS)

Xhakaj, Enia; Kupfer, Thomas; Prince, Thomas A.

2017-01-01

Nova shells are hydrogen-rich nebulae around Cataclysmic Variables that are created when a Nova outburst takes place. Learning more about Nova shells can help us get a better understanding of the long-term evolution of white dwarfs in active Cataclysmic Variables. In this project, we present the search for Nova shells around 1700 Cataclysmic Variables, using Hα images from the Palomar Transient Factory (PTF) survey. The PTF Hα survey started in 2009 using the 48’’ Oschin telescope at Palomar Observatory and is the first of its type covering the whole northern hemisphere while reaching 18 mags in 60 seconds of exposure. We concentrated our search on the IAU catalogue of Historical Novae, as well as on the SDSS and the Ritter-Kolb catalogue of Cataclysmic Variables. We numerically analyzed radial profiles centered on the target sources to search for excess emission potentially associated with the shells. Out of 1700 Cataclysmic Variables present in these catalogues, we detected 25 Nova shells, out of which 20 are not observed before.

OPTICAL SPECTROSCOPIC OBSERVATIONS OF GAMMA-RAY BLAZAR CANDIDATES. VI. FURTHER OBSERVATIONS FROM TNG, WHT, OAN, SOAR, AND MAGELLAN TELESCOPES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Álvarez Crespo, N.; Massaro, F.; Milisavljevic, D.

Blazars, one of the most extreme classes of active galaxies, constitute so far the largest known population of γ-ray sources, and their number is continuously growing in the Fermi catalogs. However, in the latest release of the Fermi catalog there is still a large fraction of sources that are classified as blazar candidates of uncertain type (BCUs) for which optical spectroscopic observations are necessary to confirm their nature and their associations. In addition, about one-third of the γ-ray point sources listed in the Third Fermi-LAT Source Catalog (3FGL) are still unassociated and lacking an assigned lower-energy counterpart. Since 2012 wemore » have been carrying out an optical spectroscopic campaign to observe blazar candidates to confirm their nature. In this paper, the sixth of the series, we present optical spectroscopic observations for 30 γ-ray blazar candidates from different observing programs we carried out with the Telescopio Nazionale Galileo, William Herschel Telescope, Observatorio Astronómico Nacional, Southern Astrophysical Research Telescope, and Magellan Telescopes. We found that 21 out of 30 sources investigated are BL Lac objects, while the remaining targets are classified as flat-spectrum radio quasars showing the typical broad emission lines of normal quasi-stellar objects. We conclude that our selection of γ-ray blazar candidates based on their multifrequency properties continues to be a successful way to discover potential low-energy counterparts of the Fermi unidentified gamma-ray sources and to confirm the nature of BCUs.« less

Fritz Zwicky: Novae Become Supernovae

NASA Astrophysics Data System (ADS)

Koenig, T.

2005-12-01

The Swiss physicist Fritz Zwicky (1898-1974) dabbled in a plethora of disciplines, including astronomy and astrophysics. His dabblings were with vested interest and he has left quite an impact. His first great success was his nova research. In the early 1930s, while supermarkets and Superman were flying, he labelled the distinctly brighter nova Supernova. It had been believed that novae were the collision of two stars, but Zwicky came to recognize supernovae as a phenomenon quite distinct from novae. He and Walter Baade explained supernova by melding astronomy and physics and in this aim they created neutron stars, explained the origin of cosmic rays, initiated the first sky survey, and confirmed that a number of historical novae were indeed supernovae. This was truly an important work in the history of astrophysics.

Discovery of an old nova shell surrounding the cataclysmic variable V1315 Aql

NASA Astrophysics Data System (ADS)

Sahman, D. I.; Dhillon, V. S.; Littlefair, S. P.; Hallinan, G.

2018-07-01

Following our tentative discovery of a faint shell around V1315 Aql reported in Sahman et al., we undertook deep Hα imaging and intermediate-resolution spectroscopy of the shell. We find that the shell has its geometric centre located on V1315 Aql. The mass, spectral features, and density of the shell are consistent with other nova shells, rather than planetary nebulae or supernova remnants. The radial velocity of the shell is consistent with the systemic velocity of V1315 Aql. We believe this evidence strongly suggests that the shell originates from an earlier nova event. This is the first nova shell discovered around a nova-like and supports the theory of nova-induced cycles in mass transfer rates (hibernation theory) first proposed by Shara et al.

Hubble Space Telescope observations of the dwarf Nova Z Chamaeleontis through two eruption cycles

NASA Technical Reports Server (NTRS)

Robinson, E. L.; Wood, Janet H.; Bless, R. C.; Clemens, J. C.; Dolan, J. F.; Elliot, J. L.; Nelson, M. J.; Percival, J. W.; Taylor, M. J.; Van Citters, G. W.

1995-01-01

We have obtained the first high-speed photometry of the eclipsing dwarf nova Z Cha at ultraviolet wavelengths with the Hubble Space Telescope (HST). We observed the eclipse roughly every 4 days over two cycles of the normal eruptions of Z Cha, giving a uniquely complete coverage of its outburst cycle. The accretion disk dominated the ultraviolet light curve of Z Cha at the peak of an eruption; the white dwarf, the bright spot on the edge of the disk, and the boundary layer were all invisible. We were able to obtain an axisymmetric map of the accretion disk at this time only by adopting a flared disk with an opening angle of approximately 8 deg. The run of brightness temperature with radius in the disk at the peak of the eruption was too flat to be consistent with a steady state, optically thick accretion disk. The local rate of mass flow through the disk was approximately 5 x 10(exp -10) solar masses/yr near the center of the disk and approximately 5 x 10(exp -9) solar masses/yr near the outer edge. The white dwarf, the accretion disk, and the boundary layer were all significant contributors to the ultraviolet flux on the descending branches of the eruptions. The temperature of the white dwarf during decline was 18,300 K less than T(sub wd) less than 21,800 K, which is significantly greater than at minimum light. Six days after the maximum of an eruption Z Cha has faded to near minimum light at ultraviolet wavelenghts, but was still approximately 70% brighter at minimum light in the B band. About one-quarter of the excess flux in the B band came from the accretion disk. Thus, the accretion disk faded and became invisible at ultraviolet wavelengths before it faded at optical wavelenghts. The disk did, however, remain optically thick and obscured the lower half of the white dwarf at ultraviolet and possibly at optical wavelenghts for 2 weeks after the eruption ended. By the third week after eruptiuons the eclipse looked like a simple occultation of an unobscured, spherical white dwarf by a dark secondary star. The center of the accretion disk was, therfore, optically thin at ultraviolet wavelenghts and the boundary layer was too faint to be visible.

DISCOVERING THE MISSING 2.2 < z < 3 QUASARS BY COMBINING OPTICAL VARIABILITY AND OPTICAL/NEAR-INFRARED COLORS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu Xuebing; Wang Ran; Bian Fuyan

2011-09-15

The identification of quasars in the redshift range 2.2 < z < 3 is known to be very inefficient because the optical colors of such quasars are indistinguishable from those of stars. Recent studies have proposed using optical variability or near-infrared (near-IR) colors to improve the identification of the missing quasars in this redshift range. Here we present a case study combining both methods. We select a sample of 70 quasar candidates from variables in Sloan Digital Sky Survey (SDSS) Stripe 82, which are non-ultraviolet excess sources and have UKIDSS near-IR public data. They are clearly separated into two partsmore » on the Y - K/g - z color-color diagram, and 59 of them meet or lie close to a newly proposed Y - K/g - z selection criterion for z < 4 quasars. Of these 59 sources, 44 were previously identified as quasars in SDSS DR7, and 35 of them are quasars at 2.2 < z < 3. We present spectroscopic observations of 14 of 15 remaining quasar candidates using the Bok 2.3 m telescope and the MMT 6.5 m telescope, and successfully identify all of them as new quasars at z = 2.36-2.88. We also apply this method to a sample of 643 variable quasar candidates with SDSS-UKIDSS nine-band photometric data selected from 1875 new quasar candidates in SDSS Stripe 82 given by Butler and Bloom based on the time-series selections, and find that 188 of them are probably new quasars with photometric redshifts at 2.2 < z < 3. Our results indicate that the combination of optical variability and optical/near-IR colors is probably the most efficient way to find 2.2 < z < 3 quasars and is very helpful for constructing a complete quasar sample. We discuss its implications for ongoing and upcoming large optical and near-IR sky surveys.« less

Synthesis of C-rich dust in CO nova outbursts

NASA Astrophysics Data System (ADS)

José, Jordi; Halabi, Ghina M.; El Eid, Mounib F.

2016-09-01

Context. Classical novae are thermonuclear explosions that take place in the envelopes of accreting white dwarfs in stellar binary systems. The material transferred onto the white dwarf piles up under degenerate conditions, driving a thermonuclear runaway. In these outbursts, about 10-7-10-3 M⊙, enriched in CNO and sometimes other intermediate-mass elements (e.g., Ne, Na, Mg, or Al for ONe novae) are ejected into the interstellar medium. The large concentrations of metals spectroscopically inferred in the nova ejecta reveal that the solar-like material transferred from the secondary mixes with the outermost layers of the underlying white dwarf. Aims: Most theoretical models of nova outbursts reported to date yield, on average, outflows characterized by O > C, from which, in principle, only oxidized condensates (e.g., O-rich grains) would be expected. Methods: To specifically address whether CO novae can actually produce C-rich dust, six different hydrodynamic nova models have been evolved, from accretion to the expansion and ejection stages, with different choices for the composition of the substrate with which the solar-like accreted material mixes. Updated chemical profiles inside the H-exhausted core have been used, based on stellar evolution calculations for a progenitor of 8 M⊙ through H- and He-burning phases. Results: We show that these profiles lead to C-rich ejecta after the nova outburst. This extends the possible contribution of novae to the inventory of presolar grains identified in meteorites, particularly in a number of carbonaceous phases (I.e., nanodiamonds, silicon carbides, and graphites).

Naval Observatory Vector Astrometry Software (NOVAS) Version 3.1, Introducing a Python Edition

NASA Astrophysics Data System (ADS)

Barron, Eric G.; Kaplan, G. H.; Bangert, J.; Bartlett, J. L.; Puatua, W.; Harris, W.; Barrett, P.

2011-01-01

The Naval Observatory Vector Astrometry Software (NOVAS) is a source-code library that provides common astrometric quantities and transformations. NOVAS calculations are accurate at the sub-milliarcsecond level. The library can supply, in one or two subroutine or function calls, the instantaneous celestial position of any star or planet in a variety of coordinate systems. NOVAS also provides access to all of the building blocks that go into such computations. NOVAS Version 3.1 introduces a Python edition alongside the Fortran and C editions. The Python edition uses the computational code from the C edition and, currently, mimics the function calls of the C edition. Future versions will expand the functionality of the Python edition to harness the object-oriented nature of the Python language, and will implement the ability to handle large quantities of objects or observers using the array functionality in NumPy (a third-party scientific package for Python). NOVAS 3.1 also adds a module to transform GCRS vectors to the ITRS; the ITRS to GCRS transformation was already provided in NOVAS 3.0. The module that corrects an ITRS vector for polar motion has been modified to undo that correction upon demand. In the C edition, the ephemeris-access functions have been revised for use on 64-bit systems and for improved performance in general. NOVAS, including documentation, is available from the USNO website (http://www.usno.navy.mil/USNO/astronomical-applications/software-products/novas).

Life after eruption VII: A search for stunted outbursts in thirteen post-novae

NASA Astrophysics Data System (ADS)

Vogt, N.; Tappert, C.; Puebla, E. C.; Fuentes-Morales, I.; Ederoclite, A.; Schmidtobreick, L.

2018-06-01

The results of a photometric campaign during three observing seasons 2013 - 2016 at the Cerro Tololo International Observatory (1.3-meter SMARTS telescope) are presented. The aim was to detect "stunted" outbursts in a total of 13 post novae more than 38 years after maximum brightness registered in their nova eruption light curve. In six of the targets (V728 Sco 1862, V1059 Sgr 1898, V849 Oph 1919, V363 Sgr 1927, HS Pup 1963 and V2572 Sgr 1969) we detected such dwarf nova-like mini-outbursts, with mean amplitudes between 0.2m and 2.2m and typical FWHM of 4-11 days, repeating every 9-32 days. The most regular outburst behavior is present in the eclipsing post-nova V728 Sco. In our sample there is no significant correlation between the occurrences of stunted outbursts and the time passed since the nova eruption maximum. However, considering all 15 post-novae that have been reported to show stunted outbursts we found a possible tendency for increasing outburst amplitudes at the rate 0.52 ± 0.23 mag/century during 30 - 250 years after nova eruption. This tendency is still doubtful due to the low number of cases available. If the stunted outburst activity is related to the mass transfer rate \\dot{M}, we conclude that the secular decrease of \\dot{M} predicted by the hibernation scenario must be at much longer time scales than ˜200 years actually covered with post-nova observations.

ASM observations of X-ray flares from 4U 0115+63 and ASM 1354-64.

NASA Astrophysics Data System (ADS)

Tsunemi, H.; Kitamoto, S.

The authors report two X-ray flares detected with the All Sky Monitor (ASM) on board the GINGA satellite. One is from the recurrent X-ray pulsar 4U 0115+63 and the other is from the probable recurrent X-ray nova named ASM 1354-64. The maximum intensity for 4U 0115+63 was 180 mCrab and its duration was at least 22 days. Its spectrum was hard and resembled those of X-ray pulsars. The maximum intensity of ASM 1354-64 was 300 mCrab. It faded down below the detection limit at the end of August 1987. Its spectrum was soft and was similar to those of black hole candidates.

Near-Infrared Emission Lines of Nova Cassiopeiae 1995

NASA Astrophysics Data System (ADS)

Rudy, R. J.; Lynch, D. K.; Mazuk, S. M.; Venturini, C. C.; Puetter, R. C.

2000-12-01

The slow nova V 723 Cas (Nova Cas 1995) exhibits comparatively narrow emission features (FWHM 500 km sec-1) that make it ideal for classifying weak lines and lines blended with stronger features. We present spectra from 0.8-2.5 microns that track the gradual incrase in excitation of Nova Cas and discuss the emission lines that were present. During the period encompassed by these observations Nova Cas reached only moderate excitation-the most energetic coronal lines were [S VIII] 9913 and [Al IX] 20444; lines such as [S IX] 12523 that are prominent in some novae were not detected. Additional coronal lines present include [Si VI] 19641, [Ca VIII] 23205, and [Si VII] 24807. New lines identified include features of [Fe V], [Fe VI]. These iron features are not coronal lines, arising from transitions among low-lying terms rather than within the ground term itself. Also detected was [Ti VI] 17151 that was first identified in V1974 Cygni (Nova Cyg 1992), and possibly [Ti VII] 22050. Accurate wavelengths for a number of unidentified lines are also presented. These unidentified features are discussed with regard to their likely level of excitation and their presence in other novae. This work was supported by the IR&D program of the Aerospace Corporation. RCP acknowledges support from NASA.

Laying the foundation for a digital Nova Scotia

NASA Astrophysics Data System (ADS)

Bond, J.

2016-04-01

In 2013, the Province of Nova Scotia began an effort to modernize its coordinate referencing infrastructure known as the Nova Scotia Coordinate Referencing System (NSCRS). At that time, 8, active GPS stations were installed in southwest Nova Scotia to evaluate the technology's ability to address the Province's coordinate referencing needs. The success of the test phase helped build a business case to implement the technology across the entire Province. It is anticipated that by the end of 2015, 40 active GPS stations will be in place across Nova Scotia. This infrastructure, known as the Nova Scotia Active Control Stations (NSACS) network, will allow for instantaneous, centimetre level positioning across the Province. Originally designed to address the needs of the surveying community, the technology has also proven to have applications in mapping, machine automation, agriculture, navigation, emergency response, earthquake detection and other areas. In the foreseeable future, all spatial data sets captured in Nova Scotia will be either directly or indirectly derived from the NSACS network. The technology will promote high accuracy and homogenous spatial data sets across the Province. The technology behind the NSACS and the development of the system are described. Examples of how the technology is contributing to a digital Nova Scotia are presented. Future applications of the technology are also considered.

A Detailed Observational Analysis of V1324 Sco, the Most Gamma-Ray-luminous Classical Nova to Date

NASA Astrophysics Data System (ADS)

Finzell, Thomas; Chomiuk, Laura; Metzger, Brian D.; Walter, Frederick M.; Linford, Justin D.; Mukai, Koji; Nelson, Thomas; Weston, Jennifer H. S.; Zheng, Yong; Sokoloski, Jennifer L.; Mioduszewski, Amy; Rupen, Michael P.; Dong, Subo; Starrfield, Sumner; Cheung, C. C.; Woodward, Charles E.; Taylor, Gregory B.; Bohlsen, Terry; Buil, Christian; Prieto, Jose; Wagner, R. Mark; Bensby, Thomas; Bond, I. A.; Sumi, T.; Bennett, D. P.; Abe, F.; Koshimoto, N.; Suzuki, D.; Tristram, P. J.; Christie, Grant W.; Natusch, Tim; McCormick, Jennie; Yee, Jennifer; Gould, Andy

2018-01-01

It has recently been discovered that some, if not all, classical novae emit GeV gamma-rays during outburst, but the mechanisms involved in the production ofgamma-rays are still not well understood. We present here a comprehensive multiwavelength data set—from radio to X-rays—for the most gamma-ray-luminous classical nova to date, V1324 Sco. Using this data set, we show that V1324 Sco is a canonical dusty Fe II-type nova, with a maximum ejecta velocity of 2600 km s‑1 and an ejecta mass of a few × {10}-5 {M}ȯ . There is also evidence for complex shock interactions, including a double-peaked radio light curve which shows high brightness temperatures at early times. To explore why V1324 Sco was so gamma-ray luminous, we present a model of the nova ejecta featuring strong internal shocks and find that higher gamma-ray luminosities result from higher ejecta velocities and/or mass-loss rates. Comparison of V1324 Sco with other gamma-ray-detected novae does not show clear signatures of either, and we conclude that a larger sample of similarly well-observed novae is needed to understand the origin and variation of gamma-rays in novae.

Chandra Discovers Eruption and Pulsation in Nova Outburst

NASA Astrophysics Data System (ADS)

2001-09-01

NASA's Chandra X-ray Observatory has discovered a giant outburst of X-rays and unusual cyclical pulsing from a white dwarf star that is closely orbiting another star -- the first time either of these phenomena has been seen in X-rays. The observations are helping scientists better understand the thermonuclear explosions that occur in certain binary star systems. The observations of Nova Aquilae were reported today at the "Two Years of Science with Chandra" symposium by an international team led by Sumner Starrfield of Arizona State University. "We found two important results in our Chandra observations. The first was an underlying pulsation every 40 minutes in the X-ray brightness, which we believe comes from the cyclical expansion and contraction of the outer layers of the white dwarf," said Starrfield. "The other result was an enormous flare of X-rays that lasted for 15 minutes. Nothing like this has been seen before from a nova, and we don't know how to explain it." Novas occur on a white dwarf (a star which used up all its nuclear fuel and shrank to roughly the size of the Earth) that is orbiting a normal size star. Strong gravity tides drag hydrogen gas off the normal star and onto the white dwarf, where it can take more than 100,000 years for enough hydrogen to accumulate to ignite nuclear fusion reactions. Gradually, these reactions intensify until a cosmic-sized hydrogen bomb blast results. The outer layers of the white dwarf are then blown away, producing a nova outburst that can be observed for a period of months to years as the material expands into space. "Chandra has allowed us to see deep into the gases ejected by this giant explosion and extract unparalleled information on the evolution of the white dwarf whose surface is exploding," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics. The brightening of Nova Aquilae was first detected by optical astronomers in December 1999. "Although this star is at a distance of more than 6,000 light years, it could be seen with the naked eye for about a month, during which it was about 100,000 times brighter than our own Sun," said R. Mark Wagner of the University of Arizona. Nova Aquilae Chandra observed the nova, so-called because early astronomers believed they heralded the appearance of a new star, four times from April 2000 through October 2000. "Our first Chandra observations showed that the expanding gas around Nova Aquilae was hot and nearly opaque," said Joachim Krautter of the State Observatory in Heidelberg, Germany. "When we looked months later with Chandra, the expanding gases cleared enough for us to see through them to the underlying star on which the explosion occurred." The latter Chandra X-ray data revealed the cyclical changes in brightness are due to the white dwarf expanding and shrinking over a 40-minute period. They also showed that the temperature on the surface of the white dwarf was 300,000 degrees Celsius, making Nova Aquilae one of the hottest stars ever observed to undergo such pulsations. "The observations told us that thermonuclear fusion reactions were still occurring on the surface layers of the white dwarf - more than eight months after the explosion first began!" said Robert Gehrz of the University of Minnesota. Other members of the team are Howard Bond (Space Telescope Science Institute), Yousaf Butt (Harvard-Smithsonian Center for Astrophysics), Koji Mukai (Goddard Space Flight Center), Peter Hauschildt (University of Georgia), Margarida Hernanz (Institute for Space Studies, Catalonia, Spain), Marina Orio (University of Wisconsin and the Torino Observatory in Italy), and Charles Woodward (University of Minnesota). Chandra observed Nova Aquilae for a total of 10 hours with the High Resolution Camera (HRC) and the Advanced CCD Imaging Spectrometer (ACIS). The HRC was built for NASA by the Smithsonian Astrophysical Observatory, Cambridge, MA. The ACIS instrument was built for NASA by the Massachusetts Institute of Technology, Cambridge, and Pennsylvania State University, University Park. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program. TRW, Inc., Redondo Beach, Calif., is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, Mass. Images associated with this release are available on the World Wide Web at: http://chandra.harvard.edu AND http://chandra.nasa.gov

High Resolution Optical Spectroscopy of the Classical Nova V5668 Sgr Showing the Presence of Lithium

NASA Astrophysics Data System (ADS)

Wagner, R. Mark; Woodward, Charles E.; Starrfield, Sumner; Ilyin, Ilya; Strassmeier, Klaus

2018-01-01

The classical nova (CN) V5668 Sgr was discovered on 2015 March 15.634 and initial optical spectra implied it was an Fe II-class CN. We obtained high resolution optical spectroscopy on 30 nights between 2015 April 3 and 2016 June 5 with the 2 x 8.4 m Large Binocular Telescope (LBT) and the 1.8 m Vatican Advanced Technology Telescope (VATT) using the Potsdam Echelle Polarimetric Spectroscopic Instrument (PEPSI). The spectra cover all or part of the 3830-9065 Å spectral region at a spectral resolution of up to 270,000 (1 km/s); the highest resolution currently available on any 8-10 m class telescope. The early spectra are dominated by emission lines of the Balmer and Paschen series of hydrogen, Fe II, Ca II, and Na I with P Cyg-type line profiles as well as emission lines of [O I]. Numerous interstellar lines and bands are readily apparent at high spectral resolution. The permitted line profiles show complex and dramatic variations in the multi-component P Cyg-type line profiles with time. We detect a weak blue-shifted absorption line at a velocity consistent with Li I 6708 Å when compared with the line profiles of Hβ, Fe II 5169 Å, and Na I D. This line is present in spectra obtained on 7 of 8 consecutive nights up to day 21 of the outburst; but absent on day 42 when it is evident that the ionization of the ejecta has significantly increased. The equivalent width of the line converted to a column density, and the resulting mass fraction, imply a significant enrichment of 7Li in the ejecta. 7Li is produced by the decay of unstable 7Be created during the thermonuclear runaway. The discovery of the resonance lines of 7Be II in the optical spectra of the recent CNe V339 Del, V2944 Oph, and V5668 Sgr by Tajitsu et al. (2016) and its subsequent decay to 7Li (half life of 53 days) suggests a significant enrichment of 7Li in the Galaxy from CNe is possible. Our observations of the Li I 6708 Å line in the early optical spectra of V5668 Sgr mark the second direct detection of Li in a CN following the detection of Li I in the early optical spectra of V1369 Cen by Izzo et al. (2015). SS acknowledges partial support from NSF and NASA grants to ASU. CEW acknowledges support from NASA.

Disc origin of broad optical emission lines of the TDE candidate PTF09djl

NASA Astrophysics Data System (ADS)

Liu, F. K.; Zhou, Z. Q.; Cao, R.; Ho, L. C.; Komossa, S.

2017-11-01

An otherwise dormant supermassive black hole (SMBH) in a galactic nucleus flares up when it tidally disrupts a star passing by. Most of the tidal disruption events (TDEs) and candidates discovered in the optical/UV have broad optical emission lines with complex and diverse profiles of puzzling origin. In this Letter, we show that the double-peaked broad H α line of the TDE candidate PTF09djl can be well modelled with a relativistic elliptical accretion disc and the peculiar substructures with one peak at the line rest wavelength and the other redshifted to about 3.5 × 104 km s-1 are mainly due to the orbital motion of the emitting matter within the disc plane of large inclination 88° and pericentre orientation nearly vertical to the observer. The accretion disc has an extreme eccentricity 0.966 and semimajor axis of 340 BH Schwarzschild radii. The viewing angle effects of large disc inclination lead to significant attenuation of He emission lines originally produced at large electron scattering optical depth and to the absence/weakness of He emission lines in the spectra of PTF09djl. Our results suggest that the diversities of line intensity ratios among the line species in optical TDEs are probably due to the differences of disc inclinations.

