Speeds of coronal mass ejections: SMM observations from 1980 and 1984-1989

NASA Technical Reports Server (NTRS)

Hundhausen, A. J.; Burkepile, J. T.; St. Cyr, O. C.

1994-01-01

The speeds of 936 features in 673 coronal mass ejections have been determined from trajectories observed with the Solar Maximum Mission (SMM) coronagraph in 1980 and 1984 to 1989. The distribution of observed speeds has a range (from 5th to 95th percentile) of 35 to 911 km/s; the average and median speeds are 349 and 285 km/s. The speed distributions of some selected classes of mass ejections are significantly different. For example, the speeds of 331 'outer loops' range from 80 to 1042 km/s; the average and median speeds for this class of ejections are 445 and 372 km/s. The speed distributions from each year of SMM observations show significant changes, with the annual average speeds varying from 157 (1984) to 458 km/s (1985). These variations are not simply related to the solar activity cycle; the annual averages from years near the sunspot maxima and minimum are not significantly different. The widths, latitudes, and speeds of mass ejections determined from the SMM observations are only weakly correlated. In particular, mass ejection speeds vary only slightly with the heliographic latitudes of the ejection. High-latitude ejections, which occur well poleward of the active latitudes, have speeds similar to active latitude ejections.

Mass ejection in failed supernovae: variation with stellar progenitor

NASA Astrophysics Data System (ADS)

Fernández, Rodrigo; Quataert, Eliot; Kashiyama, Kazumi; Coughlin, Eric R.

2018-05-01

We study the ejection of mass during stellar core-collapse when the stalled shock does not revive and a black hole forms. Neutrino emission during the protoneutron star phase causes a decrease in the gravitational mass of the core, resulting in an outward going sound pulse that steepens into a shock as it travels out through the star. We explore the properties of this mass ejection mechanism over a range of stellar progenitors using spherically symmetric, time-dependent hydrodynamic simulations that treat neutrino mass-loss parametrically and follow the shock propagation over the entire star. We find that all types of stellar progenitor can eject mass through this mechanism. The ejected mass is a decreasing function of the surface gravity of the star, ranging from several M⊙ for red supergiants to ˜0.1 M⊙ for blue supergiants and ˜10-3 M⊙ for Wolf-Rayet stars. We find that the final shock energy at the surface is a decreasing function of the core-compactness, and is ≲ 1047-1048 erg in all cases. In progenitors with a sufficiently large envelope, high core-compactness, or a combination of both, the sound pulse fails to unbind mass. Successful mass ejection is accompanied by significant fallback accretion that can last from hours to years. We predict the properties of shock breakout and thermal plateau emission produced by the ejection of the outer envelope of blue supergiant and Wolf-Rayet progenitors in otherwise failed supernovae.

Activity associated with coronal mass ejections at solar minimum - SMM observations from 1984-1986

NASA Technical Reports Server (NTRS)

St. Cyr, O. C.; Webb, D. F.

1991-01-01

Seventy-three coronal mass ejections (CMEs) observed by the coronagraph aboard SMM between 1984 and 1986 were examined in order to determine the distribution of various forms of solar activity that were spatially and temporally associated with mass ejections during solar minimum phase. For each coronal mass ejection a speed was measured, and the departure time of the transient from the lower corona estimated. Other forms of solar activity that appeared within 45 deg longitude and 30 deg latitude of the mass ejection and within +/-90 min of its extrapolated departure time were explored. The statistical results of the analysis of these 73 CMEs are presented, and it is found that slightly less than half of them were infrequently associated with other forms of solar activity. It is suggested that the distribution of the various forms of activity related to CMEs does not change at different phases of the solar cycle. For those CMEs with associations, it is found that eruptive prominences and soft X-rays were the most likely forms of activity to accompany the appearance of mass ejections.

3DCORE: Forward modeling of solar storm magnetic flux ropes for space weather prediction

NASA Astrophysics Data System (ADS)

Möstl, C.; Amerstorfer, T.; Palmerio, E.; Isavnin, A.; Farrugia, C. J.; Lowder, C.; Winslow, R. M.; Donnerer, J. M.; Kilpua, E. K. J.; Boakes, P. D.

2018-05-01

3DCORE forward models solar storm magnetic flux ropes called 3-Dimensional Coronal Rope Ejection (3DCORE). The code is able to produce synthetic in situ observations of the magnetic cores of solar coronal mass ejections sweeping over planets and spacecraft. Near Earth, these data are taken currently by the Wind, ACE and DSCOVR spacecraft. Other suitable spacecraft making these kind of observations carrying magnetometers in the solar wind were MESSENGER, Venus Express, MAVEN, and even Helios.

Determination of left ventricular volume, ejection fraction, and myocardial mass by real-time three-dimensional echocardiography

NASA Technical Reports Server (NTRS)

Qin, J. X.; Shiota, T.; Thomas, J. D.

2000-01-01

Reconstructed three-dimensional (3-D) echocardiography is an accurate and reproducible method of assessing left ventricular (LV) functions. However, it has limitations for clinical study due to the requirement of complex computer and echocardiographic analysis systems, electrocardiographic/respiratory gating, and prolonged imaging times. Real-time 3-D echocardiography has a major advantage of conveniently visualizing the entire cardiac anatomy in three dimensions and of potentially accurately quantifying LV volumes, ejection fractions, and myocardial mass in patients even in the presence of an LV aneurysm. Although the image quality of the current real-time 3-D echocardiographic methods is not optimal, its widespread clinical application is possible because of the convenient and fast image acquisition. We review real-time 3-D echocardiographic image acquisition and quantitative analysis for the evaluation of LV function and LV mass.

Determination of left ventricular volume, ejection fraction, and myocardial mass by real-time three-dimensional echocardiography.

PubMed

Qin, J X; Shiota, T; Thomas, J D

2000-11-01

Reconstructed three-dimensional (3-D) echocardiography is an accurate and reproducible method of assessing left ventricular (LV) functions. However, it has limitations for clinical study due to the requirement of complex computer and echocardiographic analysis systems, electrocardiographic/respiratory gating, and prolonged imaging times. Real-time 3-D echocardiography has a major advantage of conveniently visualizing the entire cardiac anatomy in three dimensions and of potentially accurately quantifying LV volumes, ejection fractions, and myocardial mass in patients even in the presence of an LV aneurysm. Although the image quality of the current real-time 3-D echocardiographic methods is not optimal, its widespread clinical application is possible because of the convenient and fast image acquisition. We review real-time 3-D echocardiographic image acquisition and quantitative analysis for the evaluation of LV function and LV mass.

Evidence that magnetic energy shedding in solar filament eruptions is the drive in accompanying flares and coronal mass ejections

NASA Technical Reports Server (NTRS)

Moore, Ronald L.

1988-01-01

The dependence of the magnetic energy on the field expansion and untwisting of the flux tube in which an erupting solar filament is embedded has been determined in order to evaluate the energy decrease in the erupting flux tube. Magnetic energy shedding by the filament-field eruption is found to be the driving mechanism in both filament-eruption flares and coronal mass ejections. Confined filament-eruption flares, filament-eruption flares with sprays and coronal mass ejections, and coronal mass ejections from quiescent filament eruptions are all shown to be similar types of events.

Jet behaviors and ejection mode recognition of electrohydrodynamic direct-write

NASA Astrophysics Data System (ADS)

Zheng, Jianyi; Zhang, Kai; Jiang, Jiaxin; Wang, Xiang; Li, Wenwang; Liu, Yifang; Liu, Juan; Zheng, Gaofeng

2018-01-01

By introducing image recognition and micro-current testing, jet behavior research was conducted, in which the real-time recognition of ejection mode was realized. To study the factors influencing ejection modes and the current variation trends under different modes, an Electrohydrodynamic Direct-Write (EDW) system with functions of current detection and ejection mode recognition was firstly built. Then a program was developed to recognize the jet modes. As the voltage applied to the metal tip increased, four jet ejection modes in EDW occurred: droplet ejection mode, Taylor cone ejection mode, retractive ejection mode and forked ejection mode. In this work, the corresponding relationship between the ejection modes and the effect on fiber deposition as well as current was studied. The real-time identification of ejection mode and detection of electrospinning current was realized. The results in this paper are contributed to enhancing the ejection stability, providing a good technical basis to produce continuous uniform nanofibers controllably.

Some crucial corona and prominence observations

NASA Technical Reports Server (NTRS)

Tandberg-Hanssen, E. A.

1986-01-01

A number of theories and hypotheses are currently being developed to explain the often complex behavior of corona and prominence plasmas. In order to test the theories and hypotheses certain crucial observations are necessary. Some of these observations are examined and a few conclusions are drawn. Corona mass balance, corona and prominence classifications, prominence formation and stability, and coronal mass ejection are dicussed.

Stimulated Motion Suppression (STMS): a New Approach to Break the Resolution Barrier for Ion Trap Mass Spectrometry

NASA Astrophysics Data System (ADS)

Zhou, Xiaoyu; Liu, Xinwei; Chiang, Spencer; Cao, Wenbo; Li, Ming; Ouyang, Zheng

2018-05-01

Ion trap is an excellent platform to perform tandem mass spectrometry (MS/MS), but has an intrinsic drawback in resolving power. Using ion resonant ejection as an example, the resolution degradation can be largely attributed to the broadening of the resonant frequency band (RFB) between ion motion and driving alternative-current (AC). To solve this problem, stimulated motion suppression (STMS) was developed. The key idea of STMS is the use of two suppression alternative-current (SAC) signals, which both have reversed initial phases to the main AC. The SACs can block the unexpected sideband ion resonances (or ejections), therefore playing a key role in sharpening the RFB. The proof-of-concept has been demonstrated through ion trajectory simulations and validated experimentally. STMS provides a new and versatile means for the improvement of the ion trap resolution, which for a long time has reached the bottleneck through conventional methods, e.g., increasing the radio-frequency (RF) voltage and decreasing the mass scan rate. At the end, it is worth noting that the idea of STMS is very general and principally can be applied in any RF device for the purposes of high-resolution mass analysis and ion isolation.

Spin stability of sounding rocket secondary payloads following high velocity ejections

NASA Astrophysics Data System (ADS)

Nelson, Weston M.

The Auroral Spatial Structures Probe (ASSP) mission is a sounding rocket mission studying solar energy input to space weather. ASSP requires the high velocity ejection (up to 50 m/s) of 6 secondary payloads, spin stabilized perpendicular to the ejection velocity. The proposed scientific instrumentation depends on a high degree of spin stability, requiring a maximum coning angle of less than 5°. It also requires that the spin axis be aligned within 25° of the local magnetic field lines. The maximum velocities of current ejection methods are typically less than 10m/s, and often produce coning angles in excess of 20°. Because of this they do not meet the ASSP mission requirements. To meet these requirements a new ejection method is being developed by NASA Wallops Flight Facility. Success of the technique in meeting coning angle and B-field alignment requirements is evaluated herein by modeling secondary payload dynamic behavior using a 6-DOF dynamic simulation employing state space integration written in MATLAB. Simulation results showed that secondary payload mass balancing is the most important factor in meeting stability requirements. Secondary mass payload properties will be measured using an inverted torsion pendulum. If moment of inertia measurement errors can be reduced to 0.5%, it is possible to achieve mean coning and B-field alignment angles of 2.16° and 2.71°, respectively.

Cardiac structure and function in Cushing's syndrome: a cardiac magnetic resonance imaging study.

PubMed

Kamenický, Peter; Redheuil, Alban; Roux, Charles; Salenave, Sylvie; Kachenoura, Nadjia; Raissouni, Zainab; Macron, Laurent; Guignat, Laurence; Jublanc, Christel; Azarine, Arshid; Brailly, Sylvie; Young, Jacques; Mousseaux, Elie; Chanson, Philippe

2014-11-01

Patients with Cushing's syndrome have left ventricular (LV) hypertrophy and dysfunction on echocardiography, but echo-based measurements may have limited accuracy in obese patients. No data are available on right ventricular (RV) and left atrial (LA) size and function in these patients. The objective of the study was to evaluate LV, RV, and LA structure and function in patients with Cushing's syndrome by means of cardiac magnetic resonance, currently the reference modality in assessment of cardiac geometry and function. Eighteen patients with active Cushing's syndrome and 18 volunteers matched for age, sex, and body mass index were studied by cardiac magnetic resonance. The imaging was repeated in the patients 6 months (range 2-12 mo) after the treatment of hypercortisolism. Compared with controls, patients with Cushing's syndrome had lower LV, RV, and LA ejection fractions (P < .001 for all) and increased end-diastolic LV segmental thickness (P < .001). Treatment of hypercortisolism was associated with an improvement in ventricular and atrial systolic performance, as reflected by a 15% increase in the LV ejection fraction (P = .029), a 45% increase in the LA ejection fraction (P < .001), and an 11% increase in the RV ejection fraction (P = NS). After treatment, the LV mass index and end-diastolic LV mass to volume ratio decreased by 17% (P < .001) and 10% (P = .002), respectively. None of the patients had late gadolinium myocardial enhancement. Cushing's syndrome is associated with subclinical biventricular and LA systolic dysfunctions that are reversible after treatment. Despite skeletal muscle atrophy, Cushing's syndrome patients have an increased LV mass, reversible upon correction of hypercortisolism.

The neutral current sheet and its radiation pairs of side sources in coronal mass ejections

NASA Astrophysics Data System (ADS)

Ji, Shu-Chen

Using the data observed with the soft X-ray telescope, hard X-ray telescope aboard on Yohkoh and the Nobeyama Radioheliograph on 1998 April 23, a comprehensive study on soft X-ray coronal mass ejection (SXRCME) and radio Type IV burst is carried out and some significant results are obtained as follows: A magnetic capacity belt (MCB) between two magnetic dipole sources (MDSs) was found and there were only a few activitation sources (ASs). During the MCB changed into a magnetic energy belt (MEB) by the ASs, activating energy and shining material both concentrated to the neutral current sheet (NCS) in the course of its formation. When two MDSs were put through by the MEB, the NCS formed and the SXRCME occurred. The matter ejected not only from the NCS, but also from the whole MEB. The expanding loop of the SXRCME had two foot points, both were just two MDSs. The head of the expanding loop always tended to the foot point of the weak source, because it was equilibrium point of magnetic pressures coming from two foot points. For this reason, its locus was neutral line. From this, the neutral line can also determine the position of NCS. Finally, the radiation pairs of side sources of NCS on the MEB are found.

Experimental observations on the links between surface perturbation parameters and shock-induced mass ejection

NASA Astrophysics Data System (ADS)

Monfared, S. K.; Oró, D. M.; Grover, M.; Hammerberg, J. E.; LaLone, B. M.; Pack, C. L.; Schauer, M. M.; Stevens, G. D.; Stone, J. B.; Turley, W. D.; Buttler, W. T.

2014-08-01

We have assembled together our ejecta measurements from explosively shocked tin acquired over a period of about ten years. The tin was cast at 0.99995 purity, and all of the tin targets or samples were shocked to loading pressures of about 27 GPa, allowing meaningful comparisons. The collected data are markedly consistent, and because the total ejected mass scales linearly with the perturbations amplitudes they can be used to estimate how much total Sn mass will be ejected from explosively shocked Sn, at similar loading pressures, based on the surface perturbation parameters of wavelength and amplitude. Most of the data were collected from periodic isosceles shapes that approximate sinusoidal perturbations. Importantly, however, we find that not all periodic perturbations behave similarly. For example, we observed that sawtooth (right triangular) perturbations eject more mass than an isosceles perturbation of similar depth and wavelength, demonstrating that masses ejected from irregular shaped perturbations cannot be normalized to the cross-sectional areas of the perturbations.

Reconstructing the Morphology of an Evolving Coronal Mass Ejection

DTIC Science & Technology

2009-01-01

694, 707 Wood, B. E., Howard, R. A ., Thernisien, A ., Plunkett, S. P., & Socker, D. G. 2009b, Sol. Phys., 259, 163 Wood, B. E., Karovska , M., Chen, J...Reconstructing the Morphology of an Evolving Coronal Mass Ejection B. E. Wood, R. A . Howard, D. G. Socker Naval Research Laboratory, Space Science...mission, we empirically reconstruct the time-dependent three-dimensional morphology of a coronal mass ejection (CME) from 2008 June 1, which exhibits

Mass-Loss Evolution in the EUV Low Corona from SDO/AIA Data

NASA Astrophysics Data System (ADS)

López, Fernando M.; Hebe Cremades, M.; Nuevo, Federico A.; Balmaceda, Laura A.; Vásquez, Alberto M.

2017-01-01

We carry out an analysis of the mass that is ejected from three coronal dimming regions observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. The three events are unambiguously identified with white-light coronal mass ejections (CMEs) that are associated in turn with surface activity of diverse nature: an impulsive (M-class) flare, a weak (B-class) flare, and a filament eruption without a flare. The use of three AIA coronal passbands allows applying a differential emission measure technique to define the dimming regions and identify their ejected mass through the analysis of the electronic density depletion associated with the eruptions. The temporal evolution of the mass loss from the three dimmings can be approximated by an exponential equation followed by a linear fit. We determine the mass of the associated CMEs from COR2 data. The results show that the ejected masses from the low corona represent a considerable amount of the CME mass. We also find that plasma is still being ejected from the low corona at the time when the CMEs reach the COR2 field of view. The temporal evolution of the angular width of the CMEs, of the dimming regions in the low corona, and of the flux registered by GOES in soft X-rays are all in close relation with the behavior of mass ejection from the low corona. We discuss the implications of our findings toward a better understanding of the temporal evolution of several parameters associated with the analyzed dimmings and CMEs.

Response of Jupiter's Aurora to Plasma Mass Loading Rate Monitored by the Hisaki Satellite During Volcanic Eruptions at Io

NASA Astrophysics Data System (ADS)

Kimura, T.; Hiraki, Y.; Tao, C.; Tsuchiya, F.; Delamere, P. A.; Yoshioka, K.; Murakami, G.; Yamazaki, A.; Kita, H.; Badman, S. V.; Fukazawa, K.; Yoshikawa, I.; Fujimoto, M.

2018-03-01

The production and transport of plasma mass are essential processes in the dynamics of planetary magnetospheres. At Jupiter, it is hypothesized that Io's volcanic plasma carried out of the plasma torus is transported radially outward in the rotating magnetosphere and is recurrently ejected as plasmoid via tail reconnection. The plasmoid ejection is likely associated with particle energization, radial plasma flow, and transient auroral emissions. However, it has not been demonstrated that plasmoid ejection is sensitive to mass loading because of the lack of simultaneous observations of both processes. We report the response of plasmoid ejection to mass loading during large volcanic eruptions at Io in 2015. Response of the transient aurora to the mass loading rate was investigated based on a combination of Hisaki satellite monitoring and a newly developed analytic model. We found that the transient aurora frequently recurred at a 2-6 day period in response to a mass loading increase from 0.3 to 0.5 t/s. In general, the recurrence of the transient aurora was not significantly correlated with the solar wind, although there was an exceptional event with a maximum emission power of 10 TW after the solar wind shock arrival. The recurrence of plasmoid ejection requires the precondition that an amount comparable to the total mass of magnetosphere, 1.5 Mt, is accumulated in the magnetosphere. A plasmoid mass of more than 0.1 Mt is necessary in case that the plasmoid ejection is the only process for mass release.

The velocity field of a coronal mass ejection - The event of September 1, 1980

NASA Technical Reports Server (NTRS)

Low, B. C.; Hundhausen, A. J.

1987-01-01

The velocity field of a mass ejection that was observed by the coronagraph of the SMM satellite over the northwest limb of the sun at about 0600 UT on September 1, 1980 is studied in detail. A descriptive account of the event is given, concentrating on qualitative features of the mass motion and suggesting a possible origin of the unusual two-loop structure. The velocity field is analyzed quantitatively, and the implications of the results for the mass ejection theory are considered. It is concluded that a self-similar description of the velocity field is a gross oversimplification and that although some evidence of wave propagation can be found, the bright features in the mass ejection are plasma structures moving with frozen-in magnetic fields, rather than waves propagating through plasmas and magnetic fields.

IR Variability During a Shell Ejection of Eta Carinae

NASA Astrophysics Data System (ADS)

Smith, Nathan

2006-02-01

Every 5.5 years, η Carinae experiences a dramatic ``spectroscopic event'' when high-excitation lines in its UV, optical, and IR spectrum disappear, and its hard X-ray and radio continuum flux crash. This periodicity has been attributed to a very eccentric binary system with a shell ejection occurring at periastron. Mid-IR images and spectra with T-ReCS are needed to measure changes in the current bolometric luminosity and to trace dust formation episodes. This will provide a direct estimate of the mass ejected. Near-IR emission lines trace related changes in the post-event wind and ionization changes in the circumstellar environment needed to test specific models for the cause of η Car's variability as it recovers from its recent ``event''. High resolution near-IR spectra with GNIRS will continue the important work of HST/STIS, investigating changes in the direct and reflected spectrum of the stellar wind, and ionization changes in the nebula. The complex kinematic structure of η Car's ejecta also holds important clues to its mass ejection history, and is essential for interpreting other data. Phoenix can provide a unique kinematic map of the complex density and time-variable ionization structure of η Car's nebula, which is our best example of the pre-explosion environment of very massive stars.

Evidence for feedback and stellar-dynamically regulated bursty star cluster formation: the case of the Orion Nebula Cluster

NASA Astrophysics Data System (ADS)

Kroupa, Pavel; Jeřábková, Tereza; Dinnbier, František; Beccari, Giacomo; Yan, Zhiqiang

2018-04-01

A scenario for the formation of multiple co-eval populations separated in age by about 1 Myr in very young clusters (VYCs, ages less than 10 Myr) and with masses in the range 600-20 000 M⊙ is outlined. It rests upon a converging inflow of molecular gas building up a first population of pre-main sequence stars. The associated just-formed O stars ionise the inflow and suppress star formation in the embedded cluster. However, they typically eject each other out of the embedded cluster within 106 yr, that is before the molecular cloud filament can be ionised entirely. The inflow of molecular gas can then resume forming a second population. This sequence of events can be repeated maximally over the life-time of the molecular cloud (about 10 Myr), but is not likely to be possible in VYCs with mass <300 M⊙, because such populations are not likely to contain an O star. Stellar populations heavier than about 2000 M⊙ are likely to have too many O stars for all of these to eject each other from the embedded cluster before they disperse their natal cloud. VYCs with masses in the range 600-2000 M⊙ are likely to have such multi-age populations, while VYCs with masses in the range 2000-20 000 M⊙ can also be composed solely of co-eval, mono-age populations. More massive VYCs are not likely to host sub-populations with age differences of about 1 Myr. This model is applied to the Orion Nebula Cluster (ONC), in which three well-separated pre-main sequences in the colour-magnitude diagram of the cluster have recently been discovered. The mass-inflow history is constrained using this model and the number of OB stars ejected from each population are estimated for verification using Gaia data. As a further consequence of the proposed model, the three runaway O star systems, AE Aur, μ Col and ι Ori, are considered as significant observational evidence for stellar-dynamical ejections of massive stars from the oldest population in the ONC. Evidence for stellar-dynamical ejections of massive stars in the currently forming population is also discussed.

Right Ventricular Structure and Function Are Associated With Incident Atrial Fibrillation: MESA-RV Study (Multi-Ethnic Study of Atherosclerosis-Right Ventricle).

PubMed

Chatterjee, Neal A; Shah, Ravi V; Murthy, Venkatesh L; Praestgaard, Amy; Shah, Sanjiv J; Ventetuolo, Corey E; Barr, R Graham; Kronmal, Richard; Lima, Joao A C; Bluemke, David A; Jerosch-Herold, Michael; Alonso, Alvaro; Kawut, Steven M

2017-01-01

Right ventricular (RV) morphology has been associated with drivers of atrial fibrillation (AF) risk, including left ventricular and pulmonary pathology, systemic inflammation, and neurohormonal activation. The aim of this study was to investigate the association between RV morphology and risk of incident AF. We interpreted cardiac magnetic resonance imaging in 4204 participants free of clinical cardiovascular disease in the MESA (Multi-Ethnic Study of Atherosclerosis). Incident AF was determined using hospital discharge records, study electrocardiograms, and Medicare claims data. The study sample (n=3819) was 61±10 years old and 47% male with 47.2% current/former smokers. After adjustment for demographics and clinical factors, including incident heart failure, higher RV ejection fraction (hazard ratio, 1.16 per SD; 95% confidence interval, 1.03-1.32; P=0.02) and greater RV mass (hazard ratio, 1.25 per SD; 95% confidence interval, 1.08-1.44; P=0.002) were significantly associated with incident AF. After additional adjustment for the respective left ventricular parameter, higher RV ejection fraction remained significantly associated with incident AF (hazard ratio, 1.15 per SD; 95% confidence interval, 1.01-1.32; P=0.04), whereas the association was attenuated for RV mass (hazard ratio, 1.16 per SD; 95% confidence interval, 0.99-1.35; P=0.07). In a subset of patients with available spirometry (n=2540), higher RV ejection fraction and mass remained significantly associated with incident AF after additional adjustment for lung function (P=0.02 for both). Higher RV ejection fraction and greater RV mass were associated with an increased risk of AF in a multiethnic population free of clinical cardiovascular disease at baseline. © 2017 American Heart Association, Inc.

Cardiac Structure and Function in Cushing's Syndrome: A Cardiac Magnetic Resonance Imaging Study

PubMed Central

Roux, Charles; Salenave, Sylvie; Kachenoura, Nadjia; Raissouni, Zainab; Macron, Laurent; Guignat, Laurence; Jublanc, Christel; Azarine, Arshid; Brailly, Sylvie; Young, Jacques; Mousseaux, Elie; Chanson, Philippe

2014-01-01

Background: Patients with Cushing's syndrome have left ventricular (LV) hypertrophy and dysfunction on echocardiography, but echo-based measurements may have limited accuracy in obese patients. No data are available on right ventricular (RV) and left atrial (LA) size and function in these patients. Objectives: The objective of the study was to evaluate LV, RV, and LA structure and function in patients with Cushing's syndrome by means of cardiac magnetic resonance, currently the reference modality in assessment of cardiac geometry and function. Methods: Eighteen patients with active Cushing's syndrome and 18 volunteers matched for age, sex, and body mass index were studied by cardiac magnetic resonance. The imaging was repeated in the patients 6 months (range 2–12 mo) after the treatment of hypercortisolism. Results: Compared with controls, patients with Cushing's syndrome had lower LV, RV, and LA ejection fractions (P < .001 for all) and increased end-diastolic LV segmental thickness (P < .001). Treatment of hypercortisolism was associated with an improvement in ventricular and atrial systolic performance, as reflected by a 15% increase in the LV ejection fraction (P = .029), a 45% increase in the LA ejection fraction (P < .001), and an 11% increase in the RV ejection fraction (P = NS). After treatment, the LV mass index and end-diastolic LV mass to volume ratio decreased by 17% (P < .001) and 10% (P = .002), respectively. None of the patients had late gadolinium myocardial enhancement. Conclusion: Cushing's syndrome is associated with subclinical biventricular and LA systolic dysfunctions that are reversible after treatment. Despite skeletal muscle atrophy, Cushing's syndrome patients have an increased LV mass, reversible upon correction of hypercortisolism. PMID:25093618

The Origin, Early Evolution and Predictability of Solar Eruptions

NASA Astrophysics Data System (ADS)

Green, Lucie M.; Török, Tibor; Vršnak, Bojan; Manchester, Ward; Veronig, Astrid

2018-02-01

Coronal mass ejections (CMEs) were discovered in the early 1970s when space-borne coronagraphs revealed that eruptions of plasma are ejected from the Sun. Today, it is known that the Sun produces eruptive flares, filament eruptions, coronal mass ejections and failed eruptions; all thought to be due to a release of energy stored in the coronal magnetic field during its drastic reconfiguration. This review discusses the observations and physical mechanisms behind this eruptive activity, with a view to making an assessment of the current capability of forecasting these events for space weather risk and impact mitigation. Whilst a wealth of observations exist, and detailed models have been developed, there still exists a need to draw these approaches together. In particular more realistic models are encouraged in order to asses the full range of complexity of the solar atmosphere and the criteria for which an eruption is formed. From the observational side, a more detailed understanding of the role of photospheric flows and reconnection is needed in order to identify the evolutionary path that ultimately means a magnetic structure will erupt.

A soft x-ray coronal mass ejection occurred on solar limb on 1998 April 23

NASA Astrophysics Data System (ADS)

Cheng, X. J.

2001-11-01

Using some data observed with SXT/HXT aboard Yohkoh and the Nobeyama Radioheliograph (NoRH) on 1998 April 23, a comprehensive study on the soft X-ray coronal mass ejection (CME) on solar SE limb shows there were two magnetic dipole sources (MDSs), one magnetic capacity belt (MCB) between MDSs, one neutral current sheet (NCS) and only a few activation sources (ASs). During the MCB was changed by the ASs into a magnetic energy belt (MEB), the material and energy both concentrated to the NCS in the course of its formation. When the MDSs were put through by the MEB, the NCS formed and the CME occurred. The matter ejected not only from the NCS, but also from the whole MEB. The expanding loop of the CME had two footprints, they were just the MDSs. The head of the expanding loop always tended to the foot point of weak source. The locus of the head was just neutral line. From this, the position of NCS also could be determined.

Impact and explosion crater ejecta, fragment size, and velocity

NASA Technical Reports Server (NTRS)

Okeefe, J. D.; Ahrens, T. J.

1983-01-01

A model was developed for the mass distribution of fragments that are ejected at a given velocity for impact and explosion craters. The model is semi-empirical in nature and is derived from (1) numerical calculations of cratering and the resultant mass versus ejection velocity, (2) observed ejecta blanket particle size distributions, (3) an empirical relationship between maximum ejecta fragment size and crater diameter and an assumption on the functional form for the distribution of fragements ejected at a given velocity. This model implies that for planetary impacts into competent rock, the distribution of fragments ejected at a given velocity are nearly monodisperse, e.g., 20% of the mass of the ejecta at a given velocity contain fragments having a mass less than 0.1 times a mass of the largest fragment moving at that velocity. Using this model, the largest fragment that can be ejected from asteroids, the moon, Mars, and Earth is calculated as a function of crater diameter. In addition, the internal energy of ejecta versus ejecta velocity is found. The internal energy of fragments having velocities exceeding the escape velocity of the moon will exceed the energy required for incipient melting for solid silicates and thus, constrains the maximum ejected solid fragment size.

Ejection of iron-bearing giant-impact fragments and the dynamical and geochemical influence of the fragment re-accretion

NASA Astrophysics Data System (ADS)

Genda, Hidenori; Iizuka, Tsuyoshi; Sasaki, Takanori; Ueno, Yuichiro; Ikoma, Masahiro

2017-07-01

The Earth was born in violence. Many giant collisions of protoplanets are thought to have occurred during the terrestrial planet formation. Here we investigated the giant impact stage by using a hybrid code that consistently deals with the orbital evolution of protoplanets around the Sun and the details of processes during giant impacts between two protoplanets. A significant amount of materials (up to several tens of percent of the total mass of the protoplanets) is ejected by giant impacts. We call these ejected fragments the giant-impact fragments (GIFs). In some of the erosive hit-and-run and high-velocity collisions, metallic iron is also ejected, which comes from the colliding protoplanets' cores. From ten numerical simulations for the giant impact stage, we found that the mass fraction of metallic iron in GIFs ranges from ∼1 wt% to ∼25 wt%. We also discussed the effects of the GIFs on the dynamical and geochemical characteristics of formed terrestrial planets. We found that the GIFs have the potential to solve the following dynamical and geochemical conflicts: (1) The Earth, currently in a near circular orbit, is likely to have had a highly eccentric orbit during the giant impact stage. The GIFs are large enough in total mass to lower the eccentricity of the Earth to its current value via their dynamical friction. (2) The concentrations of highly siderophile elements (HSEs) in the Earth's mantle are greater than what was predicted experimentally. Re-accretion of the iron-bearing GIFs onto the Earth can contribute to the excess of HSEs. In addition, Iron-bearing GIFs provide significant reducing agent that could transform primitive CO2-H2O atmosphere and ocean into more reducing H2-bearing atmosphere. Thus, GIFs are important for the origin of Earth's life and its early evolution.

Disruption of a coronal streamer by an eruptive prominence and coronal mass ejection

NASA Technical Reports Server (NTRS)

Illing, R. M. E.; Hundhausen, A. J.

1986-01-01

The coronal mass ejection of August 18, 1980 is analyzed using images from the coronagraph on the Solar Maximum Mission (SMM) satellite. The event occurred at the site of a large coronal helmet streamer and evolved into the three-part structure of a bright frontal shell, followed by a relatively dark space surrounding a bright filamentary core as seen in many mass ejections of the SMM epoch. The bright core can be identified as material from a prominence whose eruption was observed from the ground. The mass of the frontal shell is equal to that of the coronal helmet streamer, indicating that the shell is the coronal material previously in the helmet streamer, displaced and set into motion by the erupting prominence and surrounding cavity. The mass ejected in the bright core (or prominences) is estimated to be 50 percent larger than the 'coronal' material in the front loop.

The Eruption of a Small-scale Emerging Flux Rope as the Driver of an M-class Flare and of a Coronal Mass Ejection

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

Yan, X. L.; Xue, Z. K.; Wang, J. C.

Solar flares and coronal mass ejections are the most powerful explosions in the Sun. They are major sources of potentially destructive space weather conditions. However, the possible causes of their initiation remain controversial. Using high-resolution data observed by the New Solar Telescope of Big Bear Solar Observatory, supplemented by Solar Dynamics Observatory observations, we present unusual observations of a small-scale emerging flux rope near a large sunspot, whose eruption produced an M-class flare and a coronal mass ejection. The presence of the small-scale flux rope was indicated by static nonlinear force-free field extrapolation as well as data-driven magnetohydrodynamics modeling ofmore » the dynamic evolution of the coronal three-dimensional magnetic field. During the emergence of the flux rope, rotation of satellite sunspots at the footpoints of the flux rope was observed. Meanwhile, the Lorentz force, magnetic energy, vertical current, and transverse fields were increasing during this phase. The free energy from the magnetic flux emergence and twisting magnetic fields is sufficient to power the M-class flare. These observations present, for the first time, the complete process, from the emergence of the small-scale flux rope, to the production of solar eruptions.« less

Equation of State Effects on Binary Neutron Star and Neutron Star-Black Hole Merger Ejecta

NASA Astrophysics Data System (ADS)

Rizzo, Monica; Pankow, Chris; Kalogera, Vassiliki; Coughlin, Scott; Chase, Eve; Imperato, Sam

2018-01-01

Binary neutron stars (BNSs) and neutron star-black hole (NSBH) binaries are not only potential sources of gravitational waves (GWs), but also are thought to generate phenomena such as kilonova, which have proven to be difficult to catch with electromagnetic (EM) instruments. Kilonovae are believed to arise from the radioactive decay of nuclear matter ejected from NSBH and BNS mergers. As they spiral toward each other, neutron stars (NSs), composed of highly dense nuclear matter, are torn apart by their companion's gravity and eject matter. The amount of matter they eject depends sensitively on the composition of NSs, which is described by a nuclear equation of state (EOS). Using fit formulas for ejected mass from Kawaguchi et. al. (2016) and T. Dietrich and M. Ujevic (2016), for NSBH and BNS respectively, we calculate the amount of mass ejected given the initial parameters (masses, black hole spin, etc.) of NSBH and BNS systems. We then predict the distribution of ejected matter for populations of NSBH and BNS mergers, assuming a different EOS for each population. Using formulas derived from The Kilonova Handbook (Metzger, 2016), we can use the calculated ejected mass to generate light curves which, along with GW detections, can be used to place constraints on an EOS for NSs when GW detections are made. We find that the amount of ejected matter observed is distinct for most EOSs, though to draw any solid conclusions about NS composition, joint GW wave and EM counterpart detections are necessary.

Coronal mass ejections and coronal structures

NASA Technical Reports Server (NTRS)

Hildner, E.; Bassi, J.; Bougeret, J. L.; Duncan, R. A.; Gary, D. E.; Gergely, T. E.; Harrison, R. A.; Howard, R. A.; Illing, R. M. E.; Jackson, B. V.

1986-01-01

Research on coronal mass ejections (CMF) took a variety of forms, both observational and theoretical. On the observational side there were: case studies of individual events, in which it was attempted to provide the most complete descriptions possible, using correlative observations in diverse wavelengths; statistical studies of the properties CMEs and their associated activity; observations which may tell us about the initiation of mass ejections; interplanetary observations of associated shocks and energetic particles even observations of CMEs traversing interplanetary space; and the beautiful synoptic charts which show to what degree mass ejections affect the background corona and how rapidly (if at all) the corona recovers its pre-disturbance form. These efforts are described in capsule form with an emphasis on presenting pictures, graphs, and tables so that the reader can form a personal appreciation of the work and its results.

Coronal Mass Ejections Near the Sun and in the Interplanetary Medium

NASA Technical Reports Server (NTRS)

Gopalswamy, Nat

2012-01-01

Coronal mass ejections (CMEs) are the most energetic phenomenon in the heliosphere. During solar eruptions, the released energy flows out from the Sun in the form of magnetized plasma and electromagnetic radiation. The electromagnetic radiation suddenly increases the ionization content of the ionosphere, thus impacting communication and navigation systems. The plasma clouds can drive shocks that accelerate charged particles to very high energies in the interplanetary space, which pose radiation hazard to astronauts and space systems. The plasma clouds also arrive at Earth in about two days and impact Earth's magnetosphere, producing geomagnetic storms. The magnetic storms result in a number of effects including induced currents that can disrupt power grids, railroads, and underground pipelines. This lecture presents an overview of the origin, propagation, and geospace consequences of CMEs and their interplanetary counterparts.

Binaries discovered by the SPY survey. VI. Discovery of a low mass companion to the hot subluminous planetary nebula central star EGB 5 - a recently ejected common envelope?

NASA Astrophysics Data System (ADS)

Geier, S.; Napiwotzki, R.; Heber, U.; Nelemans, G.

2011-04-01

Hot subdwarf B stars (sdBs) in close binary systems are assumed to be formed via common envelope ejection. According to theoretical models, the amount of energy and angular momentum deposited in the common envelope scales with the mass of the companion. That low mass companions near or below the core hydrogen-burning limit are able to trigger the ejection of this envelope is well known. The currently known systems have very short periods ≃0.1-0.3 d. Here we report the discovery of a low mass companion (M2 > 0.14 M⊙) orbiting the sdB star and central star of a planetary nebula EGB 5 with an orbital period of 16.5 d at a minimum separation of 23 R⊙. Its long period is only just consistent with the energy balance prescription of the common envelope. The marked difference between the short and long period systems will provide strong constraints on the common envelope phase, in particular if the masses of the sdB stars can be measured accurately. Due to selection effects, the fraction of sdBs with low mass companions and similar or longer periods may be quite high. Low mass stellar and substellar companions may therefore play a significant role for the still unclear formation of hot subdwarf stars. Furthermore, the nebula around EGB 5 may be the remnant of the ejected common envelope making this binary a unique system to study this short und poorly understood phase of binary evolution. Based on observations at the Paranal Observatory of the European Southern Observatory for programmes No. 167.H-0407(A) and 71.D-0383(A). Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). Some of the data used in this work were obtained at the William Herschel Telescope (WHT) operated by the Isaac Newton Group of Telescopes (ING).

Energy and momentum analysis of the deployment dynamics of nets in space

NASA Astrophysics Data System (ADS)

Botta, Eleonora M.; Sharf, Inna; Misra, Arun K.

2017-11-01

In this paper, the deployment dynamics of nets in space is investigated through a combination of analysis and numerical simulations. The considered net is deployed by ejecting several corner masses and thanks to momentum and energy transfer from those to the innermost threads of the net. In this study, the net is modeled with a lumped-parameter approach, and assumed to be symmetrical, subject to symmetrical initial conditions, and initially slack. The work-energy and momentum conservation principles are employed to carry out centroidal analysis of the net, by conceptually partitioning the net into a system of corner masses and the net proper and applying the aforementioned principles to the corresponding centers of mass. The analysis provides bounds on the values that the velocity of the center of mass of the corner masses and the velocity of the center of mass of the net proper can individually attain, as well as relationships between these and different energy contributions. The analytical results allow to identify key parameters characterizing the deployment dynamics of nets in space, which include the ratio between the mass of the corner masses and the total mass, the initial linear momentum, and the direction of the initial velocity vectors. Numerical tools are employed to validate and interpret further the analytical observations. Comparison of deployment results with and without initial velocity of the net proper suggests that more complete and lasting deployment can be achieved if the corner masses alone are ejected. A sensitivity study is performed for the key parameters identified from the energy/momentum analysis, and the outcome establishes that more lasting deployment and safer capture (i.e., characterized by higher traveled distance) can be achieved by employing reasonably lightweight corner masses, moderate shooting angles, and low shooting velocities. A comparison with current literature on tether-nets for space debris capture confirms overall agreement on the importance and effect of the relevant inertial and ejection parameters on the deployment dynamics.

Gallium Electromagnetic (GEM) Thruster Performance Measurements

NASA Technical Reports Server (NTRS)

Thomas, Robert E.; Burton, Rodney L.; Polzin, K. A.

2009-01-01

Discharge current, terminal voltage, and mass bit measurements are performed on a coaxial gallium electromagnetic thruster at discharge currents in the range of 7-23 kA. It is found that the mass bit varies quadratically with the discharge current which yields a constant exhaust velocity of 20 km/s. Increasing the electrode radius ratio of the thruster from to 2.6 to 3.4 increases the thruster efficiency from 21% to 30%. When operating with a central gallium anode, macroparticles are ejected at all energy levels tested. A central gallium cathode ejects macroparticles when the current density exceeds 3.7 10(exp 8) A/square m . A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma. The spectra show that neutral, singly, and doubly ionized gallium species are present in the discharge, as well as annular electrode species at higher energy levels. Axial Langmuir triple probe measurements yield electron temperatures in the range of 0.8-3.8 eV and electron densities in the range of 8 x 10(exp )20 to 1.6 x 10(exp 21) m(exp -3) . Triple probe measurements suggest an exhaust plume with a divergence angle of 9 , and a completely doubly ionized plasma at the ablating thruster cathode.

Composition analyzer for microparticles using a spark ion source

NASA Technical Reports Server (NTRS)

Auer, S.; Berg, O. E.

1975-01-01

Iron microparticles were fired onto a capacitor-type microparticle detector which responded to an impact with a spark discharge. Ion currents were extracted from the spark and analyzed in a time-of-flight mass spectrometer. The mass spectra showed the elements of both detector and particle materials. The total extracted ion current was typically 10 A within a period of 100 nsec, indicating very efficient vaporization of the particle and ionization of the vapor. Potential applications include research on cosmic dust, atmospheric aerosols and cloud droplets, particles ejected by rocket or jet engines, by machining processes or by nuclear bomb explosions.

Triennial Report 2006-2009. Commission 10: Solar Activity

NASA Technical Reports Server (NTRS)

Klimchuk, James A.

2008-01-01

Commission 10 deals with solar activity in all of its forms, ranging from the smallest nanoflares to the largest coronal mass ejections. This report reviews scientific progress over the roughly two-year period ending in the middle of 2008. This has been an exciting time in solar physics, highlighted by the launches of the Hinode and STEREO missions late in 2006. The report is reasonably comprehensive, though it is far from exhaustive. Limited space prevents the inclusion of many significant results. The report is divided into following sections: Photosphere and Chromosphere; Transition Region; Corona and Coronal Heating; Coronal Jets; Flares; Coronal Mass Ejection Initiation; Global Coronal Waves and Shocks; Coronal Dimming; The Link Between Low Coronal CME signatures and Magnetic Clouds; Coronal Mass Ejections in the Heliosphere; and Coronal Mass Ejections and Space Weather. Primary authorship is indicated at the beginning of each section.

Vortex Formation in the Wake of Dark Matter Propulsion

NASA Astrophysics Data System (ADS)

Robertson, G. A.; Pinheiro, M. J.

Future spaceflight will require a new theory of propulsion; specifically one that does not require mass ejection. A new theory is proposed that uses the general view that closed currents pervade the entire universe and, in particular, there is a cosmic mechanism to expel matter to large astronomical distances involving vortex currents as seen with blazars and blackholes. At the terrestrial level, force producing vortices have been related to the motion of wings (e.g., birds, duck paddles, fish's tail). In this paper, vortex structures are shown to exist in the streamlines aft of a spaceship moving at high velocity in the vacuum. This is accomplished using the density excitation method per a modified Chameleon Cosmology model. This vortex structure is then shown to have similarities to spacetime models as Warp-Drive and wormholes, giving rise to the natural extension of Hawking and Unruh radiation, which provides the propulsive method for space travel where virtual electron-positron pairs, absorbed by the gravitational expansion forward of the spaceship emerge from an annular vortex field aft of the spaceship as real particles, in-like to propellant mass ejection in conventional rocket theory.

Searching for Biosignatures in Exoplanetary Impact Ejecta

NASA Astrophysics Data System (ADS)

Cataldi, Gianni; Brandeker, Alexis; Thébault, Philippe; Singer, Kelsi; Ahmed, Engy; de Vries, Bernard L.; Neubeck, Anna; Olofsson, Göran

2017-08-01

With the number of confirmed rocky exoplanets increasing steadily, their characterization and the search for exoplanetary biospheres are becoming increasingly urgent issues in astrobiology. To date, most efforts have concentrated on the study of exoplanetary atmospheres. Instead, we aim to investigate the possibility of characterizing an exoplanet (in terms of habitability, geology, presence of life, etc.) by studying material ejected from the surface during an impact event. For a number of impact scenarios, we estimate the escaping mass and assess its subsequent collisional evolution in a circumstellar orbit, assuming a Sun-like host star. We calculate the fractional luminosity of the dust as a function of time after the impact event and study its detectability with current and future instrumentation. We consider the possibility to constrain the dust composition, giving information on the geology or the presence of a biosphere. As examples, we investigate whether calcite, silica, or ejected microorganisms could be detected. For a 20 km diameter impactor, we find that the dust mass escaping the exoplanet is roughly comparable to the zodiacal dust, depending on the exoplanet's size. The collisional evolution is best modeled by considering two independent dust populations, a spalled population consisting of nonmelted ejecta evolving on timescales of millions of years, and dust recondensed from melt or vapor evolving on much shorter timescales. While the presence of dust can potentially be inferred with current telescopes, studying its composition requires advanced instrumentation not yet available. The direct detection of biological matter turns out to be extremely challenging. Despite considerable difficulties (small dust masses, noise such as exozodiacal dust, etc.), studying dusty material ejected from an exoplanetary surface might become an interesting complement to atmospheric studies in the future.

Searching for Biosignatures in Exoplanetary Impact Ejecta.

PubMed

Cataldi, Gianni; Brandeker, Alexis; Thébault, Philippe; Singer, Kelsi; Ahmed, Engy; de Vries, Bernard L; Neubeck, Anna; Olofsson, Göran

2017-08-01

With the number of confirmed rocky exoplanets increasing steadily, their characterization and the search for exoplanetary biospheres are becoming increasingly urgent issues in astrobiology. To date, most efforts have concentrated on the study of exoplanetary atmospheres. Instead, we aim to investigate the possibility of characterizing an exoplanet (in terms of habitability, geology, presence of life, etc.) by studying material ejected from the surface during an impact event. For a number of impact scenarios, we estimate the escaping mass and assess its subsequent collisional evolution in a circumstellar orbit, assuming a Sun-like host star. We calculate the fractional luminosity of the dust as a function of time after the impact event and study its detectability with current and future instrumentation. We consider the possibility to constrain the dust composition, giving information on the geology or the presence of a biosphere. As examples, we investigate whether calcite, silica, or ejected microorganisms could be detected. For a 20 km diameter impactor, we find that the dust mass escaping the exoplanet is roughly comparable to the zodiacal dust, depending on the exoplanet's size. The collisional evolution is best modeled by considering two independent dust populations, a spalled population consisting of nonmelted ejecta evolving on timescales of millions of years, and dust recondensed from melt or vapor evolving on much shorter timescales. While the presence of dust can potentially be inferred with current telescopes, studying its composition requires advanced instrumentation not yet available. The direct detection of biological matter turns out to be extremely challenging. Despite considerable difficulties (small dust masses, noise such as exozodiacal dust, etc.), studying dusty material ejected from an exoplanetary surface might become an interesting complement to atmospheric studies in the future. Key Words: Biosignatures-Exoplanets-Impacts-Interplanetary dust-Remote sensing. Astrobiology 17, 721-746.

Density and white light brightness in looplike coronal mass ejections - Temporal evolution

NASA Technical Reports Server (NTRS)

Steinolfson, R. S.; Hundhausen, A. J.

1988-01-01

Three ambient coronal models suitable for studies of time-dependent phenomena were used to investigate the propagation of coronal mass ejections initiated in each atmosphere by an identical energy source. These models included those of a static corona with a dipole magnetic field, developed by Dryer et al. (1979); a steady polytropic corona with an equatorial coronal streamer, developed by Steinolfson et al. (1982); and Steinolfson's (1988) model of heated corona with an equatorial coronal streamer. The results indicated that the first model does not adequately represent the general characteristics of observed looplike mass ejections, and the second model simulated only some of the observed features. Only the third model, which included a heating term and a streamer, was found to yield accurate simulation of the mess ejection observations.

The size distributions of fragments ejected at a given velocity from impact craters

NASA Technical Reports Server (NTRS)

O'Keefe, John D.; Ahrens, Thomas J.

1987-01-01

The mass distribution of fragments that are ejected at a given velocity for impact craters is modeled to allow extrapolation of laboratory, field, and numerical results to large scale planetary events. The model is semi-empirical in nature and is derived from: (1) numerical calculations of cratering and the resultant mass versus ejection velocity, (2) observed ejecta blanket particle size distributions, (3) an empirical relationship between maximum ejecta fragment size and crater diameter, (4) measurements and theory of maximum ejecta size versus ejecta velocity, and (5) an assumption on the functional form for the distribution of fragments ejected at a given velocity. This model implies that for planetary impacts into competent rock, the distribution of fragments ejected at a given velocity is broad, e.g., 68 percent of the mass of the ejecta at a given velocity contains fragments having a mass less than 0.1 times a mass of the largest fragment moving at that velocity. The broad distribution suggests that in impact processes, additional comminution of ejecta occurs after the upward initial shock has passed in the process of the ejecta velocity vector rotating from an initially downward orientation. This additional comminution produces the broader size distribution in impact ejecta as compared to that obtained in simple brittle failure experiments.

High-bandwidth continuous-flow arc furnace

DOEpatents

Hardt, David E.; Lee, Steven G.

1996-01-01

A high-bandwidth continuous-flow arc furnace for stream welding applications includes a metal mass contained in a crucible having an orifice. A power source charges an electrode for generating an arc between the electrode and the mass. The arc heats the metal mass to a molten state. A pressurized gas source propels the molten metal mass through the crucible orifice in a continuous stream. As the metal is ejected, a metal feeder replenishes the molten metal bath. A control system regulates the electrode current, shielding gas pressure, and metal source to provide a continuous flow of molten metal at the crucible orifice. Independent control over the electrode current and shield gas pressure decouples the metal flow temperature and the molten metal flow rate, improving control over resultant weld characteristics.

High-bandwidth continuous-flow arc furnace

DOEpatents

Hardt, D.E.; Lee, S.G.

1996-08-06

A high-bandwidth continuous-flow arc furnace for stream welding applications includes a metal mass contained in a crucible having an orifice. A power source charges an electrode for generating an arc between the electrode and the mass. The arc heats the metal mass to a molten state. A pressurized gas source propels the molten metal mass through the crucible orifice in a continuous stream. As the metal is ejected, a metal feeder replenishes the molten metal bath. A control system regulates the electrode current, shielding gas pressure, and metal source to provide a continuous flow of molten metal at the crucible orifice. Independent control over the electrode current and shield gas pressure decouples the metal flow temperature and the molten metal flow rate, improving control over resultant weld characteristics. 4 figs.

COSIE: The Coronal Spectrographic Imager in the EUV

NASA Technical Reports Server (NTRS)

Savage, Sabrina; Golub, Leon; Deluca, Ed

2017-01-01

COSIE is a solar-observing instrument (currently proposed for mounting onto the ISS) which obtains wide field images of the corona and full Sun spectral images with high sensitivity and rapid cadence. The primary purpose of the instrument is to constrain the global field topology and to track coronal mass ejections from the disk through the inner heliosphere.

Geomagnetic response of interplanetary coronal mass ejections in the Earth's magnetosphere

NASA Astrophysics Data System (ADS)

Badruddin; Mustajab, F.; Derouich, M.

2018-05-01

A coronal mass ejections (CME) is the huge mass of plasma with embedded magnetic field ejected abruptly from the Sun. These CMEs propagate into interplanetary space with different speed. Some of them hit the Earth's magnetosphere and create many types of disturbances; one of them is the disturbance in the geomagnetic field. Individual geomagnetic disturbances differ not only in their magnitudes, but the nature of disturbance is also different. It is, therefore, desirable to understand these differences not only to understand the physics of geomagnetic disturbances but also to understand the properties of solar/interplanetary structures producing these disturbances of different magnitude and nature. In this work, we use the spacecraft measurements of CMEs with distinct magnetic properties propagating in the interplanetary space and generating disturbances of different levels and nature. We utilize their distinct plasma and field properties to search for the interplanetary parameter(s) playing important role in influencing the geomagnetic response of different coronal mass ejections.

Inappropriate left ventricular mass and poor outcomes in patients with angina pectoris and normal ejection fraction.

PubMed

Huang, Bao-Tao; Peng, Yong; Liu, Wei; Zhang, Chen; Huang, Fang-Yang; Wang, Peng-Ju; Zuo, Zhi-Liang; Liao, Yan-Biao; Chai, Hua; Li, Qiao; Zhao, Zhen-Gang; Luo, Xiao-Lin; Ren, Xin; Huang, Kai-Sen; Meng, Qing-Tao; Chen, Chi; Huang, De-Jia; Chen, Mao

2015-03-01

Although inappropriate left ventricular mass has been associated with clustered cardiac geometric and functional abnormalities, its predictive value in patients with coronary artery disease is still unknown. This study examined the association of inappropriate left ventricular mass with clinical outcomes in patients with angina pectoris and normal ejection fraction. Consecutive patients diagnosed with angina pectoris whose ejection fraction was normal were recruited from 2008 to 2012. Inappropriate left ventricular mass was determined when the ratio of actual left ventricular mass to the predicted one exceeded 150%. The primary endpoint was a composite of all-cause death, nonfatal myocardial infarction, and nonfatal stroke. Clinical outcomes between the inappropriate and appropriate left ventricular mass group were compared before and after propensity matching. Of the total of 1515 participants, 18.3% had inappropriate left ventricular mass. Patients with inappropriate left ventricular mass had a higher composite event rate compared with those with appropriate left ventricular mass (11.2 vs. 6.6%, P=0.010). Multivariate Cox regression analyses showed that inappropriate left ventricular mass was an independent risk factor for adverse events (adjusted hazard ratio, 1.59; 95% confidence interval, 1.03-2.45; P=0.035). The worse outcome in patients with inappropriate left ventricular mass was further validated in a propensity matching cohort and patients with the traditional definition of left ventricular hypertrophy. Inappropriate left ventricular mass was associated with an increased risk of adverse events in patients with angina pectoris and normal ejection fraction.

A composition analyzer for microparticles using a spark ion source. [using time of flight spectrometers

NASA Technical Reports Server (NTRS)

Auer, S. O.; Berg, O. E.

1975-01-01

Iron microparticles were fired onto a capacitor-type microparticle detector which responded to an impact with a spark discharge. Ion currents were extracted from the spark and analyzed in a time-of-flight mass spectrometer. The mass spectra showed the element of both detector and particle materials. The total extracted ion currents was typically 10A within a period of 100ns, indicating very efficient vaporization of the particle and ionization of the vapor. Potential applications include research on cosmic dust, atmospheric aerosols and cloud droplets, particles ejected by rocket or jet engines, by machining processes, or by nuclear bomb explosions.

Do we understand coronal mass ejections yet?

NASA Technical Reports Server (NTRS)

Hildner, Ernest

1986-01-01

Though many more coronal mass ejections (CMEs) were observed, and though much more has been learned about them during the Solar Maximum Analysis period, they are not yet fully understood. A few recent observational results are reviewed; conclusions and implications drawn from these observations are presented. An emerging picture of the magnetic character of CMEs is sketched; the variations of CMEs' frequency and latitudes over most of a solar cycle are shown. A strong caution about the present lack of concensus on the definition of CMEs is illustrated with examples of the consequences of using different definitions. Finally, some remaining questions about coronal mass ejections are posed.

Deflections of Fast Coronal Mass Ejections and the Properties of Associated Solar Energetic Particle Events (POSTPRINT)

DTIC Science & Technology

2012-09-20

coronal mass ejection (CME) source regions can deflect fast CMEs from their expected trajectories in space, explaining the appearance of driverless shocks...the appearance of driverless shocks at 1 AU from CMEs ejected near solar central meridian (CM). This suggests that SEP events originating in CME-driven...interplanetary CME (ICME) drivers. Most such driverless shocks occur only from CMEs near the solar limbs, but these disk-center CMEs were located adjacent to CHs

Matrix-array 3-dimensional echocardiographic assessment of volumes, mass, and ejection fraction in young pediatric patients with a functional single ventricle: a comparison study with cardiac magnetic resonance.

PubMed

Soriano, Brian D; Hoch, Martin; Ithuralde, Alejandro; Geva, Tal; Powell, Andrew J; Kussman, Barry D; Graham, Dionne A; Tworetzky, Wayne; Marx, Gerald R

2008-04-08

Quantitative assessment of ventricular volumes and mass in pediatric patients with single-ventricle physiology would aid clinical management, but it is difficult to obtain with 2-dimensional echocardiography. The purpose of the present study was to compare matrix-array 3-dimensional echocardiography (3DE) measurements of single-ventricle volumes, mass, and ejection fraction with those measured by cardiac magnetic resonance (CMR) in young patients. Twenty-nine patients (median age, 7 months) with a functional single ventricle undergoing CMR under general anesthesia were prospectively enrolled. The 3DE images were acquired at the conclusion of the CMR. Twenty-seven of 29 3DE data sets (93%) were optimal for 3DE assessment. Two blinded and independent observers performed 3DE measurements of volume, mass, and ejection fraction. The 3DE end-diastolic volume correlated well (r=0.96) but was smaller than CMR by 9% (P<0.01), and 3DE ejection fraction was smaller than CMR by 11% (P<0.01). There was no significant difference in measurements of end-systolic volume and mass. The 3DE interobserver differences for mass and volumes were not significant except for ejection fraction (8% difference; P<0.05). Intraobserver differences were not significant. In young pediatric patients with a functional single ventricle, matrix-array 3DE measurements of mass and volumes compare well with those obtained by CMR. 3DE will provide an important modality for the serial analysis of ventricular size and performance in young patients with functional single ventricles.

Ejection and Lofting of Dust from Hypervelocity Impacts on the Moon

NASA Astrophysics Data System (ADS)

Hermalyn, B.; Schultz, P. H.

2011-12-01

Hypervelocity impact events mobilize and redistribute fine-grained regolith dust across the surfaces of planetary bodies. The ejecta mass-velocity distribution controls the location and emplacement of these materials. The current flux of material falling on the moon is dominated by small bolides and should cause frequent impacts that eject dust at high speeds. For example, approximately 25 LCROSS-sized (~20-30m diameter) craters are statistically expected to be formed naturally on the moon during any given earth year. When scaled to lunar conditions, the high-speed component of ejecta from hypervelocity impacts can be lofted for significant periods of time (as evidenced by the LCROSS mission results, c.f., Schultz, et al., 2010, Colaprete, et al., 2010). Even at laboratory scales, ejecta can approach orbital velocities; the higher impact speeds and larger projectiles bombarding the lunar surface may permit a significant portion of material to be launched closer to escape velocity. When these ejecta return to the surface (or encounter local topography), they impact at hundreds of meters per second or faster, thereby "scouring" the surface with low mass oblique impacts. While these high-speed ejecta represent only a small fraction of the total ejected mass, the lofting and subsequent ballistic return of this dust has the highest mobilization potential and will be directly applicable to the upcoming LADEE mission. A suite of hypervelocity impact experiments into granular materials was performed at the NASA Ames Vertical Gun Range (AVGR). This study incorporates both canonical sand targets and air-fall pumice dust to simulate the mechanical properties of lunar regolith. The implementation of a Particle Tracking Velocimetry (PTV) technique permits non-intrusive measurement of the ejecta velocity distribution within the ejecta curtain by following the path of individual ejecta particles. The PTV system developed at the AVGR uses a series of high-speed cameras (ranging from 11,000 to 500,000 frames per second) to allow measurement of particle velocity over the large dynamic range required for early-time, high-speed components of ejecta. Preliminary results for impacts into sand (Hermalyn and Schultz, 2010, 2011) reveal that early in the cratering process, ejection velocities are higher than assumed by dimensional scaling laws (Housen, et al., 1983). Moreover, the ejection angles of this early-time component are initially low (~30°) and gradually increase to reach nominal ejection angles (~45° for impacts into sand). In this study, we assess the expected ejecta velocities on the moon from the current impact flux and the possible effects of the secondary impacts of ejecta dust particles. By convolving these ejecta measurements with the lunar impact flux rate, an estimate can be derived for the amount and ballistic flight time of dust lofted above the surface of the moon over a given year.

On the deficit problem of mass and energy of solar coronal mass ejections connected with interplanetary shocks

NASA Technical Reports Server (NTRS)

Ivanchuk, V. I.; Pishkalo, N. I.

1995-01-01

Mean values of a number of parameters of the most powerful coronal mass ejections (CMEs) and interplanetary shocks generated by these ejections are estimated using an analysis of data obtained by the cosmic coronagraphs and spacecrafts, and geomagnetic storm measurements. It was payed attention that the shock mass and mechanical energy, averaging 5 x 10(exp 16) grm and 2 x 10(exp 32) erg respectively, are nearly 10 times larger than corresponding parameters of the ejections. So, the CME energy deficit problem seems to exist really. To solve this problem one can make an assumption that the process of the mass and energy growth of CMEs during their propagation out of the Sun observed in the solar corona is continued in supercorona too up to distances of 10-30 solar radii. This assumption is confirmed by the data analysis of five events observed using zodiacal light photometers of the HELIOS- I and HELIOS-2 spacecrafts. The mass growth rate is estimated to be equal to (1-7) x 10(exp 11) grm/sec. It is concluded that the CME contribution to mass and energy flows in the solar winds probably, is larger enough than the value of 3-5% adopted usually.

Double-core evolution. 5: Three-dimensional effects in the merger of a red giant with a dwarf companion

NASA Technical Reports Server (NTRS)

Terman, James L.; Taam, Ronald E.; Hernquist, Lars

1994-01-01

The evolution of the common envelope phase of a binary system consisting of a 4.67 solar mass red giant and a 0.94 solar mass dwarf is studied using smoothed particle hydrodynamics. We demonstrate that the three-dimensional effects associated with the gravitational tidal torques lead to a rapid decay of the orbit on timescales approximately less than 1 yr. The relative orbit of the two cores in the common envelope is initally eccentric and tends to circularize as the orbital separation of the two cores decreases. The angular momentum lost from the orbital motion is distributed throughout the common envelope, and the double core does not evolve to a state of co-rotation for the evolutionary time followed. The energy dissipated from the relative orbit and deposited in the common envelope results in the ejection of approximately 13% of the mass of the envelope. The mass is ejected in all directions, but there is a preference for mass ejection in the orbital plane of the binary system. For example, approximately 80% of the ejected mass lies within 30 deg of the binary orbital plane. Because gravitational forces are long range, most of the energy and angular momentum is imparted to a small fraction of the common envelope resulting in an efficiency of the mass ejection process of approximately 15%. The core of the red giant executes significant displacement with respect to the center of mass of the system and contributes nearly equally to the total energy dissipation rate during the latter phases of the evolution. The degree of departure from synchronism of the initial binary system can be an important property of the system which can affect the outcome of the common envelope phase.

Coronal Mass Ejections in September 2017 from Monitoring of Interplanetary Scintillations with the Large Phased Array of the Lebedev Institute of Physics

NASA Astrophysics Data System (ADS)

Chashei, I. V.; Tyul'bashev, S. A.; Shishov, V. I.; Subaev, I. A.

2018-05-01

Results of monitoring of interplanetary scintillations with the Large Phased Array of the Pushchino Radio AstronomyObservatory at 111 MHz during a period of flare activity of the Sun in the first ten days of September 2017 are presented. Enhancements of scintillations associated with interplanetary coronal mass ejections propagating after limb flares have been recorded. The propagation velocities are estimated to be about 2000 km/s for an ejection on September 7 and about 1000 km/s for an ejection on September 6. It is shown that, during the propagation from the Sun, the lateral part of the ejections decelerates faster than its leading part. Night-time enhancements of second-timescale scintillations during periods of high geomagnetic activity have an ionospheric origin.

Snowy CME

NASA Image and Video Library

2017-12-08

A solar flare associated with the coronal mass ejection seen in this image generated a flurry of fast-moving solar protons. As each one hits the CCD camera on SOHO, it produces a brief snow-like speckle in the image. Credit: NASA/SOHO CME WEEK: What To See in CME Images Two main types of explosions occur on the sun: solar flares and coronal mass ejections. Unlike the energy and x-rays produced in a solar flare – which can reach Earth at the speed of light in eight minutes – coronal mass ejections are giant, expanding clouds of solar material that take one to three days to reach Earth. Once at Earth, these ejections, also called CMEs, can impact satellites in space or interfere with radio communications. During CME WEEK from Sept. 22 to 26, 2014, we explore different aspects of these giant eruptions that surge out from the star we live with. When a coronal mass ejection blasts off the sun, scientists rely on instruments called coronagraphs to track their progress. Coronagraphs block out the bright light of the sun, so that the much fainter material in the solar atmosphere -- including CMEs -- can be seen in the surrounding space. CMEs appear in these images as expanding shells of material from the sun's atmosphere -- sometimes a core of colder, solar material (called a filament) from near the sun's surface moves in the center. But mapping out such three-dimensional components from a two-dimensional image isn't easy. Watch the slideshow to find out how scientists interpret what they see in CME pictures. The images in the slideshow are from the three sets of coronagraphs NASA currently has in space. One is on the joint European Space Agency and NASA Solar and Heliospheric Observatory, or SOHO. SOHO launched in 1995, and sits between Earth and the sun about a million miles away from Earth. The other two coronagraphs are on the two spacecraft of the NASA Solar Terrestrial Relations Observatory, or STEREO, mission, which launched in 2006. The two STEREO spacecraft are both currently viewing the far side of the sun. Together these instruments help scientists create a three-dimensional model of any CME as its journey unfolds through interplanetary space. Such information can show why a given characteristic of a CME close to the sun might lead to a given effect near Earth, or any other planet in the solar system...NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

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

Belov, Mikhail E.; Anderson, Gordon A.; Smith, Richard D.

Data-dependent selective external ion ejection with improved resolution is demonstrated with a 3.5 tesla FTICR instrument employing DREAMS (Dynamic Range Enhancement Applied to Mass Spectrometry) technology. To correct for the fringing rf-field aberrations each rod of the selection quadrupole has been segmented into three sections, so that ion excitation and ejection was performed by applying auxiliary rf-only waveforms in the region of the middle segments. Two different modes of external ion trapping and ejection were studied with the mixtures of model peptides and a tryptic digest of bovine serum albumin. A mass resolution of about 100 has been attained formore » rf-only dipolar ejection in a quadrupole operating at a Mathieu parameter q of{approx} 0.45. LC-ESI-DREAMS-FTICR analysis of a 0.1 mg/mL solution of bovine serum albumin digest resulted in detection of 82 unique tryptic peptides with mass measurement errors lower than 5 ppm, providing 100% sequence coverage of the protein.« less

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

Belov, Mikhail E.; Anderson, Gordon A.; Smith, Richard D.

Data-dependent selective external ion ejection with improved resolution is demonstrated with a 3.5 tesla FTICR instrument employing DREAMS (Dynamic Range Enhancement Applied to Mass Spectrometry) technology. To correct for the fringing rf-field aberrations each rod of the selection quadrupole has been segmented into three sections, so that ion excitation and ejection was performed by applying auxiliary rf-only waveforms in the region of the middle segments. Two different modes of external ion trapping and ejection were studied with the mixtures of model peptides and a tryptic digest of bovine serum albumin. A mass resolution of about 100 had been attained formore » rf-only dipolar ejection in a quadrupole operating at a Mathieu parameter q of ~0.45. LC-ESI-DREAMS-FTICR analysis of a 0.1 mg/mL solution of bovine serum albumin digest resulted in detection of 82 unique tryptic peptides with mass measurement errors lower than 5 ppm, providing 100 % sequence coverage of the protein.« less

Implications of the interstellar object 1I/'Oumuamua for planetary dynamics and planetesimal formation

NASA Astrophysics Data System (ADS)

Raymond, Sean N.; Armitage, Philip J.; Veras, Dimitri; Quintana, Elisa V.; Barclay, Thomas

2018-05-01

'Oumuamua, the first bona fide interstellar planetesimal, was discovered passing through our Solar system on a hyperbolic orbit. This object was likely dynamically ejected from an extrasolar planetary system after a series of close encounters with gas giant planets. To account for 'Oumuamua's detection, simple arguments suggest that ˜1 M⊕ of planetesimals are ejected per solar mass of Galactic stars. However, that value assumes mono-sized planetesimals. If the planetesimal mass distribution is instead top-heavy, the inferred mass in interstellar planetesimals increases to an implausibly high value. The tension between theoretical expectations for the planetesimal mass function and the observation of 'Oumuamua can be relieved if a small fraction ({˜ } 0.1-1 {per cent}) of planetesimals are tidally disrupted on the pathway to ejection into 'Oumuamua-sized fragments. Using a large suite of simulations of giant planet dynamics including planetesimals, we confirm that 0.1-1 per cent of planetesimals pass within the tidal disruption radius of a gas giant on their pathway to ejection. 'Oumuamua may thus represent a surviving fragment of a disrupted planetesimal. Finally, we argue that an asteroidal composition is dynamically disfavoured for 'Oumuamua, as asteroidal planetesimals are both less abundant and ejected at a lower efficiency than cometary planetesimals.

R144: a very massive binary likely ejected from R136 through a binary-binary encounter

NASA Astrophysics Data System (ADS)

Oh, Seungkyung; Kroupa, Pavel; Banerjee, Sambaran

2014-02-01

R144 is a recently confirmed very massive, spectroscopic binary which appears isolated from the core of the massive young star cluster R136. The dynamical ejection hypothesis as an origin for its location is claimed improbable by Sana et al. due to its binary nature and high mass. We demonstrate here by means of direct N-body calculations that a very massive binary system can be readily dynamically ejected from an R136-like cluster, through a close encounter with a very massive system. One out of four N-body cluster models produces a dynamically ejected very massive binary system with a mass comparable to R144. The system has a system mass of ≈355 M⊙ and is located at 36.8 pc from the centre of its parent cluster, moving away from the cluster with a velocity of 57 km s-1 at 2 Myr as a result of a binary-binary interaction. This implies that R144 could have been ejected from R136 through a strong encounter with another massive binary or single star. In addition, we discuss all massive binaries and single stars which are ejected dynamically from their parent cluster in the N-body models.

IR Variability of Eta Carinae

NASA Astrophysics Data System (ADS)

Smith, Nathan

2007-02-01

Every 5.5 years, η Carinae experiences a dramatic ``spectroscopic event'' when high-excitation lines in its UV, optical, and IR spectrum disappear, and its hard X-ray and radio continuum flux crash. This periodicity has been attributed to an eccentric binary system with a shell ejection occurring at periastron. In addition, η Car shows long term changes as it is still recovering from its giant 19th century outburst. Both types of variability are directly linked to the current mass-loss rate and dust formation in its wind. Mid-IR images and spectra with T-ReCS provide a direct measure of changes in the current bolometric luminosity and trace dust formation episodes. This will provide a direct measurement of the mass ejected. Near-IR emission lines trace related changes in the post-event wind and ionization changes in the circumstellar environment needed to test specific models for the cause of η Car's variability as it recovers from its recent ``event''. High resolution near-IR spectra with GNIRS will continue the important work of HST/STIS, investigating changes in the direct and reflected spectrum of the stellar wind, and ionization changes in the nebula.

Simulations of Flare Reconnection in Breakout Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

DeVore, C. Richard; Karpen, J. T.; Antiochos, S. K.

2009-05-01

We report 3D MHD simulations of the flare reconnection in the corona below breakout coronal mass ejections (CMEs). The initial setup is a single bipolar active region imbedded in the global-scale background dipolar field of the Sun, forming a quadrupolar magnetic configuration with a coronal null point. Rotational motions applied to the active-region polarities at the base of the atmosphere introduce shear across the polarity inversion line (PIL). Eventually, the magnetic stress and energy reach the critical threshold for runaway breakout reconnection, at which point the sheared core field erupts outward at high speed. The vertical current sheet formed by the stretching of the departing sheared field suffers reconnection that reforms the initial low-lying arcade across the PIL, i.e., creates the flare loops. Our simulation model, the Adaptively Refined MHD Solver, exploits local grid refinement to resolve the detailed structure and evolution of the highly dynamic current sheet. We are analyzing the numerical experiments to identify and interpret observable signatures of the flare reconnection associated with CMEs, e.g., the flare loops and ribbons, coronal jets and shock waves, and possible origins of solar energetic particles. This research was supported by NASA and ONR.

Study of the Source Regions of Coronal Mass Ejections Using Yohkoh SXT Data

NASA Technical Reports Server (NTRS)

Webb, David F.; Kahler, Stephen W.

