scholarly journals UV Properties of Symbiotic Stars

1983 ◽  
Vol 6 ◽  
pp. 641-642
Author(s):  
M. Kafatos
Keyword(s):  
Accretion Disk ◽  
Binary Systems ◽  
Main Sequence ◽  
Main Sequence Star ◽  
Symbiotic Stars ◽  
International Ultraviolet Explorer ◽  
Type Variable ◽  
Far Ultraviolet

Symbiotic stars are suspected to be binary systems of large dimensions in which one star is a cool primary giant (regular M-giant or Mira-type variable) and the secondary a hot subdwarf (Boyarchuk 1982) or even a main-sequence star with an accretion disk around it (Bath and Pringle 1982). Observations of symbiotic stars in the far ultraviolet with the “International Ultraviolet Explorer” (IUE) enable us to determine the properties of the system in the binary picture. A number of critical observations are needed to do this including an estimate of the photoionizing radiation and the temperature of the photoionizing source.

scholarly journals IUE Ultraviolet Spectra of the Interacting Binary U Cephei

1980 ◽  
Vol 88 ◽  
pp. 237-241
Author(s):  
Yoji Kondo ◽  
George E. McCluskey ◽  
Robert E. Stencel
Keyword(s):  
High Resolution ◽  
Ultraviolet Light ◽  
Stellar Evolution ◽  
Binary Systems ◽  
Light Curves ◽  
Close Binary ◽  
Eclipsing Binary ◽  
Ultraviolet Spectra ◽  
International Ultraviolet Explorer ◽  
Far Ultraviolet

The eclipsing binary U Cephei has proven to be of great interest in the study of stellar evolution in close binary systems. Batten (1974), Hall and Walter (1974), Rhombs and Fix (1976), Markworth (1977), and Olson (1978), among others, have recently reported on their intensive ground based studies of U Cephei. Kondo, McCluskey and Wu (1978) have investigated the ultraviolet light curves of U Cephei obtained with Astronomical Netherlands Satellite (ANS). Kondo, McCluskey and Stencel (1979) have discussed the International Ultraviolet Explorer (IUE) spectra of U Cephei. This paper discusses results incorporating additional IUE high resolution spectra of U Cephei obtained in both far-ultraviolet and mid-ultraviolet spectral regions.

scholarly journals A LOW-MASS MAIN-SEQUENCE STAR AND ACCRETION DISK IN THE VERY FAINT X-RAY TRANSIENT M15 X-3

2015 ◽  
Vol 807 (1) ◽  
pp. 52 ◽  
Author(s):  
R. M. Arnason ◽  
G. R. Sivakoff ◽  
C. O. Heinke ◽  
H. N. Cohn ◽  
P. M. Lugger
Keyword(s):  
Accretion Disk ◽  
Main Sequence ◽  
Main Sequence Star ◽  
X Ray ◽  
Low Mass

scholarly journals V2282 Sgr Revisited

2014 ◽  
Vol 1 (1) ◽  
pp. 118-122
Author(s):  
Roberto Nesci ◽  
Corinne Rossi ◽  
Antonio Frasca ◽  
Ettore Marilli ◽  
Paolo Persi ◽  
...  
Keyword(s):  
Light Curve ◽  
Accretion Disk ◽  
Main Sequence ◽  
Optical Spectra ◽  
Emission Lines ◽  
Main Sequence Star ◽  
Strong Emission ◽  
X Ray ◽  
Type Spectrum

The nature of V2282 Sgr is examined on the basis of several multiband observations: a 20 years long I-band light curve of V2282 Sgr obtained from archive photographic plates of the Asiago and Catania Observatories; a CCD R-band light curve obtained at Cornero Observatory; JHK photometry from 2MASS and UKDISS; <em>Spitzer</em> IRAC and MIPS images; optical spectra from Loiano Observatory; X-ray flux from <em>CHANDRA</em>. The star has a K-type spectrum with strong emission lines and is irregularly variable at all wavebands. The overall evidences suggest that V2282 Sgr is a Pre Main Sequence star with an accretion disk.

scholarly journals Compact object detection in self-lensing binary systems with a main-sequence star

2010 ◽  
Vol 410 (2) ◽  
pp. 912-918 ◽  
Author(s):  
S. Rahvar ◽  
A. Mehrabi ◽  
M. Dominik
Keyword(s):  
Object Detection ◽  
Binary Systems ◽  
Main Sequence ◽  
Compact Object ◽  
Main Sequence Star

scholarly journals Ultraviolet Spectroscopic Measurements of Cool Stars

1980 ◽  
Vol 5 ◽  
pp. 263-276 ◽  
Author(s):  
A. K. Dupree
Keyword(s):  
Binary Systems ◽  
Stellar Atmospheres ◽  
Late Type ◽  
Near Ultraviolet ◽  
International Ultraviolet Explorer ◽  
Cool Stars ◽  
Late Type Star ◽  
Far Ultraviolet ◽  
Low Dispersion ◽  
Balloon Measurements