Evidence that the Planetary Candidate CVSO30c is a Background Star from Optical, Seeing-limited Data

NASA Astrophysics Data System (ADS)

Lee, Chien-Hsiu; Chiang, Po-Shih

2018-01-01

We report serendipitous optical imaging of CVSO30c, an exoplanet candidate associated with the pre-main-sequence T Tauri star CVSO30 that resides in the 25 Ori stellar cluster. We perform PSF modeling on our seeing-limited optical image to remove the lights from the host star (CVSO30), allowing us to extract photometry of CVSO30c to be g = 23.2 ± 0.2 (statistic) ± 0.1 (systematic) and r = 21.5 ± 0.1 (statistic) ± 0.1 (systematic) magnitudes, respectively. This is 170 and 80 times too bright in the g and r bands, respectively, if CVSO30c were an L0 substellar object as suggested by previous studies. The optical/infrared colors of CVSO30c are indicative of a stellar, not substellar object, while the object’s color–magnitude diagram position is strikingly inconsistent with expected values for a low-mass member of 25 Ori. Broadband photometry for CVSO30c is instead better fit by contaminants such as a background K3 giant or M subdwarf. Our study demonstrates that optical seeing-limited data can help clarify the nature of candidate wide separation planet-mass companions in young star-forming regions.

DAQ Software Contributions, Absolute Scale Energy Calibration and Background Evaluation for the NOvA Experiment at Fermilab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flumerfelt, Eric Lewis

2015-08-01

The NOvA (NuMI Off-axis v e [nu_e] Appearance) Experiment is a long-baseline accelerator neutrino experiment currently in its second year of operations. NOvA uses the Neutrinos from the Main Injector (NuMI) beam at Fermilab, and there are two main off-axis detectors: a Near Detector at Fermilab and a Far Detector 810 km away at Ash River, MN. The work reported herein is in support of the NOvA Experiment, through contributions to the development of data acquisition software, providing an accurate, absolute-scale energy calibration for electromagnetic showers in NOvA detector elements, crucial to the primary electron neutrino search, and through anmore » initial evaluation of the cosmic background rate in the NOvA Far Detector, which is situated on the surface without significant overburden. Additional support work for the NOvA Experiment is also detailed, including DAQ Server Administration duties and a study of NOvA’s sensitivity to neutrino oscillations into a “sterile” state.« less

On the interpretation and implications of nova abundances: An abundance of riches or an overabundance of enrichments

NASA Technical Reports Server (NTRS)

Livio, Mario; Truran, James W.

1994-01-01

We reexamine the question of the frequency of occurrence of oxygen-neon-magnesium (ONeMg) degenerate dwarfs in classical nova systems, in light of recent observations which have been interpreted as suggesting that 'neon novae' can be associated with relatively low mass white dwarfs. Determinations of heavy-element concentrations in nova ejecta are reviewed, and possible interpretations of their origin are examined. We conclude that, of the 18 classical novae for which detailed abundance analyses are availble, only two (or possibly three) seem unambiguously to demand the presence of an underlying ONeMg white dwarf: V693 CrA 1981, V1370 Aql 1982, and possibly QU Vul 1984. Three other novae which exhibit significant neon enrichments, relative to their total heavy-element concentrations, are RR Pic 1925, V977, Sco 1989, and LMC 1990 No. 1. This result is entirely consistent with present frequency estimates, and our interpretation of the lower levels of enrichment in other systems explains, in a natural way, the existence of relatively low mass white dwarfs in some of the 'neon' novae.

OGLE ATLAS OF CLASSICAL NOVAE. II. MAGELLANIC CLOUDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mróz, P.; Udalski, A.; Poleski, R.

2016-01-15

The population of classical novae in the Magellanic Clouds was poorly known because of a lack of systematic studies. There were some suggestions that nova rates per unit mass in the Magellanic Clouds were higher than in any other galaxy. Here, we present an analysis of data collected over 16 years by the OGLE survey with the aim of characterizing the nova population in the Clouds. We found 20 eruptions of novae, half of which are new discoveries. We robustly measure nova rates of 2.4 ± 0.8 yr{sup −1} (LMC) and 0.9 ± 0.4 yr{sup −1} (SMC) and confirm that the K-band luminosity-specific novamore » rates in both Clouds are 2–3 times higher than in other galaxies. This can be explained by the star formation history in the Magellanic Clouds, specifically the re-ignition of the star formation rate a few Gyr ago. We also present the discovery of the intriguing system OGLE-MBR133.25.1160, which mimics recurrent nova eruptions.« less

Early evolution of the extraordinary Nova Delphini 2013 (V339 Del)

NASA Astrophysics Data System (ADS)

Skopal, A.; Drechsel, H.; Tarasova, T.; Kato, T.; Fujii, M.; Teyssier, F.; Garde, O.; Guarro, J.; Edlin, J.; Buil, C.; Antao, D.; Terry, J.-N.; Lemoult, T.; Charbonnel, S.; Bohlsen, T.; Favaro, A.; Graham, K.

2014-09-01

Aims: We determine the temporal evolution of the luminosity (LWD), radius (RWD) and effective temperature (Teff) of the white dwarf (WD) pseudophotosphere of V339 Del from its discovery to around day 40. Another main objective was studying the ionization structure of the ejecta. Methods: These aims were achieved by modelling the optical/near-IR spectral energy distribution (SED) using low-resolution spectroscopy (3500-9200 Å), UBVRCIC and JHKLM photometry. Important insights in the physical conditions of the ejecta were gained from an analysis of the evolution of the Hα and Raman-scattered 6825 Å O vi line using medium-resolution spectroscopy (R ~ 10 000). Results: During the fireball stage (Aug. 14.8-19.9, 2013), Teff was in the range of 6000-12 000 K, RWD was expanding non-uniformly in time from ~66 to ~300 (d/ 3 kpc) R⊙, and LWD was super-Eddington, but not constant. Its maximum of ~9 × 1038 (d/ 3 kpc)2 erg s-1 occurred around Aug. 16.0, at the maximum of Teff, half a day before the visual maximum. After the fireball stage, a large emission measure of 1.0-2.0 × 1062 (d/ 3 kpc)2 cm-3 constrained the lower limit of LWD to be well above the super-Eddington value. The mass of the ionized region was a few × 10-4 M⊙, and the mass-loss rate was decreasing from ~5.7 (Aug. 22) to ~0.71 × 10-4 M⊙ yr-1 (Sept. 20). The evolution of the Hα line and mainly the transient emergence of the Raman-scattered O vi 1032 Å line suggested a biconical ionization structure of the ejecta with a disk-like H i region persisting around the WD until its total ionization, around day 40. On Sept. 20 (day 35), the model SED indicated a dust emission component in the spectrum. The dust was located beyond the H i zone, where it was shielded from the hard, ≳105 K, radiation of the burning WD at that time. Conclusions: Our extensive spectroscopic observations of the classical nova V339 Del allowed us to map its evolution from the very early phase after its explosion. It is evident that the nova was not evolving according to the current theoretical prediction. The unusual non-spherically symmetric ejecta of nova V339 Del and its extreme physical conditions and evolution during and after the fireball stage represent interesting new challenges for the theoretical modelling of the nova phenomenon. Based on data collected by amateur astronomers.

A DWARF NOVA IN THE GLOBULAR CLUSTER M13

DOE Office of Scientific and Technical Information (OSTI.GOV)

Servillat, M.; Van den Berg, M.; Grindlay, J.

Dwarf novae (DNe) in globular clusters (GCs) seem to be rare with only 13 detections in the 157 known Galactic GCs. We report the identification of a new DN in M13, the 14th DN identified in a GC to date. Using the 2 m Faulkes Telescope North, we conducted a search for stars in M13 that show variability over a year (2005-2006) on timescales of days and months. This led to the detection of one DN showing several outbursts. A Chandra X-ray source is coincident with this DN and shows both a spectrum and variability consistent with that expected frommore » a DN, thus supporting the identification. We searched for a counterpart in Hubble Space Telescope Advanced Camera for Surveys/Wide Field Camera archived images and found at least 11 candidates, of which we could characterize only the 7 brightest, including one with a 3{sigma} H{alpha} excess and a faint blue star. The detection of one DN when more could have been expected likely indicates that our knowledge of the global Galactic population of cataclysmic variables is too limited. The proportion of DNe may be lower than found in catalogs, or they may have a much smaller mean duty cycle ({approx}1%) as proposed by some population synthesis models and recent observations in the field.« less

Time-dependent disk accretion in X-ray Nova MUSCAE 1991

NASA Astrophysics Data System (ADS)

Mineshige, Shin; Hirano, Akira; Kitamoto, Shunji; Yamada, Tatsuya T.; Fukue, Jun

1994-05-01

We propose a new model for X-ray spectral fitting of binary black hole candidates. In this model, it is assumed that X-ray spectra are composed of a Comptonized blackbody (hard component) and a disk blackbody spectra (soft component), in which the temperature gradient of the disk, q identically equal to -d log T/d log r, is left as a fitting parameter. With this model, we have fitted X-ray spectra of X-ray Nova Muscae 1991 obtained by Ginga. The fitting shows that a hot cloud, which Compton up-scatters soft photons from the disk, gradually shrank and became transparent after the main peak. The temperature gradient turns out to be fairly constant and is q approximately 0.75, the value expected for a Newtonian disk model. To reproduce this value with a relativistic disk model, a small inclination angle, i approximately equal to 0 deg to 15 deg, is required. It seems, however, that the q-value temporarily decreased below 0.75 at the main flare, and q increased in a transient fashion at the second peak (or the reflare) occurring approximately 70 days after the main peak. Although statistics are poor, these results, if real, would indicate that the disk brightening responsible for the main and secondary peaks are initiated in the relatively inner portions of the disk.

HabEx Optical Telescope Assembly

NASA Technical Reports Server (NTRS)

Stahl, H. Philip

2017-01-01

Purpose: a) Introduce candidate optical telescope assembly (OTA) architectures. b) Illustrate design/analysis process. Agenda: a) Definitions, Specification & Assumptions. b.) 4-meter Monolithic Mirror Concept. c) 6.5-meter Segmented Mirror Concept.

Beryllium detection in the very fast nova ASASSN-16kt (V407 Lupi)

NASA Astrophysics Data System (ADS)

Izzo, L.; Molaro, P.; Bonifacio, P.; Della Valle, M.; Cano, Z.; de Ugarte Postigo, A.; Prieto, J. L.; Thöne, C.; Vanzi, L.; Zapata, A.; Fernandez, D.

2018-02-01

We present high-resolution spectroscopic observations of the fast nova ASASSN-16kt (V407 Lup). A close inspection of spectra obtained at early stages has revealed the presence of low-ionization lines, and among the others we have identified the presence of the ionised 7Be doublet in a region relatively free from possible contaminants. After studying their intensities, we have inferred that ASASSN-16kt has produced (5.9 - 7.7)× 10-9 M⊙ of 7Be. The identification of bright Ne lines may suggest that the nova progenitor is a massive (1.2 M⊙) oxygen-neon white dwarf. The high outburst frequency of oxygen-neon novae implies that they likely produce an amount of Be similar, if not larger, to that produced by carbon-oxygen novae, then confirming that classical novae are among the main factories of lithium in the Galaxy.

Nova Mus 2008 = QY Mus

NASA Astrophysics Data System (ADS)

Templeton, Matthew R.

2008-10-01

Nova Mus 2008 = QY Mus was discovered by William Liller, Vina del Mar, Chile, on 2008 September 28.998 UT at magnitude 8.6 (Tech Pan film + orange filter). The position is RA = 13h 16m 36.44s , Dec = -67d 36m 47.8s (from P. Nelson). This object was announced as a nova in IAU Circular 8990 (Daniel W.E. Green, editor). The nova classification was determined using low-resolution spectra by W. Liller indicating the presence of broad H-alpha lines at least 2300 angstroms wide. Several observers confirmed the nova and provided photometry. The position above was provided by Peter Nelson (Ellinbank, Vic., Aus.), and is averaged from four separate exposures (rms error approx. 0.4 arcseconds). The GCVS team have formally designated Nova Mus 2008 as QY MUS. Observations should be reported to the AAVSO International Database as QY MUS.

Swift J1822.3-1606: Optical spectroscopy of the counterpart candidates from the 10.4m GTC

NASA Astrophysics Data System (ADS)

de Ugarte Postigo, A.; Munoz-Darias, T.

2011-07-01

We have performed optical spectroscopy of the two objects (S1 and S2; ATEL #3496, #3502) present within the Swift/XRT error circle of the Soft Gamma-ray Repeater (SGR) candidate, Swift J1822.3-1606 (ATEL #3488, #3489, #3490, #3491, #3493, #3501, #3503). Observations were performed on July 20, 2011 using the OSIRIS spectrograph at the 10.4m Gran Telescopio de Canarias (GTC) telescope in La Palma, Spain.

Optical Radiation: Susceptibility and Countermeasures

DTIC Science & Technology

1998-12-01

1995). "Early Visual Acuity Side Effects After Laser Retinal Photocoagulation in Diabetic Retinopathy ," W.D. Kosnik, L. Marouf, and M. Myers...tests. The automatic positioner (AMPS) coupled with the automatic optical test system (PEATS) permits timely and consistent evaluation of candidate...Science and Engineering OR:S&C Optical Radiation: Susceptibility and Countermeasures OSADS Optical Signature, Acquisition, and Detection System

T Pyxidis: The First Cataclysmic Variable with a Collimated Jet

NASA Technical Reports Server (NTRS)

Shahbaz, T.; Livio, M.; Southwell, K. A.; Charles, P. A.

1997-01-01

We present the first observational evidence for a collimated jet in a cataclysmic variable system; the recurrent nova T Pyxidis. Optical spectra show bipolar components of H(alpha) with velocities approx. 1400 km/s, very similar to those observed in the supersoft X-ray sources and in SS 433. We argue that a key ingredient of the formation of jets in the supersoft X-ray sources and T Pyx (in addition to an accretion disk threaded by a vertical magnetic field), is the presence of nuclear burning on the surface of the white dwarf.

Selected highlights from the Extreme Ultraviolet Explorer

NASA Technical Reports Server (NTRS)

Bowyer, S.; Malina, R. F.

1995-01-01

We present a few scientific highlights from the Extreme Ultraviolet Explorer (EUVE) all-sky and deep surveys, from the EUVE Righ Angle Program, and from the EUVE Guest Observer Program. The First EUVE Source Catalog includes 410 extreme ultraviolet (EUV) sources detected in the initial processing of the EUVE all-sky data. A program of optical identification indicates that counterparts include cool star coronae, flare stars, hot white dwarfs, central stars of planetary nebulae, B star photospheres and winds, an X-ray binary, extragalactic objects (active galactic nuclei, BL Lacertae), solar system objects (Moon, Mars, Io,), supernova remnants, and two novae.

Spitzer Observations of the New Luminous Red Nova M85 OT2006-1

NASA Astrophysics Data System (ADS)

Rau, A.; Kulkarni, S. R.; Ofek, E. O.; Yan, L.

2007-04-01

M85 OT2006-1 is the latest and most brilliant addition to the small group of known luminous red novae (LRNe). An identifying characteristic of the previously detected events (M31 RV, V4332 Sgr, and V838 Mon) was a spectral redward evolution connected with an emerging infrared component following the optical decay. Here we report on the discovery of a similar feature in Keck NIRC and Spitzer photometry of M85 OT2006-1 6 months posteruption. We find that its 2.1-22 μm spectral energy distribution is best described by a blackbody with effective temperature Teff=950+/-150 K and bolometric luminosity L=2.9+0.4-0.5×105 Lsolar. Assuming spherical geometry, the blackbody effective radius, R=2.0+0.6-0.4×104 Rsolar, and corresponding expansion velocity, v=870+260-180 km s-1, are remarkably similar to the properties of M31 RV 70 days after its eruption. Furthermore, we propose a search strategy for LRNe in the local universe making use of the longevity of their infrared excess emission and discuss the expected number of events in the Spitzer Infrared Nearby Galaxies Survey.

MASTER OT J004207.99+405501.1/M31LRN 2015 luminous red nova in M31: discovery, light curve, hydrodynamics and evolution

NASA Astrophysics Data System (ADS)

Lipunov, V. M.; Blinnikov, S.; Gorbovskoy, E.; Tutukov, A.; Baklanov, P.; Krushinski, V.; Tiurina, N.; Balanutsa, P.; Kuznetsov, A.; Kornilov, V.; Gorbunov, I.; Shumkov, V.; Vladimirov, V.; Gress, O.; Budnev, N. M.; Ivanov, K.; Tlatov, A.; Gabovich, A.; Yurkov, V.; Sergienko, Yu.; Zalozhnykh, I.

2017-09-01

We report the discovery and multicolour (VRIW) photometry of the rare explosive star MASTER OT J004207.99+405501.1 - a luminous red nova - in the Andromeda galaxy M31N2015-01a. We use our original light curve acquired with identical MASTER Global Robotic Net telescopes in one photometric system: VRI during the first 30 d and W (unfiltered) during 70 d. Also, we added published multicolour photometry data to estimate the mass and energy of the ejected shell and we discuss the likely formation scenarios of outbursts of this type. We propose an interpretation of the explosion that is consistent with an evolutionary scenario where the merging of stellar components or the disruption of the common envelope of a close binary can explain some luminous red novae. Radiative hydrodynamic simulations of a luminous red nova were carried out in extended parameter space to fit its light curves. We find that the multicolour passband light curves of the luminous red nova are consistent with an initial common envelope radius of 10 R⊙, a merger mass of 3 M⊙ and an explosion energy of 3 × 1048 erg. As a result, the phenomenon of novae consists of two classes: classical nuclear novae and more rare events (red novae) connected with the loss of compact common envelopes.

Cecilia Payne-Gaposchkin, Henry Norris Russell Lecture: Fifty Years of Novae

NASA Astrophysics Data System (ADS)

Burbidge, E. M.

1999-05-01

It is easy to pick out my most memorable meeting of the AAS: the 149th meeting held in January, 1977, and hosted by the University of Hawaii, in Honolulu, HI. It was the meeting at which two traditions of the Society were broken, and we moved into the era of equal opportunity for women astronomers. Cecilia Payne-Gaposchkin received the highest award of the AAS: the Henry Norris Russell Lectureship. This award had never before been available to women, otherwise Cecilia would, years earlier, have been honored for the many achievements in her lifetime of renowned astronomical research. And I, the first woman to be elected President of the AAS, had the honor of presenting the illuminated scroll to Cecilia, and of introducing her on the platform where she delivered the Henry Norris Russell Prize Lecture, entitled ``Fifty Years of Novae"(1) . Cecilia opened by comparing the experience of young and old scientists in achieving exciting results from their research, and then led us through the history of the discoveries of and about some famous novae. She described the physical picture that emerged from studies of their light curves, their spectra, and the discovery of their binary nature. Three important tables were included, listing data on cataclysmic binaries (dwarf novae) and their link to the nova phenomenon in general. She recalled that she and Sergei Gaposchkin had hesitated between the names catastrophic and cataclysmic for the dwarf novae, and decided on the latter, from the dictionary definitions of those two terms: ``a cataclysm is a great and general flood" while a catastrophe ``is a final event". The nova phenomenon is recurrent, as are the dwarf novae, and both involve an outpouring of a flood of energy. She concluded by describing her 50 years' experience with novae as presenting ``the contemporary portrait of a nova", rather than a final picture, and by forecasting that the next 50 years of discovering and studying novae will be as full of surprises as the last. (1) Cecilia H. Payne-Gaposchkin, 1977, AJ, 82, 665.

Research activities in nuclear astrophysics and related areas

NASA Technical Reports Server (NTRS)

1996-01-01

NASA/GRO grant NAG 5-2081, at the University of Chicago, has provided support for a broad program of theoretical research in nuclear astrophysics and related areas, with regard to gamma-ray and hard X-ray emission from classical nova explosions. This research emphasized the possible detection of 22Na gamma-ray line emission from nearby novae involving ONeMg white dwarfs, the detailed examination of 26Al production in novae, and the possible detection of the predicted early gamma ray emission from novae that arises from the decay of the short lived, positron emitting isotopes of CNO elements. Studies of nova related problems have consumed an increasing fraction of the Principal Investigator's research efforts over the past decade. Current research addresses problems associated with the standard model for the outbursts of the classical novae: the occurrence of thermonuclear runaways (TNR) in the accreted hydrogen rich envelopes on white dwarfs in close binary systems (see, e.g., the reviews by Truran 1982; and Shara 1989). Research in progress and planned for the next three years has three main objectives: (1) to gain an improved understanding of the early evolution of the light curves of, particularly, the fastest novae; (2) to gain an improved understanding of the relative importance of the various possible mechanisms of envelope hydrogen depletion (e.g. winds, common envelope driven mass loss, and nuclear burning) to the long term evolution of novae in outburst; and (3) to seek to provide a somewhat more definitive statement of the role of classical novae in nucleosynthesis. Our proposed 2-D studies of convection during the early phases of the TNR and our systematic attempt to incorporate an improved treatment of radiation hydrodynamics into the hydrodynamic code utilized in our calculations, are particularly relevant to the first of these objectives. Further 2-D studies of the effects of common envelope evolution are intended to provide more realistic constraints on the mass depletion mechanisms. Finally, detailed calculations of the thermonuclear history of the matter ejected in novae will be carried out for representative nova configurations involving both carbon-oxygen (CO) and oxygen-neon-magnesium (ONeMg) white dwarfs.

A highly efficient silole-containing dithienylethene with excellent thermal stability and fatigue resistance: a promising candidate for optical memory storage materials.

PubMed

Chan, Jacky Chi-Hung; Lam, Wai Han; Yam, Vivian Wing-Wah

2014-12-10

Diarylethene compounds are potential candidates for applications in optical memory storage systems and photoswitchable molecular devices; however, they usually show low photocycloreversion quantum yields, which result in ineffective erasure processes. Here, we present the first highly efficient photochromic silole-containing dithienylethene with excellent thermal stability and fatigue resistance. The photochemical quantum yields for photocyclization and photocycloreversion of the compound are found to be high and comparable to each other; the latter of which is rarely found in diarylethene compounds. These would give rise to highly efficient photoswitchable material with effective writing and erasure processes. Incorporation of the silole moiety as a photochromic dithienylethene backbone also was demonstrated to enhance the thermal stability of the closed form, in which the thermal backward reaction to the open form was found to be negligible even at 100 °C, which leads to a promising candidate for use as photoswitchable materials and optical memory storage.

Discovery of an Apparent Nova in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Figueira, J.; Sin, P.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2017-12-01

The M81 nova monitoring collaboration reports the discovery of an apparent nova in M81 on a co-added 3150-s unfiltered CCD frame taken on 2017 Dec. 2.127 UT with the 0.65-m telescope at Ondrejov (OND).

Discovery of a Probable Nova in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2018-01-01

The M81 nova monitoring collaboration reports the discovery of a probable nova in M81 on a co-added 3150-s unfiltered CCD frame taken on 2018 Jan. 30.776 UT with the 0.65-m telescope at Ondrejov (OND).

Discovery of two Probable Novae in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Henze, M.; Sala, G.; Jose, J.; Figueira, J.; Sin, P.; Hernanz, M.; Williams, S. C.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2017-09-01

The M81 nova monitoring collaboration reports the discovery of two probable novae in M81 on a co-added 2700-s unfiltered CCD frame taken on 2017 Sep. 18.129 UT with the 0.65-m telescope at Ondrejov (OND).

Discovery of a Probable Nova in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Figueira, J.; Sin, P.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2017-12-01

The M81 nova monitoring collaboration reports the discovery of a probable nova in M81 on a co-added 2610-s unfiltered CCD frame taken on 2017 Dec. 26.016 UT with the 0.65-m telescope at Ondrejov (OND).

The disappearance and reformation of the accretion disc during a low state of FO Aquarii

NASA Astrophysics Data System (ADS)

Hameury, J.-M.; Lasota, J.-P.

2017-09-01

Context. FO Aquarii, an asynchronous magnetic cataclysmic variable (intermediate polar) went into a low state in 2016, from which it slowly and steadily recovered without showing dwarf nova outbursts. This requires explanation since in a low state, the mass-transfer rate is in principle too low for the disc to be fully ionised and the disc should be subject to the standard thermal and viscous instability observed in dwarf novae. Aims: We investigate the conditions under which an accretion disc in an intermediate polar could exhibit a luminosity drop of two magnitudes in the optical band without showing outbursts. Methods: We use our numerical code for the time evolution of accretion discs, including other light sources from the system (primary, secondary, hot spot). Results: We show that although it is marginally possible for the accretion disc in the low state to stay on the hot stable branch, the required mass-transfer rate in the normal state would then have to be extremely high, of the order of 1019 g s-1 or even larger. This would make the system so intrinsically bright that its distance should be much larger than allowed by all estimates. We show that observations of FO Aqr are well accounted for by the same mechanism that we have suggested as explaining the absence of outbursts during low states of VY Scl stars: during the decay, the magnetospheric radius exceeds the circularisation radius, so that the disc disappears before it enters the instability strip for dwarf nova outbursts. Conclusions: Our results are unaffected, and even reinforced, if accretion proceeds both via the accretion disc and directly via the stream during some intermediate stages; the detailed process through which the disc disappears still requires investigation.

Asynchronous polar V1500 Cyg: orbital, spin and beat periods

NASA Astrophysics Data System (ADS)

Pavlenko, E. P.; Mason, P. A.; Sosnovskij, A. A.; Shugarov, S. Yu; Babina, Ju V.; Antonyuk, K. A.; Andreev, M. V.; Pit, N. V.; Antonyuk, O. I.; Baklanov, A. V.