1997-01-01

The scientific objective of the program was to better understand how CMEs (Coronal Mass Ejections) are initiated at the sun by examining structures on the disk which are related to the origins of CMEs. CMEs represent important disruptions of large-scale structures of closed magnetic fields in the corona, and result in significant disturbances of the interplanetary medium and near-Earth space. The program pertained to NASA's objectives of understanding the physics of solar activity and the structured and evolution of the corona, and the results are being applied to understanding CMEs currently being observed by SOHO near the sun and by WIND and Ulysses in the heliosphere. Three general areas of research were pursued in the program. One was to use Yohkoh soft X-ray telescope (SXT) images of eruptive events visible against the solar disk to examine the coronal structures and the boundaries of the large-scale magnetic fields considered to be involved in coronal mass ejections (CMEs). The second area involved a survey and study of SXT X-ray arcade events which exhibit dimming, or the possible depletion of coronal material above and possibly before onset of the bright long-duration event (LDE). Finally, we studied the SXT data during periods when white light CMEs were observed the HAO Mauna Loa K-coronameter and, conversely, we examined the white light data during periods when expanding X-ray loops were observed at the limb.

Disruption of coronal magnetic field arcades

NASA Technical Reports Server (NTRS)

Mikic, Zoran; Linker, Jon A.

1994-01-01

The ideal and resistive properties of isolated large-scale coronal magnetic arcades are studied using axisymmetric solutions of the time-dependent magnetohydrodynamic (MHD) equations in spherical geometry. We examine how flares and coronal mass ejections may be initiated by sudden disruptions of the magnetic field. The evolution of coronal arcades in response to applied shearing photospheric flows indicates that disruptive behavior can occur beyond a critical shear. The disruption can be traced to ideal MHD magnetic nonequilibrium. The magnetic field expands outward in a process that opens the field lines and produces a tangential discontinuity in the magnetic field. In the presence of plasma resistivity, the resulting current sheet is the site of rapid reconnection, leading to an impulsive release of magnetic energy, fast flows, and the ejection of a plasmoid. We relate these results to previous studies of force-free fields and to the properties of the open-field configuration. We show that the field lines in an arcade are forced open when the magnetic energy approaches (but is still below) the open-field energy, creating a partially open field in which most of the field lines extend away from the solar surface. Preliminary application of this model to helmet streamers indicates that it is relevant to the initiation of coronal mass ejections.

Radio Astronomers Get Their First Glimpse of Powerful Solar Storm

NASA Astrophysics Data System (ADS)

2001-08-01

Astronomers have made the first radio-telescope images of a powerful coronal mass ejection on the Sun, giving them a long-sought glimpse of hitherto unseen aspects of these potentially dangerous events. "These observations are going to provide us with a new and unique tool for deciphering the mechanisms of coronal mass ejections and how they are related to other solar events," said Tim Bastian, an astronomer at the National Science Foundation's National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia. Radio image of coronal mass ejection; circle indicates the size and location of the Sun. White dots are where radio spectral measurements were made. Bastian, along with Monique Pick, Alain Kerdraon and Dalmiro Maia of the Paris Observatory, and Angelos Vourlidas of the Naval Research Laboratory in Washington, D.C., used a solar radio telescope in Nancay, France, to study a coronal mass ejection that occurred on April 20, 1998. Their results will be published in the September 1 edition of the Astrophysical Journal Letters. Coronal mass ejections are powerful magnetic explosions in the Sun's corona, or outer atmosphere, that can blast billions of tons of charged particles into interplanetary space at tremendous speeds. If the ejection is aimed in the direction of Earth, the speeding particles interact with our planet's magnetic field to cause auroral displays, radio-communication blackouts, and potentially damage satellites and electric-power systems. "Coronal mass ejections have been observed for many years, but only with visible-light telescopes, usually in space. While previous radio observations have provided us with powerful diagnostics of mass ejections and associated phenomena in the corona, this is the first time that one has been directly imaged in wavelengths other than visible light," Bastian said. "These new data from the radio observations give us important clues about how these very energetic events work," he added. The radio images show an expanding set of loops similar to the loops seen at visible wavelengths. The radio loops, astronomers believe, indicate regions where electrons are being accelerated to nearly the speed of light at about the time the ejection process is getting started. The same ejection observed by the radio telescope also was observed by orbiting solar telescopes. Depending on what later radio observations show, the solar studies may reveal new insights into the physics of other astronomical phenomena. For example, shocks in the corona and the interplanetary medium accelerate electrons and ions, a process believed to occur in supernova remnants - the expanding debris from stellar explosions. The electrons also may be accelerated by processes associated with magnetic reconnection, a process that occurs in the Earth's magnetosphere. "The Sun is an excellent physics laboratory, and what it teaches us can then help us understand other astrophysical phenomena in the universe," Bastian said. The radio detection of a coronal mass ejection also means that warning of the potentially dangerous effects of these events could come from ground-based radio telescopes, rather than more-expensive orbiting observatories. "With solar radio telescopes strategically placed at three or four locations around the world, coronal mass ejections could be detected 24 hours a day to provide advance warning," Bastian said. The Nancay station for radio astronomy is a facility of the Paris Observatory. The Nancay Radioheliograph is funded by the French Ministry of Education, the Centre National de la Recherche Scientifique, and by the Region Centre. This research has also been supported by the Centre National d'Etudes Spatiales. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Radio Emmision during the interaction of two Interplanetary Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Lara, Alejandro; Niembro, Tatiana; González, Ricardo

2016-07-01

We show that some sporadic radio emission observed by the WIND/WAVES experiment in the decametric/kilometric bands are due to the interaction of two interplanetary Coronal Mass Ejections. We have performed hydrodynamic simulations of the evolution of two consecutive Coronal Mass ejections in the interplanetary medium. With these simulations it is possible to follow the density evolution of the merged structure, and therefore, compute the frequency limits of the possible plasma emission. We study four well documented ICME interaction events, and found radio emission at the time and frequencies predicted by the simulations. This emission may help to anticipate the complexity of the merged region before it reaches one AU.

Eddy-Current Inspection Of Tab Seals On Beverage Cans

NASA Technical Reports Server (NTRS)

Bar-Cohen, Yoseph

1994-01-01

Eddy-current inspection system monitors tab seals on beverage cans. Device inspects all cans at usual production rate of 1,500 to 2,000 cans per minute. Automated inspection of all units replaces visual inspection by microscope aided by mass spectrometry. System detects defects in real time. Sealed cans on conveyor pass near one of two coils in differential eddy-current probe. Other coil in differential eddy-current probe positioned near stationary reference can on which tab seal is known to be of acceptable quality. Signal of certain magnitude at output of probe indicates defective can, automatically ejected from conveyor.

THE PROPERTIES OF DYNAMICALLY EJECTED RUNAWAY AND HYPER-RUNAWAY STARS

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

Perets, Hagai B.; Subr, Ladislav

2012-06-01

Runaway stars are stars observed to have large peculiar velocities. Two mechanisms are thought to contribute to the ejection of runaway stars, both of which involve binarity (or higher multiplicity). In the binary supernova scenario, a runaway star receives its velocity when its binary massive companion explodes as a supernova (SN). In the alternative dynamical ejection scenario, runaway stars are formed through gravitational interactions between stars and binaries in dense, compact clusters or cluster cores. Here we study the ejection scenario. We make use of extensive N-body simulations of massive clusters, as well as analytic arguments, in order to characterizemore » the expected ejection velocity distribution of runaway stars. We find that the ejection velocity distribution of the fastest runaways (v {approx}> 80 km s{sup -1}) depends on the binary distribution in the cluster, consistent with our analytic toy model, whereas the distribution of lower velocity runaways appears independent of the binaries' properties. For a realistic log constant distribution of binary separations, we find the velocity distribution to follow a simple power law: {Gamma}(v){proportional_to}v{sup -8/3} for the high-velocity runaways and v{sup -3/2} for the low-velocity ones. We calculate the total expected ejection rates of runaway stars from our simulated massive clusters and explore their mass function and their binarity. The mass function of runaway stars is biased toward high masses and strongly depends on their velocity. The binarity of runaways is a decreasing function of their ejection velocity, with no binaries expected to be ejected with v > 150 km s{sup -1}. We also find that hyper-runaways with velocities of hundreds of km s{sup -1} can be dynamically ejected from stellar clusters, but only at very low rates, which cannot account for a significant fraction of the observed population of hyper-velocity stars in the Galactic halo.« less

Experimental Characterization of Secular Frequency Scanning in Ion Trap Mass Spectrometers

NASA Astrophysics Data System (ADS)

Snyder, Dalton T.; Pulliam, Christopher J.; Wiley, Joshua S.; Duncan, Jason; Cooks, R. Graham

2016-07-01

Secular frequency scanning is implemented and characterized using both a benchtop linear ion trap and a miniature rectilinear ion trap mass spectrometer. Separation of tetraalkylammonium ions and those from a mass calibration mixture and from a pesticide mixture is demonstrated with peak widths approaching unit resolution for optimized conditions using the benchtop ion trap. The effects on the spectra of ion trap operating parameters, including waveform amplitude, scan direction, scan rate, and pressure are explored, and peaks at black holes corresponding to nonlinear (higher-order field) resonance points are investigated. Reverse frequency sweeps (increasing mass) on the Mini 12 are shown to result in significantly higher ion ejection efficiency and superior resolution than forward frequency sweeps that decrement mass. This result is accounted for by the asymmetry in ion energy absorption profiles as a function of AC frequency and the shift in ion secular frequency at higher amplitudes in the trap due to higher order fields. We also found that use of higher AC amplitudes in forward frequency sweeps biases ions toward ejection at points of higher order parametric resonance, despite using only dipolar excitation. Higher AC amplitudes also increase peak width and decrease sensitivity in both forward and reverse frequency sweeps. Higher sensitivity and resolution were obtained at higher trap pressures in the secular frequency scan, in contrast to conventional resonance ejection scans, which showed the opposite trend in resolution on the Mini 12. Mass range is shown to be naturally extended in secular frequency scanning when ejecting ions by sweeping the AC waveform through low frequencies, a method which is similar, but arguably superior, to the more usual method of mass range extension using low q resonance ejection.

Experimental Characterization of Secular Frequency Scanning in Ion Trap Mass Spectrometers.

PubMed

Snyder, Dalton T; Pulliam, Christopher J; Wiley, Joshua S; Duncan, Jason; Cooks, R Graham

2016-07-01

Secular frequency scanning is implemented and characterized using both a benchtop linear ion trap and a miniature rectilinear ion trap mass spectrometer. Separation of tetraalkylammonium ions and those from a mass calibration mixture and from a pesticide mixture is demonstrated with peak widths approaching unit resolution for optimized conditions using the benchtop ion trap. The effects on the spectra of ion trap operating parameters, including waveform amplitude, scan direction, scan rate, and pressure are explored, and peaks at black holes corresponding to nonlinear (higher-order field) resonance points are investigated. Reverse frequency sweeps (increasing mass) on the Mini 12 are shown to result in significantly higher ion ejection efficiency and superior resolution than forward frequency sweeps that decrement mass. This result is accounted for by the asymmetry in ion energy absorption profiles as a function of AC frequency and the shift in ion secular frequency at higher amplitudes in the trap due to higher order fields. We also found that use of higher AC amplitudes in forward frequency sweeps biases ions toward ejection at points of higher order parametric resonance, despite using only dipolar excitation. Higher AC amplitudes also increase peak width and decrease sensitivity in both forward and reverse frequency sweeps. Higher sensitivity and resolution were obtained at higher trap pressures in the secular frequency scan, in contrast to conventional resonance ejection scans, which showed the opposite trend in resolution on the Mini 12. Mass range is shown to be naturally extended in secular frequency scanning when ejecting ions by sweeping the AC waveform through low frequencies, a method which is similar, but arguably superior, to the more usual method of mass range extension using low q resonance ejection. Graphical Abstract ᅟ.

Forward Modeling of Coronal Mass Ejection Flux Ropes in the Inner Heliosphere with 3DCORE.

PubMed

Möstl, C; Amerstorfer, T; Palmerio, E; Isavnin, A; Farrugia, C J; Lowder, C; Winslow, R M; Donnerer, J M; Kilpua, E K J; Boakes, P D

2018-03-01

Forecasting the geomagnetic effects of solar storms, known as coronal mass ejections (CMEs), is currently severely limited by our inability to predict the magnetic field configuration in the CME magnetic core and by observational effects of a single spacecraft trajectory through its 3-D structure. CME magnetic flux ropes can lead to continuous forcing of the energy input to the Earth's magnetosphere by strong and steady southward-pointing magnetic fields. Here we demonstrate in a proof-of-concept way a new approach to predict the southward field B z in a CME flux rope. It combines a novel semiempirical model of CME flux rope magnetic fields (Three-Dimensional Coronal ROpe Ejection) with solar observations and in situ magnetic field data from along the Sun-Earth line. These are provided here by the MESSENGER spacecraft for a CME event on 9-13 July 2013. Three-Dimensional Coronal ROpe Ejection is the first such model that contains the interplanetary propagation and evolution of a 3-D flux rope magnetic field, the observation by a synthetic spacecraft, and the prediction of an index of geomagnetic activity. A counterclockwise rotation of the left-handed erupting CME flux rope in the corona of 30° and a deflection angle of 20° is evident from comparison of solar and coronal observations. The calculated Dst matches reasonably the observed Dst minimum and its time evolution, but the results are highly sensitive to the CME axis orientation. We discuss assumptions and limitations of the method prototype and its potential for real time space weather forecasting and heliospheric data interpretation.

Forward Modeling of Coronal Mass Ejection Flux Ropes in the Inner Heliosphere with 3DCORE

NASA Astrophysics Data System (ADS)

Möstl, C.; Amerstorfer, T.; Palmerio, E.; Isavnin, A.; Farrugia, C. J.; Lowder, C.; Winslow, R. M.; Donnerer, J. M.; Kilpua, E. K. J.; Boakes, P. D.

2018-03-01

Forecasting the geomagnetic effects of solar storms, known as coronal mass ejections (CMEs), is currently severely limited by our inability to predict the magnetic field configuration in the CME magnetic core and by observational effects of a single spacecraft trajectory through its 3-D structure. CME magnetic flux ropes can lead to continuous forcing of the energy input to the Earth's magnetosphere by strong and steady southward-pointing magnetic fields. Here we demonstrate in a proof-of-concept way a new approach to predict the southward field Bz in a CME flux rope. It combines a novel semiempirical model of CME flux rope magnetic fields (Three-Dimensional Coronal ROpe Ejection) with solar observations and in situ magnetic field data from along the Sun-Earth line. These are provided here by the MESSENGER spacecraft for a CME event on 9-13 July 2013. Three-Dimensional Coronal ROpe Ejection is the first such model that contains the interplanetary propagation and evolution of a 3-D flux rope magnetic field, the observation by a synthetic spacecraft, and the prediction of an index of geomagnetic activity. A counterclockwise rotation of the left-handed erupting CME flux rope in the corona of 30° and a deflection angle of 20° is evident from comparison of solar and coronal observations. The calculated Dst matches reasonably the observed Dst minimum and its time evolution, but the results are highly sensitive to the CME axis orientation. We discuss assumptions and limitations of the method prototype and its potential for real time space weather forecasting and heliospheric data interpretation.

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

Genda, H.; Kobayashi, H.; Kokubo, E., E-mail: genda@elsi.jp

In our solar system, Mars-sized protoplanets frequently collided with each other during the last stage of terrestrial planet formation, called the giant impact stage. Giant impacts eject a large amount of material from the colliding protoplanets into the terrestrial planet region, which may form debris disks with observable infrared excesses. Indeed, tens of warm debris disks around young solar-type stars have been observed. Here we quantitatively estimate the total mass of ejected materials during the giant impact stages. We found that ∼0.4 times the Earth’s mass is ejected in total throughout the giant impact stage. Ejected materials are ground down bymore » collisional cascade until micron-sized grains are blown out by radiation pressure. The depletion timescale of these ejected materials is determined primarily by the mass of the largest body among them. We conducted high-resolution simulations of giant impacts to accurately obtain the mass of the largest ejected body. We then calculated the evolution of the debris disks produced by a series of giant impacts and depleted by collisional cascades to obtain the infrared excess evolution of the debris disks. We found that the infrared excess is almost always higher than the stellar infrared flux throughout the giant impact stage (∼100 Myr) and is sometimes ∼10 times higher immediately after a giant impact. Therefore, giant impact stages would explain the infrared excess from most observed warm debris disks. The observed fraction of stars with warm debris disks indicates that the formation probability of our solar-system-like terrestrial planets is approximately 10%.« less

Formation of a black hole in the dark.

PubMed

Mirabel, I Félix; Rodrigues, Irapuan

2003-05-16

We show that the black hole in the x-ray binary Cygnus X-1 was formed in situ and did not receive an energetic trigger from a nearby supernova. The progenitor of the black hole had an initial mass greater than 40 solar masses, and during the collapse to form the approximately 10-solar mass black hole of Cygnus X-1, the upper limit for the mass that could have been suddenly ejected is approximately 1 solar mass, much less than the mass ejected in a supernova. The observations suggest that high-mass stellar black holes may form promptly, when massive stars disappear silently.

In-depth study of in-trap high-resolution mass separation by transversal ion ejection from a multi-reflection time-of-flight device.

PubMed

Fischer, Paul; Knauer, Stefan; Marx, Gerrit; Schweikhard, Lutz

2018-01-01

The recently introduced method of ion separation by transversal ejection of unwanted species in electrostatic ion-beam traps and multi-reflection time-of-flight devices has been further studied in detail. As this separation is performed during the ion storage itself, there is no need for additional external devices such as ion gates or traps for either pre- or postselection of the ions of interest. The ejection of unwanted contaminant ions is performed by appropriate pulses of the potentials of deflector electrodes. These segmented ring electrodes are located off-center in the trap, i.e., between one of the two ion mirrors and the central drift tube, which also serves as a potential lift for capturing incoming ions and axially ejecting ions of interest after their selection. The various parameters affecting the selection effectivity and resolving power are illustrated with tin-cluster measurements, where isotopologue ion species provide mass differences down to a single atomic mass unit at ion masses of several hundred. Symmetric deflection voltages of only 10 V were found sufficient for the transversal ejection of ion species with as few as three deflection pulses. The duty cycle, i.e., the pulse duration with respect to the period of ion revolution, has been varied, resulting in resolving powers of up to several tens of thousands for this selection technique.

In-depth study of in-trap high-resolution mass separation by transversal ion ejection from a multi-reflection time-of-flight device

NASA Astrophysics Data System (ADS)

Fischer, Paul; Knauer, Stefan; Marx, Gerrit; Schweikhard, Lutz

2018-01-01

The recently introduced method of ion separation by transversal ejection of unwanted species in electrostatic ion-beam traps and multi-reflection time-of-flight devices has been further studied in detail. As this separation is performed during the ion storage itself, there is no need for additional external devices such as ion gates or traps for either pre- or postselection of the ions of interest. The ejection of unwanted contaminant ions is performed by appropriate pulses of the potentials of deflector electrodes. These segmented ring electrodes are located off-center in the trap, i.e., between one of the two ion mirrors and the central drift tube, which also serves as a potential lift for capturing incoming ions and axially ejecting ions of interest after their selection. The various parameters affecting the selection effectivity and resolving power are illustrated with tin-cluster measurements, where isotopologue ion species provide mass differences down to a single atomic mass unit at ion masses of several hundred. Symmetric deflection voltages of only 10 V were found sufficient for the transversal ejection of ion species with as few as three deflection pulses. The duty cycle, i.e., the pulse duration with respect to the period of ion revolution, has been varied, resulting in resolving powers of up to several tens of thousands for this selection technique.

Activity associated with the solar origin of coronal mass ejections

NASA Technical Reports Server (NTRS)

Webb, D. F.; Hundhausen, A. J.

1987-01-01

Solar coronal mass ejections (CMEs) observed in 1980 with the HAO Coronagraph/Polarimeter on the Solar Maximum Mission (SMM) satellite are compared with other forms of solar activity that might be physically related to the ejections. The solar phenomena checked and the method of association used were intentionally patterned after those of Munro et al.'s (1979) analysis of mass ejections observed with the Skylab coronagraph to facilitate comparison of the two epochs. Comparison of the results reveals that the types and degree of CME associations are similar near solar activity minimum and at maximum. For both epochs, most CMEs with associations had associated eruptive prominences, and the proportions of association of all types of activity were similar. A high percentage of association between SMM CMEs and X-ray long duration events is also found, in agreement with Skylab results. It is concluded that most CMEs are the result of the destabilization and eruption of a prominence and its overlying coronal structure, or of a magnetic structure capable of supporting a prominence.

Mass selectivity of dipolar resonant excitation in a linear quadrupole ion trap.

PubMed

Douglas, D J; Konenkov, N V

2014-03-15

For mass analysis, linear quadrupole ion traps operate with dipolar excitation of ions for either axial or radial ejection. There have been comparatively few computer simulations of this process. We introduce a new concept, the excitation contour, S(q), the fraction of the excited ions that reach the trap electrodes when trapped at q values near that corresponding to the excitation frequency. Ion trajectory calculations are used to calculate S(q). Ions are given Gaussian distributions of initial positions in x and y, and thermal initial velocity distributions. To model gas damping, a drag force is added to the equations of motion. The effects of the initial conditions, ejection Mathieu parameter q, scan speed, excitation voltage and collisional damping, are modeled. We find that, with no buffer gas, the mass resolution is mostly determined by the excitation time and is given by R~dβ/dq qn, where β(q) determines the oscillation frequency, and n is the number of cycles of the trapping radio frequency during the excitation or ejection time. The highest resolution at a given scan speed is reached with the lowest excitation amplitude that gives ejection. The addition of a buffer gas can increase the mass resolution. The simulation results are in broad agreement with experiments. The excitation contour, S(q), introduced here, is a useful tool for studying the ejection process. The excitation strength, excitation time and buffer gas pressure interact in a complex way but, when set properly, a mass resolution R0.5 of at least 10,000 can be obtained at a mass-to-charge ratio of 609. Copyright © 2014 John Wiley & Sons, Ltd.

Disruption of a helmet streamer by photospheric shear

NASA Technical Reports Server (NTRS)

Linker, Jon A.; Mikic, Zoran

1995-01-01

Helmet streamers on the Sun have been observed to be the site of coronal mass ejections, dynamic events that eject coronal plasma and magnetic fields into the solar wind. We develop a two-dimensional (azimuthally symmetric) helmet streamer configuration by computing solutions of the time-dependent magnetohydrodynamic (MHD) equations, and we investigate the evolution of the configuration when photospheric shearing motions are imposed. We find that the configuration disrupts when a critical shear is exceeded, ejecting a plasmoid into the solar wind. The results are similar to the case of a sheared dipole magnetic field in a hydrostatic atmosphere (Mikic & Linker 1994). However, the presence of the outflowing solar wind makes the disruption significantly more energetic when a helmet streamer is sheared. Our resutls suggest that shearing of helmet streamers may initiate coronal mass ejections.

Tin particle size measurements in high explosively driven shockwave experiments using Mie scattering method

NASA Astrophysics Data System (ADS)

Monfared, Shabnam; Buttler, William; Schauer, Martin; Lalone, Brandon; Pack, Cora; Stevens, Gerald; Stone, Joseph; Special Technologies Laboratory Collaboration; Los Alamos National Laboratory Team

2014-03-01

Los Alamos National Laboratory is actively engaged in the study of material failure physics to support the hydrodynamic models development, where an important failure mechanism of explosively shocked metals causes mass ejection from the backside of a shocked surface with surface perturbations. Ejecta models are in development for this situation. Our past work has clearly shown that the total ejected mass and mass-velocity distribution sensitively link to the wavelength and amplitude of these perturbations. While we have had success developing ejecta mass and mass-velocity models, we need to better understand the size and size-velocity distributions of the ejected mass. To support size measurements we have developed a dynamic Mie scattering diagnostic based on a CW laser that permits measurement of the forward attenuation cross-section combined with a dynamic mass-density and mass-velocity distribution, as well as a measurement of the forward scattering cross-section at 12 angles (5- 32.5 degrees) in increments of 2.5 degrees. We compare size distribution followed from Beers law with attenuation cross-section and mass measurement to the dynamic size distribution determined from scattering cross-section alone. We report results from our first quality experiments.

A Tool for Empirical Forecasting of Major Flares, Coronal Mass Ejections, and Solar Particle Events from a Proxy of Active-Region Free Magnetic Energy

NASA Technical Reports Server (NTRS)

Barghouty, A. F.; Falconer, D. A.; Adams, J. H., Jr.

2010-01-01

This presentation describes a new forecasting tool developed for and is currently being tested by NASA s Space Radiation Analysis Group (SRAG) at JSC, which is responsible for the monitoring and forecasting of radiation exposure levels of astronauts. The new software tool is designed for the empirical forecasting of M and X-class flares, coronal mass ejections, as well as solar energetic particle events. Its algorithm is based on an empirical relationship between the various types of events rates and a proxy of the active region s free magnetic energy, determined from a data set of approx.40,000 active-region magnetograms from approx.1,300 active regions observed by SOHO/MDI that have known histories of flare, coronal mass ejection, and solar energetic particle event production. The new tool automatically extracts each strong-field magnetic areas from an MDI full-disk magnetogram, identifies each as an NOAA active region, and measures a proxy of the active region s free magnetic energy from the extracted magnetogram. For each active region, the empirical relationship is then used to convert the free magnetic energy proxy into an expected event rate. The expected event rate in turn can be readily converted into the probability that the active region will produce such an event in a given forward time window. Descriptions of the datasets, algorithm, and software in addition to sample applications and a validation test are presented. Further development and transition of the new tool in anticipation of SDO/HMI is briefly discussed.

Observational Properties of Coronal Mass Ejections

DTIC Science & Technology

2006-01-01

speeds 2.5. Masses and Energies of CMEs exceeded 2000 km s-1; the fastest CME speed measured thus far was 2657 km s-1 on 4 November 2000. When compiled The...accelerated. The average deceleration of the fastest (> 900 km s-1) The CME kinetic energies can also be calculated from the CME group is -16 m s-2...OBSERVATIONAL PROPERTIES OF CORONAL MASS EJECTIONS 15 *"...... .. ’..’... ... ’...... kinetic energy is 2.4 x 1030 ergs (5.0 x 1029 ergs) [Vourlidas, 2004

Real-Time Analysis of Global Waves Accompanying Coronal Mass Ejections

DTIC Science & Technology

2016-06-30

within the community with regards to the physical properties of “EIT waves” and the nature of their relationship with Moreton–Ramsey waves. Whereas...interpretation, with the paper currently in review by Solar Physics (Long et al. 2016). Although this interpretation suggests a strong correlation...recently accepted for publication in Solar Physics by Francile et al. (2016). Examining the event from 06 December 2006 ensures that the algorithm

The Slow and Fast Solar Wind Boundary, Corotating Interaction Regions, and Coronal Mass Ejection observations with Solar Probe Plus and Solar Orbiter (Invited)

NASA Astrophysics Data System (ADS)

Velli, M. M.

2013-12-01

The Solar Probe Plus and Solar Orbiter missions have as part of their goals to understand the source regions of the solar wind and of the heliospheric magnetic field. In the heliosphere, the solar wind is made up of interacting fast and slow solar wind streams as well as a clearly intermittent source of flow and field, arising from coronal mass ejections (CMEs). In this presentation a summary of the questions associated with the distibution of wind speeds and magnetic fields in the inner heliosphere and their origin on the sun will be summarized. Where and how does the sharp gradient in speeds develop close to the Sun? Is the wind source for fast and slow the same, and is there a steady component or is its origin always intermittent in nature? Where does the heliospheric current sheet form and how stable is it close to the Sun? What is the distribution of CME origins and is there a continuum from large CMEs to small blobs of plasma? We will describe our current knowledge and discuss how SPP and SO will contribute to a more comprehensive understanding of the sources of the solar wind and magnetic fields in the heliosphere.

Coronal mass ejections and their sheath regions in interplanetary space

NASA Astrophysics Data System (ADS)

Kilpua, Emilia; Koskinen, Hannu E. J.; Pulkkinen, Tuija I.

2017-11-01

Interplanetary coronal mass ejections (ICMEs) are large-scale heliospheric transients that originate from the Sun. When an ICME is sufficiently faster than the preceding solar wind, a shock wave develops ahead of the ICME. The turbulent region between the shock and the ICME is called the sheath region. ICMEs and their sheaths and shocks are all interesting structures from the fundamental plasma physics viewpoint. They are also key drivers of space weather disturbances in the heliosphere and planetary environments. ICME-driven shock waves can accelerate charged particles to high energies. Sheaths and ICMEs drive practically all intense geospace storms at the Earth, and they can also affect dramatically the planetary radiation environments and atmospheres. This review focuses on the current understanding of observational signatures and properties of ICMEs and the associated sheath regions based on five decades of studies. In addition, we discuss modelling of ICMEs and many fundamental outstanding questions on their origin, evolution and effects, largely due to the limitations of single spacecraft observations of these macro-scale structures. We also present current understanding of space weather consequences of these large-scale solar wind structures, including effects at the other Solar System planets and exoplanets. We specially emphasize the different origin, properties and consequences of the sheaths and ICMEs.

A Framework for Finding and Interpreting Stellar CMEs

NASA Astrophysics Data System (ADS)

Osten, Rachel A.; Wolk, Scott J.

2017-10-01

The astrophysical study of mass loss, both steady-state and transient, on the cool half of the HR diagram has implications both for the star itself and the conditions created around the star that can be hospitable or inimical to supporting life. Stellar coronal mass ejections (CMEs) have not been conclusively detected, despite the ubiquity with which their radiative counterparts in an eruptive event (flares) have been. I will review some of the different observational methods which have been used and possibly could be used in the future in the stellar case, emphasizing some of the difficulties inherent in such attempts. I will provide a framework for interpreting potential transient stellar mass loss in light of the properties of flares known to occur on magnetically active stars. This uses a physically motivated way to connect the properties of flares and coronal mass ejections and provides a testable hypothesis for observing or constraining transient stellar mass loss. Finally I will describe recent results using observations at low radio frequencies to detect stellar coronal mass ejections, and give updates on prospects using future facilities to make headway in this important area.

SN 2009ip: CONSTRAINING THE LATEST EXPLOSION PROPERTIES BY ITS LATE-PHASE LIGHT CURVE

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

Moriya, Takashi J., E-mail: moriyatk@astro.uni-bonn.de

We constrain the explosion and circumstellar properties at the 2012b event of SN 2009ip based on its recently reported late-phase bolometric light curve. The explosion energy and ejected mass at the 2012b event are estimated as 0.01 M{sub ⊙} and 2 × 10{sup 49} erg, respectively. The circumstellar medium is assumed to have two components: an inner shell and an outer wind. The inner shell, which is likely created at the 2012a event, has a mass of 0.2 M{sub ⊙}. The outer wind is created by the wind mass loss before the 2012a mass ejection, and the progenitor is estimatedmore » to have had a mass-loss rate of about 0.1 M{sub ⊙} yr{sup −1} with a wind velocity of 550 km s{sup −1} before the 2012a event. The estimated explosion energy and ejected mass indicate that the 2012b event is not caused by a regular SN.« less

Mass resolution of linear quadrupole ion traps with round rods.

PubMed

Douglas, D J; Konenkov, N V

2014-11-15

Auxiliary dipole excitation is widely used to eject ions from linear radio-frequency quadrupole ion traps for mass analysis. Linear quadrupoles are often constructed with round rod electrodes. The higher multipoles introduced to the electric potential by round rods might be expected to change the ion ejection process. We have therefore investigated the optimum ratio of rod radius, r, to field radius, r0, for excitation and ejection of ions. Trajectory calculations are used to determine the excitation contour, S(q), the fraction of ions ejected when trapped at q values close to the ejection (or excitation) q. Initial conditions are randomly selected from Gaussian distributions of the x and y coordinates and a thermal distribution of velocities. The N = 6 (12 pole) and N = 10 (20 pole) multipoles are added to the quadrupole potential. Peak shapes and resolution were calculated for ratios r/r0 from 1.09 to 1.20 with an excitation time of 1000 cycles of the trapping radio-frequency. Ratios r/r0 in the range 1.140 to 1.160 give the highest resolution and peaks with little tailing. Ratios outside this range give lower resolution and peaks with tails on either the low-mass side or the high-mass side of the peaks. This contrasts with the optimum ratio of 1.126-1.130 for a quadrupole mass filter operated conventionally at the tip of the first stability region. With the optimum geometry the resolution is 2.7 times greater than with an ideal quadrupole field. Adding only a 2.0% hexapole field to a quadrupole field increases the resolution by a factor of 1.6 compared with an ideal quadrupole field. Addition of a 2.0% octopole lowers resolution and degrades peak shape. With the optimum value of r/r0 , the resolution increases with the ejection time (measured in cycles of the trapping rf, n) approximately as R0.5 = 6.64n, in contrast to a pure quadrupole field where R0.5 = 1.94n. Adding weak nonlinear fields to a quadrupole field can improve the resolution with mass-selective ejection of ions by up to a factor of 2.7. The optimum ratio r/r0 is 1.14 to 1.16, which differs from the optimum ratio for a mass filter of 1.128-1.130. Copyright © 2014 John Wiley & Sons, Ltd.

Solar Eruptions, CMEs and Space Weather

NASA Technical Reports Server (NTRS)

Gopalswamy, Nat

2011-01-01

Coronal mass ejections (CMEs) are large-scale magnetized plasma structures ejected from the Sun and propagate far into the interplanetary medium. CMEs represent energy output from the Sun in the form of magnetized plasma and electromagnetic radiation. The electromagnetic radiation suddenly increases the ionization content of the ionosphere, thus impacting communication and navigation systems. The plasma clouds can drive shocks that accelerate charged particles to very high energies in the interplanetary space, which pose radiation hazard to astronauts and space systems. The plasma clouds also arrive at Earth in about two days and impact Earth's magnetosphere, producing geomagnetic storms. The magnetic storms result in a number of effects including induced currents that can disrupt power grids, railroads, and underground pipelines. This lecture presents an overview of the origin, propagation, and geospace consequences of solar storms.

Laboratory unraveling of matter accretion in young stars

PubMed Central

Revet, Guilhem; Chen, Sophia N.; Bonito, Rosaria; Khiar, Benjamin; Filippov, Evgeny; Argiroffi, Costanza; Higginson, Drew P.; Orlando, Salvatore; Béard, Jérôme; Blecher, Marius; Borghesi, Marco; Burdonov, Konstantin; Khaghani, Dimitri; Naughton, Kealan; Pépin, Henri; Portugall, Oliver; Riquier, Raphael; Rodriguez, Rafael; Ryazantsev, Sergei N.; Yu. Skobelev, Igor; Soloviev, Alexander; Willi, Oswald; Pikuz, Sergey; Ciardi, Andrea; Fuchs, Julien

2017-01-01

Accretion dynamics in the formation of young stars is still a matter of debate because of limitations in observations and modeling. Through scaled laboratory experiments of collimated plasma accretion onto a solid in the presence of a magnetic field, we open a first window on this phenomenon by tracking, with spatial and temporal resolution, the dynamics of the system and simultaneously measuring multiband emissions. We observe in these experiments that matter, upon impact, is ejected laterally from the solid surface and then refocused by the magnetic field toward the incoming stream. This ejected matter forms a plasma shell that envelops the shocked core, reducing escaped x-ray emission. This finding demonstrates one possible structure reconciling current discrepancies between mass accretion rates derived from x-ray and optical observations, respectively. PMID:29109974

Laboratory unraveling of matter accretion in young stars

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

Revet, Guilhem; Chen, Sophia N.; Bonito, Rosaria

Accretion dynamics in the formation of young stars is still a matter of debate because of limitations in observations and modeling. Through scaled laboratory experiments of collimated plasma accretion onto a solid in the presence of a magnetic field, we open a first window on this phenomenon by tracking, with spatial and temporal resolution, the dynamics of the system and simultaneously measuring multiband emissions. Here, we observe in these experiments that matter, upon impact, is ejected laterally from the solid surface and then refocused by the magnetic field toward the incoming stream. This ejected matter forms a plasma shell thatmore » envelops the shocked core, reducing escaped x-ray emission. Our finding demonstrates one possible structure reconciling current discrepancies between mass accretion rates derived from x-ray and optical observations, respectively.« less

Laboratory unraveling of matter accretion in young stars

DOE PAGES

Revet, Guilhem; Chen, Sophia N.; Bonito, Rosaria; ...

2017-11-01

Accretion dynamics in the formation of young stars is still a matter of debate because of limitations in observations and modeling. Through scaled laboratory experiments of collimated plasma accretion onto a solid in the presence of a magnetic field, we open a first window on this phenomenon by tracking, with spatial and temporal resolution, the dynamics of the system and simultaneously measuring multiband emissions. Here, we observe in these experiments that matter, upon impact, is ejected laterally from the solid surface and then refocused by the magnetic field toward the incoming stream. This ejected matter forms a plasma shell thatmore » envelops the shocked core, reducing escaped x-ray emission. Our finding demonstrates one possible structure reconciling current discrepancies between mass accretion rates derived from x-ray and optical observations, respectively.« less

Laboratory unraveling of matter accretion in young stars.

PubMed

Revet, Guilhem; Chen, Sophia N; Bonito, Rosaria; Khiar, Benjamin; Filippov, Evgeny; Argiroffi, Costanza; Higginson, Drew P; Orlando, Salvatore; Béard, Jérôme; Blecher, Marius; Borghesi, Marco; Burdonov, Konstantin; Khaghani, Dimitri; Naughton, Kealan; Pépin, Henri; Portugall, Oliver; Riquier, Raphael; Rodriguez, Rafael; Ryazantsev, Sergei N; Yu Skobelev, Igor; Soloviev, Alexander; Willi, Oswald; Pikuz, Sergey; Ciardi, Andrea; Fuchs, Julien

2017-11-01

Accretion dynamics in the formation of young stars is still a matter of debate because of limitations in observations and modeling. Through scaled laboratory experiments of collimated plasma accretion onto a solid in the presence of a magnetic field, we open a first window on this phenomenon by tracking, with spatial and temporal resolution, the dynamics of the system and simultaneously measuring multiband emissions. We observe in these experiments that matter, upon impact, is ejected laterally from the solid surface and then refocused by the magnetic field toward the incoming stream. This ejected matter forms a plasma shell that envelops the shocked core, reducing escaped x-ray emission. This finding demonstrates one possible structure reconciling current discrepancies between mass accretion rates derived from x-ray and optical observations, respectively.

Forward Modeling of Coronal Mass Ejection Flux Ropes in the Inner Heliosphere with 3DCORE

PubMed Central

Amerstorfer, T.; Palmerio, E.; Isavnin, A.; Farrugia, C. J.; Lowder, C.; Winslow, R. M.; Donnerer, J. M.; Kilpua, E. K. J.; Boakes, P. D.

2018-01-01

Abstract Forecasting the geomagnetic effects of solar storms, known as coronal mass ejections (CMEs), is currently severely limited by our inability to predict the magnetic field configuration in the CME magnetic core and by observational effects of a single spacecraft trajectory through its 3‐D structure. CME magnetic flux ropes can lead to continuous forcing of the energy input to the Earth's magnetosphere by strong and steady southward‐pointing magnetic fields. Here we demonstrate in a proof‐of‐concept way a new approach to predict the southward field B z in a CME flux rope. It combines a novel semiempirical model of CME flux rope magnetic fields (Three‐Dimensional Coronal ROpe Ejection) with solar observations and in situ magnetic field data from along the Sun‐Earth line. These are provided here by the MESSENGER spacecraft for a CME event on 9–13 July 2013. Three‐Dimensional Coronal ROpe Ejection is the first such model that contains the interplanetary propagation and evolution of a 3‐D flux rope magnetic field, the observation by a synthetic spacecraft, and the prediction of an index of geomagnetic activity. A counterclockwise rotation of the left‐handed erupting CME flux rope in the corona of 30° and a deflection angle of 20° is evident from comparison of solar and coronal observations. The calculated Dst matches reasonably the observed Dst minimum and its time evolution, but the results are highly sensitive to the CME axis orientation. We discuss assumptions and limitations of the method prototype and its potential for real time space weather forecasting and heliospheric data interpretation. PMID:29780287

Effect of particle entrainment on the runout of pyroclastic density currents

NASA Astrophysics Data System (ADS)

Fauria, Kristen E.; Manga, Michael; Chamberlain, Michael

2016-09-01

Pyroclastic density currents (PDCs) can erode soil and bedrock, yet we currently lack a mechanistic understanding of particle entrainment that can be incorporated into models and used to understand how PDC bulking affects runout. Here we quantify how particle splash, the ejection of particles due to impact by a projectile, entrains particles into dilute PDCs. We use scaled laboratory experiments to measure the mass of sand ejected by impacts of pumice, wood, and nylon spheres. We then derive an expression for particle splash that we validate with our experimental results as well as results from seven other studies. We find that the number of ejected particles scales with the kinetic energy of the impactor and the depth of the crater generated by the impactor. Last, we use a one-dimensional model of a dilute, compressible density current—where runout distance is controlled by air entrainment and particle exchange with the substrate—to examine how particle entrainment by splash affects PDC density and runout. Splash-driven particle entrainment can increase the runout distance of dilute PDCs by an order of magnitude. Furthermore, the temperature of entrained particles greatly affects runout and PDCs that entrain ambient temperature particles runout farther than those that entrain hot particles. Particle entrainment by splash therefore not only increases the runout of dilute PDCs but demonstrates that the temperature and composition of the lower boundary have consequences for PDC density, temperature, runout, hazards and depositional record.

Coaxial ion trap mass spectrometer: concentric toroidal and quadrupolar trapping regions.

PubMed

Peng, Ying; Hansen, Brett J; Quist, Hannah; Zhang, Zhiping; Wang, Miao; Hawkins, Aaron R; Austin, Daniel E

2011-07-15

We present the design and results for a new radio-frequency ion trap mass analyzer, the coaxial ion trap, in which both toroidal and quadrupolar trapping regions are created simultaneously. The device is composed of two parallel ceramic plates, the facing surfaces of which are lithographically patterned with concentric metal rings and covered with a thin film of germanium. Experiments demonstrate that ions can be trapped in either region, transferred from the toroidal to the quadrupolar region, and mass-selectively ejected from the quadrupolar region to a detector. Ions trapped in the toroidal region can be transferred to the quadrupole region using an applied ac signal in the radial direction, although it appears that the mechanism of this transfer does not involve resonance with the ion secular frequency, and the process is not mass selective. Ions in the quadrupole trapping region are mass analyzed using dipole resonant ejection. Multiple transfer steps and mass analysis scans are possible on a single population of ions, as from a single ionization/trapping event. The device demonstrates better mass resolving power than the radially ejecting halo ion trap and better sensitivity than the planar quadrupole ion trap.

Predicting the hypervelocity star population in Gaia

NASA Astrophysics Data System (ADS)

Marchetti, T.; Contigiani, O.; Rossi, E. M.; Albert, J. G.; Brown, A. G. A.; Sesana, A.

2018-06-01

Hypervelocity stars (HVSs) are amongst the fastest objects in our Milky Way. These stars are predicted to come from the Galactic centre (GC) and travel along unbound orbits across the Galaxy. In the coming years, the ESA satellite Gaia will provide the most complete and accurate catalogue of the Milky Way, with full astrometric parameters for more than 1 billion stars. In this paper, we present the expected sample size and properties (mass, magnitude, spatial, velocity distributions) of HVSs in the Gaia stellar catalogue. We build three Gaia mock catalogues of HVSs anchored to current observations, exploring different ejection mechanisms and GC stellar population properties. In all cases, we predict hundreds to thousands of HVSs with precise proper motion measurements within a few tens of kpc from us. For stars with a relative error in total proper motion below 10 {per cent}, the mass range extends to ˜10 M⊙ but peaks at ˜1 M⊙. The majority of Gaia HVSs will therefore probe a different mass and distance range compared to the current non-Gaia sample. In addition, a subset of a few hundreds to a few thousands of HVSs with M ˜ 3 M⊙ will be bright enough to have a precise measurement of the three-dimensional velocity from Gaia alone. Finally, we show that Gaia will provide more precise proper motion measurements for the current sample of HVS candidates. This will help identifying their birthplace narrowing down their ejection location, and confirming or rejecting their nature as HVSs. Overall, our forecasts are extremely encouraging in terms of quantity and quality of HVS data that can be exploited to constrain both the Milky Way potential and the GC properties.

Interplanetary Coronal Mass Ejections During 1996 - 2007

NASA Technical Reports Server (NTRS)

Richardson, I. G.; Cane, H. V.

2007-01-01

Interplanetary coronal mass ejections, the interplanetary counterparts of coronal mass ejections at the Sun, are the major drivers of interplanetary shocks in the heliosphere, and are associated with modulations of the galactic cosmic ray intensity, both short term (Forbush decreases caused by the passage of the shock, post-shock sheath, and ICME), and possibly with longer term modulation. Using several in-situ signatures of ICMEs, including plasma temperature, and composition, magnetic fields, and cosmic ray modulations, made by near-Earth spacecraft, we have compiled a "comprehensive" list of ICMEs passing the Earth since 1996, encompassing solar cycle 23. We summarize the properties of these ICMEs, such as their occurrence rate, speeds and other parameters, the fraction of ICMEs that are classic magnetic clouds, and their association with solar energetic particle events, halo CMEs, interplanetary shocks, geomagnetic storms, shocks and cosmic ray decreases.

Earth rocks on Mars: Must planetary quarantine be rethought

NASA Technical Reports Server (NTRS)

Melosh, H. J.

1988-01-01

Recent geochemical, isotopic, and rare gas studies suggest that eight SNC meteorites originated on the planet Mars. Since Martian rocks are found on Earth, consideration is being given to finding Earth rocks on Mars. Detailed consideration of the mechanism by which these meteorites were lofted into space strongly suggest that the process of stress-wave spallation near a large impact with, perhaps, an assist from vapor plume expansion, is the fundamental process by which lightly-shocked rock debris is ejected into interplanetary space. The theory of spall ejection was used to examine the mass and velocity of material ejected from the near vicinity of an impact. It seems likely that the half-dozen largest impact events on Earth would have ejected considerable masses of near surface rocks into interplanetary space. No computations were performed to indicate how long Earth ejecta would take to reach Mars.

The Prospect for Detecting Stellar Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Osten, Rachel A.; Crosley, Michael Kevin

2018-06-01

The astrophysical study of mass loss, both steady-state and transient, on the cool half of the HR diagram has implications bothfor the star itself and the conditions created around the star that can be hospitable or inimical to supporting life. Recent results from exoplanet studies show that planets around M dwarfs are exceedingly common, which together with the commonality of M dwarfs in our galaxy make this the dominant mode of star and planet configurations. The closeness of the exoplanets to the parent M star motivate a comprehensive understanding of habitability for these systems. Radio observations provide the most clear signature of accelerated particles and shocks in stars arising as the result of MHD processes in the stellar outer atmosphere. Stellar coronal mass ejections have not been conclusively detected, despite the ubiquity with which their radiative counterparts in an eruptive event (stellar flares) have. I will review some of the different observational methods which have been used and possibly could be used in the future in the stellar case, emphasizing some of the difficulties inherent in such attempts. I will provide a framework for interpreting potential transient stellar mass loss in light of the properties of flares known to occur on magnetically active stars. This uses a physically motivated way to connect the properties of flares and coronal mass ejections and provides a testable hypothesis for observing or constraining transient stellar mass loss. I will describe recent results using radio observations to detect stellar coronal mass ejections, and what those results imply about transient stellar mass loss. I will provide some motivation for what could be learned in this topic from space-based low frequency radio experiments.

Atmospheric Effects on Cosmic Ray Air Showers Observed with HAWC

NASA Astrophysics Data System (ADS)

Young, Steven

2014-01-01

The High Altitude Water Cherenkov Gamma Ray detector (HAWC), currently under construction on the Sierra Negra volcano near Puebla, Mexico, can be used to study solar physics with its scaler data acquisition system. Increases in the scaler rates are used to observe GeV cosmic rays from solar flares while decreases in the rates show the heliospheric disturbances associated with coronal mass ejections. However, weather conditions and height-dependent state variables such as pressure and temperature affect the production of extensive particle air showers that can be detected by the scaler system. To see if these atmospheric effects can be removed, we obtained local weather data from the Global Data Assimilation System (GDAS) and the local weather station at HAWC. The scaler pulse rates were then correlated to the pressure and temperature. We present data from a Forbush decrease observed by HAWC following a significant coronal mass ejection in April 2013, and describe our efforts to remove atmospheric variations from the scaler counts. This work was partially supported by the National Science Foundation’s REU program through NSF Award AST-1004881 to the University of Wisconsin-Madison.

Automated detection of solar eruptions

NASA Astrophysics Data System (ADS)

Hurlburt, N.

2015-12-01

Observation of the solar atmosphere reveals a wide range of motions, from small scale jets and spicules to global-scale coronal mass ejections (CMEs). Identifying and characterizing these motions are essential to advancing our understanding of the drivers of space weather. Both automated and visual identifications are currently used in identifying Coronal Mass Ejections. To date, eruptions near the solar surface, which may be precursors to CMEs, have been identified primarily by visual inspection. Here we report on Eruption Patrol (EP): a software module that is designed to automatically identify eruptions from data collected by the Atmospheric Imaging Assembly on the Solar Dynamics Observatory (SDO/AIA). We describe the method underlying the module and compare its results to previous identifications found in the Heliophysics Event Knowledgebase. EP identifies eruptions events that are consistent with those found by human annotations, but in a significantly more consistent and quantitative manner. Eruptions are found to be distributed within 15 Mm of the solar surface. They possess peak speeds ranging from 4 to 100 km/s and display a power-law probability distribution over that range. These characteristics are consistent with previous observations of prominences.

EVIDENCE FOR MASS EJECTION ASSOCIATED WITH LONG SECONDARY PERIODS IN RED GIANTS

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

Wood, P. R.; Nicholls, C. P., E-mail: wood@mso.anu.edu.a, E-mail: nicholls@mso.anu.edu.a

2009-12-10

Approximately 30% of luminous red giants exhibit a long secondary period (LSP) of variation in their light curves in addition to a shorter primary period of oscillation. The cause of the LSP has so far defied explanation: leading possibilities are binarity and a nonradial mode of oscillation. Here, large samples of red giants in the Large Magellanic Cloud both with and without LSPs are examined for evidence of an 8 or 24 mum mid-IR excess caused by circumstellar dust. It is found that stars with LSPs show a significant mid-IR excess compared to stars without LSPs. Furthermore, the near-IR Jmore » - K color seems unaffected by the presence of the 24 mum excess. These findings indicate that LSPs cause mass ejection from red giants and that the lost mass and circumstellar dust is most likely in either a clumpy or a disk-like configuration. The underlying cause of the LSP and the mass ejection remains unknown.« less

Stellar Wind Retention and Expulsion in Massive Star Clusters

NASA Astrophysics Data System (ADS)

Naiman, J. P.; Ramirez-Ruiz, E.; Lin, D. N. C.

2018-05-01

Mass and energy injection throughout the lifetime of a star cluster contributes to the gas reservoir available for subsequent episodes of star formation and the feedback energy budget responsible for ejecting material from the cluster. In addition, mass processed in stellar interiors and ejected as winds has the potential to augment the abundance ratios of currently forming stars, or stars which form at a later time from a retained gas reservoir. Here we present hydrodynamical simulations that explore a wide range of cluster masses, compactnesses, metallicities and stellar population age combinations in order to determine the range of parameter space conducive to stellar wind retention or wind powered gas expulsion in star clusters. We discuss the effects of the stellar wind prescription on retention and expulsion effectiveness, using MESA stellar evolutionary models as a test bed for exploring how the amounts of wind retention/expulsion depend upon the amount of mixing between the winds from stars of different masses and ages. We conclude by summarizing some implications for gas retention and expulsion in a variety of compact (σv ≳ 20 kms-1) star clusters including young massive star clusters (105 ≲ M/M⊙ ≲ 107, age ≲ 500 Myrs), intermediate age clusters (105 ≲ M/M⊙ ≲ 107, age ≈ 1 - 4 Gyrs), and globular clusters (105 ≲ M/M⊙ ≲ 107, age ≳ 10 Gyrs).

Imaging Coronal Mass Ejections and Large-Scale Solar Wind Structure Using IPS and Thomson-Scattered Sunlight (Invited)

NASA Astrophysics Data System (ADS)

Clover, J. M.; Jackson, B. V.; Buffington, A.; Hick, P. P.; Bisi, M. M.; Tokumaru, M.; Fujiki, K.

2010-12-01

The Solar Mass Ejection Imager (SMEI) observes Thomson-scattered white light from heliospheric electrons across almost all of the sky nearly all of the time since early 2003. Interplanetary scintillation (IPS) observations of velocity and g-level provide similar structure information but with a less-complete sky-and-time coverage. The Solar TErrestrial RElations Observatory (STEREO) twin spacecraft outer Heliospheric Imagers (HI-2) currently image the heliosphere in Thomson-scattered light near the ecliptic plane far from Earth. The Solar-Terrestrial Environment Laboratory (STELab) IPS observations provide IPS velocity and g-level values, which in conjunction with our tomographic reconstruction program, yield velocities and densities of the inner heliosphere in three dimensions. The same tomographic program substitutes SMEI Thomson-scattering brightness information for the g-level values to derive heliospheric densities from these data alone. We look at the global structure of the heliosphere concentrating mainly on three events from 2007 through the rise phase of Solar Cycle 24. The first event, observed in both the IPS and SMEI defines the three-dimensional velocity and density structure around the time of the shock observed at Earth on 02:02 UT 17 December 2007. The second event, seen only by SMEI, is that of the 23-26 April 2008 coronal mass ejection (CME) and its interplanetary counterpart. The third event is the CME (and its interplanetary counterpart) that took place 17 January 2010 and arrived at STEREO-B about four days later. For each event, we isolate the particular portion of the heliosphere attributed to the transient density structure using our tomographic technique, and then estimate its extent.

Tumor necrosis factor and interleukin-6 levels in hypertensive patients with and without left ventricular hypertrophy.

PubMed

Leibowitz, David; Planer, David; Ben-Ivgi, Fanny; Weiss, A Teddy; Bursztyn, Michael

2005-01-01

The objective of this prospective study was to examine the association between serum levels of TNF (tumor-necrosis factor) and IL-6 (interleukin-6) and left ventricular mass in hypertensive patients. Hypertensive patients currently receiving medical therapy were eligible. All subjects underwent echocardiography with measurements of left ventricular (LV) mass and ejection fraction (EF) and had serum levels of TNF and IL-6 measured by ELISA immunoassay. 35 subjects (20F, 15M; mean age 56.4 +/- 10.5 yrs) were studied. 19 patients (54%) had elevated LV mass. Of these patients, 6 (32%) had detectable serum TNF levels and 1 (7%) had detectable IL-6 levels, (p = NS). Hypertensive patients with elevated LV mass do not consistently exhibit elevated cytokine levels when compared to those with normal LV mass.

Direct observations of a flare related coronal and solar wind disturbance

NASA Technical Reports Server (NTRS)

Gosling, J. T.; Hildner, E.; Macqueen, R. M.; Munro, R. H.; Poland, A. I.; Ross, C. L.

1975-01-01

Numerous mass ejections from the sun have been detected with orbiting coronagraphs. Here for the first time we document and discuss the direct association of a coronagraph observed mass ejection, which followed a 2B flare, with a large interplanetary shock wave disturbance observed at 1 AU. Estimates of the mass and energy content of the coronal disturbance are in reasonably good agreement with estimates of the mass and energy content of the solar wind disturbance at 1 AU. The energy estimates as well as the transit time of the disturbance are also in good agreement with numerical models of shock wave propagation in the solar wind.

Low speed vehicle passenger ejection restraint effectiveness.

PubMed

Seluga, Kristopher J; Ojalvo, Irving U; Obert, Richard M

2005-07-01

Current golf carts and LSV's (Low Speed Vehicles) produce a significant number of passenger ejections during sharp turns. These LSV's do not typically possess seatbelts, but do provide outboard bench seat hip restraints that also serve as handholds. However, many current restraint designs appear incapable of preventing passenger ejections due to their low height and inefficient handhold position. Alternative handhold and hip restraint designs may improve passenger safety. Accordingly, this paper examines minimum size requirements for hip restraints to prevent passenger ejection during sharp turns and evaluates the effectiveness of a handhold mounted at the center of the bench seat. In this study, a simulation of a turning cart supplies the dynamic input to a biomechanical model of an adult male seated in a golf cart. Various restraint combinations are considered, both with and without the central handhold, to determine the likelihood of passenger ejection. It is shown that only the largest restraint geometries prevent passenger ejection. Adequate hip restraints should be much larger than current designs and a central handhold should be provided. In this way, golf cart and LSV manufacturers could reduce passenger ejections and improve fleet safety by incorporating recommendations provided herein.

REDEFINING THE BOUNDARIES OF INTERPLANETARY CORONAL MASS EJECTIONS FROM OBSERVATIONS AT THE ECLIPTIC PLANE

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

Cid, C.; Palacios, J.; Saiz, E.

2016-09-01

On 2015 January 6–7, an interplanetary coronal mass ejection (ICME) was observed at L1. This event, which can be associated with a weak and slow coronal mass ejection, allows us to discuss the differences between the boundaries of the magnetic cloud and the compositional boundaries. A fast stream from a solar coronal hole surrounding this ICME offers a unique opportunity to check the boundaries’ process definition and to explain differences between them. Using Wind and ACE data, we perform a complementary analysis involving compositional, magnetic, and kinematic observations providing relevant information regarding the evolution of the ICME as travelling awaymore » from the Sun. We propose erosion, at least at the front boundary of the ICME, as the main reason for the difference between the boundaries, and compositional signatures as the most precise diagnostic tool for the boundaries of ICMEs.« less

Focused transport of energetic particles along magnetic field lines draped around a coronal mass ejection

NASA Technical Reports Server (NTRS)

Tan, L. C.; Mason, G. M.; Lee, M. A.; Klecker, B.; Ipavich, F. M.

1992-01-01

Evidence is presented for focused transport of energetic particles along magnetic field lines draped around a coronal mass ejection. This evidence was obtained with the University of Maryland/Max-Planck-Institute experiment on the ISEE-3 spacecraft during the decay phase of the June 6, 1979, solar particle event. During the early portion of the decay phase of this event, interplanetary magnetic field lines were apparently draped around a coronal mass ejection, leading to a small focusing length on the western flank where ISEE 3 was located. A period of very slow decrease of particle intensity was observed, along with large sunward anisotropy in the solar wind frame, which is inconsistent with predictions of the standard Fokker-Planck equation models for diffusive transport. It was found possible to fit the observations, assuming that focused transport dominates and that the particle pitch angle scattering is isotropic.

Treatment of Viscosity in the Shock Waves Observed After Two Consecutive Coronal Mass Ejection Activities CME08/03/2012 and CME15/03/2012

NASA Astrophysics Data System (ADS)

Cavus, Huseyin

2016-11-01

A coronal mass ejection (CME) is one of the most the powerful activities of the Sun. There is a possibility to produce shocks in the interplanetary medium after CMEs. Shock waves can be observed when the solar wind changes its velocity from being supersonic nature to being subsonic nature. The investigations of such activities have a central place in space weather purposes, since; the interaction of shocks with viscosity is one of the most important problems in the supersonic and compressible gas flow regime (Blazek in Computational fluid dynamics: principles and applications. Elsevier, Amsterdam 2001). The main aim of present work is to achieve a search for the viscosity effects in the shocks occurred after two consecutive coronal mass ejection activities in 2012 (i.e. CME08/03/2012 and CME15/03/2012).

Evaluation of high field and/or local heating based material degradation of nanoscale metal emitter tips: a molecular dynamics analysis

NASA Astrophysics Data System (ADS)

Zhang, Z.; Giesselmann, M.; Mankowski, J.; Dickens, J.; Neuber, A.; Joshi, R. P.

2017-05-01

A molecular dynamics (MD) model is used to study the potential for mass ejection from a metal nanoprotrusion, driven by high fields and temperature increases. Three-dimensional calculations of the electric fields surrounding the metal emitter are used to obtain the Maxwell stress on the metal. This surface loading is coupled into MD simulations. Our results show that mass ejection from the nanotip is possible and indicate that both larger aspect ratios and higher local temperatures will drive the instability. Hence it is predicted that in a nonuniform distribution of emitters, the longer and thinner sites will suffer the most damage, which is generally in keeping with the trends of a recent experimental report (Parson et al 2014 IEEE Trans. Plasma Sci. 42 3982). A possible hypothesis for mass ejection in the absence of a distinct nanoprotrusion is also discussed.

Features of solar wind streams on June 21-28, 2015 as a result of interactions between coronal mass ejections and recurrent streams from coronal holes

NASA Astrophysics Data System (ADS)

Shugay, Yu. S.; Slemzin, V. A.; Rod'kin, D. G.

2017-11-01

Coronal sources and parameters of solar wind streams during a strong and prolonged geomagnetic disturbance in June 2015 have been considered. Correspondence between coronal sources and solar wind streams at 1 AU has been determined using an analysis of solar images, catalogs of flares and coronal mass ejections, solar wind parameters including the ionic composition. The sources of disturbances in the considered period were a sequence of five coronal mass ejections that propagated along the recurrent solar wind streams from coronal holes. The observed differences from typical in magnetic and kinetic parameters of solar wind streams have been associated with the interactions of different types of solar wind. The ionic composition has proved to be a good additional marker for highlighting components in a mixture of solar wind streams, which can be associated with different coronal sources.

Understanding the Global Structure and Evolution of Coronal Mass Ejections in the Solar Wind

NASA Technical Reports Server (NTRS)

Riley, Pete

2004-01-01

This report summarizes the technical progress made during the first six months of the second year of the NASA Living with a Star program contract Understanding the global structure and evolution of coronal mass ejections in the solar wind, between NASA and Science Applications International Corporation, and covers the period November 18, 2003 - May 17,2004. Under this contract SAIC has conducted numerical and data analysis related to fundamental issues concerning the origin, intrinsic properties, global structure, and evolution of coronal mass ejections in the solar wind. During this working period we have focused on a quantitative assessment of 5 flux rope fitting techniques. In the following sections we summarize the main aspects of this work and our proposed investigation plan for the next reporting period. Thus far, our investigation has resulted in 6 refereed scientific publications and we have presented the results at a number of scientific meetings and workshops.

Physical properties of erupting plasma associated with coronal mass ejections

NASA Astrophysics Data System (ADS)

Lee, J.; Raymond, J. C.; Reeves, K. K.; Moon, Y.; Kim, K.

2013-12-01

We investigate the physical properties (temperature, density, and mass) of erupting plasma observed in X-rays and EUV, which are all associated with coronal mass ejections observed by SOHO/LASCO. The erupting plasmas are observed as absorption or emission features in the low corona. The absorption feature provides a lower limit to the cold mass while the emission feature provides an upper limit to the mass of observed plasma in X-ray and EUV. We compare the mass constraints for each temperature response and find that the mass estimates in EUV and XRT are smaller than the total mass in the coronagraph. Several events were observed by a few passbands in the X-rays, which allows us to determine the temperature of the eruptive plasma using a filter ratio method. The temperature of one event is estimated at about 8.6 MK near the top of the erupting plasma. This measurement is possibly an average temperature for higher temperature plasma because the XRT is more sensitive at higher temperatures. In addition, a few events show that the absorption features of a prominence or a loop change to emission features with the beginning of their eruptions in all EUV wavelengths of SDO/AIA, which indicates the heating of the plasma. By estimating the physical properties of the erupting plasmas, we discuss the heating of the plasmas associated with coronal mass ejections in the low corona.

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

Jewitt, David, E-mail: jewitt@ucla.edu; Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1567

Some asteroids eject dust, unexpectedly producing transient, comet-like comae and tails. First ascribed to the sublimation of near-surface water ice, mass-losing asteroids (also called 'main-belt comets') can in fact be driven by a surprising diversity of mechanisms. In this paper, we consider 11 dynamical asteroids losing mass, in nine of which the ejected material is spatially resolved. We address mechanisms for producing mass loss including rotational instability, impact ejection, electrostatic repulsion, radiation pressure sweeping, dehydration stresses, and thermal fracture, in addition to the sublimation of ice. In two objects (133P and 238P) the repetitive nature of the observed activity leavesmore » ice sublimation as the only reasonable explanation, while in a third ((596) Scheila), a recent impact is the cause. Another impact may account for activity in P/2010 A2, but this tiny object can also be explained as having shed mass after reaching rotational instability. Mass loss from (3200) Phaethon is probably due to cracking or dehydration at extreme ({approx}1000 K) perihelion temperatures, perhaps aided by radiation pressure sweeping. For the other bodies, the mass-loss mechanisms remain unidentified, pending the acquisition of more and better data. While the active asteroid sample size remains small, the evidence for an astonishing diversity of mass-loss processes in these bodies is clear.« less

Quasi-periodic Oscillations in Flares and Coronal Mass Ejections Associated with Magnetic Reconnection

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

Takahashi, Takuya; Shibata, Kazunari; Qiu, Jiong, E-mail: takahasi@kusastro.kyoto-u.ac.jp

We propose a mechanism for quasi-periodic oscillations of both coronal mass ejections (CMEs) and flare loops as related to magnetic reconnection in eruptive solar flares. We perform two-dimensional numerical MHD simulations of magnetic flux rope eruption, with three different values of the global Lundquist number. In the low Lundquist number run, no oscillatory behavior is found. In the moderate Lundquist number run, on the other hand, quasi-periodic oscillations are excited both at the bottom of the flux rope and at the flare loop top. In the high Lundquist number run, quasi-periodic oscillations are also excited; in the meanwhile, the dynamicsmore » become turbulent owing to the formation of multiple plasmoids in the reconnection current sheet. In high and moderate Lundquist number runs, thin reconnection jets collide with the flux rope bottom or flare loop top and dig them deeply. Steep oblique shocks are formed as termination shocks where reconnection jets are bent (rather than decelerated) in the horizontal direction, resulting in supersonic backflows. The structure becomes unstable, and quasi-periodic oscillations of supersonic backflows appear at locally confined high-beta regions at both the flux rope bottom and flare loop top. We compare the observational characteristics of quasi-periodic oscillations in erupting flux ropes, post-CME current sheets, flare ribbons, and light curves with corresponding dynamical structures found in our simulation.« less

Quasi-periodic Oscillations in Flares and Coronal Mass Ejections Associated with Magnetic Reconnection

NASA Astrophysics Data System (ADS)

Takahashi, Takuya; Qiu, Jiong; Shibata, Kazunari

2017-10-01

We propose a mechanism for quasi-periodic oscillations of both coronal mass ejections (CMEs) and flare loops as related to magnetic reconnection in eruptive solar flares. We perform two-dimensional numerical MHD simulations of magnetic flux rope eruption, with three different values of the global Lundquist number. In the low Lundquist number run, no oscillatory behavior is found. In the moderate Lundquist number run, on the other hand, quasi-periodic oscillations are excited both at the bottom of the flux rope and at the flare loop top. In the high Lundquist number run, quasi-periodic oscillations are also excited; in the meanwhile, the dynamics become turbulent owing to the formation of multiple plasmoids in the reconnection current sheet. In high and moderate Lundquist number runs, thin reconnection jets collide with the flux rope bottom or flare loop top and dig them deeply. Steep oblique shocks are formed as termination shocks where reconnection jets are bent (rather than decelerated) in the horizontal direction, resulting in supersonic backflows. The structure becomes unstable, and quasi-periodic oscillations of supersonic backflows appear at locally confined high-beta regions at both the flux rope bottom and flare loop top. We compare the observational characteristics of quasi-periodic oscillations in erupting flux ropes, post-CME current sheets, flare ribbons, and light curves with corresponding dynamical structures found in our simulation.

Development of a current sheet in the wake of a fast coronal mass ejection

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

Ling, A. G.; Webb, D. F.; Burkepile, J. T.

2014-04-01

A bright ray that developed in the wake of a fast coronal mass ejection (CME) on 2005 September 7 presents a unique opportunity to study the early development and physical characteristics of a reconnecting current sheet (CS). Polarization brightness images from the Mk4 K-Coronameter at the Mauna Loa Solar Observatory are used to determine the structure of the ray along its axis low in the corona as it progressed outward. Coverage of the early development of the ray out to ∼1.3 R {sub ☉} for a period of ∼27 hr after the start of the event enables for the firstmore » time in white light a measurement of a CME CS from the top of the arcade to the base of the flux rope. Measured widths of the ray are combined to obtain the kinematics of the upper and lower {sup Y-}points described in reconnection flux-rope models such as that of Lin and Forbes. The time dependence of these points are used to derive values for the speed and acceleration of the growth of the CS. We note the appearance of a large structure which increases in size as it expands outward in the early development of the ray and an apparent oscillation with a period of ∼0.5 hr in the position angle of the ray.« less

Magnetohydrodynamic simulations of the ejection of a magnetic flux rope

NASA Astrophysics Data System (ADS)

Pagano, P.; Mackay, D. H.; Poedts, S.

2013-06-01

Context. Coronal mass ejections (CME's) are one of the most violent phenomena found on the Sun. One model to explain their occurrence is the flux rope ejection model. In this model, magnetic flux ropes form slowly over time periods of days to weeks. They then lose equilibrium and are ejected from the solar corona over a few hours. The contrasting time scales of formation and ejection pose a serious problem for numerical simulations. Aims: We simulate the whole life span of a flux rope from slow formation to rapid ejection and investigate whether magnetic flux ropes formed from a continuous magnetic field distribution, during a quasi-static evolution, can erupt to produce a CME. Methods: To model the full life span of magnetic flux ropes we couple two models. The global non-linear force-free field (GNLFFF) evolution model is used to follow the quasi-static formation of a flux rope. The MHD code ARMVAC is used to simulate the production of a CME through the loss of equilibrium and ejection of this flux rope. Results: We show that the two distinct models may be successfully coupled and that the flux rope is ejected out of our simulation box, where the outer boundary is placed at 2.5 R⊙. The plasma expelled during the flux rope ejection travels outward at a speed of 100 km s-1, which is consistent with the observed speed of CMEs in the low corona. Conclusions: Our work shows that flux ropes formed in the GNLFFF can lead to the ejection of a mass loaded magnetic flux rope in full MHD simulations. Coupling the two distinct models opens up a new avenue of research to investigate phenomena where different phases of their evolution occur on drastically different time scales. Movies are available in electronic form at http://www.aanda.org

Determining the full halo coronal mass ejection characteristics

NASA Astrophysics Data System (ADS)

Fainshtein, V. G.

2009-03-01

In this paper we determined the parameters of 45 full halo coronal mass ejections (HCMEs) for various modifications of their cone forms (“ice cream cone models”). We show that the CME determined characteristics depend significantly on the CME chosen form. We show that, regardless of the CME chosen form, the trajectory of practically all the considered HCMEs deviate from the radial direction to the Sun-to-Earth axis at the initial stage of their movement.

Small Flare and a Coronal Mass Ejection

NASA Image and Video Library

2018-01-31

The sun shot out a small coronal mass ejection that was also associated with a small flare (Jan. 22, 2018). The video, which covers about 5 hours, shows the burst of plasma as the magnetic loops break apart. Immediately the magnetic fields brighten intensely and begin to reorganize themselves in coils above the active region. The images were taken in a wavelength of extreme ultraviolet light. Videos are available at https://photojournal.jpl.nasa.gov/catalog/PIA22184

MHD shocks in coronal mass ejections

NASA Technical Reports Server (NTRS)

Steinolfson, R. S.

1991-01-01

The primary objective of this research program is the study of the magnetohydrodynamic (MHD) shocks and nonlinear simple waves produced as a result of the interaction of ejected lower coronal plasma with the ambient corona. The types of shocks and nonlinear simple waves produced for representative coronal conditions and disturbance velocities were determined. The wave system and the interactions between the ejecta and ambient corona were studied using both analytic theory and numerical solutions of the time-dependent, nonlinear MHD equations. Observations from the SMM coronagraph/polarimeter provided both guidance and motivation and are used extensively in evaluating the results. As a natural consequence of the comparisons with the data, the simulations assisted in better understanding the physical interactions in coronal mass ejections (CME's).

Partial analysis of the flare-prominence of 30 April 1974

NASA Technical Reports Server (NTRS)

Wu, S. T.; Dryer, M.; Mcintosh, P. S.; Reichmann, E.

1975-01-01

A portion of an east limb flare-prominence observed in H-alpha light is analyzed. Following rapid achievement of a maximum mass-ejection velocity of about 375 km/s, the ascending prominence reached a height of at least 200,000 km. A one-dimensional time-dependent hydrodynamic theory is used to compute the total mass and energy ejected during this part of the event. Theoretical aspects of the coronal response are discussed. It is concluded that a moderate temperature and density pulse (factors of ten and two, respectively) for a duration of only 3 min is sufficient for an acceptable simulation of the H-alpha observations and the likely coronal response to the ascending prominence and flare-related ejections.

Long-term echocardiographic and cardioscintigraphic effects of growth hormone treatment in adults with Prader-Willi syndrome.