A vast increase in the amount of information on cool stars has occurred during the past 3 years starting with the spectroscopy of the brightest objects from the Princeton experiment on Copernicus, the near ultraviolet balloon measurements from BUSS, low dispersion observations in the far ultraviolet from rocket instruments, and most recently, spectra from the International Ultraviolet Explorer satellite (IUE). IUE now gives access to a wide variety of cool stars and stellar systems enabling systematic studies to be made.Drawing on the most recent material from IUE, we discuss the presence and structure of chromospheres and coronae in single stars of varying gravities, surface temperatures, and activity. Evidence of mass loss and the concurrent presence of a corona are also noted. Binary systems of late-type stars (the RS CVn and W UMa type) are briefly discussed since they display extremes of surface activity. A binary system such as VV Cep containing a late-type star and an early-type companion provides a unique probe of cool extended stellar atmospheres.

scholarly journals Some Photometric Peculiarities of Symbiotic Stars

1975 ◽  
Vol 67 ◽  
pp. 395-395
Author(s):  
T. S. Belyakina
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Light Curves ◽  
Symbiotic Stars ◽  
Ceti Type ◽  
Photoelectric Observations ◽  
The Right

The results of UBV photoelectric observations of 12 symbiotic stars have been considered. It must be noted that their light-curves are very different (irregular, regular, of Mira Ceti type) and, in the two-colour diagram (B – V)–(U – B), all these stars are located rather far to the right from the main sequence. The photometric peculiarities of symbiotic stars just mentioned can be explained by assuming that they are binary systems.

scholarly journals An Unsuccessful Search for White Dwarf Companions to Nearby Main Sequence Stars

1989 ◽  
Vol 114 ◽  
pp. 134-137
Author(s):  
Harry L. Shipman ◽  
Jeanne Geczi
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Binary Systems ◽  
Main Sequence ◽  
Main Sequence Star ◽  
Main Sequence Stars ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
M Stars

AbstractMany of the nearest white dwarf stars (e.g., Sirius B and Procyon B) are in such binaries and would have remained undiscovered if they were even a little bit further away. White dwarfs which are sufficiently hot (T(eff) > 10,000 K) would, if present in binary systems with a relatively cool (F, G, K, or M) main–sequence secondary, be visible in IUE images as a hot companion to the main sequence star. We systematically examined 318 IUE images of 280 different G, K, and M stars which had been observed for other purposes. No previously undiscovered white dwarf stars were found.

A large rotating structure around AB Doradus A at VLBI scale

2019 ◽  
Vol 15 (S354) ◽  
pp. 189-194
Author(s):  
J. B. Climent ◽  
J. C. Guirado ◽  
R. Azulay ◽  
J. M. Marcaide
Keyword(s):  
Magnetic Reconnection ◽  
Main Sequence ◽  
Complex Structure ◽  
Main Sequence Star ◽  
Polar Cap ◽  
Vlbi Observations ◽  
Rotating Structure ◽  
Source Structure ◽  
Expected Position

AbstractWe report the results of three VLBI observations of the pre-main-sequence star AB Doradus A at 8.4 GHz. With almost three years between consecutive observations, we found a complex structure at the expected position of this star for all epochs. Maps at epochs 2007 and 2010 show a double core-halo morphology while the 2013 map reveals three emission peaks with separations between 5 and 18 stellar radii. Furthermore, all maps show a clear variation of the source structure within the observing time. We consider a number of hypothesis in order to explain such observations, mainly: magnetic reconnection in loops on the polar cap, a more general loop scenario and a close companion to AB Dor A.

Subaru Hyper Suprime-Cam Survey for the Local Group Dwarf Galaxies: Ursa Minor

2018 ◽  
Vol 14 (S344) ◽  
pp. 94-95
Author(s):  
Yutaka Komiyama
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Structural Parameters ◽  
Deep Imaging ◽  
Ursa Minor ◽  
Red Giant

AbstractWe have carried out a wide and deep imaging survey for the Local Group dwarf spheroidal galaxy Ursa Minor (UMi) using Hyper Suprime-Cam (HSC). The data cover out beyond the nominal tidal radius down to ~25 mag in i band, which is ~2 mag below the main sequence turn-off point. The structural parameters of UMi are derived using red giant branch (RGB) stars and sub-giant branch (SGB) stars, and the tidal radius is suggested to be larger than those estimated by the previous studies. It is also found that the distribution of bluer RGB/SGB stars is more extended than that of redder RGB/SGB stars. The fraction of binary systems is estimated to be ~0.4 from the morphology of the main sequences.

scholarly journals Variable, Optically Thick, Hot Plasma Observed in Interacting Binaries

1984 ◽  
Vol 80 ◽  
pp. 281-286
Author(s):  
Y. Kondo ◽  
G. E. McCluskey ◽  
S. B. Parsons
Keyword(s):  
Binary Systems ◽  
Ultraviolet Spectra ◽  
Hot Plasma ◽  
International Ultraviolet Explorer

AbstractWe report recent International Ultraviolet Explorer (IUE) observations of two interacting binaries, R Arae and HD 207739. The ultraviolet spectra indicate the presence of optically-thick, variable hot plasma in those binary systems. These two binaries may belong to a class of binaries that are currently undergoing a rarely observed and probably short-lived phase in their evolution. Their properties are compared with those of two other interacting binaries, U Cephei and ß Lyrae.

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