2018-06-01

The bright Nova Cygni 1975 is a rare nova on a magnetic white dwarf (WD). Later it was found to be an asynchronous polar, now called V1500 Cyg. Our multisite photometric campaign occurring 40 years post eruption covered 26-nights (2015-2017). The reflection effect from the heated donor has decreased, but still dominates the optical radiation with an amplitude ˜1m.5. The 0m.3 residual reveals cyclotron emission and ellipsoidal variations. Mean brightness modulation from night-to-night is used to measure the 9.6-d spin-orbit beat period that is due to changing accretion geometry including magnetic pole-switching of the flow. By subtracting the orbital and beat frequencies, spin-phase dependent light curves are obtained. The amplitude and profile of the WD spin light curves track the cyclotron emitting accretion regions on the WD and they vary systematically with beat phase. A weak intermittent signal at 0.137613-d is likely the spin period, which is 1.73(1) min shorter than the orbital period. The O-C diagram of light curve maxima displays phase jumps every one-half beat period, a characteristic of asynchronous polars. The first jump we interpret as pole switching between regions separated by 180°. Then the spot drifts during ˜ 0.1 beat phase before undergoing a second phase jump between spots separated by less than 180°. We trace the cooling of the still hot WD as revealed by the irradiated companion. The post nova evolution and spin-orbit asynchronism of V1500 Cyg continues to be a powerful laboratory for accretion flows onto magnetic white dwarfs.

The evolution of CNO isotopes: a new window on cosmic star formation history and the stellar IMF in the age of ALMA

NASA Astrophysics Data System (ADS)

Romano, D.; Matteucci, F.; Zhang, Z.-Y.; Papadopoulos, P. P.; Ivison, R. J.

2017-09-01

We use state-of-the-art chemical models to track the cosmic evolution of the CNO isotopes in the interstellar medium of galaxies, yielding powerful constraints on their stellar initial mass function (IMF). We re-assess the relative roles of massive stars, asymptotic giant branch (AGB) stars and novae in the production of rare isotopes such as 13C, 15N, 17O and 18O, along with 12C, 14N and 16O. The CNO isotope yields of super-AGB stars, novae and fast-rotating massive stars are included. Having reproduced the available isotope enrichment data in the solar neighbourhood, and across the Galaxy, and having assessed the sensitivity of our models to the remaining uncertainties, e.g. nova yields and star formation history, we show that we can meaningfully constrain the stellar IMF in galaxies using C, O and N isotope abundance ratios. In starburst galaxies, where data for multiple isotopologue lines are available, we find compelling new evidence for a top-heavy stellar IMF, with profound implications for their star formation rates and efficiencies, perhaps also their stellar masses. Neither chemical fractionation nor selective photodissociation can significantly perturb globally averaged isotopologue abundance ratios away from the corresponding isotope ones, as both these processes will typically affect only small mass fractions of molecular clouds in galaxies. Thus, the Atacama Large Millimeter Array now stands ready to probe the stellar IMF, and even the ages of specific starburst events in star-forming galaxies across cosmic time unaffected by the dust obscuration effects that plague optical/near-infrared studies.

Robo-AO Kepler Planetary Candidate Survey. III. Adaptive Optics Imaging of 1629 Kepler Exoplanet Candidate Host Stars

NASA Astrophysics Data System (ADS)

Ziegler, Carl; Law, Nicholas M.; Morton, Tim; Baranec, Christoph; Riddle, Reed; Atkinson, Dani; Baker, Anna; Roberts, Sarah; Ciardi, David R.

2017-02-01

The Robo-AO Kepler Planetary Candidate Survey is observing every Kepler planet candidate host star with laser adaptive optics imaging to search for blended nearby stars, which may be physically associated companions and/or responsible for transit false positives. In this paper, we present the results of our search for stars nearby 1629 Kepler planet candidate hosts. With survey sensitivity to objects as close as ˜0.″15, and magnitude differences Δm ≤slant 6, we find 223 stars in the vicinity of 206 target KOIs; 209 of these nearby stars have not been previously imaged in high resolution. We measure an overall nearby-star probability for Kepler planet candidates of 12.6 % +/- 0.9 % at separations between 0.″15 and 4.″0. Particularly interesting KOI systems are discussed, including 26 stars with detected companions that host rocky, habitable zone candidates and five new candidate planet-hosting quadruple star systems. We explore the broad correlations between planetary systems and stellar binarity, using the combined data set of Baranec et al. and this paper. Our previous 2σ result of a low detected nearby star fraction of KOIs hosting close-in giant planets is less apparent in this larger data set. We also find a significant correlation between detected nearby star fraction and KOI number, suggesting possible variation between early and late Kepler data releases.

Independent Discovery of a Probable Nova in M81

NASA Astrophysics Data System (ADS)

Kucakova, H.; Hornoch, K.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2018-03-01

The M81 nova monitoring collaboration reports the independent discovery of a probable nova in M81 on a co-added 1350-s unfiltered CCD frame taken on 2018 Mar. 21.952 UT with the 0.65-m telescope at Ondrejov.

Independent Discovery of a Probable Nova in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2018-04-01

The M81 nova monitoring collaboration reports the independent discovery of a probable nova in M81 on a co-added 2700-s unfiltered CCD frame taken on 2018 Apr. 2.815 UT with the 0.65-m telescope at Ondrejov.

Independent Discovery of an Apparent Nova in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2018-02-01

The M81 nova monitoring collaboration reports the independent discovery of an apparent nova in M81 on a co-added 2700-s unfiltered CCD frame taken on 2018 Feb. 19.039 UT with the 0.65-m telescope at Ondrejov (OND).

NOVA Fall 2002 Teacher's Guide.

ERIC Educational Resources Information Center

Ransick, Kristina; Rosene, Dale; Sammons, James; Turck, Mary

This NOVA teacher's guide presents activities, information, and teaching ideas from the Public Broadcasting System's (PBS) NOVA television program series. Episodes include: (1) "Mysterious Life of Caves" which investigates the role microbes play in the creation of some limestone caves; (2) "Lost Roman Treasure" which follows…

Comparison of nonsteroidal anti-inflammatory drugs and cyclooxygenase-2 (COX-2) inhibitors use in Australia and Nova Scotia (Canada)

PubMed Central

Barozzi, Nadia; Sketris, Ingrid; Cooke, Charmaine; Tett, Susan

2009-01-01

AIMS Cyclooxygenase-2 (COX-2) inhibitors were marketed aggressively and their rapid uptake caused safety concerns and budgetary challenges in Canada and Australia. The objectives of this study were to compare and contrast COX-2 inhibitors and nonselective nonsteroidal anti-inflammatory drug (ns-NSAID) use in Nova Scotia (Canada) and Australia and to identify lessons learned from the two jurisdictions. METHODS Ns-NSAID and COX-2 inhibitor Australian prescription data (concession beneficiaries) were downloaded from the Medicare Australia website (2001–2006). Similar Pharmacare data were obtained for Nova Scotia (seniors and those receiving Community services). Defined daily doses per 1000 beneficiaries day−1 were calculated. COX-2 inhibitors/all NSAIDs ratios were calculated for Australia and Nova Scotia. Ns-NSAIDs were divided into low, moderate and high risk for gastrointestinal side-effects and the proportions of use in each group were determined. Which drugs accounted for 90% of use was also calculated. RESULTS Overall NSAID use was different in Australia and Nova Scotia. However, ns-NSAID use was similar. COX-2 inhibitor dispensing was higher in Australia. The percentage of COX-2 inhibitor prescriptions over the total NSAID use was different in the two countries. High-risk NSAID use was much higher in Australia. Low-risk NSAID prescribing increased in Nova Scotia over time. The low-risk/high-risk ratio was constant throughout over the period in Australia and increased in Nova Scotia. CONCLUSIONS There are significant differences in Australia and Nova Scotia in use of NSAIDs, mainly due to COX-2 prescribing. Nova Scotia has a higher proportion of low-risk NSAID use. Interventions to provide physicians with information on relative benefits and risks of prescribing specific NSAIDs are needed, including determining their impact. PMID:19660008

On Presolar Stardust Grains from CO Classical Novae

NASA Astrophysics Data System (ADS)

Iliadis, Christian; Downen, Lori N.; José, Jordi; Nittler, Larry R.; Starrfield, Sumner

2018-03-01

About 30%–40% of classical novae produce dust 20–100 days after the outburst, but no presolar stardust grains from classical novae have been unambiguously identified yet. Although several studies claimed a nova paternity for certain grains, the measured and simulated isotopic ratios could only be reconciled, assuming that the grains condensed after the nova ejecta mixed with a much larger amount of close-to-solar matter. However, the source and mechanism of this potential post-explosion dilution of the ejecta remains a mystery. A major problem with previous studies is the small number of simulations performed and the implied poor exploration of the large nova parameter space. We report the results of a different strategy, based on a Monte Carlo technique, that involves the random sampling over the most important nova model parameters: the white dwarf composition; the mixing of the outer white dwarf layers with the accreted material before the explosion; the peak temperature and density; the explosion timescales; and the possible dilution of the ejecta after the outburst. We discuss and take into account the systematic uncertainties for both the presolar grain measurements and the simulation results. Only those simulations that are consistent with all measured isotopic ratios of a given grain are accepted for further analysis. We also present the numerical results of the model parameters. We identify 18 presolar grains with measured isotopic signatures consistent with a CO nova origin, without assuming any dilution of the ejecta. Among these, the grains G270_2, M11-334-2, G278, M11-347-4, M11-151-4, and Ag26 have the highest probability of a CO nova paternity.

Cataclysmic variables and related objects

NASA Technical Reports Server (NTRS)

Hack, Margherita; Ladous, Constanze; Jordan, Stuart D. (Editor); Thomas, Richard N. (Editor); Goldberg, Leo; Pecker, Jean-Claude

1993-01-01

This volume begins with an introductory chapter on general properties of cataclysmic variables. Chapters 2 through 5 of Part 1 are devoted to observations and interpretation of dwarf novae and nova-like stars. Chapters 6 through 10, Part 2, discuss the general observational properties of classical and recurrent novae, the theoretical models, and the characteristics and models for some well observed classical novae and recurrent novae. Chapters 11 through 14 of Part 3 are devoted to an overview of the observations of symbiotic stars, to a description of the various models proposed for explaining the symbiotic phenomenon, and to a discussion of a few selected objects, respectively. Chapter 15 briefly examines the many unsolved problems posed by the observations of the different classes of cataclysmic variables and symbiotic stars.

Infrared fiber optic materials

NASA Technical Reports Server (NTRS)

Feigelson, Robert S.

1987-01-01

The development of IR fiber optics for use in astronomical and other space applications is summarized. Candidate materials were sought for use in the 1 to 200 micron and the 200 to 1000 micron wavelength range. Synthesis and optical characterization were carried out on several of these materials in bulk form. And the fabrication of a few materials in single crystal fiber optic form were studied.

Independent Discovery of a Probable Luminous Nova in M81

NASA Astrophysics Data System (ADS)

Hornoch, K.; Kucakova, H.; Williams, S. C.; Henze, M.; Sala, G.; Jose, J.; Meusinger, H.; Darnley, M. J.; Kaur, A.; Hartmann, D. H.; Shafter, A. W.

2018-04-01

The M81 nova monitoring collaboration reports the independent discovery of a probable luminous nova in M81 on a co-added 4410-s unfiltered CCD frame taken on 2018 Apr. 9.044 UT with the 0.65-m telescope at Ondrejov.

Spectroscopic and Photometric Behaviour of Nova Cygni 1992 IN the First Nine Months Following Outburst

NASA Astrophysics Data System (ADS)

Chochol, D.; Hric, L.; Urban, Z.; Komzik, R.; Grygar, J.; Papousek, J.

1993-09-01

We present the results of UBV photometry and high dispersion 360-500 nm spectroscopy of Nova Cygni 1992 (= V 1974 Cyg), obtained between February 25 and November 9, 1992. Our data cover the early decline, transition and nebular stages of the evolution of the nova. We discuss the photometric and spectroscopic behaviour of the star during the first nine months after outburst and briefly compare our findings with the data already published by other authors. We have classified the nova as a fast one with t2,V = 16 d, t2,B = 23 d, and t3,V = 42 d, t3,B = 51 d. We have derived the absolute magnitudes of the nova at maximum to be M0,V = -7.67 and M0,B = -7.49. The latter value yields a mass of 0.83 Msun for the white dwarf component. The values of the distance modulus 12.23 and the colour excess EB-V = +0.32 correspond to a distance r = 1.77 kpc. We have found a period of 0.814 days by period analysis of photoelectric V data obtained before the nova declined 3m. During the nebular stage, forbidden lines of highly ionized neon were prominent, confirming the 0-Ne-Mg classification of the nova. The outburst of Nova Cygni 1992 was apparently caused by a super-Eddington thermonuclear runaway on the surface of an evolutionarily eroded O-Ne-Mg white dwarf.

Peripheral elastic and inelastic scattering of 17,18O on light targets at 12 MeV/nucleon

NASA Astrophysics Data System (ADS)

Carstoiu, F.; Al-Abdullah, T.; Gagliardi, C. A.; Trache, L.

2015-02-01

The elastic and inelastic scattering of 17,18O with light targets has been undertaken at 12 MeV/nucleon in order to determine the optical potentials needed for the transfer reaction 13C (17O ,18O )12C . Optical potentials in both incoming and outgoing channels have been determined in a single experiment. This transfer reaction was used to infer the direct capture rate to the 17F ( p ,γ)18Ne which is essential to estimate the production of 18F at stellar energies in ONe novae. We demonstrate the stability of the ANC method and OMP results using good quality elastic and inelastic scattering data with stable beams. The peripherality of our reaction is inferred from a semiclassical decomposition of the total scattering amplitude into barrier and internal barrier components. Comparison between elastic scattering of 17O , 18O and 16O projectiles is made.

An eLIMA model for the 67 s X-ray periodicity in CAL 83

NASA Astrophysics Data System (ADS)

Odendaal, A.; Meintjes, P. J.

2017-05-01

Supersoft X-ray sources (SSSs) are characterized by their low effective temperatures and high X-ray luminosities. The soft X-ray emission can be explained by hydrogen nuclear burning on the surface of a white dwarf (WD) accreting at an extremely high rate. A peculiar ˜67 s periodicity (P67) was previously discovered in the XMM-Newton light curves of the SSS CAL 83. P67 was detected in X-ray light curves spanning ˜9 yr, but exhibits variability of several seconds on time-scales as short as a few hours, and its properties are remarkably similar to those of dwarf nova oscillations (DNOs). DNOs are short time-scale modulations (≲1 min) often observed in dwarf novae during outburst. DNOs are explained by the well-established low-inertia magnetic accretor (LIMA) model. In this paper, we show that P67 and its associated period variability can be satisfactorily explained by an application of the LIMA model to the more 'extreme' environment in an SSS (eLIMA), contrary to another recent study attempting to explain P67 and its associated variability in terms of non-radial g-mode oscillations in the extended envelope of the rapidly accreting WD in CAL 83. In the eLIMA model, P67 originates in an equatorial belt in the WD envelope at the boundary with the inner accretion disc, with the belt weakly coupled to the WD core by an ˜105 G magnetic field. New optical light curves obtained with the Sutherland High-speed Optical Camera are also presented, exhibiting quasi-periodic modulations on time-scales of ˜1000 s, compatible with the eLIMA framework.

The Temporal Development of Dust Formation and Destruction in Nova Sagittarii 2015#2 (V5668 SGR): A Panchromatic Study

NASA Astrophysics Data System (ADS)

Gehrz, R. D.; Evans, A.; Woodward, C. E.; Helton, L. A.; Banerjee, D. P. K.; Srivastava, M. K.; Ashok, N. M.; Joshi, V.; Eyres, S. P. S.; Krautter, Joachim; Kuin, N. P. M.; Page, K. L.; Osborne, J. P.; Schwarz, G. J.; Shenoy, D. P.; Shore, S. N.; Starrfield, S. G.; Wagner, R. M.

2018-05-01

We present 5–28 μm SOFIA FORECAST spectroscopy complemented by panchromatic X-ray through infrared observations of the CO nova V5668 Sgr documenting the formation and destruction of dust during ∼500 days following outburst. Dust condensation commenced by 82 days after outburst at a temperature of ∼1090 K. The condensation temperature indicates that the condensate was amorphous carbon. There was a gradual decrease of the grain size and dust mass during the recovery phase. Absolute parameter values given here are for an assumed distance of 1.2 kpc. We conclude that the maximum mass of dust produced was 1.2 × 10‑7 M ⊙ if the dust was amorphous carbon. The average grain radius grew to a maximum of ∼2.9 μm at a temperature of ∼720 K around day 113 when the shell visual optical depth was τ v ∼ 5.4. Maximum grain growth was followed by a period of grain destruction. X-rays were detected with Swift from day 95 to beyond day 500. The Swift X-ray count rate due to the hot white dwarf peaked around day 220, when its spectrum was that of a kT = 35 eV blackbody. The temperature, together with the supersoft X-ray turn-on and turn-off times, suggests a white dwarf mass of ∼1.1 M ⊙. We show that the X-ray fluence was sufficient to destroy the dust. Our data show that the post-dust event X-ray brightening is not due to dust destruction, which certainly occurred, as the dust is optically thin to X-rays.

A SITELLE view of M31's central region - I. Calibrations and radial velocity catalogue of nearly 800 emission-line point-like sources

NASA Astrophysics Data System (ADS)

Martin, Thomas B.; Drissen, Laurent; Melchior, Anne-Laure

2018-01-01

We present a detailed description of the wavelength, astrometric and photometric calibration plan for SITELLE, the imaging Fourier transform spectrometer attached to the Canada-France-Hawaii telescope, based on observations of a red (647-685 nm) data cube of the central region (11 arcmin × 11 arcmin) of M 31. The first application, presented in this paper is a radial-velocity catalogue (with uncertainties of ∼2-6 km s-1) of nearly 800 emission-line point-like sources, including ∼450 new discoveries. Most of the sources are likely planetary nebulae, although we also detect five novae (having erupted in the first eight months of 2016) and one new supernova remnant candidate.

Development of reaction-sintered SiC mirror for space-borne optics

NASA Astrophysics Data System (ADS)

Yui, Yukari Y.; Kimura, Toshiyoshi; Tange, Yoshio

2017-11-01

We are developing high-strength reaction-sintered silicon carbide (RS-SiC) mirror as one of the new promising candidates for large-diameter space-borne optics. In order to observe earth surface or atmosphere with high spatial resolution from geostationary orbit, larger diameter primary mirrors of 1-2 m are required. One of the difficult problems to be solved to realize such optical system is to obtain as flat mirror surface as possible that ensures imaging performance in infrared - visible - ultraviolet wavelength region. This means that homogeneous nano-order surface flatness/roughness is required for the mirror. The high-strength RS-SiC developed and manufactured by TOSHIBA is one of the most excellent and feasible candidates for such purpose. Small RS-SiC plane sample mirrors have been manufactured and basic physical parameters and optical performances of them have been measured. We show the current state of the art of the RS-SiC mirror and the feasibility of a large-diameter RS-SiC mirror for space-borne optics.

Each Week, A Science Adventure. Settle Down in Front of the TV and See What NOVA Has for You This Time

ERIC Educational Resources Information Center

MOSAIC, 1975

1975-01-01

Describes how NOVA filmmakers developed a storyline about San Francisco Bay and captured it on film. Presents the criteria for topic selection by NOVA and the reception the program has had by viewing audiences. (GS)

ASASSN-18gb: Discovery of A Probable Nova in NGC 3109

NASA Astrophysics Data System (ADS)

Brimacombe, J.; Vallely, P.; Stanek, K. Z.; Kochanek, C. S.; Brown, J. S.; Shields, J.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Bersier, D.; Dong, Subo; Bose, S.; Chen, Ping; Stritzinger, M.; Holmbo, S.

2018-03-01

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from the quadruple 14-cm "Payne-Gaposchkin" telescope in Sutherland, South Africa, we discovered a new transient source, most likely a nova, in the Local Group galaxy NGC 3109.

NOVA, A BRIEF .....

ERIC Educational Resources Information Center

WHITING, RICHARD; AND OTHERS

NOVA IS AN EXPERIMENTAL, 6-YEAR JUNIOR-SENIOR HIGH SCHOOL. ASPECTS OF THE PROGRAM INCLUDE THE TRIMESTER SYSTEM, THE CONTINUOUS PROGRESS CURRICULUM, TEAM TEACHING, A CLASS SCHEDULE OF FOUR 70-MINUTE PERIODS PER WEEK, THE USE OF DATA-PROCESSING EQUIPMENT, AND MODERN INSTRUCTIONAL AIDS. NOVA IS ORGANIZED CAMPUS-STYLE WITH INDIVIDUAL BUILDINGS DEVOTED…

Dust formation in Nova Oph 2017 (TCP J17394608-2457555)

NASA Astrophysics Data System (ADS)

Joshi, Vishal; Banerjee, D. P. K.; Srivastava, Mudit

2017-06-01

Ongoing NIR observations of Nova Oph 2017 indicate the possible onset of dust formation in Nova Oph 2017. Monitoring in the JHKs bands shows a steady rise in the J-K color from around 1.4 on 5 June 2017 to 2.0 on 13 June 2017.

Liverpool Telescope Spectroscopy of the Nova Eruption from V392 Persei

NASA Astrophysics Data System (ADS)

Darnley, M. J.; Copperwheat, C. M.; Harvey, E. J.; Healy, M. W.

2018-05-01

Here we report Liverpool Telescope (LT; Steele et al. 2004) spectroscopy of the recent nova eruption (ATel #11588) from the known dwarf nova system V392 Per. A Fermi & gamma;-ray detection of the eruption has also been reported (ATel #11590) along with additional photometry (ATel #11594).

Olivier Chesneau's Work on Novae

NASA Astrophysics Data System (ADS)

Millour, F.; Lagadec, E.

2015-12-01

Olivier Chesneau founded a brand new field of observational astrophysics with his attempts to resolve the novae expanding fireball from the very first days of the explosion. With the images he could get, he showed that novae do indeed explode in an aspherical way, leading to a change of paradigm for the physics of these yet-poorly understood catastrophic systems. He also set the stage for a new way of estimating novae distances, by directly measuring the sky-size of the fireball and comparing it with spectroscopic scales, taking into account the tremendous effects of the fireball geometry.

Microstructures of Rare Silicate Stardust from Nova and Supernovae

NASA Technical Reports Server (NTRS)

Nguyen, A. N.; Keller, L. P.; Rahman, Z.; Messenger, S

2011-01-01

Most silicate stardust analyzed in the laboratory and observed around stellar environments derives from O-rich red giant and AGB stars [1,2]. Supernova (SN) silicates and oxides are comparatively rare, and fewer than 10 grains from no-va or binary star systems have been identified to date. Very little is known about dust formation in these stellar environments. Mineralogical studies of only three O-rich SN [3-5] and no nova grains have been performed. Here we report the microstructure and chemical makeup of two SN silicates and one nova grain.

Liquid Scintillator Production for the NOvA Experiment

DOE PAGES

Mufson, S.; Baugh, B.; Bower, C.; ...

2015-04-15

The NOvA collaboration blended and delivered 8.8 kt (2.72M gal) of liquid scintillator as the active detector medium to its near and far detectors. The composition of this scintillator was specifically developed to satisfy NOvA's performance requirements. A rigorous set of quality control procedures was put in place to verify that the incoming components and the blended scintillator met these requirements. The scintillator was blended commercially in Hammond, IN. The scintillator was shipped to the NOvA detectors using dedicated stainless steel tanker trailers cleaned to food grade.

Discovery of an old nova shell surrounding the cataclysmic variable V1315 Aql

NASA Astrophysics Data System (ADS)

Sahman, D. I.; Dhillon, V. S.; Littlefair, S. P.; Hallinan, G.

2018-04-01

Following our tentative discovery of a faint shell around V1315 Aql reported in Sahman et al. (2015), we undertook deep Hα imaging and intermediate-resolution spectroscopy of the shell. We find that the shell has its geometric centre located on V1315 Aql. The mass, spectral features and density of the shell are consistent with other nova shells, rather than planetary nebulae or supernova remnants. The radial velocity of the shell is consistent with the systemic velocity of V1315 Aql. We believe this evidence strongly suggests that the shell originates from an earlier nova event. This is the first nova shell discovered around a novalike, and supports the theory of nova-induced cycles in mass transfer rates (hibernation theory) first proposed by Shara et al. (1986).

Fermi Establishes Classical Novae as a Distinct Class of Gamma-ray Sources

NASA Technical Reports Server (NTRS)

Ackermann, M.; Ajello, M.; Albert, A.; Baldini, L.; Ballet, J.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.;

Fermi establishes classical novae as a distinct class of gamma-ray sources

DOE PAGES

Cheung, C. C.