PubMed

Marzullo, Paolo; Marcassa, Claudio; Minocci, Alessandro; Campini, Riccardo; Eleuteri, Ermanno; Gondoni, Luca Alessandro; Aimaretti, Gianluca; Sartorio, Alessandro; Scacchi, Massimo; Grugni, Graziano

2015-05-01

In Prader-Willi syndrome (PWS), an altered GH secretion has been related to reduced cardiac mass and systolic function compared to controls. The objective was to evaluate the cardiovascular response to a 4-year GH therapy in adult PWS patients. Study participants were nine severely obese PWS adults (three females, six males) and 13 age-, gender-, and body mass index-matched obese controls. In an open-label prospective study, assessment of endocrine parameters and metabolic outcome, whole-body and abdominal fat scans, echocardiography, and radionuclide angiography in unstimulated and dobutamine-stimulated conditions were conducted at baseline and after 1 and 4 years of GH treatment. GH treatment increased IGF-1 (P < .0001), decreased C-reactive protein levels (P < .05), improved visceral fat mass (P < .05), and achieved near-significant changes of fat and fat-free body mass in PWS patients. Left ventricle mass indexed by fat mass increased significantly after 1 and 4 years of GH therapy (P < .05) without evident abnormalities of diastolic function, while a trend toward a reduction of the ejection fraction was documented by echocardiography (P = .054). Radionuclide angiography revealed stable values throughout the study of both the left and right ventricle ejection fractions, although this was accompanied by a statistically nonsignificant reduction of the left ventricle filling rate. A positive association between lean body mass and left ventricle ejection fraction was evident during the study (P < .05). GH therapy increased the cardiac mass of PWS adults without causing overt abnormalities of systolic and diastolic function. Although the association between lean mass and left ventricle ejection fraction during GH therapy corroborates a favorable systemic outcome of long-term GH treatment in adults with PWS, subtle longitudinal modifications of functional parameters advocate appropriate cardiac monitoring in the long-term therapeutic strategy for PWS.

Hydrocode modeling of the spallation process during hypervelocity impacts: Implications for the ejection of Martian meteorites

NASA Astrophysics Data System (ADS)

Kurosawa, Kosuke; Okamoto, Takaya; Genda, Hidenori

2018-02-01

Hypervelocity ejection of material by impact spallation is considered a plausible mechanism for material exchange between two planetary bodies. We have modeled the spallation process during vertical impacts over a range of impact velocities from 6 to 21 km/s using both grid- and particle-based hydrocode models. The Tillotson equations of state, which are able to treat the nonlinear dependence of density on pressure and thermal pressure in strongly shocked matter, were used to study the hydrodynamic-thermodynamic response after impacts. The effects of material strength and gravitational acceleration were not considered. A two-dimensional time-dependent pressure field within a 1.5-fold projectile radius from the impact point was investigated in cylindrical coordinates to address the generation of spalled material. A resolution test was also performed to reject ejected materials with peak pressures that were too low due to artificial viscosity. The relationship between ejection velocity veject and peak pressure Ppeak was also derived. Our approach shows that "late-stage acceleration" in an ejecta curtain occurs due to the compressible nature of the ejecta, resulting in an ejection velocity that can be higher than the ideal maximum of the resultant particle velocity after passage of a shock wave. We also calculate the ejecta mass that can escape from a planet like Mars (i.e., veject > 5 km/s) that matches the petrographic constraints from Martian meteorites, and which occurs when Ppeak = 30-50 GPa. Although the mass of such ejecta is limited to 0.1-1 wt% of the projectile mass in vertical impacts, this is sufficient for spallation to have been a plausible mechanism for the ejection of Martian meteorites. Finally, we propose that impact spallation is a plausible mechanism for the generation of tektites.

The dynamic ejecta of compact object mergers and eccentric collisions.

PubMed

Rosswog, Stephan

2013-06-13

Compact object mergers eject neutron-rich matter in a number of ways: by the dynamical ejection mediated by gravitational torques, as neutrino-driven winds, and probably also a good fraction of the resulting accretion disc finally becomes unbound by a combination of viscous and nuclear processes. If compact binary mergers indeed produce gamma-ray bursts, there should also be an interaction region where an ultra-relativistic outflow interacts with the neutrino-driven wind and produces moderately relativistic ejecta. Each type of ejecta has different physical properties, and therefore plays a different role for nucleosynthesis and for the electromagnetic (EM) transients that go along with compact object encounters. Here, we focus on the dynamic ejecta and present results for over 30 hydrodynamical simulations of both gravitational wave-driven mergers and parabolic encounters as they may occur in globular clusters. We find that mergers eject approximately 1 per cent of a Solar mass of extremely neutron-rich material. The exact amount, as well as the ejection velocity, depends on the involved masses with asymmetric systems ejecting more material at higher velocities. This material undergoes a robust r-process and both ejecta amount and abundance pattern are consistent with neutron star mergers being a major source of the 'heavy' (A>130) r-process isotopes. Parabolic collisions, especially those between neutron stars and black holes, eject substantially larger amounts of mass, and therefore cannot occur frequently without overproducing gala- ctic r-process matter. We also discuss the EM transients that are powered by radioactive decays within the ejecta ('macronovae'), and the radio flares that emerge when the ejecta dissipate their large kinetic energies in the ambient medium.

r -process nucleosynthesis from matter ejected in binary neutron star mergers [On r -process nucleosynthesis from matter ejected in binary neutron star mergers

DOE PAGES

Bovard, Luke; Martin, Dirk; Guercilena, Federico; ...

2017-12-05

Here, when binary systems of neutron stars merge, a very small fraction of their rest mass is ejected, either dynamically or secularly. This material is neutron-rich and its nucleosynthesis provides the astrophysical site for the production of heavy elements in the Universe, together with a kilonova signal confirming neutron-star mergers as the origin of short gamma-ray bursts. We perform full general-relativistic simulations of binary neutron-star mergers employing three different nuclear-physics equations of state (EOSs), considering both equal- and unequal-mass configurations, and adopting a leakage scheme to account for neutrino radiative losses. Using a combination of techniques, we carry out anmore » extensive and systematic study of the hydrodynamical, thermodynamical, and geometrical properties of the matter ejected dynamically, employing the WinNet nuclear-reaction network to recover the relative abundances of heavy elements produced by each configurations. Among the results obtained, three are particularly important. First, we find that, within the sample considered here, both the properties of the dynamical ejecta and the nucleosynthesis yields are robust against variations of the EOS and masses. Second, using a conservative but robust criterion for unbound matter, we find that the amount of ejected mass is ≲10 –3 M⊙, hence at least one order of magnitude smaller than what normally assumed in modelling kilonova signals. Finally, using a simplified and gray-opacity model we assess the observability of the infrared kilonova emission finding, that for all binaries the luminosity peaks around ~1/2 day in the H-band, reaching a maximum magnitude of –13, and decreasing rapidly after one day.« less

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;

r -process nucleosynthesis from matter ejected in binary neutron star mergers [On r -process nucleosynthesis from matter ejected in binary neutron star mergers

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

Bovard, Luke; Martin, Dirk; Guercilena, Federico

Here, when binary systems of neutron stars merge, a very small fraction of their rest mass is ejected, either dynamically or secularly. This material is neutron-rich and its nucleosynthesis provides the astrophysical site for the production of heavy elements in the Universe, together with a kilonova signal confirming neutron-star mergers as the origin of short gamma-ray bursts. We perform full general-relativistic simulations of binary neutron-star mergers employing three different nuclear-physics equations of state (EOSs), considering both equal- and unequal-mass configurations, and adopting a leakage scheme to account for neutrino radiative losses. Using a combination of techniques, we carry out anmore » extensive and systematic study of the hydrodynamical, thermodynamical, and geometrical properties of the matter ejected dynamically, employing the WinNet nuclear-reaction network to recover the relative abundances of heavy elements produced by each configurations. Among the results obtained, three are particularly important. First, we find that, within the sample considered here, both the properties of the dynamical ejecta and the nucleosynthesis yields are robust against variations of the EOS and masses. Second, using a conservative but robust criterion for unbound matter, we find that the amount of ejected mass is ≲10 –3 M⊙, hence at least one order of magnitude smaller than what normally assumed in modelling kilonova signals. Finally, using a simplified and gray-opacity model we assess the observability of the infrared kilonova emission finding, that for all binaries the luminosity peaks around ~1/2 day in the H-band, reaching a maximum magnitude of –13, and decreasing rapidly after one day.« less

Measurement of Surface Composition for the Icy Galilean Moons Via Neutral and Ion Mass Spectrometry from Orbit with JIMO

NASA Technical Reports Server (NTRS)

Wong, M.; Berthelier, J.; Carlson, R.; Cooper, J.; Johnson, R.; Jurac, S.; Leblanc, F.; Shematovich, V.

2003-01-01

In this paper, we will provide insights into mass spectrometer requirements. In addition, we will describe the modeling of the neutrals ejected from likely surface materials and their ionization rates in the Jovian environment. We will use such models to connect the mass spectra measurements of the freshly formed ions to surface composition. We will also discuss what possible compositional signatures are for endogenic materials other than water ice. Finally, since a goal is to identify material composition with surface features, we will describe the transport of neutrals ejected from the surface prior to detection by either an ion or neutral mass spectrometer.

Improved Miniaturized Linear Ion Trap Mass Spectrometer Using Lithographically Patterned Plates and Tapered Ejection Slit

NASA Astrophysics Data System (ADS)

Tian, Yuan; Decker, Trevor K.; McClellan, Joshua S.; Bennett, Linsey; Li, Ailin; De la Cruz, Abraham; Andrews, Derek; Lammert, Stephen A.; Hawkins, Aaron R.; Austin, Daniel E.

2018-02-01

We present a new two-plate linear ion trap mass spectrometer that overcomes both performance-based and miniaturization-related issues with prior designs. Borosilicate glass substrates are patterned with aluminum electrodes on one side and wire-bonded to printed circuit boards. Ions are trapped in the space between two such plates. Tapered ejection slits in each glass plate eliminate issues with charge build-up within the ejection slit and with blocking of ions that are ejected at off-nominal angles. The tapered slit allows miniaturization of the trap features (electrode size, slit width) needed for further reduction of trap size while allowing the use of substrates that are still thick enough to provide ruggedness during handling, assembly, and in-field applications. Plate spacing was optimized during operation using a motorized translation stage. A scan rate of 2300 Th/s with a sample mixture of toluene and deuterated toluene (D8) and xylenes (a mixture of o-, m-, p-) showed narrowest peak widths of 0.33 Th (FWHM).

A spectacular coronal mass ejection event and associated phenomena

NASA Astrophysics Data System (ADS)

Ma, Yuan; Li, Chun-Sheng; Song, Qian

Based on the data taken from S. G. D. and relevant simultaneous observations of solar radio bursts, gamma-ray emission and geophysical effects on June 15, 1991 the relationships among these phenomena are discussed in this paper. Through the analyses it is considered that proton events and GLE events occurred on June 15 in 1991, which were the geophysic responses caused by CME (V>=750 km/s). Simultaneous observation of the bursts at the centimetric and decimetric wavelengths can obtain the U-shape spectrum of speak fluxes, which is still one of the effective tools for predicting proton events and its production mechanism can be explained by using the acceleration of the direct current field parallel to the magnetic field in the electric current sheet formed in the process of the production of spray prominences. However, the process in which electrons are accelerated up to the high energy state remains to be explained. The whole event of June 15 1991, from the coronal matter ejection (or the spray prominences in active regions) to the production of various geophysic effects, has explained and verified.

Dynamical and Physical Properties of a Post-Coronal Mass Ejection Current Sheet

NASA Technical Reports Server (NTRS)

Ko, Yuan-Kuen; Raymond, John C.; Lin, Jun; Lawrence, Gareth; Li, Jing; Fludra, Andrzej

2003-01-01

In the eruptive process of the Kopp-Pneuman type, the closed magnetic field is stretched by the eruption so much that it is usually believed to be " open " to infinity. Formation of the current sheet in such a configuration makes it possible for the energy in the coronal magnetic field to quickly convert into thermal and kinetic energies and cause significant observational consequences, such as growing postflare/CME loop system in the corona, separating bright flare ribbons in the chromosphere, and fast ejections of the plasma and the magnetic flux. An eruption on 2002 January 8 provides us a good opportunity to look into these observational signatures of and place constraints on the theories of eruptions. The event started with the expansion of a magnetic arcade over an active region, developed into a coronal mass ejection (CME), and left some thin streamer-like structures with successively growing loop systems beneath them. The plasma outflow and the highly ionized states of the plasma inside these streamer-like structures, as well as the growing loops beneath them, lead us to conclude that these structures are associated with a magnetic reconnection site, namely, the current sheet, of this eruptive process. We combine the data from the Ultraviolet Coronagraph Spectrometer, Large Angle and Spectrometric Coronagraph Experiment, EUV Imaging Telescope, and Coronal Diagnostic Spectrometer on board the Solar and Heliospheric Observatory, as well is from the Mauna Loa Solar Observatory Mark IV K-coronameter, to investigate the morphological and dynamical properties of this event, as well as the physical properties of the current sheet. The velocity and acceleration of the CME reached up to 1800 km/s and 1 km/sq s, respectively. The acceleration is found to occur mainly at the lower corona (<2.76 Solar Radius). The post-CME loop systems showed behaviors of both postflare loops (upward motion with decreasing speed) and soft X-ray giant arches (upward motion with constant speed, or acceleration) according to the definition of Svestka. In the current sheet, the presence of highly ionized ions, such as Fe(+17) and Ca(+13), suggests temperature as high as (3-4) x 10(exp 6) K, and the plasma outflows have speeds ranging from 300 to 650 km/s. Absolute elemental abundances in the current sheet show a strong first ionization potential effect and have values similar to those found in the active region streamers. The magnetic field strength in the vicinity of the current sheet is found to be of the order of 1 G.

Prominence formation and ejection in cool stars

NASA Astrophysics Data System (ADS)

Villarreal D'Angelo, Carolina; Jardine, Moira; See, Victor

2018-03-01

The observational signatures of prominences have been detected in single and binary G and K type stars for many years now, but recently this has been extended to the M dwarf regime. Prominences carry away both mass and angular momentum when they are ejected and the impact of this mass on any orbiting planets may be important for the evolution of exoplanetary atmospheres. By means of the classification used in the massive star community, that involves knowledge of two parameters (the co-rotation and Alfvén radii, rK and rA), we have determined which cool stars could support prominences. From a model of mechanical support, we have determined that the prominence mass mp/M⋆ = (EM/EG)(r⋆/rK)2F where E_MB_\\star ^2r_\\star ^3 and E_G = GM_\\star ^2/r_\\star are magnetic and gravitational energies and F is a geometric factor. Our calculated masses and ejection frequencies (typically 1016 - 1017 g and 0.4 d, respectively) are consistent with observations and are sufficient to ensure that an exoplanet orbiting in the habitable zone of an M dwarf could suffer frequent impacts.

Inflows in the Inner White-light Corona: The Closing-down of Flux after Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Hess, P.; Wang, Y.-M.

2017-11-01

During times of high solar activity, the Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph C2 coronagraph has recorded multitudes of small features moving inward through its 2{--}6 {R}⊙ field of view. These outer-coronal inflows, which are concentrated around the heliospheric current sheet, tend to be poorly correlated with individual coronal mass ejection (CME) events. Using running-difference movies constructed from Solar Terrestrial Relations Observatory/COR1 coronagraph images taken during 2008-2014, we have identified large numbers of inward-moving features at heliocentric distances below 2 {R}⊙ , with the rate increasing with sunspot and CME activity. Most of these inner-coronal inflows are closely associated with CMEs, being observed during and in the days immediately following the eruptions. Here, we describe several examples of the pinching-off of tapered streamer structures in the wake of CMEs. This type of inflow event is characterized by a separation of the flow into incoming and outgoing components connected by a thin spike, which is interpreted as a continually elongating current sheet viewed edge-on; by the prior convergence of narrow rays toward the current sheet; and by a succession of collapsing loops that form a cusp-shaped structure at the base of the current sheet. The re-forming streamer overlies a growing post-eruption arcade that is visible in EUV images. These observations provide support for standard reconnection models for the formation/evolution of flux ropes during solar eruptive events. We suggest that inflow streams that occur over a relatively wide range of position angles result from the pinching-off of loop arcades whose axes are oriented parallel rather than perpendicular to the sky plane.

Flux-Rope Structure of Coronal Mass Ejections

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Nieves-Chinchilla, T.; Hidalgo, M.; Zhang, J.; Riley, P.; van Driel-Gesztelyi, L.; Mandrini, C. H.

2013-01-01

This Topical Issue (TI) of Solar Physics, devoted to the study of flux-rope structure in coronal mass ejections (CMEs), is based on two Coordinated Data Analysis Workshops (CDAWs) held in 2010 (20-23 September in Dan Diego, California, USA) and 2011 (5-9 September in Alcala, Spain). The primary purpose of the CDAWs was to address the question whether all CMEs have a flux rope structure. Each CDAW was attended by about 50 scientists interested in the origin, propagation, and interplanetary manifestation of CME phenomena.

Control and Signal Conditioning Circuits for E.I.R.M.A (Energetic Ion Retarding Mass Analyzer),

DTIC Science & Technology

1984-10-01

electrically isolated segment of the vehicle with respect to the main body of the vehicle containing the mass analyzer and other instruments. The...ambient plasma. The vehicle was to be charged positive by the ejection of electrons and negative by the positive ion ejection. Also, the operation of...ambient ions and the ener- getic ions emitted and created during the vehicle charging and dis- charging experiments. It also was intended to survey the

A Search for Early Optical Emission at Gamma-Ray Burst Locations by the Solar Mass Ejection Imager (SMEI)

NASA Technical Reports Server (NTRS)

Band, David L.; Buffington, Andrew; Jackson, Bernard V.; Hick, P. Paul; Smith, Aaron C.

2005-01-01

The Solar Mass Ejection Imager (SMEI) views nearly every point on the sky once every 102 minutes and can detect point sources as faint as R approx. 10th magnitude. Therefore, SMEI can detect or provide upper limits for the optical afterglow from gamma-ray bursts in the tens of minutes after the burst when different shocked regions may emit optically. Here we provide upper limits for 58 bursts between 2003 February and 2005 April.

Studying Geoeffective Interplanetary Coronal Mass Ejections Between the Sun and Earth: Space Weather Implications of Solar Mass Ejection Imager Observations

DTIC Science & Technology

2009-05-14

courtesy of I. Richardson. itoring, and adequate data latency would constitute a reliable tool for early warning of storms. Is] The first Earth...some ICMEs appear to undergo little change as they propagate outward from their low coronal origins, in this case out to 45° elongation. Such...and that, given much better data latency , a future SMEI-type heliospheric im- ager could be used to forecast the onset and maybe even the

How MAG4 Improves Space Weather Forecasting

NASA Technical Reports Server (NTRS)

Falconer, David; Khazanov, Igor; Barghouty, Nasser

2013-01-01

Dangerous space weather is driven by solar flares and Coronal Mass Ejection (CMEs). Forecasting flares and CMEs is the first step to forecasting either dangerous space weather or All Clear. MAG4 (Magnetogram Forecast), developed originally for NASA/SRAG (Space Radiation Analysis Group), is an automated program that analyzes magnetograms from the HMI (Helioseismic and Magnetic Imager) instrument on NASA SDO (Solar Dynamics Observatory), and automatically converts the rate (or probability) of major flares (M- and X-class), Coronal Mass Ejections (CMEs), and Solar Energetic Particle Events.

Compaction behaviour and mechanical strength of lactose-sodium starch glycolate and lactose-croscarmellose sodium binary tablets

NASA Astrophysics Data System (ADS)

Ashikin Yaakub, Nur; Shamsul Anuar, Mohd; Tahir, Suraya Mohd

2018-04-01

The focus of this study is to elucidate the effects of adding super disintegrants (SSG and Acdisol) to a filler (lactose) in terms of the compaction behaviour and mechanical strength of the formed binary tablets. The tablets were formed in a uniaxial die compaction process with compaction pressures ranging from 37.7MPa to 150.7 MPa. Consequently, the findings indicated that the increasing of the compaction pressure and the percentage mass composition of the super disintegrants would led to the increased in the strength of the tablets as well as their plastic energies, where this was more apparent for the case of the binary lactose/Acdisol tablets. In addition, as the compaction pressure increased, the maximum ejection pressure required to eject the tablet from the die cavity also increased. In contrast, a decreased in the maximum ejection pressure was observed as the composition of both super disintegrants increased in the lactose-super disintegrant binary tablets. In conclusion, the addition of super disintegrant; SSG with lactose and Acdisol with lactose; would enhanced the mechanical strength of lactose based tablets especially for the case of acdisol-lactose binary tablets in the experimental conditions adopted in this current work.

The free energies of partially open coronal magnetic fields

NASA Technical Reports Server (NTRS)

Low, B. C.; Smith, D. F.

1993-01-01

A simple model of the low corona is examined in terms of a static polytropic atmosphere in equilibrium with a global magnetic field. The question posed is whether magnetostatic states with partially open magnetic fields may contain magnetic energies in excess of those in fully open magnetic fields. Based on the analysis presented here, it is concluded that the cross-field electric currents in the pre-eruption corona are a viable source of the bulk of the energies in a mass ejection and its associated flare.

Tracking Nonradial Motions and Azimuthal Expansions of Interplanetary CMEs with the Solar Mass Ejection Imager

DTIC Science & Technology

2010-01-01

from Sun to Earth • Provide an all-sky view, updated every orbit • Detect signal at 1% of background ( zodiacal light and stars) The SMEI uses 3...hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and...currently valid OMB control number PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 15-06-2010 RF.PRTNT > Q. C 4

Ulysses Data Analysis: Magnetic Topology of Heliospheric Structures

NASA Technical Reports Server (NTRS)

Crooker, Nancy

2001-01-01

In this final technical report on research funded by a NASA grant, a project overview is given by way of summaries on nine published papers. Research has included: 1) Using suprathermal electron data to study heliospheric magnetic structures; 2) Analysis of magnetic clouds, coronal mass ejections (CME), and the heliospheric current sheet (HCS); 3) Analysis of the corotating interaction region (CIR) which develop from interactions between solar wind streams of different velocities; 4) Use of Ulysses data in the interpretation of heliospheric events and phenomena.

Formation of black hole x-ray binaries in globular clusters

NASA Astrophysics Data System (ADS)

Kremer, Kyle; Chatterjee, Sourav; Rodriguez, Carl; Rasio, Frederic

2018-01-01

We explore the formation of mass-transferring binary systems containing black holes within globular clusters. We show that it is possible to form mass-transferring binaries with main sequence, giant, and white dwarf companions with a variety of orbital parameters in globular clusters spanning a large range in present-day properties. We show that the presence of mass-transferring black hole systems has little correlation with the total number of black holes within the cluster at any time. In addition to mass-transferring binaries retained within their host clusters at late times, we also examine the black hole and neutron star binaries that are ejected from their host clusters. These ejected systems may contribute to the low-mass x-ray binary population in the galactic field.

A New Variety of CMEs: Streamer Puffs from Compact Ejective Flares

NASA Technical Reports Server (NTRS)

Sterling, Alphonse C.; Bemporad, A.; Moore, R. L.; Poletto, G.

2005-01-01

We present SOHO EIT, UVCS and LASCO observations of recurrent (6 --- 8 events per day) narrow (angular widths of about 3 --- 10 degrees) Coronal Mass Ejections (CMEs) which occurred over 2002 November 26--29. The active region where the ejections originate is near the base of a coronal streamer that appears to be unperturbed by the events and keeps stable in time; hence we interpret the observed events as a new class of recursive narrow CMEs that we call "streamer puffs." EIT 304 angstrom (He II) images indicate that the puffs result from compact ejective flares embedded in the streamer, with the ejections from the flares having velocities 100 --- 200 kilometers per second. Most ejections are closely correlated with coronal "jets" seen at 1.7 solar radii in the UVCS data, and a subset of these ejections and jets correspond to streamer puffs observed in LASCO coronagraph images. There are, however, more compact flares and jets than streamer puffs during the observation period, indicating that only a subset of the flare-associated ejections are energetic enough to escape into the heliosphere.

Effect of substrate thickness on ejection of phenylalanine molecules adsorbed on free-standing graphene bombarded by 10 keV C60

NASA Astrophysics Data System (ADS)

Golunski, M.; Verkhoturov, S. V.; Verkhoturov, D. S.; Schweikert, E. A.; Postawa, Z.

2017-02-01

Molecular dynamics computer simulations have been employed to investigate the effect of substrate thickness on the ejection mechanism of phenylalanine molecules deposited on free-standing graphene. The system is bombarded from the graphene side by 10 keV C60 projectiles at normal incidence and the ejected particles are collected both in transmission and reflection directions. It has been found that the ejection mechanism depends on the substrate thickness. At thin substrates mostly organic fragments are ejected by direct collisions between projectile atoms and adsorbed molecules. At thicker substrates interaction between deforming topmost graphene sheet and adsorbed molecules becomes more important. As this process is gentle and directionally correlated, it leads predominantly to ejection of intact molecules. The implications of the results to a novel analytical approach in Secondary Ion Mass Spectrometry based on ultrathin free-standing graphene substrates and a transmission geometry are discussed.

Electric-current Neutralization, Magnetic Shear, and Eruptive Activity in Solar Active Regions

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

Liu, Yang; Sun, Xudong; Török, Tibor

The physical conditions that determine whether or not solar active regions (ARs) produce strong flares and coronal mass ejections (CMEs) are not yet well understood. Here, we investigate the association between electric-current neutralization, magnetic shear along polarity inversion lines (PILs), and eruptive activity in four ARs: two emerging and two well-developed ones. We find that the CME-producing ARs are characterized by a strongly non-neutralized total current, while the total current in the ARs that did not produce CMEs is almost perfectly neutralized. The difference in the PIL shear between these two groups is much less pronounced, which suggests that themore » degree of current neutralization may serve as a better proxy for assessing the ability of ARs to produce CMEs.« less

Coronal Mass Ejections and Dimmings: A Comparative Study using MHD Simulations and SDO Observations

NASA Astrophysics Data System (ADS)

Jin, M.; Cheung, C. M. M.; DeRosa, M. L.; Nitta, N.; Schrijver, K.

2017-12-01

Solar coronal dimmings have been observed extensively in the past two decades. Due to their close association with coronal mass ejections (CMEs), there is a critical need to improve our understanding of the physical processes that cause dimmings and determine their relationship with CMEs. In this study, we investigate coronal dimmings by combining simulation and observational efforts. By utilizing a data-driven global magnetohydrodynamics model (AWSoM: Alfven-wave Solar Model), we simulate coronal dimmings resulting from different CME energetics and flux rope configurations. We synthesize the emissions of different EUV spectral bands/lines and compare with SDO/AIA and EVE observations. A detailed analysis of simulation and observation data suggests that although the transient dimming / brightening patterns could relate to plasma heating processes (either by adiabatic compression or reconnection), the long-lasting "core" and "remote" (also known as "secondary") dimmings both originate from regions with open/quasi-open fields and are caused by mass loss process. The mass loss in the remote dimming region is induced by CME-driven shock. Using metrics such as dimming depth, dimming slope, and recovery time, we investigate the relationship between dimmings and CME properties (e.g., CME mass, CME speed) in the simulation. Our result suggests that coronal dimmings encode important information about CME energetics, CME-driven shock properties, and magnetic configuration of erupting flux ropes. We also discuss how our knowledge about solar coronal dimmings could be extended to the study of stellar CMEs, which may prove important for exoplanet atmospheres and habitability but which are currently not observable.

The Hubble diagram for a system within dark energy: influence of some relevant quantities

NASA Astrophysics Data System (ADS)

Saarinen, J.; Teerikorpi, P.

2014-08-01

Aims: We study the influence of relevant quantities, including the density of dark energy (DE), to the predicted Hubble outflow around a system of galaxies. In particular, we are interested in the difference between two models: 1) the standard ΛCDM model, with the everywhere constant DE density, and 2) the "Swiss cheese model", where the Universe is as old as the standard model and the DE density is zero on short scales, including the environment of the system. Methods: We calculated the current predicted outflow patterns of dwarf galaxies around the Local Group-like system, using different values for the mass of the group, the local DE density, and the time of ejection of the dwarf galaxies, which are treated as test particles. These results are compared with the observed Hubble flow around the Local Group. Results: The predicted distance-velocity relations around galaxy groups are not very sensitive indicators of the DE density, owing to the observational scatter and the uncertainties caused by the mass used for the group and a range in the ejection times. In general, the Local Group outflow data agree with the local DE density being equal to the global one, if the Local Group mass is about 4 × 1012 M⊙; a lower mass ≲ 2 × 1012 M⊙ could suggest a zero local DE density. The dependence of the inferred DE density on the mass is a handicap in this and other common dynamical methods. This emphasizes the need to use different approaches together, for constraining the local DE density.

Dynamic evolution of recurrent mass ejections observed in H-alpha and C IV lines

NASA Technical Reports Server (NTRS)

Schmieder, B.; Mein, P.; Martres, M. J.; Tandberg-Hanssen, E.

1984-01-01

The mass ejections of 1 September, 1980 are studied from observations obtained with the MSDP spectrograph and with the Ultraviolet Spectrometer and Polarimeter aboard the Solar Maximum Mission satellite. The analysis is focused on observations in the chromospheric H-alpha line and the transition region C IV 1548 A line. It is noted that cold and hot material had the same projection, although the upward C IV velocity structure was more extended than the H-alpha one. It is shown that the observed contrast of the H-alpha absorbing structure can be interpreted in terms of a dynamic cloud model overlying the chromosphere. Radial velocities of 25-30 km/s and -40 km/s are estimated for the first and second phases of ejection, respectively.

Three-Dimensional Structure and Energy Balance of a Coronal Mass Ejection

NASA Technical Reports Server (NTRS)

Lee, J.-Y.; Raymond, J. C.; Ko, Y.-K.; Kim, K.-S.

2009-01-01

UVCS observed Doppler-shifted material of a partial halo coronal mass ejection (CME) on 2001 December 13. The observed ratio of [O VJ/O V] is a reliable density diagnostic important for assessing the state of the plasma. Earlier UVCS observations of CMEs found evidence that the ejected plasma is heated long after the eruption. This paper investigated the heating rates, which represent a significant fraction of the CME energy budget. The parameterized heating and radiative and adiabatic cooling have been used to evaluate the temperature evolution of the CME material with a time-dependent ionization state model. Continuous heating is required to match the UVCS observations. To match the O VI bright knots, a higher heating rate is required such that the heating energy is greater than the kinetic energy.

Force-feeding Black Holes

NASA Astrophysics Data System (ADS)

Begelman, Mitchell C.

2012-04-01

We propose that the growth of supermassive black holes is associated mainly with brief episodes of highly super-Eddington infall of gas ("hyperaccretion"). This gas is not swallowed in real time, but forms an envelope of matter around the black hole that can be swallowed gradually, over a much longer timescale. However, only a small fraction of the black hole mass can be stored in the envelope at any one time. We argue that any infalling matter above a few percent of the hole's mass is ejected as a result of the plunge in opacity at temperatures below a few thousand degrees kelvin, corresponding to the Hayashi track. The speed of ejection of this matter, compared to the velocity dispersion σ of the host galaxy's core, determines whether the ejected matter is lost forever or returns eventually to rejoin the envelope, from which it can be ultimately accreted. The threshold between matter recycling and permanent loss defines a relationship between the maximum black hole mass and σ that resembles the empirical M BH-σ relation.

Forbidden mass ranges for shower meteoroids

NASA Astrophysics Data System (ADS)

Moorhead, Althea V.

2017-10-01

Burns et al. (1979) use the parameter β to describe the ratio of radiation pressure to gravity for a particle in the Solar System. The central potential that these particles experience is effectively reduced by a factor of (1 - β), which in turn lowers the escape velocity. Burns et al. (1979) derived a simple expression for the value of β at which particles ejected from a comet follow parabolic orbits and thus leave the Solar System; we expand on this to derive an expression for critical β values that takes ejection velocity into account, assuming geometric optics. We use our expression to compute the critical β value and corresponding mass for cometary ejecta leading, trailing, and following the parent comet’s nucleus for 10 major meteor showers. Finally, we numerically solve for critical β values in the case of non-geometric optics. These values determine the mass regimes within which meteoroids are ejected from the Solar System and therefore cannot contribute to meteor showers.

Forbidden Mass Ranges for Shower Meteoroids

NASA Technical Reports Server (NTRS)

Moorhead, Althea V.

2017-01-01

Burns et al. (1979) use the parameter beta to describe the ratio of radiation pressure to gravity for a particle in the Solar System. The central potential that these particles experience is effectively reduced by a factor of (1- beta ), which in turn lowers the escape velocity. Burns et al. (1979) derived a simple expression for the value of beta at which particles ejected from a comet follow parabolic orbits and thus leave the Solar System; we expand on this to derive an expression for critical beta values that takes ejection velocity into account, assuming geometric optics. We use our expression to compute the critical value and corresponding mass for cometary ejecta leading, trailing, and following the parent comet's nucleus for 10 major meteor showers. Finally, we numerically solve for critical beta values in the case of non-geometric optics. These values determine the mass regimes within which meteoroids are ejected from the Solar System and therefore cannot contribute to meteor showers.

What Do High-Resolution EIT Waves Tell Us About CMEs?

NASA Technical Reports Server (NTRS)

Thompson, Barbara

2010-01-01

Although many studies have demonstrated that some coronal waves are not generated by corona) mass ejections, we have learned a great deal about the ability of corona) mass ejections to drive large-scale corona) waves, also called "EIT waves." We present new results based on EIT wave amplitude, timing, speed, and direction of propagation, with respect to their correlation with CME-related dimmings, speeds, locations and widths. Furthermore, we demonstrate the ability to correlate different aspects of EIT waves with some of the observed structure of CMEs observed in coronagraph data. Finally, we expand on the discussion of the types of wave modes that can be generated by a corona) mass ejection, and how these observations can serve as a diagnostic of the type of impulse a CME can deliver to the surrounding corona. These diagnostics are obtained by examining the motion of individual field lines, requiring high-resolution observations like those provided by TRACE and SDO/AIA.

Coronal Mass Ejection early-warning mission by solar-photon sailcraft

NASA Astrophysics Data System (ADS)

Vulpetti, Giovanni; Circi, Christian; Pino, Tommaso

2017-11-01

A preliminary investigation of the early warning of solar storms caused by Coronal Mass Ejection has been carried out. A long warning time could be obtained with a sailcraft synchronous with the Earth-Moon barycenter, and stationed well below the L1 point. In this paper, the theory of heliocentric synchronous sailcraft is set up, its perturbed orbit is analyzed, and a potential solution capable of providing an annual synchrony is carried out. A simple analysis of the response from a low-mass electrochromic actuator for the realization of station-keeping attitude maneuvers is put forwards, and an example of propellantless re-orientation maneuver is studied.

A new method for determining the mass ejected during the cometary outburst - Application to the Jupiter-family comets

NASA Astrophysics Data System (ADS)

Wesołowski, M.; Gronkowski, P.

2018-07-01

In the present article, we propose a new method of mass estimation which is ejected from a nucleus of a comet during its outburst of brightness. The phenomena of cometary outburst are often reported for both periodic and parabolic comets. The outburst of a comet brightness is a sudden increase in its brightness greater than one magnitude, average by 2-5 mag. This should not be confused with explosions such as outbreak of a bomb. The essence of the phenomenon is only a sudden brightening of the comet. Long-term observations and studies of this phenomenon lead to the conclusion that the very probable direct cause of the many outbursts is the ejection of the some part of surface layer of a comet's nucleus and an increase in the rate of a sublimation (Hughes (1990), Gronkowski (2007), Gronkowski and Wesołowski (2015)). The purpose of this article is presentation of a new simple method of the estimation of the mass which is ejected from the comet's nucleus during considered phenomenon. To estimate the mass released during an outburst, different probable coefficients of extinction for cometary matter was assumed. The scattering cross-sections of cometary grains were precisely calculated on the basis of Mie's theory. This method was applied to the outburst of a hypothetical comet X/PC belonging to the Jupiter-family comets and to the case of the comet 17P/Holmes outburst in 2007.

Interplanetary Coronal Mass Ejection effects on thermospheric density as inferred from International Space Station orbital data

NASA Astrophysics Data System (ADS)

Mendaza, T.; Blanco-Ávalos, J. J.; Martín-Torres, J.

2017-11-01

The solar activity induces long term and short term periodical variations in the dynamics and composition of Earth's atmosphere. The Sun also shows non periodical (i.e., impulsive) activity that reaches the planets orbiting around it. In particular, Interplanetary Coronal Mass Ejections (ICMEs) reach Earth and interact with its magnetosphere and upper neutral atmosphere. Nevertheless, the interaction with the upper atmosphere is not well characterized because of the absence of regular and dedicated in situ measurements at high altitudes; thus, current descriptions of the thermosphere are based on semi empirical models. In this paper, we present the total neutral mass densities of the thermosphere retrieved from the orbital data of the International Space Station (ISS) using the General Perturbation Method, and we applied these densities to routinely compiled trajectories of the ISS in low Earth orbit (LEO). These data are explicitly independent of any atmospheric model. Our density values are consistent with atmospheric models, which demonstrates that our method is reliable for the inference of thermospheric density. We have inferred the thermospheric total neutral density response to impulsive solar activity forcing from 2001 to the end of 2006 and determined how solar events affect this response. Our results reveal that the ISS orbital parameters can be used to infer the thermospheric density and analyze solar effects on the thermosphere.

Observations on obesity patterns in tetralogy of Fallot patients from childhood to adulthood.

PubMed

Briston, David A; Sabanayagam, Aarthi; Zaidi, Ali N

2017-07-01

Obesity is increasingly prevalent, and abnormal body mass index is a risk factor for cardiovascular disease. There are limited data published regarding body mass index and CHD. We tested the hypothesis that body mass index and obesity prevalence are increasing in patients with tetralogy of Fallot over time by analysing time since surgery, age, height, weight, and body mass index among tetralogy of Fallot patients and demographic data from age-matched controls. NYHA class and left ventricular ejection fraction were analysed in adults. Body mass index was categorised into normal, overweight, and obese in this single-centre, retrospective chart review. Data were collected from 137 tetralogy of Fallot patients (71 men:66 women), of whom 40 had body mass index >25 kg/m2. Tetralogy of Fallot patients aged <6 years had lower body mass index (15.9 versus 17.1; p=0.042) until 16-20 years of age (27.4 versus 25.4; p=0.43). For adult tetralogy of Fallot patients, the mean body mass index was 26.5 but not statistically significantly different from the control cohort. Obese adult patients had significantly higher average NYHA class compared with those of normal weight (p=0.03), but no differences in left ventricular ejection fraction by echocardiography (p=0.55) or cardiac MRI (p=0.26) were noted. Lower body mass index was observed initially in tetralogy of Fallot patients, but by late adolescence no significant difference was observed. As adults, tetralogy of Fallot patients with higher body mass index had increased NYHA class but similar left ventricular ejection fraction.

Ejection of the Massive Hydrogen-rich Envelope Timed with the Collapse of the Stripped SN 2014C

PubMed Central

Margutti, Raffaella; Kamble, A.; Milisavljevic, D.; Zapartas, E.; de Mink, S. E.; Drout, M.; Chornock, R.; Risaliti, G.; Zauderer, B. A.; Bietenholz, M.; Cantiello, M.; Chakraborti, S.; Chomiuk, L.; Fong, W.; Grefenstette, B.; Guidorzi, C.; Kirshner, R.; Parrent, J. T.; Patnaude, D.; Soderberg, A. M.; Gehrels, N. C.; Harrison, F.

2017-01-01

We present multi-wavelength observations of SN 2014C during the first 500 days. These observations represent the first solid detection of a young extragalactic stripped-envelope SN out to high-energy X-rays ~40 keV. SN 2014C shows ordinary explosion parameters (Ek ~ 1.8 × 1051 erg and Mej ~ 1.7 M⊙). However, over an ~1 year timescale, SN 2014C evolved from an ordinary hydrogen-poor supernova into a strongly interacting, hydrogen-rich supernova, violating the traditional classification scheme of type-I versus type-II SNe. Signatures of the SN shock interaction with a dense medium are observed across the spectrum, from radio to hard X-rays, and revealed the presence of a massive shell of ~1 M⊙of hydrogen-rich material at ~6 × 1016 cm. The shell was ejected by the progenitor star in the decades to centuries before collapse. This result challenges current theories of massive star evolution, as it requires a physical mechanism responsible for the ejection of the deepest hydrogen layer of H-poor SN progenitors synchronized with the onset of stellar collapse. Theoretical investigations point at binary interactions and/or instabilities during the last nuclear burning stages as potential triggers of the highly time-dependent mass loss. We constrain these scenarios utilizing the sample of 183 SNe Ib/c with public radio observations. Our analysis identifies SN 2014C-like signatures in ~10% of SNe. This fraction is reasonably consistent with the expectation from the theory of recent envelope ejection due to binary evolution if the ejected material can survive in the close environment for 103–104 years. Alternatively, nuclear burning instabilities extending to core C-burning might play a critical role. PMID:28684881

Particle orbits in model current sheet with a nonzero B(y) component

NASA Technical Reports Server (NTRS)

Zhu, Zhongwei; Parks, George

1993-01-01

The problem of charged particle motions in magnetotaillike model current sheets is revisited with the inclusion of a nonzero dawn-dusk magnetic field component. Three cases are examined considering both trapped and escaped orbits. The results show that a nonzero B(y) component disturbs the particle orbits by destroying orbit symmetry in the phase space about the z = 0 plane. It also changes the bounce frequency of particle orbits. The presence of B(y) thus modifies the Speiser orbits, particularly near the ejection phase. The process of ejected particle such as ejection direction, ejection velocity, and pitch angles are shown to depend on the sign of the charge.

Toward Understanding the Early Stags of an Impulsively Accelerated Coronal Mass Ejection

DTIC Science & Technology

2010-08-09

B. E., & Howard, R. A . 2009, ApJ, 702, 901 Wood, B. E., Karovska , M., Chen, J., Brueckner, G. E., Cook, J. W., & Howard, R. A . 1999, ApJ, 512, 484...ar X iv :1 00 8. 11 71 v1 [ as tr o- ph .S R ] 6 A ug 2 01 0 Astronomy & Astrophysics manuscript no. bubble c© ESO 2010 August 9, 2010 Toward...understanding the early stages of an impulsively accelerated coronal mass ejection SECCHI observations S. Patsourakos1, A . Vourlidas2, and B. Kliem3,4

The Expansion and Radial Speeds of Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Gopalswamy, N.; Dal Lago, A.; Yashiro, S.; Akiyama, S.

We show the relation between radial (V_{rad}) and expansion (V_{exp}) speeds of coronal mass ejections (CMEs) depends on the CME width. As CME width increases, {V_{rad}/V_{exp}} decreases from a value >1 to <1. For widths approaching 180°, the ratio approaches 0 if the cone has a flat base, while it approaches 0.5 if the base has a bulge (ice cream cone). The speed difference between the limb and disk halos and the spherical expansion of super fast CMEs can be explained by the width dependence.

A search for the origins of a possible coronal mass ejection in the low corona

NASA Technical Reports Server (NTRS)

Neupert, Werner M.

1988-01-01

Evidence for coronal and chromospheric precursors of a hypothesized coronal mass ejection is sought in OSO-7 observations of a filament eruption and the subsequent flare. Large-scale changes in the corona above the active region were clearly present for at least several minutes before the flare, culminating in the activation and eruption of two widely separated filaments; the eruption of one of the preexisting filaments initiated magnetic reconnections and energy releases in the low corona, generating the observed chromospheric flare.

Role of Ambient Solar Wind Conditions in CME evolution (P21)

NASA Astrophysics Data System (ADS)

Jadav, R.; Jadeja, A. K.; Iyer, K. N.

2006-11-01

ipsraj@yahoo.com Solar events are mainly responsible for producing storms at the Earth. Coronal Mass Ejection (CME) is a major cause for this. In this paper, Coronal Mass Ejections occurred during 1998-2004 are studied. Ambient solar wind does play some role in determining the effect of a CME. The effects produced at the Earth during the period 1999 2004 are considered and an attempt has been made to understand the role of ambient solar wind. This is to draw some conclusion about how some of the events become geo- effective.

Star formation in proto dwarf galaxies

NASA Technical Reports Server (NTRS)

Noriega-Crespo, A.; Bodenheimer, P.; Lin, D. N. C.; Tenorio-Tagle, G.

1990-01-01

The effects of the onset of star formation on the residual gas in primordial low-mass Local-Group dwarf spheroidal galaxies is studied by a series of hydrodynamical simulations. The models have concentrated on the effect of photoionization. The results indicate that photoionization in the presence of a moderate gas density gradient can eject most of the residual gas on a time scale of a few 10 to the 7th power years. High central gas density combined with inefficient star formation, however, may prevent mass ejection. The effect of supernova explosions is discussed briefly.

Mass Ejection from the Remnant of a Binary Neutron Star Merger: Viscous-radiation Hydrodynamics Study

NASA Astrophysics Data System (ADS)

Fujibayashi, Sho; Kiuchi, Kenta; Nishimura, Nobuya; Sekiguchi, Yuichiro; Shibata, Masaru

2018-06-01

We perform long-term general relativistic neutrino radiation hydrodynamics simulations (in axisymmetry) for a massive neutron star (MNS) surrounded by a torus, which is a canonical remnant formed after the binary neutron star merger. We take into account the effects of viscosity, which is likely to arise in the merger remnant due to magnetohydrodynamical turbulence. The viscous effect plays key roles for the mass ejection from the remnant in two phases of the evolution. In the first t ≲ 10 ms, a differential rotation state of the MNS is changed to a rigidly rotating state. A shock wave caused by the variation of its quasi-equilibrium state induces significant mass ejection of mass ∼(0.5–2.0) × {10}-2 {M}ȯ for the α-viscosity parameter of 0.01–0.04. For the longer-term evolution with ∼0.1–10 s, a significant fraction of the torus material is ejected. We find that the total mass of the viscosity-driven ejecta (≳ {10}-2 {M}ȯ ) could dominate over that of the dynamical ejecta (≲ {10}-2 {M}ȯ ). The electron fraction, Y e , of the ejecta is always high enough (Y e ≳ 0.25) that this post-merger ejecta is lanthanide-poor; hence, the opacity of the ejecta is likely to be ∼10–100 times lower than that of the dynamical ejecta. This indicates that the electromagnetic signal from the ejecta would be rapidly evolving, bright, and blue if it is observed from a small viewing angle (≲45°) for which the effect of the dynamical ejecta is minor.

Coronal Heating by Magnetic Explosions

NASA Technical Reports Server (NTRS)

Moore, Ronald L.; Falconer, D. A.; Porter, Jason G.; Suess, Steven T.

1998-01-01

We build a case for the persistent strong coronal heating in active regions and the pervasive quasi-steady heating of the corona in quiet regions and coronal holes being driven in basically the same way as the intense transient heating in solar flares: by explosions of sheared magnetic fields in the cores of initially closed bipoles. We begin by summarizing the observational case for exploding sheared core fields being the drivers of a wide variety of flare events, with and without coronal mass ejections. We conclude that the arrangement of an event's flare heating, whether there is a coronal mass ejection, and the time and place of the ejection relative to the flare heating are all largely determined by four elements of the form and action the magnetic field: (1) the arrangement of the impacted, interacting bipoles participating in the event, (2) which of these bipoles are active (have sheared core fields that explode) and which are passive (are heated by injection from impacted active bipoles), (3) which core field explodes first, and (4) which core-field explosions are confined within the closed field of their bipoles and which ejectively open their bipoles.

Explaining iPTF14hls as a common-envelope jets supernova

NASA Astrophysics Data System (ADS)

Soker, Noam; Gilkis, Avishai

2018-03-01

We propose a common-envelope jets supernova scenario for the enigmatic supernova iPTF14hls where a neutron star that spirals-in inside the envelope of a massive giant star accretes mass and launches jets that power the ejection of the circumstellar shell and a few weeks later the explosion itself. To account for the kinetic energy of the circumstellar gas and the explosion, the neutron star should accrete a mass of ≈0.3 M⊙. The tens× M⊙ of circumstellar gas that accounts for some absorption lines is ejected, while the neutron star orbits for about one to several weeks inside the envelope of the giant star. In the last hours of the interaction, the neutron star merges with the core, accretes mass, and launches jets that eject the core and the inner envelope to form the explosion itself and the medium where the supernova photosphere resides. The remaining neutron star accretes fallback gas and further powers the supernova. We attribute the 1954 pre-explosion outburst to an eccentric orbit and temporary mass accretion by the neutron star at periastron passage prior to the onset of the common envelope phase.

Simulating AIA observations of a flux rope ejection

NASA Astrophysics Data System (ADS)

Pagano, P.; Mackay, D. H.; Poedts, S.

2014-08-01

Context. Coronal mass ejections (CMEs) are the most violent phenomena observed on the Sun. Currently, extreme ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO) are providing new insights into the early phase of CME evolution. In particular, observations now show the ejection of magnetic flux ropes from the solar corona and how they evolve into CMEs. While this is the case, these observations are difficult to interpret in terms of basic physical mechanisms and quantities. To fully understand CMEs we need to compare equivalent quantities derived from both observations and theoretical models. This will aid in bridging the gap between observations and models. Aims: To this end, we aim to produce synthesised AIA observations from simulations of a flux rope ejection. To carry this out we include the role of thermal conduction and radiative losses, both of which are important for determining the temperature distribution of the solar corona during a CME. Methods: We perform a simulation where a flux rope is ejected from the solar corona. From the density and temperature of the plasma in the simulation we synthesise AIA observations. The emission is then integrated along the line of sight using the instrumental response function of AIA. Results: We sythesise observations of AIA in the channels at 304 Å, 171 Å, 335 Å, and 94 Å. The synthesised observations show a number of features similar to actual observations and in particular reproduce the general development of CMEs in the low corona as observed by AIA. In particular we reproduce an erupting and expanding arcade in the 304 Å and 171 Å channels with a high density core. Conclusions: The ejection of a flux rope reproduces many of the features found in the AIA observations. This work is therefore a step forward in bridging the gap between observations and models, and can lead to more direct interpretations of EUV observations in terms of flux rope ejections. We plan to improve the model in future studies in order to perform a more quantitative comparison. Movies associated with Figs. 3, 9, and 10 are available in electronic form at http://www.aanda.org

HUBBLE SPACE TELESCOPE FAR ULTRAVIOLET SPECTROSCOPY OF THE RECURRENT NOVA T PYXIDIS

PubMed Central

Godon, Patrick; Sion, Edward M.; Starrfield, Sumner; Livio, Mario; Williams, Robert E.; Woodward, Charles E.; Kuin, Paul; Page, Kim L.

2018-01-01

With six recorded nova outbursts, the prototypical recurrent nova T Pyxidis (T Pyx) is the ideal cataclysmic variable system to assess the net change of the white dwarf mass within a nova cycle. Recent estimates of the mass ejected in the 2011 outburst ranged from a few ~10−5 M⊙ to 3.3 × 10−4 M⊙, and assuming a mass accretion rate of 10−8−10−7 M⊙ yr−1 for 44 yr, it has been concluded that the white dwarf in T Pyx is actually losing mass. Using NLTE disk modeling spectra to fit our recently obtained Hubble Space Telescope COS and STIS spectra, we find a mass accretion rate of up to two orders of magnitude larger than previously estimated. Our larger mass accretion rate is due mainly to the newly derived distance of T Pyx (4.8 kpc, larger than the previous 3.5 kpc estimate), our derived reddening of E(B − V) = 0.35 (based on combined IUE and GALEX spectra), and NLTE disk modeling (compared to blackbody and raw flux estimates in earlier works). We find that for most values of the reddening (0.25 ≤ E(B−V) ≤ 0.50) and white dwarf mass (0.70 M⊙ ≤ Mwd ≤ 1.35 M⊙) the accreted mass is larger than the ejected mass. Only for a low reddening (~0.25 and smaller) combined with a large white dwarf mass (0.9 M⊙ and larger) is the ejected mass larger than the accreted one. However, the best results are obtained for a larger value of reddening. PMID:29430290

HUBBLE SPACE TELESCOPE FAR ULTRAVIOLET SPECTROSCOPY OF THE RECURRENT NOVA T PYXIDIS.

PubMed

Godon, Patrick; Sion, Edward M; Starrfield, Sumner; Livio, Mario; Williams, Robert E; Woodward, Charles E; Kuin, Paul; Page, Kim L

2014-04-01

With six recorded nova outbursts, the prototypical recurrent nova T Pyxidis (T Pyx) is the ideal cataclysmic variable system to assess the net change of the white dwarf mass within a nova cycle. Recent estimates of the mass ejected in the 2011 outburst ranged from a few ~10 -5 M ⊙ to 3.3 × 10 -4 M ⊙ , and assuming a mass accretion rate of 10 -8 -10 -7 M ⊙ yr -1 for 44 yr, it has been concluded that the white dwarf in T Pyx is actually losing mass. Using NLTE disk modeling spectra to fit our recently obtained Hubble Space Telescope COS and STIS spectra, we find a mass accretion rate of up to two orders of magnitude larger than previously estimated. Our larger mass accretion rate is due mainly to the newly derived distance of T Pyx (4.8 kpc, larger than the previous 3.5 kpc estimate), our derived reddening of E ( B - V ) = 0.35 (based on combined IUE and GALEX spectra), and NLTE disk modeling (compared to blackbody and raw flux estimates in earlier works). We find that for most values of the reddening (0.25 ≤ E ( B - V ) ≤ 0.50) and white dwarf mass (0.70 M ⊙ ≤ M wd ≤ 1.35 M ⊙ ) the accreted mass is larger than the ejected mass. Only for a low reddening (~0.25 and smaller) combined with a large white dwarf mass (0.9 M ⊙ and larger) is the ejected mass larger than the accreted one. However, the best results are obtained for a larger value of reddening.

The positive binding energy envelopes of low-mass helium stars

NASA Astrophysics Data System (ADS)

Hall, Philip D.; Jeffery, C. Simon

2018-04-01

It has been hypothesized that stellar envelopes with positive binding energy may be ejected if the release of recombination energy can be triggered and the calculation of binding energy includes this contribution. The implications of this hypothesis for the evolution of normal hydrogen-rich stars have been investigated, but the implications for helium stars - which may represent mass-transfer or merger remnants in binary star systems - have not. Making a set of model helium stars, we find that those with masses between 0.9 and 2.4 M⊙ evolve to configurations with positive binding energy envelopes. We discuss consequences of the ejection hypothesis for such stars, and possible observational tests of these predictions.

Halo CME

NASA Image and Video Library

2017-12-08

A giant cloud appears to expand outward from the sun in all directions in this image from Sept. 28, 2012, which is called a halo CME. This kind of image occurs when a CME moves toward Earth – as here – or directly away from it. Credit: ESA/NASA/SOHO CME WEEK: What To See in CME Images Two main types of explosions occur on the sun: solar flares and coronal mass ejections. Unlike the energy and x-rays produced in a solar flare – which can reach Earth at the speed of light in eight minutes – coronal mass ejections are giant, expanding clouds of solar material that take one to three days to reach Earth. Once at Earth, these ejections, also called CMEs, can impact satellites in space or interfere with radio communications. During CME WEEK from Sept. 22 to 26, 2014, we explore different aspects of these giant eruptions that surge out from the star we live with. When a coronal mass ejection blasts off the sun, scientists rely on instruments called coronagraphs to track their progress. Coronagraphs block out the bright light of the sun, so that the much fainter material in the solar atmosphere -- including CMEs -- can be seen in the surrounding space. CMEs appear in these images as expanding shells of material from the sun's atmosphere -- sometimes a core of colder, solar material (called a filament) from near the sun's surface moves in the center. But mapping out such three-dimensional components from a two-dimensional image isn't easy. Watch the slideshow to find out how scientists interpret what they see in CME pictures. The images in the slideshow are from the three sets of coronagraphs NASA currently has in space. One is on the joint European Space Agency and NASA Solar and Heliospheric Observatory, or SOHO. SOHO launched in 1995, and sits between Earth and the sun about a million miles away from Earth. The other two coronagraphs are on the two spacecraft of the NASA Solar Terrestrial Relations Observatory, or STEREO, mission, which launched in 2006. The two STEREO spacecraft are both currently viewing the far side of the sun. Together these instruments help scientists create a three-dimensional model of any CME as its journey unfolds through interplanetary space. Such information can show why a given characteristic of a CME close to the sun might lead to a given effect near Earth, or any other planet in the solar system...NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

STEREO's View

NASA Image and Video Library

2017-12-08

STEREO witnessed the March 5, 2013, CME from the side of the sun – Earth is far to the left of this picture. While the SOHO images show a halo CME, STEREO shows the CME clearly moving away from Earth. Credit: NASA/STEREO --- CME WEEK: What To See in CME Images Two main types of explosions occur on the sun: solar flares and coronal mass ejections. Unlike the energy and x-rays produced in a solar flare – which can reach Earth at the speed of light in eight minutes – coronal mass ejections are giant, expanding clouds of solar material that take one to three days to reach Earth. Once at Earth, these ejections, also called CMEs, can impact satellites in space or interfere with radio communications. During CME WEEK from Sept. 22 to 26, 2014, we explore different aspects of these giant eruptions that surge out from the star we live with. When a coronal mass ejection blasts off the sun, scientists rely on instruments called coronagraphs to track their progress. Coronagraphs block out the bright light of the sun, so that the much fainter material in the solar atmosphere -- including CMEs -- can be seen in the surrounding space. CMEs appear in these images as expanding shells of material from the sun's atmosphere -- sometimes a core of colder, solar material (called a filament) from near the sun's surface moves in the center. But mapping out such three-dimensional components from a two-dimensional image isn't easy. Watch the slideshow to find out how scientists interpret what they see in CME pictures. The images in the slideshow are from the three sets of coronagraphs NASA currently has in space. One is on the joint European Space Agency and NASA Solar and Heliospheric Observatory, or SOHO. SOHO launched in 1995, and sits between Earth and the sun about a million miles away from Earth. The other two coronagraphs are on the two spacecraft of the NASA Solar Terrestrial Relations Observatory, or STEREO, mission, which launched in 2006. The two STEREO spacecraft are both currently viewing the far side of the sun. Together these instruments help scientists create a three-dimensional model of any CME as its journey unfolds through interplanetary space. Such information can show why a given characteristic of a CME close to the sun might lead to a given effect near Earth, or any other planet in the solar system. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Twisted Fields

NASA Image and Video Library

2017-12-08

OHO captured this image of a CME from the side – but the structure looks much different from the classic light bulb CME. The filament of material bursting off the sun has a helical magnetic structure, which is unraveling like a piece of yarn during the eruption. Credit: ESA/NASA/SOHO..---..CME WEEK: What To See in CME Images Two main types of explosions occur on the sun: solar flares and coronal mass ejections. Unlike the energy and x-rays produced in a solar flare – which can reach Earth at the speed of light in eight minutes – coronal mass ejections are giant, expanding clouds of solar material that take one to three days to reach Earth. Once at Earth, these ejections, also called CMEs, can impact satellites in space or interfere with radio communications. During CME WEEK from Sept. 22 to 26, 2014, we explore different aspects of these giant eruptions that surge out from the star we live with. When a coronal mass ejection blasts off the sun, scientists rely on instruments called coronagraphs to track their progress. Coronagraphs block out the bright light of the sun, so that the much fainter material in the solar atmosphere -- including CMEs -- can be seen in the surrounding space. CMEs appear in these images as expanding shells of material from the sun's atmosphere -- sometimes a core of colder, solar material (called a filament) from near the sun's surface moves in the center. But mapping out such three-dimensional components from a two-dimensional image isn't easy. Watch the slideshow to find out how scientists interpret what they see in CME pictures. The images in the slideshow are from the three sets of coronagraphs NASA currently has in space. One is on the joint European Space Agency and NASA Solar and Heliospheric Observatory, or SOHO. SOHO launched in 1995, and sits between Earth and the sun about a million miles away from Earth. The other two coronagraphs are on the two spacecraft of the NASA Solar Terrestrial Relations Observatory, or STEREO, mission, which launched in 2006. The two STEREO spacecraft are both currently viewing the far side of the sun. Together these instruments help scientists create a three-dimensional model of any CME as its journey unfolds through interplanetary space. Such information can show why a given characteristic of a CME close to the sun might lead to a given effect near Earth, or any other planet in the solar system...NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Combined Images

NASA Image and Video Library

2017-12-08

Four different instruments on SOHO show a large CME on Nov. 6, 1997. The sun is at the center, with three coronagraph images of different sizes around it. The streaks of white light are from protons hitting the SOHO cameras producing a snowy effect typical of a significant flare. ..Credit: NASA/SOHO..---..CME WEEK: What To See in CME Images Two main types of explosions occur on the sun: solar flares and coronal mass ejections. Unlike the energy and x-rays produced in a solar flare – which can reach Earth at the speed of light in eight minutes – coronal mass ejections are giant, expanding clouds of solar material that take one to three days to reach Earth. Once at Earth, these ejections, also called CMEs, can impact satellites in space or interfere with radio communications. During CME WEEK from Sept. 22 to 26, 2014, we explore different aspects of these giant eruptions that surge out from the star we live with. When a coronal mass ejection blasts off the sun, scientists rely on instruments called coronagraphs to track their progress. Coronagraphs block out the bright light of the sun, so that the much fainter material in the solar atmosphere -- including CMEs -- can be seen in the surrounding space. CMEs appear in these images as expanding shells of material from the sun's atmosphere -- sometimes a core of colder, solar material (called a filament) from near the sun's surface moves in the center. But mapping out such three-dimensional components from a two-dimensional image isn't easy. Watch the slideshow to find out how scientists interpret what they see in CME pictures. The images in the slideshow are from the three sets of coronagraphs NASA currently has in space. One is on the joint European Space Agency and NASA Solar and Heliospheric Observatory, or SOHO. SOHO launched in 1995, and sits between Earth and the sun about a million miles away from Earth. The other two coronagraphs are on the two spacecraft of the NASA Solar Terrestrial Relations Observatory, or STEREO, mission, which launched in 2006. The two STEREO spacecraft are both currently viewing the far side of the sun. Together these instruments help scientists create a three-dimensional model of any CME as its journey unfolds through interplanetary space. Such information can show why a given characteristic of a CME close to the sun might lead to a given effect near Earth, or any other planet in the solar system...NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Deflected Propagation of Coronal Mass Ejections: One of the Key Issues in Space Weather Forecasting

NASA Astrophysics Data System (ADS)

Wang, Y.; Shen, C.; Zhuang, B.; Pan, Z.

2016-12-01

As the most important driver of severe space weather, coronal mass ejections (CMEs) and their geoeffectiveness have been studied intensively. Previous statistical studies have shown that not all the front-side halo CMEs are geoeffective, and not all non-recurrent geomagnetic storms can be tracked back to a CME. These phenomena may cause some failed predictions of the geoeffectiveness of CMEs. The recent notable event exhibiting such a failure was on 2015 March 15 when a fast CME originated from the west hemisphere. Space Weather Prediction Center (SWPC) of NOAA initially forecasted that the CME would at most cause a very minor geomagnetic disturbance labeled as G1. However, the CME produced the largest geomagnetic storm so far, at G4 level with the provisional Dst value of -223 nT, in the current solar cycle 24 [e.g., Kataoka et al., 2015; Wang et al., 2016]. Such an unexpected phenomenon naturally raises the first question for the forecasting of the geoeffectiveness of a CME, i.e., whether or not a CME will hit the Earth even though we know the source location and initial kinematic properties of the CME. A full understanding of the propagation trajectory, e.g., the deflected propagation, of a CME from the Sun to 1 AU is the key. With a few cases, we show the importance of the deflection effect in the space weather forecasting. An automated CME arrival forecasting system containing a deflected propagation model is presented. References:[1] Kataoka, R., D. Shiota, E. Kilpua, and K. Keika, Pileup accident hypothesis of magnetic storm on 17 March 2015, Geophys. Res. Lett., 42, 5155-5161, 2015.[2] Wang, Yuming, Quanhao Zhang, Jiajia Liu, Chenglong Shen, Fang Shen, Zicai Yang, T. Zic, B. Vrsnak, D. F. Webb, Rui Liu, S. Wang, Jie Zhang, Q. Hu, and B. Zhuang, On the Propagation of a Geoeffective Coronal Mass Ejection during March 15 - 17, 2015, J. Geophys. Res., accepted, doi:10.1002/2016JA022924, 2016.

r -process nucleosynthesis from matter ejected in binary neutron star mergers

NASA Astrophysics Data System (ADS)

Bovard, Luke; Martin, Dirk; Guercilena, Federico; Arcones, Almudena; Rezzolla, Luciano; Korobkin, Oleg

2017-12-01

When binary systems of neutron stars merge, a very small fraction of their rest mass is ejected, either dynamically or secularly. This material is neutron-rich and its nucleosynthesis provides the astrophysical site for the production of heavy elements in the Universe, together with a kilonova signal confirming neutron-star mergers as the origin of short gamma-ray bursts. We perform full general-relativistic simulations of binary neutron-star mergers employing three different nuclear-physics equations of state (EOSs), considering both equal- and unequal-mass configurations, and adopting a leakage scheme to account for neutrino radiative losses. Using a combination of techniques, we carry out an extensive and systematic study of the hydrodynamical, thermodynamical, and geometrical properties of the matter ejected dynamically, employing the WinNet nuclear-reaction network to recover the relative abundances of heavy elements produced by each configurations. Among the results obtained, three are particularly important. First, we find that, within the sample considered here, both the properties of the dynamical ejecta and the nucleosynthesis yields are robust against variations of the EOS and masses. Second, using a conservative but robust criterion for unbound matter, we find that the amount of ejected mass is ≲10-3 M⊙, hence at least one order of magnitude smaller than what normally assumed in modelling kilonova signals. Finally, using a simplified and gray-opacity model we assess the observability of the infrared kilonova emission finding, that for all binaries the luminosity peaks around ˜1 /2 day in the H -band, reaching a maximum magnitude of -13 , and decreasing rapidly after one day.

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

Morscher, Meagan; Pattabiraman, Bharath; Rodriguez, Carl

Our current understanding of the stellar initial mass function and massive star evolution suggests that young globular clusters (GCs) may have formed hundreds to thousands of stellar-mass black holes (BHs), the remnants of stars with initial masses from ∼20-100 M {sub ☉}. Birth kicks from supernova explosions may eject some BHs from their birth clusters, but most should be retained. Using a Monte Carlo method we investigate the long-term dynamical evolution of GCs containing large numbers of stellar BHs. We describe numerical results for 42 models, covering a broad range of realistic initial conditions, including up to 1.6 × 10{supmore » 6} stars. In almost all models we find that significant numbers of BHs (up to ∼10{sup 3}) are retained all the way to the present. This is in contrast to previous theoretical expectations that most BHs should be ejected dynamically within a few gigayears The main reason for this difference is that core collapse driven by BHs (through the Spitzer {sup m}ass segregation instability{sup )} is easily reverted through three-body processes, and involves only a small number of the most massive BHs, while lower-mass BHs remain well-mixed with ordinary stars far from the central cusp. Thus the rapid segregation of stellar BHs does not lead to a long-term physical separation of most BHs into a dynamically decoupled inner core, as often assumed previously. Combined with the recent detections of several BH X-ray binary candidates in Galactic GCs, our results suggest that stellar BHs could still be present in large numbers in many GCs today, and that they may play a significant role in shaping the long-term dynamical evolution and the present-day dynamical structure of many clusters.« less

FORCE-FEEDING BLACK HOLES

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

Begelman, Mitchell C., E-mail: mitch@jila.colorado.edu

2012-04-10

We propose that the growth of supermassive black holes is associated mainly with brief episodes of highly super-Eddington infall of gas ({sup h}yperaccretion{sup )}. This gas is not swallowed in real time, but forms an envelope of matter around the black hole that can be swallowed gradually, over a much longer timescale. However, only a small fraction of the black hole mass can be stored in the envelope at any one time. We argue that any infalling matter above a few percent of the hole's mass is ejected as a result of the plunge in opacity at temperatures below amore » few thousand degrees kelvin, corresponding to the Hayashi track. The speed of ejection of this matter, compared to the velocity dispersion {sigma} of the host galaxy's core, determines whether the ejected matter is lost forever or returns eventually to rejoin the envelope, from which it can be ultimately accreted. The threshold between matter recycling and permanent loss defines a relationship between the maximum black hole mass and {sigma} that resembles the empirical M{sub BH}-{sigma} relation.« less

Variations of the Electron Fluxes in the Terrestrial Radiation Belts Due To the Impact of Corotating Interaction Regions and Interplanetary Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Benacquista, R.; Boscher, D.; Rochel, S.; Maget, V.

2018-02-01

In this paper, we study the variations of the radiation belts electron fluxes induced by the interaction of two types of solar wind structures with the Earth magnetosphere: the corotating interaction regions and the interplanetary coronal mass ejections. We use a statistical method based on the comparison of the preevent and postevent fluxes. Applied to the National Oceanic and Atmospheric Administration-Polar Operational Environmental Satellites data, this gives us the opportunity to extend previous studies focused on relativistic electrons at geosynchronous orbit. We enlighten how corotating interaction regions and Interplanetary Coronal Mass Ejections can impact differently the electron belts depending on the energy and the L shell. In addition, we provide a new insight concerning these variations by considering their amplitude. Finally, we show strong relations between the intensity of the magnetic storms related to the events and the variation of the flux. These relations concern both the capacity of the events to increase the flux and the deepness of these increases.

KINEMATIC TREATMENT OF CORONAL MASS EJECTION EVOLUTION IN THE SOLAR WIND

NASA Technical Reports Server (NTRS)

Riley, Pete; Crooker, N. U.

2004-01-01

We present a kinematic study of the evolution of coronal mass ejections (CMEs) in the solar wind. Specifically, we consider the effects of (1) spherical expansion and (2) uniform expansion due to pressure gradients between the interplanetary CME (ICME) and the ambient solar wind. We compare these results with an MHD model that allows us to isolate these effects h m the combined kinematic and dynamical effects, which are included in MHD models. They also provide compelling evidence that the fundamental cross section of so-called "force-free" flux ropes (or magnetic clouds) is neither circular or elliptical, but rather a convex-outward, "pancake" shape. We apply a force-free fit to the magnetic vectors from the MHD simulation to assess how the distortion of the flux rope affects the fit. In spite of these limitations, force-free fits, which are straightforward to apply, do provide an important description of a number of parameters, including the radial dimension, orientation, and chirality of the ICME. Subject headings: MHD - solar wind - Sun: activity - Sun: corona - Sun: coronal mass ejections (CMEs) - On-line material color figures Sun: magnetic fields

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

Dipole Excitation With A Paul Ion Trap Mass Spectrometer

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

MacAskill, J. A.; Madzunkov, S. M.; Chutjian, A.

Preliminary results are presented for the use of an auxiliary radiofrequency (rf) excitation voltage in combination with a high purity, high voltage rf generator to perform dipole excitation within a high precision Paul ion trap. These results show the effects of the excitation frequency over a continuous frequency range on the resultant mass spectra from the Paul trap with particular emphasis on ion ejection times, ion signal intensity, and peak shapes. Ion ejection times are found to decrease continuously with variations in dipole frequency about several resonant values and show remarkable symmetries. Signal intensities vary in a complex fashion withmore » numerous resonant features and are driven to zero at specific frequency values. Observed intensity variations depict dipole excitations that target ions of all masses as well as individual masses. Substantial increases in mass resolution are obtained with resolving powers for nitrogen increasing from 114 to 325.« less

Bipolar nebulae and mass loss from red giant stars

NASA Technical Reports Server (NTRS)

Cohen, M.

1985-01-01

Observations of several bipolar nebulae are used to learn something of the nature of mass loss from the probable red-giant progenitors of these nebulae. Phenomena discussed are: (1) probable GL 2688's optical molecular emissions; (2) newly discovered very high velocity knots along the axis of OH 0739 - 14, which reveal evidence for mass ejections of + or 300 km/s from the M9 III star embedded in this nebula; (3) the bipolar structure of three extreme carbon stars, and the evidence for periodic mass ejection in IRC + 30219, also at high speed (about 80 km/s); and (4) the curious cool TiO-rich region above Parsamian 13, which may represent the very recent shedding of photospheric material from a cool, oxygen-rich giant. Several general key questions about bipolar nebulae that relate to the process of mass loss from their progenitor stars are raised.

Solar Drivers for Space Weather Operations (Invited)

NASA Astrophysics Data System (ADS)

White, S. M.

2013-12-01

Most space weather effects can be tied back to the Sun, and major research efforts are devoted to understanding the physics of the relevant phenomena with a long-term view of predicting their occurrence. This talk will focus on the current state of knowledge regarding the solar drivers of space weather, and in particular the connection between the science and operational needs. Topics covered will include the effects of solar ionizing flux on communications and navigation, radio interference, flare forecasting, the solar wind and the arrival of coronal mass ejections at Earth.

The unprecedented metamorphosis of SN2014C: from a H-stripped explosion to a strongly interacting supernova

NASA Astrophysics Data System (ADS)

Margutti, Raffaella

2015-09-01

Mass loss in massive stars is one of the least understood yet fundamental aspects of stellar evolution. HOW and WHEN do massive stars lose their H-envelopes? This central question motivates this proposal. We request a modest investment of Chandra time over 3 years to map the unique situation of the interaction of a H-stripped SN2014C with a H-rich shell ejected by its progenitor star, as part of our extensive radio-to-gamma-ray follow-up. Our goal is to constrain the density profile and proximity of the ejected material, and hence the mass-loss history of the progenitor star. Unlike all other H-stripped SNe, the radio and X-ray emission of SN14C is still increasing at 400 days, giving us the unprecedented opportunity to constrain the epoch ejection of H-rich material in fine detail.

Fast Litho-panspermia in the Habitable Zone of the TRAPPIST-1 System

NASA Astrophysics Data System (ADS)

Krijt, Sebastiaan; Bowling, Timothy J.; Lyons, Richard J.; Ciesla, Fred J.

2017-04-01

With several short-period, Earth-mass planets in the habitable zone (HZ), the TRAPPIST-1 system potentially allows litho-panspermia to take place on very short timescales. We investigate the efficiency and speed of inter-planetary material transfer resulting from impacts onto the HZ planets. By simulating trajectories of impact ejecta from their moment of ejection until (re-)accretion, we find that transport between the HZ planets is fastest for ejection velocities around and just above planetary escape velocity. At these ejection velocities, ∼10% of the ejected material reaches another HZ planet within 102 years, indicating litho-panspermia can be 4–5 orders of magnitude faster in TRAPPIST-1 than in the solar system.

