scholarly journals X Sources in δ Scuti Stars: an Ultraviolet Study of 71 Tau

1993 ◽  
Vol 139 ◽  
pp. 396-396
Author(s):  
L.E. Pasinetti Fracassini ◽  
L. Pastori ◽  
F. De Nile ◽  
E. Poretti ◽  
E. Antonello
Keyword(s):  
Mass Loss ◽  
Spectroscopic Data ◽  
Pulsation Period ◽  
X Ray ◽  
Chromospheric Activity ◽  
Hyades Cluster ◽  
Photometric Observations ◽  
Scuti Stars ◽  
Einstein Observatory ◽  
Δ Scuti Stars

IUE observations of δ Scuti variables were planned to study the correlations between chromospheric activity and dynamics of pulsations, convection, rotation and to search for evidence of mass loss. So far we observed the following stars: ρ Pup, β Cas, o1 Eri, K2 Boo, τ Peg, 69 Tau, 71 Tau and τ Cyg. Results and discussions on our survey may be found in Pasinetti Fracassini et al. (1990) and Fracassini et al. (1991).Ultraviolet spectroscopic data (6 LWP and 3 SWP spectra) of 71 Tau were obtained with IUE in the year 1990, spanning an interval of 5h35rn and covering about 1.5 cycles of the pulsation period. The period, derived from new photometric observations, is 4h32m with an cimplitude of 0m.028. This variable is the most intense X-ray source in the Hyades cluster according to the results of Einstein Observatory.

scholarly journals Spectroscopy of southern δ Scuti stars

2004 ◽  
Vol 193 ◽  
pp. 275-278
Author(s):  
Malcolm Cropp ◽  
Karen R. Pollard ◽  
Jovan Skuljan
Keyword(s):  
New Zealand ◽  
Spectral Line ◽  
Radial Velocity ◽  
Spectroscopic Data ◽  
Cross Correlation ◽  
Correlation Technique ◽  
Echelle Spectrograph ◽  
Cross Correlation Technique ◽  
Scuti Stars ◽  
Δ Scuti Stars

AbstractFour δ Scuti stars were observed with the HERCULES fibrefed échelle spectrograph at Mount John University Observatory, New Zealand. These observations were analysed by looking at the radial velocity variations as given by a cross-correlation technique as well as spectral line moment variations. These results were compared to published photometric studies of these stars to see if the modes identified in the photometry were also present in the spectroscopic data obtained.

scholarly journals Non-Equilibrium Ionization in Puppis A

1983 ◽  
Vol 101 ◽  
pp. 245-252
Author(s):  
P. F. Winkler ◽  
C. R. Canizares ◽  
B. C. Bromley
Keyword(s):  
High Resolution ◽  
Spectroscopic Data ◽  
Supernova Remnant ◽  
Optical Data ◽  
Equilibrium Conditions ◽  
X Ray ◽  
Flux Measurements ◽  
Far From Equilibrium ◽  
Einstein Observatory ◽  
Non Equilibrium

High resolution X-ray spectroscopy of the brightest knot of emission in the Puppis A supernova remnant shows that it is made up of ionizing plasma, far from equilibrium. Flux measurements in several X-ray lines enable us to determine the non-equilibrium conditions: electron temperature, ion populations, and time since the knot was heated by the supernova shock. Imaging and spectroscopic data from the Einstein Observatory together suggest that this knot is a cloud of density about 10 cm−3 which has recently been shocked to a temperature 7 × 106 K. Radio and optical data on the region appear consistent with this picture.

Study of Pulsations in the Nova-like Variable KR Aur and the Intermediate Polar BG CMi

1991 ◽  
Vol 9 (2) ◽  
pp. 279-280
Author(s):  
J. Singh ◽  
P. C. Agrawal ◽  
M. V. K. Apparao ◽  
R. K. Manchanda ◽  
P. Vivekananda Rao ◽  
...  
Keyword(s):  
Neutron Star ◽  
White Dwarf ◽  
Accretion Disc ◽  
Light Curves ◽  
Pulsation Period ◽  
Variable Amplitude ◽  
X Ray ◽  
Photometric Observations ◽  
The Times ◽  
Made In