2014-07-31

A classical nova results from runaway thermonuclear explosions on the surface of a white dwarf that accretes matter from a low-mass main-sequence stellar companion. In 2012 and 2013, three novae were detected in γ rays and stood in contrast to the first γ-ray detected nova V407 Cygni 2010, which belongs to a rare class of symbiotic binary systems. Despite likely differences in the compositions and masses of their white dwarf progenitors, the three classical novae are similarly characterized as soft spectrum transient γ-ray sources detected over 2-3 week durations. The γ-ray detections point to unexpected high-energy particle acceleration processes linkedmore » to the mass ejection from thermonuclear explosions in an unanticipated class of Galactic γ-ray sources.« less

Evolution of Nova-Dependent Splicing Regulation in the Brain

PubMed Central

Živin, Marko; Darnell, Robert B

2007-01-01

A large number of alternative exons are spliced with tissue-specific patterns, but little is known about how such patterns have evolved. Here, we study the conservation of the neuron-specific splicing factors Nova1 and Nova2 and of the alternatively spliced exons they regulate in mouse brain. Whereas Nova RNA binding domains are 94% identical across vertebrate species, Nova-dependent splicing silencer and enhancer elements (YCAY clusters) show much greater divergence, as less than 50% of mouse YCAY clusters are conserved at orthologous positions in the zebrafish genome. To study the relation between the evolution of tissue-specific splicing and YCAY clusters, we compared the brain-specific splicing of Nova-regulated exons in zebrafish, chicken, and mouse. The presence of YCAY clusters in lower vertebrates invariably predicted conservation of brain-specific splicing across species, whereas their absence in lower vertebrates correlated with a loss of alternative splicing. We hypothesize that evolution of Nova-regulated splicing in higher vertebrates proceeds mainly through changes in cis-acting elements, that tissue-specific splicing might in some cases evolve in a single step corresponding to evolution of a YCAY cluster, and that the conservation level of YCAY clusters relates to the functions encoded by the regulated RNAs. PMID:17937501

BK Lyncis: the oldest old nova and a Bellwether for cataclysmic variable evolution

NASA Astrophysics Data System (ADS)

Patterson, Joseph; Uthas, Helena; Kemp, Jonathan; de Miguel, Enrique; Krajci, Thomas; Foote, Jerry; Hambsch, Franz-Josef; Campbell, Tut; Roberts, George; Cejudo, David; Dvorak, Shawn; Vanmunster, Tonny; Koff, Robert; Skillman, David; Harvey, David; Martin, Brian; Rock, John; Boyd, David; Oksanen, Arto; Morelle, Etienne; Ulowetz, Joseph; Kroes, Anthony; Sabo, Richard; Jensen, Lasse

2013-09-01

We summarize the results of a 20-yr campaign to study the light curves of BK Lyn, a nova-like star strangely located below the 2 to 3 h orbital-period gap in the family of cataclysmic variables (CVs). Two apparent superhumps dominate the nightly light curves, with periods 4.6 per cent longer, and 3.0 per cent shorter, than the orbital period. The first appears to be associated with the star's brighter states (V ˜ 14), while the second appears to be present throughout and becomes very dominant in the low state (V ˜ 15.7). It is plausible that these arise, respectively, from a prograde apsidal precession and a retrograde nodal precession of the star's accretion disc. Starting in the year 2005, the star's light curve became indistinguishable from that of a dwarf nova - in particular, that of the ER UMa subclass. No such clear transition has ever been observed in a CV before. Reviewing all the star's oddities, we speculate: (a) BK Lyn is the remnant of the probable nova on 101 December 30, and (b) it has been fading ever since, but it has taken ˜2000 yr for the accretion rate to drop sufficiently to permit dwarf-nova eruptions. If such behaviour is common, it can explain other puzzles of CV evolution. One: why the ER UMa class even exists (because all members can be remnants of recent novae). Two: why ER UMa stars and short-period nova-likes are rare (because their lifetimes, which are essentially cooling times, are short). Three: why short-period novae all decline to luminosity states far above their true quiescence (because they are just getting started in their post-nova cooling). Four: why the orbital periods, accretion rates and white dwarf temperatures of short-period CVs are somewhat too large to arise purely from the effects of gravitational radiation (because the unexpectedly long interval of enhanced post-nova brightness boosts the mean mass-transfer rate). And maybe even five: why very old, post-period-bounce CVs are hard to find (because the higher mass-loss rates have `burned them out'). These are substantial rewards in return for one investment of hypothesis: that the second parameter in CV evolution, besides orbital period, is time since the last classical-nova eruption.

Optical disk processing of solar images.

NASA Astrophysics Data System (ADS)

Title, A.; Tarbell, T.

The current generation of space and ground-based experiments in solar physics produces many megabyte-sized image data arrays. Optical disk technology is the leading candidate for convenient analysis, distribution, and archiving of these data. The authors have been developing data analysis procedures which use both analog and digital optical disks for the study of solar phenomena.

A search for optical pulsations from GX 1+4 at H-alpha

NASA Technical Reports Server (NTRS)

Krzeminski, W.; Priedhorsky, W. C.

1978-01-01

H-alpha observations of the binary-star candidate for the slowly pulsating hard X-ray source GX 1+4 are reported which were undertaken to search for pulsations in the H-alpha flux that are synchronous with the X-ray period of about 2 min. No significant periodic variation of the candidate star was detected in the frequency band searched. Three-sigma upper limits of 1.7% (sinusoidal pulse shape) and 0.7% (X-ray pulse shape) are set for the pulsed fraction of the H-alpha flux. It is noted that because of possible diffusion from a cloud that is optically thick to Balmer radiation, the observed lack of pulsations in the H-alpha flux need not compromise the identification of GX 1+4 with the candidate star.

MIRIADS: miniature infrared imaging applications development system description and operation

NASA Astrophysics Data System (ADS)

Baxter, Christopher R.; Massie, Mark A.; McCarley, Paul L.; Couture, Michael E.

2001-10-01

A cooperative effort between the U.S. Air Force Research Laboratory, Nova Research, Inc., the Raytheon Infrared Operations (RIO) and Optics 1, Inc. has successfully produced a miniature infrared camera system that offers significant real-time signal and image processing capabilities by virtue of its modular design. This paper will present an operational overview of the system as well as results from initial testing of the 'Modular Infrared Imaging Applications Development System' (MIRIADS) configured as a missile early-warning detection system. The MIRIADS device can operate virtually any infrared focal plane array (FPA) that currently exists. Programmable on-board logic applies user-defined processing functions to the real-time digital image data for a variety of functions. Daughterboards may be plugged onto the system to expand the digital and analog processing capabilities of the system. A unique full hemispherical infrared fisheye optical system designed and produced by Optics 1, Inc. is utilized by the MIRIADS in a missile warning application to demonstrate the flexibility of the overall system to be applied to a variety of current and future AFRL missions.

Improving the {sup 33}S(p,{gamma}){sup 34}Cl Reaction Rate for Models of Classical Nova Explosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parikh, A.; Faestermann, Th.; Kruecken, R.

2011-10-28

Reduced uncertainty in the thermonuclear rate of the {sup 33}S(p,{gamma}){sup 34}Cl reaction would help to improve our understanding of nucleosynthesis in classical nova explosions. At present, models are generally in concordance with observations that nuclei up to roughly the calcium region may be produced in these explosive phenomena; better knowledge of this rate would help with the quantitative interpretation of nova observations over the S-Ca mass region, and contribute towards the firm establishment of a nucleosynthetic endpoint. As well, models find that the ejecta of nova explosions on massive oxygen-neon white dwarfs may contain as much as 150 times themore » solar abundance of {sup 33}S. This characteristic isotopic signature of a nova explosion could possibly be observed through the analysis of microscopic grains formed in the environment surrounding a nova and later embedded within primitive meteorites. An improved {sup 33}S(p,{gamma}){sup 34}Cl rate (the principal destruction mechanism for {sup 33}S in novae) would help to ensure a robust model prediction for the amount of {sup 33}S that may be produced. Finally, constraining this rate could confirm or rule out the decay of an isomeric state of {sup 34}Cl(E{sub x} = 146 keV, t{sub 1/2} = 32 m) as a source for observable gamma-rays from novae. We have performed several complementary experiments dedicated to improving our knowledge of the {sup 33}S(p,{gamma}){sup 34}Cl rate, using both indirect methods (measurement of the {sup 34}S({sup 3}He,t){sup 34}Cl and {sup 33}S({sup 3}He,d){sup 34}Cl reactions with the Munich Q3D spectrograph) and direct methods (in normal kinematics at CENPA, University of Washington, and in inverse kinematics with the DRAGON recoil mass separator at TRIUMF). Our results will be used with nova models to facilitate comparisons of model predictions with present and future nova observables.« less

SALT high-resolution spectroscopy of nova PNV J15384000-4744500

NASA Astrophysics Data System (ADS)

Aydi, E.; Buckley, D. A. H.; Mohamed, S.; Whitelock, P. A.

2018-06-01

We report on high-resolution spectroscopy of PNV J15384000-4744500 which was reported as a possible nova by Rob Kaufman (Bright, Victoria, Australia; CBAT follow-up: http://www.cbat.eps.harvard.edu/unconf/followups/J15384000-4744500.html) and confirmed as a classical nova by F. Walter (ATel #11681).

15 CFR 904.102 - Procedures upon receipt of a NOVA.

Code of Federal Regulations, 2010 CFR

2010-01-01

... (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE GENERAL REGULATIONS CIVIL PROCEDURES Civil Penalties § 904.102 Procedures upon receipt of a NOVA. (a) The respondent has 30 days from... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Procedures upon receipt of a NOVA. 904...

15 CFR 904.102 - Procedures upon receipt of a NOVA.

Code of Federal Regulations, 2011 CFR

2011-01-01

... (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE GENERAL REGULATIONS CIVIL PROCEDURES Civil Penalties § 904.102 Procedures upon receipt of a NOVA. (a) The respondent has 30 days from... 15 Commerce and Foreign Trade 3 2011-01-01 2011-01-01 false Procedures upon receipt of a NOVA. 904...

The Potential of NovaNET Communications for Education and Instruction.

ERIC Educational Resources Information Center

Steinberg, Esther R.

Intended to suggest ways of implementing the potential of NovaNet beyond its current applications, this report begins with an overview of current educational applications of telecommunications systems. It is noted that NovaNET is not only a successful computer system for presenting instructional courseware, but that it also supports…

Art Education, Romantic Idealism, and Work: Comparing Ruskin's Ideas to Those Found in Nineteenth Century Nova Scotia.

ERIC Educational Resources Information Center

Amburgy, Patricia; Soucy, Donald

1989-01-01

Examines the relationship between romantic idealism and vocational goals of art education in nineteenth-century Nova Scotia, Canada. Compares these ideas with those of John Ruskin concerning art and morality. Discusses the views of the Nova Scotian educators relative to issues of contemporary art education. (KO)

Detection of Highly-Absorbed X-rays from Nova Mus 2018 with Swift

NASA Astrophysics Data System (ADS)

Nelson, Thomas; Kuin, Paul; Mukai, Koji; Page, Kim; Chomiuk, Laura; Kawash, Adam; Sokoloski, J. L.; Linford, Justin; Rupen, Michael P.; Mioduszewski, Amy

2018-03-01

We report the detection of X-rays from Nova Mus 2018 with the Swift XRT instrument. We have been carrying out weekly monitoring of the nova with Swift since its discovery on 2018 Jan 15 (see ATel #11220), and observations up to 2018 Feb 24 yielded X-ray non-detections.

Measurement of key resonance states for the P 30 ( p , γ ) S 31 reaction rate, and the production of intermediate-mass elements in nova explosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kankainen, A.; Woods, P. J.; Schatz, H.

2017-06-01

We report the first experimental constraints on spectroscopic factors and strengths of key resonances in the P-30(p, gamma)S-31 reaction critical for determining the production of intermediate-mass elements up to Ca in nova ejecta. The P-30(d,n)S-31 reaction was studied in inverse kinematics using the GRETINA gamma-ray array to measure the angle-integrated cross-sections of states above the proton threshold. In general, negative parity states are found to be most strongly produced but the absolute values of spectroscopic factors are typically an order of magnitude lower than predicted by the shell-model calculations employing WBP Hamiltonian for the negative-parity states. The results clearly indicatemore » the dominance of a single 3/2(-) resonance state at 196 keV in the region of nova burning T approximate to 0.10-0.17 GM, well within the region of interest for nova nucleosynthesis. Hydrodynamic simulations of nova explosions have been performed to demonstrate the effect on the composition of nova ejecta.« less

π0 mass reconstruction in NOvA Far Detector.

NASA Astrophysics Data System (ADS)

Edayath, Sijith

2017-01-01

NOvA is a long-baseline neutrino oscillation experiment with functionally identical, segmented, tracking calorimeter Near and Far detectors. The detectors lie 14.6 mrad off-axis from the Fermilab NuMI beam, with a well-defined peak in neutrino energy at 2 GeV. The absolute calibration of the energy scale of the detectors is a major systematic uncertainty in long-baseline oscillation search in NOvA. Neutrino detectors make use of some standard candles for absolute energy calibration. Stopping muon energy distributions, Michel electron energy distributions, and invariant π0 mass are among them. In this talk, we cover NOvA's use of a new method to identify π0 with cosmic origins in the NOvA Far Detector. We employ a computer vision based particle identifier using convolutional neural networks (CVN) to identify π0s, complementing an existing strategy to identify π0 from the neutrino beam using more traditional methods in the Near Detector. Registered for PhD at Cochin University of Science and Technology, India and doing research in NOvA experiment at Fermilab.

Measurement of key resonance states for the 30P (p , γ)31S reaction rate, and the production of intermediate-mass elements in nova explosions

NASA Astrophysics Data System (ADS)

Kankainen, A.; Woods, P. J.; Schatz, H.; Poxon-Pearson, T.; Doherty, D. T.; Bader, V.; Baugher, T.; Bazin, D.; Brown, B. A.; Browne, J.; Estrade, A.; Gade, A.; José, J.; Kontos, A.; Langer, C.; Lotay, G.; Meisel, Z.; Montes, F.; Noji, S.; Nunes, F.; Perdikakis, G.; Pereira, J.; Recchia, F.; Redpath, T.; Stroberg, R.; Scott, M.; Seweryniak, D.; Stevens, J.; Weisshaar, D.; Wimmer, K.; Zegers, R.

2017-06-01

We report the first experimental constraints on spectroscopic factors and strengths of key resonances in the 30P (p , γ)31S reaction critical for determining the production of intermediate-mass elements up to Ca in nova ejecta. The 30P (d , n)31S reaction was studied in inverse kinematics using the GRETINA γ-ray array to measure the angle-integrated cross-sections of states above the proton threshold. In general, negative-parity states are found to be most strongly produced but the absolute values of spectroscopic factors are typically an order of magnitude lower than predicted by the shell-model calculations employing WBP Hamiltonian for the negative-parity states. The results clearly indicate the dominance of a single 3 /2- resonance state at 196 keV in the region of nova burning T ≈ 0.10- 0.17 GK, well within the region of interest for nova nucleosynthesis. Hydrodynamic simulations of nova explosions have been performed to demonstrate the effect on the composition of nova ejecta.

X ray and gamma ray emission from classical nova outbursts

NASA Technical Reports Server (NTRS)

Truran, James W.; Starrfield, Sumner; Sparks, Warren M.

1992-01-01

The outbursts of classical novae are now recognized to be consequences of thermonuclear runaways proceeding in accreted hydrogen-rich shells on white dwarfs in close binary systems. For the conditions that are known to exist in these environments, it is expected that soft x-rays can be emitted, and indeed x-rays were detected from a number of novae. The circumstances for which we expect novae to produce significant x-ray fluxes and provide estimates of the luminosities and effective temperatures are described. It is also known that at the high temperatures that are known to be achieved in this explosive hydrogen-burning environment, significant production of both Na-22 and Al-26 will occur. In this context, we identify the conditions for which gamma-ray emission may be expected to result from nova outbursts.

Constraints on the neutrino flux in NOvA using the near detector data

DOE PAGES

Maan, Kuldeep K.

2016-12-19

NOvA, a long-baseline neutrino oscillation experiment at Fermilab, is designed to measure electron-neutrino appearance and muon-neutrino disappearance in the NuMI beam. NOvA comprises of two finely segmented liquid scintillator detectors at 14 mrad off-axis in the NuMI beam. An accurate prediction of the neutrino flux is needed for precision oscillation and cross-section measurements. Data from the hadron-production experiments and, importantly, from the NOvA Near Detector provide powerful constraints on the muon-neutrino and electron-neutrino fluxes. In particular, the measurement of the neutrino-electron elastic scattering provides an in situ constraint on the absolute flux. Lastly, this poster presents the data-driven predictions ofmore » the NOvA muonneutrino and electron-neutrino flux, and outlines future improvements in the flux determination.« less

Efficacy and patient satisfaction after NovaSure and Minerva endometrial ablation for treating abnormal uterine bleeding: a retrospective comparative study.

PubMed

Scordalakes, Constantine; delRosario, Robert; Shimer, Andrew; Stankiewicz, Russell

2018-01-01

Compare amenorrhea rate, menstrual symptoms, patient satisfaction, and adverse events in women who underwent endometrial ablation with the NovaSure versus the Minerva radiofrequency ablation systems. We surveyed 189 premenopausal women (mean 40.8±6.2 years old) who underwent endometrial ablation for abnormal uterine bleeding using the NovaSure (n=97) or Minerva (n=92) systems, at four private US gynecology clinics, and whose procedure date was after July 2015 with follow-up ≥3 months. Women were surveyed an average of 11.3±3.9 months (range 137-532 days) after ablation. The subject-reported amenorrhea rate was 52% higher in NovaSure subjects than Minerva subjects (64% and 42%, respectively; p =0.004). Age and bleeding cyclicity did not affect amenorrhea rate in either group. Normal-to-no bleeding was reported by >90% of subjects after either treatment. NovaSure was significantly more effective than Minerva at reducing pad/tampon use in women with any residual bleeding (2.4±5.2 items/day versus 4.7±5.5 items/day, p =0.049). NovaSure was significantly more effective than Minerva at reducing premenstrual syndrome (PMS) symptoms ( p =0.019) and menstrual pain ( p =0.003), and more NovaSure subjects (94%) than Minerva subjects (78%) were satisfied with clinical outcomes ( p =0.003). Adverse events did not differ by treatment; three women in each group progressed to hysterectomy. While overall bleeding reduction in premenopausal women with abnormal uterine bleeding was excellent with either endometrial ablation system, NovaSure treatment resulted in a higher patient-reported 1-year amenorrhea rate, and women with residual bleeding used fewer pads and tampons than Minerva-treated women. Additionally, NovaSure subjects reported better menstrual-related life quality and PMS symptom alleviation, and greater satisfaction with outcomes than Minerva-treated women.

Exquisite Nova Light Curves from the Solar Mass Ejection Imager (SMEI)

NASA Astrophysics Data System (ADS)

Hounsell, R.; Bode, M. F.; Hick, P. P.; Buffington, A.; Jackson, B. V.; Clover, J. M.; Shafter, A. W.; Darnley, M. J.; Mawson, N. R.; Steele, I. A.; Evans, A.; Eyres, S. P. S.; O'Brien, T. J.

2010-11-01

We present light curves of three classical novae (CNe; KT Eridani, V598 Puppis, V1280 Scorpii) and one recurrent nova (RS Ophiuchi) derived from data obtained by the Solar Mass Ejection Imager (SMEI) on board the Coriolis satellite. SMEI provides near complete skymap coverage with precision visible-light photometry at 102 minute cadence. The light curves derived from these skymaps offer unprecedented temporal resolution around, and especially before, maximum light, a phase of the eruption normally not covered by ground-based observations. They allow us to explore fundamental parameters of individual objects including the epoch of the initial explosion, the reality and duration of any pre-maximum halt (found in all three fast novae in our sample), the presence of secondary maxima, speed of decline of the initial light curve, plus precise timing of the onset of dust formation (in V1280 Sco) leading to estimation of the bolometric luminosity, white dwarf mass, and object distance. For KT Eri, Liverpool Telescope SkyCamT data confirm important features of the SMEI light curve and overall our results add weight to the proposed similarities of this object to recurrent rather than to CNe. In RS Oph, comparison with hard X-ray data from the 2006 outburst implies that the onset of the outburst coincides with extensive high-velocity mass loss. It is also noted that two of the four novae we have detected (V598 Pup and KT Eri) were only discovered by ground-based observers weeks or months after maximum light, yet these novae reached peak magnitudes of 3.46 and 5.42, respectively. This emphasizes the fact that many bright novae per year are still overlooked, particularly those of the very fast speed class. Coupled with its ability to observe novae in detail even when relatively close to the Sun in the sky, we estimate that as many as five novae per year may be detectable by SMEI.

Multi-wavelength studies of Redback and Black Widow pulsars

NASA Astrophysics Data System (ADS)

Mignani, Roberto; Salvetti, David; Pallanca, Cristina; Marelli, Martino; De Luca, Andrea; Belfiore, Andrea Mario

2016-07-01

The unexpected Fermi discovery of more than 70 gamma-ray milli-second pulsars (MSPs) outside globular clusters, spurred the scientific interest on these objects, and opened new horizons in MSP astronomy and on the study of the evolution of neutron stars in compact binary systems, including the ablation process of the companion star in the so-called Black Widow (BW) and Redback (RB) systems. It is thought that an important fraction of the tens of unidentified pulsar-like Fermi sources at high latitude are MSPs, yet unidentified, owing to their extremely elusive radio emission. As shown in a few recent cases, optical observations have been instrumental to spot binary MSP candidates through the discovery of periodic modulations in the flux of their putative companions. In this contribution, we report on the recent follow-ups of several candidate binary MSPs carried out with optical and X-ray facilities, e.g. GROND and XMM-Newton, Swift. This program already lead to identification of the Fermi source 3FGL 2036.6-5618 as candidate RB system, through the detection of periodic (orbital) modulation of its X/optical flux (Salvetti et al. 2015).

The Robo-AO KOI survey: laser adaptive optics imaging of every Kepler exoplanet candidate

NASA Astrophysics Data System (ADS)

Ziegler, Carl; Law, Nicholas M.; Baranec, Christoph; Morton, Tim; Riddle, Reed; Atkinson, Dani; Nofi, Larissa

2016-07-01

The Robo-AO Kepler Planetary Candidate Survey is observing every Kepler planet candidate host star (KOI) with laser adaptive optics imaging to hunt for blended nearby stars which may be physically associated companions. With the unparalleled efficiency provided by the first fully robotic adaptive optics system, we perform the critical search for nearby stars (0.15" to 4.0" separation with contrasts up to 6 magnitudes) that dilute the observed planetary transit signal, contributing to inaccurate planetary characteristics or astrophysical false positives. We present 3313 high resolution observations of Kepler planetary hosts from 2012-2015, discovering 479 nearby stars. We measure an overall nearby star probability rate of 14.5+/-0.8%. With this large data set, we are uniquely able to explore broad correlations between multiple star systems and the properties of the planets which they host, providing insight into the formation and evolution of planetary systems in our galaxy. Several KOIs of particular interest will be discussed, including possible quadruple star systems hosting planets and updated properties for possible rocky planets orbiting with in their star's habitable zone.

The Robo-AO KOI Survey: Laser Adaptive Optics Imaging of Every Kepler Exoplanet Candidate

NASA Astrophysics Data System (ADS)

Ziegler, Carl; Law, Nicholas M.; Baranec, Christoph; Morton, Tim; Riddle, Reed L.

2016-01-01

The Robo-AO Kepler Planetary Candidate Survey is observing every Kepler planet candidate host star (KOI) with laser adaptive optics imaging to hunt for blended nearby stars which may be physically associated companions. With the unparalleled efficiency provided by the first fully robotic adaptive optics system, we perform the critical search for nearby stars (0.15" to 4.0" separation with contrasts up to 6 magnitudes) that pollute the observed planetary transit signal, contributing to inaccurate planetary characteristics or astrophysical false positives. We present approximately 3300 high resolution observations of Kepler planetary hosts from 2012-2015, with ~500 observed nearby stars. We measure an overall nearby star probability rate of 16.2±0.8%. With this large dataset, we are uniquely able to explore broad correlations between multiple star systems and the properties of the planets which they host. We then use these clues for insight into the formation and evolution of these exotic systems. Several KOIs of particular interest will be discussed, including possible quadruple star systems hosting planets and updated properties for possible rocky planets orbiting in the habitable zone.

How Galileo and Kepler Countered Aristotle's Cosmological Errors

NASA Astrophysics Data System (ADS)

Gingerich, O.

2009-08-01

Aristotle made two major common sense assumptions that ultimately had to be refuted to open the way to modern science. One was the dichotomy between celestial and terrestrial. The other was the separation of astronomy from physics. Galileo, particularly with his examination of the moon in the Sidereus nuncius, was a pioneer in destroying the first assumption, while Kepler, whose Astronomia nova was subtitled ``based on causes, or celestial physics,'' broke the stranglehold of the second. The importance of these fundamental contributions toward establishing the nature of modern science, which paved the way for Isaac Newton, is often overshadowed by their more specific contributions in optics or mechanics.

IOTA: recent science and technology

NASA Astrophysics Data System (ADS)

Schloerb, F. Peter; Berger, J.-P.; Carleton, N. P.; Hagenauer, P.; Kern, P. Y.; Labeye, P. R.; Lacasse, M. G.; Malbet, F.; Millan-Gabet, R.; Monnier, J. D.; Pearlman, M. R.; Pedretti, E.; Rousselet-Perraut, K.; Ragland, S. D.; Schuller, P. A.; Traub, W. A.; Wallace, G.

2006-06-01

We present a brief review of recent scientific and technical advances at the Infrared Optical Telescope Array (IOTA). IOTA is a long-baseline interferometer located atop Mount Hopkins, Arizona. Recent work has emphasized the use of the three-telescope interferometer completed in 2002. We report on results obtained on a range of scientific targets, including AGB stars, Herbig AeBe Stars, binary stars, and the recent outburst of the recurrent nova RS Oph. We report the completion of a new spectrometer which allows visibility measurements at several high spectral resolution channels simultaneously. Finally, it is our sad duty to report that IOTA will be closed this year.