A Monte Carlo-type simulation toolbox for Solar System small body dynamics: Application to the October Draconids

NASA Astrophysics Data System (ADS)

Kastinen, D.; Kero, J.

2017-09-01

We present the current status and first results from a Monte Carlo-type simulation toolbox for Solar System small body dynamics. We also present fundamental methods for evaluating the results of this type of simulations using convergence criteria. The calculations consider a body in the Solar System with a mass loss mechanism that generates smaller particles. In our application the body, or parent body, is a comet and the mass loss mechanism is a sublimation process. In order to study mass propagation from parent bodies to Earth, we use the toolbox to sample the uncertainty distributions of relevant comet parameters and to find the resulting Earth influx distributions. The initial distributions considered represent orbital elements, sublimation distance, cometary and meteoroid densities, comet and meteoroid sizes and cometary surface activity. Simulations include perturbations from all major planets, radiation pressure and the Poynting-Robertson effect. In this paper we present the results of an initial software validation performed by producing synthetic versions of the 1933, 1946, 2011 and 2012 October Draconids meteor outbursts and comparing them with observational data and previous models. The synthetic meteor showers were generated by ejecting and propagating material from the recognized parent body of the October Draconids; the comet 21P/Giacobini-Zinner. Material was ejected during 17 perihelion passages between 1866 and 1972. Each perihelion passage was sampled with 50 clones of the parent body, all producing meteoroid streams. The clones were drawn from a multidimensional Gaussian distribution on the orbital elements, with distribution variances proportional to observational uncertainties. In the simulations, each clone ejected 8000 particles. Each particle was assigned an individual weight proportional to the mass loss it represented. This generated a total of 6.7 million test particles, out of which 43 thousand entered the Earth's Hill sphere during 1900-2020 and were considered encounters. The simulation reproduces the predictions and observations of the 1933, 1946, 2011 and 2012 October Draconids, including the unexpected but measured deviation of the meteoroid mass index from a power law in 2012 as compared to 2011. We show that when convergence is sufficient in the simulation, the fraction between two encountered mass distributions is independent of the assumed input mass distribution. Finally, we predict an outburst for the 2018 October Draconids with a peak on October 8-9 that could be up to twice as large as the 2011 and 2012 outbursts.

Current evolution of meteoroids

NASA Technical Reports Server (NTRS)

Dohnanyi, J. S.

1973-01-01

The observed mass distribution of meteoroids at 1 AU from the sun is briefly reviewed in a survey that ranges over the bulk of the mass spectrum from micrometeoroids to meteorite parent objects. The evolution of meteoroids under the influence of collisions, planetary perturbations, the Poynting-Robertson effect and radiation pressure is then discussed. Most micrometeoroids are expelled from the solar system by radiation pressure shortly after their production as secondary ejecta during impact by larger objects or as dust ejected by comets. Particles that survive will eventually be swept out by the Poynting-Robertson effect. Meteoroids in the radio and photographic ranges are destroyed in collisions faster than they can be replaced by the production of secondary fragments during collisions between larger objects.

Dynamic comparisons of piezoelectric ejecta diagnostics

NASA Astrophysics Data System (ADS)

Buttler, W. T.; Zellner, M. B.; Olson, R. T.; Rigg, P. A.; Hixson, R. S.; Hammerberg, J. E.; Obst, A. W.; Payton, J. R.; Iverson, A.; Young, J.

2007-03-01

We investigate the quantitative reliability and precision of three different piezoelectric technologies for measuring ejected areal mass from shocked surfaces. Specifically we performed ejecta measurements on Sn shocked at two pressures, P ≈215 and 235 kbar. The shock in the Sn was created by launching a impactor with a powder gun. We self-compare and cross-compare these measurements to assess the ability of these probes to precisely determine the areal mass ejected from a shocked surface. We demonstrate the precision of each technology to be good, with variabilities on the order of ±10%. We also discuss their relative accuracy.

Investigation of the Large Scale Evolution and Topology of Coronal Mass Ejections in the Solar Wind

NASA Technical Reports Server (NTRS)

Riley, Peter

1999-01-01

This investigation is concerned with the large-scale evolution and topology of Coronal Mass Ejections (CMEs) in the solar wind. During this reporting period we have analyzed a series of low density intervals in the ACE (Advanced Composition Explorer) plasma data set that bear many similarities to CMEs. We have begun a series of 3D, MHD (Magnetohydrodynamics) coronal models to probe potential causes of these events. We also edited two manuscripts concerning the properties of CMEs in the solar wind. One was re-submitted to the Journal of Geophysical Research.

A new method to quantify the effects of baryons on the matter power spectrum

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

Schneider, Aurel; Teyssier, Romain, E-mail: aurel@physik.uzh.ch, E-mail: teyssier@physik.uzh.ch

2015-12-01

Future large-scale galaxy surveys have the potential to become leading probes for cosmology provided the influence of baryons on the total mass distribution is understood well enough. As hydrodynamical simulations strongly depend on details in the feedback implementations, no unique and robust predictions for baryonic effects currently exist. In this paper we propose a baryonic correction model that modifies the density field of dark-matter-only N-body simulations to mimic the effects of baryons from any underlying adopted feedback recipe. The model assumes haloes to consist of 4 components: 1- hot gas in hydrostatical equilibrium, 2- ejected gas from feedback processes, 3-more » central galaxy stars, and 4- adiabatically relaxed dark matter, which all modify the initial dark-matter-only density profiles. These altered profiles allow to define a displacement field for particles in N-body simulations and to modify the total density field accordingly. The main advantage of the baryonic correction model is to connect the total matter density field to the observable distribution of gas and stars in haloes, making it possible to parametrise baryonic effects on the matter power spectrum. We show that the most crucial quantities are the mass fraction of ejected gas and its corresponding ejection radius. The former controls how strongly baryons suppress the power spectrum, while the latter provides a measure of the scale where baryonic effects become important. A comparison with X-ray and Sunyaev-Zel'dovich cluster observations suggests that baryons suppress wave modes above k∼0.5 h/Mpc with a maximum suppression of 10-25 percent around k∼ 2 h/Mpc. More detailed observations of the gas in the outskirts of groups and clusters are required to decrease the large uncertainties of these numbers.« less

A two-step initial mass function:. Consequences of clustered star formation for binary properties

NASA Astrophysics Data System (ADS)

Durisen, R. H.; Sterzik, M. F.; Pickett, B. K.

2001-06-01

If stars originate in transient bound clusters of moderate size, these clusters will decay due to dynamic interactions in which a hard binary forms and ejects most or all the other stars. When the cluster members are chosen at random from a reasonable initial mass function (IMF), the resulting binary characteristics do not match current observations. We find a significant improvement in the trends of binary properties from this scenario when an additional constraint is taken into account, namely that there is a distribution of total cluster masses set by the masses of the cloud cores from which the clusters form. Two distinct steps then determine final stellar masses - the choice of a cluster mass and the formation of the individual stars. We refer to this as a ``two-step'' IMF. Simple statistical arguments are used in this paper to show that a two-step IMF, combined with typical results from dynamic few-body system decay, tends to give better agreement between computed binary characteristics and observations than a one-step mass selection process.

Method for increasing the dynamic range of mass spectrometers

DOEpatents

Belov, Mikhail; Smith, Richard D.; Udseth, Harold R.

2004-09-07

A method for enhancing the dynamic range of a mass spectrometer by first passing a sample of ions through the mass spectrometer having a quadrupole ion filter, whereupon the intensities of the mass spectrum of the sample are measured. From the mass spectrum, ions within this sample are then identified for subsequent ejection. As further sampling introduces more ions into the mass spectrometer, the appropriate rf voltages are applied to a quadrupole ion filter, thereby selectively ejecting the undesired ions previously identified. In this manner, the desired ions may be collected for longer periods of time in an ion trap, thus allowing better collection and subsequent analysis of the desired ions. The ion trap used for accumulation may be the same ion trap used for mass analysis, in which case the mass analysis is performed directly, or it may be an intermediate trap. In the case where collection is an intermediate trap, the desired ions are accumulated in the intermediate trap, and then transferred to a separate mass analyzer. The present invention finds particular utility where the mass analysis is performed in an ion trap mass spectrometer or a Fourier transform ion cyclotron resonance mass spectrometer.

Analysis of powerful heliospheric non-geoeffective event of the 28 April, 2015 in muon flux

NASA Astrophysics Data System (ADS)

Astapov, I. I.; Barbashina, N. S.; Veselovsky, I. S.; Osetrova, N. V.; Petrukhin, A. A.; Shutenko, V. V.

2016-02-01

The coronal mass ejection (CME) that occurred on April 28, 2015 is analyzed. The passage of the ejection did not cause geoeffective disturbances in the near-Earth space. At the same time, the CME had a significant impact on the flux of cosmic rays registered on the Earth's surface by the muon hodoscope URAGAN.

Studies of hydrodynamic events in stellar evolution. 3: Ejection of planetary nebulae

NASA Technical Reports Server (NTRS)

Sparks, W. M.; Kutter, G. S.

1973-01-01

The dynamic behavior of the H-rich envelope (0.101 solar mass) of an evolved star (1.1 solar mass) as the luminosity rises to 19000 solar luminosity during the second ascent of the red giant branch. For luminosities in the range 3100 L 19000 solar luminosity the H-rich envelope pulsates like a long-period variable (LPV) with periods of the order of a year. As L reaches 19000 solar luminosity, the entire H-rich envelope is ejected as a shell with speeds of a few 10 km/s. The ejection occurs on a timescale of a few LPV pulsation periods. This ejection is associated with the formation of a planetary nebula. The computations are based on an implicit hydrodynamic computer code. T- and RHO-dependent opacities and excitation and ionization energies are included. As the H-rich envelope is accelerated off the stellar core, the gap between envelope and core is approximated by a vacuum, filled with radiation. Across the vacuum, the luminosity is conserved and the anisotropy of the radiation is considered as well as the solid angle subtended by the remnant star at the inner surface of the H-rich envelope. Spherical symmetry and the diffusion approximation are assumed.

Connecting Coronal Mass Ejections to Their Solar Active Region Sources: Combining Results from the HELCATS and FLARECAST Projects

NASA Astrophysics Data System (ADS)

Murray, Sophie A.; Guerra, Jordan A.; Zucca, Pietro; Park, Sung-Hong; Carley, Eoin P.; Gallagher, Peter T.; Vilmer, Nicole; Bothmer, Volker

2018-04-01

Coronal mass ejections (CMEs) and other solar eruptive phenomena can be physically linked by combining data from a multitude of ground-based and space-based instruments alongside models; however, this can be challenging for automated operational systems. The EU Framework Package 7 HELCATS project provides catalogues of CME observations and properties from the Heliospheric Imagers on board the two NASA/STEREO spacecraft in order to track the evolution of CMEs in the inner heliosphere. From the main HICAT catalogue of over 2,000 CME detections, an automated algorithm has been developed to connect the CMEs observed by STEREO to any corresponding solar flares and active-region (AR) sources on the solar surface. CME kinematic properties, such as speed and angular width, are compared with AR magnetic field properties, such as magnetic flux, area, and neutral line characteristics. The resulting LOWCAT catalogue is also compared to the extensive AR property database created by the EU Horizon 2020 FLARECAST project, which provides more complex magnetic field parameters derived from vector magnetograms. Initial statistical analysis has been undertaken on the new data to provide insight into the link between flare and CME events, and characteristics of eruptive ARs. Warning thresholds determined from analysis of the evolution of these parameters is shown to be a useful output for operational space weather purposes. Parameters of particular interest for further analysis include total unsigned flux, vertical current, and current helicity. The automated method developed to create the LOWCAT catalogue may also be useful for future efforts to develop operational CME forecasting.

A high-contrast imaging survey of nearby red supergiants

NASA Astrophysics Data System (ADS)

Scicluna, Peter; Siebenmorgen, Ralf; Blommaert, Joris; Kemper, Francisca; Wesson, Roger; Wolf, Sebastian

2017-11-01

Mass-loss in cool supergiants remains poorly understood, but is one of the key elements in their evolution towards exploding as supernovae. Some show evidence of asymmetric mass loss, discrete mass-ejections and outbursts, with seemingly little to distinguish them from more quiescent cases. To explore the prevalence of discrete ejections and companions we have conducted a high-constrast survey using near-infrared imaging and optical polarimetric imaging of nearby southern and equatorial red supergiants, using the extreme adaptive optics instrument SPHERE, which was designed to image planets around nearby stars. We present the initial results of this survey, including the detection of large (500 nm) dust grains in the ejecta of VY CMa and a candidate dusty torus aligned with the maser ring of VX Sgr. We briefly speculate on the consequences for our understanding of mass loss in these extreme stars.

Response of Jupiter's Aurora to Plasma Mass Loading Rate Monitored by the Hisaki Satellite During Io's Volcanic Event

NASA Astrophysics Data System (ADS)

Kimura, T.; Yoshioka, K.; Tsuchiya, F.; Hiraki, Y.; Tao, C.; Murakami, G.; Yamazaki, A.; Fujimoto, M.; Badman, S. V.; Delamere, P. A.; Bagenal, F.

2016-12-01

Plasma production and transfer processes in the planetary and stellar magnetospheres are essential for understanding the space environments around the celestial bodies. It is hypothesized that the mass of plasma loaded from Io's volcano to Jupiter's rotating magnetosphere is recurrently ejected as blobs from the distant tail region of the magnetosphere. The plasma ejections are possibly triggered by the magnetic reconnections, which are followed by the particle energization, bursty planetward plasma flow, and resultant auroral emissions. They are referred to as the 'energetic events'. However, there has been no evidence that the plasma mass loading actually causes the energetic events because of lack of the simultaneous observation of them. This study presents that the recurrent transient auroras, which are possibly representative for the energetic events, are closely associated with the mass loading. Continuous monitoring of the aurora and Io plasma torus indicates onset of the recurrent auroras when accumulation of the loaded plasma mass reaches the canonical total mass of the magnetosphere. This onset condition implies that the fully filled magnetosphere overflows the plasma mass accompanying the energetic events.

Large Prominence Eruption [video

NASA Image and Video Library

2014-10-07

The STEREO (Behind) spacecraft captured this large prominence and corona mass ejection as they erupted into space (Sept. 26, 2014). By combining images from three instruments, scientists can see the eruption itself (in extreme UV light) as well as follow its progression over the period of about 13 hours with its two coronagraphs. Credit: NASA/Goddard/STEREO The STEREO (Behind) spacecraft captured this large prominence and corona mass ejection as they erupted into space (Sept. 26, 2014). By combining images from three instruments, scientists can see the eruption itself (in extreme UV light) as well as follow its progression over the period of about 13 hours with its two coronagraphs.

Large Prominence Eruption (October 3, 2014)

NASA Image and Video Library

2017-12-08

The STEREO (Behind) spacecraft captured this large prominence and corona mass ejection as they erupted into space (Sept. 26, 2014). By combining images from three instruments, scientists can see the eruption itself (in extreme UV light) as well as follow its progression over the period of about 13 hours with its two coronagraphs. Credit: NASA/Goddard/STEREO The STEREO (Behind) spacecraft captured this large prominence and corona mass ejection as they erupted into space (Sept. 26, 2014). By combining images from three instruments, scientists can see the eruption itself (in extreme UV light) as well as follow its progression over the period of about 13 hours with its two coronagraphs.

Magnetohydrodynamic Modeling of Coronal Evolution and Disruption

NASA Technical Reports Server (NTRS)

Linker, Jon

2002-01-01

Flux cancellation, defined observationally as the mutual disappearance of magnetic fields of opposite polarity at the neutral line separating them, has been found to occur frequently at the site of filaments (called prominences when observed on the limb of the Sun). During the second year of this project, we have studied theoretically the role that flux cancellation may play in prominence formation, prominence eruption, and the initiation of coronal mass ejections. This work has been in published in two papers: "Magnetic Field Topology in Prominences" by Lionello, Mikic, Linker, and Amari and "Flux Cancellation and Coronal Mass Ejections" by Linker, Mikic, Riley, Lionello, Amari, and Odstrcil.

Effects of interplanetary coronal mass ejections on the transport of nano-dust generated in the inner solar system

NASA Astrophysics Data System (ADS)

O'Brien, Leela; Juhász, Antal; Sternovsky, Zoltan; Horányi, Mihály

2018-07-01

This article reports on an investigation of the effect of interplanetary coronal mass ejections (ICMEs) on the transport and delivery of nano-dust to 1 AU. Charged nanometer-sized dust particles are expected to be generated close to the Sun and interact strongly with the solar wind as well as solar transient events. Nano-dust generated outside of ∼0.2 AU are picked up and transported away from the Sun due to the electromagnetic forces exerted by the solar wind. A numerical model has been developed to calculate the trajectories of nano-dust through their interaction with the solar wind and explore the potential for their detection near Earth's orbit (Juhasz and Horanyi, 2013). Here, we extend the model to include the interaction with interplanetary coronal mass ejections. We report that ICMEs can greatly alter nano-dust trajectories, their transport to 1 AU, and their distribution near Earth's orbit. The smallest nano-dust (<10 nm) can be delivered to 1 AU in high concentration. Thus, the nature of the interaction between nano-dust and ICMEs could potentially be revealed by simultaneous measurements of nano-dust fluxes and solar wind particles/magnetic fields.

Coronal mass ejection kinematics deduced from white light (Solar Mass Ejection Imager) and radio (Wind/WAVES) observations

NASA Astrophysics Data System (ADS)

Reiner, M. J.; Jackson, B. V.; Webb, D. F.; Mizuno, D. R.; Kaiser, M. L.; Bougeret, J.-L.

2005-09-01

White-light and radio observations are combined to deduce the coronal and interplanetary kinematics of a fast coronal mass ejection (CME) that was ejected from the Sun at about 1700 UT on 2 November 2003. The CME, which was associated with an X8.3 solar flare from W56°, was observed by the Mauna Loa and Solar and Heliospheric Observatory (SOHO) Large-Angle Spectrometric Coronograph (LASCO) coronagraphs to 14 R⊙. The measured plane-of-sky speed of the LASCO CME was 2600 km s-1. To deduce the kinematics of this CME, we use the plane-of-sky white light observations from both the Solar Mass Ejection Imager (SMEI) all-sky camera on board the Coriolis spacecraft and the SOHO/LASCO coronagraph, as well as the frequency drift rate of the low-frequency radio data and the results of the radio direction-finding analysis from the WAVES experiment on the Wind spacecraft. In agreement with the in situ observations for this event, we find that both the white light and radio observations indicate that the CME must have decelerated significantly beginning near the Sun and continuing well into the interplanetary medium. More specifically, by requiring self-consistency of all the available remote and in situ data, together with a simple, but not unreasonable, assumption about the general characteristic of the CME deceleration, we were able to deduce the radial speed and distance time profiles for this CME as it propagated from the Sun to 1 AU. The technique presented here, which is applicable to mutual SMEI/WAVES CME events, is expected to provide a more complete description and better quantitative understanding of how CMEs propagate through interplanetary space, as well as how the radio emissions, generated by propagating CME/shocks, relate to the shock and CME. This understanding can potentially lead to more accurate predictions for the onset times of space weather events, such as those that were observed during this unique period of intense solar activity.

Towards an initial mass function for giant planets

NASA Astrophysics Data System (ADS)

Carrera, Daniel; Davies, Melvyn B.; Johansen, Anders

2018-07-01

The distribution of exoplanet masses is not primordial. After the initial stage of planet formation, gravitational interactions between planets can lead to the physical collision of two planets, or the ejection of one or more planets from the system. When this occurs, the remaining planets are typically left in more eccentric orbits. In this report we demonstrate how the present-day eccentricities of the observed exoplanet population can be used to reconstruct the initial mass function of exoplanets before the onset of dynamical instability. We developed a Bayesian framework that combines data from N-body simulations with present-day observations to compute a probability distribution for the mass of the planets that were ejected or collided in the past. Integrating across the exoplanet population, one can estimate the initial mass function of exoplanets. We find that the ejected planets are primarily sub-Saturn-type planets. While the present-day distribution appears to be bimodal, with peaks around ˜1MJ and ˜20M⊕, this bimodality does not seem to be primordial. Instead, planets around ˜60M⊕ appear to be preferentially removed by dynamical instabilities. Attempts to reproduce exoplanet populations using population synthesis codes should be mindful of the fact that the present population may have been depleted of sub-Saturn-mass planets. Future observations may reveal that young giant planets have a more continuous size distribution with lower eccentricities and more sub-Saturn-type planets. Lastly, there is a need for additional data and for more research on how the system architecture and multiplicity might alter our results.

Toward an initial mass function for giant planets

NASA Astrophysics Data System (ADS)

Carrera, Daniel; Davies, Melvyn B.; Johansen, Anders

2018-05-01

The distribution of exoplanet masses is not primordial. After the initial stage of planet formation, gravitational interactions between planets can lead to the physical collision of two planets, or the ejection of one or more planets from the system. When this occurs, the remaining planets are typically left in more eccentric orbits. In this report we demonstrate how the present-day eccentricities of the observed exoplanet population can be used to reconstruct the initial mass function of exoplanets before the onset of dynamical instability. We developed a Bayesian framework that combines data from N-body simulations with present-day observations to compute a probability distribution for the mass of the planets that were ejected or collided in the past. Integrating across the exoplanet population, one can estimate the initial mass function of exoplanets. We find that the ejected planets are primarily sub-Saturn type planets. While the present-day distribution appears to be bimodal, with peaks around ˜1MJ and ˜20M⊕, this bimodality does not seem to be primordial. Instead, planets around ˜60M⊕ appear to be preferentially removed by dynamical instabilities. Attempts to reproduce exoplanet populations using population synthesis codes should be mindful of the fact that the present population may have been been depleted of sub-Saturn-mass planets. Future observations may reveal that young giant planets have a more continuous size distribution with lower eccentricities and more sub-Saturn type planets. Lastly, there is a need for additional data and for more research on how the system architecture and multiplicity might alter our results.

WR 148: identifying the companion of an extreme runaway massive binary*

NASA Astrophysics Data System (ADS)

Munoz, Melissa; Moffat, Anthony F. J.; Hill, Grant M.; Shenar, Tomer; Richardson, Noel D.; Pablo, Herbert; St-Louis, Nicole; Ramiaramanantsoa, Tahina

2017-05-01

WR 148 (HD 197406) is an extreme runaway system considered to be a potential candidate for a short-period (4.3173 d) rare WR + compact object binary. Provided with new high-resolution, high signal-to-noise spectra from the Keck observatory, we determine the orbital parameters for both the primary WR and the secondary, yielding respective projected orbital velocity amplitudes of 88.1 ± 3.8 km s-1 and 79.2 ± 3.1 km s-1 and implying a mass ratio of 1.1 ± 0.1. We then apply the shift-and-add technique to disentangle the spectra and obtain spectra compatible with a WN7ha and an O4-6 star. Considering an orbital inclination of ˜67°, derived from previous polarimetry observations, the system's total mass would be a mere 2-3M_{⊙}, an unprecedented result for a putative massive binary system. However, a system comprising a 37 M_{⊙} secondary (typical mass of an O5V star) and a 33 M_{⊙} primary (given the mass ratio) would infer an inclination of ˜18°. We therefore reconsider the previous methods of deriving the orbital inclination based on time-dependent polarimetry and photometry. While the polarimetric results are inconclusive requiring better data, the photometric results favour low inclinations. Finally, we compute WR 148's space velocity and retrace the runaway's trajectory back to the Galactic plane (GP). With an ejection velocity of 198 ± 27 km s-1 and a travel time of 4.7 ± 0.8 Myr to reach its current location, WR 148 was most likely ejected via dynamical interactions in a young cluster.

Ejection of the Massive Hydrogen-rich Envelope Timed with the Collapse of the Stripped SN 2014C

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

Margutti, Raffaella; Kamble, A.; Milisavljevic, D.

2017-02-01

We present multi-wavelength observations of SN 2014C during the first 500 days. These observations represent the first solid detection of a young extragalactic stripped-envelope SN out to high-energy X-rays ∼40 keV. SN 2014C shows ordinary explosion parameters ( E {sub k} ∼ 1.8 × 10{sup 51} erg and M {sub ej} ∼ 1.7 M{sub ⊙}). However, over an ∼1 year timescale, SN 2014C evolved from an ordinary hydrogen-poor supernova into a strongly interacting, hydrogen-rich supernova, violating the traditional classification scheme of type-I versus type-II SNe. Signatures of the SN shock interaction with a dense medium are observed across the spectrum,more » from radio to hard X-rays, and revealed the presence of a massive shell of ∼1 M {sub ⊙} of hydrogen-rich material at ∼6 × 10{sup 16} cm. The shell was ejected by the progenitor star in the decades to centuries before collapse. This result challenges current theories of massive star evolution, as it requires a physical mechanism responsible for the ejection of the deepest hydrogen layer of H-poor SN progenitors synchronized with the onset of stellar collapse. Theoretical investigations point at binary interactions and/or instabilities during the last nuclear burning stages as potential triggers of the highly time-dependent mass loss. We constrain these scenarios utilizing the sample of 183 SNe Ib/c with public radio observations. Our analysis identifies SN 2014C-like signatures in ∼10% of SNe. This fraction is reasonably consistent with the expectation from the theory of recent envelope ejection due to binary evolution if the ejected material can survive in the close environment for 10{sup 3}–10{sup 4} years. Alternatively, nuclear burning instabilities extending to core C-burning might play a critical role.« less

DC Potentials Applied to an End-cap Electrode of a 3-D Ion Trap for Enhanced MSn Functionality

PubMed Central

Prentice, Boone M.; Xu, Wei; Ouyang, Zheng; McLuckey, Scott A.

2010-01-01

The effects of the application of various DC magnitudes and polarities to an end-cap of a 3-D quadrupole ion trap throughout a mass spectrometry experiment were investigated. Application of a monopolar DC field was achieved by applying a DC potential to the exit end-cap electrode, while maintaining the entrance end-cap electrode at ground potential. Control over the monopolar DC magnitude and polarity during time periods associated with ion accumulation, mass analysis, ion isolation, ion/ion reaction, and ion activation can have various desirable effects. Included amongst these are increased ion capture efficiency, increased ion ejection efficiency during mass analysis, effective isolation of ions using lower AC resonance ejection amplitudes, improved temporal control of the overlap of oppositely charged ion populations, and the performance of “broad-band” collision induced dissociation (CID). These results suggest general means to improve the performance of the 3-D ion trap in a variety of mass spectrometry and tandem mass spectrometry experiments. PMID:21927573

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

Bein, B. M.; Temmer, M.; Veronig, A. M.

Using combined STEREO-A and STEREO-B EUVI, COR1, and COR2 data, we derive deprojected coronal mass ejection (CME) kinematics and CME ''true'' mass evolutions for a sample of 25 events that occurred during 2007 December to 2011 April. We develop a fitting function to describe the CME mass evolution with height. The function considers both the effect of the coronagraph occulter, at the beginning of the CME evolution, and an actual mass increase. The latter becomes important at about 10-15 R{sub Sun} and is assumed to mostly contribute up to 20 R{sub Sun }. The mass increase ranges from 2% tomore » 6% per R{sub Sun} and is positively correlated to the total CME mass. Due to the combination of COR1 and COR2 mass measurements, we are able to estimate the ''true'' mass value for very low coronal heights (<3 R{sub Sun }). Based on the deprojected CME kinematics and initial ejected masses, we derive the kinetic energies and propelling forces acting on the CME in the low corona (<3 R{sub Sun }). The derived CME kinetic energies range between 1.0-66 Multiplication-Sign 10{sup 23} J, and the forces range between 2.2-510 Multiplication-Sign 10{sup 14} N.« less

Farside Halo

NASA Image and Video Library

2017-12-08

There's no way to tell from this SOHO image whether the halo CME on March 5, 2013, originated from the front or far of the sun. But the STEREO spacecraft were watching the sun from the sides and showed it was from the far side. The bright planet is Venus. Credit: NASA/SOHO CME WEEK: What To See in CME Images Two main types of explosions occur on the sun: solar flares and coronal mass ejections. Unlike the energy and x-rays produced in a solar flare – which can reach Earth at the speed of light in eight minutes – coronal mass ejections are giant, expanding clouds of solar material that take one to three days to reach Earth. Once at Earth, these ejections, also called CMEs, can impact satellites in space or interfere with radio communications. During CME WEEK from Sept. 22 to 26, 2014, we explore different aspects of these giant eruptions that surge out from the star we live with. When a coronal mass ejection blasts off the sun, scientists rely on instruments called coronagraphs to track their progress. Coronagraphs block out the bright light of the sun, so that the much fainter material in the solar atmosphere -- including CMEs -- can be seen in the surrounding space. CMEs appear in these images as expanding shells of material from the sun's atmosphere -- sometimes a core of colder, solar material (called a filament) from near the sun's surface moves in the center. But mapping out such three-dimensional components from a two-dimensional image isn't easy. Watch the slideshow to find out how scientists interpret what they see in CME pictures. The images in the slideshow are from the three sets of coronagraphs NASA currently has in space. One is on the joint European Space Agency and NASA Solar and Heliospheric Observatory, or SOHO. SOHO launched in 1995, and sits between Earth and the sun about a million miles away from Earth. The other two coronagraphs are on the two spacecraft of the NASA Solar Terrestrial Relations Observatory, or STEREO, mission, which launched in 2006. The two STEREO spacecraft are both currently viewing the far side of the sun. Together these instruments help scientists create a three-dimensional model of any CME as its journey unfolds through interplanetary space. Such information can show why a given characteristic of a CME close to the sun might lead to a given effect near Earth, or any other planet in the solar system...NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Multiple Views

NASA Image and Video Library

2017-12-08

This CME image from Oct. 7, 2012, captured by two instruments on STEREO, shows the eruption from its base out into space. The base of the CME near the sun is seen in extreme ultraviolet light emitted directly from the solar material; the growing loop is seen in visible light. Credit: NASA/STEREO CME WEEK: What To See in CME Images Two main types of explosions occur on the sun: solar flares and coronal mass ejections. Unlike the energy and x-rays produced in a solar flare – which can reach Earth at the speed of light in eight minutes – coronal mass ejections are giant, expanding clouds of solar material that take one to three days to reach Earth. Once at Earth, these ejections, also called CMEs, can impact satellites in space or interfere with radio communications. During CME WEEK from Sept. 22 to 26, 2014, we explore different aspects of these giant eruptions that surge out from the star we live with. When a coronal mass ejection blasts off the sun, scientists rely on instruments called coronagraphs to track their progress. Coronagraphs block out the bright light of the sun, so that the much fainter material in the solar atmosphere -- including CMEs -- can be seen in the surrounding space. CMEs appear in these images as expanding shells of material from the sun's atmosphere -- sometimes a core of colder, solar material (called a filament) from near the sun's surface moves in the center. But mapping out such three-dimensional components from a two-dimensional image isn't easy. Watch the slideshow to find out how scientists interpret what they see in CME pictures. The images in the slideshow are from the three sets of coronagraphs NASA currently has in space. One is on the joint European Space Agency and NASA Solar and Heliospheric Observatory, or SOHO. SOHO launched in 1995, and sits between Earth and the sun about a million miles away from Earth. The other two coronagraphs are on the two spacecraft of the NASA Solar Terrestrial Relations Observatory, or STEREO, mission, which launched in 2006. The two STEREO spacecraft are both currently viewing the far side of the sun. Together these instruments help scientists create a three-dimensional model of any CME as its journey unfolds through interplanetary space. Such information can show why a given characteristic of a CME close to the sun might lead to a given effect near Earth, or any other planet in the solar system...NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

"Cold" synthesis of carbon from polyvinyl chloride with the use of an electron beam ejected into the atmosphere

NASA Astrophysics Data System (ADS)

Kryazhev, Yu. G.; Vorob'ev, M. S.; Koval', N. N.; Trenikhin, M. V.; Solodovnichenko, V. S.; Sulakshin, S. A.; Likholobov, V. A.

2016-10-01

This work shows the possibility in principle of forming hydrocarbon structures in polyvinyl chloride films free of admixtures and polyvinyl chloride films modified with 5-mass % ferrocene via a radiation chemical transformation in the atmosphere with the use of an electron accelerator with a plasma cathode operating in the pulsed-periodic mode maximal electron energy no higher than 160 keV, pulse length of 40 μs, and current density of 5 mA/cm2. According to the results of semiquantitative X-ray microanalysis, an irradiated polyvinyl chloride film free of admixtures contains 92 of carbon, 6 of oxygen, and 2 mass % of chlorine; the irradiated polyvinyl chloride is an amorphous carbon material. A possible mechanism of the phenomenon is discussed.

The Peculiar Behavior of Halo Coronal Mass Ejections in Solar Cycle 24

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Xie, H.; Akiyama, S.; Makela, P.; Yashiro, S.; Michalek, G.

2015-01-01

We report on the remarkable finding that the halo coronal mass ejections (CMEs) in cycle 24 are more abundant than in cycle 23, although the sunspot number in cycle 24 has dropped by approx. 40%. We also find that the distribution of halo-CME source locations is different in cycle 24: the longitude distribution of halos is much flatter with the number of halos originating at a central meridian distance greater than or equal to 60deg twice as large as that in cycle 23. On the other hand, the average speed and associated soft X-ray flare size are the same in both cycles, suggesting that the ambient medium into which the CMEs are ejected is significantly different. We suggest that both the higher abundance and larger central meridian longitudes of halo CMEs can be explained as a consequence of the diminished total pressure in the heliosphere in cycle 24. The reduced total pressure allows CMEs to expand more than usual making them appear as halos.

Evidence for a Current Sheet Forming in the Wake of a Coronal Mass Ejection from Multi-Viewpoint Coronagraph Observations

DTIC Science & Technology

2010-10-05

Cargill et al. 2006; Linton and Longcope 2006; Onofri, Isliker, & Vlahos , L. 2006, Vršnak et al. 2009). A second difficulty comes from the very nature of...Brueckner G. E., Howard, R. A., Koomen, M. J., et al., 1995, SoPh, 162, 357 Cargill P. J., Vlahos L., Turkmani R., Galsgaard K., Isliker H., 2006, SSRv, 124...ApJ, 642, 1177 Litvinenko, Y. E. 1996, ApJ, 462, 997 McKenzie D. E., Hudson H. S., 1999, ApJ, 519, L93 Onofri, M., Isliker, H., & Vlahos , L. 2006

Observations of the Formation, Development, and Structure of a Current Sheet in an Eruptive Solar Flare

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

Seaton, Daniel B.; Darnel, Jonathan M.; Bartz, Allison E., E-mail: daniel.seaton@noaa.gov

2017-02-01

We present Atmospheric Imaging Assembly observations of a structure we interpret as a current sheet associated with an X4.9 flare and coronal mass ejection that occurred on 2014 February 25 in NOAA Active Region 11990. We characterize the properties of the current sheet, finding that the sheet remains on the order of a few thousand kilometers thick for much of the duration of the event and that its temperature generally ranged between 8 and 10 MK. We also note the presence of other phenomena believed to be associated with magnetic reconnection in current sheets, including supra-arcade downflows and shrinking loops.more » We estimate that the rate of reconnection during the event was M{sub A} ≈ 0.004–0.007, a value consistent with model predictions. We conclude with a discussion of the implications of this event for reconnection-based eruption models.« less

Departure from corotation of the Io plasma torus - Local plasma production

NASA Technical Reports Server (NTRS)

Pontius, D. H., Jr.; Hill, T. W.

1982-01-01

The departure of the Jovian magnetosphere from rigid corotation is adequately explained by outward plasma transport at distances where L is greater than approximately 10. The departure of 5% observed in the Io plasma torus, however, is too large to be accounted for simply by plasma transport. Local plasma production is proposed as the main factor determining the corotation lag in the torus. The outward pick-up current provided by ionization of neutral atoms is calculated and related to the current produced in the ionosphere by the corotation lag. This leads to an expression giving the corotation lag of the torus as a function of radial distance. Charge transfer is found to be an important process, allowing the majority of the torus mass to be ejected from the magnetosphere in a neutral state. Thus, the mass loading rate is found to be several times that inferred from examination of the corotation lag associated with outward plasma transport.

In-N-Out: The Gas Cycle from Dwarfs to Spiral Galaxies

NASA Astrophysics Data System (ADS)

Christensen, Charlotte R.; Davé, Romeel; Governato, Fabio; Pontzen, Andrew; Brooks, Alyson; Munshi, Ferah; Quinn, Thomas; Wadsley, James

2016-06-01

We examine the scalings of galactic outflows with halo mass across a suite of 20 high-resolution cosmological zoom galaxy simulations covering halo masses in the range {10}9.5{--}{10}12 {M}⊙ . These simulations self-consistently generate outflows from the available supernova energy in a manner that successfully reproduces key galaxy observables, including the stellar mass-halo mass, Tully-Fisher, and mass-metallicity relations. We quantify the importance of ejective feedback to setting the stellar mass relative to the efficiency of gas accretion and star formation. Ejective feedback is increasingly important as galaxy mass decreases; we find an effective mass loading factor that scales as {v}{{circ}}-2.2, with an amplitude and shape that are invariant with redshift. These scalings are consistent with analytic models for energy-driven wind, based solely on the halo potential. Recycling is common: about half of the outflow mass across all galaxy masses is later reaccreted. The recycling timescale is typically ˜1 Gyr, virtually independent of halo mass. Recycled material is reaccreted farther out in the disk and with typically ˜2-3 times more angular momentum. These results elucidate and quantify how the baryon cycle plausibly regulates star formation and alters the angular momentum distribution of disk material across the halo mass range where most cosmic star formation occurs.

Formation of double neutron star systems as implied by observations

NASA Astrophysics Data System (ADS)

Beniamini, Paz; Piran, Tsvi

2016-03-01

Double Neutron Stars (DNS) have to survive two supernovae (SNe) and still remain bound. This sets strong limits on the nature of the second collapse in these systems. We consider the masses and orbital parameters of the DNS population and constrain the two distributions of mass ejection and kick velocities directly from observations with no a priori assumptions regarding evolutionary models and/or the types of the SNe involved. We show that there is strong evidence for two distinct types of SNe in these systems, where the second collapse in the majority of the observed systems involved small mass ejection (ΔM ≲ 0.5 M⊙) and a corresponding low-kick velocity (vk ≲ 30 km s-1). This formation scenario is compatible, for example, with an electron-capture SN. Only a minority of the systems have formed via the standard SN scenario involving larger mass ejection of ˜2.2 M⊙ and kick velocities of up to 400 km s-1. Due to the typically small kicks in most DNS (which are reflected by rather low proper motion), we predict that most of these systems reside close to the Galactic disc. In particular, this implies that more NS-NS mergers occur close to the Galactic plane. This may have non-trivial implications to the estimated merger rates of DNS and to the rate of LIGO/VIRGO detections.

Composition of Coronal Mass Ejections

NASA Technical Reports Server (NTRS)

Zurbuchen, T. H.; Weberg, M.; von Steiger, R.; Mewaldt, R. A.; Lepri, S. T.; Antiochos, S. K.

2016-01-01

We analyze the physical origin of plasmas that are ejected from the solar corona. To address this issue, we perform a comprehensive analysis of the elemental composition of interplanetary coronal mass ejections (ICMEs) using recently released elemental composition data for Fe, Mg, Si, S, C, N, Ne, and He as compared to O and H. We find that ICMEs exhibit a systematic abundance increase of elements with first ionization potential (FIP) less than 10 electronvolts, as well as a significant increase of Ne as compared to quasi-stationary solar wind. ICME plasmas have a stronger FIP effect than slow wind, which indicates either that an FIP process is active during the ICME ejection or that a different type of solar plasma is injected into ICMEs. The observed FIP fractionation is largest during times when the Fe ionic charge states are elevated above Q (sub Fe) is greater than 12.0. For ICMEs with elevated charge states, the FIP effect is enhanced by 70 percent over that of the slow wind. We argue that the compositionally hot parts of ICMEs are active region loops that do not normally have access to the heliosphere through the processes that give rise to solar wind. We also discuss the implications of this result for solar energetic particles accelerated during solar eruptions and for the origin of the slow wind itself.

Composition of Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Zurbuchen, T. H.; Weberg, M.; von Steiger, R.; Mewaldt, R. A.; Lepri, S. T.; Antiochos, S. K.

2016-07-01

We analyze the physical origin of plasmas that are ejected from the solar corona. To address this issue, we perform a comprehensive analysis of the elemental composition of interplanetary coronal mass ejections (ICMEs) using recently released elemental composition data for Fe, Mg, Si, S, C, N, Ne, and He as compared to O and H. We find that ICMEs exhibit a systematic abundance increase of elements with first ionization potential (FIP) < 10 eV, as well as a significant increase of Ne as compared to quasi-stationary solar wind. ICME plasmas have a stronger FIP effect than slow wind, which indicates either that an FIP process is active during the ICME ejection or that a different type of solar plasma is injected into ICMEs. The observed FIP fractionation is largest during times when the Fe ionic charge states are elevated above Q Fe > 12.0. For ICMEs with elevated charge states, the FIP effect is enhanced by 70% over that of the slow wind. We argue that the compositionally hot parts of ICMEs are active region loops that do not normally have access to the heliosphere through the processes that give rise to solar wind. We also discuss the implications of this result for solar energetic particles accelerated during solar eruptions and for the origin of the slow wind itself.

Are We Observing Coronal Mass Ejections in OH/IR AGB Stars?

NASA Astrophysics Data System (ADS)

Heiles, Carl

2017-05-01

Solar Coronal Mass Ejections (CMEs) are magnetic electron clouds that are violently ejected by the same magnetic reconnection events that produce Solar flares. CMEs are the major driving source of the hazardous space weather environments near the Earth. In exoplanet systems, the equivalent of Solar wind and CMEs can affect a planet's atmosphere, and in extreme cases can erode it, as probably happened with Mars, or disrupt the cosmic-ray shielding aspect of the planet's magnetic field.We (Jensen et al. 2013SoPh..285...83J, 2016SoPh..291..465J) have developed a new way to observe the electron column density and magnetic field of CMEs, namely to measure the frequency change and Faraday rotation of a spacecraft downlink carrier produced by propagation effects in the plasma. Surprisingly, this can work on other stars if they have the equivalent of the spacecraft carrier, as do OH/IR stars.OH/IR stars are Asymptotic Giant Branch (AGB) stars, which are red giant stars burning He in their final stages of stellar evolution. They have highly convective surfaces and large mass-ejection rates in the form of expanding dense shells of molecular gas and obscuring dust, which were ejected from the star by chaotic turbulent motions and then accelerated by radiation pressure. OH masers reside in these shells, pumped by the IR emission from the dust. The OH masers on the far side of the star (i.e., the positive-velocity masers) are the surrogate for the Solar-case spacecraft signal.The big question: Can we see CMEs in OH/IR stars? We have observed six OH/IR stars with the Arecibo Observatory for a total of about 150 hours over the past 1.5 years. We see changes in OH maser frequency and in the position angle of linear polarization. Both can be produced by electron clouds moving across the line of sight. We will present statistical summaries of the variability and interpret them in terms of CME models.

First High-resolution Spectroscopic Observations by IRIS of a Fast, Helical Prominence Eruption Associated with a Coronal Mass Ejection

NASA Astrophysics Data System (ADS)

Liu, W.; De Pontieu, B.; Okamoto, T. J.; Vial, J. C.; Title, A. M.; Antolin, P.; Berger, T. E.; Uitenbroek, H.

2014-12-01

High-resolution spectroscopic observations of prominence eruptions and associated coronal mass ejections (CMEs) are rare but can provide valuable plasma and energy diagnostics. New opportunities have recently become available with the advent of the Interface Region Imaging Spectrograph (IRIS) mission equipped with high resolution of 0.33-0.4 arcsec in space and 1 km/s in velocity, together with the Hinode Solar Optical Telescope of 0.2 arcsec spatial resolution. We report the first result of joint IRIS-Hinode observations of a spectacular prominence eruption occurring on 2014-May-09. IRIS detected a maximum redshift of 450 km/s, which, combined with the plane-of-sky speed of 800 km/s, gives a large velocity vector of 920 km/s at 30 degrees from the sky plane. This direction agrees with the source location at 30 degrees behind the limb observed by STEREO-A and indicates a nearly vertical ejection. We found two branches of redshifts separated by 200 km/s appearing in all strong lines at chromospheric to transition-region temperatures, including Mg II k/h, C II, and Si IV, suggesting a hollow, rather than solid, cone in the velocity space of the ejected material. Opposite blue- and redshifts on the two sides of the prominence exhibit corkscrew variations both in space and time, suggestive of unwinding rotations of a left-handed helical flux rope. Some erupted material returns as nearly streamline flows, exhibiting distinctly narrow line widths (~10 km/s), about 50% of those of the nearby coronal rain at the apexes of coronal loops, where the rain material is initially formed out of cooling condensation. We estimate the mass and kinetic energy of the ejected and returning material and compare them with those of the associated CME. We will discuss the implications of these observations for CME initiation mechanisms.

Coronal mass ejection and solar flare initiation processes without appreciable

NASA Astrophysics Data System (ADS)

Veselovsky, I.

TRACE and SOHO/EIT movies clearly show the cases of the coronal mass ejection and solar flare initiations without noticeable large-scale topology modifications in observed features. Instead of this, the appearance of new intermediate scales is often omnipresent in the erupting region structures when the overall configuration is preserved. Examples of this kind are presented and discussed in the light of the existing magnetic field reconnection paradigms. It is demonstrated that spurious large-scale reconnections and detachments are often produced due to the projection effects in poorly resolved images of twisted loops and sheared arcades especially when deformed parts of them are underexposed and not seen in the images only because of this reason. Other parts, which are normally exposed or overexposed, can make the illusion of "islands" or detached elements in these situations though in reality they preserve the initial magnetic connectivity. Spurious "islands" of this kind could be wrongly interpreted as signatures of topological transitions in the large-scale magnetic fields in many instances described in the vast literature in the past based mainly on fuzzy YOHKOH images, which resulted in the myth about universal solar flare models and the scenario of detached magnetic island formations with new null points in the large scale magnetic field. The better visualization with higher resolution and sensitivity limits allowed to clarify this confusion and to avoid this unjustified interpretation. It is concluded that topological changes obviously can happen in the coronal magnetic fields, but these changes are not always necessary ingredients at least of all coronal mass ejections and solar flares. The scenario of the magnetic field opening is not universal for all ejections. Otherwise, expanding ejections with closed magnetic configurations can be produced by the fast E cross B drifts in strong inductive electric fields, which appear due to the emergence of the new magnetic flux. Corresponding theoretical models are presented and discussed.

Ejection of a rear facing, golf cart passenger.

PubMed

Schau, Kyle; Masory, Oren

2013-10-01

The following report details the findings of a series of experiments and simulations performed on a commercially available, shuttle style golf cart during several maneuvers involving rapid accelerations of the vehicle. It is determined that the current set of passive restraints on these types of golf carts are not adequate in preventing ejection of a rear facing passenger during rapid accelerations in the forward and lateral directions. Experimental data and simulations show that a hip restraint must be a minimum of 13 in. above the seat in order to secure a rear facing passenger during sharp turns, compared to the current restraint height of 5 in. Furthermore, it is determined that a restraint directly in front of the rear facing passenger is necessary to prevent ejection. In addressing these issues, golf cart manufacturers could greatly reduce the likelihood of injury due to ejection of a rear facing, golf cart passenger. Copyright © 2013 Elsevier Ltd. All rights reserved.

A study of mass loss from the mid-ultraviolet spectrum of Alpha Cygni /A2 Ia/, Beta Orionis /B8 Ia/, and Eta Leonis /A0 Ib/

NASA Technical Reports Server (NTRS)

Lamers, H. J. G. L. M.; Stalio, R.; Kondo, Y.

1978-01-01

Results are presented for a study of mass loss from A and late-B supergiants based on high-resolution mid-UV spectra obtained with the echelle spectrograph of the Balloon-borne Ultraviolet Stellar Spectrometer. Spectra of Alpha Cyg, Beta Ori, Eta Leo, and Alpha Lyr are compared in selected wavelength regions; particular attention is given to previous observations of each star, the Mg II and Fe II resonance lines, lines due to other ions, and evidence for mass ejection. The results indicate that mass loss from late-B and A supergiants is variable, that a considerable fraction of envelope material is ejected in 'puffs', and that the puffs may be due to photospheric instabilities. A mass-loss rate of about 1 hundred-millionth of a solar mass per year is derived for Alpha Cyg and shown to be two orders of magnitude smaller than the value determined from the observed IR excess. This discrepancy is attributed to excess ionization in the envelope.

Thermosphere Global Time Response to Geomagnetic Storms Caused by Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Oliveira, D. M.; Zesta, E.; Schuck, P. W.; Sutton, E. K.

2017-10-01

We investigate, for the first time with a spatial superposed epoch analysis study, the thermosphere global time response to 159 geomagnetic storms caused by coronal mass ejections (CMEs) observed in the solar wind at Earth's orbit during the period of September 2001 to September 2011. The thermosphere neutral mass density is obtained from the CHAMP (CHAllenge Mini-Satellite Payload) and GRACE (Gravity Recovery Climate Experiment) spacecraft. All density measurements are intercalibrated against densities computed by the Jacchia-Bowman 2008 empirical model under the regime of very low geomagnetic activity. We explore both the effects of the pre-CME shock impact on the thermosphere and of the storm main phase onset by taking their times of occurrence as zero epoch times (CME impact and interplanetary magnetic field Bz southward turning) for each storm. We find that the shock impact produces quick and transient responses at the two high-latitude regions with minimal propagation toward lower latitudes. In both cases, thermosphere is heated in very high latitude regions within several minutes. The Bz southward turning of the storm onset has a fast heating manifestation at the two high-latitude regions, and it takes approximately 3 h for that heating to propagate down to equatorial latitudes and to globalize in the thermosphere. This heating propagation is presumably accomplished, at least in part, with traveling atmospheric disturbances and complex meridional wind structures. Current models use longer lag times in computing thermosphere density dynamics during storms. Our results suggest that the thermosphere response time scales are shorter and should be accordingly adjusted in thermospheric empirical models.

The role of Mab as a source for the μ ring of Uranus

NASA Astrophysics Data System (ADS)

Sfair, R.; Giuliatti Winter, S. M.

2012-07-01

Context. We previously analysed how the solar radiation force combined with the planetary oblateness changes the orbital evolution of a sample of dust particles located at the secondary ring system of Uranus. Both effects combined with the gravitational perturbations of the close satellites lead to the depletion of these dust particles through collisions on the surfaces of these satellites on a timescale of hundreds of years. Aims: In this work we investigate if the impacts of interplanetary dust particles (IDPs) onto Mab's surface can produce sufficient particles to replenish the μ ring population. Methods: We first analysed through numerical simulations the evolution of a sample of particles ejected from the surface of Mab and computed the lifetime of the grains when the effects of the solar radiation pressure and the planetary oblateness are taken into account. Then we estimated the mass production rate due to the impacts of IDPs following a previously established algorithm, and used this value to determine the time necessary to accumulate an amount of particles comparable with the mass of the μ ring. Results: Based on an estimate of the flux of interplanetary particles and on the surface properties of Mab it is expected that the satellite supplies material to the ring at a rate of ~3 g/s. Meanwhile, our numerical model showed that the ejected particles are removed from the system through collisions with the satellite, and the mean lifetime of the grains may vary from 320 to 1500 years, depending on the radius of the particle. Conclusions: The time necessary to accumulate the mass of the μ ring via ejection from Mab is much shorter than the mean lifetime of the particles, and a stationary regime is not reached. If the ring is kept in a steady state, other effects such as the electromagnetic force and/or the existence of additional bodies may play a significant role in the dust balance, but the current lack of information about the environment renders modelling these effects unfeasible.

A dynamic magnetic tension force as the cause of failed solar eruptions

DOE Data Explorer

Myers, Clayton E. [Princeton Univ., NJ (United States). Dept. of Astrophysical Sciences; Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); ] (ORCID:0000000345398406); Yamada, Maasaki [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000349961649); Ji, Hantao [Princeton Univ., NJ (United States). Dept. of Astrophysical Sciences; Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Laboratory for Space Environment and Physical Sciences, Harbin Institute of Technology, Harbin, Heilongjiang 150001, China] (ORCID:0000000196009963); Yoo, Jongsoo [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000338811995); Fox, William [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:000000016289858X); Jara-Almonte, Jonathan [Princeton Univ., NJ (United States). Dept. of Astrophysical Sciences; Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); ] (ORCID:0000000307606198); Savcheva, Antonia [Harvard†“ Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA] (ORCID:000000025598046X); DeLuca, Edward E. [Harvard†“ Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA] (ORCID:0000000174162895)

2015-12-11

Coronal mass ejections are solar eruptions driven by a sudden release of magnetic energy stored in the Sun’s corona. In many cases, this magnetic energy is stored in long-lived, arched structures called magnetic flux ropes. When a flux rope destabilizes, it can either erupt and produce a coronal mass ejection or fail and collapse back towards the Sun. The prevailing belief is that the outcome of a given event is determined by a magnetohydrodynamic force imbalance called the torus instability. This belief is challenged, however, by observations indicating that torus-unstable flux ropes sometimes fail to erupt. This contradiction has not yet been resolved because of a lack of coronal magnetic field measurements and the limitations of idealized numerical modelling. Here we report the results of a laboratory experiment that reveal a previously unknown eruption criterion below which torus-unstable flux ropes fail to erupt. We find that such ‘failed torus’ events occur when the guide magnetic field (that is, the ambient field that runs toroidally along the flux rope) is strong enough to prevent the flux rope from kinking. Under these conditions, the guide field interacts with electric currents in the flux rope to produce a dynamic toroidal field tension force that halts the eruption. This magnetic tension force is missing from existing eruption models, which is why such models cannot explain or predict failed torus events.

MODELING THE INITIATION OF THE 2006 DECEMBER 13 CORONAL MASS EJECTION IN AR 10930: THE STRUCTURE AND DYNAMICS OF THE ERUPTING FLUX ROPE

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

Fan, Yuhong, E-mail: yfan@ucar.edu

2016-06-20

We carry out a 3D magnetohydrodynamic simulation to model the initiation of the coronal mass ejection (CME) on 2006 December 13 in the emerging δ -sunspot active region NOAA 10930. The setup of the simulation is similar to a previous simulation by Fan, but with a significantly widened simulation domain to accommodate the wide CME. The simulation shows that the CME can result from the emergence of a east–west oriented twisted flux rope whose positive, following emerging pole corresponds to the observed positive rotating sunspot emerging against the southern edge of the dominant pre-existing negative sunspot. The erupting flux ropemore » in the simulation accelerates to a terminal speed that exceeds 1500 km s{sup −1} and undergoes a counter-clockwise rotation of nearly 180° such that its front and flanks all exhibit southward directed magnetic fields, explaining the observed southward magnetic field in the magnetic cloud impacting the Earth. With continued driving of flux emergence, the source region coronal magnetic field also shows the reformation of a coronal flux rope underlying the flare current sheet of the erupting flux rope, ready for a second eruption. This may explain the build up for another X-class eruptive flare that occurred the following day from the same region.« less

Iron Charge Distribution as an Identifier of Interplanetary Coronal Mass Ejections

NASA Technical Reports Server (NTRS)

Lepri, S. T.; Zurbuchen, T. H.; Fisk, L. A.; Richardson, I. G.; Cane, H. V.; Gloeckler, G.

2001-01-01

We present solar wind Fe charge state data measured on the Advanced Composition Explorer (ACE) from early 1998 to the middle of 2000. Average Fe charge states in the solar wind are typically around 9 to 11. However, deviations from these average charge states occur, including intervals with a large fraction of Fe(sup greater or = 16+) which are consistently associated with interplanetary coronal mass ejections (ICMEs). By studying the Fe charge state distribution we are able to extract coronal electron temperatures often exceeding 2 x 10(exp 6) kelvins. We also discuss the temporal trends of these events, indicating the more frequent appearance of periods with high Fe charge states as solar activity increases.

Plasma Heating During Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Murphy, N. A.; Shen, C.; Rimple, R.; Raymond, J. C.

2016-12-01

Several recent observational analyses have shown that plasma heating enters into the energy budget of coronal mass ejections (CMEs) at about the same order of magnitude as the kinetic energy. The ultimate source of the heating is the magnetic field, but the mechanisms by which magnetic energy is converted to thermal energy are poorly understood. We will review observational evidence for CME heating and discuss candidate mechanisms that may be responsible for the heating. We will discuss the Python implementation of a non-equilibrium ionization model and its application to CME plasma, and report on progress on modeling three events where the Ultraviolet Coronagraph Spectrometer (UVCS) on the Solar and Heliospheric Observatory (SOHO) observed the same ejecta at multiple heights.

An Investigation of the Large Scale Evolution and Topology of Coronal Mass Ejections in the Solar Wind

NASA Technical Reports Server (NTRS)

Riley, Peter

2000-01-01

This investigation is concerned with the large-scale evolution and topology of coronal mass ejections (CMEs) in the solar wind. During this reporting period we have focused on several aspects of CME properties, their identification and their evolution in the solar wind. The work included both analysis of Ulysses and ACE observations as well as fluid and magnetohydrodynamic simulations. In addition, we analyzed a series of "density holes" observed in the solar wind, that bear many similarities with CMEs. Finally, this work was communicated to the scientific community at three meetings and has led to three scientific papers that are in various stages of review.

Investigating the surface brightness profiles, ejected mass and speed from the outburst events of comet 67P/Churyumov-Gerasmenko

NASA Astrophysics Data System (ADS)

Lin, Zhong-Yi; Vincent, Jean-Baptiste; A'Hearn, Mike; Lara, Luisa; Knollenberg, Joerg; Ip, Wing-Huen; Osiris Team

2016-04-01

The OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) WAC and NAC camera onboard the ESA Rosetta spacecraft orbiting 67P/Churyumov-Gersimenko has captured a lot of outbursts since July, 2015. Most of their source regions were located at southern hemisphere of comet C-G. Including the March- and perihelion-outbursts, the detected events show a variety of morphological features (i.e. broad fan, collimated jet and so on). In this work, we investigate these events and characterize the physical properties, including the surface brightness profiles, ejected mass and speed if there were two or more images acquired by the same filter during the outburst timeframe.

A moderately precise dynamical age for the Homunculus of Eta Carinae based on 13 years of HST imaging

NASA Astrophysics Data System (ADS)

Smith, Nathan

2017-11-01

The Hubble Space Telescope archive contains a large collection of images of η Carinae, and this paper analyses those most suitable for measuring its expanding Homunculus Nebula. Multiple intensity tracings through the Homunculus reveal the fractional increase in the overall size of the nebula; this avoids registration uncertainty, mitigates brightness fluctuations, and is independent of previous methods. Combining a 13 yr baseline of Wide Field Planetary Camera 2 images in the F631N filter, with a 4 yr baseline of Advanced Camera for Surveys/High Resolution Channel images in the F550M filter, yields an ejection date (assuming linear motion) of 1847.1 (±0.8 yr). This result improves the precision, but is in excellent agreement with the previous study by Morse et al., that used a shorter time baseline and a different analysis method. This more precise date is inconsistent with ejection during a periastron passage of the eccentric binary. Ejection occurred well into the main plateau of the Great Eruption, and not during the brief peaks in 1843 and 1838. The age uncertainty is dominated by a real spread in ages of various knots, and by some irregular brightness fluctuations. Several knots appear to have been ejected decades before or after the mean date, implying a complicated history of mass-loss episodes outside the main bright phase of the eruption. The extended history of mass ejection may have been largely erased by the passage of a shock through clumpy ejecta, as most material was swept into a thin shell with nearly uniform apparent age.

Common-envelope ejection in massive binary stars. Implications for the progenitors of GW150914 and GW151226

NASA Astrophysics Data System (ADS)

Kruckow, M. U.; Tauris, T. M.; Langer, N.; Szécsi, D.; Marchant, P.; Podsiadlowski, Ph.

2016-11-01

Context. The recently detected gravitational wave signals (GW150914 and GW151226) of the merger event of a pair of relatively massive stellar-mass black holes (BHs) calls for an investigation of the formation of such progenitor systems in general. Aims: We analyse the common-envelope (CE) stage of the traditional formation channel in binaries where the first-formed compact object undergoes an in-spiral inside the envelope of its evolved companion star and ejects the envelope in this process. Methods: We calculated envelope binding energies of donor stars with initial masses between 4 and 115M⊙ for metallicities of Z = ZMilky Way ≃ Z⊙/ 2 and Z = Z⊙/ 50, and derived minimum masses of in-spiralling objects needed to eject these envelopes. Results: In addition to producing double white dwarf and double neutron star binaries, CE evolution may also produce massive BH-BH systems with individual BH component masses of up to 50 - 60M⊙, in particular for donor stars evolved to giants beyond the Hertzsprung gap. However, the physics of envelope ejection of massive stars remains uncertain. We discuss the applicability of the energy-budget formalism, the location of the bifurcation point, the recombination energy, and the accretion energy during in-spiral as possible energy sources, and also comment on the effect of inflated helium cores. Conclusions: Massive stars in a wide range of metallicities and with initial masses of up to at least 115M⊙ may shed their envelopes and survive CE evolution, depending on their initial orbital parameters, similarly to the situation for intermediate- and low-mass stars with degenerate cores. In addition to being dependent on stellar radius, the envelope binding energies and λ-values also depend on the applied convective core-overshooting parameter, whereas these structure parameters are basically independent of metallicity for stars with initial masses below 60M⊙. Metal-rich stars ≳60M⊙ become luminous blue variables and do not evolve to reach the red giant stage. We conclude that based on stellar structure calculations, and in the view of the usual simple energy budget analysis, events like GW150914 and GW151226 might be produced by the CE channel. Calculations of post-CE orbital separations, however, and thus the estimated LIGO detection rates, remain highly uncertain.

Phaethon Near Earth

NASA Astrophysics Data System (ADS)

Jewitt, David

2017-08-01

Planet-crossing asteroid (3200) Phaethon, source of the Geminid meteoroid stream, will pass close to Earth in December 2017. Observations with HST are proposed to image debris ejected from this object at 1 AU heliocentric distance, to estimate the ejection velocities as the Earth passes through the orbit plane, and to estimate the dust production rate for comparison with the rates needed to sustain the Geminid stream in steady-state. These measurements will help determine the mechanism behind the ejection of the Geminids, a long-standing puzzle. While the release of micron-sized particles (probably by thermal fracture) has been recorded at Phaethon's perihelion (0.14 AU), mass loss has never been detected otherwise, raising the puzzle of the ejection mechanism and duration. The close approach (0.07 AU) on December 17 gives a once-in-a-lifetime opportunity to observe Phaethon at high sensitivity with a resolution of a few kilometers.

Exploring the Role of Overlying Fields and Flare Ribbons in CME Speeds

NASA Astrophysics Data System (ADS)

Deng, M.; Welsch, B. T.

2013-12-01

The standard model of eruptive, two-ribbon flares involves reconnection of overlying magnetic fields beneath a rising ejection. Numerous observers have reported evidence linking this reconnection, indicated by photospheric flux swept out by flare ribbons, to coronal mass ejection (CME) acceleration. This acceleration might be caused by reconnected fields that wrap around the ejection producing an increased outward "hoop force." Other observations have linked stronger overlying fields, measured by the power-law index of the fitted decay rate of field strengths overlying eruption sites, to slower CME speeds. This might be caused by greater downward magnetic tension in stronger overlying fields. So overlying fields might both help and hinder the acceleration of CMEs: reconnection that converts overlying fields into flux winding about the ejection might help, but unreconnected overlying fields might hurt. Here, we investigate the roles of both ribbon fluxes and the decay rates of overlying fields in a set of eruptive events.

The Double-Peaked SN 2013ge: A Type Ib/c Sn with an Asymmetric Mass Ejection or an Extended Progenitor Envelope

NASA Technical Reports Server (NTRS)

Drout, M. R.; Milisavjlevic, D.; Parrent, J.; Margutti, R.; Kamble, A.; Soderberg, A.M.; Challis, P.; Chornock, P.; Fong, W.; Frank, S.;

Investigation of geomagnetic induced current at high latitude during the storm-time variation

NASA Astrophysics Data System (ADS)

Falayi, E. O.; Ogunmodimu, O.; Bolaji, O. S.; Ayanda, J. D.; Ojoniyi, O. S.

2017-06-01

During the geomagnetic disturbances, the geomagnetically induced current (GIC) are influenced by the geoelectric field flowing in conductive Earth. In this paper, we studied the variability of GICs, the time derivatives of the geomagnetic field (dB/dt), geomagnetic indices: Symmetric disturbance field in H (SYM-H) index, AU (eastward electrojet) and AL (westward electrojet) indices, Interplanetary parameters such as solar wind speed (v), and interplanetary magnetic field (Bz) during the geomagnetic storms on 31 March 2001, 21 October 2001, 6 November 2001, 29 October 2003, 31 October 2003 and 9 November 2004 with high solar wind speed due to a coronal mass ejection. Wavelet spectrum based approach was employed to analyze the GIC time series in a sequence of time scales of one to twenty four hours. It was observed that there are more concentration of power between the 14-24 h on 31 March 2001, 17-24 h on 21 October 2001, 1-7 h on 6 November 2001, two peaks were observed between 5-8 h and 21-24 h on 29 October 2003, 1-3 h on 31 October 2003 and 18-22 h on 9 November 2004. Bootstrap method was used to obtain regression correlations between the time derivative of the geomagnetic field (dB/dt) and the observed values of the geomagnetic induced current on 31 March 2001, 21 October 2001, 6 November 2001, 29 October 2003, 31 October 2003 and 9 November 2004 which shows a distributed cluster of correlation coefficients at around r = -0.567, -0.717, -0.477, -0.419, -0.210 and r = -0.488 respectively. We observed that high energy wavelet coefficient correlated well with bootstrap correlation, while low energy wavelet coefficient gives low bootstrap correlation. It was noticed that the geomagnetic storm has a influence on GIC and geomagnetic field derivatives (dB/dt). This might be ascribed to the coronal mass ejection with solar wind due to particle acceleration processes in the solar atmosphere.

A System Scale Theory for Fast Magnetic Reconnection

NASA Astrophysics Data System (ADS)

Knoll, D.; Chacon, L.; Lapenta, G.

2005-12-01

Magnetic reconnection is at the root of explosive phenomena such as solar flares, coronal mass ejections, plasmoid ejection from earth's magnetotail and major disruptions in magnetic fusion energy experiments. Plasmas in all the above mentioned cases are known to have negligible electric resistivity. This small resistivity can not explain the reconnection time scales observed in nature, when using the resistive MHD model. Recently much progress has been made considering the Hall MHD model. Hall physics has been shown to facility fast reconnection when the magnetic field shear scale length is in the order of the ion inertial length. However, in many systems of interest the initial scale lengths of the problem can not justify the use of Hall MHD. Thus a successful system scale theory must involve a current sheet thinning mechanism which brings the relevant scales down to the Hall scales. In this presentation we give examples of how naturally occurring hydrodynamic flows can provide such current sheet thinning [1,2,3] and where these occur in solar [4] and magnetosphere application [5]. We also discuss the primary obstacle for such flow to drive current sheet thinning, the build up of magnetic pressure, and how Hall MHD may overcome this obstacle. [1] Knoll and Brackbill, Phys. Plasmas, vol. 9, 2002 [2] Knoll and Chacon, PRL, vol. 88, 2002 [3] Knoll and Chacon, Phys. Plasmas, 2005 (submitted) [4] Lapenta and Knoll, ApJ, vol. 624, 2005 [5] Brackbill and Knoll, PRL, vol. 86, 2001

Hydrodynamic models for novae with ejecta rich in oxygen, neon and magnesium

NASA Technical Reports Server (NTRS)

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

1985-01-01

The characteristics of a new class of novae are identified and explained. This class consists of those objects that have been observed to eject material rich in oxygen, neon, magnesium, and aluminum at high velocities. We propose that for this class of novae the outburst is occurring not on a carbon-oxygen white dwarf but on an oxygen-neon-magnesium white dwarf which has evolved from a star which had a main sequence mass of approx. 8 solar masses to approx. 12 solar masses. An outburst was simulated by evolving 1.25 solar mass white dwarfs accreting hydrogen rich material at various rates. The effective enrichment of the envelope by ONeMg material from the core is simulated by enhancing oxygen in the accreted layers. The resulting evolutionary sequences can eject the entire accreted envelope plus core material at high velocities. They can also become super-Eddington at maximum bolometric luminosity. The expected frequency of such events (approx. 1/4) is in good agreement with the observed numbers of these novae.

The rate of planet formation and the solar system's small bodies

NASA Technical Reports Server (NTRS)

Safronov, Viktor S.

1991-01-01

The evolution of random velocities and the mass distribution of preplanetary body at the early stage of accumulation are currently under review. Arguments were presented for and against the view of an extremely rapid, runaway growth of the largest bodies at this stage with parameter values of Theta approximately greater than 10(exp 3). Difficulties are encountered assuming such a large Theta: (1) bodies of the Jovian zone penetrate the asteroid zone too late and do not have time to hinder the formation of a normal-sized planet in the asteroidal zone and thereby remove a significant portion of the mass of solid matter and (2) Uranus and Neptune cannot eject bodies from the solar system into the cometary cloud. Therefore, the values Theta less than 10(exp 2) appear to be preferable.

A survey of mass-loss effects in early-type stars

NASA Technical Reports Server (NTRS)

Snow, T. P., Jr.

1976-01-01

Intermediate-resolution data obtained with the Copernicus satellite are surveyed in order to define the region in the H-R diagram where mass loss occurs. The survey includes 40 stars, providing good coverage of supergiants from O4 to A2 and main-sequence stars from O4 to B7 as well as spotty coverage of late O giants and intermediate to late B stars. The spectral transitions examined are primarily resonance lines of ions of abundant elements plus some lines arising from excited states (e.g., C III at 1175.7 A and Si IV at 1122.5 A). Observed P Cygni profiles are discussed along with interesting features of some individual profiles. The data are shown to indicate that mass-loss effects occur over a wide portion of the H-R diagram, that mass ejection generally occurs when the holometric magnitude is greater than -6.0, and that the mass-ejection rate is usually high enough to produce P Cygni profile whenever the N V feature at 1240 A is present in a spectrum.

Modeling UV Radiation Feedback from Massive Stars. II. Dispersal of Star-forming Giant Molecular Clouds by Photoionization and Radiation Pressure

NASA Astrophysics Data System (ADS)

Kim, Jeong-Gyu; Kim, Woong-Tae; Ostriker, Eve C.

2018-05-01

UV radiation feedback from young massive stars plays a key role in the evolution of giant molecular clouds (GMCs) by photoevaporating and ejecting the surrounding gas. We conduct a suite of radiation hydrodynamic simulations of star cluster formation in marginally bound, turbulent GMCs, focusing on the effects of photoionization and radiation pressure on regulating the net star formation efficiency (SFE) and cloud lifetime. We find that the net SFE depends primarily on the initial gas surface density, Σ0, such that the SFE increases from 4% to 51% as Σ0 increases from 13 to 1300 {M}ȯ {pc}}-2. Cloud destruction occurs within 2–10 Myr after the onset of radiation feedback, or within 0.6–4.1 freefall times (increasing with Σ0). Photoevaporation dominates the mass loss in massive, low surface density clouds, but because most photons are absorbed in an ionization-bounded Strömgren volume, the photoevaporated gas fraction is proportional to the square root of the SFE. The measured momentum injection due to thermal and radiation pressure forces is proportional to {{{Σ }}}0-0.74, and the ejection of neutrals substantially contributes to the disruption of low mass and/or high surface density clouds. We present semi-analytic models for cloud dispersal mediated by photoevaporation and by dynamical mass ejection, and show that the predicted net SFE and mass loss efficiencies are consistent with the results of our numerical simulations.

Mediterranean diet score and left ventricular structure and function: the Multi-Ethnic Study of Atherosclerosis12

PubMed Central

Levitan, Emily B; Ahmed, Ali; Arnett, Donna K; Polak, Joseph F; Hundley, W Gregory; Bluemke, David A; Heckbert, Susan R; Jacobs, David R; Nettleton, Jennifer A

2016-01-01

Background: Data are limited on the relation between dietary patterns and left ventricular (LV) structure and function. Objective: We examined cross-sectional associations of a diet-score assessment of a Mediterranean dietary pattern with LV mass, volume, mass-to-volume ratio, stroke volume, and ejection fraction. Design: We measured LV variables with the use of cardiac MRI in 4497 participants in the Multi-Ethnic Study of Atherosclerosis study who were aged 45–84 y and without clinical cardiovascular disease. We calculated a Mediterranean diet score from intakes of fruit, vegetables, nuts, legumes, whole grains, fish, red meat, the monounsaturated fat:saturated fat ratio, and alcohol that were self-reported with the use of a food-frequency questionnaire. We used linear regression with adjustment for body size, physical activity, and cardiovascular disease risk factors to model associations and assess the shape of these associations (linear or quadratic). Results: The Mediterranean diet score had a slight U-shaped association with LV mass (adjusted means: 146, 145, 146, and 147 g across quartiles of diet score, respectively; P-quadratic trend = 0.04). The score was linearly associated with LV volume, stroke volume, and ejection fraction: for each +1-U difference in score, LV volume was 0.4 mL higher (95% CI: 0.0, 0.8 mL higher), the stroke volume was 0.5 mL higher (95% CI: 0.2, 0.8 mL higher), and the ejection fraction was 0.2 percentage points higher (95% CI: 0.1, 0.3 percentage points higher). The score was not associated with the mass-to-volume ratio. Conclusions: A higher Mediterranean diet score is cross-sectionally associated with a higher LV mass, which is balanced by a higher LV volume as well as a higher ejection fraction and stroke volume. Participants in this healthy, multiethnic sample whose dietary patterns most closely conformed to a Mediterranean-type pattern had a modestly better LV structure and function than did participants with less–Mediterranean-like dietary patterns. This trial was registered at clinicaltrials.gov as NCT00005487. PMID:27488238

Mediterranean diet score and left ventricular structure and function: the Multi-Ethnic Study of Atherosclerosis.