AbstractFast photometric observations of a nova-like variable KR Aurigae and the intermediate polar BG CMi (3A0729+103) were made in the B and U bands during 1984–89 to study pulsations in them. The light curves of KR Aur show large amplitude quasi-periodic pulsations with periods in the range 500–800s which can be ascribed to inhomogeneities in the accretion disc. The light curves of the X-ray emitting intermediate polar BG CMi show variable amplitude pulsations with 913s period. From the times of maxima of the pulsations obtained from observations over the period 1984–1989, the pulsation period is derived to be 0.010572966 ± 8 days and the spin-up rate to be (−5.7 ± 0.5) × 10−11 ss−1. The spin-up rate is consistent with the pulsating source being a white dwarf and not a neutron star.

scholarly journals Discovery of FK comae and RS CVn systems by observation of their X-ray emission

1987 ◽  
Vol 122 ◽  
pp. 367-367
Author(s):  
Thomas A. Fleming ◽  
Isabella Gioia ◽  
Tommaso Maccacaro
Keyword(s):  
Optical Spectroscopy ◽  
Binary Systems ◽  
Cataclysmic Variables ◽  
Radial Velocities ◽  
Surface Gravity ◽  
X Ray ◽  
Chromospheric Activity ◽  
Flare Stars ◽  
Einstein Observatory ◽  
Temperature Surface

We are currently working with a statistically complete, unbiased sample of 125 x-ray-bright stars which were serendipitously detected by the Einstein Observatory Medium Sensitivity Survey (MSS). A program of optical spectroscopy and photometry is currently underway to measure radial velocities, distances, and such stellar parameters as rotation, temperature, surface gravity, metallicity, chromospheric activity, and age and to correlate them with absolute x-ray luminosity. So far, the majority of the sample (which was defined at |bII| > 20o) appears to be composed of either flare stars (e.g. dMe, dKe) or active binary systems (e.g. cataclysmic variables, RS CVn, W UMa).

scholarly journals Asteroseismic Analysis of δ Scuti Components of Binary Systems: The Case of KIC 8504570

Galaxies ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 75
Author(s):  
Alexios Liakos ◽  
Panagiotis Niarchos
Keyword(s):  
Light Curve ◽  
Binary Systems ◽  
Theoretical Models ◽  
Primary Component ◽  
Physical Parameters ◽  
Pulsation Period ◽  
Oscillation Modes ◽  
Scuti Star ◽  
Scuti Stars ◽  
Δ Scuti Stars

The present work concerns the Asteroseismology of the Kepler-detached eclipsing binary KIC 8504570. Particularly, it focuses on the pulsational behaviour of the oscillating component of this system and the estimation of its physical parameters in order to enrich the so far poor sample of systems of this kind. Using spectroscopic observations, the spectral type of the primary component was determined and used to create accurate light curve models and estimate its absolute parameters. The light curve residuals were subsequently analysed using Fourier transformation techniques to obtain the pulsation models. Theoretical models of δ Scuti stars were employed to identify the oscillation modes of the six detected independent frequencies of the pulsator. In addition, more than 385 combination frequencies were also detected. The absolute and the pulsational properties of the δ Scuti star of this system are discussed and compared with all the currently known similar cases. Moreover, using a recent(empirical) luminosity–pulsation period relationship for δ Scuti stars, the distance of the system was estimated.

scholarly journals Nonadiabatic observables in main sequence δ Scuti stars

2004 ◽  
Vol 193 ◽  
pp. 271-274
Author(s):  
A. Moya ◽  
R. Garrido ◽  
M.-A. Dupret
Keyword(s):  
Mixing Length ◽  
Mode Identification ◽  
Photometric Observations ◽  
Pulsation Model ◽  
Atmosphere Interaction ◽  
Mixing Length Theory ◽  
Scuti Stars ◽  
Δ Scuti Stars ◽  
Model Phase ◽  
Phase Differences

AbstractUsing a theoretical nonadiabatic pulsation model, phase differences and amplitude ratios between the relative effective temperature variation and the relative radial displacement have been calculated. These quantities, when compared with photometric observations in different colours, provide an efficient instrument for mode identification, the first step to understand the internal structure of the stars. The theoretical results presented in this paper show a dependence for δ Scuti stars on the mixing length parameter α used to treat the convection using the standard Mixing Length Theory. The nonadiabatic pulsational code developed here includes the pulsation-atmosphere interaction as described by Dupret et al. (2002). The equilibrium models are provided by the CESAM evolutionary code, where a complete reconstruction of non-grey atmospheres (Kurucz models) is included.

scholarly journals Infrared observations and mass loss of the binary system V861 Sco