Discovery of Classical Nova in NGC2403 : P60-NGC2403-090314

NASA Astrophysics Data System (ADS)

Kasliwal, M. M.; Cenko, S. B.; Ofek, E. O.; Quimby, R.; Rau, A.; Caltech, Kulkarni, S. R.

2009-03-01

On UT 2009 Mar 14.160, P60-FasTING (Palomar 60-inch Fast Transients In Nearby Galaxies) discovered an optical transient in NGC2403 at RA(J2000) = 07:36:35.00, DEC(J2000)=+65:40:20.8, offset from the nucleus by 101.0"W, 252.0"N. P60-NGC2403-090314 had a brightness of g = 20.6 +/- 0.1 at discovery. At peak, on Mar 15.147, the apparent g = 19.6 corresponded to Mg = -8.2, at the distance of NGC2403. It was not detected by P60 to g > 21.8 on Mar 2.164.

Discovery of Possible Bright Nova in NGC891 : P60-NGC891-080813

NASA Astrophysics Data System (ADS)

Kasliwal, M. M.; Cenko, S. B.; Rau, A.; Ofek, E. O.; Quimby, R.; Kulkarni, S. R.

2008-08-01

On UT 2008 Aug 13.45, P60-FasTING (Palomar 60-inch Fast Transients In Nearby Galaxies) discovered an optical transient at RA(J2000)=02:22:32.70, DEC(J2000)=42:21:56.1 in the field of NGC891. P60-NGC891-080813 is offset from the nucleus of NGC891 by 8"W,59"N. The light curve thus far is g>22 (Jul 30.48), g=21.2 (Aug 13.45), g=21.0 (Aug 14.32), g=21.0 (Aug 15.32). Photometric calibration is wrt USNO-B1 and uncertain by 0.2 mags.

SOFIA: A Promising Resource for Future Nova Studies

NASA Astrophysics Data System (ADS)

Helton, L. A.; Sofia Science Team

2014-12-01

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a 2.5-m telescope carried on board a Boeing 747-SP aircraft. Optimized for observations from infrared through sub-mm wavelengths, SOFIA observes from an altitude of 37,000 - 45,000 feet, above 99% of the atmospheric water vapor. The Observatory's complement of instruments possesses a broad range of capabilities, many of which are especially well suited for observations of classical novae, recurrent novae, and other cataclysmic variables. Here we present a selection of the instruments available on board SOFIA that may prove to be very useful for future novae studies.

Recent Results on SNRs and PWNe from the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Hays, Elizabeth

2010-01-01

a) Symbiotic Binary System: White dwarf + red giant system. b) Nova: White dwarf builds up mass envelope to the point of thermonuclear fusion. c) Dramatic increase in visual magnitude. d) Recurrent Nova? e) Hints but no strong confirmation of previous nova f) Pre-nova activity: 1) White dwarf shows ongoing variability at level of several in magnitude. 2) V407 Cyg companion is a Mira star showing variability at level of several in magnitude. g) Origin of the gamma rays? 1) Strong shock propagating into dense medium around giant star land stellar wind. 2) Pion decay or electron processes?

Machine Tests Optical Fibers In Flexure

NASA Technical Reports Server (NTRS)

Darejeh, Hadi; Thomas, Henry; Delcher, Ray

1993-01-01

Machine repeatedly flexes single optical fiber or cable or bundle of optical fibers at low temperature. Liquid nitrogen surrounds specimen as it is bent back and forth by motion of piston. Machine inexpensive to build and operate. Tests under repeatable conditions so candidate fibers, cables, and bundles evaluated for general robustness before subjected to expensive shock and vibration tests.

Cannibal Stars Cause Giant Explosions in Fornax Cluster Galaxy

NASA Astrophysics Data System (ADS)

2000-07-01

The VLT Observes Most Remote Novae Ever Seen About 70 million years ago, when dinosaurs were still walking on the Earth, a series of violent thermo-nuclear explosions took place in a distant galaxy. After a very long travel across vast reaches of virtually empty space (70 million light-years, or ~ 7 x 10 20 km), dim light carrying the message about these events has finally reached us. It was recorded by the ESO Very Large Telescope (VLT) at the Paranal Observatory (Chile) during an observing programme by a group of Italian astronomers [1]. The subsequent analysis has shown that the observers witnessed the most distant nova outbursts ever seen . They were caused by "stellar cannibalism" in binary systems in which one relatively cool star loses matter to its smaller and hotter companion. An instability results that leads to the ignition of a "hydrogen bomb" on the surface of the receiving star. The "Stella Nova" Phenomenon A stellar outburst of the type now observed with the VLT is referred to as a "Stella Nova" ("new star" in Latin), or just "Nova" . Novae caused by explosions in binary stars in our home galaxy, the Milky Way system, are relatively frequent and about every second or third year one of them is bright enough to be easily visible with the naked eye. For our ancestors, who had no means to see the faint binary star before the explosion, it looked as if a new star had been born in the sky, hence the name. The most common nova explosion occurs in a binary stellar system in which a white dwarf (a very dense and hot, compact star with a mass comparable to that of the Sun and a size like the Earth) accretes hydrogen from a cooler and larger red dwarf star [2]. As the hydrogen collects on the surface of the white dwarf star, it becomes progressively hotter until a thermonuclear explosion is ignited at the bottom of the collected gas. A huge amount of energy is released and causes a million-fold increase in the brightness of the binary system within a few hours. After reaching maximum light within some days or weeks, it begins to fade as the hydrogen supply is exhausted and blown into space. The processed material is ejected at high speeds, up to ~1000 km/sec, and may later be visible as an expanding shell of emitting gas. Altogether, the tremendous flash of light involves the release of about 10 45 ergs in a few weeks, or about as much energy as our Sun produces in 10,000 years. Supernovae explosions that completely destroy heavier stars at the end of their lives are even more powerful. However, in contrast to supernovae and despite the colossal energy production, the progenitor of a nova is not destroyed during the explosion. Some time after an outburst, transfer of hydrogen from the companion star begins anew, and the process repeats itself with explosions taking place about once every 100,000 years. The nova star will finally die of "old age" when the cool companion has been completely cannibalized. Novae as Distance Indicators Due to their exceptional luminosity, novae can be used as powerful beacons that allow relative distances to different types of galaxies to be measured. The measurement is based on the assumption that novae of the same type are intrinsically equally bright, together with the physical law that states that an object's observed brightness decreases with the square of the distance to the observer. Thus, if we observe that a nova in a certain galaxy is one million times fainter than a nearby one, we know that it must be one thousand times more distant. In addition, observations of novae in other galaxies shed light on the history of formation of their stars. Despite their scientific importance, surveys of novae in distant, rich clusters of galaxies have not been very popular among astronomers. Major reasons are probably the inherent observational difficulties and the comparatively low rates of discovery. In the past, with 4-m class telescopes, tens of hours of monitoring of several galaxies have indeed been necessary to detect a few distant novae [3]. VLT observations of NGC 1316 in the Fornax Cluster ESO PR Photo 18a/00 ESO PR Photo 18a/00 [Preview - JPEG: 400 x 448 pix - 28k] [Normal - JPEG: 800 x 895 pix - 136k] [Full-Res - JPEG: 1941 x 2172 pix - 904k] Caption : Colour composite photo of the central area of NGC 1316 , a giant elliptical galaxy in the Fornax cluster of galaxies. Many dark dust clouds and lanes are visible. Some of the star-like objects in the field are globular clusters of stars that belong to the galaxy. It is based on CCD exposures, obtained with the 8.2-m VLT/ANTU telescope and the FORS-1 multi-mode instrument through B (blue), V (green-yellow) and I (here rendered as red) filters, respectively. The "pyramids" above and below the bright centre of the galaxy and the vertical lines at some of the brighter stars are caused by overexposure ("CCD bleeding"). The field measures 6.8 x 6.8 arcmin 2 , with 0.2 arcsec/pixel. The image quality of this composite is about 0.9 arcsec. North is up and East is left. NGC 1316 is a giant "dusty" galaxy ( PR Photo 18a/00 ), located in the Fornax cluster seen in the southern constellation of that name ("The Oven"). This galaxy is of special interest in connection with current attempts to establish an accurate distance scale in the Universe. In 1980 and 1981, NGC 1316 was the host of two supernovae of type Ia , a class of object that is widely used as a "cosmological standard candle" to determine the distance to very distant galaxies, cf. ESO PR 21/98. A precise measurement of the distance to NGC 1316 may therefore provide an independent calibration of the intrinsic brightness of these supernovae. The new observations were performed during 8 nights distributed over the period from January 9 to 19, 2000. They were made in service mode at the 8.2-m VLT/ANTU telescope with the FORS-1 multi-mode instrument, using a 2k x 2k CCD camera with 0.2 arcsec pixels and a field of 6.8 x 6.8 arcmin 2. The exposures lasted 20 min and were carried out with three optical filters (B, V and I). The most distant Novae observed so far ESO PR Photo 18b/00 ESO PR Photo 18b/00 [Preview - JPEG: 400 x 452 pix - 83k] [Normal - JPEG: 800 x 904 pix - 224k] ESO PR Photo 18c/00 ESO PR Photo 18c/00 [Preview - JPEG: 400 x 458 pix - 54k] [Normal - JPEG: 800 x 916 pix - 272k] Caption : Images of two of the novae in NGC 1316 that were discovered during the observational programme described in this Press Release. Both composites show the blue images (B-filter) obtained on January 9 (upper left), 12 (upper right), 15 (lower left) and 19 (lower right), 2000, respectively. The decline of the brightness of the objects is obvious. An analysis of the images that were obtained in blue light (B-filter) resulted in the detection of four novae. They were identified because of the typical change of brightness over the observation period, cf. PR Photos 18b-c/00 , as well as their measured colours. Although the time-consuming reduction of the data and the subsequent astrophysical interpretation is still in progress, the astronomers are already now very satisfied with the outcome. In particular, no less than four novae were detected in a single giant galaxy within only 11 days . This implies a rate of approximately 100 novae/year in NGC 1316, or about 3 times larger than the rate estimated for the Milky Way galaxy. This may (at least partly) be due to the fact that NGC 1316 is of a different type and contains more stars than our own galaxy. The novae in NGC 1316 are quite faint, of about magnitude 24 and decreasing towards 25-26 during the period of observation. This corresponds to nearly 100 million times fainter than what can be seen with the naked eye. The corresponding distance to NGC 1316 is found to be about 70 million light-years . Moreover, the discovery of four novae in one galaxy in the Fornax cluster was possible with only 3 hours of observing time per filter. This clearly shows that the new generation of 8-m class telescopes like the VLT, equipped with the new and large detectors, is able to greatly improve the efficiency of this type of astronomical investigations (by a factor of 10 or more) , as compared to previous searches with 4-m telescopes. The road is now open for exhaustive searches for novae in remote galaxies, with all the resulting benefits, also for the accurate determination of the extragalactic distance scale. Notes [1]: The group consists of Massimo Della Valle (Osservatorio Astrofisico di Arcetri, Firenze, Italy), Roberto Gilmozzi and Rodolfo Viezzer (both ESO). [2]: A graphical illustration of the nova phenomenon can be found at this website. [3]: For example, in 1987, Canadian astronomers Christopher Pritchet and Sidney van den Bergh , in an heroic tour de force with the 4-m Canada-France-Hawaii telescope, found 9 novae after 56 hours of monitoring of 3 giant elliptical galaxies in the Virgo cluster of galaxies.

Downy mildew disease of New England aster (Symphyotrichum novae-angliae) caused by Basidiophora simplex in New York

USDA-ARS?s Scientific Manuscript database

The native perennial New England aster (Symphyotrichum novae-angliae; syn.=Aster novae-anglicae) is ubiquitous throughout most of the United States, as they self-seed and are well-adapted to many environments. New England asters are valued for their prominent dense clusters of purple flowers that at...

Innovation and Skills Development in the Rural Voluntary Sector in Nova Scotia

ERIC Educational Resources Information Center

Canadian Rural Partnership, 2002

2002-01-01

This report is a summary of discussions that took place at the Rural Voluntary Sector Leaders' Dialogue, entitled "Innovation and Skills Development in the Rural Voluntary Sector in Nova Scotia", held in Truro, Nova Scotia on September 20, 2002. Many of the discussions took place in brainstorming sessions at which no limits were placed…

Results of Statewide TerraNova Testing, Fall 1998.

ERIC Educational Resources Information Center

La Marca, Paul M.

This summary provides key findings about state, district, and school level performance on the TerraNova examinations (CTB/McGraw Hill) in Nevada in 1998-1999. The TerraNova tests are used to assess students in grades 4, 8, and 10 as stipulated by Nevada law. Within this summary, a description of performance as measured by national percentile…

Analysis of Craniocardiac Malformations in Xenopus using Optical Coherence Tomography

PubMed Central

Deniz, Engin; Jonas, Stephan; Hooper, Michael; N. Griffin, John; Choma, Michael A.; Khokha, Mustafa K.

2017-01-01

Birth defects affect 3% of children in the United States. Among the birth defects, congenital heart disease and craniofacial malformations are major causes of mortality and morbidity. Unfortunately, the genetic mechanisms underlying craniocardiac malformations remain largely uncharacterized. To address this, human genomic studies are identifying sequence variations in patients, resulting in numerous candidate genes. However, the molecular mechanisms of pathogenesis for most candidate genes are unknown. Therefore, there is a need for functional analyses in rapid and efficient animal models of human disease. Here, we coupled the frog Xenopus tropicalis with Optical Coherence Tomography (OCT) to create a fast and efficient system for testing craniocardiac candidate genes. OCT can image cross-sections of microscopic structures in vivo at resolutions approaching histology. Here, we identify optimal OCT imaging planes to visualize and quantitate Xenopus heart and facial structures establishing normative data. Next we evaluate known human congenital heart diseases: cardiomyopathy and heterotaxy. Finally, we examine craniofacial defects by a known human teratogen, cyclopamine. We recapitulate human phenotypes readily and quantify the functional and structural defects. Using this approach, we can quickly test human craniocardiac candidate genes for phenocopy as a critical first step towards understanding disease mechanisms of the candidate genes. PMID:28195132

A method for selecting M dwarfs with an increased likelihood of unresolved ultracool companionship

NASA Astrophysics Data System (ADS)

Cook, N. J.; Pinfield, D. J.; Marocco, F.; Burningham, B.; Jones, H. R. A.; Frith, J.; Zhong, J.; Luo, A. L.; Qi, Z. X.; Lucas, P. W.; Gromadzki, M.; Day-Jones, A. C.; Kurtev, R. G.; Guo, Y. X.; Wang, Y. F.; Bai, Y.; Yi, Z. P.; Smart, R. L.

2016-04-01

Locating ultracool companions to M dwarfs is important for constraining low-mass formation models, the measurement of substellar dynamical masses and radii, and for testing ultracool evolutionary models. We present an optimized method for identifying M dwarfs which may have unresolved ultracool companions. We construct a catalogue of 440 694 M dwarf candidates, from Wide-Field Infrared Survey Explorer, Two Micron All-Sky Survey and Sloan Digital Sky Survey, based on optical- and near-infrared colours and reduced proper motion. With strict reddening, photometric and quality constraints we isolate a subsample of 36 898 M dwarfs and search for possible mid-infrared M dwarf + ultracool dwarf candidates by comparing M dwarfs which have similar optical/near-infrared colours (chosen for their sensitivity to effective temperature and metallicity). We present 1082 M dwarf + ultracool dwarf candidates for follow-up. Using simulated ultracool dwarf companions to M dwarfs, we estimate that the occurrence of unresolved ultracool companions amongst our M dwarf + ultracool dwarf candidates should be at least four times the average for our full M dwarf catalogue. We discuss possible contamination and bias and predict yields of candidates based on our simulations.

Robotic laser adaptive optics imaging of 715 Kepler exoplanet candidates using Robo-AO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Law, Nicholas M.; Ziegler, Carl; Morton, Tim

2014-08-10

The Robo-AO Kepler Planetary Candidate Survey is observing every Kepler planet candidate host star with laser adaptive optics imaging to search for blended nearby stars, which may be physically associated companions and/or responsible for transit false positives. In this paper, we present the results from the 2012 observing season, searching for stars close to 715 Kepler planet candidate hosts. We find 53 companions, 43 of which are new discoveries. We detail the Robo-AO survey data reduction methods including a method of using the large ensemble of target observations as mutual point-spread-function references, along with a new automated companion-detection algorithm designedmore » for large adaptive optics surveys. Our survey is sensitive to objects from ≈0.''15 to 2.''5 separation, with magnitude differences up to Δm ≈ 6. We measure an overall nearby-star probability for Kepler planet candidates of 7.4% ± 1.0%, and calculate the effects of each detected nearby star on the Kepler-measured planetary radius. We discuss several Kepler Objects of Interest (KOIs) of particular interest, including KOI-191 and KOI-1151, which are both multi-planet systems with detected stellar companions whose unusual planetary system architecture might be best explained if they are 'coincident multiple' systems, with several transiting planets shared between the two stars. Finally, we find 98% confidence evidence that short-period giant planets are two to three times more likely than longer-period planets to be found in wide stellar binaries.« less

Distant clusters of galaxies in the 2XMM/SDSS footprint: follow-up observations with the LBT

NASA Astrophysics Data System (ADS)

Rabitz, A.; Lamer, G.; Schwope, A.; Takey, A.

2017-11-01

Context. Galaxy clusters at high redshift are important to test cosmological models and models for the growth of structure. They are difficult to find in wide-angle optical surveys, however, leaving dedicated follow-up of X-ray selected candidates as one promising identification route. Aims: We aim to increase the number of galaxy clusters beyond the SDSS-limit, z 0.75. Methods: We compiled a list of extended X-ray sources from the 2XMMp catalogue within the footprint of the Sloan Digital Sky Survey. Fields without optical counterpart were selected for further investigation. Deep optical imaging and follow-up spectroscopy were obtained with the Large Binocular Telescope, Arizona (LBT), of those candidates not known to the literature. Results: From initially 19 candidates, selected by visually screening X-ray images of 478 XMM-Newton observations and the corresponding SDSS images, 6 clusters were found in the literature. Imaging data through r,z filters were obtained for the remaining candidates, and 7 were chosen for multi-object (MOS) spectroscopy. Spectroscopic redshifts, optical magnitudes, and X-ray parameters (flux, temperature, and luminosity) are presented for the clusters with spectroscopic redshifts. The distant clusters studied here constitute one additional redshift bin for studies of the LX-T relation, which does not seem to evolve from high to low redshifts. Conclusions: The selection method of distant galaxy clusters presented here was highly successful. It is based solely on archival optical (SDSS) and X-ray (XMM-Newton) data. Out of 19 selected candidates, 6 of the 7 candidates selected for spectroscopic follow-up were verified as distant clusters, a further candidate is most likely a group of galaxies at z 1.21. Out of the remaining 12 candidates, 6 were known previously as galaxy clusters, one object is a likely X-ray emission from an AGN radio jet, and for 5 we see no clear evidence for them to be high-redshift galaxy clusters. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: the University of Arizona on behalf of the Arizona Board of Regents; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, The Leibniz Institute for Astrophysics Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia - http://www.lbto.org/for-investigators.htmlThe catalogue, similar to Table A.1, is also available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/607/A56

An Emerging Wine Region in Nova Scotia, Canada: Terroir Trials and Tribulations

NASA Astrophysics Data System (ADS)

Cameron, B. I.; Ketter, B. S.; Karakis, S.

2012-12-01

Nova Scotia, strategically located on Canada's east coast, is an emerging wine region, whose distinctive wines are garnering international acclaim. Nova Scotia has a long and rich tradition of growing grapes for wine dating back as far as 1611. Nova Scotia's mesoclimates, glacial soils, and proximity to the Atlantic Ocean form a complex alliance to create a unique and expressive terroir. Tidal Bay is a new appellation wine for Nova Scotia stylistically defined as a fresh, crisp and high-acid blend of white grapes. There are four main wine-growing regions in Nova Scotia, all influenced by the warming effects of the Bay of Fundy and Atlantic Ocean: Malagash Peninsula, Annapolis Valley, Bear River Valley and the South Shore. Nova Scotia currently has 14 producing wineries with many more in the development stage. Nova Scotia grape growers not only have had success developing mature and consistent hybrids, but in recent years several vinifera have flourished in this cool climate area. The white hybrids include L'Acadie Blanc, New York Muscat, Seyval Blanc, and Vidal Blanc. The white vinifera include chardonnay, riesling, pinot gris, and sauvignon blanc. Red hybrids are Baco Noir, Leon Millet, Lucie Kuhlmann, and Marechal Foch, whereas the only red vinifera is pinot noir. Nova Scotia has nearly perfect climatic conditions for making world class icewines and sparkling wines. A preliminary GIS analysis of climate, topographic, geology and soil data helps to define Nova Scotia's terroir. Annual precipiatation varies from 10 to 21.6 cm/year with a vast majority of the wineries located in regions with the lowest rainfall. Daily average temperature ranges from 5.5 to 7.5°C, degree growing days above 5°C from 1382 to 1991, and mean August temperature from 15.6 to 19.3 °C. Wineries cluster in the warmest regions based on these temperature measures to assist grape ripening. Soils in these diverse wine regions can range from silty, sandy and clay loams to more gravel-rich sandy loams. In the Gaspereaux Valley, a sub-valley of the Annapolis Valley, relatively fertile silty and clay loams dominate on the south-facing slope, but well-drained, gravel-rich glacial soils on the north-facing slope impart a complex and mineral flavor profile to the wines. Detailed soil profiles from select vineyards along with studies of soil texture and chemistry highlight differences in terroirs in the four wine regions. This terroir study assists the expanding, but young wine industry in Nova Scotia to ideally match grape variety to vineyard block.

Safety and Effectiveness of NovaSure® Endometrial Ablation After Placement of Essure® Micro-Inserts

PubMed Central

Price, Pamela; Burkhart, Jamie; Johnson, Jamie

2012-01-01

Abstract Objective: In-office NovaSure® after Essure® is a clinical paradigm for which physicians are seeking information. A PubMed search (July 2011) revealed no peer-reviewed articles describing this treatment sequence. To address the paucity of data on this topic, patients who had undergone Essure followed by NovaSure in a private practice office between July 1, 2008 and December 31, 2009 were evaluated. The objective was to evaluate safety and feasibility of in-office NovaSure after Essure, and to determine if the effectiveness of either procedure was altered by this treatment sequence. Design: This was a retrospective cohort study of 117 women (ages 24–52). Methods: Patients underwent Essure followed by NovaSure in two in-office sessions, separated by a median of 14 days. All patients had menorrhagia and desired permanent sterilization. A postprocedure patient questionnaire was administered to assess satisfaction and perceived effectiveness. Results: Among patients who underwent Essure followed by NovaSure, 83/117 (71%) returned for a 3-month hysterosalpingogram (HSG). Satisfactory placement and tubal occlusion were noted in 79/83 (95%) of these patients. Amenorrhea or spotting was observed in 72/97 (74%) of patients, 22/97 (23%) reported a satisfactory decrease in menstrual flow, and 3/97 (3%) reported ablation failure. Essure followed by NovaSure did not decrease the effectiveness of either procedure, and no adverse events were attributed to the combination of the two procedures. Patients reported high levels of satisfaction with both procedures. Conclusions: In women seeking permanent birth control and menorrhagia reduction, in-office Essure followed by NovaSure appeared to be safe, effective, and associated with high patient satisfaction. (J GYNECOL SURG 28:1) PMID:24761128

A Search for Novae in the M31 Globular Cluster System

NASA Astrophysics Data System (ADS)

Tomaney, Austin; Crotts, Arlin; Shafter, Allen

1992-12-01

Roughly 10% of all low mass X-ray binaries (LMXB's, neutron star - low mass sequence close binaries) are found in Galactic globular clusters (GC's) implying an enhancement per unit mass of roughly three orders of magnitude of these objects inside GC's compared with the field. Fabian, Pringle and Rees (1975) suggested that these lcose binary systems may be formed via tidal capture in the dense cluster cores. Similar arguments are likely to apply to nova systems which are cataclysmic variables (CV's) consisting of a close binary white dwarf - low mass main sequence star. Supporting arguments include the discovery over the past century of two novae in Galactic GC's, and the existence of low luminosity X-ray sources in GC's (Hertz and Grindlay 1983). In addition, surveys for novae in M31 indicate that the specfic density of novae in its bulge is an order of magnitude higher than its disk and it has been argued by Ciardullo et al. (1987) that novae in the bulge of M31 have been spawned inside GC's and subsequently ejected into the field. We present the results of a search (during 1988 and 1989) of over 200 M31 GC's using a fibre multi-object spectrograph to detect Hα emission, a signature of a potential nova eruptions. No eruptions were detected over an effective survey time of one year for the entire known M31 GC system. Although the lower mass of white dwarfs compared with neutron stars implies their effective capture cross section is smaller, we argue that since novae occur much more frequently on high mass white dwarfs this survey provides a sensitive test to the number of high mass CV's in GC's and their enhancement is unlikely to be as high as LMXB's.

Copernicus observations of Nova Cygni 1975

NASA Technical Reports Server (NTRS)

Jenkins, E. B.; Snow, T. P.; Upson, W. L.; Anderson, R.; Starrfield, S. G.; Gallagher, J. S.; Friedjung, M.; Linsky, J. L.; Henry, R. C.; Moos, H. W.