PubMed

Levitan, Emily B; Ahmed, Ali; Arnett, Donna K; Polak, Joseph F; Hundley, W Gregory; Bluemke, David A; Heckbert, Susan R; Jacobs, David R; Nettleton, Jennifer A

2016-09-01

Data are limited on the relation between dietary patterns and left ventricular (LV) structure and function. We examined cross-sectional associations of a diet-score assessment of a Mediterranean dietary pattern with LV mass, volume, mass-to-volume ratio, stroke volume, and ejection fraction. We measured LV variables with the use of cardiac MRI in 4497 participants in the Multi-Ethnic Study of Atherosclerosis study who were aged 45-84 y and without clinical cardiovascular disease. We calculated a Mediterranean diet score from intakes of fruit, vegetables, nuts, legumes, whole grains, fish, red meat, the monounsaturated fat:saturated fat ratio, and alcohol that were self-reported with the use of a food-frequency questionnaire. We used linear regression with adjustment for body size, physical activity, and cardiovascular disease risk factors to model associations and assess the shape of these associations (linear or quadratic). The Mediterranean diet score had a slight U-shaped association with LV mass (adjusted means: 146, 145, 146, and 147 g across quartiles of diet score, respectively; P-quadratic trend = 0.04). The score was linearly associated with LV volume, stroke volume, and ejection fraction: for each +1-U difference in score, LV volume was 0.4 mL higher (95% CI: 0.0, 0.8 mL higher), the stroke volume was 0.5 mL higher (95% CI: 0.2, 0.8 mL higher), and the ejection fraction was 0.2 percentage points higher (95% CI: 0.1, 0.3 percentage points higher). The score was not associated with the mass-to-volume ratio. A higher Mediterranean diet score is cross-sectionally associated with a higher LV mass, which is balanced by a higher LV volume as well as a higher ejection fraction and stroke volume. Participants in this healthy, multiethnic sample whose dietary patterns most closely conformed to a Mediterranean-type pattern had a modestly better LV structure and function than did participants with less-Mediterranean-like dietary patterns. This trial was registered at clinicaltrials.gov as NCT00005487. © 2016 American Society for Nutrition.

Second shock ejecta measurements with an explosively driven two-shockwave drive

NASA Astrophysics Data System (ADS)

Buttler, W. T.; Oró, D. M.; Olson, R. T.; Cherne, F. J.; Hammerberg, J. E.; Hixson, R. S.; Monfared, S. K.; Pack, C. L.; Rigg, P. A.; Stone, J. B.; Terrones, G.

2014-09-01

We develop and apply an explosively driven two-shockwave tool in material damage experiments on Sn. The two shockwave tool allows the variation of the first shockwave amplitude over range 18.5 to 26.4 GPa, with a time interval variation between the first and second shock of 5 to 7 μs. Simulations imply that the second shock amplitude can be varied as well and we briefly describe how to achieve such a variation. Our interest is to measure ejecta masses from twice shocked metals. In our application of the two-shockwave tool, we observed second shock ejected areal masses of about 4 ± 1 mg/cm2, a value we attribute to unstable Richtmyer-Meshkov impulse phenomena. We also observed an additional mass ejection process caused by the abrupt recompression of the local spallation or cavitation of the twice shocked Sn.

Highly supersonic bipolar mass ejection from a red giant OH/IR source - OH 0739 - 14

NASA Technical Reports Server (NTRS)

Cohen, M.; Dopita, M. A.; Schwartz, R. D.; Tielens, A. G. G. M.

1985-01-01

From long-slit spectrophotometry of the bipolar nebula associated with the unusual OH source, OH 0739 - 14, the presence of a blue companion to the M9 III central star was shown and a Herbig-Haro-like knot beyond each nebular lobe was discovered. From differential colors of the lobes and from radial velocities of these knots it was demonstrated that the system inclines its northern lobe in the forward direction. It was also shown that the nebulous knots are shocks being driven into an extensive circumstellar envelope, and that this material is very overabundant in nitrogen, suggesting that it is matter lost from a star of mass greater than 3 solar masses. A model of biconical ejection from a central binary is consistent with the OH observations, and a possible relation of OH 0739 - 14 to the symbiotic stars and to bipolar planetary nebulae is suggested.

Interstellar Object ’Oumuamua as an Extinct Fragment of an Ejected Cometary Planetesimal

NASA Astrophysics Data System (ADS)

Raymond, Sean N.; Armitage, Philip J.; Veras, Dimitri

2018-03-01

’Oumuamua was discovered passing through our solar system on a hyperbolic orbit. It presents an apparent contradiction, with colors similar to those of volatile-rich solar system bodies but with no visible outgassing or activity during its close approach to the Sun. Here, we show that this contradiction can be explained by the dynamics of planetesimal ejection by giant planets. We propose that ’Oumuamua is an extinct fragment of a comet-like planetesimal born a planet-forming disk that also formed Neptune- to Jupiter-mass giant planets. On its pathway to ejection ’Oumuamua’s parent body underwent a close encounter with a giant planet and was tidally disrupted into small pieces, similar to comet Shoemaker–Levy 9’s disruption after passing close to Jupiter. We use dynamical simulations to show that 0.1%–1% of cometary planetesimals undergo disruptive encounters prior to ejection. Rocky asteroidal planetesimals are unlikely to disrupt due to their higher densities. After disruption, the bulk of fragments undergo enough close passages to their host stars to lose their surface volatiles and become extinct. Planetesimal fragments such as ’Oumuamua contain little of the mass in the population of interstellar objects but dominate by number. Our model makes predictions that will be tested in the coming decade by the Large Synoptic Survey Telescope.

Onset of the Magnetic Explosion in Filament-Eruption Flares and Coronal Mass Ejections: Single-Bipole Events

NASA Technical Reports Server (NTRS)

Moore, Ron L.; Sterling, Alphonse C.

2000-01-01

We present three-dimensional sketches of die magnetic field before and during filament eruptions in flares and coronal mass ejections. Before the eruption, the overall magnetic field is a closed bipole in which the core field (the field rooted along the bipole's neutral line in the photospheric magnetic flux) is strongly sheared and has oppositely curved "elbows" that bulge out from the opposite ends of the neutral line. This core-field sigmoid runs under and is pressed down in the middle by the rest of the field in the bipole, the less-sheared envelope field rooted outside the core field (as in the model of Antiochos, Dahlburg, & Klimchuk. A filament of chromospheric-temperature plasma is often held in the core field over the neutral line. In a filament eruption, the core field undergoes an explosive eruption, the frozen-in filament plasma providing a visible tracer of the erupting field. The core-field explosion may be either confined (as in some flares) or ejective (as in CMEs that begin together with the onset of a long-duration two-ribbon flare). We present examples of each of these two kind of events as observed in sequences of coronal X-ray images from the Yohkoh SXT, and consider (1) how the explosion begins, and (2) whether confined eruptions begin in basically the same way as ejective eruptions.

An ice-cream cone model for coronal mass ejections

NASA Astrophysics Data System (ADS)

Xue, X. H.; Wang, C. B.; Dou, X. K.

2005-08-01

In this study, we use an ice-cream cone model to analyze the geometrical and kinematical properties of the coronal mass ejections (CMEs). Assuming that in the early phase CMEs propagate with near-constant speed and angular width, some useful properties of CMEs, namely the radial speed (v), the angular width (α), and the location at the heliosphere, can be obtained considering the geometrical shapes of a CME as an ice-cream cone. This model is improved by (1) using an ice-cream cone to show the near real configuration of a CME, (2) determining the radial speed via fitting the projected speeds calculated from the height-time relation in different azimuthal angles, (3) not only applying to halo CMEs but also applying to nonhalo CMEs.

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

Shields, G. A.; Bonning, E. W., E-mail: shields@astro.as.utexas.edu, E-mail: erin.bonning@questu.ca

Recent results indicate that the compact lenticular galaxy NGC 1277 in the Perseus Cluster contains a black hole of mass {approx}10{sup 10} M{sub Sun }. This far exceeds the expected mass of the central black hole in a galaxy of the modest dimensions of NGC 1277. We suggest that this giant black hole was ejected from the nearby giant galaxy NGC 1275 and subsequently captured by NGC 1277. The ejection was the result of gravitational radiation recoil when two large black holes merged following the merger of two giant ellipticals that helped to form NGC 1275. The black hole wanderedmore » in the cluster core until it was captured in a close encounter with NGC 1277. The migration of black holes in clusters may be a common occurrence.« less

Characteristics of CMEs observed in the heliosphere using Helios photometer data. [coronal mass ejection

NASA Technical Reports Server (NTRS)

Webb, D. F.; Jackson, B. V.

1992-01-01

The zodiacal light photometers on the two Helios spacecraft have been used to detect and study mass ejections and other phenomena emanating from the sun and traversing the heliosphere within 1 AU. We have recently compiled a complete list of all of the significant white light transient events detected from the 90-deg photometers on both Helios spacecraft. This is a preliminary report on the long-term frequency of occurrence of these events; it emphasizes newly processed data from Helios-l from 1975 through 1982 and viewed south of the ecliptic. With the large Helios photometer data base, we will be able to identify the fraction of the 90 deg events which are heliospheric CMEs and determine their characteristics.

Evolution of the Uranus-neptune Planetesimal Swarm: Consequences for the Earth

NASA Technical Reports Server (NTRS)

Shoemaker, E. M.; Wolfe, R. F.

1984-01-01

The evolution of planetesimals in the outer Solar System were evaluated, both stellar and planetary encounters. About 20% of the Uranus-Neptune planetesimals (UNP's) enter the comet cloud and are stored primarily in the region inside the observational limits of the Oort cloud. Half of the comets have suruived to the present time; the cloud now has a mass of the order of Jupiter's mass. Most UNP's are ejected from the Solar system, and about half of the planetesimal swarm is passed to the control of Jupiter prior to ejection. Jupiter's perturbations drive a large flux of these planetesimals into Earth-crossing orbits, and it now appears highly probable that UNP's account for most of the heavy bombardment of the Moon and Earth.

Sodium-bicarbonate cotransport in retinal Müller (glial) cells of the salamander.

PubMed

Newman, E A

1991-12-01

An electrogenic Na+/HCO3- cotransport system was studied in freshly dissociated Müller cells of the salamander retina. Cotransporter currents were recorded from isolated cells using the whole-cell, voltage-clamp technique following the block of K+ conductance with external Ba2+ and internal Cs+. At constant pHo, an outward current was evoked when extracellular HCO3- concentration was raised by pressure ejecting a HCO3(-)-buffered solution onto the surface of cells bathed in nominally HCO3(-)-free solution. The HCO3(-)-evoked outward current was reduced to 4.4% of control by 0.5 mM DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonate), to 28.8% of control by 2 mM DNDS (4,4'-dinitrostilbene-2,2'-disulfonate), and to 28.4% of control by 2 mM harmaline. Substitution of choline for Na+ in bath and ejection solutions reduced the response to 1.3% of control. Bicarbonate-evoked currents of normal magnitude were recorded when methane sulfonate was substituted for Cl- in bath, ejection, and intracellular solutions. Similarly, an outward current was evoked when extracellular Na+ concentration was raised in the presence of HCO3-. The Na(+)-evoked response was reduced to 16.2% of control by 2 mM DNDS and was abolished by removal of HCO3- from bath and ejection solutions. Taken together, these results (block by stilbenes and harmaline, HCO3- and Na+ dependence, Cl- independence) indicate that salamander Müller cells possess an electrogenic Na+/HCO3- cotransport system. Na+/HCO3- cotransporter sites were localized primarily at the endfoot region of Müller cells. Ejection of HCO3- onto the endfoot evoked outward currents 10 times larger than currents evoked by ejections onto the opposite (distal) end of the cell. The reversal potential of the cotransporter was determined by DNDS block of cotransport current. In the absence of a transmembrane HCO3- gradient, the reversal potential varied systematically as a function of the transmembrane Na+ gradient. The reversal potential was -0.1 mV for a [Na+]o:[Na+]i ratio of 1:1 and -25.2 mV for a Na+ gradient ratio of 7.4:1. Based on these values, the estimated stoichiometry of the cotransporter was 2.80 +/- 0.13:1 (HCO3-:Na+). Possible functions of the glial cell Na+/HCO3- cotransporter, including the regulation of CO2 in the retina and the regulation of cerebral blood flow, are discussed.

Experimental Study of Thermal Runaway Process of 18650 Lithium-Ion Battery

PubMed Central

Liu, Jingjing; Wang, Zhirong; Gong, Junhui; Liu, Kai; Wang, Hao; Guo, Linsheng

2017-01-01

This study addresses the effects of the SOC (State of Charge) and the charging–discharging process on the thermal runaway of 18650 lithium-ion batteries. A series of experiments were conducted on an electric heating and testing apparatus. The experimental results indicate that 6 W is the critical heating power for 40% SOC. With a 20 W constant heating rate, the thermal runaway initial temperature of the lithium-ion battery decreases with the increasing SOC. The final thermal runaway temperature increases with the SOC when the SOC is lower than 80%. However, a contrary conclusion was obtained when the SOC was higher than 80%. Significant mass loss, accompanied by an intense exothermic reaction, took place under a higher SOC. The critical charging current, beyond which the thermal runaway occurs, was found to be 2.6 A. The thermal runaway initial temperature decreases with the increasing charging current, while the intensity of the exothermic reaction varies inversely. Mass ejection of gas and electrolytes exists during thermal runaway when the charging current is higher than 10.4 A, below which only a large amount of gas is released. The thermal runaway initial temperature of discharging is higher than that of non-discharging. PMID:28772588

Experimental Study of Thermal Runaway Process of 18650 Lithium-Ion Battery.

PubMed

Liu, Jingjing; Wang, Zhirong; Gong, Junhui; Liu, Kai; Wang, Hao; Guo, Linsheng

2017-02-25

This study addresses the effects of the SOC (State of Charge) and the charging-discharging process on the thermal runaway of 18650 lithium-ion batteries. A series of experiments were conducted on an electric heating and testing apparatus. The experimental results indicate that 6 W is the critical heating power for 40% SOC. With a 20 W constant heating rate, the thermal runaway initial temperature of the lithium-ion battery decreases with the increasing SOC. The final thermal runaway temperature increases with the SOC when the SOC is lower than 80%. However, a contrary conclusion was obtained when the SOC was higher than 80%. Significant mass loss, accompanied by an intense exothermic reaction, took place under a higher SOC. The critical charging current, beyond which the thermal runaway occurs, was found to be 2.6 A. The thermal runaway initial temperature decreases with the increasing charging current, while the intensity of the exothermic reaction varies inversely. Mass ejection of gas and electrolytes exists during thermal runaway when the charging current is higher than 10.4 A, below which only a large amount of gas is released. The thermal runaway initial temperature of discharging is higher than that of non-discharging.

Double core evolution. 7: The infall of a neutron star through the envelope of its massive star companion

NASA Technical Reports Server (NTRS)

Terman, James L.; Taam, Ronald E.; Hernquist, Lars

1995-01-01

Binary systems with properties similar to those of high-mass X-ray binaries are evolved through the common envelope phase. Three-dimensional simulations show that the timescale of the infall phase of the neutron star depends upon the evolutionary state of its massive companion. We find that tidal torques more effectively accelerate common envelope evolution for companions in their late core helium-burning stage and that the infall phase is rapid (approximately several initial orbital periods). For less evolved companions the decay of the orbit is longer; however, once the neutron star is deeply embedded within the companion's envelope the timescale for orbital decay decreases rapidly. As the neutron star encounters the high-density region surrounding the helium core of its massive companion, the rate of energy loss from the orbit increases dramatically leading to either partial or nearly total envelope ejection. The outcome of the common envelope phase depends upon the structure of the evolved companion. In particular, it is found that the entire common envelope can be ejected by the interaction of the neutron star with a red supergiant companion in binaries with orbital periods similar to those of long-period Be X-ray binaries. For orbital periods greater than or approximately equal to 0.8-2 yr (for companions of mass 12-24 solar mass) it is likely that a binary will survive the common envelope phase. For these systems, the structure of the progenitor star is characterized by a steep density gradient above the helium core, and the common envelope phase ends with a spin up of the envelope to within 50%-60% of corotation and with a slow mass outflow. The efficiency of mass ejection is found to be approximately 30%-40%. For less evolved companions, there is insufficient energy in the orbit to unbind the common envelope and only a fraction of it is ejected. Since the timescale for orbital decay is always shorter than the mass-loss timescale from the common envelope, the two cores will likely merge to form a Thorne-Zytkow object. Implications for the origin of Cyg X-3, an X-ray source consisting of a Wolf-Rayet star and a compact companion, and for the fate of the remnant binary consisting of a helium star and a neutron star are briefly discussed.

Energy ejection in the collapse of a cold spherical self-gravitating cloud

NASA Astrophysics Data System (ADS)

Joyce, M.; Marcos, B.; Sylos Labini, F.

2009-08-01

When an open system of classical point particles interacting by Newtonian gravity collapses and relaxes violently, an arbitrary amount of energy may, in principle, be carried away by particles which escape to infinity. We investigate here, using numerical simulations, how this released energy and other related quantities (notably the binding energy and size of the virialized structure) depend on the initial conditions, for the one-parameter family of starting configurations given by randomly distributing N cold particles in a spherical volume. Previous studies have established that the minimal size reached by the system scales approximately as N1/3, a behaviour which follows trivially when the growth of perturbations (which regularize the singularity of the cold collapse in the N -> ∞ limit) is assumed to be unaffected by the boundaries. Our study shows that the energy ejected grows approximately in proportion to N1/3, while the fraction of the initial mass ejected grows only very slowly with N, approximately logarithmically, in the range of N simulated. We examine in detail the mechanism of this mass and energy ejection, showing explicitly that it arises from the interplay of the growth of perturbations with the finite size of the system. A net lag of particles compared to their uniform spherical collapse trajectories develops first at the boundaries and then propagates into the volume during the collapse. Particles in the outer shells are then ejected as they scatter through the time-dependent potential of an already re-expanding central core. Using modified initial configurations, we explore the importance of fluctuations at different scales and discreteness (i.e. non-Vlasov) effects in the dynamics.

High-Speed Bullet Ejections during the AGB to Planetary Nebula Transition: A Study of the Carbon Star V Hydrae

NASA Astrophysics Data System (ADS)

Sahai, Raghvendra

2017-08-01

The carbon star V Hya is experiencing heavy mass loss as it undergoes the transition from an AGB star to a planetary nebula (PN). This is possibly the earliest object known in this brief phase, which is so short that few nearby stars are likely to be caught in the act. Molecular observations reveal that a bipolar nebula has been established even at this early stage. Using STIS, we obtained high spatial-resolution long-slit optical spectra of V Hya spanning 3 epochs spaced apart by a year during each of two periods (2002-2004, 2011-2013). These data reveal high-velocity emission in [SII] lines from compact blobs located both on- and off-source, with the ejection axis executing a flip-flop, both in, and perpendicular to, the sky-plane. We have proposed a detailed model in which V Hya ejects high-speed (200-250 km/s) bullets once every 8.5 yr associated with periastron passage of a binary companion in an eccentric orbit with an 8.5 yr period. We suggest that the jet driver is an accretion disk (produced by gravitational capture of material from the primary) that is warped and precessing. Our model predicts the locations of previously ejected bullets in V Hya and future epochs at which new bullets will emerge. We now propose new STIS observations of these remarkable bullet ejections over two new epochs well separated from previous ones, to robustly test our model. The proposed observations will provide us with an unprecedented opportunity to look on as V Hya's circumstellar envelope is sculpted by these bullets. Our study will help solve the long-standing puzzle of how the spherical mass-loss envelopes of AGB stars evolve into bipolar and multipolar PNe.

Operational Parameters, Considerations, and Design Decisions for Resource-Constrained Ion Trap Mass Spectrometers

NASA Technical Reports Server (NTRS)

Danell, Ryan M.; VanAmerom, Friso H. W.; Pinnick, Veronica; Cotter, Robert J.; Brickerhoff, William; Mahaffy, Paul

2011-01-01

Mass spectrometers are increasingly finding applications in new and unique areas, often in situations where key operational resources (i.e. power, weight and size) are limited. One such example is the Mars Organic Molecule Analyzer (MOMA). This instrument is a joint venture between NASA and the European Space Agency (ESA) to develop an ion trap mass spectrometer for chemical analysis on Mars. The constraints on such an instrument are significant as are the performance requirements. While the ideal operating parameters for an ion trap are generally well characterized, methods to maintain analytical performance with limited power and system weight need to be investigated and tested. Methods Experiments have been performed on two custom ion trap mass spectrometers developed as prototypes for the MOMA instrument. This hardware consists of quadrupole ion trap electrodes that are 70% the size of common commercial instrumentation. The trapping RF voltage is created with a custom tank circuit that can be tuned over a range of RF frequencies and is driven using laboratory supplies and amplifiers. The entire instrument is controlled with custom Lab VIEW software that allows a high degree of flexibility in the definition of the scan function defining the ion trap experiment. Ions are typically generated via an internal electron ionization source, however, a laser desorption source is also in development for analysis of larger intact molecules. Preliminary Data The main goals in this work have been to reduce the power required to generate the radio frequency trapping field used in an ion trap mass spectrometer. Generally minimizing the power will also reduce the volume and mass of the electronics to support the instrument. In order to achieve optimum performance, commercial instruments typically utilize RF frequencies in the 1 MHz range. Without much concern for power usage, they simply generate the voltage required to access the mass range of interest. In order to reduce the required RF voltage (and power), operation of the ion trap at lower RF frequencies has been investigated. Surprisingly, the performance of the instrument has only been slightly degraded at RF frequencies all the way down to 500 kHz. Mass resolution is relatively stable to this point and depending on the resonant ejection point used, the peak intensity is also quite stable. To date only masses up to m/z 200 have been fully investigated, however, additional studies are planned to verify the performance with higher mass ions. The lower frequency and voltage should reduce the pseudo potential well depth, eventually affecting the trapping efficiency of the instrument -- effect that could manifest itself in significantly limiting the mass range of trapped ions. Other methods to reduce the RF power while maintaining analytical performance are also under investigation. This includes ion ejection at lower q(sub z) values to access a given mass with a lower RF voltage. The loss of mass resolution at lower q(sub eject) points has been measured and current work is underway to leverage scan speed and the use of non-linear resonances in order to counter this trend. The overall trap performance under this range of operating conditions will be presented with a goal of identifying what trade-offs are acceptable.

Powerful non-geoeffective interplanetary disturbance of July 2012 observed by muon hodoscope URAGAN

NASA Astrophysics Data System (ADS)

Astapov, I. I.; Barbashina, N. S.; Petrukhin, A. A.; Shutenko, V. V.; Veselovsky, I. S.

2015-12-01

The most powerful coronal mass ejection of the 24th solar cycle took place on the opposite side of the Sun on July 23, 2012 and had no geomagnetic consequences. Nevertheless, as a result of passing of the ejection through the heliosphere, variations of galactic cosmic rays flux were observed on the Earth. These variations were registered by the muon hodoscope URAGAN (MEPhI, Moscow). Muon flux angular distributions on the Earth's surface are reported and analyzed.

Linear theory on temporal instability of megahertz faraday waves for monodisperse microdroplet ejection.

PubMed

Tsai, Shirley C; Tsai, Chen S

2013-08-01

A linear theory on temporal instability of megahertz Faraday waves for monodisperse microdroplet ejection based on mass conservation and linearized Navier-Stokes equations is presented using the most recently observed micrometer- sized droplet ejection from a millimeter-sized spherical water ball as a specific example. The theory is verified in the experiments utilizing silicon-based multiple-Fourier horn ultrasonic nozzles at megahertz frequency to facilitate temporal instability of the Faraday waves. Specifically, the linear theory not only correctly predicted the Faraday wave frequency and onset threshold of Faraday instability, the effect of viscosity, the dynamics of droplet ejection, but also established the first theoretical formula for the size of the ejected droplets, namely, the droplet diameter equals four-tenths of the Faraday wavelength involved. The high rate of increase in Faraday wave amplitude at megahertz drive frequency subsequent to onset threshold, together with enhanced excitation displacement on the nozzle end face, facilitated by the megahertz multiple Fourier horns in resonance, led to high-rate ejection of micrometer- sized monodisperse droplets (>10(7) droplets/s) at low electrical drive power (<;1 W) with short initiation time (<;0.05 s). This is in stark contrast to the Rayleigh-Plateau instability of a liquid jet, which ejects one droplet at a time. The measured diameters of the droplets ranging from 2.2 to 4.6 μm at 2 to 1 MHz drive frequency fall within the optimum particle size range for pulmonary drug delivery.

Centrifugally driven winds from protostellar accretion discs - I. Formulation and initial results

NASA Astrophysics Data System (ADS)

Nolan, C. A.; Salmeron, R.; Federrath, C.; Bicknell, G. V.; Sutherland, R. S.

2017-10-01

Protostellar discs play an important role in star formation, acting as the primary mass reservoir for accretion on to young stars and regulating the extent to which angular momentum and gas is released back into stellar nurseries through the launching of powerful disc winds. In this study, we explore how disc structure relates to the properties of the wind-launching region, mapping out the regions of protostellar discs where wind launching could be viable. We combine a series of 1.5D semi-analytic, steady-state, vertical disc-wind solutions into a radially extended 1+1.5D model, incorporating all three diffusion mechanisms (Ohm, Hall and ambipolar). We observe that the majority of mass outflow via disc winds occurs over a radial width of a fraction of an astronomical unit, with outflow rates attenuating rapidly on either side. We also find that the mass accretion rate, magnetic field strength and surface density profile each have significant effects on both the location of the wind-launching region and the ejection/accretion ratio \\dot{M}_out/\\dot{M}_in. Increasing either the accretion rate or the magnetic field strength corresponds to a shift of the wind-launching region to smaller radii and a decrease in \\dot{M}_out/\\dot{M}_in, while increasing the surface density corresponds to launching regions at larger radii with increased \\dot{M}_out/\\dot{M}_in. Finally, we discover a class of disc winds containing an ineffective launching configuration at intermediate radii, leading to two radially separated regions of wind launching and diminished \\dot{M}_out/\\dot{M}_in. We find that the wind locations and ejection/accretion ratio are consistent with current observational and theoretical estimates.

Echocardiographic Manifestations of Glycogen Storage Disease III: Increase in Wall Thickness and Left Ventricular Mass over Time

PubMed Central

Vertilus, Shawyntee M.; Austin, Stephanie L.; Foster, Kimberly S.; Boyette, Keri E.; Bali, Deeksha; Li, Jennifer S.; Kishnani, Priya S.; Wechsler, Stephanie Burns

2013-01-01

Purpose Glycogen Storage Disease (GSD) type III, glycogen debranching enzyme deficiency, causes accumulation of glycogen in liver, skeletal, and cardiac muscle. Some patients develop increased left ventricular (LV) thickness by echocardiography, but the rate of increase and its significance remain unclear. Methods We evaluated 33 patients with GSD type III, 23 with IIIa and 10 with IIIb, ages 1 month – 55.5 yrs, by echocardiography for wall thickness, LV mass, shortening and ejection fractions, at 1 time point (n = 33) and at 2 time points in patients with more than 1 echocardiogram (13 of the 33). Results Of 23 cross-sectional patients with type IIIa, 12 had elevated LV mass, 11 had elevated wall thickness. One type IIIb patient had elevated LV mass but 4 had elevated wall thickness. For those with multiple observations, 9 of 10 with type IIIa developed increased LV mass over time, with 3 already increased at first measurement. Shortening and ejection fractions were generally normal. Conclusion Elevated LV mass and wall thickness is more common in patients with type IIIa but develops rarely in type IIIb, though ventricular systolic function is preserved. This suggests serial echocardiograms with attention to LV thickness and mass are important for care of these patients. PMID:20526204

Probing SEP Acceleration Processes With Near-relativistic Electrons

NASA Astrophysics Data System (ADS)

Haggerty, Dennis K.; Roelof, Edmond C.

2009-11-01

Processes in the solar corona are prodigious accelerators of near-relativistic electrons. Only a small fraction of these electrons escape the low corona, yet they are by far the most abundant species observed in Solar Energetic Particle events. These beam-like energetic electron events are sometimes time-associated with coronal mass ejections from the western solar hemisphere. However, a significant number of events are observed without any apparent association with a transient event. The relationship between solar energetic particle events, coronal mass ejections, and near-relativistic electron events are better ordered when we classify the intensity time profiles during the duration of the beam-like anisotropies into three broad categories: 1) Spikes (rapid and equal rise and decay) 2) Pulses (rapid rise, slower decay) and 3) Ramps (rapid rise followed by a plateau). We report on the results of a study that is based on our catalog (covering nearly the complete Solar Cycle 23) of 216 near-relativistic electron events and their association with: solar electromagnetic emissions, shocks driven by coronal mass ejections, models of the coronal magnetic fields and energetic protons. We conclude that electron events with time-intensity profiles of Spikes and Pulses are associated with explosive events in the low corona while events with time-intensity profiles of Ramps are associated with the injection/acceleration process of the CME driven shock.

Black hole binaries dynamically formed in globular clusters

NASA Astrophysics Data System (ADS)

Park, Dawoo; Kim, Chunglee; Lee, Hyung Mok; Bae, Yeong-Bok; Belczynski, Krzysztof

2017-08-01

We investigate properties of black hole (BH) binaries formed in globular clusters via dynamical processes, using directN-body simulations. We pay attention to effects of BH mass function on the total mass and mass ratio distributions of BH binaries ejected from clusters. First, we consider BH populations with two different masses in order to learn basic differences from models with single-mass BHs only. Secondly, we consider continuous BH mass functions adapted from recent studies on massive star evolution in a low metallicity environment, where globular clusters are formed. In this work, we consider only binaries that are formed by three-body processes and ignore stellar evolution and primordial binaries for simplicity. Our results imply that most BH binary mergers take place after they get ejected from the cluster. Also, mass ratios of dynamically formed binaries should be close to 1 or likely to be less than 2:1. Since the binary formation efficiency is larger for higher-mass BHs, it is likely that a BH mass function sampled by gravitational-wave observations would be weighed towards higher masses than the mass function of single BHs for a dynamically formed population. Applying conservative assumptions regarding globular cluster populations such as small BH mass fraction and no primordial binaries, the merger rate of BH binaries originated from globular clusters is estimated to be at least 6.5 yr-1 Gpc-3. Actual rate can be up to more than several times of our conservative estimate.

A dynamic magnetic tension force as the cause of failed solar eruptions

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

Myers, Clayton E.; Yamada, Masaaki; Ji, Hantao

Coronal mass ejections are solar eruptions driven by a sudden release of magnetic energy stored in the Sun's corona. In many cases, this magnetic energy is stored in long-lived, arched structures called magnetic flux ropes. When a flux rope destabilizes, it can either erupt and produce a coronal mass ejection or fail and collapse back towards the Sun. The prevailing belief is that the outcome of a given event is determined by a magnetohydrodynamic force imbalance called the torus instability. This belief is challenged, however, by observations indicating that torus-unstable flux ropes sometimes fail to erupt. This contradiction has notmore » yet been resolved because of a lack of coronal magnetic field measurements and the limitations of idealized numerical modelling. In this paper, we report the results of a laboratory experiment that reveal a previously unknown eruption criterion below which torus-unstable flux ropes fail to erupt. We find that such 'failed torus' events occur when the guide magnetic field (that is, the ambient field that runs toroidally along the flux rope) is strong enough to prevent the flux rope from kinking. Under these conditions, the guide field interacts with electric currents in the flux rope to produce a dynamic toroidal field tension force that halts the eruption. Lastly, this magnetic tension force is missing from existing eruption models, which is why such models cannot explain or predict failed torus events.« less

A dynamic magnetic tension force as the cause of failed solar eruptions

DOE PAGES

Myers, Clayton E.; Yamada, Masaaki; Ji, Hantao; ...

2015-12-23

Coronal mass ejections are solar eruptions driven by a sudden release of magnetic energy stored in the Sun's corona. In many cases, this magnetic energy is stored in long-lived, arched structures called magnetic flux ropes. When a flux rope destabilizes, it can either erupt and produce a coronal mass ejection or fail and collapse back towards the Sun. The prevailing belief is that the outcome of a given event is determined by a magnetohydrodynamic force imbalance called the torus instability. This belief is challenged, however, by observations indicating that torus-unstable flux ropes sometimes fail to erupt. This contradiction has notmore » yet been resolved because of a lack of coronal magnetic field measurements and the limitations of idealized numerical modelling. In this paper, we report the results of a laboratory experiment that reveal a previously unknown eruption criterion below which torus-unstable flux ropes fail to erupt. We find that such 'failed torus' events occur when the guide magnetic field (that is, the ambient field that runs toroidally along the flux rope) is strong enough to prevent the flux rope from kinking. Under these conditions, the guide field interacts with electric currents in the flux rope to produce a dynamic toroidal field tension force that halts the eruption. Lastly, this magnetic tension force is missing from existing eruption models, which is why such models cannot explain or predict failed torus events.« less

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.

Multi-viewpoint Coronal Mass Ejection Catalog Based on STEREO COR2 Observations

NASA Astrophysics Data System (ADS)

Vourlidas, Angelos; Balmaceda, Laura A.; Stenborg, Guillermo; Dal Lago, Alisson

2017-04-01

We present the first multi-viewpoint coronal mass ejection (CME) catalog. The events are identified visually in simultaneous total brightness observations from the twin SECCHI/COR2 coronagraphs on board the Solar Terrestrial Relations Observatory mission. The Multi-View CME Catalog differs from past catalogs in three key aspects: (1) all events between the two viewpoints are cross-linked, (2) each event is assigned a physics-motivated morphological classification (e.g., jet, wave, and flux rope), and (3) kinematic and geometric information is extracted semi-automatically via a supervised image segmentation algorithm. The database extends from the beginning of the COR2 synoptic program (2007 March) to the end of dual-viewpoint observations (2014 September). It contains 4473 unique events with 3358 events identified in both COR2s. Kinematic properties exist currently for 1747 events (26% of COR2-A events and 17% of COR2-B events). We examine several issues, made possible by this cross-linked CME database, including the role of projection on the perceived morphology of events, the missing CME rate, the existence of cool material in CMEs, the solar cycle dependence on CME rate, speeds and width, and the existence of flux rope within CMEs. We discuss the implications for past single-viewpoint studies and for Space Weather research. The database is publicly available on the web including all available measurements. We hope that it will become a useful resource for the community.

Direct Evidence of an Eruptive, Filament-hosting Magnetic Flux Rope Leading to a Fast Solar Coronal Mass Ejection

NASA Astrophysics Data System (ADS)

Chen, Bin; Bastian, T. S.; Gary, D. E.

2014-10-01

Magnetic flux ropes (MFRs) are believed to be at the heart of solar coronal mass ejections (CMEs). A well-known example is the prominence cavity in the low corona that sometimes makes up a three-part white-light (WL) CME upon its eruption. Such a system, which is usually observed in quiet-Sun regions, has long been suggested to be the manifestation of an MFR with relatively cool filament material collecting near its bottom. However, observational evidence of eruptive, filament-hosting MFR systems has been elusive for those originating in active regions. By utilizing multi-passband extreme-ultraviolet (EUV) observations from Solar Dynamics Observatory/Atmospheric Imaging Assembly, we present direct evidence of an eruptive MFR in the low corona that exhibits a hot envelope and a cooler core; the latter is likely the upper part of a filament that undergoes a partial eruption, which is later observed in the upper corona as the coiled kernel of a fast, WL CME. This MFR-like structure exists more than 1 hr prior to its eruption, and displays successive stages of dynamical evolution, in which both ideal and non-ideal physical processes may be involved. The timing of the MFR kinematics is found to be well correlated with the energy release of the associated long-duration C1.9 flare. We suggest that the long-duration flare is the result of prolonged energy release associated with the vertical current sheet induced by the erupting MFR.

Biomechanical investigation of thoracolumbar spine in different postures during ejection using a combined finite element and multi-body approach.

PubMed

Du, Chengfei; Mo, Zhongjun; Tian, Shan; Wang, Lizhen; Fan, Jie; Liu, Songyang; Fan, Yubo

2014-11-01

The aim of this study is to investigate the dynamic response of a multi-segment model of the thoracolumbar spine and determine how the sitting posture affects the response under the impact of ejection. A nonlinear finite element model of the thoracolumbar-pelvis complex (T9-S1) was developed and validated. A multi-body dynamic model of a pilot was also constructed so an ejection seat restraint system could be incorporated into the finite element model. The distribution of trunk mass on each vertebra was also considered in the model. Dynamics analysis showed that ejection impact induced obvious axial compression and anterior flexion of the spine, which may contribute to spinal injuries. Compared with a normal posture, the relaxed posture led to an increase in stress on the cortical wall, endplate, and intradiscal pressure of 43%, 10%, 13%, respectively, and accordingly increased the risk of inducing spinal injuries. Copyright © 2014 John Wiley & Sons, Ltd.

Ejection of rocky and icy material from binary star systems: implications for the origin and composition of 1I/`Oumuamua

NASA Astrophysics Data System (ADS)

Jackson, Alan P.; Tamayo, Daniel; Hammond, Noah; Ali-Dib, Mohamad; Rein, Hanno

2018-06-01

In single-star systems like our own Solar system, comets dominate the mass budget of bodies ejected into interstellar space, since they form further away and are less tightly bound. However, 1I/`Oumuamua, the first interstellar object detected, appears asteroidal in its spectra and lack of detectable activity. We argue that the galactic budget of interstellar objects like 1I/`Oumuamua should be dominated by planetesimal material ejected during planet formation in circumbinary systems, rather than in single-star systems or widely separated binaries. We further show that in circumbinary systems, rocky bodies should be ejected in comparable numbers to icy ones. This suggests that a substantial fraction of interstellar objects discovered in future should display an active coma. We find that the rocky population, of which 1I/`Oumuamua seems to be a member, should be predominantly sourced from A-type and late B-star binaries.

Solar Coronal Jets: Observations, Theory, and Modeling

NASA Technical Reports Server (NTRS)

Raouafi, N. E.; Patsourakos, S.; Pariat, E.; Young, P. R.; Sterling, A. C.; Savcheva, A.; Shimojo, M.; Moreno-Insertis, F.; DeVore, C. R.; Archontis, V.;

Solar Coronal Jets: Observations, Theory, and Modeling

NASA Technical Reports Server (NTRS)

Raouafi, N. E.; Patsourakos, S.; Pariat, E.; Young, P. R.; Sterling, A.; Savcheva, A.; Shimojo, M.; Moreno-Insertis, F.; Devore, C. R.; Archontis, V.;

Semi-inclusive charged-current neutrino-nucleus reactions

DOE PAGES

Moreno, O.; Donnelly, T. W.; Van Orden, J. W.; ...

2014-07-17

The general, universal formalism for semi-inclusive charged-current (anti)neutrino-nucleus reactions is given for studies of any hadronic system, namely, either nuclei or the nucleon itself. The detailed developments are presented with the former in mind and are further specialized to cases where the final-state charged lepton and an ejected nucleon are presumed to be detected. General kinematics for such processes are summarized and then explicit expressions are developed for the leptonic and hadronic tensors involved and for the corresponding responses according to the usual charge, longitudinal and transverse projections, keeping finite the masses of all particles involved. In the case ofmore » the hadronic responses, general symmetry principles are invoked to determine which contributions can occur. As a result, the general leptonic-hadronic tensor contraction is given as well as the cross section for the process.« less

Physics of magnetic flux ropes

NASA Astrophysics Data System (ADS)

Russell, C. T.; Priest, E. R.; Lee, L. C.

The present work encompasses papers on the structure, waves, and instabilities of magnetic flux ropes (MFRs), photospheric flux tubes (PFTs), the structure and heating of coronal loops, solar prominences, coronal mass ejections and magnetic clouds, flux ropes in planetary ionospheres, the magnetopause, magnetospheric field-aligned currents and flux tubes, and the magnetotail. Attention is given to the equilibrium of MFRs, resistive instability, magnetic reconnection and turbulence in current sheets, dynamical effects and energy transport in intense flux tubes, waves in solar PFTs, twisted flux ropes in the solar corona, an electrodynamical model of solar flares, filament cooling and condensation in a sheared magnetic field, the magnetopause, the generation of twisted MFRs during magnetic reconnection, ionospheric flux ropes above the South Pole, substorms and MFR structures, evidence for flux ropes in the earth magnetotail, and MFRs in 3D MHD simulations.

Evaluation of Pulse Counting for the Mars Organic Mass Analyzer (MOMA) Ion Trap Detection Scheme

NASA Technical Reports Server (NTRS)

Van Amerom, Friso H.; Short, Tim; Brinckerhoff, William; Mahaffy, Paul; Kleyner, Igor; Cotter, Robert J.; Pinnick, Veronica; Hoffman, Lars; Danell, Ryan M.; Lyness, Eric I.

2011-01-01

The Mars Organic Mass Analyzer is being developed at Goddard Space Flight Center to identify organics and possible biological compounds on Mars. In the process of characterizing mass spectrometer size, weight, and power consumption, the use of pulse counting was considered for ion detection. Pulse counting has advantages over analog-mode amplification of the electron multiplier signal. Some advantages are reduced size of electronic components, low power consumption, ability to remotely characterize detector performance, and avoidance of analog circuit noise. The use of pulse counting as a detection method with ion trap instruments is relatively rare. However, with the recent development of high performance electrical components, this detection method is quite suitable and can demonstrate significant advantages over analog methods. Methods A prototype quadrupole ion trap mass spectrometer with an internal electron ionization source was used as a test setup to develop and evaluate the pulse-counting method. The anode signal from the electron multiplier was preamplified. The an1plified signal was fed into a fast comparator for pulse-level discrimination. The output of the comparator was fed directly into a Xilinx FPGA development board. Verilog HDL software was written to bin the counts at user-selectable intervals. This system was able to count pulses at rates in the GHz range. The stored ion count nun1ber per bin was transferred to custom ion trap control software. Pulse-counting mass spectra were compared with mass spectra obtained using the standard analog-mode ion detection. Prelin1inary Data Preliminary mass spectra have been obtained for both analog mode and pulse-counting mode under several sets of instrument operating conditions. Comparison of the spectra revealed better peak shapes for pulse-counting mode. Noise levels are as good as, or better than, analog-mode detection noise levels. To artificially force ion pile-up conditions, the ion trap was overfilled and ions were ejected at very high scan rates. Pile-up of ions was not significant for the ion trap under investigation even though the ions are ejected in so-called 'ion-micro packets'. It was found that pulse counting mode had higher dynamic range than analog mode, and that the first amplification stage in analog mode can distort mass peaks. The inherent speed of the pulse counting method also proved to be beneficial to ion trap operation and ion ejection characterization. Very high scan rates were possible with pulse counting since the digital circuitry response time is so much smaller than with the analog method. Careful investigation of the pulse-counting data also allowed observation of the applied resonant ejection frequency during mass analysis. Ejection of ion micro packets could be clearly observed in the binned data. A second oscillation frequency, much lower than the secular frequency, was also observed. Such an effect was earlier attributed to the oscillation of the total plasma cloud in the ion trap. While the components used to implement pulse counting are quite advanced, due to their prevalence in consumer electronics, the cost of this detection system is no more than that of an analog mode system. Total pulse-counting detection system electronics cost is under $250

Coronal Mass Ejections and their Implications for the Corona and Heliosphere

NASA Technical Reports Server (NTRS)

Antiochos, Spiro K.

2008-01-01

Coronal mass ejections (CMEs) are the largest and most energetic form of transients that connect the Sun to the heliosphere. They are critically important both for understanding the physical mechanisms of explosive solar activity and for predicting space weather. Furthermore they are an extreme example of how cross-scale coupling can play a critical role in determining the properties of a large-scale dynamical system. In this presentation CME theories are reviewed and the latest results from 3D numerical modeling of CME initiation propagation to the heliosphere are presented. In particular the focus is on the breakout model, but many of the results hold for the flux rope models as well. The implications of these results for understanding heliospheric structure and dynamics and for upcoming space missions will be discussed.

Radiation Belt response to the July 2017 Coronal Mass Ejection and the Interplanetary Shock

NASA Astrophysics Data System (ADS)

Kanekal, S. G.; Baker, D. N.; Jones, A. D.; Schiller, Q. A.; Sibeck, D. G.; Elkington, S. R.; Hoxie, V. C.; Jaynes, A. N.; Li, X.; Zhao, H.; Blake, J. B.; Claudepierre, S. G.; Fennell, J. F.; Turner, D. L.

2017-12-01

A coronal mass ejection that erupted on July 14, 2017 impacted the radiation belts on July 16, 2017 and resulted in a moderate geomagnetic storm. The immediate response of the energetic electrons to the interplanetary shock ahead of the CME, showed hock-induced energization as well as drift echoes in the L range of 4 to 5 . Increased electron fluxes were seen to energies up to 5 MeV as observed by the Relativistic Electron and Proton Telescope and the Magnetic Electron and Ion Sensors on board NASA's Van Allen Probes. We report on these observations, both immediately after the IP shock passage and the more gradual response to the CME. we discuss the observation in the context of electron dynamics in the terrestrial radiation belts.

The symmetry and mass of halo Coronal Mass Ejections (CMEs) as quantitative predictors for severe space weather at Earth.

NASA Astrophysics Data System (ADS)

Fuselier, S.; Allegrini, F.; Bzowski, M.; Dayeh, M. A.; Desai, M. I.; Funsten, H. O.; Galli, A.; Heirtzler, D.; Janzen, P. H.; Kubiak, M. A.; Kucharek, H.; Lewis, W. S.; Livadiotis, G.; McComas, D. J.; Moebius, E.; Petrinec, S. M.; Quinn, M. S.; Schwadron, N.; Sokol, J. M.; Trattner, K. J.

2014-12-01

The Bureau of Meteorology's Space Weather Service operates an alert service for severe space weather events. The service relies on a statistical model which ingests observations of M and X class solar flares at or shortly after the time of the flare to predict the occurrence and severity of terrestrial impacts with a lead time of 1 to 4 days. This model has been operational since 2012 and caters to the needs of critical infrastructure groups in the Australian region. This paper reports on improvements to the forecast model by including SOHO LASCO coronagraph observations of Coronal Mass Ejections (CMEs). The coronagraphs are analysed to determine the Earthward direction parameter and the integrated intensity as a measure of the CME mass. Both of these parameters can help to predict whether a CME will be geo-effective. This work aims to increase the accuracy of the model predictions and lower the rate of false positives, as well as providing an estimate of the expected level of geomagnetic storm intensity.

The symmetry and mass of halo Coronal Mass Ejections (CMEs) as quantitative predictors for severe space weather at Earth.

NASA Astrophysics Data System (ADS)

Freeland, L. E.; Terkildsen, M. B.

2015-12-01

The Bureau of Meteorology's Space Weather Service operates an alert service for severe space weather events. The service relies on a statistical model which ingests observations of M and X class solar flares at or shortly after the time of the flare to predict the occurrence and severity of terrestrial impacts with a lead time of 1 to 4 days. This model has been operational since 2012 and caters to the needs of critical infrastructure groups in the Australian region. This paper reports on improvements to the forecast model by including SOHO LASCO coronagraph observations of Coronal Mass Ejections (CMEs). The coronagraphs are analysed to determine the Earthward direction parameter and the integrated intensity as a measure of the CME mass. Both of these parameters can help to predict whether a CME will be geo-effective. This work aims to increase the accuracy of the model predictions and lower the rate of false positives, as well as providing an estimate of the expected level of geomagnetic storm intensity.

Theoretical model of gravitational perturbation of current collector axisymmetric flow field

NASA Astrophysics Data System (ADS)

Walker, John S.; Brown, Samuel H.; Sondergaard, Neal A.

1989-03-01

Some designs of liquid metal collectors in homopolar motors and generators are essentially rotating liquid metal fluids in cylindrical channels with free surfaces and will, at critical rotational speeds, become unstable. The role of gravity in modifying this ejection instability is investigated. Some gravitational effects can be theoretically treated by perturbation techniques on the axisymmetric base flow of the liquid metal. This leads to a modification of previously calculated critical current collector ejection values neglecting gravity effects. The derivation of the mathematical model which determines the perturbation of the liquid metal base flow due to gravitational effects is documented. Since gravity is a small force compared with the centrifugal effects, the base flow solutions can be expanded in inverse powers of the Froude number and modified liquid flow profiles can be determined as a function of the azimuthal angle. This model will be used in later work to theoretically study the effects of gravity on the ejection point of the current collector. A rederivation of the hydrodynamic instability threshold of a liquid metal current collector is presented.

Theoretical model of gravitational perturbation of current collector axisymmetric flow field

NASA Astrophysics Data System (ADS)

Walker, John S.; Brown, Samuel H.; Sondergaard, Neal A.

1990-05-01

Some designs of liquid-metal current collectors in homopolar motors and generators are essentially rotating liquid-metal fluids in cylindrical channels with free surfaces and will, at critical rotational speeds, become unstable. An investigation at David Taylor Research Center is being performed to understand the role of gravity in modifying this ejection instability. Some gravitational effects can be theoretically treated by perturbation techniques on the axisymmetric base flow of the liquid metal. This leads to a modification of previously calculated critical-current-collector ejection values neglecting gravity effects. The purpose of this paper is to document the derivation of the mathematical model which determines the perturbation of the liquid-metal base flow due to gravitational effects. Since gravity is a small force compared with the centrifugal effects, the base flow solutions can be expanded in inverse powers of the Froude number and modified liquid-flow profiles can be determined as a function of the azimuthal angle. This model will be used in later work to theoretically study the effects of gravity on the ejection point of the current collector.

Time-of-flight SIMS/MSRI reflectron mass analyzer and method

DOEpatents

Smentkowski, Vincent S.; Gruen, Dieter M.; Krauss, Alan R.; Schultz, J. Albert; Holecek, John C.

1999-12-28

A method and apparatus for analyzing the surface characteristics of a sample by Secondary Ion Mass Spectroscopy (SIMS) and Mass Spectroscopy of Recoiled Ions (MSRI) is provided. The method includes detecting back scattered primary ions, low energy ejected species, and high energy ejected species by ion beam surface analysis techniques comprising positioning a ToF SIMS/MSRI mass analyzer at a predetermined angle .theta., where .theta. is the angle between the horizontal axis of the mass analyzer and the undeflected primary ion beam line, and applying a specific voltage to the back ring of the analyzer. Preferably, .theta. is less than or equal to about 120.degree. and, more preferably, equal to 74.degree.. For positive ion analysis, the extractor, lens, and front ring of the reflectron are set at negative high voltages (-HV). The back ring of the reflectron is set at greater than about +700V for MSRI measurements and between the range of about +15 V and about +50V for SIMS measurements. The method further comprises inverting the polarity of the potentials applied to the extractor, lens, front ring, and back ring to obtain negative ion SIMS and/or MSRI data.

A faint type of supernova from a white dwarf with a helium-rich companion.

PubMed

Perets, H B; Gal-Yam, A; Mazzali, P A; Arnett, D; Kagan, D; Filippenko, A V; Li, W; Arcavi, I; Cenko, S B; Fox, D B; Leonard, D C; Moon, D-S; Sand, D J; Soderberg, A M; Anderson, J P; James, P A; Foley, R J; Ganeshalingam, M; Ofek, E O; Bildsten, L; Nelemans, G; Shen, K J; Weinberg, N N; Metzger, B D; Piro, A L; Quataert, E; Kiewe, M; Poznanski, D

2010-05-20

Supernovae are thought to arise from two different physical processes. The cores of massive, short-lived stars undergo gravitational core collapse and typically eject a few solar masses during their explosion. These are thought to appear as type Ib/c and type II supernovae, and are associated with young stellar populations. In contrast, the thermonuclear detonation of a carbon-oxygen white dwarf, whose mass approaches the Chandrasekhar limit, is thought to produce type Ia supernovae. Such supernovae are observed in both young and old stellar environments. Here we report a faint type Ib supernova, SN 2005E, in the halo of the nearby isolated galaxy, NGC 1032. The 'old' environment near the supernova location, and the very low derived ejected mass ( approximately 0.3 solar masses), argue strongly against a core-collapse origin. Spectroscopic observations and analysis reveal high ejecta velocities, dominated by helium-burning products, probably excluding this as a subluminous or a regular type Ia supernova. We conclude that it arises from a low-mass, old progenitor, likely to have been a helium-accreting white dwarf in a binary. The ejecta contain more calcium than observed in other types of supernovae and probably large amounts of radioactive (44)Ti.

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.

Development of a Comprehensive Neck Injury Criterion for Aircraft-Related Incidences

DTIC Science & Technology

1995-02-15

flight into ground because of distraction in cockpit. No attempt to eject, multiple extreme injuries. 38B 2 Multiple extreme FATAL; FATAL A-37B. Pilot...hypesthesia and hypalesthesia to the level of the lesion. (Reference 26) Pillar fracture A vertical fracture of the articular pillar (mass) resulting...from an Extension impaction of the involved mass by the ipsilateral superior (Hyperextension) articular mass during hyperextension and rotation. with

Cancellation of the central singularity of the Schwarzschild solution with natural mass inversion process

NASA Astrophysics Data System (ADS)

Petit, Jean-Pierre; D'Agostini, G.

2015-03-01

We reconsider the classical Schwarzschild solution in the context of a Janus cosmological model. We show that the central singularity can be eliminated through a simple coordinate change and that the subsequent transit from one fold to the other is accompanied by mass inversion. In such scenario matter swallowed by black holes could be ejected as invisible negative mass and dispersed in space.

An Unusual Coronal Mass Ejection: First Solar Wind Electron, Proton, Alpha Monitor (SWEPAM) Results from the Advanced Composition Explorer. Appendix 6

NASA Technical Reports Server (NTRS)

McComas, D. J.; Bame, S. J.; Barker, P. L.; Delapp, D. M.; Gosling, J. T.; Skoug, R. M.; Tokar, R. L.; Riley, P.; Feldman, W. C.; Santiago, E.

2001-01-01

This paper reports the first scientific results from the Solar Wind Electron Proton Alpha Monitor (SWEPAM) instrument on board the Advanced Composition Explorer (ACE) spacecraft. We analyzed a coronal mass ejection (CME) observed in the solar wind using data from early February, 1998. This event displayed several of the common signatures of CMEs, such as counterstreaming halo electrons and depressed ion and electron temperatures, as well as some unusual features. During a portion of the CME traversal, SWEPAM measured a very large helium to proton abundance ratio. Other heavy ions, with a set of ionization states consistent with normal (1 to 2x10(exp 6) K) coronal temperatures, were proportionately enhanced at this time. These observations suggest a source for at least some of the CME material, where heavy ions are initially concentrated relative to hydrogen and then accelerated up into the solar wind, independent of their mass and first ionization potential.

The Influence of Coronal Mass Ejections on the Mass-loss Rates of Hot-Jupiters

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

Cherenkov, A.; Bisikalo, D.; Fossati, L.

Hot-Jupiters are subject to extreme radiation and plasma flows coming from their host stars. Past ultraviolet Hubble Space Telescope observations, supported by hydrodynamic models, confirmed that these factors lead to the formation of an extended envelope, part of which lies beyond the Roche lobe. We use gas-dynamic simulations to study the impact of time variations in the parameters of the stellar wind, namely that of coronal mass ejections (CMEs), on the envelope of the typical hot-Jupiter HD 209458b. We consider three CMEs characterized by different velocities and densities, taking their parameters from typical CMEs observed for the Sun. The perturbationsmore » in the ram-pressure of the stellar wind during the passage of each CME tear off most of the envelope that is located beyond the Roche lobe. This leads to a substantial increase of the mass-loss rates during the interaction with the CME. We find that the mass lost by the planet during the whole crossing of a CME is of ≈10{sup 15} g, regardless of the CME taken into consideration. We also find that over the course of 1 Gyr, the mass lost by the planet because of CME impacts is comparable to that lost because of high-energy stellar irradiation.« less

RADIAL FLOW PATTERN OF A SLOW CORONAL MASS EJECTION

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

Feng, Li; Gan, Weiqun, E-mail: lfeng@pmo.ac.cn; Inhester, Bernd

2015-06-01

Height–time plots of the leading edge of coronal mass ejections (CMEs) have often been used to study CME kinematics. We propose a new method to analyze the CME kinematics in more detail by determining the radial mass transport process throughout the entire CME. Thus, our method is able to estimate not only the speed of the CME front but also the radial flow speed inside the CME. We have applied this method to a slow CME with an average leading edge speed of about 480 km s{sup −1}. In the Lagrangian frame, the speeds of the individual CME mass elementsmore » stay almost constant within 2 and 15 R{sub S}, the range over which we analyzed the CME. Hence, we have no evidence of net radial forces acting on parts of the CME in this range or of a pile up of mass ahead of the CME. We find evidence that the leading edge trajectory obtained by tie-pointing may gradually lag behind the Lagrangian front-side trajectories derived from our analysis. Our results also allow a much more precise estimate of the CME energy. Compared with conventional estimates using the CME total mass and leading edge motion, we find that the latter may overestimate the kinetic energy and the gravitational potential energy.« less

Space Weather Studies Using Ground-based Experimental Complex in Kazakhstan

NASA Astrophysics Data System (ADS)

Kryakunova, O.; Yakovets, A.; Monstein, C.; Nikolayevskiy, N.; Zhumabayev, B.; Gordienko, G.; Andreyev, A.; Malimbayev, A.; Levin, Yu.; Salikhov, N.; Sokolova, O.; Tsepakina, I.

2015-12-01

Kazakhstan ground-based experimental complex for space weather study is situated near Almaty. Results of space environment monitoring are accessible via Internet on the web-site of the Institute of Ionosphere (http://www.ionos.kz/?q=en/node/21) in real time. There is a complex database with hourly data of cosmic ray intensity, geomagnetic field intensity, and solar radio flux at 10.7 cm and 27.8 cm wavelengths. Several studies using those data are reported. They are an estimation of speed of a coronal mass ejection, a study of large scale traveling distrubances, an analysis of geomagnetically induced currents using the geomagnetic field data, and a solar energetic proton event on 27 January 2012.

Evidence for a current sheet forming in the wake of a coronal mass ejection from multi-viewpoint coronagraph observations

NASA Astrophysics Data System (ADS)

Patsourakos, S.; Vourlidas, A.

2011-01-01

Context. Ray-like features observed by coronagraphs in the wake of coronal mass ejections (CMEs) are sometimes interpreted as the white light counterparts of current sheets (CSs) produced by the eruption. The 3D geometry of these ray-like features is largely unknown and its knowledge should clarify their association to the CS and place constraints on CME physics and coronal conditions. Aims: If these rays are related to field relaxation behind CMEs, therefore representing current sheets, then they should be aligned to the CME axis. With this study we test these important implications for the first time. Methods: An example of such a post-CME ray was observed by various coronagraphs, including these of the Sun Earth Connection Coronal and Heliospheric investigation (SECCHI) onboard the Solar Terrestrial Relations Observatory (STEREO) twin spacecraft and the Large Angle Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO). The ray was observed in the aftermath of a CME which occurred on 9 April 2008. The twin STEREO spacecraft were separated by about 48° on that day. This significant separation combined with a third “eye” view supplied by LASCO allow for a truly multi-viewpoint observation of the ray and of the CME. We applied 3D forward geometrical modeling to the CME and to the ray as simultaneously viewed by SECCHI-A and B and by SECCHI-A and LASCO, respectively. Results: We found that the ray can be approximated by a rectangular slab, nearly aligned with the CME axis, and much smaller than the CME in both terms of thickness and depth (≈0.05 and 0.15 R⊙ respectively). The ray electron density and temperature were substantially higher than their values in the ambient corona. We found that the ray and CME are significantly displaced from the associated post-CME flaring loops. Conclusions: The properties and location of the ray are fully consistent with the expectations of the standard CME theories for post-CME current sheets. Therefore, our multi-viewpoint observations supply strong evidence that the observed post-CME ray is indeed related to a post-CME current sheet. Movies are only available in electronic form at http://www.aanda.org

The Genesis of an Impulsive Coronal Mass Ejection Observed at Ultra-High Cadence by AIA on SDO

DTIC Science & Technology

2010-04-01

Most CMEmodels agree that the final ejected structure is a magnetic fluxrope which may correspond to the cavity observed in 3-part CMEs in the outer ...signals the launch of an EUV wave around the bubble (movie1.mpg) but the wave analysis will be reported elsewhere. The outer rim of the bubble becomes...the upper section of the flux-rope and not to its legs. 2RHESSI was observing the Crab Nebula during our event. – 6 – SXR rise profile arises from the

Mass-loss Rates from Coronal Mass Ejections: A Predictive Theoretical Model for Solar-type Stars

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

Cranmer, Steven R.

Coronal mass ejections (CMEs) are eruptive events that cause a solar-type star to shed mass and magnetic flux. CMEs tend to occur together with flares, radio storms, and bursts of energetic particles. On the Sun, CME-related mass loss is roughly an order of magnitude less intense than that of the background solar wind. However, on other types of stars, CMEs have been proposed to carry away much more mass and energy than the time-steady wind. Earlier papers have used observed correlations between solar CMEs and flare energies, in combination with stellar flare observations, to estimate stellar CME rates. This papermore » sidesteps flares and attempts to calibrate a more fundamental correlation between surface-averaged magnetic fluxes and CME properties. For the Sun, there exists a power-law relationship between the magnetic filling factor and the CME kinetic energy flux, and it is generalized for use on other stars. An example prediction of the time evolution of wind/CME mass-loss rates for a solar-mass star is given. A key result is that for ages younger than about 1 Gyr (i.e., activity levels only slightly higher than the present-day Sun), the CME mass loss exceeds that of the time-steady wind. At younger ages, CMEs carry 10–100 times more mass than the wind, and such high rates may be powerful enough to dispel circumstellar disks and affect the habitability of nearby planets. The cumulative CME mass lost by the young Sun may have been as much as 1% of a solar mass.« less

Current sheet formation in a sheared force-free-magnetic field. [in sun

NASA Technical Reports Server (NTRS)

Wolfson, Richard

1989-01-01

This paper presents the results of a study showing how continuous shearing motion of magnetic footpoints in a tenuous, infinitely conducting plasma can lead to the development of current sheets, despite the absence of such sheets or even of neutral points in the initial state. The calculations discussed here verify the earlier suggestion by Low and Wolfson (1988) that extended current sheets should form due to the shearing of a force-free quadrupolar magnetic field. More generally, this work augments earlier studies suggesting that the appearance of discontinuities - current sheets - may be a necessary consequence of the topological invariance imposed on the magnetic field geometry of an ideal MHD system by virtue of its infinite conductivity. In the context of solar physics, the work shows how the gradual and continuous motion of magnetic footpoints at the solar photosphere may lead to the buildup of magnetic energy that can then be released explosively when finite conductivity effects become important and lead to the rapid dissipation of current sheets. Such energy release may be important in solar flares, coronal mass ejections, and other eruptive events.

Identification of microorganisms using superconducting tunnel junctions and time-of-flight mass spectrometry

NASA Astrophysics Data System (ADS)

Ullom, J. N.; Frank, M.; Horn, J. M.; Labov, S. E.; Langry, K.; Benner, W. H.

2000-04-01

We present time-of-flight measurements of biological material ejected from bacterial spores following laser irradiation. Ion impacts are registered on a microchannel plate detector and on a Superconducting Tunnel Junction (STJ) detector. We compare mass spectra obtained with the two detectors. The STJ has better sensitivity to massive ions and also measures the energy of each ion. We show evidence that spores of different bacillus species produce distinctive mass spectra and associate the observed mass peaks with coat proteins.

Trajectory analysis for the nucleus and dust of comet C/2013 A1 (Siding Spring)

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

Farnocchia, Davide; Chesley, Steven R.; Chodas, Paul W.

Comet C/2013 A1 (Siding Spring) will experience a high velocity encounter with Mars on 2014 October 19 at a distance of 135,000 km ± 5000 km from the planet center. We present a comprehensive analysis of the trajectory of both the comet nucleus and the dust tail. The nucleus of C/2013 A1 cannot impact on Mars even in the case of unexpectedly large nongravitational perturbations. Furthermore, we compute the required ejection velocities for the dust grains of the tail to reach Mars as a function of particle radius and density and heliocentric distance of the ejection. A comparison between ourmore » results and the most current modeling of the ejection velocities suggests that impacts are possible only for millimeter to centimeter size particles released more than 13 AU from the Sun. However, this level of cometary activity that far from the Sun is considered extremely unlikely. The arrival time of these particles spans a 20-minute time interval centered at 2014 October 19 at 20:09 TDB, i.e., around the time that Mars crosses the orbital plane of C/2013 A1. Ejection velocities larger than currently estimated by a factor >2 would allow impacts for smaller particles ejected as close as 3 AU from the Sun. These particles would reach Mars from 19:13 TDB to 20:40 TDB.« less

The solar cycle variation of coronal mass ejections and the solar wind mass flux

NASA Technical Reports Server (NTRS)

Webb, David F.; Howard, Russell A.

1994-01-01

Coronal mass ejections (CMEs) are an important aspect of coronal physics and a potentially significant contributor to perturbations of the solar wind, such as its mass flux. Sufficient data on CMEs are now available to permit study of their longer-term occurrency patterns. Here we present the results of a study of CME occurrence rates over more than a complete 11-year solar sunspot cycle and a comparison of these rates with those of other activity related to CMEs and with the solar wind particle flux at 1 AU. The study includes an evaluation of correlations to the CME rates, which include instrument duty cycles, visibility functions, mass detection thresholds, and geometrical considerations. The main results are as follows: (1) The frequency of occurrence of CMEs tends to track the solar activity cycle in both amplitude and phase; (2) the CME rates from different instruments, when corrected for both duty cycles and visibility functions, are reasonably consistent; (3) considering only longer-term averages, no one class of solar activity is better correlated with CME rate than any other; (4) the ratio of the annualized CME to solar wind mass flux tends to track the solar cycle; and (5) near solar maximum, CMEs can provide a significant fraction (i.e., approximately equals 15%) of the average mass flux to the near-ecliptic solar wind.

Accretion physics: It's not U, it's B

NASA Astrophysics Data System (ADS)

Miller, Jon

2017-03-01

Black holes grow by accreting mass, but the process is messy and redistributes gas and energy into their environments. New evidence shows that magnetic processes mediate both the accretion and ejection of matter.

Solar Eruptions: Coronal Mass Ejections and Flares

NASA Technical Reports Server (NTRS)

Gopalswamy, Nat

2012-01-01

This lecture introduces the topic of Coronal mass ejections (CMEs) and solar flares, collectively known as solar eruptions. During solar eruptions, the released energy flows out from the Sun in the form of magnetized plasma and electromagnetic radiation. The electromagnetic radiation suddenly increases the ionization content of the ionosphere, thus impacting communication and navigation systems. Flares can be eruptive or confined. Eruptive flares accompany CMEs, while confined flares hav only electromagnetic signature. CMEs can drive MHD shocks that accelerate charged particles to very high energies in the interplanetary space, which pose radiation hazard to astronauts and space systems. CMEs heading in the direction of Earth arrive in about two days and impact Earth's magnetosphere, producing geomagnetic storms. The magnetic storms result in a number of effects including induced currnts that can disrupt power grids, railroads, and underground pipelines

Enrichment of intergalactic matter.

NASA Technical Reports Server (NTRS)

Silk, J.; Siluk, R. S.

1972-01-01

The primordial gas out of which the Galaxy condensed may have been significantly enriched in heavy elements. A specific mechanism of enrichment is described, in which quasi-stellar sources eject enriched matter into the intergalactic medium. This matter is recycled through successive generations of these sources, and is progressively enriched. The enriched intergalactic matter is accreted by the protogalaxy and we find, for rates of mass ejection by quasi-stellar sources equal to about one solar mass per year in heavy elements, that this mechanism can account for the heavy-element abundances in the oldest Population II stars. Expressions are given for the degree of enrichment of the intergalactic gas as a function of redshift, and we show that our hypothesis implies that the present density of intergalactic gas must be at least a factor 3 larger than the mean density in galaxies at the present epoch.

Three-dimensional magnetic reconnection and the magnetic topology of coronal mass ejection events

NASA Technical Reports Server (NTRS)

Gosling, J. T.; Birn, J.; Hesse, M.

1995-01-01

Measurements of superthermal electron fluxes in the solar wind indicate that field lines within coronal mass ejections, CMEs, near and beyond 1 AU are normally connected to the Sun at both ends. However, on occasion some field lines embedded deep within CMEs appear to be connected to the Sun at only one end. Here we propose an explanation for how such field lines arise in terms of 3-dimensional reconnection close to the Sun. Such reconnection also provides a natural explanation for the flux rope topology characteristic of many CMEs as well as the coronal loops formed during long-duration, solar X-ray events. Our consideration of the field topologies resulting from 3-dimensional reconnection indicates that field lines within and near CMEs may on occasion be connected to the outer heliosphere at both ends.

Solar wind composition from sector boundary crossings and coronal mass ejections

NASA Technical Reports Server (NTRS)

Ogilvie, K. W.; Coplan, M. A.; Geiss, J.

1992-01-01

Using the Ion Composition Instrument (ICI) on board the ISEE-3/ICE spacecraft, average abundances of He-4, He-3, O, Ne, Si, and Fe have been determined over extended periods. In this paper the abundances of He-4, O, Ne, Si, and Mg obtained by the ICI in the region of sector boundary crossings (SBCs), magnetic clouds and bidirectional streaming events (BDSs) are compared with the average abundances. Both magnetic clouds and BDSs are associated with coronal mass ejections (CMEs). No variation of abundance is seen to occur at SBCs except for helium, as has already been observed. In CME-related material, the abundance of neon appears to be high and variable, in agreement with recent analysis of spectroscopic observations of active regions. We find that our observations can be correlated with the magnetic topology in the corona.

Global Acceleration of Coronal Mass Ejections

NASA Technical Reports Server (NTRS)

Gopalswamy, Nat; Lara, Alejandro; Lepping, Ronald; Kaiser, Michael; Berdichevsky, Daniel; St. Cyr, O. Chris; Lazarus, Al

1999-01-01

Using the observed relation between speeds of coronal mass ejections (CMEs) near the Sun and in the solar wind, we estimate a global acceleration acting on the CMEs. Our study quantifies the qualitative results of Gosling [1997] and numerical simulations that CMEs at 1 AU with speeds closer to the solar wind. We found a linear relation between the global acceleration and the initial speed of the CMEs and the absolute value of the acceleration is similar to the slow solar wind acceleration. Our study naturally divides CMEs into fast and slow ones, the dividing line being the solar wind speed. Our results have important implications to space weather prediction models which need to incorporate this effect in estimating the CME arrival time at 1 AU. We show that the arrival times of CMEs at 1 AU are drastically different from the zero acceleration case.

Origin of coronal mass ejection and magnetic cloud: Thermal or magnetic driven?

NASA Technical Reports Server (NTRS)

Zhang, Gong-Liang; Wang, Chi; He, Shuang-Hua

1995-01-01

A fundamental problem in Solar-Terrestrial Physics is the origin of the solar transient plasma output, which includes the coronal mass ejection and its interplanetary manifestation, e.g. the magnetic cloud. The traditional blast wave model resulted from solar thermal pressure impulse has faced with challenge during recent years. In the MHD numerical simulation study of CME, the authors find that the basic feature of the asymmetrical event on 18 August 1980 can be reproduced neither by a thermal pressure nor by a speed increment. Also, the thermal pressure model fails in simulating the interplanetary structure with low thermal pressure and strong magnetic field strength, representative of a typical magnetic cloud. Instead, the numerical simulation results are in favor of the magnetic field expansion as the likely mechanism for both the asymmetrical CME event and magnetic cloud.

Photospheric mass ejections caused by cometary impacts

NASA Astrophysics Data System (ADS)

Ibadov, Subhon; Ibodov, Firuz S.

It is analytically shown that impacts of cometary nuclei with the Sun will be accompanied, due to action of ram aerodynamic pressure at the passage of the high-velocity, more than 600 km/s, nucleus through the chromosphere by its crushing, lateral expansion of the crushed mass and sharp stopping of the flattening structure in a relatively very thin near-photosphere layer. High value of the specific kinetic energy of the comet nucleus, essentially more than the heat of its sublimation - of the order of 10^10 erg/g, leads to generation of a high-temperature, 10^6-10^7 K, plasma as well as strong "blast" shock wave in the decelerating layer, so that hot layer plasma will be ejected to the lower solar corona. Space observations of the phenomenon are of interest for revealing mechanisms for generation of solar prominences.

Mass ejections. [during solar flares

NASA Technical Reports Server (NTRS)

Rust, D. M.; Hildner, E.; Hansen, R. T.; Dryer, M.; Mcclymont, A. N.; Mckenna-Lawlor, S. M. P.; Mclean, D. J.; Schmahl, E. J.; Steinolfson, R. S.; Tandberg-Hanssen, E.

1980-01-01

Observations and model simulations of solar mass ejection phenomena are examined in an investigation of flare processes. Consideration is given to Skylab and other observations of flare-associated sprays, eruptive prominences, surges and coronal transients, and to MHD, gas dynamic and magnetic loop models developed to account for them. Magnetic forces are found to confine spray material, which originates in preexisting active-region filaments, within steadily expanding loops, while surges follow unmoving, preexisting magnetic field lines. Simulations of effects of a sudden pressure pulse at the bottom of the corona are found to exhibit many characteristics of coronal transients associated with flares, and impulsive heating low in the chromosphere is found to be able to account for surges. The importance of the magnetic field as the ultimate source of energy which drives eruptive phenomena as well as flares is pointed out.