1981 ◽  
Vol 59 ◽  
pp. 477-480 ◽  
Author(s):  
E.G. Tanzi ◽  
L. Maraschi ◽  
M. Tarenghi ◽  
A. Treves
Keyword(s):  
Binary System ◽  
Mass Loss ◽  
Mass Flow ◽  
Secondary Component ◽  
Single Line ◽  
Infrared Excess ◽  
Infrared Observations ◽  
X Ray ◽  
Photometric Observations ◽  
Ultraviolet Observations

V 861 Sco (HD 152667) is a well known single line binary(1,2).The proposed association with a variable X-ray source(3,4) has triggered renewed interest in the system. Recent optical, infrared and ultraviolet observations(5 - 12) have provided a better knowledge of its characteristics. A first estimate of the mass loss was given by Hutchings(13).Here we report on a series of photometric observations in the infrared (from 1.25 to 4.8 µ) taken at various orbital phases which improve and extend previous measurements by Tanzi et al.(12)The results give evidence of a phase modulated infrared excess which can be interpreted in terms of a non isotropic mass flow in the system or, alternately, of a contribution from a colder secondary component.

scholarly journals Stellar X-Ray Activity in the Hyades

1983 ◽  
Vol 71 ◽  
pp. 131-134
Author(s):  
Robert A. Stern ◽  
Marie-Christine Zolcinski
Keyword(s):  
Binary System ◽  
Transition Region ◽  
X Ray ◽  
Spectroscopic Binary ◽  
Hyades Cluster ◽  
Solar Type ◽  
High Level ◽  
Einstein Observatory ◽  
Region Line

Observations of the Hyades cluster with the Einstein Observatory and with IUE have uncovered a high level of coronal x-ray emission (Lx≃1029 era s-1 for solar-type stars) and similarly high fluxes of chromospheric and transition region line fluxes compared to the gun (Stern et al.1981, Zolcinski et al. 1981, 1982). A giant x-ray flare from a spectroscopic binary system in the Hyades has also been reported (Stern, Antiochos and Underwood 1982).

scholarly journals The Pulsation Period and Possible Orbit of 1E2259+586

1983 ◽  
Vol 101 ◽  
pp. 445-453
Author(s):  
G. G. Fahlman ◽  
P. C. Gregory
Keyword(s):  
Light Curve ◽  
Orbital Motion ◽  
Pulsation Period ◽  
Pulse Period ◽  
Arrival Times ◽  
X Ray ◽  
Einstein Observatory

The currently known characteristics of the unique x-ray pulsar 1E2259+586 are briefly reviewed. The results from a recently completed analysis of the x-ray photon arrival times recorded by the Einstein Observatory are presented. The pulsar light curve has changed shape between two epochs separated by six months. The true pulse period is 6.978632 sec, double the previously reported value. In addition, there is evidence for orbital motion with a period close to 2300 sec. Some implications of this orbit are briefly discussed.

Electron Beam-Induced Mass Loss in Freeze-Dried Tissue and Protein Samples

1985 ◽  
Vol 43 ◽  
pp. 470-471
Author(s):  
M.E. Cantino ◽  
M.K. Goddard ◽  
L.E. Wilkinson ◽  
D.E. Johnson
Keyword(s):  
Electron Beam ◽  
Salivary Gland ◽  
Mass Loss ◽  
Counting Rate ◽  
Dose Dependence ◽  
X Ray ◽  
Large Samples ◽  
Freeze Dried ◽  
Muscle Homogenate ◽  
Large Muscle

Quantification in biological x-ray microanalysis depends on accurate evaluation of mass loss. Although several studies have addressed the problem of electron beam induced mass loss from organic samples (eg., 1,2). uncertainty persists as to the dose dependence, the extent of loss, the elemental constituents affected, and the variation in loss for different materials and tissues. in the work described here, we used x-ray counting rate changes to measure mass loss in albumin (used as a quantification standard), salivary gland, and muscle.In order to measure mass loss at low doses (10-4 coul/cm2 ) large samples were needed. While freeze-dried salivary gland sections of the required dimensions were available, muscle sections of this size were difficult to obtain. To simulate large muscle sections, frog or rat muscle homogenate was injected between formvar films which were then stretched over slot grids and freeze-dried. Albumin samples were prepared by a similar procedure. using a solution of bovine serum albumin in water. Samples were irradiated in the STEM mode of a JEOL 100C.

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