1977-01-01

Near-ultraviolet radiation from Nova Cygni 1975 was detected by the Copernicus satellite on five occasions from 1975 September 1 to 1975 September 9. The nova was not seen in the UV after this date. The principal result was the observation of a broad emission feature from the Mg II doublet at 2800 A. The absence of strong UV radiation at shorter wavelengths suggests that these lines are produced by collisional excitation in the outer layers of an expanding shell with electron temperature of approximately 4000 K. The absence of observed emission lines from highly ionized species indicates that the amount of material with log T between 4.4 and 5.7 is less than 0.001 times that which produces the Mg II emission. The continuum flux in the near-UV decreased as the nova evolved, showing that the total luminosity decreased as the nova faded in the visible.

HITS-CLIP yields genome-wide insights into brain alternative RNA processing

NASA Astrophysics Data System (ADS)

Licatalosi, Donny D.; Mele, Aldo; Fak, John J.; Ule, Jernej; Kayikci, Melis; Chi, Sung Wook; Clark, Tyson A.; Schweitzer, Anthony C.; Blume, John E.; Wang, Xuning; Darnell, Jennifer C.; Darnell, Robert B.

2008-11-01

Protein-RNA interactions have critical roles in all aspects of gene expression. However, applying biochemical methods to understand such interactions in living tissues has been challenging. Here we develop a genome-wide means of mapping protein-RNA binding sites in vivo, by high-throughput sequencing of RNA isolated by crosslinking immunoprecipitation (HITS-CLIP). HITS-CLIP analysis of the neuron-specific splicing factor Nova revealed extremely reproducible RNA-binding maps in multiple mouse brains. These maps provide genome-wide in vivo biochemical footprints confirming the previous prediction that the position of Nova binding determines the outcome of alternative splicing; moreover, they are sufficiently powerful to predict Nova action de novo. HITS-CLIP revealed a large number of Nova-RNA interactions in 3' untranslated regions, leading to the discovery that Nova regulates alternative polyadenylation in the brain. HITS-CLIP, therefore, provides a robust, unbiased means to identify functional protein-RNA interactions in vivo.

New sidescan sonar and gravity evidence that the Nova-Canton Trough is a fracture zone

NASA Astrophysics Data System (ADS)

Joseph, Devorah; Taylor, Brian; Shor, Alexander N.

1992-05-01

A 1990 sidescan sonar survey in the eastern region of the Nova-Canton Trough mapped 138°-striking abyssal-hill fabric trending into 70°-striking trough structures. The location and angle of intersection of the abyssal hills with the eastern Nova-Canton Trough effectively disprove a spreading-center origin of this feature. Free-air gravity anomalies derived from satellite altimetry data show continuity, across the Line Islands, of the Nova-Canton Trough with the Clipperton Fracture Zone. The Canton-Clipperton trend is copolar, about a pole at 30°S, 152°W, with other coeval Pacific-Farallon fracture-zone segments, from the Pau to Marquesas fracture zones. This copolarity leads us to postulate a Pacific-Farallon spreading pattern for the magnetic quiet zone region north and east of the Manihiki Plateau, with the Nova-Canton Trough originating as a transform fault in this system.

Integration of the Super Nova early warning system with the NOvA Trigger

DOE Office of Scientific and Technical Information (OSTI.GOV)

Habig, Alec; Zirnstein, Jan

The NOvA experiment, with a baseline of 810km, samples Fermilab’s upgraded NuMI beam with a Near Detector on-site and a Far Detector (FD) at Ash River, MN, to observe oscillations of muon neutrinos. The 344,064 liquid scintillator-filled cells of the 14 kton FD provide high granularity of a large detector mass and enable us to also study non-accelerator based neutrinos with our Data Driven Trigger framework. This paper will focus on the real time integration of the SNEWS with the NOvA Trigger where we have set up an XML-RPC based messaging system to inject the SNEWS signal directly into ourmore » trigger. In conclusion, this presents a departure from the E-Mail based notification mechanism used by SNEWS in the past and allows NOvA more control over propagation and transmission timing.« less

Integration of the Super Nova early warning system with the NOvA Trigger

DOE PAGES

Habig, Alec; Zirnstein, Jan

2015-12-23

The NOvA experiment, with a baseline of 810km, samples Fermilab’s upgraded NuMI beam with a Near Detector on-site and a Far Detector (FD) at Ash River, MN, to observe oscillations of muon neutrinos. The 344,064 liquid scintillator-filled cells of the 14 kton FD provide high granularity of a large detector mass and enable us to also study non-accelerator based neutrinos with our Data Driven Trigger framework. This paper will focus on the real time integration of the SNEWS with the NOvA Trigger where we have set up an XML-RPC based messaging system to inject the SNEWS signal directly into ourmore » trigger. In conclusion, this presents a departure from the E-Mail based notification mechanism used by SNEWS in the past and allows NOvA more control over propagation and transmission timing.« less

Accretion disk dynamics in X-ray binaries

NASA Astrophysics Data System (ADS)

Peris, Charith Srian

Accreting X-ray binaries consist of a normal star which orbits a compact object with the former transferring matter onto the later via an accretion disk. These accretion disks emit radiation across the entire electromagnetic spectrum. This thesis exploits two regions of the spectrum, exploring the (1) inner disk regions of an accreting black hole binary, GRS1915+105, using X-ray spectral analysis and (2) the outer accretion disks of a set of neutron star and black hole binaries using Doppler Tomography applied on optical observations. X-ray spectral analysis of black hole binary GRS1915+105: GRS1915+105 stands out as an exceptional black hole primarily due to the wild variability exhibited by about half of its X-ray observations. This study focused on the steady X-ray observations of the source, which were found to exhibit significant curvature in the harder coronal component within the RXTE/PCA band-pass. The roughly constant inner-disk radius seen in a majority of the steady-soft observations is strongly reminiscent of canonical soft state black-hole binaries. Remarkably, the steady-hard observations show the presence of growing truncation in the inner-disk. A majority of the steady observations of GRS1915+105 map to the states observed in canonical black hole binaries which suggests that within the complexity of this source is a simpler underlying basis of states. Optical tomography of X-ray binary systems: Doppler tomography was applied to the strong line features present in the optical spectra of X-ray binaries in order to determine the geometric structure of the systems' emitting regions. The point where the accretion stream hits the disk, also referred to as the "hotspot'', is clearly identified in the neutron star system V691 CrA and the black hole system Nova Muscae 1991. Evidence for stream-disk overflows exist in both systems, consistent with relatively high accretion rates. In contrast, V926 Sco does not show evidence for the presence of a hotspot which is consistent with its lower accretion state. The donor stars in V691 CrA and Nova Muscae 1991 were also detected.

The SuperNova Integral Field Spectrograph

NASA Astrophysics Data System (ADS)

Aldering, Gregory S.; Supernova Factory, Nearby

2007-05-01

The SuperNova Integral Field Spectrograph (SNIFS) is operated at the University of Hawaii 2.2 meter telescope on Mauna Kea by the Nearby Supernova Factory. The IFU has a 6x6 arcsecond field of view, and the combined blue and red channels simultaneously cover the full optical (320-1000 nm) spectral range. SNIFS was designed to allow spectrophotometry of supernovae under both photometric and non-photometric conditions. SNIFS is operated entirely remotely, in a quasi-automated mode, from as nearby as Hilo, Hawaii and as far away as Paris, France. Being mounted at the south bent Cassegrain focus of the UH 2.2-m, SNIFS is always available, either for regular Nearby Supernova Factory observations, or any of a range of programs conducted by astronomers at the University of Hawaii Institute for Astronomy. We illustrate some of the unique features of SNIFS and some of the science programs that have been undertaken using it. This work is supported in part by the Director, Office of Science, Office of High Energy and Nuclear Physics, of the U.S. Department of Energy under Contracts No. DE-FG0-92ER40704, by a grant from the Gordon & Betty Moore Foundation, and in France by CNRS/IN2P3, CNRS/INSU and PNC.

Testing the relativistic Doppler boost hypothesis for supermassive black hole binary candidates

NASA Astrophysics Data System (ADS)

Charisi, Maria; Haiman, Zoltán; Schiminovich, David; D'Orazio, Daniel J.

2018-06-01

Supermassive black hole binaries (SMBHBs) should be common in galactic nuclei as a result of frequent galaxy mergers. Recently, a large sample of sub-parsec SMBHB candidates was identified as bright periodically variable quasars in optical surveys. If the observed periodicity corresponds to the redshifted binary orbital period, the inferred orbital velocities are relativistic (v/c ≈ 0.1). The optical and ultraviolet (UV) luminosities are expected to arise from gas bound to the individual BHs, and would be modulated by the relativistic Doppler effect. The optical and UV light curves should vary in tandem with relative amplitudes which depend on the respective spectral slopes. We constructed a control sample of 42 quasars with aperiodic variability, to test whether this Doppler colour signature can be distinguished from intrinsic chromatic variability. We found that the Doppler signature can arise by chance in ˜20 per cent (˜37 per cent) of quasars in the nUV (fUV) band. These probabilities reflect the limited quality of the control sample and represent upper limits on how frequently quasars mimic the Doppler brightness+colour variations. We performed separate tests on the periodic quasar candidates, and found that for the majority, the Doppler boost hypothesis requires an unusually steep UV spectrum or an unexpectedly large BH mass and orbital velocity. We conclude that at most approximately one-third of these periodic candidates can harbor Doppler-modulated SMBHBs.

Using the information of cosmic rays to predict influence epidemic

NASA Astrophysics Data System (ADS)

Yu, Z. D.

1985-08-01

A correlation between the incidence of influenza pandemics and increased cosmic ray activity is made. A correlation is also made between the occurrence of these pandemics and the appearance of bright novae, e.g., Nova Eta Car. Four indices based on increased cosmic ray activity and novae are proposed to predict future influenza pandemics and viral antigenic shifts.

Using the information of cosmic rays to predict influence epidemic

NASA Technical Reports Server (NTRS)

Yu, Z. D.

1985-01-01

A correlation between the incidence of influenza pandemics and increased cosmic ray activity is made. A correlation is also made between the occurrence of these pandemics and the appearance of bright novae, e.g., Nova Eta Car. Four indices based on increased cosmic ray activity and novae are proposed to predict future influenza pandemics and viral antigenic shifts.

NovaNET 2008-09 Evaluation. Impact Evaluation. E&R Report No. 09.36

ERIC Educational Resources Information Center

Bulgakov-Cook, Dina

2010-01-01

NovaNET is a technology-based teacher-facilitated educational approach used at schools to support students at risk of not meeting graduation requirements to accrue credits in a variety of subjects. NovaNET contributes to the WCPSS goal of closing achievement gaps and creating opportunities for all students to graduate on time. In 2008-09, 38…

Beyond an Operational Reserve

DTIC Science & Technology

2013-05-01

Background, and Bibliography, (New York: Nova Science Pub Inc, 2002), 72. 46 components, the first in 1993 and later in 1997, to discuss the...8 George Bennett, The United States Army: Issues, Background, and Bibliography, (New York: Nova Science Pub Inc, 2002), 71...George Bennett, The United States Army: Issues, Background, and Bibliography, (New York: Nova Science Pub Inc, 2002), 74. 11 Angelo, M. Reserve

New insights from a statistical analysis of IUE spectra of dwarf novae and nova-like stars. I - Inclination effects in lines and continua

NASA Technical Reports Server (NTRS)

La Dous, Constanze

1991-01-01

IUE observations of dwarf novae at maximum at quiescence and novalike objects at the high brightness state are analyzed for effects of the inclination angle on the emitted continuum and line radiation. A clear pattern in the continuum flux distribution is exhibited only by dwarf novae at maximum where some 80 percent of the non-double-eclipsing systems show essentially identical distributions. This result is not in disagreement with theoretical expectations. All classes of objects exhibit a clear, but in each case different, dependence of the line radiation on the inclination angle.

Are supernovae recorded in indigenous astronomical traditions?

NASA Astrophysics Data System (ADS)

Hamacher, Duane W.

2014-07-01

Novae and supernovae are rare astronomical events that would have had an influence on the skywatching peoples who witnessed them. Although several bright novae/supernovae have been visible during recorded human history, there are many proposed but no confirmed accounts of supernovae in indigenous oral traditions or material culture. Criteria are established for confirming novae/supernovae in oral traditions and material culture, and claims from around the world are discussed to determine if they meet these criteria. Aboriginal Australian traditions are explored for possible descriptions of novae/supernovae. Although representations of supernovae may exist in Aboriginal traditions, there are currently no confirmed accounts of supernovae in Indigenous Australian oral or material traditions.

Evaluating local food programs: the case of Select Nova Scotia.

PubMed

Knight, Andrew J

2013-02-01

This study evaluated the effectiveness of the buy local food program Select Nova Scotia; a government program with the goal to increase awareness and consumption of Nova Scotia produced and processed agri-food products by Nova Scotians and visitors. The evaluation methodology was based on prior evaluation resources and local food consumer research. Data were gathered through a web panel survey; 877 respondents completed the survey in June 2010. The results suggest that the program is reaching a wider audience than just those predisposed to local food initiatives. In addition, awareness of Select Nova was related to perceptions of local benefits and barriers, as well as purchase motivation and behavior. Respondents who were aware of Select Nova Scotia rated societal benefits as more important and viewed location and price as less of a barrier; they were also more likely to be highly motivated to purchase local foods. This study also informs results found in previous consumer research studies and identifies marketing opportunities to enhance the effectiveness of local food programs. The results suggest that societal benefits might be used as a way to differentiate products with similar attributes. Copyright © 2012 Elsevier Ltd. All rights reserved.

X-ray Modeling of Classical Novae

NASA Astrophysics Data System (ADS)

Nemeth, Peter

2010-01-01

It has been observed and theoretically supported in the last decade that the peak of the spectral energy distribution of classical novae gradually shifts to higher energies at constant bolometric luminosity after a nova event. For this reason, comprehensive evolutionary studies require spectral analysis in multiple spectral bands. After a nova explosion, the white dwarf can maintain stable surface hydrogen burning, the duration of which strongly correlates with the white dwarf mass. During this stage the peak of the luminosity is in the soft X-ray band (15 - 60 Angstroms). By extending the modeling range of TLUSTY/SYNSPEC, I analyse the luminosity and abundance evolution of classical novae. Model atoms required for this work were built using atomic data from NIST/ASD and TOPBASE. The accurate but incomplete set of energy levels and radiative transitions in NIST were completed with calculated data from TOPBASE. Synthetic spectra were then compared to observed data to derive stellar parameters. I show the capabilities and validity of this project on the example of V4743 Sgr. This nova was observed with both Chandra and XMM-Newton observatories and has already been modeled by several scientific groups (PHOENIX, TMAP).

Toxicity assessment in marine sediment for the Terra Nova environmental effects monitoring program (1997-2010)

NASA Astrophysics Data System (ADS)

Whiteway, Sandra A.; Paine, Michael D.; Wells, Trudy A.; DeBlois, Elisabeth M.; Kilgour, Bruce W.; Tracy, Ellen; Crowley, Roger D.; Williams, Urban P.; Janes, G. Gregory

2014-12-01

This paper discusses toxicity test results on sediments from the Terra Nova offshore oil development. The Terra Nova Field is located on the Grand Banks approximately 350 km southeast of Newfoundland (Canada). The amphipod (Rhepoxynius abronius) survival and solid phase luminescent bacteria (Vibrio fischeri, or Microtox) assays were conducted on sediment samples collected from approximately 50 stations per program year around Terra Nova during baseline (1997), prior to drilling, and in 2000, 2001, 2002, 2004, 2006, 2008 and 2010 after drilling began. The frequency of toxic responses in the amphipod toxicity test was low. Of the ten stations that were toxic in environmental effects monitoring (EEM) years, only one (station 30(FE)) was toxic in more than one year and could be directly attributed to Terra Nova project activities. In contrast, 65 (18%) of 364 EEM samples were toxic to Microtox. Microtox toxicity in EEM years was not related to distance from Terra Nova drill centres or concentrations of >C10-C21 hydrocarbons or barium, the primary constituents of the synthetic-based drill muds used at Terra Nova. Of the variables tested, fines and strontium levels showed the strongest (positive) correlations with toxicity. Neither fines nor strontium levels were affected by drill cuttings discharge at Terra Nova, except at station 30(FE) (and that station was not toxic to Microtox). Benthic macro-invertebrate abundance, richness and diversity were greater in toxic than in non-toxic sediments. Therefore, Microtox responses indicating toxicity were associated with positive biological responses in the field. This result may have been an indirect function of the increased abundance of most invertebrate taxa in less sandy sediments with higher gravel content, where fines and strontium levels and, consequently, toxicity to Microtox were high; or chemical substances released by biodegradation of organic matter, where invertebrates are abundant, may be toxic to Microtox. Given the lack of association between Microtox results and discharge from Terra Nova, coupled with the confounding effects of other variables, the usefulness of Microtox toxicity tests within the context of environmental monitoring for the Terra Nova and, potentially, other offshore oil operations needs to be questioned. The amphipod toxicity tests showed that sediments in the vicinity of discharges of synthetic-based drilling mud cuttings are rarely toxic.

OPTICAL SPECTROSCOPIC OBSERVATIONS OF GAMMA-RAY BLAZAR CANDIDATES. V. TNG, KPNO, AND OAN OBSERVATIONS OF BLAZAR CANDIDATES OF UNCERTAIN TYPE IN THE NORTHERN HEMISPHERE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Álvarez Crespo, N.; Massaro, F.; Masetti, N.

The extragalactic γ-ray sky is dominated by emission from blazars, a peculiar class of active galactic nuclei. Many of the γ-ray sources included in the Fermi-Large Area Telescope Third Source catalog (3FGL) are classified as blazar candidates of uncertain type (BCUs) because there are no optical spectra available in the literature to confirm their nature. In 2013, we started a spectroscopic campaign to look for the optical counterparts of the BCUs and of the unidentified γ-ray sources to confirm their blazar nature. Whenever possible we also determine their redshifts. Here, we present the results of the observations carried out inmore » the northern hemisphere in 2013 and 2014 at the Telescopio Nazionale Galileo, Kitt Peak National Observatory, and Observatorio Astronómico Nacional in San Pedro Mártir. In this paper, we describe the optical spectra of 25 sources. We confirmed that all of the 15 BCUs observed in our campaign and included in our sample are blazars and we estimated the redshifts for three of them. In addition, we present the spectra for three sources classified as BL Lacs in the literature but with no optical spectra available to date. We found that one of them is a quasar (QSO) at a redshift of z = 0.208 and the other two are BL Lacs. Moreover, we also present seven new spectra for known blazars listed in the Roma-BZCAT that have an uncertain redshift or are classified as BL Lac candidates. We found that one of them, 5BZB J0724+2621, is a “changing look” blazar. According to the spectrum available in the literature, it was classified as a BL Lac, but in our observation we clearly detected a broad emission line that led us to classify this source as a QSO at z = 1.17.« less

Revisiting Optical Tidal Disruption Events with iPTF16axa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hung, T.; Gezari, S.; Blagorodnova, N.

We report the discovery by the intermediate Palomar Transient Factory (iPTF) of a candidate tidal disruption event (TDE) iPTF16axa at z = 0.108 and present its broadband photometric and spectroscopic evolution from three months of follow-up observations with ground-based telescopes and Swift. The light curve is well fitted with a t -5/3 decay, and we constrain the rise time to peak to be <49 rest-frame days after disruption, which is roughly consistent with the fallback timescale expected for the ~5 × 10 6 M ⊙ black hole inferred from the stellar velocity dispersion of the host galaxy. The UV and optical spectral energy distribution is well described by a constant blackbody temperature of T ~ 3 × 10 4 K over the monitoring period, with an observed peak luminosity of 1.1 × 10 44 erg s -1. The optical spectra are characterized by a strong blue continuum and broad He ii and Hα lines, which are characteristic of TDEs. We compare the photometric and spectroscopic signatures of iPTF16axa with 11 TDE candidates in the literature with well-sampled optical light curves. Based on a single-temperature fit to the optical and near-UV photometry, most of these TDE candidates have peak luminosities confined between log(L [erg s -1]) = 43.4–44.4, with constant temperatures of a few ×104 K during their power-law declines, implying blackbody radii on the order of 10 times the tidal disruption radius, that decrease monotonically with time. For TDE candidates with hydrogen and helium emission, the high helium-to-hydrogen ratios suggest that the emission arises from high-density gas, where nebular arguments break down. In conclusion, we find no correlation between the peak luminosity and the black hole mass, contrary to the expectations for TDEs to havemore » $$\\dot{M}\\propto {M}_{\\mathrm{BH}}^{-1/2}$$.« less

Revisiting Optical Tidal Disruption Events with iPTF16axa

DOE PAGES

Hung, T.; Gezari, S.; Blagorodnova, N.; ...

2017-06-08

We report the discovery by the intermediate Palomar Transient Factory (iPTF) of a candidate tidal disruption event (TDE) iPTF16axa at z = 0.108 and present its broadband photometric and spectroscopic evolution from three months of follow-up observations with ground-based telescopes and Swift. The light curve is well fitted with a t -5/3 decay, and we constrain the rise time to peak to be <49 rest-frame days after disruption, which is roughly consistent with the fallback timescale expected for the ~5 × 10 6 M ⊙ black hole inferred from the stellar velocity dispersion of the host galaxy. The UV and optical spectral energy distribution is well described by a constant blackbody temperature of T ~ 3 × 10 4 K over the monitoring period, with an observed peak luminosity of 1.1 × 10 44 erg s -1. The optical spectra are characterized by a strong blue continuum and broad He ii and Hα lines, which are characteristic of TDEs. We compare the photometric and spectroscopic signatures of iPTF16axa with 11 TDE candidates in the literature with well-sampled optical light curves. Based on a single-temperature fit to the optical and near-UV photometry, most of these TDE candidates have peak luminosities confined between log(L [erg s -1]) = 43.4–44.4, with constant temperatures of a few ×104 K during their power-law declines, implying blackbody radii on the order of 10 times the tidal disruption radius, that decrease monotonically with time. For TDE candidates with hydrogen and helium emission, the high helium-to-hydrogen ratios suggest that the emission arises from high-density gas, where nebular arguments break down. In conclusion, we find no correlation between the peak luminosity and the black hole mass, contrary to the expectations for TDEs to havemore » $$\\dot{M}\\propto {M}_{\\mathrm{BH}}^{-1/2}$$.« less

Revisiting Optical Tidal Disruption Events with iPTF16axa

NASA Astrophysics Data System (ADS)

Hung, T.; Gezari, S.; Blagorodnova, N.; Roth, N.; Cenko, S. B.; Kulkarni, S. R.; Horesh, A.; Arcavi, I.; McCully, C.; Yan, Lin; Lunnan, R.; Fremling, C.; Cao, Y.; Nugent, P. E.; Wozniak, P.

2017-06-01

We report the discovery by the intermediate Palomar Transient Factory (iPTF) of a candidate tidal disruption event (TDE) iPTF16axa at z = 0.108 and present its broadband photometric and spectroscopic evolution from three months of follow-up observations with ground-based telescopes and Swift. The light curve is well fitted with a t -5/3 decay, and we constrain the rise time to peak to be <49 rest-frame days after disruption, which is roughly consistent with the fallback timescale expected for the ˜5 × 106 M ⊙ black hole inferred from the stellar velocity dispersion of the host galaxy. The UV and optical spectral energy distribution is well described by a constant blackbody temperature of T ˜ 3 × 104 K over the monitoring period, with an observed peak luminosity of 1.1 × 1044 erg s-1. The optical spectra are characterized by a strong blue continuum and broad He II and Hα lines, which are characteristic of TDEs. We compare the photometric and spectroscopic signatures of iPTF16axa with 11 TDE candidates in the literature with well-sampled optical light curves. Based on a single-temperature fit to the optical and near-UV photometry, most of these TDE candidates have peak luminosities confined between log(L [erg s-1]) = 43.4-44.4, with constant temperatures of a few ×104 K during their power-law declines, implying blackbody radii on the order of 10 times the tidal disruption radius, that decrease monotonically with time. For TDE candidates with hydrogen and helium emission, the high helium-to-hydrogen ratios suggest that the emission arises from high-density gas, where nebular arguments break down. We find no correlation between the peak luminosity and the black hole mass, contrary to the expectations for TDEs to have \\dot{M}\\propto {M}{BH}-1/2.

Transparent wood for functional and structural applications

NASA Astrophysics Data System (ADS)

Li, Yuanyuan; Fu, Qiliang; Yang, Xuan; Berglund, Lars

2017-12-01

Optically transparent wood combines mechanical performance with optical functionalities is an emerging candidate for applications in smart buildings and structural optics and photonics. The present review summarizes transparent wood preparation methods, optical and mechanical performance, and functionalization routes, and discusses potential applications. The various challenges are discussed for the purpose of improved performance, scaled-up production and realization of advanced applications. This article is part of a discussion meeting issue `New horizons for cellulose nanotechnology'.

On the optical search for Centaurus X-3.

NASA Technical Reports Server (NTRS)

Brucato, R. J.; Kristian, J.; Westphal, J. A.

1972-01-01

Elimination of the optical eclipsing binary LR Cen as a candidate for Cen X-3 on the basis of a real discrepancy of orbital periods. It is believed that the position coincidence of Wray 795 with Cen X-3 is not statistically significant.