A CORONAL HOLE'S EFFECTS ON CORONAL MASS EJECTION SHOCK MORPHOLOGY IN THE INNER HELIOSPHERE

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

Wood, B. E.; Wu, C.-C.; Howard, R. A.

2012-08-10

We use STEREO imagery to study the morphology of a shock driven by a fast coronal mass ejection (CME) launched from the Sun on 2011 March 7. The source region of the CME is located just to the east of a coronal hole. The CME ejecta is deflected away from the hole, in contrast with the shock, which readily expands into the fast outflow from the coronal hole. The result is a CME with ejecta not well centered within the shock surrounding it. The shock shape inferred from the imaging is compared with in situ data at 1 AU, wheremore » the shock is observed near Earth by the Wind spacecraft, and at STEREO-A. Shock normals computed from the in situ data are consistent with the shock morphology inferred from imaging.« less

Predicting the magnetic vectors within coronal mass ejections arriving at Earth: 1. Initial architecture

NASA Astrophysics Data System (ADS)

Savani, N. P.; Vourlidas, A.; Szabo, A.; Mays, M. L.; Richardson, I. G.; Thompson, B. J.; Pulkkinen, A.; Evans, R.; Nieves-Chinchilla, T.

2015-06-01

The process by which the Sun affects the terrestrial environment on short timescales is predominately driven by the amount of magnetic reconnection between the solar wind and Earth's magnetosphere. Reconnection occurs most efficiently when the solar wind magnetic field has a southward component. The most severe impacts are during the arrival of a coronal mass ejection (CME) when the magnetosphere is both compressed and magnetically connected to the heliospheric environment. Unfortunately, forecasting magnetic vectors within coronal mass ejections remain elusive. Here we report how, by combining a statistically robust helicity rule for a CME's solar origin with a simplified flux rope topology, the magnetic vectors within the Earth-directed segment of a CME can be predicted. In order to test the validity of this proof-of-concept architecture for estimating the magnetic vectors within CMEs, a total of eight CME events (between 2010 and 2014) have been investigated. With a focus on the large false alarm of January 2014, this work highlights the importance of including the early evolutionary effects of a CME for forecasting purposes. The angular rotation in the predicted magnetic field closely follows the broad rotational structure seen within the in situ data. This time-varying field estimate is implemented into a process to quantitatively predict a time-varying Kp index that is described in detail in paper II. Future statistical work, quantifying the uncertainties in this process, may improve the more heuristic approach used by early forecasting systems.

Runaway Massive Stars from R136: VFTS 682 is Very Likely a "Slow Runaway"

NASA Astrophysics Data System (ADS)

Banerjee, Sambaran; Kroupa, Pavel; Oh, Seungkyung

2012-02-01

We conduct a theoretical study on the ejection of runaway massive stars from R136—the central massive, starburst cluster in the 30 Doradus complex of the Large Magellanic Cloud. Specifically, we investigate the possibility of the very massive star (VMS) VFTS 682 being a runaway member of R136. Recent observations of the above VMS, by virtue of its isolated location and its moderate peculiar motion, have raised the fundamental question of whether isolated massive star formation is indeed possible. We perform the first realistic N-body computations of fully mass-segregated R136-type star clusters in which all the massive stars are in primordial binary systems. These calculations confirm that the dynamical ejection of a VMS from an R136-like cluster, with kinematic properties similar to those of VFTS 682, is common. Hence, the conjecture of isolated massive star formation is unnecessary to account for this VMS. Our results are also quite consistent with the ejection of 30 Dor 016, another suspected runaway VMS from R136. We further note that during the clusters' evolution, mergers of massive binaries produce a few single stars per cluster with masses significantly exceeding the canonical upper limit of 150 M ⊙. The observations of such single super-canonical stars in R136, therefore, do not imply an initial mass function with an upper limit greatly exceeding the accepted canonical 150 M ⊙ limit, as has been suggested recently, and they are consistent with the canonical upper limit.

Towards a General Equation for the Survival of Microbes Transferred between Solar System Bodies

NASA Technical Reports Server (NTRS)

Fries, M.; Steele, A.

2014-01-01

It should be possible to construct a general equation describing the survival of microbes transferred between Solar System bodies. Such an equation will be useful for constraining the likelihood of transfer of viable organisms between bodies throughout the lifetime of the Solar System, and for refining Planetary Protection constraints placed on future missions. We will discuss the construction of such an equation, present a plan for definition of pertinent factors, and will describe what research will be necessary to quantify those factors. Description: We will examine the case of microbes transferred between Solar System bodies as residents in meteorite material ejected from one body (the "intial body") and deposited on another (the "target body"). Any microbes transferred in this fashion will experience four distinct phases between their initial state on the initial body, up to the point where they colonize the target body. Each of these phases features phenomena capable of reducing or exterminating the initial microbial population. They are: 1) Ejection: Material is ejected from the initial body, imparting shock followed by rapid desiccation and cooling. 2) Transport: Material travels through interplanetary space to the target body, exposing a hypothetical microbial population to extended desiccation, irradiation, and temperature extremes. 3) Infall: Material is deposited on the target body, diminishing the microbial population through shock, mass loss, and heating. 4) Adaptation: Any microbes which survive the previous three phases must then adapt to new chemophysical conditions of the target body. Differences in habitability between the initial and target bodies dominate this phase. A suitable general-form equation can be assembled from the above factors by defining the initial number of microbes in an ejected mass and applying multiplicitive factors based on the physical phenomena inherent to each phase. It should be possible to present the resulting equation in terms of initial ejection mass, ejection shock magnitude, transfer time, initial microbial load and/or other terms and generate graphs defining the number of surviving microbes. The general form of the equation is: x(sub f) = x(sub i) f(sub1) f(sub 2) f(sub 3) f(sub 4) Where x(sub f) is the final number of microbes to survive transfer, x(sub i) is the initial population prior to ejection, and f(sub 1-4) are mortality factors for the four phases described above. Among other considerations, f(sub 1) will vary with respect to impact shock magnitude and f(sub 2) will be time-dependent. Considerable research has been performed to date to quantify the survival rates of various microbes in response to portions of these four phases, both as vegetative cells and/or spores. Results indicate that many species tend to respond differently to the pertinent mortality factors, especially in the case of extremophiles. Therefore, a complete equation will include species-specific responses to the mortality factors.

Biggest Solar Flare on Record

NASA Technical Reports Server (NTRS)

2002-01-01

View an animation from the Extreme ultraviolet Imaging Telescope (EIT). At 4:51 p.m. EDT, on Monday, April 2, 2001, the sun unleashed the biggest solar flare ever recorded, as observed by the Solar and Heliospheric Observatory (SOHO) satellite. The flare was definitely more powerful than the famous solar flare on March 6, 1989, which was related to the disruption of power grids in Canada. This recent explosion from the active region near the sun's northwest limb hurled a coronal mass ejection into space at a whopping speed of roughly 7.2 million kilometers per hour. Luckily, the flare was not aimed directly towards Earth. Solar flares, among the solar system's mightiest eruptions, are tremendous explosions in the atmosphere of the Sun capable of releasing as much energy as a billion megatons of TNT. Caused by the sudden release of magnetic energy, in just a few seconds flares can accelerate solar particles to very high velocities, almost to the speed of light, and heat solar material to tens of millions of degrees. Solar ejections are often associated with flares and sometimes occur shortly after the flare explosion. Coronal mass ejections are clouds of electrified, magnetic gas weighing billions of tons ejected from the Sun and hurled into space with speeds ranging from 12 to 1,250 miles per second. Depending on the orientation of the magnetic fields carried by the ejection cloud, Earth-directed coronal mass ejections cause magnetic storms by interacting with the Earth's magnetic field, distorting its shape, and accelerating electrically charged particles (electrons and atomic nuclei) trapped within. Severe solar weather is often heralded by dramatic auroral displays, northern and southern lights, and magnetic storms that occasionally affect satellites, radio communications and power systems. The flare and solar ejection has also generated a storm of high-velocity particles, and the number of particles with ten million electron-volts of energy in the space near Earth is now 10,000 times greater than normal. The increase of particles at this energy level still poses no appreciable hazard to air travelers, astronauts or satellites, and the NOAA SEC rates this radiation storm as a moderate S2 to S3, on a scale that goes to S5. Monday's solar flare produced an R4 radio blackout on the sunlit side of the Earth. An R4 blackout, rated by the NOAA SEC, is second to the most severe R5 classification. The classification measures the disruption in radio communications. X-ray and ultraviolet light from the flare changed the structure of the Earth's electrically charged upper atmosphere (ionosphere). This affected radio communication frequencies that either pass through the ionosphere to satellites or are reflected by it to traverse the globe. The SOHO mission is being conducted collaboratively between the European Space Agency and NASA. Images courtesy SOHO Project, NASA's Goddard Space Flight Center

Statistical study of coronal mass ejection source locations: Understanding CMEs viewed in coronagraphs

NASA Astrophysics Data System (ADS)

Wang, Yuming; Chen, Caixia; Gui, Bin; Shen, Chenglong; Ye, Pinzhong; Wang, S.

2011-04-01

How to properly understand coronal mass ejections (CMEs) viewed in white light coronagraphs is crucial to many relative researches in solar and space physics. The issue is now particularly addressed in this paper through studying the source locations of all the 1078 Large Angle and Spectrometric Coronagraph (LASCO) CMEs listed in Coordinated Data Analysis Workshop (CDAW) CME catalog during 1997-1998 and their correlation with CMEs' apparent parameters. By manually checking LASCO and Extreme Ultraviolet Imaging Telescope (EIT) movies of these CMEs, we find that, except 231 CMEs whose source locations cannot be identified due to poor data, there are 288 CMEs with location identified on the frontside solar disk, 234 CMEs appearing above solar limb, and 325 CMEs without evident eruptive signatures in the field of view of EIT. On the basis of the statistical results of CMEs' source locations, there are four physical issues: (1) the missing rate of CMEs by SOHO LASCO and EIT, (2) the mass of CMEs, (3) the causes of halo CMEs, and (4) the deflections of CMEs in the corona, are exhaustively analyzed. It is found that (1) about 32% frontside CMEs cannot be recognized by SOHO, (2) the brightness of a CME at any heliocentric distance is roughly positively correlated with its speed, and the CME mass derived from the brightness is probably overestimated, (3) both projection effect and violent eruption are the major causes of halo CMEs, and especially for limb halo CMEs the latter is the primary one, and (4) most CMEs deflected toward equator near the solar minimum; these deflections can be classified into three types: the asymmetrical expansion, the nonradial ejection, and the deflected propagation.

THE DUST ENVIRONMENT OF MAIN-BELT COMET P/2012 T1 (PANSTARRS)

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

Moreno, F.; Pozuelos, F.; Cabrera-Lavers, A.

2013-06-20

The Main-Belt Comet P/2012 T1 (PANSTARRS) has been imaged using the 10.4 m Gran Telescopio Canarias and the 4.2 m William Herschel Telescope at six epochs in the period from 2012 November to 2013 February, with the aim of monitoring its dust environment. The dust tails' brightness and morphology are best interpreted in terms of a model of sustained dust emission spanning four to six months. The total dust mass ejected is estimated at {approx}6-25 Multiplication-Sign 10{sup 6} kg. We assume a time-independent power-law size distribution function, with particles in the micrometer to centimeter size range. Based on the qualitymore » of the fits to the isophote fields, an anisotropic emission pattern is favored against an isotropic one, in which the particle ejection is concentrated toward high latitudes ({+-}45 Degree-Sign to {+-}90 Degree-Sign ) in a high-obliquity object (I = 80 Degree-Sign ). This seasonally driven ejection behavior, along with the modeled particle ejection velocities, are in remarkable agreement to those we found for P/2010 R2 (La Sagra).« less

Major Geomagnetic Storms (Dst less than or equal to -100 nT) Generated by Corotating Interaction Regions

NASA Technical Reports Server (NTRS)

Richardson, I. G.; Webb, D. F.; Zhang, J.; Berdichevsky, B. D.; Biesecker, D. A.; Kasper, J. C.; Kataoka, R.; Steinberg, J. T.; Thompson, B. J.; Wu, C.-C.;

The PIT MkV pulsed inductive thruster

NASA Technical Reports Server (NTRS)

Dailey, C. Lee; Lovberg, Ralph H.

1993-01-01

The pulsed inductive thruster (PIT) is an electrodeless, magnetic rocket engine that can operate with any gaseous propellant. A puff of gas injected against the face of a flat (spiral) coil is ionized and ejected by the magnetic field of a fast-rising current pulse from a capacitor bank discharge. Single shot operation on an impulse balance has provided efficiency and I(sub sp) data that characterize operation at any power level (pulse rate). The 1-m diameter MkV thruster concept offers low estimated engine mass at low powers, together with power capability up to more than 1 MW for the 1-m diameter design. A 20 kW design estimate indicates specific mass comparable to Ion Engine specific mass for 10,000 hour operation, while a 100,000 hour design would have a specific mass 1/3 that of the Ion Engine. Performance data are reported for ammonia and hydrazine. With ammonia, at 32 KV coil voltage, efficiency is a little more than 50 percent from 4000 to more than 8000 seconds I(sub sp). Comparison with data at 24 and 28 kV indicates that a wider I(sub sp) range could be achieved at higher coil voltages, if required for deep space missions.

Statistical Study of the Early Solar System's Instability with 4, 5 and 6 Giant Planets

NASA Astrophysics Data System (ADS)

Nesvorny, David; Morbidelli, A.

2012-10-01

Several properties of the Solar System, including the wide radial spacing and orbital eccentricities of giant planets, can be explained if the early Solar System evolved through a dynamical instability followed by migration of planets in the planetesimal disk. Here we report the results of a statistical study, in which we performed nearly ten thousand numerical simulations of planetary instability starting from hundreds of different initial conditions. We found that the dynamical evolution is typically too violent, if Jupiter and Saturn start in the 3:2 resonance, leading to ejection of least one ice giant from the Solar System. Planet ejection can be avoided if the mass of the transplanetary disk of planetesimals was large, but we found that a massive disk would lead to excessive dynamical damping, and to smooth migration that violates constraints from the survival of the terrestrial planets. Better results were obtained when the Solar System was assumed to have five giant planets initially and one ice giant, with the mass comparable to that of Uranus and Neptune, was ejected into interstellar space by Jupiter. The best results were obtained when the ejected planet was placed into the external 3:2 or 4:3 resonance with Saturn. The range of possible outcomes is rather broad in this case, indicating that the present Solar System is neither a typical nor expected result for a given initial state, and occurs, in best cases, with only a few percent probability. The case with six giant planets shows interesting dynamics but does offer significant advantages relative to the five planet case.

Two massive stars possibly ejected from NGC 3603 via a three-body encounter

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.; Kniazev, A. Y.; Chené, A.-N.; Schnurr, O.

2013-03-01

We report the discovery of a bow-shock-producing star in the vicinity of the young massive star cluster NGC 3603 using archival data of the Spitzer Space Telescope. Follow-up optical spectroscopy of this star with Gemini-South led to its classification as O6 V. The orientation of the bow shock and the distance to the star (based on its spectral type) suggest that the star was expelled from the cluster, while the young age of the cluster (˜2 Myr) implies that the ejection was caused by a dynamical few-body encounter in the cluster's core. The relative position on the sky of the O6 V star and a recently discovered O2 If*/WN6 star (located on the opposite side of NGC 3603) allows us to propose that both objects were ejected from the cluster via the same dynamical event - a three-body encounter between a single (O6 V) star and a massive binary (now the O2 If*/WN6 star). If our proposal is correct, then one can `weigh' the O2 If*/WN6 star using the conservation of the linear momentum. Given a mass of the O6 V star of ≈30 M⊙, we found that at the moment of ejection the mass of the O2 If*/WN6 star was ≈175 M⊙. Moreover, the observed X-ray luminosity of the O2 If*/WN6 star (typical of a single star) suggests that the components of this originally binary system have merged (e.g., because of encounter hardening).

Spectroscopic Observations of a Solar Flare and the Associated Coronal Mass Ejection

NASA Astrophysics Data System (ADS)

Murray, S.; Tian, H.; McKillop, S.

2013-12-01

We used data from the EUV Imaging Spectrometer (EIS) on board Hinode to examine a coronal mass ejection and a preceding flare observed on 21 November 2012 between 15:00 and 17:00 UT. Images from the Atmospheric Imaging Assembly on the Solar Dynamics Observatory were used to align the data from EIS with specific events occurring. We analyzed spectra of a few emission lines at three locations on the flare site and one location in the erupting prominence. On the flare site, we found line profiles showing typical characteristics of chromospheric evaporation: downflows at cooler lines and upflows at hotter lines. At one particular location on the flare site, we clearly identified dominant downflows on the order of 100 km/s in lines through Fe VIII to Fe XVI. To the best of our knowledge, this is the first time that such strong high-speed downflows have been spectroscopically observed in the impulsive phase of solar flares. The profile of the Fe VIII 184.54 line reveals two peaks and we were able to use the double Gaussian fit to separate the rapid downflows of dense material from the nearly stationary coronal background emission. For the erupting prominence, we were able to analyze multiple lines, cooler and warmer, of interest using this double Gaussian fit to separate the background emission from the emission of the ejected material. Our results show that the LOS velocities of the ejected material are about 100 km/s in the lower corona. Additionally, in each region of interest, we used the ratio of the density-sensitive line pair FeXII 195/186 to determine the electron density. Our results clearly show that the coronal densities were greatly enhanced during the flare. The density of the ejected material is also much larger than the typical coronal density. This research was supported by the NSF grant for the Solar Physics REU Program at the Smithsonian Astrophysical Observatory (AGS-1263241).

He, U, and Th Depth Profiling of Apatite and Zircon Using Laser Ablation Noble Gas Mass Spectrometry and SIMS

NASA Astrophysics Data System (ADS)

Monteleone, B. D.; van Soest, M. C.; Hodges, K. V.; Hervig, R.; Boyce, J. W.

2008-12-01

Conventional (U-Th)/He thermochronology utilizes single or multiple grain analyses of U- and Th-bearing minerals such as apatite and zircon and does not allow for assessment of spatial variation in concentration of He, U, or Th within individual crystals. As such, age calculation and interpretation require assumptions regarding 4He loss through alpha ejection, diffusive redistribution of 4He, and U and Th distribution as an initial condition for these processes. Although models have been developed to predict 4He diffusion parameters, correct for the effect of alpha ejection on calculated cooling ages, and account for the effect of U and Th zonation within apatite and zircon, measurements of 4He, U, and Th distribution have not been combined within a single crystal. We apply ArF excimer laser ablation, combined with noble gas mass spectrometry, to obtain depth profiles within apatite and zircon crystals in order to assess variations in 4He concentration with depth. Our initial results from pre-cut, pre-heated slabs of Durango apatite, each subjected to different T-t schedules, suggest a general agreement of 4He profiles with those predicted by theoretical diffusion models (Farley, 2000). Depth profiles through unpolished grains give reproducible alpha ejection profiles in Durango apatite that deviate from alpha ejection profiles predicted for ideal, homogenous crystals. SIMS depth profiling utilizes an O2 primary beam capable of sputtering tens of microns and measuring sub-micron resolution variation in [U], [Th], and [Sm]. Preliminary results suggest that sufficient [U] and [Th] zonation is present in Durango apatite to influence the form of the 4He alpha ejection profile. Future work will assess the influence of measured [U] and [Th] zonation on previously measured 4He depth profiles. Farley, K.A., 2000. Helium diffusion from apatite; general behavior as illustrated by Durango fluorapatite. J. Geophys. Res., B Solid Earth Planets 105 (2), 2903-2914.

Mass Loss from Stars: Prospects with ALMA and Other Radio Interferometers

NASA Astrophysics Data System (ADS)

Richards, Anita

2018-04-01

We can now fully resolve a small sample of stars, in general spotty and/or aspherical, with radii larger (as a function of observing wavelength) than the optical or NIR photosphere R*, requiring the full capabilities of ALMA, e-MERLIN, the NG-VLA or SKA with long baselines. ALMA results has confirmed the presence of continuum hot-spots as well as molecular absorption, against surpisingly large stellar diameters. These studies can be used to investigate the transport of mass and energy through the layers above the photosphere, timescales depending on whether radiative, ionisation/recombination effects, or bulk transport dominate. Maser properties can be measured with an order of magnitude higher resolutiong than thermal lines. The clumpiness of the wind could be related to local ejection of mass from the stellar surface. Models now provide the tools to reconstruct physical conditions from multiple maser lines, and could reveal changes associated with the formation of dust and the transition from complicated infall and outflow near the star, to the radially accelerating wind. I will concentrate on practical aspects of current and potential high-resolution observations to these ends.

Constraining the Statistics of Population III Binaries

NASA Technical Reports Server (NTRS)

Stacy, Athena; Bromm, Volker

2012-01-01

We perform a cosmological simulation in order to model the growth and evolution of Population III (Pop III) stellar systems in a range of host minihalo environments. A Pop III multiple system forms in each of the ten minihaloes, and the overall mass function is top-heavy compared to the currently observed initial mass function in the Milky Way. Using a sink particle to represent each growing protostar, we examine the binary characteristics of the multiple systems, resolving orbits on scales as small as 20 AU. We find a binary fraction of approx. 36, with semi-major axes as large as 3000 AU. The distribution of orbital periods is slightly peaked at approx. < 900 yr, while the distribution of mass ratios is relatively flat. Of all sink particles formed within the ten minihaloes, approx. 50 are lost to mergers with larger sinks, and 50 of the remaining sinks are ejected from their star-forming disks. The large binary fraction may have important implications for Pop III evolution and nucleosynthesis, as well as the final fate of the first stars.

Space Weather Impact on Pipeline in La Plata City, Argentine

NASA Astrophysics Data System (ADS)

Gianibelli, J. C.; Dovico, R. O.; Peirtti, R. O.; Pretel, R. O.; Garcia, R. E.; Quaglino, N. M.

2007-05-01

In the Sun-Earth connection, some of the most important characteristic events involved are the Coronal Mass Ejections (CME) and the high speed particle streams events coming from the Coronal Holes at the Sun. These interplanetary events produce effects on space and ground-based technology. In the present work, the geomagnetic storm recorded at Las Acacias Digital Magnetic Observatory (LAS, Lat.:-35º.0; Long.: 302º.3) produced by a particle stream from a solar coronal hole and their relationship with the induction effects caused on a pipeline in the shore of La Plata city, Argentine. The result shows an increase of the induced current correlated with the registered geomagnetic storm. Also, the magnetically calm days are analized. It is concluded that the amplitude of induced current intensity verifies a logarithmic relation with the amplitude of total magnetic intensity recorded in Las Acacias Observatory.

Plasmoids everywhere: ideal tearing, the transition to fast reconnection, and solar activity.

NASA Astrophysics Data System (ADS)

Velli, M. C. M.; Pucci, F.; Tenerani, A.; Shi, C.; Del Sarto, D.; Rappazzo, A. F.

2017-12-01

We discuss the role of generalized ``ideal" tearing (IT) as a possible trigger mechanism for magnetic reconnection to understand energetic phenomena in the solar atmosphere. We begin with a pedagogical introduction to the IT concept, how it stems from the classical analysis of the tearing instability, what is meant by plasmoids, and the connections of IT to the plasmoid instability and Sweet Parker current sheets. We then proceed to analyze how the IT concept extends to equilibria with flows, small scale kinetic effects, different current structures and different magnetic field topology configurations. Finally we discuss the relationship of reconnection triggering to nonlinear cascades and turbulent evolution, and how different situations may arise depending on scale, boundary conditions, and time-history, from coronal heating via nanoflares, to solar flares and coronal mass ejections. Issues of local topology, dimensionality, anisotropy will also be discussed.

Mass loss from solar-type stars

NASA Technical Reports Server (NTRS)

Hartmann, L.

1985-01-01

The present picture of mass loss from solar-type (low-mass) stars is described, with special emphasis on winds from pre-main-sequence stars. Attention is given to winds from T Tauri stars and to angular momentum loss. Prospects are good for further advances in our understanding of the powerful mass loss observed from young stars; ultraviolet spectra obtainable with the Space Telescope should provide better estimates of mass loss rates and a clearer picture of physical conditions in the envelopes of these stars. To understand the mass ejection from old, slowly rotating main-sequence stars, we will have to study the sun.

Small-scale filament eruptions as the driver of X-ray jets in solar coronal holes.

PubMed

Sterling, Alphonse C; Moore, Ronald L; Falconer, David A; Adams, Mitzi

2015-07-23

Solar X-ray jets are thought to be made by a burst of reconnection of closed magnetic field at the base of a jet with ambient open field. In the accepted version of the 'emerging-flux' model, such a reconnection occurs at a plasma current sheet between the open field and the emerging closed field, and also forms a localized X-ray brightening that is usually observed at the edge of the jet's base. Here we report high-resolution X-ray and extreme-ultraviolet observations of 20 randomly selected X-ray jets that form in coronal holes at the Sun's poles. In each jet, contrary to the emerging-flux model, a miniature version of the filament eruptions that initiate coronal mass ejections drives the jet-producing reconnection. The X-ray bright point occurs by reconnection of the 'legs' of the minifilament-carrying erupting closed field, analogous to the formation of solar flares in larger-scale eruptions. Previous observations have found that some jets are driven by base-field eruptions, but only one such study, of only one jet, provisionally questioned the emerging-flux model. Our observations support the view that solar filament eruptions are formed by a fundamental explosive magnetic process that occurs on a vast range of scales, from the biggest mass ejections and flare eruptions down to X-ray jets, and perhaps even down to smaller jets that may power coronal heating. A similar scenario has previously been suggested, but was inferred from different observations and based on a different origin of the erupting minifilament.

CMR reference values for left ventricular volumes, mass, and ejection fraction using computer-aided analysis: the Framingham Heart Study.

PubMed

Chuang, Michael L; Gona, Philimon; Hautvast, Gilion L T F; Salton, Carol J; Breeuwer, Marcel; O'Donnell, Christopher J; Manning, Warren J

2014-04-01

To determine sex-specific reference values for left ventricular (LV) volumes, mass, and ejection fraction (EF) in healthy adults using computer-aided analysis and to examine the effect of age on LV parameters. We examined data from 1494 members of the Framingham Heart Study Offspring cohort, obtained using short-axis stack cine SSFP CMR, identified a healthy reference group (without cardiovascular disease, hypertension, or LV wall motion abnormality) and determined sex-specific upper 95th percentile thresholds for LV volumes and mass, and lower 5th percentile thresholds for EF using computer-assisted border detection. In secondary analyses, we stratified participants by age-decade and tested for linear trend across age groups. The reference group comprised 685 adults (423F; 61 ± 9 years). Men had greater LV volumes and mass, before and after indexation to common measures of body size (all P = 0.001). Women had greater EF (73 ± 6 versus 71 ± 6%; P = 0.0002). LV volumes decreased with greater age in both sexes, even after indexation. Indexed LV mass did not vary with age. LV EF and concentricity increased with greater age in both sexes. We present CMR-derived LV reference values. There are significant age and sex differences in LV volumes, EF, and geometry, whereas mass differs between sexes but not age groups. Copyright © 2013 Wiley Periodicals, Inc.

CMR Reference Values for Left Ventricular Volumes, Mass and Ejection Fraction Using Computer-Aided Analysis: The Framingham Heart Study

PubMed Central

Chuang, Michael L.; Gona, Philimon; Hautvast, Gilion L.T.F.; Salton, Carol J.; Breeuwer, Marcel; O’Donnell, Christopher J.; Manning, Warren J.

2013-01-01

Purpose To determine sex-specific reference values for left ventricular (LV) volumes, mass and ejection fraction (EF) in healthy adults using computer-aided analysis and to examine the effect of age on LV parameters. Methods and Methods We examined data from 1494 members of the Framingham Heart Study Offspring cohort, obtained using short-axis stack cine SSFP CMR, identified a healthy reference group (without cardiovascular disease, hypertension, or LV wall motion abnormality) and determined sex-specific upper 95th percentile thresholds for LV volumes and mass, and lower 5th percentile thresholds for EF using computer-assisted border detection. In secondary analyses we stratified participants by age-decade and tested for linear trend across age groups. Results The reference group comprised 685 adults (423F; 61±9 years). Men had greater LV volumes and mass, before and after indexation to common measures of body size (all p<0.001). Women had greater EF (73±6 vs. 71±6%, p=0.0002). LV volumes decreased with greater age in both sexes, even after indexation. Indexed LV mass did not vary with age. LV EF and concentricity increased with greater age in both sexes. Conclusion We present CMR-derived LV reference values. There are significant age and sex differences in LV volumes, EF and geometry, while mass differs between sexes but not age groups. PMID:24123369

Molecular dynamics simulations of ejecta production from sinusoidal tin surfaces under supported and unsupported shocks

NASA Astrophysics Data System (ADS)

Wu, Bao; Wu, FengChao; Zhu, YinBo; Wang, Pei; He, AnMin; Wu, HengAn

2018-04-01

Micro-ejecta, an instability growth process, occurs at metal/vacuum or metal/gas interface when compressed shock wave releases from the free surface that contains surface defects. We present molecular dynamics (MD) simulations to investigate the ejecta production from tin surface shocked by supported and unsupported waves with pressures ranging from 8.5 to 60.8 GPa. It is found that the loading waveforms have little effect on spike velocity while remarkably affect the bubble velocity. The bubble velocity of unsupported shock loading remains nonzero constant value at late time as observed in experiments. Besides, the time evolution of ejected mass in the simulations is compared with the recently developed ejecta source model, indicating the suppressed ejection of unmelted or partial melted materials. Moreover, different reference positions are chosen to characterize the amount of ejecta under different loading waveforms. Compared with supported shock case, the ejected mass of unsupported shock case saturates at lower pressure. Through the analysis on unloading path, we find that the temperature of tin sample increases quickly from tensile stress state to zero pressure state, resulting in the melting of bulk tin under decaying shock. Thus, the unsupported wave loading exhibits a lower threshold pressure causing the solid-liquid phase transition on shock release than the supported shock loading.

Production of Star-Grazing and Star-Impacting Planetestimals via Orbital Migration of Extrasolar Planets

NASA Technical Reports Server (NTRS)

Quillen, A. C.; Holman, M.

2000-01-01

During the orbital migration of a giant extrasolar planet via ejection of planetesimals (as studied by Murray et al. in 1998), inner mean-motion resonances can be strong enough to cause planetesimals to graze or impact the star. We integrate numerically the motions of particles which pass through the 3:1 or 4:1 mean-motion resonances of a migrating Jupiter-mass planet. We find that many particles can be trapped in the 3:1 or 4:1 resonances and pumped to high enough eccentricities that they impact the star. This implies that for a planet migrating a substantial fraction of its semimajor axis, a fraction of its mass in planetesimals could impact the star. This process may be capable of enriching the metallicity of the star at a time when the star is no longer fully convective. Upon close approaches to the star, the surfaces of these planetesimals will be sublimated. Orbital migration should cause continuing production of evaporating bodies, suggesting that this process should be detectable with searches for transient absorption lines in young stars. The remainder of the particles will not impact the star but can be ejected subsequently by the planet as it migrates further inward. This allows the planet to migrate a substantial fraction of its initial semimajor axis by ejecting planetesimals.

Initiation of Coronal Mass Ejections by Tether-Cutting Reconnection

NASA Technical Reports Server (NTRS)

Moore, Ronald L.; Sterling, Alphonse C.; Falconer, David A.; Six, N. Frank (Technical Monitor)

2002-01-01

We present and interpret examples of the eruptive motion and flare brightening observed in the onset of magnetic explosions that produce coronal mass ejections. The observations are photospheric magnetograms and sequences of coronal and/or chromospheric images. In our examples, the explosion is apparently driven by the ejective eruption of a sigmoidal sheared-field flux rope from the core of an initially closed bipole. This eruption is initiated (triggered and unleashed) by reconnection located either (1) internally, low in the sheared core field, or (2) externally, at a magnetic null above the closed bipole. The internal reconnection is commonly called 'tether-cutting" reconnection, and the external reconnection is commonly called "break-out' reconnection. We point out that break-out reconnection amounts to external tether cutting. In one example, the eruptive motion of the sheared core field starts several minutes prior to any detectable brightening in the coronal images. We suggest that in this case the eruption is triggered by internal tether-cutting reconnection that at first is too slow and/or too localized to produce detectable heating in the coronal images. This work is supported by NASA's Office of Space Science through its Solar & Heliospheric Physics Supporting Research & Technology program and its Sun-Earth Connection Guest Investigator program.

Ejection of Particles from the Free Surface of Shock-Loaded Lead into Vacuum and Gas Medium

NASA Astrophysics Data System (ADS)

Ogorodnikov, V. A.; Mikhailov, A. L.; Erunov, S. V.; Antipov, M. V.; Fedorov, A. V.; Syrunin, M. A.; Kulakov, E. V.; Kleshchevnikov, O. A.; Yurtov, I. V.; Utenkov, A. A.; Finyushin, S. A.; Chudakov, E. A.; Kalashnikov, D. A.; Pupkov, A. S.; Chapaev, A. V.; Mishanov, A. V.; Glushikhin, V. V.; Fedoseev, A. V.; Tagirov, R. R.; Kostyukov, S. A.; Tagirova, I. Yu.; Saprykina, E. V.

2017-12-01

The presence and behavior of a gas-metal interfacial layer at the free surface of shock-wave driven flying vehicles in gases of various compositions and densities has not been sufficiently studied so far. We present new comparative data on "dusting" from the free surface of lead into vacuum and gas as dependent on the surface roughness, pressure amplitude at the shock-wave front, and phase state of the material. Methods of estimating the mass flux of ejected particles in the presence of a gas medium at the free metal surface are proposed.

Relativistic jets in SS 433

NASA Astrophysics Data System (ADS)

Margon, B.

1982-01-01

A variety of recent optical, radio, and X-ray observations have confirmed the hypothesis that the peculiar star SS 433 is ejecting two narrow, opposed, highly collimated jets of matter at one-quarter the speed of light. This unique behavior is probably driven by mass exchange between a relatively normal star and a compact companion, either a neutron star or a black hole. However, numerous details regarding the energetics, radiation, acceleration, and collimation of the jets remain to be understood. This phenomenon may well be a miniature example of similar collimated ejection of gas by active extragalactic objects such as quasars and radio galaxies.

Yield strength of Cu and an engineered material of Cu with 1% Pb

NASA Astrophysics Data System (ADS)

Buttler, William; Gray, George, III; Fensin, Saryu; Grover, Mike; Stevens, Gerald; Stone, Joseph; Turley, William

2015-06-01

To study the effects of engineered elastic-plastic yield on the mass-ejection from shocked materials we fielded explosively driven Cu and CuPb experiments. The Cu and CuPb experiments fielded fully annealed disks in contact with PBX 9501; the CuPb was extruded with 1% Pb that aggregates at the Cu grain boundaries. The elastic-plastic yield strength is explored as a difference of ejecta production of CuPb versus Cu, where the ejecta production of solid materials ties directly to the surface perturbation geometries of wavelengths (fixed at 65 μm) and amplitudes (which were varied). We observed that the Cu performs as expected, with ejecta turning on at the previously observed yield threshold, but the CuPb ejects mass in much larger quantities, at much lower wavenumber (k = 2 π/ λ) amplitude (h) products (kh), implying a reduced elastic-plastic yield stress of the engineered material, CuPb.

Energetic protons from a disappearing solar filament

NASA Technical Reports Server (NTRS)

Kahler, S. W.; Cliver, E. W.; Cane, H. V.; Mcguire, R. E.; Stone, R. G.; Sheeley, N. R., Jr.

1985-01-01

A solar energetic (E 50 MeV) particle (SEP) event observed at 1 AU began about 15000 UT on 1981 December 5. This event was associated with a fast coronal mass ejection observed with the Solwind coronagraph on the P78-1 satellite. No metric type 2 or type 4 burst was observed, but a weak interplanetary type 2 burst was observed with the low frequency radio experiment on the International Sun-Earth Explorer-3 satellite. The mass ejection was associated with the eruption of a large solar quiescent filament which lay well away from any active regions. The eruption resulted in an H alpha double ribbon structure which straddled the magnetic inversion line. No impulsive phase was obvious in either the H alpha or the microwave observations. This event indicates that neither a detectable impulsive phase nor a strong or complex magnetic field is necessary for the production of energetic ions.

Hypervelocity nanoparticle impacts on free-standing graphene: A sui generis mode of sputtering

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

Eller, Michael J.; Della-Negra, Serge; Liang, Chao-Kai

The study of the interaction of hypervelocity nano-particles with a 2D material and ultra-thin targets (single layer graphene, multi-layer graphene, and amorphous carbon foils) has been performed using mass selected gold nano-particles produced from a liquid metal ion source. During these impacts, a large number of atoms are ejected from the graphene, corresponding to a hole of ∼60 nm{sup 2}. Additionally, for the first time, secondary ions have been observed simultaneously in both the transmission and reflection direction (with respect to the path of the projectile) from a 2D target. The ejected area is much larger than that predicted bymore » molecular dynamic simulations and a large ionization rate is observed. The mass distribution and characteristics of the emitted secondary ions are presented and offer an insight into the process to produce the large hole observed in the graphene.« less

The Fraction of Interplanetary Coronal Mass Ejections That Are Magnetic Clouds: Evidence for a Solar Cycle Variation

NASA Technical Reports Server (NTRS)

Richardson, I. G.; Cane, H. V.

2004-01-01

"Magnetic clouds" (MCs) are a subset of interplanetary coronal mass ejections (ICMEs) characterized by enhanced magnetic fields with an organized rotation in direction, and low plasma beta. Though intensely studied, MCs only constitute a fraction of all the ICMEs that are detected in the solar wind. A comprehensive survey of ICMEs in the near- Earth solar wind during the ascending, maximum and early declining phases of solar cycle 23 in 1996 - 2003 shows that the MC fraction varies with the phase of the solar cycle, from approximately 100% (though with low statistics) at solar minimum to approximately 15% at solar maximum. A similar trend is evident in near-Earth observations during solar cycles 20 - 21, while Helios 1/2 spacecraft observations at 0.3 - 1.0 AU show a weaker trend and larger MC fraction.

The Strength and Radial Profile of the Coronal Magnetic Field from the Standoff Distance of a Coronal Mass Ejection-Driven Shock

NASA Technical Reports Server (NTRS)

Gopalswamy, Nat; Yashiro, Seiji

2011-01-01

We determine the coronal magnetic field strength in the heliocentric distance range 6-23 solar radii (Rs) by measuring the shock standoff distance and the radius of curvature of the flux rope during the 2008 March 25 coronal mass ejection imaged by white-light coronagraphs. Assuming the adiabatic index, we determine the Alfven Mach number, and hence the Alfven speed in the ambient medium using the measured shock speed. By measuring the upstream plasma density using polarization brightness images, we finally get the magnetic field strength upstream of the shock. The estimated magnetic field decreases from approximately 48 mG around 6 Rs to 8 mG at 23 Rs. The radial profile of the magnetic field can be described by a power law in agreement with other estimates at similar heliocentric distances.

MAVEN observations of the response of Mars to an interplanetary coronal mass ejection.

PubMed

Jakosky, B M; Grebowsky, J M; Luhmann, J G; Connerney, J; Eparvier, F; Ergun, R; Halekas, J; Larson, D; Mahaffy, P; McFadden, J; Mitchell, D F; Schneider, N; Zurek, R; Bougher, S; Brain, D; Ma, Y J; Mazelle, C; Andersson, L; Andrews, D; Baird, D; Baker, D; Bell, J M; Benna, M; Chaffin, M; Chamberlin, P; Chaufray, Y-Y; Clarke, J; Collinson, G; Combi, M; Crary, F; Cravens, T; Crismani, M; Curry, S; Curtis, D; Deighan, J; Delory, G; Dewey, R; DiBraccio, G; Dong, C; Dong, Y; Dunn, P; Elrod, M; England, S; Eriksson, A; Espley, J; Evans, S; Fang, X; Fillingim, M; Fortier, K; Fowler, C M; Fox, J; Gröller, H; Guzewich, S; Hara, T; Harada, Y; Holsclaw, G; Jain, S K; Jolitz, R; Leblanc, F; Lee, C O; Lee, Y; Lefevre, F; Lillis, R; Livi, R; Lo, D; Mayyasi, M; McClintock, W; McEnulty, T; Modolo, R; Montmessin, F; Morooka, M; Nagy, A; Olsen, K; Peterson, W; Rahmati, A; Ruhunusiri, S; Russell, C T; Sakai, S; Sauvaud, J-A; Seki, K; Steckiewicz, M; Stevens, M; Stewart, A I F; Stiepen, A; Stone, S; Tenishev, V; Thiemann, E; Tolson, R; Toublanc, D; Vogt, M; Weber, T; Withers, P; Woods, T; Yelle, R

2015-11-06

Coupling between the lower and upper atmosphere, combined with loss of gas from the upper atmosphere to space, likely contributed to the thin, cold, dry atmosphere of modern Mars. To help understand ongoing ion loss to space, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made comprehensive measurements of the Mars upper atmosphere, ionosphere, and interactions with the Sun and solar wind during an interplanetary coronal mass ejection impact in March 2015. Responses include changes in the bow shock and magnetosheath, formation of widespread diffuse aurora, and enhancement of pick-up ions. Observations and models both show an enhancement in escape rate of ions to space during the event. Ion loss during solar events early in Mars history may have been a major contributor to the long-term evolution of the Mars atmosphere. Copyright © 2015, American Association for the Advancement of Science.

Testing the reliability of ice-cream cone model

NASA Astrophysics Data System (ADS)

Pan, Zonghao; Shen, Chenglong; Wang, Chuanbing; Liu, Kai; Xue, Xianghui; Wang, Yuming; Wang, Shui

2015-04-01

Coronal Mass Ejections (CME)'s properties are important to not only the physical scene itself but space-weather prediction. Several models (such as cone model, GCS model, and so on) have been raised to get rid of the projection effects within the properties observed by spacecraft. According to SOHO/ LASCO observations, we obtain the 'real' 3D parameters of all the FFHCMEs (front-side full halo Coronal Mass Ejections) within the 24th solar cycle till July 2012, by the ice-cream cone model. Considering that the method to obtain 3D parameters from the CME observations by multi-satellite and multi-angle has higher accuracy, we use the GCS model to obtain the real propagation parameters of these CMEs in 3D space and compare the results with which by ice-cream cone model. Then we could discuss the reliability of the ice-cream cone model.

Testing the reliability of ice-cream cone model

NASA Astrophysics Data System (ADS)

Pan, Z.; Shen, C.; Wang, Y.; Liu, K.

2013-12-01

Coronal Mass Ejections (CME)'s properties are important to not only the physical scene itself but spaceweather prediction. Several models(such as cone model, GCS model, and so on) have been raised to get rid of the projection effects within the properties observated by spacecraft. According to SOHO/ LASCO observations, we obtain the 'real' 3D parameters of 33 FFHCMEs (front-side full halo Coronal Mass Ejections) within the 24th solar cycle by the ice-cream cone model. Considering that the method to obtain 3D parameters from the CME observations by multi-satellite and multi-angle has higher accuracy, we use the GCS model to obtain the real propagation parameters of these CMEs in 3D space and compare the results with which by ice-cream cone model. It was demonstrated that the correlation coefficient for the speeds by using these both methods is 0.97.

Geometrical Properties of Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Cremades, Hebe; Bothmer, Volker

Based on the SOHO/LASCO dataset, a collection of "structured" coronal mass ejections (CMEs) has been compiled within the period 1996-2002, in order to analyze their three-dimensional configuration. These CME events exhibit white-light fine structures, likely indicative of their possible 3D topology. From a detailed investigation of the associated low coronal and photospheric source regions, a generic scheme has been deduced, which considers the white-light topology of a CME projected in the plane of the sky as being primarily dependent on the orientation and position of the source region's neutral line on the solar disk. The obtained results imply that structured CMEs are essentially organized along a symmetry axis, in a cylindrical manner. The measured dimensions of the cylinder's base and length yield a ratio of 1.6. These CMEs seem to be better approximated by elliptic cones, rather than by the classical ice cream cone, characterized by a circular cross section.

ON THE ENHANCED CORONAL MASS EJECTION DETECTION RATE SINCE THE SOLAR CYCLE 23 POLAR FIELD REVERSAL

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

Petrie, G. J. D.

2015-10-10

Compared to cycle 23, coronal mass ejections (CMEs) with angular widths >30° have been observed to occur at a higher rate during solar cycle 24, per sunspot number. This result is supported by data from three independent databases constructed using Large Angle and Spectrometric Coronagraph Experiment coronagraph images, two employing automated detection techniques and one compiled manually by human observers. According to the two databases that cover a larger field of view, the enhanced CME rate actually began shortly after the cycle 23 polar field reversal, in 2004, when the polar fields returned with a 40% reduction in strength andmore » the interplanetary radial magnetic field became ≈30% weaker. This result is consistent with the link between anomalous CME expansion and the heliospheric total pressure decrease recently reported by Gopalswamy et al.« less

Mass loss from the region of Mars and the asteroid belt

NASA Technical Reports Server (NTRS)

Weidenschilling, S. J.

1975-01-01

Models of the solar nebula suggest that the mass of solid matter which condensed in the region of Mars and the asteroids was much greater than the amount now present. Bombardment by a primordial population of asteroidal bodies originating near Jupiter's orbit could preferentially remove matter from this region, without significant effects in the earth's zone. A critical velocity exists, for which they can be ejected from the solar system by Jupiter. The minimum perihelion attainable at this velocity lies between the orbits of Mars and the earth. The lifetimes of Mars-crossing bodies are limited by collisions with Jupiter; earth-crossers are ejected on a much shorter time scale. The total bombardment flux was at least two orders of magnitude greater in the zone of Mars than in that of the earth. The flux at Venus and Mercury from this source was negligible.

On the formation of runaway stars BN and x in the Orion Nebula Cluster

NASA Astrophysics Data System (ADS)

Farias, J. P.; Tan, J. C.

2018-05-01

We explore scenarios for the dynamical ejection of stars BN and x from source I in the Kleinmann-Low nebula of the Orion Nebula Cluster (ONC), which is important because it is the closest region of massive star formation. This ejection would cause source I to become a close binary or a merger product of two stars. We thus consider binary-binary encounters as the mechanism to produce this event. By running a large suite of N-body simulations, we find that it is nearly impossible to match the observations when using the commonly adopted masses for the participants, especially a source I mass of 7 M⊙. The only way to recreate the event is if source I is more massive, that is, 20 M⊙. However, even in this case, the likelihood of reproducing the observed system is low. We discuss the implications of these results for understanding this important star-forming region.

Anomalous Expansion of Coronal Mass Ejections During Solar Cycle 24 and Its Space Weather Implications

NASA Technical Reports Server (NTRS)

Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Xie, Hong; Makela, Pertti; Michalek, Grzegorz

2014-01-01

The familiar correlation between the speed and angular width of coronal mass ejections (CMEs) is also found in solar cycle 24, but the regression line has a larger slope: for a given CME speed, cycle 24 CMEs are significantly wider than those in cycle 23. The slope change indicates a significant change in the physical state of the heliosphere, due to the weak solar activity. The total pressure in the heliosphere (magnetic + plasma) is reduced by approximately 40%, which leads to the anomalous expansion of CMEs explaining the increased slope. The excess CME expansion contributes to the diminished effectiveness of CMEs in producing magnetic storms during cycle 24, both because the magnetic content of the CMEs is diluted and also because of the weaker ambient fields. The reduced magnetic field in the heliosphere may contribute to the lack of solar energetic particles accelerated to very high energies during this cycle.

υ-driven winds from the remnant of binary neutron star mergers

NASA Astrophysics Data System (ADS)

Perego, A.

2018-01-01

We present a 3D hydrodynamic study of the neutrino-driven winds that emerge from the remnant of a neutron star merger, represented by a thick accretion disc orbiting around a massive neutron star. This strong baryonic wind is blown out by neutrino absorption on free baryons inside the disc. It expands within a few tens of ms along the original binary rotation axis. If the central object survives for at least 200ms, the mass ejected in the wind can reach 5% of the initial mass of the accretion disc. Due to the intense neutrino irradiation, matter ejected in the wind increases its electron fraction between 0.3 and 0.4, producing weak r-process nucleosynthesis yields. We predict a distinct UV/optical transient associated with the wind ejecta that peaks from a few hours to a few days after the merger.

A CATALOG OF SOLAR X-RAY PLASMA EJECTIONS OBSERVED BY THE SOFT X-RAY TELESCOPE ON BOARD YOHKOH

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

Tomczak, M.; Chmielewska, E., E-mail: tomczak@astro.uni.wroc.pl, E-mail: chmielewska@astro.uni.wroc.pl

2012-03-01

A catalog of X-ray plasma ejections (XPEs) observed by the Soft X-ray Telescope on board the Yohkoh satellite has been recently developed in the Astronomical Institute of University of Wroclaw. The catalog contains records of 368 events observed in years 1991-2001 including movies and cross-references to associated events like flares and coronal mass ejections (CMEs). One hundred sixty-three XPEs out of 368 in the catalog were not reported until now. A new classification scheme of XPEs is proposed in which morphology, kinematics, and recurrence are considered. The relation between individual subclasses of XPEs and the associated events was investigated. Themore » results confirm that XPEs are strongly inhomogeneous, responding to different processes that occur in the solar corona. A subclass of erupting loop-like XPEs is a promising candidate to be a high-temperature precursor of CMEs.« less

Measurement of whole-body human centers of gravity and moments of inertia.

PubMed

Albery, C B; Schultz, R B; Bjorn, V S

1998-06-01

With the inclusion of women in combat aircraft, the question of safe ejection seat operation has been raised. The potential expanded population of combat pilots would include both smaller and larger ejection seat occupants, which could significantly affect seat performance. The method developed to measure human whole-body CG and MOI used a scale, a knife edge balance, and an inverted torsional pendulum. Subjects' moments of inertia were measured along six different axes. The inertia tensor was calculated from these values, and principal moments of inertia were then derived. Thirty-eight antropometric measurements were also taken for each subject to provide a means for direct correlation of inertial properties to body dimensions and for modeling purposes. Data collected in this study has been used to validate whole-body mass properties predictions. In addition, data will be used to improve Air Force and Navy ejection seat trajectory models for the expanded population.

An analytical study of the effect of airplane wake on the lateral dispersion of aerial sprays

NASA Technical Reports Server (NTRS)

Reed, Wilmer H , III

1954-01-01

Calculations are made to determine the trajectories of liquid droplets introduced into the air disturbances generated by an airplane engaged in aerial spraying. The effects of such factors as the positions at which droplets are ejected into the disturbances, airplane lift coefficient, and altitude are investigated. The distribution of deposit on the ground is computed for several droplet-size spectra, variations in the rate at which mass is ejected along the span, and lateral flight-path spacings. Consideration is then given to the problem of adjusting these factors with the aim of improving the uniformity and increasing the effective width of the deposit. The results indicate that the lateral dispersion of droplets is increased when the spanwise position at which particles are ejected is moved toward the wing tip. Greater dispersion also results when the airplane lift coefficient or altitude is increased.

Flares, ejections, proton events

NASA Astrophysics Data System (ADS)

Belov, A. V.

2017-11-01

Statistical analysis is performed for the relationship of coronal mass ejections (CMEs) and X-ray flares with the fluxes of solar protons with energies >10 and >100 MeV observed near the Earth. The basis for this analysis was the events that took place in 1976-2015, for which there are reliable observations of X-ray flares on GOES satellites and CME observations with SOHO/LASCO coronagraphs. A fairly good correlation has been revealed between the magnitude of proton enhancements and the power and duration of flares, as well as the initial CME speed. The statistics do not give a clear advantage either to CMEs or the flares concerning their relation with proton events, but the characteristics of the flares and ejections complement each other well and are reasonable to use together in the forecast models. Numerical dependences are obtained that allow estimation of the proton fluxes to the Earth expected from solar observations; possibilities for improving the model are discussed.

Ejection of sodium from sodium sulfide by the sputtering of the surface of Io

NASA Technical Reports Server (NTRS)

Chrisey, D. B.; Johnson, R. E.; Boring, J. W.; Phipps, J. A.

1988-01-01

The mechanism by which Na is removed from the surface of Io prior to its injection into the plasma torus is investigated experimentally. Na2S films of thickness 3-8 microns were produced by spray coating an Ni substrate in a dry N2 atmosphere and subjected to sputtering by 34-keV Ar(+), Ne(+), Kr(+), or Xe(+) ions up to total doses of about 5 x 10 to the 18th ions/sq cm. The sputtering yields and mass spectra are found to be consistent with ejection of only small amounts of atomic Na and somewhat larger amounts of Na-containing molecules. It is concluded that the amount of Na ejected by magnetospheric-ion sputtering of Na2S would be insufficient to account for the amounts observed in the Io neutral cloud. A scenario involving sputtering of larger polysulfide molecules is considered.

Genesis of Interplanetary Intermittent Turbulence: a Case Study of Rope-Rope Magnetic Reconnection

NASA Technical Reports Server (NTRS)

Chian, Abraham C.- L.; Feng, Heng Q.; Hu, Qiang; Loew, Murray H.; Miranda, Rodrigo A.; Munoz, Pablo R.; Sibeck, David G.; Wu, De J.

2016-01-01

In a recent paper, the relation between current sheet, magnetic reconnection, and turbulence at the leading edge of an interplanetary coronal mass ejection was studied. We report here the observation of magnetic reconnection at the interface region of two interplanetary magnetic flux ropes. The front and rear boundary layers of three interplanetary magnetic flux ropes are identified, and the structures of magnetic flux ropes are reconstructed by the Grad Shafranov method. A quantitative analysis of the reconnection condition and the degree of intermittency reveals that rope-rope magnetic reconnection is the most likely site for genesis of interplanetary intermittency turbulence in this event. The dynamic pressure pulse resulting from this reconnection triggers the onset of a geomagnetic storm.

Modeling Magnetic Flux-Ropes Structures

NASA Astrophysics Data System (ADS)

Nieves-Chinchilla, T.; Linton, M.; Hidalgo, M. A. U.; Vourlidas, A.; Savani, N.; Szabo, A.; Farrugia, C. J.; Yu, W.

2015-12-01

Flux-ropes are usually associated with magnetic structures embedded in the interplanetary Coronal Mass Ejections (ICMEs) with a depressed proton temperature (called Magnetic Clouds, MCs). However, small-scale flux-ropes in the solar wind are also identified with different formation, evolution, and dynamic involved. We present an analytical model to describe magnetic flux-rope topologies. The model is generalized to different grades of complexity. It extends the circular-cylindrical concept of Hidalgo et al. (2002) by introducing a general form for the radial dependence of the current density. This generalization provides information on the force distribution inside the flux rope in addition to the usual parameters of flux-rope geometrical information and orientation. The generalized model provides flexibility for implementation in 3-D MHD simulations.

Laser experiments to simulate coronal mass ejection driven magnetospheres and astrophysical plasma winds on compact magnetized stars

NASA Astrophysics Data System (ADS)

Horton, W.; Ditmire, T.; Zakharov, Yu. P.

2010-06-01

Laboratory experiments using a plasma wind generated by laser-target interaction are proposed to investigate the creation of a shock in front of the magnetosphere and the dynamo mechanism for creating plasma currents and voltages. Preliminary experiments are shown where measurements of the electron density gradients surrounding the obstacles are recorded to infer the plasma winds. The proposed experiments are relevant to understanding the electron acceleration mechanisms taking place in shock-driven magnetic dipole confined plasmas surrounding compact magnetized stars and planets. Exploratory experiments have been published [P. Brady, T. Ditmire, W. Horton, et al., Phys. Plasmas 16, 043112 (2009)] with the one Joule Yoga laser and centimeter sized permanent magnets.

Right ventricular strain in heart failure: Clinical perspective.

PubMed

Tadic, Marijana; Pieske-Kraigher, Elisabeth; Cuspidi, Cesare; Morris, Daniel A; Burkhardt, Franziska; Baudisch, Ana; Haßfeld, Sabine; Tschöpe, Carsten; Pieske, Burket

2017-10-01

The number of studies demonstrating the importance of right ventricular remodelling in a wide range of cardiovascular diseases has increased in the past two decades. Speckle-tracking imaging provides new variables that give comprehensive information about right ventricular function and mechanics. In this review, we summarize current knowledge of right ventricular mechanics in heart failure with reduced ejection fraction and preserved ejection fraction. We searched PubMed, MEDLINE, Ovid and Embase databases for studies published from January 2000 to December 2016 in the English language using the following keywords: "right ventricle"; "strain"; "speckle tracking"; "heart failure with reduced ejection fraction"; and "heart failure with preserved ejection fraction". Investigations showed that right ventricular dysfunction is associated with higher cardiovascular and overall mortality in patients with heart failure, irrespective of ejection fraction. The number of studies investigating right ventricular strain in patients with heart failure with reduced ejection fraction is constantly increasing, whereas data on right ventricular mechanics in patients with heart failure with preserved ejection fraction are limited. Given the high feasibility, accuracy and clinical implications of right ventricular strain in the population with heart failure, it is of great importance to try to include the evaluation of right ventricular strain as a regular part of each echocardiographic examination in patients with heart failure. However, further investigations are necessary to establish right ventricular strain as a standard variable for decision-making. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

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

Jordanova, Vania K

Understanding the response at Earth of the Sun's varying energy output and forecasting geomagnetic activity is of central interest to space science, since intense geomagnetic storms may cause severe damages on technological systems and affect communications. Episodes of southward (Bz

Solar events and their influence on the interplanetary medium

NASA Technical Reports Server (NTRS)

Joselyn, Joann

1987-01-01

Aspects of a workshop on Solar events and their influence on the interplanetary medium, held in September 1986, are reviewed, the goal of which was to foster interactions among colleagues, leading to an improved understanding of the unified relationship between solar events and interplanetary disturbances. The workshop consisted of three working groups: (1) flares, eruptives, and other near-Sun activity; (2) coronal mass ejections; and (3) interplanetary events. Each group discussed topics distributed in advance. The flares-eruptives group members agreed that pre-event energy is stored in stressed/sheared magnetic fields, but could not agree that flares and other eruptive events (e.g., eruptive solar prominences) are aspects of the same physical phenomenon. In the coronal mass ejection group, general agreement was reached on the presence of prominences in CMEs, and that they have a significant three-dimensional structure. Some topics identified for further research were the aftermath of CMEs (streamer deflections, transient coronal holes, possible disconnections), identification of the leading edge of CMEs, and studies of the range and prevalence of CME mass sizes and energies.

Modeling Volcanic Eruption Parameters by Near-Source Internal Gravity Waves.

PubMed

Ripepe, M; Barfucci, G; De Angelis, S; Delle Donne, D; Lacanna, G; Marchetti, E

2016-11-10

Volcanic explosions release large amounts of hot gas and ash into the atmosphere to form plumes rising several kilometers above eruptive vents, which can pose serious risk on human health and aviation also at several thousands of kilometers from the volcanic source. However the most sophisticate atmospheric models and eruptive plume dynamics require input parameters such as duration of the ejection phase and total mass erupted to constrain the quantity of ash dispersed in the atmosphere and to efficiently evaluate the related hazard. The sudden ejection of this large quantity of ash can perturb the equilibrium of the whole atmosphere triggering oscillations well below the frequencies of acoustic waves, down to much longer periods typical of gravity waves. We show that atmospheric gravity oscillations induced by volcanic eruptions and recorded by pressure sensors can be modeled as a compact source representing the rate of erupted volcanic mass. We demonstrate the feasibility of using gravity waves to derive eruption source parameters such as duration of the injection and total erupted mass with direct application in constraining plume and ash dispersal models.

Modeling Volcanic Eruption Parameters by Near-Source Internal Gravity Waves

PubMed Central

Ripepe, M.; Barfucci, G.; De Angelis, S.; Delle Donne, D.; Lacanna, G.; Marchetti, E.

2016-01-01

Volcanic explosions release large amounts of hot gas and ash into the atmosphere to form plumes rising several kilometers above eruptive vents, which can pose serious risk on human health and aviation also at several thousands of kilometers from the volcanic source. However the most sophisticate atmospheric models and eruptive plume dynamics require input parameters such as duration of the ejection phase and total mass erupted to constrain the quantity of ash dispersed in the atmosphere and to efficiently evaluate the related hazard. The sudden ejection of this large quantity of ash can perturb the equilibrium of the whole atmosphere triggering oscillations well below the frequencies of acoustic waves, down to much longer periods typical of gravity waves. We show that atmospheric gravity oscillations induced by volcanic eruptions and recorded by pressure sensors can be modeled as a compact source representing the rate of erupted volcanic mass. We demonstrate the feasibility of using gravity waves to derive eruption source parameters such as duration of the injection and total erupted mass with direct application in constraining plume and ash dispersal models. PMID:27830768

High-mass heterogeneous cluster formation by ion bombardment of the ternary alloy Au 7Cu 5Al 4

DOE PAGES

Zinovev, Alexander V.; King, Bruce V.; Veryovkin, Igor V.; ...

2016-02-04

The ternary alloy Au 7Cu 5Al 4 was irradiated with 0.1–10 keV Ar + and the surface composition analyzed using laser sputter neutral mass spectrometry. Ejected clusters containing up to seven atoms, with masses up to 2000 amu, were observed. By monitoring the signals from sputtered clusters, the surface composition of the alloy was seen to change with 100 eV Ar + dose, reaching equilibrium after 10 nm of the surface was eroded, in agreement with TRIDYN simulation and indicating that the changes were due to preferential sputtering of Al and Cu. Ejected gold containing clusters were found to increasemore » markedly in intensity while aluminum containing clusters decreased in intensity as a result of Ar sputtering. Such an effect was most pronounced for low energy (<1 keV) Ar + sputtering and was consistent with TRIDYN simulations of the depth profiling. As a result, the component sputter yields from the ternary alloy were consistent with previous binary alloy measurements but showed greater Cu surface concentrations than expected from TRIDYN simulations.« less

Low-mass X-ray binaries from black hole retaining globular clusters

NASA Astrophysics Data System (ADS)

Giesler, Matthew; Clausen, Drew; Ott, Christian D.

2018-06-01

Recent studies suggest that globular clusters (GCs) may retain a substantial population of stellar-mass black holes (BHs), in contrast to the long-held belief of a few to zero BHs. We model the population of BH low-mass X-ray binaries (BH-LMXBs), an ideal observable proxy for elusive single BHs, produced from a representative group of Milky Way GCs with variable BH populations. We simulate the formation of BH binaries in GCs through exchange interactions between binary and single stars in the company of tens to hundreds of BHs. Additionally, we consider the impact of the BH population on the rate of compact binaries undergoing gravitational wave driven mergers. The characteristics of the BH-LMXB population and binary properties are sensitive to the GCs structural parameters as well as its unobservable BH population. We find that GCs retaining ˜1000 BHs produce a galactic population of ˜150 ejected BH-LMXBs, whereas GCs retaining only ˜20 BHs produce zero ejected BH-LMXBs. Moreover, we explore the possibility that some of the presently known BH-LMXBs might have originated in GCs and identify five candidate systems.

Hunting for Stellar Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Korhonen, Heidi; Vida, Krisztián; Leitzinger, Martin; Odert, Petra; Kovács, Orsolya Eszter

2017-10-01

Coronal mass ejections (CMEs) are explosive events that occur basically daily on the Sun. It is thought that these events play a crucial role in the angular momentum and mass loss of late-type stars, and also shape the environment in which planets form and live. Stellar CMEs can be detected in optical spectra in the Balmer lines, especially in Hα, as blue-shifted extra emission/absorption. To increase the detection probability one can monitor young open clusters, in which the stars are due to their youth still rapid rotators, and thus magnetically active and likely to exhibit a large number of CMEs. Using ESO facilities and the Nordic Optical Telescope we have obtained time series of multi-object spectroscopic observations of late-type stars in six open clusters with ages ranging from 15 Myrs to 300 Myrs. Additionally, we have studied archival data of numerous active stars. These observations will allow us to obtain information on the occurrence rate of CMEs in late-type stars with different ages and spectral types. Here we report on the preliminary outcome of our studies.

Modeling Coronal Mass Ejections with EUHFORIA: A Parameter Study of the Gibson-Low Flux Rope Model using Multi-Viewpoint Observations

NASA Astrophysics Data System (ADS)

Verbeke, C.; Asvestari, E.; Scolini, C.; Pomoell, J.; Poedts, S.; Kilpua, E.

2017-12-01

Coronal Mass Ejections (CMEs) are one of the big influencers on the coronal and interplanetary dynamics. Understanding their origin and evolution from the Sun to the Earth is crucial in order to determine the impact on our Earth and society. One of the key parameters that determine the geo-effectiveness of the coronal mass ejection is its internal magnetic configuration. We present a detailed parameter study of the Gibson-Low flux rope model. We focus on changes in the input parameters and how these changes affect the characteristics of the CME at Earth. Recently, the Gibson-Low flux rope model has been implemented into the inner heliosphere model EUHFORIA, a magnetohydrodynamics forecasting model of large-scale dynamics from 0.1 AU up to 2 AU. Coronagraph observations can be used to constrain the kinematics and morphology of the flux rope. One of the key parameters, the magnetic field, is difficult to determine directly from observations. In this work, we approach the problem by conducting a parameter study in which flux ropes with varying magnetic configurations are simulated. We then use the obtained dataset to look for signatures in imaging observations and in-situ observations in order to find an empirical way of constraining the parameters related to the magnetic field of the flux rope. In particular, we focus on events observed by at least two spacecraft (STEREO + L1) in order to discuss the merits of using observations from multiple viewpoints in constraining the parameters.

Left Ventricular Function Across the Spectrum of Body Mass Index in African Americans: The Jackson Heart Study.

PubMed

Patel, Vivek G; Gupta, Deepak K; Terry, James G; Kabagambe, Edmond K; Wang, Thomas J; Correa, Aldolfo; Griswold, Michael; Taylor, Herman; Carr, John Jeffrey

2017-03-01

This study sought to assess whether body mass index (BMI) was associated with subclinical left ventricular (LV) systolic dysfunction in African-American individuals. Higher BMI is a risk factor for cardiovascular disease, including heart failure. Obesity disproportionately affects African Americans; however, the association between higher BMI and LV function in African Americans is not well understood. Peak systolic circumferential strain (ECC) was measured by tagged cardiac magnetic resonance in 1,652 adult African-American participants of the Jackson Heart Study between 2008 and 2012. We evaluated the association between BMI and ECC in multivariate linear regression and restricted cubic spline analyses adjusted for prevalent cardiovascular disease, conventional cardiovascular risk factors, LV mass, and ejection fraction. In exploratory analyses, we also examined whether inflammation, insulin resistance, or volume of visceral adipose tissue altered the association between BMI and ECC. The proportions of female, nonsmokers, diabetic, and hypertensive participants rose with increase in BMI. In multivariate-adjusted models, higher BMI was associated with worse ECC (β = 0.052; 95% confidence interval: 0.028 to 0.075), even in the setting of preserved LV ejection fraction. Higher BMI was also associated with worse ECC when accounting for markers of inflammation (C-reactive protein, E-selection, and P-selectin), insulin resistance, and volume of visceral adipose tissue. Higher BMI is significantly associated with subclinical LV dysfunction in African Americans, even in the setting of preserved LV ejection fraction. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

RUNAWAY MASSIVE STARS FROM R136: VFTS 682 IS VERY LIKELY A 'SLOW RUNAWAY'

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

Banerjee, Sambaran; Kroupa, Pavel; Oh, Seungkyung, E-mail: sambaran@astro.uni-bonn.de, E-mail: pavel@astro.uni-bonn.de, E-mail: skoh@astro.uni-bonn.de

2012-02-10

We conduct a theoretical study on the ejection of runaway massive stars from R136-the central massive, starburst cluster in the 30 Doradus complex of the Large Magellanic Cloud. Specifically, we investigate the possibility of the very massive star (VMS) VFTS 682 being a runaway member of R136. Recent observations of the above VMS, by virtue of its isolated location and its moderate peculiar motion, have raised the fundamental question of whether isolated massive star formation is indeed possible. We perform the first realistic N-body computations of fully mass-segregated R136-type star clusters in which all the massive stars are in primordialmore » binary systems. These calculations confirm that the dynamical ejection of a VMS from an R136-like cluster, with kinematic properties similar to those of VFTS 682, is common. Hence, the conjecture of isolated massive star formation is unnecessary to account for this VMS. Our results are also quite consistent with the ejection of 30 Dor 016, another suspected runaway VMS from R136. We further note that during the clusters' evolution, mergers of massive binaries produce a few single stars per cluster with masses significantly exceeding the canonical upper limit of 150 M{sub Sun }. The observations of such single super-canonical stars in R136, therefore, do not imply an initial mass function with an upper limit greatly exceeding the accepted canonical 150 M{sub Sun} limit, as has been suggested recently, and they are consistent with the canonical upper limit.« less

Volcanic plume height measured by seismic waves based on a mechanical model

USGS Publications Warehouse

Prejean, Stephanie G.; Brodsky, Emily E.

2011-01-01

In August 2008 an unmonitored, largely unstudied Aleutian volcano, Kasatochi, erupted catastrophically. Here we use seismic data to infer the height of large eruptive columns such as those of Kasatochi based on a combination of existing fluid and solid mechanical models. In so doing, we propose a connection between a common, observable, short-period seismic wave amplitude to the physics of an eruptive column. To construct a combined model, we estimate the mass ejection rate of material from the vent on the basis of the plume height, assuming that the height is controlled by thermal buoyancy for a continuous plume. Using the estimated mass ejection rate, we then derive the equivalent vertical force on the Earth through a momentum balance. Finally, we calculate the far-field surface waves resulting from the vertical force. The model performs well for recent eruptions of Kasatochi and Augustine volcanoes if v, the velocity of material exiting the vent, is 120-230 m s-1. The consistency between the seismically inferred and measured plume heights indicates that in these cases the far-field ~1 s seismic energy radiated by fluctuating flow in the volcanic jet during the eruption is a useful indicator of overall mass ejection rates. Thus, use of the model holds promise for characterizing eruptions and evaluating ash hazards to aircraft in real time on the basis of far-field short-period seismic data. This study emphasizes the need for better measurements of eruptive plume heights and a more detailed understanding of the full spectrum of seismic energy radiated coeruptively.

UV and radiofrequency observations of Wolf-Rayet stars

NASA Technical Reports Server (NTRS)

Johnson, H. M.

1971-01-01

Observations of W stars in the ultraviolet by OAO 2 and at 750 and 1400 MHz with the Green Bank telescopes are discussed. The emphasis is on the Green Bank observations of W stars with symmetric nebulae around them, their interpretation, and comparisons with other data. The implications regarding mass distribution, internal motion, flux density, ejected mass, velocity dispersion, and expanding envelopes are considered in detail.

A long-duration active region: Evolution and quadrature observations of ejective events

NASA Astrophysics Data System (ADS)

Cremades, H.; Mandrini, C. H.; Fuentes, M. C. López; Merenda, L.; Cabello, I.; López, F. M.; Poisson, M.

2017-10-01

Unknown aspects of the initiation, evolution, and associated phenomena of coronal mass ejections (CMEs), together with their capability of perturbing the fragile technological equilibrium on which nowadays society depends, turn them a compelling subject of study. While space weather forecasts are thus far not able to predict when and where in the Sun will the next CME take place, various CME triggering mechanisms have been proposed, without reaching consensus on which is the predominant one. To improve our knowledge in these respects, we investigate a long-duration active region throughout its life, from birth until decay along five solar rotations, in connection with its production of ejective events. We benefit from the wealth of solar remote-sensing data with improved temporal, spatial, and spectral resolution provided by the ground-breaking space missions STEREO, SDO, and SOHO. During the investigated time interval, which covers the months July - November 2010, the STEREO spacecraft were nearly 180 degrees apart, allowing for the uninterrupted tracking of the active region and its ensuing CMEs. The ejective aspect is examined from multi-viewpoint coronagraphic images, while the dynamics of the active region photospheric magnetic field are inspected by means of SDO/HMI data for specific subintervals of interest. The ultimate goal of this work in progress is to identify common patterns in the ejective aspect that can be connected with the active region characteristics.

Prognostic Nutritional Index and the Risk of Mortality in Patients With Acute Heart Failure.

PubMed

Cheng, Yu-Lun; Sung, Shih-Hsien; Cheng, Hao-Min; Hsu, Pai-Feng; Guo, Chao-Yu; Yu, Wen-Chung; Chen, Chen-Huan

2017-06-25

Nutritional status has been related to clinical outcomes in patients with heart failure. We assessed the association between nutritional status, indexed by prognostic nutritional index (PNI), and survival in patients hospitalized for acute heart failure. A total of 1673 patients (age 76±13 years, 68% men) hospitalized for acute heart failure in a tertiary medical center were analyzed. PNI was calculated as 10×serum albumin (g/dL)+0.005×total lymphocyte count (per mm 3 ). National Death Registry was linked to identify the clinical outcomes of all-cause and cardiovascular death. With increasing tertiles of PNI, age and N-terminal probrain natriuretic peptide decreased, and body mass index, estimated glomerular filtration rate, and hemoglobin increased. During a mean follow-up duration of 31.5 months, a higher PNI tertile was related to better survival free from all-cause and cardiovascular mortality in the total study population and in participants with either reduced or preserved left ventricular ejection fraction. After accounting for age, sex, estimated glomerular filtration rate, left ventricular ejection fraction, serum sodium level, and on-admission systolic blood pressure, PNI was independently associated with cardiovascular death and total mortality (hazard ratio per 1 SD of the natural logarithm of the PNI: 0.76 [95% CI, 0.66-0.87] and 0.79 [95% CI, 0.73-0.87], respectively). In subgroup analyses stratified by age, sex, left ventricular ejection fraction, body mass index, or estimated glomerular filtration rate, PNI was consistently related to mortality. PNI is independently associated with long-term survival in patients hospitalized for acute heart failure with either reduced or preserved left ventricular ejection fraction. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Color matters--material ejection and ion yields in UV-MALDI mass spectrometry as a function of laser wavelength and laser fluence.