The structure of Al-23 and astrophysical consequences

NASA Astrophysics Data System (ADS)

Zhai, Yongjun

Motivated by existing nuclear astrophysics problems, the b-decay of the proton rich nucleus 23 Al was studied for the first time with pure samples which were obtained by using the 1 H( 24 Mg, 23 Al)2n reaction and the MARS recoil separator at Texas A&M University. b and b-g coincidence measurements were made with a fast tape-transport system, scintillator, BGO and HPGe g detectors. The experiment allowed us to measure absolute b branching ratios and to determine log ft values for transitions to final states in 23 Mg, including the isobaric analog state (IAS), and, therefore, to determine unambiguously the spin and parity of the 23 Al ground state to be J p = 5/2 + . This work excludes the large increases in the radiative proton capture cross section for the reaction 22 Mg(p,g) 23 Al at astrophysical energies, which were implied by claims that the spin and parity of the 23 Al ground state were J p = 1/2 + . More precise half life and mass determinations of 23 Al were obtained from the experimental data. The log ft for the Fermi transition to its isobaric analog state in 23 Mg was also determined for the first time. This IAS and a state 16 keV below it were observed, well separated in the same experiment for the first time. The b- decay scheme of the proton rich nucleus 23 Al was established. We can now solve a number of inconsistencies in the literature, exclude strong isospin mixing claimed before, and obtain a new determination of the resonance strength. The IAS and the state 16 keV below it are resonances in the 22 Na(p,g) 23 Mg reaction at energies that are important in novae. This second state turns out to be the resonance that gives the most important contribution in the depletion of 22Na from novae. Both of the reactions of 22 Mg(p,g) 23 Al and 22 Na(p,g) 23 Mg have been suggested as possible candidates for diverting some of the flux in oxygen-neon novae explosions from the A=22 into the A=23 mass chain.

Polarimetry of optically selected BL Lacertae candidates from the SDSS

NASA Astrophysics Data System (ADS)

Heidt, J.; Nilsson, K.

2011-05-01

We present and discuss polarimetric observations of 182 targets drawn from an optically selected sample of 240 probable BL Lac candidates out of the SDSS compiled by Collinge et al. (2005, AJ, 129, 2542). In contrast to most other BL Lac candidate samples extracted from the SDSS, its radio- and/or X-ray properties have not been taken into account for its derivation. Thus, because its selection is based on optical properties alone, it may be less prone to selection effects inherent in other samples derived at different frequencies, so it offers a unique opportunity to extract the first unbiased BL Lac luminosity function that is suitably large in size. We found 124 out of 182 targets (68%) to be polarized, 95 of the polarized targets (77%) to be highly polarized (>4%). The low-frequency peaked BL Lac candidates in the sample are on average only slightly more polarized than the high-frequency peaked ones. Compared to earlier studies, we found a high duty cycle in high polarization (˜ 66+2-14% to be >4% polarized) in high-frequency peaked BL Lac candidates. This may come from our polarization analysis, which minimizes the contamination by host galaxy light. No evidence of radio-quiet BL Lac objects in the sample was found. Our observations show that the probable sample of BL Lac candidates of Collinge et al. (2005) indeed contains a large number of bona fide BL Lac objects. High S/N spectroscopy and deep X-ray observations are required to construct the first luminosity function of optically selected BL Lac objects and to test more stringently for any radio-quiet BL Lac objects in the sample. Based on observations collected with the NTT on La Silla (Chile) operated by the European Southern Observatory in the course of the observing proposal 082.B-0133.Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA), operated jointly by the Max-Planck-Institut für Astronomie and the Instituto de Astrofisica de Andalucia (CSIC).Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/529/A162

Atypical dust species in the ejecta of classical novae

NASA Astrophysics Data System (ADS)

Helton, L. A.; Evans, A.; Woodward, C. E.; Gehrz, R. D.

2011-03-01

A classical nova outburst arises from a thermonuclear runaway in the hydrogen-rich material accreted onto the surface of a white dwarf in a binary system. These explosions can produce copious amounts of heavy element enriched material that are ejected violently into the surrounding interstellar medium. In some novae, conditions in the ejecta are suitable for the formation of dust of various compositions, including silicates, amorphous carbon, silicon carbide, and hydrocarbons. Multiple dust grain types are sometimes produced in the same system. CO formation in novae may not reach saturation, thus invalidating the usual paradigm in which the C:O ratio determines the dust species. A few novae, such as V705 Cas and DZ Cru, have exhibited emission features near 6, 8, and 11 μmthat are similar to "Unidentified Infrared" (UIR) features, but with significant differences in position and band structure. Here, we present Spitzer IRS spectra of two recent dusty novae, V2361 Cyg and V2362 Cyg, that harbor similar peculiar emission structures superimposed on features arising from carbonaceous grains. In other astronomical objects, such as star forming regions and young stellar objects, emission peaks at 6.2, 7.7, and 11.3 μmhave been associated with polycyclic aromatic hydrocarbon (PAH) complexes. We suggest that hydrogenated amorphous carbon (HAC) may be the source of these features in novae based upon the spectral behavior of the emission features and the conditions under which the dust formed.

Confirming Planetary Mass Candidate Companions in Ophiuchus

NASA Astrophysics Data System (ADS)

Fontanive, Clemence

2016-10-01

We propose for follow-up observations to confirm common proper motion for two candidate planetary mass companions, identified as part of our GO 12944 (PI Allers) search for companions to the youngest ( 0.5 Myr) brown dwarfs in the nearby Ophiuchus star-forming region. If confirmed to be co-moving, these would be among the lowest mass planetary mass companions imaged to date, with estimated masses <5 Jupiter Masses and would be vital benchmark objects for evolutionary models at these young ages. With our multi-band optical and IR photometric approach based on the SpT-Q relation seen for Ophiuchus brown dwarfs (Allers in prep.), we have already estimated the spectral type of our candidate companions. This approach distinguishes substellar objects from background interlopers based on the strength of the 1.4 um water feature robustly observed in MLTY objects but not in reddened background stars - both our candidates show clear evidence of absorption at 1.4 um. If confirmed, these candidate companions would significantly increase the census of young planetary mass companions around extremely young brown dwarfs. These candidate companions are too faint to be observed with ground-based laser guide star adaptive optics (LGS AO) nor is the 1.4 um water feature observable from the ground for such faint objects due to telluric absorption, thus HST is the only telescope in the world suitable for these observations.

ASAS-SN Discovery of a Possible Galactic Nova ASASSN-18ix

NASA Astrophysics Data System (ADS)

Stanek, K. Z.; Kochanek, C. S.; Shields, J. V.; Thompson, T. A.; Chomiuk, L.; Strader, J.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Dong, Subo; Stritzinger, M.

2018-04-01

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from multiple ASAS-SN telescopes, we detect a new bright transient source, possibly a classical nova, but it might also be a young, large amplitude outburst of a cataclysmic variable Object RA (J2000) DEC (J2000) Gal l (deg) Gal b (deg) Disc.

0935+05 Supernova 1995D in NGC 2962

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

1995-02-01

Reiki Kushida of Yatsugatake South Base Observatory discovers 0935+05 Supernova 1995D in NGC 2962. Magnitude 14.0. Position RA 09h 40m 54.79s DEC +5° 08' 26.6" (2000). Nova AQL 95 confirmed spectroscopically "as a slow 'FE II'-class nova in its post-maximum phase of development. Requests continue to monitor 1436-63 Nova Cir 95.

Educational Technology Program for Nova Scotia: Initial Phase. A Report on the Federal-Provincial Study of Educational Technology in Nova Scotia.

ERIC Educational Resources Information Center

deVille, Barry, Ed.

This is a preliminary examination of the present status and future prospects of educational technology in Nova Scotian schools. It is aimed at developing a plan to enhance the quality of educational technology by concentrating on systems which will be conducive to realizing educational goals at a reasonable cost. An overview of the institutional…

The electrification of Nova Scotia, 1884--1973: Technological modernization as a response to regional disparity

NASA Astrophysics Data System (ADS)

King, Lionel Bradley

This dissertation investigates local attempts to use technology as a force for regional rehabilitation in the economically-depressed Maritime region of Canada. At the time of Confederation in 1867, the Maritime province of Nova Scotia was prosperous, progressive, and cultured. By the end of the 1910s, the province had entered a long period of economic and social decline. Recent historiography has shown that, far from passively accepting their fate, Nova Scotians and other Maritimers, actively resisted marginalization with political, cultural, or social action. The thesis expands upon that literature by exploring technology-based strategies of provincial rehabilitation using Thomas P. Hughes's systems perspective and David E. Nye's semiotic approach. In doing so, it applies methods from the social constructivist school of the history of technology to the larger concerns of Maritime Canadian historiography. In large part, the North American culture of technology determined the ways in which Nova Scotians applied technological solutions to provincial concerns. Technology has long been central to the Western idea of progress. As the "high technology" of the late nineteenth and early twentieth centuries, electricity reinforced that view: its ephemeral nature and silent efficiency led people to endow it with transformative, even mystical, powers. As a result, Nova Scotians, adopted a program of electrical modernization in the late 1910s as a remedy for regional disparity. The Nova Scotia government's first step was the creation of an Ontario-style hydroelectric commission designed to bring order to the province's fragmented and inefficient electrical network. Over the next few decades, the Nova Scotia Power Commission implemented rural electrification, home modernization, and regional system-building models that had already proven successful in Ontario and the United States. The system-building philosophies behind these programs were adapted to local conditions and disseminated throughout the province by politicians, engineers, businesspeople, and social reformers. Although electrical modernization failed to address the structural reasons for the province's decline, Nova Scotians continued to include it in their provincial rehabilitation plans until the 1960s. In sum, the electrification of Nova Scotia was not merely a technical event, but was shaped by the province's aspiration to regain its prior position in Confederation.

Precision mechanisms for optics in a vacuum cryogenic environment

NASA Astrophysics Data System (ADS)

Navarro, R.; Elswijk, E.; Tromp, N.; Kragt, J.; Kroes, G.; Hanenburg, H.; de Haan, M.; Schuil, M.; Teuwen, M.; Janssen, H.; Venema, L.

2017-11-01

To achieve superb stability in cryogenic optical systems, NOVA-ASTRON generally designs optical instruments on the basis of a 'no adjustments' philosophy. This means that in principle no corrections are possible after assembly. The alignment precision and consequently the performance of the instrument is guaranteed from the design, the tolerance analysis and the detailed knowledge of the material behavior and manufacturing process. This resulted in a higher degree of integrated optomechanical-cryogenic design with fewer parts, but with a higher part complexity. The 'no adjustments' strategy is successful because in the end the risk on instrument performance and project delays is much reduced. Astronomical instrument specifications have become more challenging over the years. Recent designs of the European Southern Observatory Very Large Telescope Interferometer (ESO VLTI) 4 Telescope combiner MATISSE include hundreds of optical components in a cryogenic environment. Despite the large number of optical components the alignment accuracy and stability requirements are in the order of nanometers. The 'no adjustments' philosophy would be too costly in this case, because all components would need to meet extremely tight manufacturing specifications. These specifications can be relaxed dramatically if cryogenic mechanisms are used for alignment. Several mechanisms have been developed: a tip-tilt mirror mechanism, an optical path distance mechanism, a slider mechanism, a bistable cryogenic shutter and a mirror mounting clip. Key aspects of these mechanisms are that the optical element and mechanism are combined in a compact single component, driven by e.g. self braking piezo actuators in order to hold position without power. The design, realization and test results of several mechanisms are presented in this paper.

The long-term optical evolution of the black hole candidate MAXI J1659-152

NASA Astrophysics Data System (ADS)

Corral-Santana, Jesús M.; Torres, Manuel A. P.; Shahbaz, Tariq; Bartlett, Elizabeth S.; Russell, David M.; Kong, Albert K. H.; Casares, Jorge; Muñoz-Darias, Teodoro; Bauer, Franz E.; Homan, Jeroen; Jonker, Peter G.; Mata Sánchez, Daniel; Wevers, Thomas; Rodríguez-Gil, Pablo; Lewis, Fraser; Schreuder, Laurien

2018-03-01

We present 5 yr of optical and infrared data of the black hole candidate MAXI J1659-152 covering its 2010 outburst, decay, and quiescence. Combining optical data taken during the outburst decay, we obtain an orbital period of 2.414 ± 0.005 h, in perfect agreement with the value previously measured from X-ray dips. In addition, we detect a clear H α excess in MAXI J1659-152 with data taken during the outburst decay. We also detect a single hump modulation most likely produced by irradiation. Assuming that the maximum occurs at orbital phase 0.5, we constrain the phase of the X-ray dips to be ˜0.65. We also detect the quiescent optical counterpart at r΄ = 24.20 ± 0.08, I = 23.32 ± 0.02, and H = 20.7 ± 0.1. These magnitudes provide colour indices implying an M2-M5 donor star assuming 60 per cent contribution from a disc component in the r΄ band.

High Resolution Active Optics Observations from the Kepler Follow-up Observation Program

NASA Astrophysics Data System (ADS)

Gautier, Thomas N.; Ciardi, D. R.; Marcy, G. W.; Hirsch, L.

2014-01-01

The ground based follow-up observation program for candidate exoplanets discovered with the Kepler observatory has supported a major effort for high resolution imaging of candidate host stars using adaptive optics wave-front correction (AO), speckle imaging and lucky imaging. These images allow examination of the sky as close as a few tenths of an arcsecond from the host stars to detect background objects that might be the source of the Kepler transit signal instead of the host star. This poster reports on the imaging done with AO cameras on the Keck, Palomar 5m and Shane 3m (Lick Observatory) which have been used to obtain high resolution images of over 500 Kepler Object of Interest (KOI) exoplanet candidate host stars. All observations were made at near infrared wavelengths in the J, H and K bands, mostly using the host target star as the AO guide star. Details of the sensitivity to background objects actually attained by these observations and the number of background objects discovered are presented. Implications to the false positive rate of the Kepler candidates are discussed.

DISCOVERING BRIGHT QUASARS AT INTERMEDIATE REDSHIFTS BASED ON OPTICAL/NEAR-INFRARED COLORS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Xue-Bing; Zuo, Wenwen; Yang, Jinyi

2013-10-01

The identification of quasars at intermediate redshifts (2.2 < z < 3.5) has been inefficient in most previous quasar surveys since the optical colors of quasars are similar to those of stars. The near-IR K-band excess technique has been suggested to overcome this difficulty. Our recent study also proposed to use optical/near-IR colors for selecting z < 4 quasars. To verify the effectiveness of this method, we selected a list of 105 unidentified bright targets with i ≤ 18.5 from the quasar candidates of SDSS DR6 with both SDSS ugriz optical and UKIDSS YJHK near-IR photometric data, which satisfy ourmore » proposed Y – K/g – z criterion and have photometric redshifts between 2.2 and 3.5 estimated from the nine-band SDSS-UKIDSS data. We observed 43 targets with the BFOSC instrument on the 2.16 m optical telescope at Xinglong station of the National Astronomical Observatory of China in the spring of 2012. We spectroscopically identified 36 targets as quasars with redshifts between 2.1 and 3.4. The high success rate of discovering these quasars in the SDSS spectroscopic surveyed area further demonstrates the robustness of both the Y – K/g – z selection criterion and the photometric redshift estimation technique. We also used the above criterion to investigate the possible stellar contamination rate among the quasar candidates of SDSS DR6, and found that the rate is much higher when selecting 3 < z < 3.5 quasar candidates than when selecting lower redshift candidates (z < 2.2). The significant improvement in the photometric redshift estimation when using the nine-band SDSS-UKIDSS data over the five-band SDSS data is demonstrated and a catalog of 7727 unidentified quasar candidates in SDSS DR6 selected with optical/near-IR colors and having photometric redshifts between 2.2 and 3.5 is provided. We also tested the Y – K/g – z selection criterion with the recently released SDSS-III/DR9 quasar catalog and found that 96.2% of 17,999 DR9 quasars with UKIDSS Y- and K-band data satisfy our criterion. With some available samples of red quasars and type II quasars, we find that 88% and 96.5% of these objects can be selected by the Y – K/g – z criterion, respectively, which supports our claim that using the Y – K/g – z criterion efficiently selects both unobscured and obscured quasars. We discuss the implications of our results on the ongoing and upcoming large optical and near-IR sky surveys.« less

Neutrino Physics in the NOvA Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez, Mayly

2016-09-19

The objective of the experimental neutrino physics program at ISU is to contribute to the NOvA experiment in order to enable the measurement of the unknown neutrino parameters: the CP violation phase and the mass hierarchy. In the Summer of 2015, the NOvA Collaboration released results from the first year of data collected by the experiment. The ISU group played an important role in various aspects of these results including authoring one of the two resulting publications. During this project period and with the support of this grant the PI and her group made leading contributions both in data analysismore » and operations to the NOvA experiment.« less

An X-ray survey of nine historical novae. [HEAO 2 observations

NASA Technical Reports Server (NTRS)

Becker, R. H.; Marshall, F. E.

1980-01-01

The Einstein Observatory imaging proportional counter was used to search for X-ray emission from nine nearby historical novae. Six of the novae were detected with estimated X-ray intensities between .1 to 4 keV of 10 to the -13th power to 10 to the -11th power ergs/sq cm-s, comparable to the intensities of previously detected cataclysmic variables. The X-ray intensity of one of the novae, V603 Aql, varies over times of several hundred seconds. The data suggest a correlation between the decay rate of the historical outburst and the current X-ray luminosity. Alternatively, the X-ray luminosity may be related to the inclination of the binary system.

The distances of the Galactic Novae

NASA Astrophysics Data System (ADS)

Ozdonmez, Aykut; Guver, Tolga; Cabrera-Lavers, Antonio; Ak, Tansel

2016-07-01

Using location of the RC stars on the CMDs obtained from the UKIDSS, VISTA and 2MASS photometry, we have derived the reddening-distance relations towards each Galactic nova for which at least one independent reddening measurement exists. We were able to determine the distances of 72 Galactic novae and set lower limits on the distances of 45 systems. The reddening curves of the systems are presented. These curves can be also used to estimate reddening or the distance of any source, whose location is close to the position of the nova in our sample. The distance measurement method in our study can be easily applicable to any source, especially for ones that concentrated along the Galactic plane.

Grazing Incidence Nickel Replicated Optics for Hard X-ray Telescopes

NASA Technical Reports Server (NTRS)

Peturzzo, J. J., III; Elsner, R. F.; Joy, M. K.; ODell, S. L.; Weisskopf, M. C.

1997-01-01

The requirements for future hard x-ray (up to 50 keV) telescopes are lightweight, high angular resolution optics with large collecting areas. Grazing incidence replicated optics are an excellent candidate for this, type of mission, providing better angular resolution, comparable area/unit mass, and simpler fabrication than multilayer-coated foils. Most importantly, the technology to fabricate the required optics currently exists. A comparison of several hard x-ray telescope designs will be presented.

Ticking Stellar Time Bomb Identified - Astronomers find prime suspect for a Type Ia supernova

NASA Astrophysics Data System (ADS)

2009-11-01

Using ESO's Very Large Telescope and its ability to obtain images as sharp as if taken from space, astronomers have made the first time-lapse movie of a rather unusual shell ejected by a "vampire star", which in November 2000 underwent an outburst after gulping down part of its companion's matter. This enabled astronomers to determine the distance and intrinsic brightness of the outbursting object. It appears that this double star system is a prime candidate to be one of the long-sought progenitors of the exploding stars known as Type Ia supernovae, critical for studies of dark energy. "One of the major problems in modern astrophysics is the fact that we still do not know exactly what kinds of stellar system explode as a Type Ia supernova," says Patrick Woudt, from the University of Cape Town and lead author of the paper reporting the results. "As these supernovae play a crucial role in showing that the Universe's expansion is currently accelerating, pushed by a mysterious dark energy, it is rather embarrassing." The astronomers studied the object known as V445 in the constellation of Puppis ("the Stern") in great detail. V445 Puppis is the first, and so far only, nova showing no evidence at all for hydrogen. It provides the first evidence for an outburst on the surface of a white dwarf [1] dominated by helium. "This is critical, as we know that Type Ia supernovae lack hydrogen," says co-author Danny Steeghs, from the University of Warwick, UK, "and the companion star in V445 Pup fits this nicely by also lacking hydrogen, instead dumping mainly helium gas onto the white dwarf." In November 2000, this system underwent a nova outburst, becoming 250 times brighter than before and ejecting a large quantity of matter into space. The team of astronomers used the NACO adaptive optics instrument [2] on ESO's Very Large Telescope (VLT) to obtain very sharp images of V445 Puppis over a time span of two years. The images show a bipolar shell, initially with a very narrow waist, with lobes on each side. Two knots are also seen at both the extreme ends of the shell, which appear to move at about 30 million kilometres per hour. The shell - unlike any previously observed for a nova - is itself moving at about 24 million kilometres per hour. A thick disc of dust, which must have been produced during the last outburst, obscures the two central stars. "The incredible detail that we can see on such small scales - about hundred milliarcseconds, which is the apparent size of a one euro coin seen from about forty kilometres - is only possible thanks to the adaptive optics technology available on large ground-based telescopes such as ESO's VLT," says Steeghs. A supernova is one way that a star can end its life, exploding in a display of grandiose fireworks. One family of supernovae, called Type Ia supernovae, are of particular interest in cosmology as they can be used as "standard candles" to measure distances in the Universe [3] and so can be used to calibrate the accelerating expansion that is driven by dark energy. One defining characteristic of Type Ia supernovae is the lack of hydrogen in their spectrum. Yet hydrogen is the most common chemical element in the Universe. Such supernovae most likely arise in systems composed of two stars, one of them being the end product of the life of sun-like stars, or white dwarfs. When such white dwarfs, acting as stellar vampires that suck matter from their companion, become heavier than a given limit, they become unstable and explode [4]. The build-up is not a simple process. As the white dwarf cannibalises its prey, matter accumulates on its surface. If this layer becomes too dense, it becomes unstable and erupts as a nova. These controlled, mini-explosions eject part of the accumulated matter back into space. The crucial question is thus to know whether the white dwarf can manage to gain weight despite the outburst, that is, if some of the matter taken from the companion stays on the white dwarf, so that it will eventually become heavy enough to explode as a supernova. Combining the NACO images with data obtained with several other telescopes [5] the astronomers could determine the distance of the system - about 25 000 light-years from the Sun - and its intrinsic brightness - over 10 000 times brighter than the Sun. This implies that the vampire white dwarf in this system has a high mass that is near its fatal limit and is still simultaneously being fed by its companion at a high rate. "Whether V445 Puppis will eventually explode as a supernova, or if the current nova outburst has pre-empted that pathway by ejecting too much matter back into space is still unclear," says Woudt. "But we have here a pretty good suspect for a future Type Ia supernova!" Notes [1] White dwarfs represent the evolutionary end product of stars with initial masses up to a few solar masses. A white dwarf is the burnt-out stellar core that is left behind when a star like the Sun sheds its outer layers towards the end of its active life. It is composed essentially of carbon and oxygen. This process normally also leads to the formation of a surrounding planetary nebula. [2] Adaptive optics is a technique that allows astronomers to obtain an image of an object free from the blurring effect of the atmosphere. See the adaptive optics page at ESO: http://www.eso.org/public/astronomy/technology/adaptive_optics.html [3] See for example http://www.eso.org/~bleibund/papers/EPN/epn.html [4] This Chandrasekhar limit, named after the Indian physicist Subrahmanyan Chandrasekhar, is nearly 1.4 times the mass of the Sun. When a white dwarf reaches a mass above this limit, either by sucking matter from a companion or merging with another white dwarf, it will turn itself into a thermonuclear bomb that will burn carbon and oxygen explosively. [5] The team also used the SOFI instrument on ESO's New Technology Telescope, the IMACS spectrograph on the 6.5-metre Magellan Baade telescope, and the Infrared Survey Facility and the SIRIUS camera at the Sutherland station of the South African Astronomical Observatory. More information This research was presented in a paper to appear in the 20 November 2009 issue of the Astrophysical Journal, vol. 706, p. 738 ("The expanding bipolar shell of the helium nova V445 Puppis", by P. A. Woudt et al.). The team is composed of P. A. Woudt and B. Warner (University of Cape Town, South Africa), D. Steeghs and T. R. Marsh (University of Warwick, UK), M. Karovska and G. H. A. Roelofs (Harvard-Smithsonian Center for Astrophysics, Cambridge MA, USA), P. J. Groot and G. Nelemans (Radboud University Nijmegen, the Netherlands), T. Nagayama (Kyoto University, Japan), D. P. Smits (University of South Africa, South Africa), and T. O'Brien (University of Manchester, UK). ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky".

Finding Hidden Quasars with UKIDSS and AAOmega

NASA Astrophysics Data System (ADS)

Maddox, Natasha; Hewett, P. C.; Warren, S. J.; Croom, S. M.

2007-05-01

The number of luminous quasars that have thus far eluded optical surveys is a subject of ongoing debate. Dust reddening and significant host galaxy light tend to exclude candidates from traditional UV-excess selection. UKIDSS, the near-infrared counterpart to SDSS, has started to provide the large area NIR data required to quantify the number of quasars missing from optical surveys. The quasar candidate list was chosen from the Early Data Release of the UKIDSS Large Area Survey (LAS), which aims to cover 2000 square degrees in two years. Requiring each object to have K<17, J<19.5 (the detection limit of the LAS) and a detection in SDSS were the only restrictions imposed on the candidates. A simple cut in gJK colour space, exploiting the K-band excess of quasars compared to stars, then separates the quasar candidates from the stellar locus. Optical-NIR colour selection with relaxed restrictions on morphology is less sensitive to dust reddening, so provides a more complete candidate list, suitable for follow-up observation with the new AAOmega spectrograph on the Anglo-Australian Telescope. With spectroscopic observations covering nearly 20 square degrees taken at the AAT, this is by far the largest K-band selected quasar sample to date. Many new quasars have been identified, in addition to known quasars being recovered. Several of the newly discovered quasars lie in regions of colour space typically excluded by UV selection. This study highlights the effectiveness of the K-excess technique in selecting quasars that do not necessarily exhibit the classic UV excess, either due to intrinsic SED shape or dust reddening. Combining upcoming UKIDSS data releases with scheduled AAT observations will increase the area surveyed by several times, thus moving closer to fully quantifying the number of luminous, reddened quasars.