PubMed

Soltwisch, Jens; Jaskolla, Thorsten W; Dreisewerd, Klaus

2013-10-01

The success of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) as a widely employed analytical tool in the biomolecular sciences builds strongly on an effective laser-material interaction that is resulting in a soft co-desorption and ionization of matrix and imbedded biomolecules. To obtain a maximized ion yield for the analyte(s) of interest, in general both wavelength and fluence need to be tuned to match the specific optical absorption profile of the used matrix. However, commonly only lasers with fixed emission wavelengths of either 337 or 355 nm are used for MALDI-MS. Here, we employed a wavelength-tunable dye laser and recorded both the neutral material ejection and the MS ion data in a wide wavelength and fluence range between 280 and 377.5 nm. α-Cyano-4-hydroxycinnamic acid (HCCA), 4-chloro-α-cyanocinnamic acid (ClCCA), α-cyano-2,4-difluorocinnamic acid (DiFCCA), and 2,5-dihydroxybenzoic acid (DHB) were investigated as matrices, and several peptides as analytes. Recording of the material ejection was achieved by adopting a photoacoustic approach. Relative ion yields were derived by division of photoacoustic and ion signals. In this way, distinct wavelength/fluence regions can be identified for which maximum ion yields were obtained. For the tested matrices, optimal results were achieved for wavelengths corresponding to areas of high optical absorption of the respective matrix and at fluences about a factor of 2-3 above the matrix- and wavelength-dependent ion detection threshold fluences. The material ejection as probed by the photoacoustic method is excellently fitted by the quasithermal model, while a sigmoidal function allows for an empirical description of the ion signal-fluence relationship.

EPISODIC EJECTION FROM ACTIVE ASTEROID 311P/PANSTARRS

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

Jewitt, David; Agarwal, Jessica; Weaver, Harold

We examine the development of the active asteroid 311P/PANSTARRS (formerly, 2013 P5) in the period from 2013 September to 2014 February using high resolution images from the Hubble Space Telescope. This multi-tailed object is characterized by a single, reddish nucleus of absolute magnitude H ≥ 18.98 ± 0.10, corresponding to an equal-area sphere of radius ≤200 ± 20 m (for assumed geometric albedo 0.29 ± 0.09). We set an upper limit to the radii of possible companion nuclei at ∼10 m. The nucleus ejected debris in nine discrete episodes, spread irregularly over a nine month interval, each time forming a distinct tail. Particles in the tailsmore » range from about 10 μm to at least 80 mm in radius, and were ejected at speeds <1 m s{sup –1}. The ratio of the total ejected dust mass to the nucleus mass is ∼3×10{sup –5}, corresponding to a global surface layer ∼2 mm thick, or to a deeper layer covering a smaller fraction of the surface. The observations are incompatible with an origin of the activity by impact or by the sublimation of entrapped ice. This object appears to be shedding its regolith by rotational (presumably YORP-driven) instability. Long-term fading of the photometry (months) is attributed to gradual dissipation of near-nucleus dust. Photometric variations on short timescales (<0.7 hr) are probably caused by fast rotation of the nucleus. However, because of limited time coverage and dilution of the nucleus signal by near-nucleus dust, we have not been able to determine the rotation period.« less

Heart Failure with Recovered EF and Heart Failure with Mid-Range EF: Current Recommendations and Controversies.

PubMed

Unkovic, Peter; Basuray, Anupam

2018-04-03

This review explores key features and potential management controversies in two emerging populations in heart failure: heart failure with recovered ejection fraction (HF-recovered EF) and heart failure with mid-range ejection fraction (HFmrEF). While HF-recovered EF patients have better outcomes than heart failure with reduced ejection fraction (HFrEF), they continue to have symptoms, persistent biomarker elevations, and abnormal outcomes suggesting a continued disease process. HFmrEF patients appear to have features of HFrEF and heart failure with preserved ejection fraction (HFpEF), but have a high prevalence of ischemic heart disease and may represent a transitory phase between the HFrEF and HFpEF. Management strategies have insufficient data to warrant standardization at this time. HF-recovered EF and HFmrEF represent new populations with unmet needs and expose the pitfalls of an EF basis for heart failure classification.

Heart Failure, Left Ventricular Remodeling, and Circulating Nitric Oxide Metabolites.

PubMed

Chirinos, Julio A; Akers, Scott R; Trieu, Lien; Ischiropoulos, Harry; Doulias, Paschalis-Thomas; Tariq, Ali; Vassim, Izzah; Koppula, Maheswara R; Syed, Amer Ahmed; Soto-Calderon, Haideliza; Townsend, Raymond R; Cappola, Thomas P; Margulies, Kenneth B; Zamani, Payman

2016-10-14

Stable plasma nitric oxide (NO) metabolites (NO M ), composed predominantly of nitrate and nitrite, are attractive biomarkers of NO bioavailability. NO M levels integrate the influence of NO-synthase-derived NO production/metabolism, dietary intake of inorganic nitrate/nitrite, and clearance of NO M . Furthermore, nitrate and nitrite, the most abundant NO M , can be reduced to NO via the nitrate-nitrite-NO pathway. We compared serum NO M among subjects without heart failure (n=126), subjects with heart failure and preserved ejection fraction (HFpEF; n=43), and subjects with heart failure and reduced ejection fraction (HFrEF; n=32). LV mass and extracellular volume fraction were measured with cardiac MRI. Plasma NO M levels were measured after reduction to NO via reaction with vanadium (III)/hydrochloric acid. Subjects with HFpEF demonstrated significantly lower unadjusted levels of NO M (8.0 μmol/L; 95% CI 6.2-10.4 μmol/L; ANOVA P=0.013) than subjects without HF (12.0 μmol/L; 95% CI 10.4-13.9 μmol/L) or those with HFrEF (13.5 μmol/L; 95% CI 9.7-18.9 μmol/L). There were no significant differences in NO M between subjects with HFrEF and subjects without HF. In a multivariable model that adjusted for age, sex, race, diabetes mellitus, body mass index, current smoking, systolic blood pressure, and glomerular filtration rate, HFpEF remained a predictor of lower NO M (β=-0.43; P=0.013). NO M did not correlate with LV mass, or LV diffuse fibrosis. HFpEF, but not HFrEF, is associated with reduced plasma NO M , suggesting greater endothelial dysfunction, enhanced clearance, or deficient dietary ingestion of inorganic nitrate. Our findings may underlie the salutary effects of inorganic nitrate supplementation demonstrated in recent clinical trials in HFpEF. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Directed energy missions for planetary defense

NASA Astrophysics Data System (ADS)

Lubin, Philip; Hughes, Gary B.; Eskenazi, Mike; Kosmo, Kelly; Johansson, Isabella E.; Griswold, Janelle; Pryor, Mark; O'Neill, Hugh; Meinhold, Peter; Suen, Jonathan; Riley, Jordan; Zhang, Qicheng; Walsh, Kevin; Melis, Carl; Kangas, Miikka; Motta, Caio; Brashears, Travis

2016-09-01

Directed energy for planetary defense is now a viable option and is superior in many ways to other proposed technologies, being able to defend the Earth against all known threats. This paper presents basic ideas behind a directed energy planetary defense system that utilizes laser ablation of an asteroid to impart a deflecting force on the target. A conceptual philosophy called DE-STAR, which stands for Directed Energy System for Targeting of Asteroids and exploration, is an orbiting stand-off system, which has been described in other papers. This paper describes a smaller, stand-on system known as DE-STARLITE as a reduced-scale version of DE-STAR. Both share the same basic heritage of a directed energy array that heats the surface of the target to the point of high surface vapor pressure that causes significant mass ejection thus forming an ejection plume of material from the target that acts as a rocket to deflect the object. This is generally classified as laser ablation. DE-STARLITE uses conventional propellant for launch to LEO and then ion engines to propel the spacecraft from LEO to the near-Earth asteroid (NEA). During laser ablation, the asteroid itself provides the propellant source material; thus a very modest spacecraft can deflect an asteroid much larger than would be possible with a system of similar mission mass using ion beam deflection (IBD) or a gravity tractor. DE-STARLITE is capable of deflecting an Apophis-class (325 m diameter) asteroid with a 1- to 15-year targeting time (laser on time) depending on the system design. The mission fits within the rough mission parameters of the Asteroid Redirect Mission (ARM) program in terms of mass and size. DE-STARLITE also has much greater capability for planetary defense than current proposals and is readily scalable to match the threat. It can deflect all known threats with sufficient warning.

Hst Measurements Of Main Belt Comet 300163

NASA Astrophysics Data System (ADS)

Jewitt, David; Weaver, H.; Agarwal, J.; Mutchler, M.; Larson, S.

2012-10-01

Asteroid 300163 (semimajor axis 3.05 AU, eccentricity 0.20, inclination 3 deg., Tisserand parameter 3.20) is a source of dust, giving it the dual cometary designation P/2006 VW139. It satisfies the definition of a main-belt comet (MBC) by having the orbital character of a main-belt asteroid but the diffuse appearance of a comet. We obtained Hubble Space Telescope observations of this object in December 2011 in order to study the morphology of the ejected dust at the highest angular resolution and to determine the cause of the mass loss from the nucleus. One of the two HST observing epochs was carefully timed to coincide with the Earth's crossing of the orbital plane (out of plane angle 0.01 deg.) to obtain a measure of the vertical velocity dispersion free from the effects of projection. We find an extraordinarily thin dust sheet and infer a sub-meter per second dust ejection velocity. Observations at the second epoch show a change in the near-nucleus dust morphology that indicates continuing ejection (i.e. the dust emission is not impulsive). We use the low velocity ejection, coupled with the absence of an observable coma, to help constrain the possible source mechanisms for the dust.

Efficient common-envelope ejection through dust-driven winds

NASA Astrophysics Data System (ADS)

Glanz, Hila; Perets, Hagai B.

2018-04-01

Common-envelope evolution (CEE) is the short-lived phase in the life of an interacting binary-system during which two stars orbit inside a single shared envelope. Such evolution is thought to lead to the inspiral of the binary, the ejection of the extended envelope and the formation of a remnant short-period binary. However, detailed hydrodynamical models of CEE encounter major difficulties. They show that following the inspiral most of the envelope is not ejected; though it expands to larger separations, it remains bound to the binary. Here we propose that dust-driven winds can be produced following the CEE. These can evaporate the envelope following similar processes operating in the ejection of the envelopes of AGB stars. Pulsations in an AGB-star drives the expansion of its envelope, allowing the material to cool down to low temperatures thus enabling dust condensation. Radiation pressure on the dust accelerates it, and through its coupling to the gas it drives winds which eventually completely erode the envelope. We show that the inspiral phase in CE-binaries can effectively replace the role of stellar pulsation and drive the CE expansion to scales comparable with those of AGB stars, and give rise to efficient mass-loss through dust-driven winds.

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

Laskin, Julia

In this work, resonant ejection coupled with surface-induced dissociation (SID) in a Fourier transform ion cyclotron resonance mass spectrometer is used to examine fragmentation kinetics of two singly protonated hexapeptides, RYGGFL and KYGGFL, containing the basic arginine residue and less basic lysine residue at the N-terminus. The kinetics of individual reaction channels at different collision energies are probed by applying a short ejection pulse (1 ms) in resonance with the cyclotron frequency of a selected fragment ion and varying the delay time between ion-surface collision and resonant ejection while keeping total reaction delay time constant. Rice-Ramsperger-Kassel-Marcus (RRKM) modeling of themore » experimental data provides accurate threshold energies and activation entropies of individual reaction channels. Substitution of arginine with less basic lysine has a pronounced effect on the observed fragmentation kinetics of several pathways, including the b2 ion formation, but has little or no effect on formation of the b5+H2O fragment ion. The combination of resonant ejection SID, time- and collision energy-resolved SID, and RRKM modeling of both types of experimental data provides a detailed mechanistic understanding of the primary dissociation pathways of complex gaseous ions.« less

New Approach for Studying Slow Fragmentation Kinetics in FT-ICR: Surface-Induced Dissociation Combined with Resonant Ejection

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

Laskin, Julia; Futrell, Jean H.

2015-02-01

We introduce a new approach for studying the kinetics of large ion fragmentation in the gas phase by coupling surface-induced dissociation (SID) in a Fourier transform ion cyclotron resonance mass spectrometer with resonant ejection of selected fragment ions using a relatively short (5 ms) ejection pulse. The approach is demonstrated for singly protonated angiotensin III ions excited by collisions with a self-assembled monolayer of alkylthiol on gold (HSAM). The overall decomposition rate and rate constants of individual reaction channels are controlled by varying the kinetic energy of the precursor ion in a range of 65–95 eV. The kinetics of peptidemore » fragmentation are probed by varying the delay time between resonant ejection and fragment ion detection at a constant total reaction time. RRKM modeling indicates that the shape of the kinetics plots is strongly affected by the shape and position of the energy deposition function (EDF) describing the internal energy distribution of the ion following ion-surface collision. Modeling of the kinetics data provides detailed information on the shape of the EDF and energy and entropy effects of individual reaction channels.« less

Atmosphere Impact Losses

NASA Astrophysics Data System (ADS)

Schlichting, Hilke E.; Mukhopadhyay, Sujoy

2018-02-01

Determining the origin of volatiles on terrestrial planets and quantifying atmospheric loss during planet formation is crucial for understanding the history and evolution of planetary atmospheres. Using geochemical observations of noble gases and major volatiles we determine what the present day inventory of volatiles tells us about the sources, the accretion process and the early differentiation of the Earth. We further quantify the key volatile loss mechanisms and the atmospheric loss history during Earth's formation. Volatiles were accreted throughout the Earth's formation, but Earth's early accretion history was volatile poor. Although nebular Ne and possible H in the deep mantle might be a fingerprint of this early accretion, most of the mantle does not remember this signature implying that volatile loss occurred during accretion. Present day geochemistry of volatiles shows no evidence of hydrodynamic escape as the isotopic compositions of most volatiles are chondritic. This suggests that atmospheric loss generated by impacts played a major role during Earth's formation. While many of the volatiles have chondritic isotopic ratios, their relative abundances are certainly not chondritic again suggesting volatile loss tied to impacts. Geochemical evidence of atmospheric loss comes from the {}3He/{}^{22}Ne, halogen ratios (e.g., F/Cl) and low H/N ratios. In addition, the geochemical ratios indicate that most of the water could have been delivered prior to the Moon forming impact and that the Moon forming impact did not drive off the ocean. Given the importance of impacts in determining the volatile budget of the Earth we examine the contributions to atmospheric loss from both small and large impacts. We find that atmospheric mass loss due to impacts can be characterized into three different regimes: 1) Giant Impacts, that create a strong shock transversing the whole planet and that can lead to atmospheric loss globally. 2) Large enough impactors (m_{cap} ≳ √{2} ρ0 (π h R)^{3/2}, r_{cap}˜25 km for the current Earth), that are able to eject all the atmosphere above the tangent plane of the impact site, where h, R and ρ0 are the atmospheric scale height, radius of the target, and its atmospheric density at the ground. 3) Small impactors (m_{min}>4 πρ0 h3, r_{min}˜ 1 km for the current Earth), that are only able to eject a fraction of the atmospheric mass above the tangent plane. We demonstrate that per unit impactor mass, small impactors with r_{min} < r < r_{cap} are the most efficient impactors in eroding the atmosphere. In fact for the current atmospheric mass of the Earth, they are more than five orders of magnitude more efficient (per unit impactor mass) than giant impacts, implying that atmospheric mass loss must have been common. The enormous atmospheric mass loss efficiency of small impactors is due to the fact that most of their impact energy and momentum is directly available for local mass loss, where as in the giant impact regime a lot of energy and momentum is 'wasted' by having to create a strong shock that can transverse the entirety of the planet such that global atmospheric loss can be achieved. In the absence of any volatile delivery and outgassing, we show that the population of late impactors inferred from the lunar cratering record containing 0.1% M_{\\oplus } is able to erode the entire current Earth's atmosphere implying that an interplay of erosion, outgassing and volatile delivery is likely responsible for determining the atmospheric mass and composition of the early Earth. Combining geochemical observations with impact models suggest an interesting synergy between small and big impacts, where giant impacts create large magma oceans and small and larger impacts drive the atmospheric loss.

Evolution of echocardiography in subclinical detection of cancer therapy-related cardiac dysfunction.

PubMed

Moudgil, Rohit; Hassan, Saamir; Palaskas, Nicolas; Lopez-Mattei, Juan; Banchs, Jose; Yusuf, Syed Wamique

2018-05-11

Cancer therapies have resulted in increased survivorship in oncological patients. However, the benefits have been marred by the development of premature cardiovascular disease. The current definition outlines measurement of ejection fraction as a mean to diagnose cancer therapeutic-related cardiac dysfunction (CTRCD); however, up to 58% of the patients do not regain their cardiac function after the CTRCD diagnosis, despite therapeutic interventions. Therefore, there has been a growing interest in the markers for early myocardial changes (ie, changes with normal left ventricular ejection fraction [LVEF]) that may predict the development of subsequent left ventricular ejection fraction reduction or progression to heart failure. This review will highlight the use of diastolic parameters, tissue Doppler imaging (TDI), and speckle tracking echocardiogram (STE) as emerging technologies which can potentially detect cardiac dysfunction thereby stratifying patients for cardioprotective therapies. The goal of this manuscript was to highlight the concepts and discuss the current controversies surrounding these echocardiographic imaging modalities. © 2018 Wiley Periodicals, Inc.

Global Energetics in Solar Flares and Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Aschwanden, Markus J.

2017-08-01

We present a statistical study of the energetics of coronal mass ejections (CME) and compare it with the magnetic, thermal, and nonthermal energy dissipated in flares. The physical parameters of CME speeds, mass, and kinetic energies are determined with two different independent methods, i.e., the traditional white-light scattering method using LASCO/SOHO data, and the EUV dimming method using AIA/SDO data. We analyze all 860 GOES M- and X-class flare events observed during the first 7 years (2010-2016) of the SDO mission. The new ingredients of our CME modeling includes: (1) CME geometry in terms of a self-similar adiabatic expansion, (2) DEM analysis of CME mass over entire coronal temperature range, (3) deceleration of CME due to gravity force which controls the kinetic and potentail CME energy as a function of time, (4) the critical speed that controls eruptive and confined CMEs, (5) the relationship between the center-of-mass motion during EUV dimming and the leading edge motion observed in white-light coronagraphs. Novel results are: (1) Physical parameters obtained from both the EUV dimming and white-light method can be reconciled; (2) the equi-partition of CME kinetic and thermal flare energy; (3) the Rosner-Tucker-Vaiana scaling law. We find that the two methods in EUV and white-light wavelengths are highly complementary and yield more complete models than each method alone.

Chronology, morphology and stratigraphy of pumiceous pyroclastic-flow (ignimbrite) deposits from the eruption of Mount St. Helens on 18 May 1983

NASA Technical Reports Server (NTRS)

Criswell, C. W.; Elston, W. E.

1984-01-01

Between 1217 and 1620 hours (PDT), on May 18, 1980, the magmatic eruption column of Mount St. Helens formed an ash fountain and pyroclastic flows dominated the eruption process over tephra ejection. Eurption-rate pulsations generally increased to a maximum at 1600 to 1700 hrs. After 1620 hrs, the eruption assumed an open-vent discharge with strong, vertical ejection of tephra. Relative eruption rates (relative mass flux rates) of the pyroclastic flows were determined by correlating sequential photographs and SLAR images, obtained during the eruption, with stratigraphy and surface morphology of the deposits.

Jupiter - Solid or Gaseous? Ask Juno

NASA Astrophysics Data System (ADS)

Ackerman, J. A., Jr.

2015-12-01

Data from Cassini, Galileo, S-L 9 and Ulysses suggest Jupiter and Saturn are solid, frozen, Methane Gas Hydrate (MGH) planets. The bulk of these giants formed slow and cold by the natural accretion of snowflakes at their current orbital radii in the presence of methane, forming rigid incompressible bodies. MGH, (CH4)8(H2O)46 (d=0.9), is consistent with the abundances of the elements comprising the Earth (H>O>C). Their combined MGH comprises >250 earth-masses of H2O. Jupiter (d=1.33) incorporated most of the heavy elements in the nascent solar system, exemplified by an enormously enhanced D/H. The temperature excess of Jupiter's atmosphere is the result of an impact ~6,000 years BP, triggering an incredibly energetic fusion explosion which ejected the masses of the proto-Galilean moons. It also initiated a continuing fusion furnace in the crater producing a jet of hot gases extending >2x106 km, beyond Callisto. The jet has slowly diminished over 6,000 years, resulting in the differences in the four Galilean Moons. The mass ejection (ang. mom.) slowed Jupiter's rotation until ~1930, currently interpreted as a drift of the Great Red Spot. A diminishing fusion reaction (D + p → 3He + γ) continues to this day, producing Jupiter's atmospheric 'temperature excess'. Jupiter's rapid rotation deflects the rising vortex of hot gases from the fusion reaction horizontally, driving multiple zonal vortices, constrained by the frozen MGH surface <1000 km below the cloud tops. It appears as the tilted Great Red Spot (GRS), ~30,000 km to the west of the crater at 22 o S Lat., which has remained unchanged in the last 350 years - impossible due to the enormous Coliolis effect. Streams of 3He produced in the fusion reaction exiting Jupiter through the center of the GRS have been detected by the Galileo probe and orbiter, Ulysses, and Cassini. The fusion releases methane, also heavy elements which oxidize as they rise, producing the cloud-top colors. The MGH hypothesis explains the >6 minute delays of the larger S-L 9 'main events' as the time required for the mushroom clouds from their impacts to reach the cloud tops. The Juno MWR can potentially detect the fusion source and certainly the hot, longitudinally extended column forming the GRS. The Gravity Experiment should detect the basin in which it is located, possibly others.

The Death Spiral of T Pyxidis

NASA Astrophysics Data System (ADS)

Patterson, J.; Oksanen, A.; Monard, B.; Rea, R.; Hambsch, F.; McCormick, J.; Nelson, P.; Kemp, J.; Allen, W.; Krajci, T.; Lowther, S.; Dvorak, S.; Richards, T.; Myers, G.; Bolt, G.

2014-12-01

We report a long campaign to track the 1.8 hr photometric wave in the recurrent nova T Pyxidis, using the global telescope network of the Center for Backyard Astrophysics. During 1996-2011, that wave was highly stable in amplitude and waveform, resembling the orbital wave commonly seen in supersoft binaries. The period, however, was found to increase on a timescale P/P =3 ×105 yr. This suggests a mass transfer rate of ˜ 10-7 M⊙/yr in quiescence. The orbital signal became vanishingly weak (< 0.003 mag) near maximum light of the 2011 eruption. After it returned to visibility near V=11, the orbital period had increased by 0.0054(6) %. This is a measure of the mass ejected in the nova outburst. For a plausible choice of binary parameters, that mass is at least 3×10-5 M⊙, and probably more. This represents > 300 yr of accretion at the pre-outburst rate, but the time between outbursts was only 45 yr. Thus the erupting white dwarf seems to have ejected at least 6 × more mass than it accreted. If this eruption is typical, the white dwarf must be eroding, rather than growing, in mass — dashing the star's hopes of ever becoming famous via a supernova explosion. Instead, it seems likely that the binary dynamics are basically a suicide pact between the eroding white dwarf and the low-mass secondary, excited and rapidly whittled down, probably by the white dwarf's EUV radiation.

Common Envelope Shaping of Planetary Nebulae

NASA Astrophysics Data System (ADS)

García-Segura, Guillermo; Ricker, Paul M.; Taam, Ronald E.

2018-06-01

The morphology of planetary nebulae emerging from the common envelope phase of binary star evolution is investigated. Using initial conditions based on the numerical results of hydrodynamical simulations of the common envelope phase, it was found that the shapes and sizes of the resulting nebula are very sensitive to the effective temperature of the remnant core, the mass-loss rate at the onset of the common envelope phase, and the mass ratio of the binary system. These parameters are related to the efficiency of the mass ejection after the spiral-in phase, the stellar evolutionary phase (i.e., RG, AGB, or TP-AGB), and the degree of departure from spherical symmetry in the stellar wind mass-loss process itself, respectively. It was also found that the shapes are mostly bipolar in the early phase of evolution, but that they can quickly transition to elliptical and barrel-type shapes. Solutions for nested lobes are found where the outer lobes are usually bipolar and the inner lobes are elliptical, bipolar, or barrel-type, a result due to the flow of the photo-evaporated gas from the equatorial region. Also, the lobes can be produced without the need for two distinct mass ejection events. In all the computations, the bulk of the mass is concentrated in the orbital or equatorial plane, in the form of a large toroid, which can be either neutral (early phases) or photoionized (late phases), depending of the evolutionary state of the system.

Two stellar-mass black holes in the globular cluster M22.

PubMed

Strader, Jay; Chomiuk, Laura; Maccarone, Thomas J; Miller-Jones, James C A; Seth, Anil C

2012-10-04

Hundreds of stellar-mass black holes probably form in a typical globular star cluster, with all but one predicted to be ejected through dynamical interactions. Some observational support for this idea is provided by the lack of X-ray-emitting binary stars comprising one black hole and one other star ('black-hole/X-ray binaries') in Milky Way globular clusters, even though many neutron-star/X-ray binaries are known. Although a few black holes have been seen in globular clusters around other galaxies, the masses of these cannot be determined, and some may be intermediate-mass black holes that form through exotic mechanisms. Here we report the presence of two flat-spectrum radio sources in the Milky Way globular cluster M22, and we argue that these objects are black holes of stellar mass (each ∼10-20 times more massive than the Sun) that are accreting matter. We find a high ratio of radio-to-X-ray flux for these black holes, consistent with the larger predicted masses of black holes in globular clusters compared to those outside. The identification of two black holes in one cluster shows that ejection of black holes is not as efficient as predicted by most models, and we argue that M22 may contain a total population of ∼5-100 black holes. The large core radius of M22 could arise from heating produced by the black holes.

Characteristics and Geoeffectiveness of Small-scale Magnetic Flux Ropes in the Solar Wind

NASA Astrophysics Data System (ADS)

Kim, Myeong Joon; Park, Kyung Sun; Lee, Dae-Young; Choi, Cheong-Rim; Kim, Rok Soon; Cho, Kyungsuk; Choi, Kyu-Cheol; Kim, Jaehun

2017-12-01

Magnetic flux ropes, often observed during intervals of interplanetary coronal mass ejections, have long been recognized to be critical in space weather. In this work, we focus on magnetic flux rope structure but on a much smaller scale, and not necessarily related to interplanetary coronal mass ejections. Using near-Earth solar wind advanced composition explorer (ACE) observations from 1998 to 2016, we identified a total of 309 small-scale magnetic flux ropes (SMFRs). We compared the characteristics of identified SMFR events with those of normal magnetic cloud (MC) events available from the existing literature. First, most of the MCs and SMFRs have similar values of accompanying solar wind speed and proton densities. However, the average magnetic field intensity of SMFRs is weaker ( 7.4 nT) than that of MCs ( 10.6 nT). Also, the average duration time and expansion speed of SMFRs are 2.5 hr and 2.6 km/s, respectively, both of which are smaller by a factor of 10 than those of MCs. In addition, we examined the geoeffectiveness of SMFR events by checking their correlation with magnetic storms and substorms. Based on the criteria Sym-H < -50 nT (for identification of storm occurrence) and AL < -200 nT (for identification of substorm occurrence), we found that for 88 SMFR events (corresponding to 28.5 % of the total SMFR events), substorms occurred after the impact of SMFRs, implying a possible triggering of substorms by SMFRs. In contrast, we found only two SMFRs that triggered storms. We emphasize that, based on a much larger database than used in previous studies, all these previously known features are now firmly confirmed by the current work. Accordingly, the results emphasize the significance of SMFRs from the viewpoint of possible triggering of substorms.

Size, shape, and stamina: the impact of left ventricular geometry on exercise capacity.

PubMed

Lam, Carolyn S P; Grewal, Jasmine; Borlaug, Barry A; Ommen, Steve R; Kane, Garvan C; McCully, Robert B; Pellikka, Patricia A

2010-05-01

Although several studies have examined the cardiac functional determinants of exercise capacity, few have investigated the effects of structural remodeling. The current study evaluated the association between cardiac geometry and exercise capacity. Subjects with ejection fraction > or = 50% and no valvular disease, myocardial ischemia, or arrhythmias were identified from a large prospective exercise echocardiography database. Left ventricular mass index and relative wall thickness were used to classify geometry into normal, concentric remodeling, eccentric hypertrophy, and concentric hypertrophy. All of the subjects underwent symptom-limited treadmill exercise according to standard Bruce protocol. Maximal exercise tolerance was measured in metabolic equivalents. Of 366 (60+/-14 years; 57% male) subjects, 166 (45%) had normal geometry, 106 (29%) had concentric remodeling, 40 (11%) had eccentric hypertrophy, and 54 (15%) had concentric hypertrophy. Geometry was related to exercise capacity: in descending order, the maximum achieved metabolic equivalents were 9.9+/-2.8 in normal, 8.9+/-2.6 in concentric remodeling, 8.6+/-3.1 in eccentric hypertrophy, and 8.0+/-2.7 in concentric hypertrophy (all P<0.02 versus normal). Left ventricular mass index and relative wall thickness were negatively correlated with exercise tolerance in metabolic equivalents (r=-0.14; P=0.009 and r=-0.21; P<0.001, respectively). Augmentation of heart rate and ejection fraction with exercise were blunted in concentric hypertrophy compared with normal, even after adjusting for medications. In conclusion, the pattern of ventricular remodeling is related to exercise capacity among low-risk adults. Subjects with concentric hypertrophy display the greatest limitation, and this is related to reduced systolic and chronotropic reserve. Reverse remodeling strategies may prevent or treat functional decline in patients with structural heart disease.

Size, Shape and Stamina: The Impact of Left Ventricular Geometry on Exercise Capacity

PubMed Central

Lam, Carolyn S.P.; Grewal, Jasmine; Borlaug, Barry A.; Ommen, Steve R.; Kane, Garvan C.; McCully, Robert B.; Pellikka, Patricia A.

2010-01-01

While several studies have examined the cardiac functional determinants of exercise capacity, few have investigated the effects of structural remodeling. The current study evaluated the association between cardiac geometry and exercise capacity. Subjects with ejection fraction ≥ 50% and no valvular disease, myocardial ischemia or arrhythmias were identified from a large prospective exercise echocardiography database. Left ventricular mass index and relative wall thickness were used to classify geometry into normal, concentric remodeling, eccentric hypertrophy and concentric hypertrophy. All subjects underwent symptom-limited treadmill exercise according to standard Bruce protocol. Maximal exercise tolerance was measured in metabolic equivalents. Of 366 (60±14 years; 57% male) subjects, 166(45%) had normal geometry, 106(29%) had concentric remodeling, 40(11%) had eccentric hypertrophy and 54(15%) had concentric hypertrophy. Geometry was related to exercise capacity: in descending order, the maximum achieved metabolic equivalents was 9.9±2.8 in normal, 8.9±2.6 in concentric remodeling, 8.6±3.1 in eccentric hypertrophy and 8.0±2.7 in concentric hypertrophy (all p<0.02 vs normal). Left ventricular mass index and relative wall thickness were negatively correlated with exercise tolerance in metabolic equivalents (r= -0.14; p=0.009 and r= -0.21; p<0.001, respectively). Augmentation of heart rate and ejection fraction with exercise were blunted in concentric hypertrophy compared to normal, even after adjusting for medications. In conclusion, the pattern of ventricular remodeling is related to exercise capacity among low-risk adults. Subjects with concentric hypertrophy display the greatest limitation and this is related to reduced systolic and chronotropic reserve. Reverse remodeling strategies may prevent or treat functional decline in patients with structural heart disease. PMID:20215563

Validation of the CME Geomagnetic Forecast Alerts Under the COMESEP Alert System

NASA Astrophysics Data System (ADS)

Dumbović, Mateja; Srivastava, Nandita; Rao, Yamini K.; Vršnak, Bojan; Devos, Andy; Rodriguez, Luciano

2017-08-01

Under the European Union 7th Framework Programme (EU FP7) project Coronal Mass Ejections and Solar Energetic Particles (COMESEP, http://comesep.aeronomy.be), an automated space weather alert system has been developed to forecast solar energetic particles (SEP) and coronal mass ejection (CME) risk levels at Earth. The COMESEP alert system uses the automated detection tool called Computer Aided CME Tracking (CACTus) to detect potentially threatening CMEs, a drag-based model (DBM) to predict their arrival, and a CME geoeffectiveness tool (CGFT) to predict their geomagnetic impact. Whenever CACTus detects a halo or partial halo CME and issues an alert, the DBM calculates its arrival time at Earth and the CGFT calculates its geomagnetic risk level. The geomagnetic risk level is calculated based on an estimation of the CME arrival probability and its likely geoeffectiveness, as well as an estimate of the geomagnetic storm duration. We present the evaluation of the CME risk level forecast with the COMESEP alert system based on a study of geoeffective CMEs observed during 2014. The validation of the forecast tool is made by comparing the forecasts with observations. In addition, we test the success rate of the automatic forecasts (without human intervention) against the forecasts with human intervention using advanced versions of the DBM and CGFT (independent tools available at the Hvar Observatory website, http://oh.geof.unizg.hr). The results indicate that the success rate of the forecast in its current form is unacceptably low for a realistic operation system. Human intervention improves the forecast, but the false-alarm rate remains unacceptably high. We discuss these results and their implications for possible improvement of the COMESEP alert system.

Our Dynamic Sun (Hannes Alfvén Medal Lecture)

NASA Astrophysics Data System (ADS)

Priest, Eric

2017-04-01

The Sun, an object of worship for early civilisations, is the main source of light and life on Earth and of our space weather, with many subtle effects on our environment. The lecture will introduce you to the Sun and its dynamic phenomena, and will aim to show how our understanding of many aspects of the Sun has been revolutionized over the past few years by current spacecraft observations and models. Much of the dynamic behaviour is driven by the magnetic field since, in the outer atmosphere (or corona), it represents by far the largest source of energy. The interior of the Sun, revealed by solar seismology, possesses a strong shear layer at the base of the convection zone, where sunspot magnetic fields are generated. But a small-scale dynamo is also operating near the surface of the Sun, generating magnetic fields that thread the lowest layer of the solar atmosphere, the photosphere, in a turbulent convective state. Above the photosphere lies the highly dynamic fine-scale chromosphere and beyond that the rare corona at high temperatures exceeding one million degrees K. Magnetic mechanisms for heating the corona (an intriguing puzzle) will be described. Other puzzles include the structure of giant flux ropes, known as prominences, which have complex fine structure. Occasionally, they erupt and produce huge ejections of mass and magnetic field (coronal mass ejections), which can disrupt the space environment of the Earth. When such eruptions originate in active regions around sunspots, they are also associated with solar flares, where magnetic energy is converted to kinetic, heat and fast particle energy. A new theory will be presented for the origin of the twist that is observed in erupting prominences.

Near-Sun and 1 AU magnetic field of coronal mass ejections: a parametric study

NASA Astrophysics Data System (ADS)

Patsourakos, S.; Georgoulis, M. K.

2016-11-01

Aims: The magnetic field of coronal mass ejections (CMEs) determines their structure, evolution, and energetics, as well as their geoeffectiveness. However, we currently lack routine diagnostics of the near-Sun CME magnetic field, which is crucial for determining the subsequent evolution of CMEs. Methods: We recently presented a method to infer the near-Sun magnetic field magnitude of CMEs and then extrapolate it to 1 AU. This method uses relatively easy to deduce observational estimates of the magnetic helicity in CME-source regions along with geometrical CME fits enabled by coronagraph observations. We hereby perform a parametric study of this method aiming to assess its robustness. We use statistics of active region (AR) helicities and CME geometrical parameters to determine a matrix of plausible near-Sun CME magnetic field magnitudes. In addition, we extrapolate this matrix to 1 AU and determine the anticipated range of CME magnetic fields at 1 AU representing the radial falloff of the magnetic field in the CME out to interplanetary (IP) space by a power law with index αB. Results: The resulting distribution of the near-Sun (at 10 R⊙) CME magnetic fields varies in the range [0.004, 0.02] G, comparable to, or higher than, a few existing observational inferences of the magnetic field in the quiescent corona at the same distance. We also find that a theoretically and observationally motivated range exists around αB = -1.6 ± 0.2, thereby leading to a ballpark agreement between our estimates and observationally inferred field magnitudes of magnetic clouds (MCs) at L1. Conclusions: In a statistical sense, our method provides results that are consistent with observations.

Real-Time Three-Dimensional Echocardiography: Characterization of Cardiac Anatomy and Function-Current Clinical Applications and Literature Review Update.

PubMed

Velasco, Omar; Beckett, Morgan Q; James, Aaron W; Loehr, Megan N; Lewis, Taylor G; Hassan, Tahmin; Janardhanan, Rajesh

2017-01-01

Our review of real-time three-dimensional echocardiography (RT3DE) discusses the diagnostic utility of RT3DE and provides a comparison with two-dimensional echocardiography (2DE) in clinical cardiology. A Pubmed literature search on RT3DE was performed using the following key words: transthoracic, two-dimensional, three-dimensional, real-time, and left ventricular (LV) function. Articles included perspective clinical studies and meta-analyses in the English language, and focused on the role of RT3DE in human subjects. Application of RT3DE includes analysis of the pericardium, right ventricular (RV) and LV cavities, wall motion, valvular disease, great vessels, congenital anomalies, and traumatic injury, such as myocardial contusion. RT3DE, through a transthoracic echocardiography (TTE), allows for increasingly accurate volume and valve motion assessment, estimated LV ejection fraction, and volume measurements. Chamber motion and LV mass approximation have been more accurately evaluated by RT3DE by improved inclusion of the third dimension and quantification of volumetric movement. Moreover, RT3DE was shown to have no statistical significance when comparing the ejection fractions of RT3DE to cardiac magnetic resonance (CMR). Analysis of RT3DE data sets of the LV endocardial exterior allows for the volume to be directly quantified for specific phases of the cardiac cycle, ranging from end systole to end diastole, eliminating error from wall motion abnormalities and asymmetrical left ventricles. RT3DE through TTE measures cardiac function with superior diagnostic accuracy in predicting LV mass, systolic function, along with LV and RV volume when compared with 2DE with comparable results to CMR.

Low coronal signatures of coronal mass ejections

NASA Astrophysics Data System (ADS)

Attrill, Gemma Diana Ruth

Coronal mass ejections (CMEs) are vast eruptions of magnetised plasma that explode from the solar atmosphere. This thesis focuses on understanding the nascent stages of CMEs, and their magnetic development as they expand into the interplanetary space of our solar system. This is an important part of our effort to understand the space weather environment that we live in, and increasingly interact with through satellite communications technologies. Predominantly through combining extreme ultra-violet imaging and magnetogram data, two low coronal signatures of CMEs, namely coronal waves and dimmings, are studied. A comprehensive list of observational properties of EIT coronal waves is compiled and potential counterparts in radio, Ha, soft X-rays and He n wavelengths are also discussed. New observational constraints on EIT coronal waves are presented, most notably diffuse coronal waves are shown to have a magnetic nature. Finding that many observational constraints are not satisfactorily explained by current theories, a new model for understanding the physical nature of diffuse coronal waves is developed. The new model interprets diffuse coronal "wave" bright fronts to be the low coronal magnetic footprint of CMEs. Implications for developing our understanding of how CMEs become large-scale in the low corona are discussed. Application of the model demonstrates how an understanding of the formation of complex global-scale coronal dimmings can be derived. For the first time it is shown that study of the evolution and magnetic nature of coronal dimming regions can be used to probe the post-eruptive evolution of the CME. Finally, a study is presented regarding why and how CME-related dimmings recover, despite the "open" magnetic connectivity of the ejecta to the Sun being maintained as indicated by electron heat flux measurements at 1 AU.

Activity of the 1998 Leonid Shower From the Video Records

NASA Technical Reports Server (NTRS)

Jenniskens, Peter

1999-01-01

Video observations of the Leonid shower aboard two aircraft in the 1998 Leonid multi-instrument aircraft campaign and from ground locations in China are presented. Observing at altitude proved particularly effective, with four times higher rates due to low extinction and low angular velocity at the horizon. The rates, derived from a total of 2500 Leonid meteors, trace at least two distinct dust components. One dominated the night of 1998 November 16/17. This two-day wide component was rich in bright meteors with r = N (m + 1)/N (m) approximately equal 1.5 (s = 1.4) and peaked at an influx of 3.1 +/- 0.4 x 10(exp -12) /sq m.s (for particles of mass < 7 x 10(exp -5) g) at solar longitude lambda(sub 0) approximately equal 234.52 (Eq. J2000). The other more narrow component peaked on 1998 November 17/18 at lambda(sub 0) = 235.31 +/- 0.01. Rates were elevated above the broad component between lambda(sub 0) = 235.15 and 235.40, symmetric around the current node of the parent comet 55P/Tempel-Tuttle, peaking at 5.1 +/- 0.2 x 10(exp -12) /sq m.s. The population index was higher, r = 1.8 +/- 0.1 (s = 1.7), but not as high as in past Leonid storms (r = 3.0). The flux profile of this component has an unusual asymmetric shape, which implies a blend of contributions from at least two different but relatively recent epochs of ejection. The variation of r across the profile might be due to mass-dependent ejection velocities of the narrowest component. High rates of faint meteors occurred only in an isolated five-minute interval at lambda(sub 0) = 235.198, which is likely the result of a single meteoroid breakup in space.

The cosmic baryon cycle and galaxy mass assembly in the FIRE simulations

NASA Astrophysics Data System (ADS)

Anglés-Alcázar, Daniel; Faucher-Giguère, Claude-André; Kereš, Dušan; Hopkins, Philip F.; Quataert, Eliot; Murray, Norman

2017-10-01

We use cosmological simulations from the FIRE (Feedback In Realistic Environments) project to study the baryon cycle and galaxy mass assembly for central galaxies in the halo mass range Mhalo ˜ 1010-1013 M⊙. By tracing cosmic inflows, galactic outflows, gas recycling and merger histories, we quantify the contribution of physically distinct sources of material to galaxy growth. We show that in situ star formation fuelled by fresh accretion dominates the early growth of galaxies of all masses, while the re-accretion of gas previously ejected in galactic winds often dominates the gas supply for a large portion of every galaxy's evolution. Externally processed material contributes increasingly to the growth of central galaxies at lower redshifts. This includes stars formed ex situ and gas delivered by mergers, as well as smooth intergalactic transfer of gas from other galaxies, an important but previously underappreciated growth mode. By z = 0, wind transfer, I.e. the exchange of gas between galaxies via winds, can dominate gas accretion on to ˜L* galaxies over fresh accretion and standard wind recycling. Galaxies of all masses re-accrete ≳50 per cent of the gas ejected in winds and recurrent recycling is common. The total mass deposited in the intergalactic medium per unit stellar mass formed increases in lower mass galaxies. Re-accretion of wind ejecta occurs over a broad range of time-scales, with median recycling times (˜100-350 Myr) shorter than previously found. Wind recycling typically occurs at the scale radius of the halo, independent of halo mass and redshift, suggesting a characteristic recycling zone around galaxies that scales with the size of the inner halo and the galaxy's stellar component.

Definition Study of a Coordinated Group of Experiments to Measure and Monitor the in situ Plasma and Electromagnetic Environment of a Polar Orbiting Space Shuttle.

DTIC Science & Technology

1985-09-01

instruments should be included in the SACS package: Mass Spectrometer - The ion/neutral quadrupole mass spectrometer obtains composition measurements of...contamination. The preferred direction is into the RAM. The field-of-view is _ 200 and t ie mass range is 1 to 64 AMU.- Energetic Particle Deteotors...Dimensions Dimensions Weight Item Stowed (cm) Deployed (cm) (kg) Ejected Recovery Mass Spectrometer N/A 15x7x7 bxbx6 12.7 N/A N/A Energetic Particle Det N

SOHO Observations of a Coronal Mass Ejection

NASA Astrophysics Data System (ADS)

Akmal, Arya; Raymond, John C.; Vourlidas, Angelos; Thompson, Barbara; Ciaravella, A.; Ko, Y.-K.; Uzzo, M.; Wu, R.

2001-06-01

We describe a coronal mass ejection (CME) observed on 1999 April 23 by the Ultraviolet Coronagraph Spectrometer (UVCS), the Extreme-Ultraviolet Imaging Telescope (EIT), and the Large-Angle and Spectrometric Coronagraphs (LASCO) aboard the Solar and Heliospheric Observatory (SOHO). In addition to the O VI and C III lines typical of UVCS spectra of CMEs, this 480 km s-1 CME exhibits the forbidden and intercombination lines of O V at λλ1213.8 and 1218.4. The relative intensities of the O V lines represent an accurate electron density diagnostic not generally available at 3.5 Rsolar. By combining the density with the column density derived from LASCO, we obtain the emission measure of the ejected gas. With the help of models of the temperature and time-dependent ionization state of the expanding gas, we determine a range of heating rates required to account for the UV emission lines. The total thermal energy deposited as the gas travels to 3.5 Rsolar is comparable to the kinetic and gravitational potential energies. We note a core of colder material radiating in C III, surrounded by hotter material radiating in the O V and O VI lines. This concentration of the coolest material into small regions may be a common feature of CMEs. This event thus represents a unique opportunity to describe the morphology of a CME, and to characterize its plasma parameters.

LCROSS Impact Conditions and Ejecta Evolution: Insight from Experiments

NASA Astrophysics Data System (ADS)

Hermalyn, B.; Schultz, P. H.; Colaprete, A.

2009-12-01

The ejecta distribution resulting from an impact event reflects the impact conditions and target material properties. The Lunar CRater Observation and Sensing Satellite (LCROSS) mission will provide a rare look at subsurface materials. The LCROSS impact will excavate regolith from a permanently shadowed crater on the south pole of the moon. The impactor, named the Earth-Departure-Upper-Stage (EDUS), will impact the surface at ~2.5km/s at an angle of greater than 80° from horizontal. The trailing Shepherding Spacecraft (SSc) will record the impact and take measurements of the ejecta in coordination with a comprehensive earth-based observational campaign. Prior studies have explored the predicted ejecta mass/velocity distribution and general ejecta dynamics through computational modeling (Korycansky, et al 2009) and scaling laws(Schultz, 2006, Heldmann et al 2007). At very early times, however, these models and scaling laws break down. It is this high-speed component of the ejected material that will reach the sunlight horizon first and will be recorded by the SSc. Thus to interpret the initial conditions of the impact from the LCROSS ejecta plume, the early-time ejecta distribution must be understood. A suite of impact experiments (performed at the NASA Ames Vertical Gun Range, or AVGR) were designed to interpret LCROSS conditions. These experiments reveal that early in the cratering process, when the projectile is still coupling its energy and momentum to the target surface, ejection velocity is higher than predicted by dimensional scaling laws (Housen, et al 1983). Moreover, the ejection angles of this early-time component are initially lower than predicted, and sweep upward tens of degrees to reach nominal ejection angles (~45° for impacts into sand). Low-density projectiles (such as the EDUS) yield even lower ejection angles throughout much of crater growth, thereby indicating a shallower depth of coupling. An estimate of mass above a given height calculated from these experiments is a factor of ~10 less than predicted by methods above (Korycansky, et al 2009). Analysis of the LCROSS ejecta emergence and evolution, when compared with scaled experimental results, will provide an understanding of the impact conditions as well as constraints on the properties of the regolith.

Radiation From Solar Activity | Radiation Protection | US EPA

EPA Pesticide Factsheets

2017-08-07

Solar flares, coronal mass ejections (CMEs) and geomagnetic storms from the sun can send extreme bursts of ionizing radiation and magnetic energy toward Earth. Some of this energy is in the form ionizing radiation and some of the energy is magnetic energy.

Lunar orbital mass spectrometer experiment

NASA Technical Reports Server (NTRS)

Lord, W. P.

1971-01-01

The design, development, manufacture, test and calibration of five lunar orbital mass spectrometers with the four associated ground support equipment test sets are discussed. A mass spectrometer was installed in the Apollo 15 and one in the Apollo 16 Scientific Instrument Module within the Service Module. The Apollo 15 mass spectrometer was operated with collection of 38 hours of mass spectra data during lunar orbit and 50 hours of data were collected during transearth coast. The Apollo 16 mass spectrometer was operated with collection of 76 hours of mass spectra data during lunar orbit. However, the Apollo 16 mass spectrometer was ejected into lunar orbit upon malfunction of spacecraft boom system just prior to transearth insection and no transearth coast data was possible.

LASCO White-Light Observations of Eruptive Current Sheets Trailing CMEs

NASA Astrophysics Data System (ADS)

Webb, David F.; Vourlidas, Angelos

2016-12-01

Many models of eruptive flares or coronal mass ejections (CMEs) involve formation of a current sheet connecting the ejecting CME flux rope with a magnetic loop arcade. However, there is very limited observational information on the properties and evolution of these structures, hindering progress in understanding eruptive activity from the Sun. In white-light images, narrow coaxial rays trailing the outward-moving CME have been interpreted as current sheets. Here, we undertake the most comprehensive statistical study of CME-rays to date. We use SOHO/LASCO data, which have a higher cadence, larger field of view, and better sensitivity than any previous coronagraph. We compare our results to a previous study of Solar Maximum Mission (SMM) CMEs, in 1984 - 1989, having candidate magnetic disconnection features at the CME base, about half of which were followed by coaxial bright rays. We examine all LASCO CMEs during two periods of minimum and maximum activity in Solar Cycle 23, resulting in many more events, ˜130 CME-rays, than during SMM. Important results include: The occurrence rate of the rays is ˜11 % of all CMEs during solar minimum, but decreases to ˜7 % at solar maximum; this is most likely related to the more complex coronal background. The rays appear on average 3 - 4 hours after the CME core, and are typically visible for three-fourths of a day. The mean observed current sheet length over the ray lifetime is ˜12 R_{⊙}, with the longest current sheet of 18.5 R_{⊙}. The mean CS growth rates are 188 km s^{-1} at minimum and 324 km s^{-1} at maximum. Outward-moving blobs within several rays, which are indicative of reconnection outflows, have average velocities of ˜350 km s^{-1} with small positive accelerations. A pre-existing streamer is blown out in most of the CME-ray events, but half of these are observed to reform within ˜1 day. The long lifetime and long lengths of the CME-rays challenge our current understanding of the evolution of the magnetic field in the aftermath of CMEs.

The metal enrichment of passive galaxies in cosmological simulations of galaxy formation

NASA Astrophysics Data System (ADS)

Okamoto, Takashi; Nagashima, Masahiro; Lacey, Cedric G.; Frenk, Carlos S.

2017-02-01

Massive early-type galaxies have higher metallicities and higher ratios of α elements to iron than their less massive counterparts. Reproducing these correlations has long been a problem for hierarchical galaxy formation theory, both in semi-analytic models and cosmological hydrodynamic simulations. We show that a simulation in which gas cooling in massive dark haloes is quenched by radio-mode active galactic nuclei (AGNs) feedback naturally reproduces the observed trend between α/Fe and the velocity dispersion of galaxies, σ. The quenching occurs earlier for more massive galaxies. Consequently, these galaxies complete their star formation before α/Fe is diluted by the contribution from Type Ia supernovae. For galaxies more massive than ˜1011 M⊙, whose α/Fe correlates positively with stellar mass, we find an inversely correlated mass-metallicity relation. This is a common problem in simulations in which star formation in massive galaxies is quenched either by quasar- or radio-mode AGN feedback. The early suppression of gas cooling in progenitors of massive galaxies prevents them from recapturing enriched gas ejected as winds. Simultaneously reproducing the [α/Fe]-σ relation and the mass-metallicity relation is, thus, difficult in the current framework of galaxy formation.

Effect of valsartan on systemic right ventricular function: a double-blind, randomized, placebo-controlled pilot trial.

PubMed

van der Bom, Teun; Winter, Michiel M; Bouma, Berto J; Groenink, Maarten; Vliegen, Hubert W; Pieper, Petronella G; van Dijk, Arie P J; Sieswerda, Gertjan T; Roos-Hesselink, Jolien W; Zwinderman, Aeilko H; Mulder, Barbara J M

2013-01-22

The role of angiotensin II receptor blockers in patients with a systemic right ventricle has not been elucidated. We conducted a multicenter, double-blind, parallel, randomized controlled trial of angiotensin II receptor blocker valsartan 160 mg twice daily compared with placebo in patients with a systemic right ventricle caused by congenitally or surgically corrected transposition of the great arteries. The primary end point was change in right ventricular ejection fraction during 3-year follow-up, determined by cardiovascular magnetic resonance imaging or, in patients with contraindication for magnetic resonance imaging, multirow detector computed tomography. Secondary end points were change in right ventricular volumes and mass, Vo(2)peak, and quality of life. Primary analyses were performed on an intention-to-treat basis. A total of 88 patients (valsartan, n=44; placebo, n=44) were enrolled in the trial. No serious adverse effects occurred in either group. There was no significant effect of 3-year valsartan therapy on systemic right ventricular ejection fraction (treatment effect, 1.3%; 95% confidence interval, -1.3% to 3.9%; P=0.34), maximum exercise capacity, or quality of life. There was a larger increase in right ventricular end-diastolic volume (15 mL; 95% confidence interval, 3-28 mL; P<0.01) and mass (8 g; 95% confidence interval, 2-14 g; P=0.01) in the placebo group than in the valsartan group. There was no significant treatment effect of valsartan on right ventricular ejection fraction, exercise capacity, or quality of life. Valsartan was associated with a similar frequency of significant clinical events as placebo. Small but significant differences between valsartan and placebo were present for change in right ventricular volumes and mass. URL: http://www.controlled-trials.com. Unique identifier: ISRCTN52352170.

Secondary ion formation during electronic and nuclear sputtering of germanium

NASA Astrophysics Data System (ADS)

Breuer, L.; Ernst, P.; Herder, M.; Meinerzhagen, F.; Bender, M.; Severin, D.; Wucher, A.

2018-06-01

Using a time-of-flight mass spectrometer attached to the UNILAC beamline located at the GSI Helmholtz Centre for Heavy Ion Research, we investigate the formation of secondary ions sputtered from a germanium surface under irradiation by swift heavy ions (SHI) such as 5 MeV/u Au by simultaneously recording the mass spectra of the ejected secondary ions and their neutral counterparts. In these experiments, the sputtered neutral material is post-ionized via single photon absorption from a pulsed, intensive VUV laser. After post-ionization, the instrument cannot distinguish between secondary ions and post-ionized neutrals, so that both signals can be directly compared in order to investigate the ionization probability of different sputtered species. In order to facilitate an in-situ comparison with typical nuclear sputtering conditions, the system is also equipped with a conventional rare gas ion source delivering a 5 keV argon ion beam. For a dynamically sputter cleaned surface, it is found that the ionization probability of Ge atoms and Gen clusters ejected under electronic sputtering conditions is by more than an order of magnitude higher than that measured for keV sputtered particles. In addition, the mass spectra obtained under SHI irradiation show prominent signals of GenOm clusters, which are predominantly detected as positive or negative secondary ions. From the m-distribution for a given Ge nuclearity n, one can deduce that the sputtered material must originate from a germanium oxide matrix with approximate GeO stoichiometry, probably due to residual native oxide patches even at the dynamically cleaned surface. The results clearly demonstrate a fundamental difference between the ejection and ionization mechanisms in both cases, which is interpreted in terms of corresponding model calculations.

3D Polarized Imaging of Coronal Mass Ejections: Chirality of a CME

NASA Astrophysics Data System (ADS)

DeForest, C. E.; de Koning, C. A.; Elliott, H. A.

2017-12-01

We report on a direct polarimetric determination of the chirality of a coronal mass ejection (CME), using the physics of Thomson scattering applied to synoptic polarized images from the Solar Terrestrial Relations Observatories/COR2 coronagraph. We confirmed the determination using in situ magnetic field measurements of the same CME with the ACE spacecraft. CME chirality is related to the helicity ejected from the solar corona along with the mass and field entrained in the CME. It is also important to prediction of the space-weather-relevant Z component of the CME magnetic field. Hence, remote measurement of CME chirality is an important step toward both understanding CME physics and predicting geoeffectiveness of individual CMEs. The polarimetric properties of Thomson scattering are well known and can, in principle, be used to measure the 3D structure of imaged objects in the solar corona and inner heliosphere. However, reduction of that principle to practice has been limited by the twin difficulties of background subtraction and the signal-to-noise ratio in coronagraph data. Useful measurements of the 3D structure require relative photometry at a few percent precision level in each linear polarization component of the K corona. This corresponds to a relative photometric precision of order 10-4 in direct images of the sky before subtraction of the F corona and related signal. Our measurement was enabled by recent developments in signal processing, which enable a better separation of the photometric signal from noise in the synoptic COR2 data. We discuss the relevance of this demonstration measurement to future instrument requirements, and to the future measurements of 3D structures in CMEs and other solar wind features.

A panchromatic view of the restless SN 2009ip reveals the explosive ejection of a massive star envelope

DOE PAGES

Margutti, R.; Milisavljevic, D.; Soderberg, A. M.; ...

2013-12-10

The double explosion of SN 2009ip in 2012 raises questions about our understanding of the late stages of massive star evolution. We present a comprehensive study of SN 2009ip during its remarkable rebrightenings. High-cadence photometric and spectroscopic observations from the GeV to the radio band obtained from a variety of ground-based and space facilities (including the Very Large Array, Swift, Fermi, Hubble Space Telescope, and XMM) constrain SN 2009ip to be a low energy (E ~ 10 50 erg for an ejecta mass ~0.5 M⊙) and asymmetric explosion in a complex medium shaped by multiple eruptions of the restless progenitormore » star. Most of the energy is radiated as a result of the shock breaking out through a dense shell of material located at ~5 × 10 14 cm with M ~ 0.1 M⊙, ejected by the precursor outburst ~40 days before the major explosion. Here, we interpret the NIR excess of emission as signature of material located further out, the origin of which has to be connected with documented mass-loss episodes in the previous years. This modeling predicts bright neutrino emission associated with the shock break-out if the cosmic-ray energy is comparable to the radiated energy. We connect this phenomenology with the explosive ejection of the outer layers of the massive progenitor star, which later interacted with material deposited in the surroundings by previous eruptions. In future observations will reveal if the massive luminous progenitor star survived. Irrespective of whether the explosion was terminal, SN 2009ip brought to light the existence of new channels for sustained episodic mass loss, the physical origin of which has yet to be identified.« less

Analysis of EIT/LASCO Observations Using Available MHD Models: Investigation of CME Initiation Propagation and Geoeffectiveness

NASA Technical Reports Server (NTRS)

Wu, S. T.

2001-01-01

The Sun's activity drives the variability of geospace (i.e., near-earth environment). Observations show that the ejection of plasma from the sun, called coronal mass ejections (CMEs), are the major cause of geomagnetic storms. This global-scale solar dynamical feature of coronal mass ejection was discovered almost three decades ago by the use of space-borne coronagraphs (OSO-7, Skylab/ATM and P78-1). Significant progress has been made in understanding the physical nature of the CMEs. Observations show that these global-scale CMEs have size in the order of a solar radius (approximately 6.7 x 10(exp 5) km) near the sun, and each event involves a mass of about 10(exp 15) g and an energy comparable to that of a large flare on the order of 10(exp 32) ergs. The radial propagation speeds of CMEs have a wide range from tens to thousands of kilometers per second. Thus, the transit time to near earth's environment [i.e., 1 AU (astronomical unit)] can be as fast as 40 hours to 100 hours. The typical transit time for geoeffective events is approximately 60-80 h. This paper consists of two parts: 1) A summary of the observed CMEs from Skylab to the present SOHO will be presented. Special attention will be made to SOHO/ LASCO/ EIT observations and their characteristics leading to a geoeffectiv a CME 2) The chronological development of theory and models to interpret the physical nature of this fascinating phenomenon will be reviewed. Finally, an example will be presented to illustrate the geoeffectiveness of the CMEs by using both observation and model.

A Sun-to-Earth Analysis of Magnetic Helicity of the 2013 March 17–18 Interplanetary Coronal Mass Ejection

NASA Astrophysics Data System (ADS)

Pal, Sanchita; Gopalswamy, Nat; Nandy, Dibyendu; Akiyama, Sachiko; Yashiro, Seiji; Makela, Pertti; Xie, Hong

2017-12-01

We compare the magnetic helicity in the 2013 March 17–18 interplanetary coronal mass ejection (ICME) flux rope at 1 au and in its solar counterpart. The progenitor coronal mass ejection (CME) erupted on 2013 March 15 from NOAA active region 11692 and is associated with an M1.1 flare. We derive the source region reconnection flux using the post-eruption arcade (PEA) method that uses the photospheric magnetogram and the area under the PEA. The geometrical properties of the near-Sun flux rope is obtained by forward-modeling of white-light CME observations. Combining the geometrical properties and the reconnection flux, we extract the magnetic properties of the CME flux rope. We derive the magnetic helicity of the flux rope using its magnetic and geometric properties obtained near the Sun and at 1 au. We use a constant-α force-free cylindrical flux rope model fit to the in situ observations in order to derive the magnetic and geometric information of the 1 au ICME. We find a good correspondence in both amplitude and sign of the helicity between the ICME and the CME, assuming a semi-circular (half torus) ICME flux rope with a length of π au. We find that about 83% of the total flux rope helicity at 1 au is injected by the magnetic reconnection in the low corona. We discuss the effect of assuming flux rope length in the derived value of the magnetic helicity. This study connecting the helicity of magnetic flux ropes through the Sun–Earth system has important implications for the origin of helicity in the interplanetary medium and the topology of ICME flux ropes at 1 au and hence their space weather consequences.

Multi-point Shock and Flux Rope Analysis of Multiple Interplanetary Coronal Mass Ejections around 2010 August 1 in the Inner Heliosphere

NASA Astrophysics Data System (ADS)

Möstl, C.; Farrugia, C. J.; Kilpua, E. K. J.; Jian, L. K.; Liu, Y.; Eastwood, J. P.; Harrison, R. A.; Webb, D. F.; Temmer, M.; Odstrcil, D.; Davies, J. A.; Rollett, T.; Luhmann, J. G.; Nitta, N.; Mulligan, T.; Jensen, E. A.; Forsyth, R.; Lavraud, B.; de Koning, C. A.; Veronig, A. M.; Galvin, A. B.; Zhang, T. L.; Anderson, B. J.

2012-10-01

We present multi-point in situ observations of a complex sequence of coronal mass ejections (CMEs) which may serve as a benchmark event for numerical and empirical space weather prediction models. On 2010 August 1, instruments on various space missions, Solar Dynamics Observatory/Solar and Heliospheric Observatory/Solar-TErrestrial-RElations-Observatory (SDO/SOHO/STEREO), monitored several CMEs originating within tens of degrees from the solar disk center. We compare their imprints on four widely separated locations, spanning 120° in heliospheric longitude, with radial distances from the Sun ranging from MESSENGER (0.38 AU) to Venus Express (VEX, at 0.72 AU) to Wind, ACE, and ARTEMIS near Earth and STEREO-B close to 1 AU. Calculating shock and flux rope parameters at each location points to a non-spherical shape of the shock, and shows the global configuration of the interplanetary coronal mass ejections (ICMEs), which have interacted, but do not seem to have merged. VEX and STEREO-B observed similar magnetic flux ropes (MFRs), in contrast to structures at Wind. The geomagnetic storm was intense, reaching two minima in the Dst index (≈ - 100 nT), and was caused by the sheath region behind the shock and one of two observed MFRs. MESSENGER received a glancing blow of the ICMEs, and the events missed STEREO-A entirely. The observations demonstrate how sympathetic solar eruptions may immerse at least 1/3 of the heliosphere in the ecliptic with their distinct plasma and magnetic field signatures. We also emphasize the difficulties in linking the local views derived from single-spacecraft observations to a consistent global picture, pointing to possible alterations from the classical picture of ICMEs.

GENESIS OF INTERPLANETARY INTERMITTENT TURBULENCE: A CASE STUDY OF ROPE–ROPE MAGNETIC RECONNECTION

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

Chian, Abraham C.-L.; Loew, Murray H.; Feng, Heng Q.

In a recent paper, the relation between current sheet, magnetic reconnection, and turbulence at the leading edge of an interplanetary coronal mass ejection was studied. We report here the observation of magnetic reconnection at the interface region of two interplanetary magnetic flux ropes. The front and rear boundary layers of three interplanetary magnetic flux ropes are identified, and the structures of magnetic flux ropes are reconstructed by the Grad–Shafranov method. A quantitative analysis of the reconnection condition and the degree of intermittency reveals that rope–rope magnetic reconnection is the most likely site for genesis of interplanetary intermittency turbulence in this event.more » The dynamic pressure pulse resulting from this reconnection triggers the onset of a geomagnetic storm.« less

A coronagraph for operational space weather predication

NASA Astrophysics Data System (ADS)

Middleton, Kevin F.

2017-09-01

Accurate prediction of the arrival of solar wind phenomena, in particular coronal mass ejections (CMEs), at Earth, and possibly elsewhere in the heliosphere, is becoming increasingly important given our ever-increasing reliance on technology. The potentially severe impact on human technological systems of such phenomena is termed space weather. A coronagraph is arguably the instrument that provides the earliest definitive evidence of CME eruption; from a vantage point on or near the Sun-Earth line, a coronagraph can provide near-definitive identification of an Earth-bound CME. Currently, prediction of CME arrival is critically dependent on ageing science coronagraphs whose design and operation were not optimized for space weather services. We describe the early stages of the conceptual design of SCOPE (the Solar Coronagraph for OPErations), optimized to support operational space weather services.

Structure and Dynamics of the Solar Corona

NASA Technical Reports Server (NTRS)

Schnack, D. D.

1994-01-01

Advanced computational techniques were used to study solar coronal heating and coronal mass ejections. A three dimensional, time dependent resistive magnetohydrodynamic code was used to study the dynamic response of a model corona to continuous, slow, random magnetic footpoint displacements in the photosphere. Three dimensional numerical simulations of the response of the corona to simple smooth braiding flows in the photosphere were calculated to illustrate and understand the spontaneous formation of current filaments. Two dimensional steady state helmet streamer configurations were obtained by determining the time asymptotic state of the interaction of an initially one dimensinal transponic solar wind with a spherical potential dipole field. The disruption of the steady state helmet streamer configuration was studied as a response to shearing of the magnetic footpoints of the closed field lines under the helmet.

A study of emergency American football helmet removal techniques.

PubMed

Swartz, Erik E; Mihalik, Jason P; Decoster, Laura C; Hernandez, Adam E

2012-09-01

The purpose was to compare head kinematics between the Eject Helmet Removal System and manual football helmet removal. This quasi-experimental study was conducted in a controlled laboratory setting. Thirty-two certified athletic trainers (sex, 19 male and 13 female; age, 33 ± 10 years; height, 175 ± 12 cm; mass, 86 ± 20 kg) removed a football helmet from a healthy model under 2 conditions: manual helmet removal and Eject system helmet removal. A 6-camera motion capture system recorded 3-dimensional head position. Our outcome measures consisted of the average angular velocity and acceleration of the head in each movement plane (sagittal, frontal, and transverse), the resultant angular velocity and acceleration, and total motion. Paired-samples t tests compared each variable across the 2 techniques. Manual helmet removal elicited greater average angular velocity in the sagittal and transverse planes and greater resultant angular velocity compared with the Eject system. No differences were observed in average angular acceleration in any single plane of movement; however, the resultant angular acceleration was greater during manual helmet removal. The Eject Helmet Removal System induced greater total head motion. Although the Eject system created more motion at the head, removing a helmet manually resulted in more sudden perturbations as identified by resultant velocity and acceleration of the head. The implications of these findings relate to the care of all cervical spine-injured patients in emergency medical settings, particularly in scenarios where helmet removal is necessary. Copyright © 2012 Elsevier Inc. All rights reserved.

Angular momentum exchange in white dwarf binaries accreting through direct impact

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

Sepinsky, J. F.; Kalogera, V., E-mail: jeremy.sepinsky@scranton.edu, E-mail: vicky@northwestern.edu

We examine the exchange of angular momentum between the component spins and the orbit in semi-detached double white dwarf binaries undergoing mass transfer through direct impact of the transfer stream. We approximate the stream as a series of discrete massive particles ejected in the ballistic limit at the inner Lagrangian point of the donor toward the accretor. This work improves upon similar earlier studies in a number of ways. First, we self-consistently calculate the total angular momentum of the orbit at all times. This includes changes in the orbital angular momentum during the ballistic trajectory of the ejected mass, asmore » well as changes during the ejection/accretion due to the radial component of the particle's velocity. Second, we calculate the particle's ballistic trajectory for each system, which allows us to determine the precise position and velocity of the particle upon accretion. We can then include specific information about the radius of the accretor as well as the angle of impact. Finally, we ensure that the total angular momentum is conserved, which requires the donor star spin to vary self-consistently. With these improvements, we calculate the angular momentum change of the orbit and each binary component across the entire parameter space of direct impact double white dwarf binary systems. We find a significant decrease in the amount of angular momentum removed from the orbit during mass transfer, as well as cases where this process increases the angular momentum of the orbit at the expense of the spin angular momentum of the donor. We conclude that, unlike earlier claims in the literature, mass transfer through direct impact need not destabilize the binary and that the quantity and sign of the orbital angular momentum transfer depends on the binary properties, particularly the masses of the double white dwarf binary component stars. This stabilization may significantly impact the population synthesis calculations of the expected numbers of events/systems for which double white dwarfs may be a progenitor, e.g., Type Ia supernovae, Type.Ia supernovae, and AM CVn.« less

Ejection mechanics and trajectory of the ascospores of Gibberella zeae (anamorph Fuarium graminearum).

PubMed

Trail, Frances; Gaffoor, Iffa; Vogel, Steven

2005-06-01

Since wind speed drops to zero at a surface, forced ejection should facilitate spore dispersal. But for tiny spores, with low mass relative to surface area, high ejection speed yields only a short range trajectory, so pernicious is their drag. Thus, achieving high speeds requires prodigious accelerations. In the ascomycete Gibberella zeae, we determined the launch speed and kinetic energy of ascospores shot from perithecia, and the source and magnitude of the pressure driving the launch. We asked whether the pressure inside the ascus suffices to account for launch speed and energy. Launch speed was 34.5 ms-1, requiring a pressure of 1.54 MPa and an acceleration of 870,000 g--the highest acceleration reported in a biological system. This analysis allows us to discount the major sugar component of the epiplasmic fluid, mannitol, as having a key role in driving discharge, and supports the role of potassium ion flux in the mechanism.

Understanding Coronal Dimming and its Relation to Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Mason, J. P.; Woods, T. N.; Caspi, A.; Hock, R. A.

2013-12-01

When extreme ultraviolet (EUV) emitting material in the corona is lost during a coronal mass ejection (CME), the solar spectral irradiance is impacted and these effects are observed in data from the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE) and Atmospheric Imaging Assembly (AIA). This process is one of the physical mechanisms that can lead to the observation of 'coronal dimming,' a phenomenon lasting eight hours on average and rarely persisting longer than one day. Other mechanisms that can cause observed dimming include obscuration of bright material (e.g., flare arcade) by dark material (e.g., filament), temperature evolution (e.g., cool plasma being heated causing transient decreases in characteristic emission lines), and propagation of global waves. Each of these processes has a unique spectral signature, which will be explained and exemplified. In particular, the 7 August 2010 M1.0 flare with associated ~870 km/s CME will be analyzed in detail using both AIA and EVE to demonstrate new techniques for isolating dimming due to the CME ('core dimming'). Further analysis will estimate CME mass and velocity using only parameterization of core dimming and compare these estimates to traditionally calculated CME kinetics.

NEW OBSERVATION OF FAILED FILAMENT ERUPTIONS: THE INFLUENCE OF ASYMMETRIC CORONAL BACKGROUND FIELDS ON SOLAR ERUPTIONS

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

Liu, Y.; Xu, Z.; Su, J.

2009-05-01

Failed filament eruptions not associated with a coronal mass ejection (CME) have been observed and reported as evidence for solar coronal field confinement on erupting flux ropes. In those events, each filament eventually returns to its origin on the solar surface. In this Letter, a new observation of two failed filament eruptions is reported which indicates that the mass of a confined filament can be ejected to places far from the original filament channel. The jetlike mass motions in the two failed filament eruptions are thought to be due to the asymmetry of the background coronal magnetic fields with respectmore » to the locations of the filament channels. The asymmetry of the coronal fields is confirmed by an extrapolation based on a potential field model. The obvious imbalance between the positive and negative magnetic flux (with a ratio of 1:3) in the bipolar active region is thought to be the direct cause of the formation of the asymmetric coronal fields. We think that the asymmetry of the background fields can not only influence the trajectories of ejecta, but also provide a relatively stronger confinement for flux rope eruptions than the symmetric background fields do.« less

Automatic Determination of the Conic Coronal Mass Ejection Model Parameters

NASA Technical Reports Server (NTRS)

Pulkkinen, A.; Oates, T.; Taktakishvili, A.