Characterizing the WISE-selected heavily obscured quasar population with optical spectroscopy from the Southern African Large Telescope

NASA Astrophysics Data System (ADS)

Hviding, Raphael E.; Hickox, Ryan C.; Hainline, Kevin N.; Carroll, Christopher M.; DiPompeo, Michael A.; Yan, Wei; Jones, Mackenzie L.

2018-02-01

We present the results of an optical spectroscopic survey of 46 heavily obscured quasar candidates. Objects are selected using their mid-infrared (mid-IR) colours and magnitudes from the Wide-Field Infrared Survey Explorer (WISE) anzd their optical magnitudes from the Sloan Digital Sky Survey. Candidate Active Galactic Nuclei (AGNs) are selected to have mid-IR colours indicative of quasar activity and lie in a region of mid-IR colour space outside previously published X-ray based selection regions. We obtain optical spectra for our sample using the Robert Stobie Spectrograph on the Southern African Large Telescope. 30 objects (65 per cent) have identifiable emission lines, allowing for the determination of spectroscopic redshifts. Other than one object at z ˜ 2.6, candidates have moderate redshifts ranging from z = 0.1 to 0.8 with a median of 0.3. 21 (70 per cent) of our objects with identified redshift (46 per cent of the whole sample) are identified as AGNs through common optical diagnostics. We model the spectral energy distributions of our sample and found that all require a strong AGN component, with an average intrinsic AGN fraction at 8 μm of 0.91. Additionally, the fits require large extinction coefficients with an average E(B - V)AGN = 17.8 (average A(V)AGN = 53.4). By focusing on the area outside traditional mid-IR photometric cuts, we are able to capture and characterize a population of deeply buried quasars that were previously unattainable through X-ray surveys alone.

Slow magnetic monopoles search in NOvA

NASA Astrophysics Data System (ADS)

Antoshkin, Alexander; Frank, Martin

2018-04-01

The NOvA far detector is well suited for finding exotic particles due to its technical features (see [1]). One type of those exotic particles is a "slow" magnetic monopole. It is assumed that the energy deposition of such monopoles should be enough to be registered (see [2]). Measurement of the expected signals was performed on the NOvA test bench at JINR (see [3]). Result of this measurement allows us to perform slow monopole's research using NOvA software and hardware with high efficiency. As a whole, the research can lead to a discovery, or it can limit the existence of monopoles in a wide range of parameters, previously unreachable in other experiments (MACRO, SLIM, RICE, IceCube). Several special software tools have been developed. Slow Monopole Trigger has been created and implemented in the NOvA Data-Driven-Trigger system. Also, an online reconstruction algorithm has been developed and tested on 5% of the data. A technical description of these tools and current results of the analysis are presented in this work.

ORIGINS OF ABSORPTION SYSTEMS OF CLASSICAL NOVA V2659 CYG (NOVA CYG 2014)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arai, A.; Kawakita, H.; Shinnaka, Y.

2016-10-10

We report on high-dispersion spectroscopy results of a classical nova V2659 Cyg (Nova Cyg 2014) that are taken 33.05 days after the V -band maximum. The spectrum shows two distinct blueshifted absorption systems originating from H i, Fe ii, Ca ii, etc. The radial velocities of the absorption systems are −620 km s{sup −1}, and −1100 to −1500 km s{sup −1}. The higher velocity component corresponds to the P-Cygni absorption features frequently observed in low-resolution spectra. Much larger numbers of absorption lines are identified at the lower velocity. These mainly originate from neutral or singly ionized Fe-peak elements (Fe i,more » Ti ii, Cr ii, etc.). Based on the results of our spectroscopic observations, we discuss the structure of the ejecta of V2659 Cyg. We conclude that the low- and high-velocity components are likely to be produced by the outflow wind and the ballistic nova ejecta, respectively.« less

X-ray and Optical Observations of NGC 1788

NASA Astrophysics Data System (ADS)

Alcalá, J. M.; Covino, E.; Wachter, S.; Hoard, D. W.; Sterzik, M. F.; Durisen, R. H.; Freyberg, M.; Cooksey, K.

We report on the results of ROSAT High Resolution Imager (HRI) X-ray observations and optical wide-field spectroscopy and imaging in the star forming region NGC 1788. Several new low mass pre-main sequence (PMS) stars have been found based on intermediate resolution spectroscopy. Many new PMS candidate members of NGC 1788 are selected using the spectroscopically confirmed PMS stars to define the PMS locus in color-magnitude diagrams. Some objects with very red colors detected just above the limiting magnitude of our images, are good candidates for young Brown Dwarfs (BDs). The BD nature of these objects need to be confirmed with subsequent IR observations.

Lick Observatory Optical SETI: targeted search and new directions.

PubMed

Stone, R P S; Wright, S A; Drake, F; Muñoz, M; Treffers, R; Werthimer, D

2005-10-01

Lick Observatory's Optical SETI (search for extraterrestrial intelligence) program has been in regular operation for 4.5 years. We have observed 4,605 stars of spectral types F-M within 200 light-years of Earth. Occasionally, we have appended objects of special interest, such as stars with known planetary systems. We have observed 14 candidate signals ("triple coincidences"), all but one of which are explained by transient local difficulties. Additional observations of the remaining candidate have failed to confirm arriving pulse events. We now plan to proceed in a more economical manner by operating in an unattended drift scan mode. Between operational and equipment modifications, efficiency will more than double.

Active 2D materials for on-chip nanophotonics and quantum optics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiue, Ren-Jye; Efetov, Dmitri K.; Grosso, Gabriele

Abstract Two-dimensional materials have emerged as promising candidates to augment existing optical networks for metrology, sensing, and telecommunication, both in the classical and quantum mechanical regimes. Here, we review the development of several on-chip photonic components ranging from electro-optic modulators, photodetectors, bolometers, and light sources that are essential building blocks for a fully integrated nanophotonic and quantum photonic circuit.

Active 2D materials for on-chip nanophotonics and quantum optics

NASA Astrophysics Data System (ADS)

Shiue, Ren-Jye; Efetov, Dmitri K.; Grosso, Gabriele; Peng, Cheng; Fong, Kin Chung; Englund, Dirk

2017-03-01

Two-dimensional materials have emerged as promising candidates to augment existing optical networks for metrology, sensing, and telecommunication, both in the classical and quantum mechanical regimes. Here, we review the development of several on-chip photonic components ranging from electro-optic modulators, photodetectors, bolometers, and light sources that are essential building blocks for a fully integrated nanophotonic and quantum photonic circuit.

Field experience silvicultural cleaning project in young spruce and fir stands in central Nova Scotia

Treesearch

Theodore C. Tryon; Thomas W. Hartranft

1977-01-01

Silvicultural cleaning production varied from .15 to .34 acres per man day using light weight chain saws in young Spruce and Fir stands in Central Nova Scotia. Direct labor and saw costs, in cleaning young softwood stands in Nova Scotia, can be expected to range generally from $55.00 to $90.00 per acre, depending on crew experience, stand density, and equipment used....

Modeling SOFIA/FORCAST spectra of the classical nova V5568 Sgr with 3D pyCloudy

NASA Astrophysics Data System (ADS)

Calvén, Emilia; Helton, L. Andrew; Sankrit, Ravi

2017-06-01

We present our first results modelling Nova V5668 Sgr using the pseudo-3D photoionization code pyCloudy (Morisset 2013). V5668 Sgr is a classical nova of the FeII class (Williams et al. 2015; Seach 2015) showing signs of a bipolar flow (Banerjee et al. 2015). We construct a grid of models, which use hour-glass morphologies and a range of C, N, O and Ne abundances, to fit a suite of spectroscopic data in the near and mid-IR obtained between 82 to 556 days after outburst. The spectra were obtained using the FORCAST mid-IR instrument onboard the NASA Stratospheric Observatory for Infrared Astronomy (SOFIA) and the 1.2m near-IR telescope of the Mount Abu Infrared Observatory. Additional photometric data from FORCAST, The STONY BROOK/SMARTS Atlas of (mostly) Southern Novae (Walter et al., 2012) and the American Association of Variable Star Observers (AAVSO) were used to supplement the spectral data to obtain the SED of the nova at different times during its evolution. The work presented here is the initial step towards developing a large database of 1D and 3D models that may be used to derive the elemental abundances and dust properties of classical novae.

VizieR Online Data Catalog: New gamma-ray blazar candidates in the 3PBC (Maselli+, 2013)

NASA Astrophysics Data System (ADS)

Maselli, A.; Massaro, F.; Cusumano, G.; D'Abrusco, R.; La Parola, V.; Paggi, A.; Segreto, A.; Smith, H. A.; Tosti, G.

2013-06-01

We searched for γ-ray blazar candidates among the 382 unidentified hard X-ray sources of the third Palermo BAT Catalog (3PBC) obtained from the analysis of 66 months of Swift Burst Alert Telescope (BAT) survey data and listing 1586 sources. We adopted a recently developed association method based on the peculiar infrared colors that characterize the γ-ray blazars included in the second catalog of active galactic nuclei detected by the Fermi Large Area Telescope. We used this method exploiting the data of the all-sky survey performed by the Wide-field Infrared Survey Explorer (WISE) to establish correspondences between unidentified 3PBC sources and WISE γ-ray blazar candidates located within the BAT positional uncertainty region at a 99% confidence level. We obtained a preliminary list of candidates for which we analyzed all the available data in the Swift archive to complement the information in the literature and in the radio, infrared, and optical catalogs with the information on their optical-UV and soft X-ray emission. Requiring the presence of radio and soft X-ray counterparts consistent with the infrared positions of the selected WISE sources, as well as a blazar-like radio morphology, we finally obtained a list of 24 γ-ray blazar candidates. (2 data files).

Searching for New γ-Ray Blazar Candidates in the Third Palermo BAT Hard X-Ray Catalog with WISE

NASA Astrophysics Data System (ADS)

Maselli, A.; Massaro, F.; Cusumano, G.; D'Abrusco, R.; La Parola, V.; Paggi, A.; Segreto, A.; Smith, Howard A.; Tosti, G.

2013-06-01

We searched for γ-ray blazar candidates among the 382 unidentified hard X-ray sources of the third Palermo BAT Catalog (3PBC) obtained from the analysis of 66 months of Swift Burst Alert Telescope (BAT) survey data and listing 1586 sources. We adopted a recently developed association method based on the peculiar infrared colors that characterize the γ-ray blazars included in the second catalog of active galactic nuclei detected by the Fermi Large Area Telescope. We used this method exploiting the data of the all-sky survey performed by the Wide-field Infrared Survey Explorer (WISE) to establish correspondences between unidentified 3PBC sources and WISE γ-ray blazar candidates located within the BAT positional uncertainty region at a 99% confidence level. We obtained a preliminary list of candidates for which we analyzed all the available data in the Swift archive to complement the information in the literature and in the radio, infrared, and optical catalogs with the information on their optical-UV and soft X-ray emission. Requiring the presence of radio and soft X-ray counterparts consistent with the infrared positions of the selected WISE sources, as well as a blazar-like radio morphology, we finally obtained a list of 24 γ-ray blazar candidates.

iPTF search for an optical counterpart to gravitational-wave transient GW150914

DOE PAGES

Kasliwal, M. M.; Cenko, S. B.; Singer, L. P.; ...

2016-06-16

The intermediate Palomar Transient Factory (iPTF) autonomously responded to and promptly tiled the error region of the first gravitational-wave event GW150914 to search for an optical counterpart. Only a small fraction of the total localized region was immediately visible in the northern night sky, due both to Sun-angle and elevation constraints. Here, we report on the transient candidates identified and rapid follow-up undertaken to determine the nature of each candidate. Even in the small area imaged of 126 deg 2, after extensive filtering, eight candidates were deemed worthy of additional follow-up. Within two hours, all eight were spectroscopically classified bymore » the Keck II telescope. Curiously, even though such events are rare, one of our candidates was a superluminous supernova. We obtained radio data with the Jansky Very Large Array and X-ray follow-up with the Swift satellite for this transient. None of our candidates appear to be associated with the gravitational-wave trigger, which is unsurprising given that GW150914 came from the merger of two stellar-mass black holes. In conclusion, this end-to-end discovery and follow-up campaign bodes well for future searches in this post-detection era of gravitational waves.« less

Outburst of the recurrent nova V745 Sco

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2014-02-01

The outburst of the recurrent nova V745 Sco (Nova Sco 1937) by Rod Stubbings (Tetoora Road, VIC, Australia) at visual magnitude 9.0 on 2014 February 6.694 UT is reported. This recurrent nova is fading quickly. Follow-up observations of all types (visual, CCD, DSLR) are strongly encouraged, as is spectroscopy; fast time-series of this nova may be useful to detect possible flaring activity as was observed during the outburst of U Scorpii in 2010. Coincident time-series by multiple observers would be most useful for such a study, with a V-filter being preferred. Observations reported to the AAVSO International Database show V745 Sco at visual mag. 10.2 on 2014 Feb. 07.85833 UT (A. Pearce, Nedlands, W. Australia). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. Previous outbursts occurred in 1937 and 1989. The 1937 outburst was detected in 1958 (in decline at magnitude 11.0 on 1937 May 11.1 UT; outburst had occurred within the previous 19 days) by Lukas Plaut on plates taken by Hendrik van Gent at the Leiden Observatory; the object was announced as Nova Sco 1937 and later assigned the GCVS name V745 Sco. The 1989 outburst was detected on 1989 August 1.55 UT by Mati Morel (MMAT, Thornton, NSW, Australia) at visual magnitude 10.4 and in decline. Dr. Bradley Schaefer (Louisiana State University) reports (2010ApJS..187..275S) in his comprehensive analysis of the 10 known galactic recurrent novae (including V745 Sco) that the median interval between recurrent novae outbursts is 24 years. The interval since the 1989 outburst of V745 Sco is 24.10 years. See the Alert Notice for additional visual and multicolor photometry and for more details.

An Update on the Quirks of Pulsating, Accreting White Dwarfs

NASA Astrophysics Data System (ADS)

Szkody, Paula; Mukadam, Anjum S.; Gänsicke, Boris T.; Hermes, J. J.; Toloza, Odette

2015-06-01

At the 18th European White Dwarf Workshop, we reported results for several dwarf novae containing pulsating white dwarfs that had undergone an outburst in 2006-2007. HST and optical data on the white dwarfs in GW Lib, EQ Lyn and V455 And all showed different behaviors in the years following their outbursts. We continued to follow these objects for the last 2 years, providing timescales of 6-7 years past outburst. All three reached their optical quiescent values within 4 years but pulsational stability has not returned. EQ Lyn showed its pre-outburst pulsation period after 3 years, but it continues to show photometric variability that alternates between pulsation and disk superhump periods while remaining at quiescence. V455 And has almost reached its pre-outburst pulsation period, while GW Lib still remains heated and with a different pulsation spectrum than at quiescence. These results indicate that asteroseismology provides a unique picture of the effects of outburst heating on the white dwarf.

The Swift X-Ray Te1escope: Status and Performance

NASA Technical Reports Server (NTRS)

Burrows, David N.; Kennea, J.A.; Abbey, A.F.; Beardmore, A.; Campana, S.; Capalbi, M.; Chincarini, G.; Cusumano, G.; Evans, P.A.; Hill, J.E.;

SW Sextantis in an excited, low state

NASA Astrophysics Data System (ADS)

Groot, P. J.; Rutten, R. G. M.; van Paradijs, J.

2001-03-01

We present low-resolution spectrophotometric optical observations of the eclipsing nova-like cataclysmic variable SW Sex, the prototype of the SW Sex stars. We observed the system when it was in an unusual low state. The spectrum is characterized by the presence of strong Heii and Civ emission lines as well as the normal single peaked Balmer emission lines. The radial temperature profile of the disk follows the expected T~ R-3/4 only in the outer parts and flattens off inside 0.5 times the white dwarf Roche lobe radius. The single peaked emission lines originate in a region above the plane of the disk, at the position of the hot spot.

Sub-Nanosecond Cinematography In Laser Fusion Research: Current Techniques And Applications At The Lawrence Livermore National Laboratory*

NASA Astrophysics Data System (ADS)

Coleman, Lamar W...

1985-02-01

Progress in laser fusion research has increased the need for detail and precision in the diagnosis of experiments. This has spawned the development and use of sophisticated sub-nanosecond resolution diavostic systems. These systems typically use ultrafast x-ray or optical streak caAleras in combination. with spatially imaging or spectrally dispersing elements. These instruments provide high resolution data essential for understanding the processes occurrilltg in the interaction. of high. intensity laser light with targets. Several of these types of instruments and their capabilities will be discussed. The utilization of these kinds of diagnostics systems on the nearly completed 100 kJ Nova laser facility will be described.

Sub-nanosecond cinematography in laser fusion research: Current techniques and applications at the Lawrence Livermore Laboratory

NASA Astrophysics Data System (ADS)

Coleman, L. W.

1985-01-01

Progress in laser fusion research has increased the need for detail and precision in the diagnosis of experiments. This has spawned the development and use of sophisticated sub-nanosecond resolution diagnostic systems. These systems typically use ultrafast X-ray or optical streak cameras in combination with spatially imaging or spectrally dispersing elements. These instruments provide high resolution data essential for understanding the processes occurring in the interaction of high intensity laser light with targets. Several of these types of instruments and their capabilities will be discussed. The utilization of these kinds of diagnostics systems on the nearly completed 100 kJ Nova laser facility will be described.

Discovery of Possible Nova in M31 : P60-M31-080723

NASA Astrophysics Data System (ADS)

Kasliwal, M. M.; Cenko, S. B.; Rau, A.; Ofek, E. O.; Quimby, R.; Kulkarni, S. R.

2008-07-01

On UT 2008 July 23.33, P60-FasTING (Palomar 60-inch Fast Transients In Nearby Galaxies) discovered a faint optical transient in M31 at RA(J2000)=00:43:27.28, DEC(J2000) = +41:10:03.3. P60-M31-080723 has a brightness of g = 19.3 +/- 0.2 (photometric calibration wrt USNO-B) and it is offset by 8.1'E,6.1'S from the center of M31. It was also marginally detected on July 22.32 at g = 19.8 +/- 0.2. It was not detected on the previous several nights with 3-sigma upper limits in table below.

Peripheral elastic and inelastic scattering of O17,18 on light targets at 12 MeV/nucleon

NASA Astrophysics Data System (ADS)

Al-Abdullah, T.; Carstoiu, F.; Gagliardi, C. A.; Tabacaru, G.; Trache, L.; Tribble, R. E.

2014-06-01

A study of interaction of neutron-rich oxygen isotopes O17,18 with light targets has been undertaken in order to determine the optical potentials needed for the transfer reaction C13(O17,O18)C12. Optical potentials in both incoming and outgoing channels have been determined in a single experiment. This transfer reaction was used to infer the direct capture rate to the F17(p,γ)Ne18 which is essential to estimate the production of F18 at stellar energies in ONe novae. The success of the asymptotic normalization coefficient (ANC) as indirect method for astrophysics is guaranteed if the reaction mechanism is peripheral and the distorted wave Born approximation cross-section calculations are warranted and stable against the optical model potential (OMP) used. We demonstrate the stability of the ANC method and the OMP results by using good-quality elastic and inelastic-scattering data with stable beams before extending the procedures to rare-ion beams. The peripherality of our reaction is inferred from a semiclassical decomposition of the total-scattering amplitude into barrier and internal barrier components. Comparison between elastic scattering of O17, O18, and O16 projectiles is made.

Optical calibration of SNO +

NASA Astrophysics Data System (ADS)

Leming, Edward; SNO+ Collaboration

2015-04-01

Situated 2 km underground in Sudbury, Northern Ontario, the SNO + detector consists of an acrylic sphere 12 m in diameter containing 780 tons of target mass, surrounded by approximately 9,500 PMTs. For SNO, this target mass was heavy water, however the change to SNO + is defined by the change of this target mass to a novel scintillator. With the lower energy threshold, low intrinsic radioactivity levels and the best shielding against muons and cosmogenic activation of all existing neutrino experiments, SNO + will be sensitive to exciting new physics. The experiment will be studying solar, reactor, super nova and geo-neutrinos, though the main purpose of SNO + is the search for neutrinoless double-beta decay of Te-130. To meet the requirements imposed by the physics on detector performance, a detailed optical calibration is needed. Source deployment must be kept to a minimum and eliminated if possible, in order to meet the stringent radiopurity requirements. This led to the development of the Embedded LED/laser Light Injection Entity (ELLIE) system. This talk provides a summary of the upgrades to from SNO to SNO +, discussing the requirements on and methods of optical calibration, focusing on the deployed laserball and ELLIE system.

Radio Observations as a Tool to Investigate Shocks and Asymmetries in Accreting White Dwarf Binaries

NASA Astrophysics Data System (ADS)

Weston, Jennifer H. S.

2016-07-01

This dissertation uses radio observations with the Karl G. Jansky Very Large Array (VLA) to investigate the mechanisms that power and shape accreting white dwarfs (WD) and their ejecta. We test the predictions of both simple spherical and steady-state radio emission models by examining nova V1723 Aql, nova V5589 Sgr, symbiotic CH Cyg, and two small surveys of symbiotic binaries. First, we highlight classical nova V1723 Aql with three years of radio observations alongside optical and X-ray observations. We use these observations to show that multiple outflows from the system collided to create early non-thermal shocks with a brightness temperature of ≥106 K. While the late-time radio light curve is roughly consistent an expanding thermal shell of mass 2x10-4 M⊙ solar masses, resolved images of V1723 Aql show elongated material that apparently rotates its major axis over the course of 15 months, much like what is seen in gamma-ray producing nova V959 Mon, suggesting similar structures in the two systems. Next, we examine nova V5589 Sgr, where we find that the early radio emission is dominated by a shock-powered non-thermal flare that produces strong (kTx > 33 keV) X-rays. We additionally find roughly 10-5 M⊙ solar masses of thermal bremsstrahlung emitting material, all at a distance of ~4 kpc. The similarities in the evolution of both V1723 Aql and V5589 Sgr to that of nova V959 Mon suggest that these systems may all have dense equatorial tori shaping faster flows at their poles. Turning our focus to symbiotic binaries, we first use our radio observations of CH Cyg to link the ejection of a collimated jet to a change of state in the accretion disk. We additionally estimate the amount of mass ejected during this period (10-7 M⊙ masses), and improve measurements of the period of jet precession (P=12013 ± 74 days). We then use our survey of eleven accretion-driven symbiotic systems to determine that the radio brightness of a symbiotic system could potentially be used as an indicator of w hether a symbiotic is powered predominantly by shell burning on the surface of the WD or by accretion. We additionally make the first ever radio detections of seven of the targets in our survey. Our survey of seventeen radio bright symbiotics, comparing observations before and after the upgrades to the VLA, shows the technological feasibility to resolve the nebulae of nearby symbiotic binaries, opening the door for new lines of research. We spatially resolve extended structure in several symbiotic systems in radio for the first time. Additionally, our observations reveal extreme radio variability in symbiotic BF Cyg before and after the production of a jet from the system. Our results from our surveys of symbiotics provide some support for the model of radio emission where the red giant wind is photoionized by the WD, and suggests that there may be a greater population of radio faint, accretion driven symbiotic systems. This work emphasizes the powerful nature of radio observations as a tool for understanding eruptive WD binaries and their outflows.

SEARCHES FOR MILLISECOND PULSAR CANDIDATES AMONG THE UNIDENTIFIED FERMI OBJECTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hui, C. Y.; Park, S. M.; Hu, C. P.

2015-08-10

Here we report the results of searching millisecond pulsar (MSP) candidates from the Fermi LAT second source catalog (2FGL). Seven unassociated γ-ray sources in this catalog are identified as promising MSP candidates based on their γ-ray properties. Through the X-ray analysis, we have detected possible X-ray counterparts, localized to an arcsecond accuracy. We have systematically estimated their X-ray fluxes and compared them with the corresponding γ-ray fluxes. The X-ray to γ-ray flux ratios for 2FGL J1653.6-0159 and 2FGL J1946.4-5402 are comparable with the typical value for pulsars. For 2FGL J1625.2-0020, 2FGL J1653.6-0159, and 2FGL J1946.4-5402, their candidate X-ray counterparts aremore » bright enough to perform a detailed spectral and temporal analysis to discriminate their thermal/non-thermal nature and search for the periodic signal. We have also searched for possible optical/IR counterparts at the X-ray positions. For the optical/IR source coincident with the brightest X-ray object associated with 2FGL J1120.0-2204, its spectral energy distribution is comparable with a late-type star. Evidence for the variability has also been found by examining its optical light curve. All the aforementioned 2FGL sources resemble a pulsar in one or more aspects, making them promising targets for follow-up investigations.« less

Infrared Dyes For Optical Storage

NASA Astrophysics Data System (ADS)

Jipson, V. B.; Jones, C. R.

1981-06-01

There is current interest in developing optical storage materials that can be written with GaAlAs lasers. Dyes which absorb strongly at those wavelengths are potential candidates for this application due to their attractive thermal properties. Through optical and thermal modelling, the properties that are necessary if they are to be writeable at energies of <=1 nJ are examined. A specific class of infrared absorbing dyes, squarylium, is discussed and preliminary data on optical characteristics, writing energy, and stability are presented.