2009-01-01

Characterization of the three-dimensional structure of solar transients using incomplete plane of sky data is a difficult problem whose solutions have potential for societal benefit in terms of space weather applications. In this paper transients are characterized in three dimensions by means of conic coronal mass ejection (CME) approximation. A novel method for the automatic determination of cone model parameters from observed halo CMEs is introduced. The method uses both standard image processing techniques to extract the CME mass from white-light coronagraph images and a novel inversion routine providing the final cone parameters. A bootstrap technique is used to provide model parameter distributions. When combined with heliospheric modeling, the cone model parameter distributions will provide direct means for ensemble predictions of transient propagation in the heliosphere. An initial validation of the automatic method is carried by comparison to manually determined cone model parameters. It is shown using 14 halo CME events that there is reasonable agreement, especially between the heliocentric locations of the cones derived with the two methods. It is argued that both the heliocentric locations and the opening half-angles of the automatically determined cones may be more realistic than those obtained from the manual analysis

Theoretical studies of the RS cannum venaticorum stars

NASA Technical Reports Server (NTRS)

Mullan, D. J.

1981-01-01

Four areas of research were investigated: chromospheric modelling; starspot modelling; supersonic transition locus (STL) crossing; and STL crossing and T Tauri phenomena. Relationships among these areas of research are presented. Stellar structure and mass ejection for these stars were examined along with chromospheric analysis.

Detection of Coronal Mass Ejections Using Multiple Features and Space-Time Continuity

NASA Astrophysics Data System (ADS)

Zhang, Ling; Yin, Jian-qin; Lin, Jia-ben; Feng, Zhi-quan; Zhou, Jin

2017-07-01

Coronal Mass Ejections (CMEs) release tremendous amounts of energy in the solar system, which has an impact on satellites, power facilities and wireless transmission. To effectively detect a CME in Large Angle Spectrometric Coronagraph (LASCO) C2 images, we propose a novel algorithm to locate the suspected CME regions, using the Extreme Learning Machine (ELM) method and taking into account the features of the grayscale and the texture. Furthermore, space-time continuity is used in the detection algorithm to exclude the false CME regions. The algorithm includes three steps: i) define the feature vector which contains textural and grayscale features of a running difference image; ii) design the detection algorithm based on the ELM method according to the feature vector; iii) improve the detection accuracy rate by using the decision rule of the space-time continuum. Experimental results show the efficiency and the superiority of the proposed algorithm in the detection of CMEs compared with other traditional methods. In addition, our algorithm is insensitive to most noise.

MHD simulations of homologous and cannibalistic coronal mass ejections

NASA Astrophysics Data System (ADS)

Fan, Yuhong; Chatterjee, Piyali

2014-06-01

We present magneto-hydrodynamic simulations of the development of a homologous sequence of coronal mass ejections (CMEs) and demonstrate their so-called cannibalistic behavior. These CMEs originate from the repeated formations and partial eruptions of kink unstable flux ropes as a result of the continued emergence of a twisted flux rope across the lower boundary into a pre-existing coronal potential arcade field. The simulations show that a CME erupting into the open magnetic field created by a preceding CME has a higher speed, and therefore tends to be cannibalistic, catching up and merging with the preceding one into a single fast CME. All the CMEs attained speeds of about 1000 km/s as they exit the domain. The reformation of a twisted flux rope after each CME eruption during the sustained flux emergence can naturally explain the X-ray observations of repeated reformations of sigmoids and “sigmoid-under-cusp” configurations at a low-coronal source of homologous CMEs.

Multiplexed operation of a micromachined ultrasonic droplet ejector array.

PubMed

Forbes, Thomas P; Degertekin, F Levent; Fedorov, Andrei G

2007-10-01

A dual-sample ultrasonic droplet ejector array is developed for use as a soft-ionization ion source for multiplexed mass spectrometry (MS). Such a multiplexed ion source aims to reduce MS analysis time for multiple analyte streams, as well as allow for the synchronized ejection of the sample(s) and an internal standard for quantitative results and mass calibration. Multiplexing is achieved at the device level by division of the fluid reservoir and separating the active electrodes of the piezoelectric transducer for isolated application of ultrasonic wave energy to each domain. The transducer is mechanically shaped to further reduce the acoustical crosstalk between the domains. Device design is performed using finite-element analysis simulations and supported by experimental characterization. Isolated ejection of approximately 5 microm diameter water droplets from individual domains in the micromachined droplet ejector array at around 1 MHz frequency is demonstrated by experiments. The proof-of-concept demonstration using a dual-sample device also shows potential for multiplexing with larger numbers of analytes.

Multiplexed operation of a micromachined ultrasonic droplet ejector array

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

Forbes, Thomas P.; Degertekin, F. Levent; Fedorov, Andrei G.

2007-10-15

A dual-sample ultrasonic droplet ejector array is developed for use as a soft-ionization ion source for multiplexed mass spectrometry (MS). Such a multiplexed ion source aims to reduce MS analysis time for multiple analyte streams, as well as allow for the synchronized ejection of the sample(s) and an internal standard for quantitative results and mass calibration. Multiplexing is achieved at the device level by division of the fluid reservoir and separating the active electrodes of the piezoelectric transducer for isolated application of ultrasonic wave energy to each domain. The transducer is mechanically shaped to further reduce the acoustical crosstalk betweenmore » the domains. Device design is performed using finite-element analysis simulations and supported by experimental characterization. Isolated ejection of {approx}5 {mu}m diameter water droplets from individual domains in the micromachined droplet ejector array at around 1 MHz frequency is demonstrated by experiments. The proof-of-concept demonstration using a dual-sample device also shows potential for multiplexing with larger numbers of analytes.« less

White-light coronal mass ejections: A new perspective from LASCO

NASA Technical Reports Server (NTRS)

St.Cyr, O. C.; Howard, R. A.; Simnett, G. M.; Gurman, J. B.; Plunkett, S. P.; Sheeley, N. R., Jr.; Schwenn, R.; Koomen, M. J.; Brueckner, G. E.; Michels, D. J.;

Coronal Structure of a Flaring Region and Associated Coronal Mass Ejection

NASA Technical Reports Server (NTRS)

Kundu, Mukul R.; Manoharan, P. K.

2003-01-01

We report the multiwavelength investigations of an eruptive flare event that occurred on 2001 April 2 at about 11 UT. The manifestations associated with this flare event have been studied from the near-Sun region to about 0.5 AU. The H-alpha images from the Meudon Spectroheliograph reveal a fast spectacular eruption of plasmoids from the flare site to the west and a Moreton wave disturbance propagating toward the south, A bright, fast, wide coronal mass ejection (CME) associated with this eruptive event was imaged by SOHO/LASCO and the remote-sensing interplanetary scintillation technique. The timings and positions of the Type II radio bursts, H-alpha eruption, and CME onset as well as the magnetic field configuration suggest a release of energy at the null point. The results seem to support the "breakout" scenario proposed by Antiochos and coworkers, and they are also suggestive that the energy release is followed by magnetic reconnection between the low-lying loops near the separatrix and the loop system above them.

Analysis of an Interplanetary Coronal Mass Ejection by a Spacecraft Radio Signal: A Case Study

NASA Astrophysics Data System (ADS)

Molera Calvés, G.; Kallio, E.; Cimo, G.; Quick, J.; Duev, D. A.; Bocanegra Bahamón, T.; Nickola, M.; Kharinov, M. A.; Mikhailov, A. G.

2017-11-01

Tracking radio communication signals from planetary spacecraft with ground-based telescopes offers the possibility to study the electron density and the interplanetary scintillation of the solar wind. Observations of the telemetry link of planetary spacecraft have been conducted regularly with ground antennae from the European Very Long Baseline Interferometry Network, aiming to study the propagation of radio signals in the solar wind at different solar elongations and distances from the Sun. We have analyzed the Mars Express spacecraft radio signal phase fluctuations while, based on a 3-D heliosphere plasma simulation, an interplanetary coronal mass ejection (ICME) crossed the radio path during one of our observations on 6 April 2015. Our measurements showed that the phase scintillation indices increased by a factor of 4 during the passage of the ICME. The method presented here confirms that the phase scintillation technique based on spacecraft signals provides information of the properties and propagation of the ICMEs in the heliosphere.

Coronal ``Wave'': Magnetic Footprint of a Coronal Mass Ejection?

NASA Astrophysics Data System (ADS)

Attrill, Gemma D. R.; Harra, Louise K.; van Driel-Gesztelyi, Lidia; Démoulin, Pascal

2007-02-01

We investigate the properties of two ``classical'' EUV Imaging Telescope (EIT) coronal waves. The two source regions of the associated coronal mass ejections (CMEs) possess opposite helicities, and the coronal waves display rotations in opposite senses. We observe deep core dimmings near the flare site and also widespread diffuse dimming, accompanying the expansion of the EIT wave. We also report a new property of these EIT waves, namely, that they display dual brightenings: persistent ones at the outermost edge of the core dimming regions and simultaneously diffuse brightenings constituting the leading edge of the coronal wave, surrounding the expanding diffuse dimmings. We show that such behavior is consistent with a diffuse EIT wave being the magnetic footprint of a CME. We propose a new mechanism where driven magnetic reconnections between the skirt of the expanding CME magnetic field and quiet-Sun magnetic loops generate the observed bright diffuse front. The dual brightenings and the widespread diffuse dimming are identified as innate characteristics of this process.

Dynamic simulation of coronal mass ejections

NASA Technical Reports Server (NTRS)

Steinolfson, R. S.; Wu, S. T.

1980-01-01

A model is developed for the formation and propagation through the lower corona of the loop-like coronal transients in which mass is ejected from near the solar surface to the outer corona. It is assumed that the initial state for the transient is a coronal streamer. The initial state for the streamer is a polytropic, hydrodynamic solution to the steady-state radial equation of motion coupled with a force-free dipole magnetic field. The numerical solution of the complete time-dependent equations then gradually approaches a stationary coronal streamer configuration. The streamer configuration becomes the initial state for the coronal transient. The streamer and transient simulations are performed completely independent of each other. The transient is created by a sudden increase in the pressure at the base of the closed-field region in the streamer configuration. Both coronal streamers and coronal transients are calculated for values of the plasma beta (the ratio of thermal to magnetic pressure) varying from 0.1 to 100.

Effect on the Lunar Exosphere of a CME Passage

NASA Technical Reports Server (NTRS)

Killen, Rosemary M.; Hurley, Dana M.; Farrell, William M.; Sarantos, Menelaos

2011-01-01

It has long been recognized that solar wind bombardment onto exposed surfaces in the solar system will produce an energetic component to the exospheres about those bodies. Laboratory experiments have shown that the sputter yield can be noticeably increased in the case of a good insulating surface. It is now known that the solar wind composition is highly dependent on the origin of the particular plasma. Using the measured composition of the slow wind, fast wind, solar energetic particle (SEP) population, and coronal mass ejection (CME), broken down into its various components, we have estimated the total sputter yield for each type of solar wind. The heavy ion component, especially the He++ component, greatly enhances the total sputter yield during times when the heavy ion population is enhanced, most notably during a coronal mass ejection. To simulate the effect on the lunar exosphere of a CME passage past the Moon, we ran a Monte Carlo code for the species Na, K, Mg and Ca.

Stars with relativistic speeds in the Hills scenario

NASA Astrophysics Data System (ADS)

Dremova, G. N.; Dremov, V. V.; Tutukov, A. V.

2017-07-01

The dynamical capture of a binary system consisting of a supermassive black hole (SMBH) and an ordinary star in the gravitational field of a central (more massive) SMBH is considered in the three-body problem in the framework of a modified Hills scenario. The results of numerical simulations predict the existence of objects whose spatial speeds are comparable to the speed of light. The conditions for and constraints imposed on the ejection speeds realized in a classical scenario and the modified Hills scenario are analyzed. The star is modeled using an N-body approach, making it possible to treat it as a structured object, enabling estimation of the probability that the object survives when it is ejected with relativistic speed as a function of the mass of the star, the masses of both SMBHs, and the pericenter distance. It is possible that the modern kinematic classification for stars with anomalously high spatial velocities will be augmented with a new class—stars with relativistic speeds.

The Origin of Sequential Chromospheric Brightenings

NASA Astrophysics Data System (ADS)

Kirk, M. S.; Balasubramaniam, K. S.; Jackiewicz, J.; Gilbert, H. R.

2017-06-01

Sequential chromospheric brightenings (SCBs) are often observed in the immediate vicinity of erupting flares and are associated with coronal mass ejections. Since their initial discovery in 2005, there have been several subsequent investigations of SCBs. These studies have used differing detection and analysis techniques, making it difficult to compare results between studies. This work employs the automated detection algorithm of Kirk et al. (Solar Phys. 283, 97, 2013) to extract the physical characteristics of SCBs in 11 flares of varying size and intensity. We demonstrate that the magnetic substructure within the SCB appears to have a significantly smaller area than the corresponding Hα emission. We conclude that SCBs originate in the lower corona around 0.1 R_{⊙} above the photosphere, propagate away from the flare center at speeds of 35 - 85 km s^{-1}, and have peak photosphere magnetic intensities of 148±2.9 G. In light of these measurements, we infer SCBs to be distinctive chromospheric signatures of erupting coronal mass ejections.

Observations of an extreme storm in interplanetary space caused by successive coronal mass ejections.

PubMed

Liu, Ying D; Luhmann, Janet G; Kajdič, Primož; Kilpua, Emilia K J; Lugaz, Noé; Nitta, Nariaki V; Möstl, Christian; Lavraud, Benoit; Bale, Stuart D; Farrugia, Charles J; Galvin, Antoinette B

2014-03-18

Space weather refers to dynamic conditions on the Sun and in the space environment of the Earth, which are often driven by solar eruptions and their subsequent interplanetary disturbances. It has been unclear how an extreme space weather storm forms and how severe it can be. Here we report and investigate an extreme event with multi-point remote-sensing and in situ observations. The formation of the extreme storm showed striking novel features. We suggest that the in-transit interaction between two closely launched coronal mass ejections resulted in the extreme enhancement of the ejecta magnetic field observed near 1 AU at STEREO A. The fast transit to STEREO A (in only 18.6 h), or the unusually weak deceleration of the event, was caused by the preconditioning of the upstream solar wind by an earlier solar eruption. These results provide a new view crucial to solar physics and space weather as to how an extreme space weather event can arise from a combination of solar eruptions.

Multi-wave band SMM-VLA observations of an M2 flare and an associated coronal mass ejection

NASA Technical Reports Server (NTRS)

Willson, Robert F.; Lang, Kenneth R.; Schmelz, Joan T.; Gonzalez, Raymond D.; Smith, Kermit L.

1991-01-01

Results are presented of observations of an M2 flare and an associated coronal mass ejection CME by instruments on the SMM as well as by the VLA and other ground-based observatories on September 30, 1988. The multiwave band data show a gradual slowly changing event which lasted several hours. The microwave burst emission was found to originate in compact moderately circularly polarized sources located near the sites of bright H-alpha and soft X-ray emission. These data are combined with estimates of an electron temperature of 1.5 x 10 to the 7th K and an emission measure of about 2.0 x 10 to the 49th/cu cm obtained from Ca XIX and Fe XXV spectra to show that the microwave emission can be attributed to thermal gyrosynchrotron radiation in regions where the magnetic field strength is 425-650 G. The CME acceleration at low altitudes is measured on the basis of ground- and space-based coronagraphs.

THE KELVIN-HELMHOLTZ INSTABILITY AT CORONAL MASS EJECTION BOUNDARIES IN THE SOLAR CORONA: OBSERVATIONS AND 2.5D MHD SIMULATIONS

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

Moestl, U. V.; Temmer, M.; Veronig, A. M., E-mail: ute.moestl@uni-graz.at

2013-03-20

The Atmospheric Imaging Assembly on board the Solar Dynamics Observatory observed a coronal mass ejection with an embedded filament on 2011 February 24, revealing quasi-periodic vortex-like structures at the northern side of the filament boundary with a wavelength of approximately 14.4 Mm and a propagation speed of about 310 {+-} 20 km s{sup -1}. These structures could result from the Kelvin-Helmholtz instability occurring on the boundary. We perform 2.5D numerical simulations of the Kelvin-Helmholtz instability and compare the simulated characteristic properties of the instability with the observations, where we obtain qualitative as well as quantitative accordance. We study the absencemore » of Kelvin-Helmholtz vortex-like structures on the southern side of the filament boundary and find that a magnetic field component parallel to the boundary with a strength of about 20% of the total magnetic field has stabilizing effects resulting in an asymmetric development of the instability.« less

Progenitors of low-luminosity Type II-Plateau supernovae

NASA Astrophysics Data System (ADS)

Lisakov, Sergey M.; Dessart, Luc; Hillier, D. John; Waldman, Roni; Livne, Eli

2018-01-01

The progenitors of low-luminosity Type II-Plateau supernovae (SNe II-P) are believed to be red supergiant (RSG) stars, but there is much disparity in the literature concerning their mass at core collapse and therefore on the main sequence. Here, we model the SN radiation arising from the low-energy explosion of RSG stars of 12, 25 and 27 M⊙ on the main sequence and formed through single star evolution. Despite the narrow range in ejecta kinetic energy (2.5-4.2 × 1050 erg) in our model set, the SN observables from our three models are significantly distinct, reflecting the differences in progenitor structure (e.g. surface radius, H-rich envelope mass and He-core mass). Our higher mass RSG stars give rise to Type II SNe that tend to have bluer colours at early times, a shorter photospheric phase, and a faster declining V-band light curve (LC) more typical of Type II-linear SNe, in conflict with the LC plateau observed for low-luminosity SNe II. The complete fallback of the CO core in the low-energy explosions of our high-mass RSG stars prevents the ejection of any 56Ni (nor any core O or Si), in contrast to low-luminosity SNe II-P, which eject at least 0.001 M⊙ of 56Ni. In contrast to observations, Type II SN models from higher mass RSGs tend to show an H α absorption that remains broad at late times (due to a larger velocity at the base of the H-rich envelope). In agreement with the analyses of pre-explosion photometry, we conclude that low-luminosity SNe II-P likely arise from low-mass rather than high-mass RSG stars.

A hybrid Rayleigh-Taylor-current-driven coupled instability in a magnetohydrodynamically collimated cylindrical plasma with lateral gravity

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

Zhai, Xiang, E-mail: xzhai@caltech.edu; Bellan, Paul M., E-mail: pbellan@caltech.edu

We present an MHD theory of Rayleigh-Taylor instability on the surface of a magnetically confined cylindrical plasma flux rope in a lateral external gravity field. The Rayleigh-Taylor instability is found to couple to the classic current-driven instability, resulting in a new type of hybrid instability that cannot be described by either of the two instabilities alone. The lateral gravity breaks the axisymmetry of the system and couples all azimuthal modes together. The coupled instability, produced by combination of helical magnetic field, curvature of the cylindrical geometry, and lateral gravity, is fundamentally different from the classic magnetic Rayleigh-Taylor instability occurring atmore » a two-dimensional planar interface. The theory successfully explains the lateral Rayleigh-Taylor instability observed in the Caltech plasma jet experiment [Moser and Bellan, Nature 482, 379 (2012)]. Potential applications of the theory include magnetic controlled fusion, solar emerging flux, solar prominences, coronal mass ejections, and other space and astrophysical plasma processes.« less

Evolution of the Black Hole Mass Function in Star Clusters from Multiple Mergers

NASA Astrophysics Data System (ADS)

Christian, Pierre; Mocz, Philip; Loeb, Abraham

2018-05-01

We investigate the effects of black hole (BH) mergers in star clusters on the black hole mass function (BHMF). As BHs are not produced in pair-instability supernovae, it is suggested that there is a dearth of high-mass stellar BHs. This dearth generates a gap in the upper end of the BHMF. Meanwhile, parameter fitting of X-ray binaries suggests the existence of a gap in the mass function under 5 solar masses. We show, through evolving a coagulation equation, that BH mergers can appreciably fill the upper mass gap, and that the lower mass gap generates potentially observable features at larger mass scales. We also explore the importance of ejections in such systems and whether dynamical clusters can be formation sites of intermediate-mass BH seeds.

Disruption of Helmet Streamers by Current Emergence

NASA Technical Reports Server (NTRS)

Guo, W. P.; Wu, S. T.; Tandberg-Hanssen, E.

1996-01-01

We have investigated the dynamic response of a coronal helmet streamer to the emergence from below of a current with its magnetic field in a direction opposite to the overlying streamer field. Once the emerging current moves into the closed region of the streamer, a current sheet forms between the emerging field and the streamer field, because the preexisting field and the newly emerging field have opposite polarities. Thus magnetic reconnection will occur at the flanks of the emerged structure where the current density is maximum. If the emerging current is large enough, the energy contained in the current and the reconnection will promptly disrupt the streamer. If the emerging current is small, the streamer will experience a stage of slow evolution. In this stage, slow magnetic reconnection occurring at the flanks of the emerged structure leads to the degeneration of the emerged current to a neutral point. Above this point, a new magnetic bubble will form. The resulting configuration resembles an inverse-polarity prominence. Depending on the initial input energy of the current, the resulting structure will either remain in situ, forming a quasi-static structure, or move upward, forming a coronal transient similar to coronal jets. The numerical method used in this paper can be used to construct helmet streamers containing a detached magnetic structure in their closed field region. The quasi-static solution may serve as a preevent corona for studying coronal mass ejection initiation.

The magnetospheric and ionospheric response to a very strong interplanetary shock and coronal mass ejection

NASA Astrophysics Data System (ADS)

Ridley, A. J.; De Zeeuw, D. L.; Manchester, W. B.; Hansen, K. C.

2006-01-01

We present results from a coupled magnetospheric and ionospheric simulation of a very strong solar wind shock and coronal mass ejection (CME). The solar wind drivers that are used for this simulation were output from the Sun-to-Earth MHD simulation of the Carrington-like CME reported in Manchester et al. [Manchester IV, W., Ridley, A., Gombosi, T., De Zeeuw, D. Modeling the Sun-Earth propagation of a very fast cme. Adv. Space Res. 38 (this issue), 2006]. We use the University of Michigan's BATS-R-US MHD code to model the global magnetosphere and coupled height integrated ionosphere. As the interplanetary shock swept over the magnetosphere, a wave is observed to propagate through the system. This is evident both in the magnetosphere and ionosphere. On the dayside, the magnetospheric bowshock is shown to bifurcate. The inner shock is pushed close to the inner boundary, where it "bounces" and propagates back outwards to meet the outer bowshock, which is propagating inwards. The inward and outward motion of the bowshocks can be observed propagating down the flanks of the magnetosphere. In the ionosphere, the wave is manifested as two pairs of field-aligned currents moving antisunward. The first pair is opposite of the normal region-1 current system, while the second pair is in the same sense as the normal region-1 system. The ionospheric potential shows a behavior consistent with the field-aligned current pattern, given the strong gradient in the conductance from the dayside to the nightside. As the magnetic cloud flows over the system, the entire magnetopause boundary is observed to move inside of geosynchronous orbit (6.6 Re). At the time of the most extreme solar wind conditions, the magnetopause boundary encounters the inner edge of the magnetospheric simulation domain. During the magnetic cloud, the ionospheric cross-polar cap potential is shown to match the Siscoe et al. [Siscoe, G.L., Erickson, G., Sonnerup, B., Maynard, N., Schoendorf, J., Siebert, K., Weimer, D., White, W., Wilson, G. Hill model of transpolar potential saturation: comparisons with MHD simulations. J. Geophys. Res. 107, 1321, doi:10.1029/2001JA009176, 2002] formulation relating the ionospheric potential to the solar wind and IMF conditions. It is shown that by using this formulation, the extremely large potentials observed in the MHD results are most likely saturated.

Efficient ejection of H3+ from hydrocarbon molecules induced by ultrashort intense lalifeser fields

NASA Astrophysics Data System (ADS)

Hoshina, Kennosuke; Furukawa, Yusuke; Okino, Tomoya; Yamanouchi, Kaoru

2008-09-01

The ejection processes of hydrogen molecular ion H3+ from 12 kinds of hydrocarbon molecular species, methanol, ethanol, 1-propanol, 2-propanol, acetone, acetaldehyde, methane, ethane, ethylene, allene, 1,3-butadiene, and cyclohexane, induced by intense laser fields (˜1014W/cm2) have been investigated by time-of-flight mass spectroscopy. The observation of the H3+ production with the kinetic energy range of 3.5-5.0eV from doubly ionized ethylene, allene, 1,3-butadiene, and cyclohexane, which have no methyl groups, showed the existence of the ultrafast hydrogen migration processes that enables three hydrogen atoms to come together to form H3+ within a hydrocarbon molecule.

Moon-based UV reflecting coronagraph

NASA Astrophysics Data System (ADS)

Vial, J. C.; Koutchmy, S.; Smartt, R. N.

1994-06-01

UV observations of the solar disc, and above the limb, have evidenced a wide range of possible diagnostics, especially in the Lyman alpha line. On the disc, Lyman alpha traces the magnetic (sometimes unexpected) structuring of the top of the atmosphere; out from the limb, it allows measurement of radial velocities up to a few solar radii where most optical techniques fail. Other diagnostics include the kinematics of ejections (e.g. Coronal Mass Ejections (CMEs), but also small-scale rapidly evolving plasmoids). We propose a dual-channel reflecting coronagraph combining relatively-high angular resolution (0.2-0.4 inches) with large spatial (2.5 solar radii from Sun center) and temporal coverage. The advantages offered by a Moon-based instrument are discussed.

Chandra, NuSTAR and NICER Observations of MAXI J1535-571

NASA Astrophysics Data System (ADS)

Neilsen, Joseph; Cackett, Ed; Fabian, Andy; Gendreau, Keith C.; Miller, Jon M.; Pasham, Dheeraj; Remillard, Ron; Steiner, Jack; Uttley, Phil

2018-01-01

In September 2017, MAXI detected an outburst of a previously-unknown transient, MAXI J1535-571. Subsequent radio and X-ray monitoring indicated that the source is a strong black hole candidate. We began a series of monitoring observations with Chandra HETGS, NuSTAR, and NICER to track the evolution of the outburst. Together, these three observatories represent an incredible opportunity to study the geometry of the accretion flow (via continuum spectroscopy), its variation with accretion state (via spectral variability), and any associated outflows or mass ejections (via line spectroscopy). We will present our analysis of this bright outburst and discuss the physics of accretion and ejection in this new black hole candidate.

Solar radio bursts as a tool for space weather forecasting

NASA Astrophysics Data System (ADS)

Klein, Karl-Ludwig; Matamoros, Carolina Salas; Zucca, Pietro

2018-01-01

The solar corona and its activity induce disturbances that may affect the space environment of the Earth. Noticeable disturbances come from coronal mass ejections (CMEs), which are large-scale ejections of plasma and magnetic fields from the solar corona, and solar energetic particles (SEPs). These particles are accelerated during the explosive variation of the coronal magnetic field or at the shock wave driven by a fast CME. In this contribution, it is illustrated how full Sun microwave observations can lead to (1) an estimate of CME speeds and of the arrival time of the CME at the Earth, (2) the prediction of SEP events attaining the Earth. xml:lang="fr"

Transport, Acceleration and Spatial Access of Solar Energetic Particles

NASA Astrophysics Data System (ADS)

Borovikov, D.; Sokolov, I.; Effenberger, F.; Jin, M.; Gombosi, T. I.

2017-12-01

Solar Energetic Particles (SEPs) are a major branch of space weather. Often driven by Coronal Mass Ejections (CMEs), SEPs have a very high destructive potential, which includes but is not limited to disrupting communication systems on Earth, inflicting harmful and potentially fatal radiation doses to crew members onboard spacecraft and, in extreme cases, to people aboard high altitude flights. However, currently the research community lacks efficient tools to predict such hazardous SEP events. Such a tool would serve as the first step towards improving humanity's preparedness for SEP events and ultimately its ability to mitigate their effects. The main goal of the presented research is to develop a computational tool that provides the said capabilities and meets the community's demand. Our model has the forecasting capability and can be the basis for operational system that will provide live information on the current potential threats posed by SEPs based on observations of the Sun. The tool comprises several numerical models, which are designed to simulate different physical aspects of SEPs. The background conditions in the interplanetary medium, in particular, the Coronal Mass Ejection driving the particle acceleration, play a defining role and are simulated with the state-of-the-art MHD solver, Block-Adaptive-Tree Solar-wind Roe-type Upwind Scheme (BATS-R-US). The newly developed particle code, Multiple-Field-Line-Advection Model for Particle Acceleration (M-FLAMPA), simulates the actual transport and acceleration of SEPs and is coupled to the MHD code. The special property of SEPs, the tendency to follow magnetic lines of force, is fully taken advantage of in the computational model, which substitutes a complicated 3-D model with a multitude of 1-D models. This approach significantly simplifies computations and improves the time performance of the overall model. Also, it plays an important role of mapping the affected region by connecting it with the origin of SEPs at the solar surface. Our model incorporates the effects of the near-Sun field line meandering that affects the perpendicular transport of SEPs and can explain the occurrence of large longitudinal spread observed even in the early phases of such events.

Diffraction-limited Visible Light Images of Orion Trapezium Cluster with the Magellan Adaptive Secondary Adaptive Optics System (MagAO)

NASA Astrophysics Data System (ADS)

Close, L. M.; Males, J. R.; Morzinski, K.; Kopon, D.; Follette, K.; Rodigas, T. J.; Hinz, P.; Wu, Y.-L.; Puglisi, A.; Esposito, S.; Riccardi, A.; Pinna, E.; Xompero, M.; Briguglio, R.; Uomoto, A.; Hare, T.

2013-09-01

We utilized the new high-order (250-378 mode) Magellan Adaptive Optics system (MagAO) to obtain very high spatial resolution observations in "visible light" with MagAO's VisAO CCD camera. In the good-median seeing conditions of Magellan (0.''5-0.''7), we find MagAO delivers individual short exposure images as good as 19 mas optical resolution. Due to telescope vibrations, long exposure (60 s) r' (0.63 μm) images are slightly coarser at FWHM = 23-29 mas (Strehl ~28%) with bright (R < 9 mag) guide stars. These are the highest resolution filled-aperture images published to date. Images of the young (~1 Myr) Orion Trapezium θ1 Ori A, B, and C cluster members were obtained with VisAO. In particular, the 32 mas binary θ1 Ori C 1 C 2 was easily resolved in non-interferometric images for the first time. The relative positions of the bright trapezium binary stars were measured with ~0.6-5 mas accuracy. We are now sensitive to relative proper motions of just ~0.2 mas yr-1 (~0.4 km s-1 at 414 pc)—this is a ~2-10 × improvement in orbital velocity accuracy compared to previous efforts. For the first time, we see clear motion of the barycenter of θ1 Ori B 2 B 3 about θ1 Ori B 1. All five members of the θ1 Ori B system appear likely to be a gravitationally bound "mini cluster," but we find that not all the orbits can be both circular and co-planar. The lowest mass member of the θ1 Ori B system (B 4; mass ~0.2 M ⊙) has a very clearly detected motion (at 4.1 ± 1.3 km s-1 correlation = 99.9%) w.r.t. B 1. Previous work has suggested that B 4 and B 3 are on long-term unstable orbits and will be ejected from this "mini cluster." However, our new "baseline" model of the θ1 Ori B system suggests a more hierarchical system than previously thought, and so the ejection of B 4 may not occur for many orbits, and B 3 may be stable against ejection in the long-term. This "ejection" process of the lowest mass member of a "mini cluster" could play a major role in the formation of low-mass stars and brown dwarfs. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Physical and dynamical properties of the anomalous comet 249P/LINEAR

NASA Astrophysics Data System (ADS)

Fernández, Julio A.; Licandro, Javier; Moreno, Fernando; Sosa, Andrea; Cabrera-Lavers, Antonio; de León, Julia; Birtwhistle, Peter

2017-10-01

Images and low-resolution spectra of the near-Earth Jupiter family comet (JFC) 249P/LINEAR in the visible range obtained with the instrument OSIRIS in the 10.4 m Gran Telescopio Canarias (GTC) (La Palma, Spain) on January 3, 4, 6 and February 6, 2016 are presented, together with a series of images obtained with the 0.4m telescope of the Great Shefford Observatory obtained on Oct. 22 and 27, and Nov. 1 and 24, 2006. The reflectance spectrum of 249P is similar to that of a B-type asteroid. The comet has an absolute (visual) nuclear magnitude HV = 17.0 ± 0.4 , which corresponds to a radius of about 1-1.3 km for a geometric albedo ∼ 0.04 - 0.07 . From the analysis of GTC images using a Monte Carlo dust tail code we find that the time of maximum dust ejection rate was around 1.6 days before perihelion. The analysis of the dust tails during the 2006 and 2016 perihelion approaches reveals that, during both epochs, the comet repeated the same dust ejection pattern, with a similar short-lived activity period of about 20 days (FWHM) around perihelion and a dust loss rate peaking at 145 ± 50 kg/s. The total dust mass ejected during its last perihelion passage was (2.5 ± 0.9) × 108 kg, almost all this mass being emitted before the first observation of January 3, 2016. The activity onset, duration, and total ejected mass were very similar during the 2006 perihelion passage. This amount of dust mass is very low as compared with that from other active JFCs. The past orbital evolution of 249P and 100 clones were also followed over a time scale of ∼ 5 × 104 yr. The object and more than 60% of the clones remained bound to the near-Earth region for the whole computed period, keeping its perihelion distance within the range q ≃ 0.4 - 1.1 au. The combination of photometric and spectroscopic observations and dynamical studies show that the near-Earth comet 249P/LINEAR has several peculiar features that clearly differentiate it from typical JFCs. We may be in front of a new class of near-Earth JFC whose source region is not the distant trans-neptunian population, but much closer in the asteroid belt. Therefore, 249P/LINEAR may be a near-Earth counterpart of the so-called main-belt comets or active asteroids.

Observations of the Coronal Mass Ejection with a Complex Acceleration Profile

NASA Astrophysics Data System (ADS)

Reva, A. A.; Kirichenko, A. S.; Ulyanov, A. S.; Kuzin, S. V.

2017-12-01

We study the coronal mass ejection (CME) with a complex acceleration profile. The event occurred on 2009 April 23. It had an impulsive acceleration phase, an impulsive deceleration phase, and a second impulsive acceleration phase. During its evolution, the CME showed signatures of different acceleration mechanisms: kink instability, prominence drainage, flare reconnection, and a CME–CME collision. The special feature of the observations is the usage of the TESIS EUV telescope. The instrument could image the solar corona in the Fe 171 Å line up to a distance of 2 {R}ȯ from the center of the Sun. This allows us to trace the CME up to the LASCO/C2 field of view without losing the CME from sight. The onset of the CME was caused by kink instability. The mass drainage occurred after the kink instability. The mass drainage played only an auxiliary role: it decreased the CME mass, which helped to accelerate the CME. The first impulsive acceleration phase was caused by the flare reconnection. We observed the two-ribbon flare and an increase of the soft X-ray flux during the first impulsive acceleration phase. The impulsive deceleration and the second impulsive acceleration phases were caused by the CME–CME collision. The studied event shows that CMEs are complex phenomena that cannot be explained with only one acceleration mechanism. We should seek a combination of different mechanisms that accelerate CMEs at different stages of their evolution.

Explosive events on the Sun.

PubMed

Harra, Louise K

2002-12-15

I describe two of the most dynamic and highly energetic phenomena in the Solar System--the explosive flares that can occur when plasma is confined by magnetic fields and the large-scale ejections of material known as 'coronal mass ejections'. These explosive events are poorly understood and yet occur in a variety of contexts in the Universe, ranging from planetary magnetospheres to active galactic nuclei. Understanding why flares and coronal mass ejections occur is a major goal across a wide range of space physics and astrophysics. Although explosive events from the Sun have dramatic effects on Earth, flares in other stars, for example, can be vastly more energetic and have an even more profound effect on their environment. We are now in the unprecedented position of having access to a number of space observatories dedicated to the Sun: the Yohkoh spacecraft, the Solar and Heliospheric Observatory, the Transition Region and Coronal Explorer and the Ramaty High Energy Solar Spectroscopic Imager. These cover a wide wavelength range from white light to gamma rays with both spectroscopy and imaging, and allow huge progress to be made in understanding the processes involved in such large explosions. The high-resolution data show dramatic and complex explosions of material on all spatial scales on the Sun. They have revealed that the Sun is constantly changing everywhere on its surface--something that was never imagined before. One of the mechanisms that has been proposed to account for the large energy release is magnetic reconnection. Recent observations from space increasingly support this view. This article will discuss those observations that support this model and also those that suggest different processes. The current space missions have given us an excellent insight into the actual explosive processes in the Sun. However, they have provided us with only a tantalizing glimpse of what causes the elusive trigger. Future missions such as Solar-B (the follow-on to Yohkoh), the Solar Terrestrial Relations Observatory, the Solar Dynamics Observatory and the Solar Orbiter mission will allow us to probe the trigger in a way that was not dreamt of a decade ago, by providing stereo views, measurements from Sun-grazing orbit, and much higher spatial, temporal and spectral resolution. It is an exciting time for solar physics and everything that we learn about the Sun will improve our ability to understand other magnetic phenomena in the Universe.

Predicting Juno Evidence for a Solid Methane Gas Hydrate Jupiter J. Ackerman Abstract

NASA Astrophysics Data System (ADS)

Ackerman, J. A., Jr.

2016-12-01

Predicting Juno Evidence for a Solid Methane Gas Hydrate Jupiter J. Ackerman AbstractDeuterium enhancements of 1010 observed in LDNs and heavy elements detected by the Galileo probe (C, O, S, Ar, Kr and Xe) suggest the giant planets accreted slow and cold from snowflakes and dust at their current orbits, forming frozen, highly deuterated Methane Gas Hydrate (d=0.9) bodies, together comprising > 300 earth masses of water. Jupiter also incorporated most of the heavy elements in the nascent solar system as dust grains (d=1.33). A recent (6,000 years BP) high energy impact on heavily deuterated Jupiter triggered a massive nuclear fusion explosion which ejected the Galilean moons, initiating a flaming plasma plume originally extending 2 x106 km, beyond Callisto. The rapidly rotating plume produced the physical differences observed on the Galilean moons and the remainder condensed ejecting millions of asteroids similar to 67P as it slowly diminished over 5000 years. The fusion reaction has diminished to d + p > 3He+ + γ, but is still producing Jupiter's atmospheric temperature excess, >5x1017 watts, and driving the multiple zonal wind vortices constrained below by Jupiter's solid surface. The mass being ejected by the plume measurably slowed the rotation of the giant Jupiter up until 1937. The highly energetic 3He+ ions from the fusion reaction that exit Jupiter through the Great Red Spot were sensed by Ulysses, Cassini and Galileo at distances greater than 11 Jupiter radii, with the period of Jupiter's rotation. The Juno JEDI particle detector will measure the speed and density of the 3He+ 'blizzard' exiting the GRS, for which there is no other explanation. The Micro Wave Radiometer (MWR) system will confirm the hot vortex extending below the cloud tops from the fusion reaction on the surface westward to the Great Red Spot at 22o S latitude, due to its estimated 115 degree longitudinal extent. The high intensity of the 3He+ particulate radiation at 4000 km directly above the Great Red Spot could disable the MWR system. The Juno Radio Science (gravity) experiment will detect the very large basin or flooded palimpsest surrounding the active fusion impact site and an east-west ice mountain range paralleling the vortex, formed due to the raining out of water as it rises, expands and cools.

THE CHANGE OF THE ORBITAL PERIODS ACROSS ERUPTIONS AND THE EJECTED MASS FOR RECURRENT NOVAE CI AQUILAE AND U SCORPII

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

Schaefer, Bradley E.

2011-12-01

I report on the cumulative results from a program started 24 years ago designed to measure the orbital period change of recurrent novae (RNe) across an eruption. The goal is to use the orbital period change to measure the mass ejected during each eruption as the key part of trying to measure whether the RNe white dwarfs are gaining or losing mass over an entire eruption cycle, and hence whether they can be progenitors for Type Ia supernovae. This program has now been completed for two eclipsing RNe: CI Aquilae (CI Aql) across its eruption in 2000 and U Scorpiimore » (U Sco) across its eruption in 1999. For CI Aql, I present 78 eclipse times from 1991 to 2009 (including four during the tail of the 2000 eruption) plus two eclipses from 1926 and 1935. For U Sco, I present 67 eclipse times, including 46 times during quiescence from 1989 to 2009, plus 21 eclipse times in the tails of the 1945, 1999, and 2010 eruptions. The eclipse times during the tails of eruptions are systematically and substantially shifted with respect to the ephemerides from the eclipses in quiescence, with this being caused by shifts of the center of light during the eruption. These eclipse times are plotted on an O - C diagram and fitted to models with a steady period change ( P-dot ) between eruptions (caused by, for example, conservative mass transfer) plus an abrupt period change ({Delta}P) at the time of eruption. The primary uncertainty arises from the correlation between {Delta}P with P-dot , such that a more negative P-dot makes for a more positive {Delta}P. For CI Aql, the best fit is {Delta}P = -3.7{sup +9.2}{sub -7.3} Multiplication-Sign 10{sup -7}. For U Sco, the best fit is {Delta}P = (+ 43 {+-} 69) Multiplication-Sign 10{sup -7} days. These period changes can directly give a dynamical measure of the mass ejected (M{sub ejecta}) during each eruption with negligible sensitivity to the stellar masses and no uncertainty from distances. For CI Aql, the 1{sigma} upper limit is M{sub ejecta} < 10 Multiplication-Sign 10{sup -7} M{sub Sun }. For U Sco, I derive M{sub ejecta} = (43 {+-} 67) Multiplication-Sign 10{sup -7} M{sub Sun }.« less

Modeling Kicks from the Merger of Generic Black-hole Binaries

NASA Technical Reports Server (NTRS)

Baker, John G.; Boggs, William D.; Centrella, Joan; Kelly, Bernard J.; McWilliams, Sean T.; Miller, M. Coleman; vanMeter, James R.

2008-01-01

Recent numerical relativistic results demonstrate that the merger of comparable-mass spinning black holes has a maximum "recoil kick" of up to approx. 4000 km/s. However the scaling of these recoil velocities with mass ratio is poorly understood. We present new runs showing that the maximum possible kick parallel to the orbital axis does not scale as approx. eta(sup 2) (where eta is the symmetric mass ratio), as previously proposed, but is more consistent with approx. eta(sup 3). We discuss the effect of this dependence on galactic ejection scenarios and retention of intermediate-mass black holes in globular clusters. S

Light weight escape capsule for fighter aircraft

NASA Technical Reports Server (NTRS)

Robert, James A.

1988-01-01

Emergency crew escape capabilities have been less than adequate for fighter aircraft since before WW II. From the over-the-side bailout of those days through the current ejection seat with a rocket catapult, escaping from a disabled aircraft has been risky at best. Current efforts are underway toward developing a high-tech, smart ejection seat that will give fighter pilots more room to live in the sky, but an escape capsule is needed to meet current and future fighter envelopes. Escape capsules have a bad reputation due to past examples of high weight, poor performance and great complexity. However, the advantages available demand that a capsule be developed. This capsule concept will minimize the inherent disavantages and incorporate the benefits while integrating all aspects of crew station design. The resulting design is appropriate for a crew station of the year 2010 and includes improved combat acceleration protection, chemical or biological combat capability, improved aircraft to escape system interaction, and the highest level of escape performance achievable. The capsule is compact, which can allow a reduced aircraft size and weighs only 1200 lb. The escape system weight penalty is only 120 lb higher than that for the next ejection seat and the capsule has a corresponding increase in performance.

The effect of photoelectrons on boom-satellite potential differences during electron beam ejection

NASA Technical Reports Server (NTRS)

Lai, Shu T.; Cohen, Herbert A.; Aggson, Thomas L.; Mcneil, William J.

1987-01-01

Data taken on the SCATHA satellite at geosynchronous altitudes during periods of electron beam ejection in sunlight showed that the potential difference between an electrically isolated boom and the satellite main body was a function of beam current, energy, and boom-sun angle. The potential difference decreased as the boom area illuminated by the sun increased; the maximum and minimum potential differences were measured when minimum and maximum boom areas, respectively, were exposed to the sun. It is shown that photoelectrons, created on the boom, could be engulfed in the electrostatic field of the highly charged satellite main body. Theoretical calculations made using a simple current balance model showed that these electrons could provide a substantial discharging current to the main body and cause the observed variations in the potential difference between the main body and the booms.

Interstudy reproducibility of dimensional and functional measurements between cine magnetic resonance studies in the morphologically abnormal left ventricle.

PubMed

Semelka, R C; Tomei, E; Wagner, S; Mayo, J; Caputo, G; O'Sullivan, M; Parmley, W W; Chatterjee, K; Wolfe, C; Higgins, C B

1990-06-01

The validity of geometric formulas to derive mass and volumes in the morphologically abnormal left ventricle is problematic. Imaging techniques that are tomographic and therefore inherently three-dimensional should be more reliable and reproducible between studies in such ventricles. Determination of reproducibility between studies is essential to define the limits of an imaging technique for evaluating the response to therapy. Sequential cine magnetic resonance (MR) studies were performed on patients with dilated cardiomyopathy (n = 11) and left ventricular hypertrophy (n = 8) within a short interval in order to assess interstudy reproducibility. Left ventricular mass, volumes, ejection fraction, and end-systolic wall stress were determined by two independent observers. Between studies, left ventricular mass was highly reproducible for hypertrophied and dilated ventricles, with percent variability less than 6%. Ejection fraction and end-diastolic volume showed close reproducibility between studies, with percent variability less than 5% End-systolic volume varied by 4.3% and 4.5% in dilated cardiomyopathy and 8.4% and 7.2% in left ventricular hypertrophy for the two observers. End-systolic wall stress, which is derived from multiple measurements, varied the greatest, with percent variability of 17.2% and 15.7% in dilated cardiomyopathy and 14.8% and 13% in left ventricular hypertrophy, respectively. The results of this study demonstrate that mass, volume, and functional measurements are reproducible in morphologically abnormal ventricles.

Height of shock formation in the solar corona inferred from observations of type II radio bursts and coronal mass ejections

NASA Astrophysics Data System (ADS)

Gopalswamy, N.; Xie, H.; Mäkelä, P.; Yashiro, S.; Akiyama, S.; Uddin, W.; Srivastava, A. K.; Joshi, N. C.; Chandra, R.; Manoharan, P. K.; Mahalakshmi, K.; Dwivedi, V. C.; Jain, R.; Awasthi, A. K.; Nitta, N. V.; Aschwanden, M. J.; Choudhary, D. P.

2013-06-01

Employing coronagraphic and EUV observations close to the solar surface made by the Solar Terrestrial Relations Observatory (STEREO) mission, we determined the heliocentric distance of coronal mass ejections (CMEs) at the starting time of associated metric type II bursts. We used the wave diameter and leading edge methods and measured the CME heights for a set of 32 metric type II bursts from solar cycle 24. We minimized the projection effects by making the measurements from a view that is roughly orthogonal to the direction of the ejection. We also chose image frames close to the onset times of the type II bursts, so no extrapolation was necessary. We found that the CMEs were located in the heliocentric distance range from 1.20 to 1.93 solar radii (Rs), with mean and median values of 1.43 and 1.38 Rs, respectively. We conclusively find that the shock formation can occur at heights substantially below 1.5 Rs. In a few cases, the CME height at type II onset was close to 2 Rs. In these cases, the starting frequency of the type II bursts was very low, in the range 25-40 MHz, which confirms that the shock can also form at larger heights. The starting frequencies of metric type II bursts have a weak correlation with the measured CME/shock heights and are consistent with the rapid decline of density with height in the inner corona.

Deflections of Fast Coronal Mass Ejections and the Properties of Associated Solar Energetic Particle Events

NASA Technical Reports Server (NTRS)

Kahler, S. W.; Akiyama, S.; Gopalswamy, N.

2012-01-01

The onset times and peak intensities of solar energetic particle (SEP) events at Earth have long been thought to be influenced by the open magnetic fields of coronal holes (CHs). The original idea was that a CH lying between the solar SEP source region and the magnetic footpoint of the 1 AU observer would result in a delay in onset and/or a decrease in the peak intensity of that SEP event. Recently, Gopalswamy et al. showed that CHs near coronal mass ejection (CME) source regions can deflect fast CMEs from their expected trajectories in space, explaining the appearance of driverless shocks at 1 AU from CMEs ejected near solar central meridian (CM). This suggests that SEP events originating in CME-driven shocks may show variations attributable to CH deflections of the CME trajectories. Here, we use a CH magnetic force parameter to examine possible effects of CHs on the timing and intensities of 41 observed gradual E approx 20 MeV SEP events with CME source regions within 20 deg. of CM. We find no systematic CH effects on SEP event intensity profiles. Furthermore, we find no correlation between the CME leading-edge measured position angles and SEP event properties, suggesting that the widths of CME-driven shock sources of the SEPs are much larger than the CMEs. Independently of the SEP event properties, we do find evidence for significant CME deflections by CH fields in these events

Height of Shock Formation in the Solar Corona Inferred from Observations of Type II Radio Bursts and Coronal Mass Ejections

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Xie, H.; Makela, P.; Yashiro, S.; Akiyama, S.; Uddin, W.; Srivastava, A. K.; Joshi, N. C.; Chandra, R.; Manoharan, P. K.

2013-01-01

Employing coronagraphic and EUV observations close to the solar surface made by the Solar Terrestrial Relations Observatory (STEREO) mission, we determined the heliocentric distance of coronal mass ejections (CMEs) at the starting time of associated metric type II bursts. We used the wave diameter and leading edge methods and measured the CME heights for a set of 32 metric type II bursts from solar cycle 24. We minimized the projection effects by making the measurements from a view that is roughly orthogonal to the direction of the ejection. We also chose image frames close to the onset times of the type II bursts, so no extrapolation was necessary. We found that the CMEs were located in the heliocentric distance range from 1.20 to 1.93 solar radii (Rs), with mean and median values of 1.43 and 1.38 Rs, respectively. We conclusively find that the shock formation can occur at heights substantially below 1.5 Rs. In a few cases, the CME height at type II onset was close to 2 Rs. In these cases, the starting frequency of the type II bursts was very low, in the range 25-40 MHz, which confirms that the shock can also form at larger heights. The starting frequencies of metric type II bursts have a weak correlation with the measured CME/shock heights and are consistent with the rapid decline of density with height in the inner corona.

Turbulence and Heating in the Flank and Wake Regions of a Coronal Mass Ejection

NASA Astrophysics Data System (ADS)

Fan, Siteng; He, Jiansen; Yan, Limei; Tomczyk, Steven; Tian, Hui; Song, Hongqiang; Wang, Linghua; Zhang, Lei

2018-01-01

As a coronal mass ejection (CME) passes, the flank and wake regions are typically strongly disturbed. Various instruments, including the Large Angle and Spectroscopic Coronagraph (LASCO), the Atmospheric Imaging Assembly (AIA), and the Coronal Multi-channel Polarimeter (CoMP), observed a CME close to the east limb on 26 October 2013. A hot ({≈} 10 MK) rising blob was detected on the east limb, with an initial ejection flow speed of {≈} 330 km s^{-1}. The magnetic structures on both sides and in the wake of the CME were strongly distorted, showing initiation of turbulent motions with Doppler-shift oscillations enhanced from {≈} ± 3 km s^{-1} to {≈} ± 15 km s^{-1} and effective thermal velocities from {≈} 30 km s^{-1} to {≈} 60 km s^{-1}, according to the CoMP observations at the Fe xiii line. The CoMP Doppler-shift maps suggest that the turbulence behaved differently at various heights; it showed clear wave-like torsional oscillations at lower altitudes, which are interpreted as the antiphase oscillation of an alternating red/blue Doppler shift across the strands at the flank. The turbulence seems to appear differently in the channels of different temperatures. Its turnover time was {≈} 1000 seconds for the Fe 171 Å channel, while it was {≈} 500 seconds for the Fe 193 Å channel. Mainly horizontal swaying rotations were observed in the Fe 171 Å channel, while more vertical vortices were seen in the Fe 193 Å channel. The differential-emission-measure profiles in the flank and wake regions have two components that evolve differently: the cool component decreased over time, evidently indicating a drop-out of cool materials due to ejection, while the hot component increased dramatically, probably because of the heating process, which is suspected to be a result of magnetic reconnection and turbulence dissipation. These results suggest a new turbulence-heating scenario of the solar corona and solar wind.

Statistical Study of the Early Solar System's Instability with Four, Five, and Six Giant Planets

NASA Astrophysics Data System (ADS)

Nesvorný, David; Morbidelli, Alessandro

2012-10-01

Several properties of the solar system, including the wide radial spacing and orbital eccentricities of giant planets, can be explained if the early solar system evolved through a dynamical instability followed by migration of planets in the planetesimal disk. Here we report the results of a statistical study, in which we performed nearly 104 numerical simulations of planetary instability starting from hundreds of different initial conditions. We found that the dynamical evolution is typically too violent, if Jupiter and Saturn start in the 3:2 resonance, leading to ejection of at least one ice giant from the solar system. Planet ejection can be avoided if the mass of the transplanetary disk of planetesimals was large (M disk >~ 50 M Earth), but we found that a massive disk would lead to excessive dynamical damping (e.g., final e 55 <~ 0.01 compared to present e 55 = 0.044, where e 55 is the amplitude of the fifth eccentric mode in the Jupiter's orbit), and to smooth migration that violates constraints from the survival of the terrestrial planets. Better results were obtained when the solar system was assumed to have five giant planets initially, and one ice giant, with mass comparable to that of Uranus and Neptune, was ejected into interstellar space by Jupiter. The best results were obtained when the ejected planet was placed into the external 3:2 or 4:3 resonance with Saturn and M disk ~= 20 M Earth. The range of possible outcomes is rather broad in this case, indicating that the present solar system is neither a typical nor expected result for a given initial state, and occurs, in best cases, with only a sime5% probability (as defined by the success criteria described in the main text). The case with six giant planets shows interesting dynamics but does offer significant advantages relative to the five-planet case.

A model on CME/Flare initiation: Loss of Equilibrium caused by mass loss of quiescent prominences

NASA Astrophysics Data System (ADS)

Miley, George; Chon Nam, Sok; Kim, Mun Song; Kim, Jik Su

2015-08-01

Coronal Mass Ejections (CMEs) model should give an answer to enough energy storage for giant bulk plasma into interplanetary space to escape against the sun’s gravitation and its explosive eruption. Advocates of ‘Mass Loading’ model (e.g. Low, B. 1996, SP, 167, 217) suggested a simple mechanism of CME initiation, the loss of mass from a prominence anchoring magnetic flux rope, but they did not associate the mass loss with the loss of equilibrium. The catastrophic loss of equilibrium model is considered as to be a prospective CME/Flare model to explain sudden eruption of magnetic flux systems. Isenberg, P. A., et al (1993, ApJ, 417, 368)developed ideal magnetohydrodynamic theory of the magnetic flux rope to show occurrence of catastrophic loss of equilibrium according to increasing magnetic flux transported into corona.We begin with extending their study including gravity on prominence’s material to obtain equilibrium curves in case of given mass parameters, which are the strengths of the gravitational force compared with the characteristic magnetic force. Furthermore, we study quasi-static evolution of the system including massive prominence flux rope and current sheet below it to obtain equilibrium curves of prominence’s height according to decreasing mass parameter in a properly fixed magnetic environment. The curves show equilibrium loss behaviors to imply that mass loss result in equilibrium loss. Released fractions of magnetic energy are greater than corresponding zero-mass case. This eruption mechanism is expected to be able to apply to the eruptions of quiescent prominences, which is located in relatively weak magnetic environment with 105 km of scale length and 10G of photospheric magnetic field.

The Hoffmeister asteroid family

NASA Astrophysics Data System (ADS)

Carruba, V.; Novaković, B.; Aljbaae, S.

2017-03-01

The Hoffmeister family is a C-type group located in the central main belt. Dynamically, it is important because of its interaction with the ν1C nodal secular resonance with Ceres, which significantly increases the dispersion in inclination of family members at a lower semimajor axis. As an effect, the distribution of inclination values of the Hoffmeister family at a semimajor axis lower than its centre is significantly leptokurtic, and this can be used to set constraints on the terminal ejection velocity field of the family at the time it was produced. By performing an analysis of the time behaviour of the kurtosis of the vW component of the ejection velocity field [γ2(vW)], as obtained from Gauss' equations, for different fictitious Hoffmeister families with different values of the ejection velocity field, we were able to exclude that the Hoffmeister family should be older than 335 Myr. Constraints from the currently observed inclination distribution of the Hoffmeister family suggest that its terminal ejection velocity parameter VEJ should be lower than 25 m s-1. Results of a Yarko-YORP Monte Carlo method to family dating, combined with other constraints from inclinations and γ2(vW), indicate that the Hoffmeister family should be 220^{+60}_{-40} Myr old, with an ejection parameter VEJ = 20 ± 5 m s-1.

Revealing the Location of the Mixing Layer in a Hot Bubble

NASA Astrophysics Data System (ADS)

Guerrero, M. A.; Fang, X.; Chu, Y.-H.; Toalá, J. A.; Gruendl, R. A.

2017-10-01

The fast stellar winds can blow bubbles in the circumstellar material ejected from previous phases of stellar evolution. These are found at different scales, from planetary nebulae (PNe) around stars evolving to the white dwarf stage, to Wolf-Rayet (WR) bubbles and up to large-scale bubbles around massive star clusters. In all cases, the fast stellar wind is shock-heated and a hot bubble is produced. Processes of mass evaporation and mixing of nebular material and heat conduction occurring at the mixing layer between the hot bubble and the optical nebula are key to determine the thermal structure of these bubbles and their evolution. In this contribution we review our current understanding of the X-ray observations of hot bubbles in PNe and present the first spatially-resolved study of a mixing layer in a PN.

Formation, Heating And Chemical Enrichment Of The Intracluster Medium

NASA Astrophysics Data System (ADS)

Eckert, Dominique

2017-07-01

The intracluster medium (ICM) contains the majority of the baryons (80-90%) of galaxy clusters and groups. It has been progressively heated up by gravitational and non-gravitational processes since the cluster formation epoch (z 2-3) until it reaches the very high temperatures we see today, i.e. between 10 and 100 million degrees. The global properties of the ICM follow tight scaling laws with halo mass which are shaped both by gravitational and non-gravitational effects (in particular gas cooling and AGN feedback). Finally, we also know that the ICM is enriched in metals which have been ejected from cluster galaxies throughout the cluster formation history. I will give a review of what is currently known about the formation and evolution of the ICM, focusing on the heating processes (shocks, turbulence) and the metal enrichment history of the gas.

Solar and Heliospheric Data Requirements: Going Further Than L1

NASA Technical Reports Server (NTRS)

Szabo, A.

2011-01-01

Current operational space weather forecasting relies on solar wind observations made by the ACE spacecraft located at the L1 point providing 30-40 minutes warning time. Some use is also made of SOHO and STEREO solar imaging that potentially can give multiple days of warning time. However, our understanding of the propagation and evolution of solar wind transients is still limited resulting in a typical timing uncertainty of approximately 10 hours. In order to improve this critical understanding, a number of NASA missions are being planned. Specifically the Solar Probe Plus and Solar Orbiter missions will investigate the inner Heliospheric evolution of coronal mass ejections and the acceleration and propagation of solar energetic particles. In addition, a number of multi-spacecraft concepts have been studied that have the potential to significantly improve the accuracy of long-term space weather forecasts.

New clues to the cause of extended main-sequence turnoffs in intermediate-age star clusters in the Magellanic Clouds

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

Correnti, Matteo; Goudfrooij, Paul; Kalirai, Jason S.

2014-10-01

We use the Wide Field Camera 3 on board the Hubble Space Telescope (HST) to obtain deep, high-resolution images of two intermediate-age star clusters in the Large Magellanic Cloud of relatively low mass (≈10{sup 4} M {sub ☉}) and significantly different core radii, namely NGC 2209 and NGC 2249. For comparison purposes, we also reanalyzed archival HST images of NGC 1795 and IC 2146, two other relatively low-mass star clusters. From the comparison of the observed color-magnitude diagrams with Monte Carlo simulations, we find that the main-sequence turnoff (MSTO) regions in NGC 2209 and NGC 2249 are significantly wider thanmore » that derived from simulations of simple stellar populations, while those in NGC 1795 and IC 2146 are not. We determine the evolution of the clusters' masses and escape velocities from an age of 10 Myr to the present age. We find that differences among these clusters can be explained by dynamical evolution arguments if the currently extended clusters (NGC 2209 and IC 2146) experienced stronger levels of initial mass segregation than the currently compact ones (NGC 2249 and NGC 1795). Under this assumption, we find that NGC 2209 and NGC 2249 have estimated escape velocities, V {sub esc} ≳ 15 km s{sup –1} at an age of 10 Myr, large enough to retain material ejected by slow winds of first-generation stars, while the two clusters that do not feature extended MSTOs have V {sub esc} ≲ 12 km s{sup –1} at that age. These results suggest that the extended MSTO phenomenon can be better explained by a range of stellar ages rather than a range of stellar rotation velocities or interacting binaries.« less

Non-conservative evolution in Algols: where is the matter?

NASA Astrophysics Data System (ADS)

Deschamps, R.; Braun, K.; Jorissen, A.; Siess, L.; Baes, M.; Camps, P.

2015-05-01

Context. There is indirect evidence of non-conservative evolutions in Algols. However, the systemic mass-loss rate is poorly constrained by observations and generally set as a free parameter in binary-star evolution simulations. Moreover, systemic mass loss may lead to observational signatures that still need to be found. Aims: Within the "hotspot" ejection mechanism, some of the material that is initially transferred from the companion star via an accretion stream is expelled from the system due to the radiative energy released on the gainer's surface by the impacting material. The objective of this paper is to retrieve observable quantities from this process and to compare them with observations. Methods: We investigate the impact of the outflowing gas and the possible presence of dust grains on the spectral energy distribution (SED). We used the 1D plasma code Cloudy and compared the results with the 3D Monte-Carlo radiative transfer code Skirt for dusty simulations. The circumbinary mass-distribution and binary parameters were computed with state-of-the-art binary calculations done with the Binstar evolution code. Results: The outflowing material reduces the continuum flux level of the stellar SED in the optical and UV. Because of the time-dependence of this effect, it may help to distinguish between different ejection mechanisms. If present, dust leads to observable infrared excesses, even with low dust-to-gas ratios, and traces the cold material at large distances from the star. By searching for this dust emission in the WISE catalogue, we found a small number of Algols showing infrared excesses, among which the two rather surprising objects SX Aur and CZ Vel. We find that some binary B[e] stars show the same strong Balmer continuum as we predict with our models. However, direct evidence of systemic mass loss is probably not observable in genuine Algols, since these systems no longer eject mass through the hotspot mechanism. Furthermore, owing to its high velocity, the outflowing material dissipates in a few hundred years. If hot enough, the hotspot may produce highly ionised species, such as Si iv, and observable characteristics that are typical of W Ser systems. Conclusions: If present, systemic mass loss leads to clear observational imprints. These signatures are not to be found in genuine Algols but in the closely related β Lyraes, W Serpentis stars, double periodic variables, symbiotic Algols, and binary B[e] stars. We emphasise the need for further observations of such objects where systemic mass loss is most likely to occur. Appendices are available in electronic form at http://www.aanda.org

Effect of gravitational stratification on the propagation of a CME

NASA Astrophysics Data System (ADS)

Pagano, P.; Mackay, D. H.; Poedts, S.

2013-12-01

Context. Coronal mass ejections (CMEs) are the most violent phenomenon found on the Sun. One model that explains their occurrence is the flux rope ejection model. A magnetic flux rope is ejected from the solar corona and reaches the interplanetary space where it interacts with the pre-existing magnetic fields and plasma. Both gravity and the stratification of the corona affect the early evolution of the flux rope. Aims: Our aim is to study the role of gravitational stratification on the propagation of CMEs. In particular, we assess how it influences the speed and shape of CMEs and under what conditions the flux rope ejection becomes a CME or when it is quenched. Methods: We ran a set of MHD simulations that adopt an eruptive initial magnetic configuration that has already been shown to be suitable for a flux rope ejection. We varied the temperature of the backgroud corona and the intensity of the initial magnetic field to tune the gravitational stratification and the amount of ejected magnetic flux. We used an automatic technique to track the expansion and the propagation of the magnetic flux rope in the MHD simulations. From the analysis of the parameter space, we evaluate the role of gravitational stratification on the CME speed and expansion. Results: Our study shows that gravitational stratification plays a significant role in determining whether the flux rope ejection will turn into a full CME or whether the magnetic flux rope will stop in the corona. The CME speed is affected by the background corona where it travels faster when the corona is colder and when the initial magnetic field is more intense. The fastest CME we reproduce in our parameter space travels at ~850 km s-1. Moreover, the background gravitational stratification plays a role in the side expansion of the CME, and we find that when the background temperature is higher, the resulting shape of the CME is flattened more. Conclusions: Our study shows that although the initiation mechanisms of the CME are purely magnetic, the background coronal plasma plays a key role in the CME propagation, and full MHD models should be applied when one focuses especially on the production of a CME from a flux rope ejection. Movies are available in electronic form at http://www.aanda.org

Periodic cycle of stretching and breaking of the head of gravity currents

NASA Astrophysics Data System (ADS)

Nogueira, H. I. S.; Adduce, C.; Alves, E.; Franca, M. J.

2012-04-01

Gravity currents, which are geophysical flows driven by density differences within a fluid, are herein investigated under unsteady conditions by means of lock-exchange releases of saline water into a fresh water tank. Generally, gravity or density currents are caused by temperature differences or the presence of dissolved substances or particles in suspension. Examples of gravity currents include avalanches of airborne snow and plumes of pyroclasts from volcanic eruptions, in the atmosphere, releases of pollutants and turbidity currents, in rivers, lakes and reservoirs, and oil spillage and oceanic fronts in the ocean. A controlled and convenient fashion to investigate in detail hydrodynamics of unsteady gravity currents is by means of lock-exchange experiments. The propagation of unsteady density currents, produced by lock exchange experiments, present three distinct phases, a first so-called slumping phase when buoyancy and inertial effects are balanced and front celerity is constant, a second (self-similar) phase when the reflected bore from the upper layer ambient fluid upstream drive, caused by continuity within the limited length tank, reaches the current front and causes the front celerity to decrease and provokes a diminution of the current head and, finally, a third viscous phase when viscosity plays a role and its effects overcome inertial effects. On the first and second phase, the current propagation is ruled by buoyancy effects counterbalanced by inertia, Reynolds stresses on the upper mixing layer and bed shear. Buoyancy is reduced due to entrainment and consequently the front velocity, leading to lower Reynolds number flows allowing thus viscosity effects to play a role. As for its anatomy, the current presents two distinct regions, the head and the remaining body or tail. On the very first instants of the release, the flow is bulky driven by the whole current mass while the head is not yet well defined. Later, this detaches from the main body and its particular buoyancy drives the advance of the current, with a different celerity from the tail. The head is highly concentrated being the main engine of convection of the released mass, being subjected to entrainment at the interface with the ambient fluid. The aim of the present work is to experimentally investigate the dynamics of the head, including continuous entrainment and cycles of stretching and breaking observed in the laboratory. Experiments were conducted at the Laboratory of Hydraulics of University of Rome "Roma Tre" in a 3.0 m long, 0.20 m wide and 0.30 m deep transparent Perspex flume. Four lock-exchange release tests were performed varying the density of the saline water. For smooth bed and for a fixed value of water depth, h = 0.20 m, the following four different initial densities of the salt-water mixture were analysed: 1015, 1030, 1045 and 1060 kg/m3. A controlled quantity of dye is added to the saline water in the lock to provide flow visualization and to serve as density tracer. The development of the current is recorded with a 25 Hz CCD camera under controlled light conditions. The resulting video frames are thus converted into grey scale matrices and a calibration procedure establishes a non-linear relation, experimentally determined, between the gray scale values and the quantity of dye in the water. The quantity of dye is converted into salt concentration by assuming a linear relation between quantities, dye and salt, allowing thus the estimation of the 2D instantaneous current density distribution. The experiments allowed the observation of the dynamics of the head of unsteady density currents in detail, including a cyclic increase in dimension and mass due to entrainment followed by a division in two distinct patches. A frontal one continues the drive downstream whereas a subsequent one is left behind and incorporated in the tail, thus indicating that the loss of saline mass in the head is not only due to continuous entrainment at the interface layer. Entrainment follows a decaying trend along the current development whereas periodic division of the head seems to be kept. The division of the head is related to mass ejections directing upstream with a clear signature in the current-depth time and spatial evolution maps. Initial density of the released saline current seems to be related to the period of the cyclic division of the head and the amplitude of the mentioned mass ejections; averaged periods of the occurrence of the divisions are 3.40, 1.63, 1.07 and 0.91 s respectively for initial densities of the salt-water mixture corresponding to 1015, 1030, 1045 and 1060 kg/m3. Research supported by Portuguese Foundation for Science and Technology through the research project PTDC/ECM/099752/2008 and the PhD grant SFRH/BD/48705/2008.

Software Displays Data on Active Regions of the Sun

NASA Technical Reports Server (NTRS)

Golightly, Mike; Weyland, Mark; Raben, Vern

2011-01-01

The Solar Active Region Display System is a computer program that generates, in near real time, a graphical display of parameters indicative of the spatial and temporal variations of activity on the Sun. These parameters include histories and distributions of solar flares, active region growth, coronal mass ejections, size, and magnetic configuration. By presenting solar-activity data in graphical form, this program accelerates, facilitates, and partly automates what had previously been a time-consuming mental process of interpretation of solar-activity data presented in tabular and textual formats. Intended for original use in predicting space weather in order to minimize the exposure of astronauts to ionizing radiation, the program might also be useful on Earth for predicting solar-wind-induced ionospheric effects, electric currents, and potentials that could affect radio-communication systems, navigation systems, pipelines, and long electric-power lines. Raw data for the display are obtained automatically from the Space Environment Center (SEC) of the National Oceanic and Atmospheric Administration (NOAA). Other data must be obtained from the NOAA SEC by verbal communication and entered manually. The Solar Active Region Display System automatically accounts for the latitude dependence of the rate of rotation of the Sun, by use of a mathematical model that is corrected with NOAA SEC active-region position data once every 24 hours. The display includes the date, time, and an image of the Sun in H light overlaid with latitude and longitude coordinate lines, dots that mark locations of active regions identified by NOAA, identifying numbers assigned by NOAA to such regions, and solar-region visual summary (SRVS) indicators associated with some of the active regions. Each SRVS indicator is a small pie chart containing five equal sectors, each of which is color-coded to provide a semiquantitative indication of the degree of hazard posed by one aspect of the activity at the indicated location. The five aspects in question are the history of solar flares, the history of coronal mass ejections, the growth or decay of activity, the overall size, and the magnetic configuration. Mouse-clicking on an active-region-marking dot, SRVS indicator, or NOAA region number causes the program to generate a solar-region summary table (SRT) for the active region in question. The SRT contains additional quantitative and qualitative data, beyond those contained in the SRVS: These data include the solar coordinates of the region, the area of the region and its change in area during the past 24 hours, the change in the number of sunspots in the region during the past 24 hours, the magnetic configuration, and the types, dates, and times of the most recent flare and coronal mass ejection.

Dynamics and Fragmentation of Hydrogen Bonded and van der Waal Clusters upon 26.5 eV Soft X-ray Laser Ionization

NASA Astrophysics Data System (ADS)

Dong, Feng; Heinbuch, Scott; Bernstein, Elliot; Rocca, Jorge

2006-05-01

A desk-top soft x-ray laser is applied to the study of water, methanol, ammonia, sulfur dioxide, carbon dioxide, mixed sulfur dioxide-water, and mixed carbon dioxide-water clusters through single photon ionization time of flight mass spectroscopy. Almost all of the energy above the vertical ionization energy is removed by the ejected electron. Protonated water, methanol, and ammonia clusters dominate the mass spectra for the first three systems. The temperatures of the neutral water and methanol clusters can be estimated. In the case of pure SO2 and CO2, the mass spectra are dominated by (SO2)n^+ and (CO2)n^+ cluster series. When a high or low concentration of SO2/CO2 is mixed with water, we observe (SO2/CO2)nH2O^+ or SO2/CO2(H2O)nH^+ in the mass spectra, respectively. The unimolecular dissociation rate constants for reactions involving loss of one neutral molecule are calculated for the protonated water, methanol, and ammonia clusters as well as for SO2 and CO2 clusters. We find that the 26.5 eV soft x-ray laser is a nearly ideal tool for the study of hydrogen bonded and van der Waals cluster systems and we are currently exploring its usefulness for other more strongly bound systems.

Structural and Functional Phenotyping of the Failing Heart: Is the Left Ventricular Ejection Fraction Obsolete?

PubMed

Bristow, Michael R; Kao, David P; Breathett, Khadijah K; Altman, Natasha L; Gorcsan, John; Gill, Edward A; Lowes, Brian D; Gilbert, Edward M; Quaife, Robert A; Mann, Douglas L

2017-11-01

Diagnosis, prognosis, treatment, and development of new therapies for diseases or syndromes depend on a reliable means of identifying phenotypes associated with distinct predictive probabilities for these various objectives. Left ventricular ejection fraction (LVEF) provides the current basis for combined functional and structural phenotyping in heart failure by classifying patients as those with heart failure with reduced ejection fraction (HFrEF) and those with heart failure with preserved ejection fraction (HFpEF). Recently the utility of LVEF as the major phenotypic determinant of heart failure has been challenged based on its load dependency and measurement variability. We review the history of the development and adoption of LVEF as a critical measurement of LV function and structure and demonstrate that, in chronic heart failure, load dependency is not an important practical issue, and we provide hemodynamic and molecular biomarker evidence that LVEF is superior or equal to more unwieldy methods of identifying phenotypes of ventricular remodeling. We conclude that, because it reliably measures both left ventricular function and structure, LVEF remains the best current method of assessing pathologic remodeling in heart failure in both individual clinical and multicenter group settings. Because of the present and future importance of left ventricular phenotyping in heart failure, LVEF should be measured by using the most accurate technology and methodologic refinements available, and improved characterization methods should continue to be sought. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.