scholarly journals Ultraviolet Variability of the Symbiotic Star AG PEG

1988 ◽  
Vol 103 ◽  
pp. 263-264
Author(s):  
D. Chochol ◽  
Z. Komárek ◽  
A. Vittone
Keyword(s):  
Optical Spectra ◽  
Radial Velocities ◽  
Roche Lobe ◽  
Emission Lines ◽  
High Dispersion ◽  
Symbiotic Star ◽  
Observational Material

Symbiotic star AG Peg consists of a hot subdwarf with a WN6 spectrum and a cool M3 giant, which is not filling its Roche lobe (Boyarchuk 1967, 1985). A detailed study of profiles, equivalent widths and radial velocities of emission lines in optical spectra allowed Hutchings et al. (1975) to conclude that a hot subluminous star approximately 1 M⊙ rotates rapidly and ejects material which streams towards the cool M giant with the mass 3-4 M⊙. UV observations seems to support this model.UV observations provided from the databank of the IUE satellite were obtained in 1978–81 by different observers. The observational material consists of 12 high dispersion SWP spectra and covers the region 1200 – 2100 A. The spectra were reduced at Trieste observatory using standard IUESIPS package. The radial velocities of emission lines were measured on tracings and corrected for the motion of Earth and satellite.

scholarly journals Ultraviolet Variability of AX Persei

1988 ◽  
Vol 103 ◽  
pp. 303-304
Author(s):  
Joanna Mikolajewska
Keyword(s):  
Optical Spectra ◽  
Radial Velocities ◽  
Roche Lobe ◽  
Emission Lines ◽  
Eclipsing Binary ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations ◽  
Red Giant

Recent photometric and spectroscopic observations suggest AX Per might be an eclipsing binary with a period of about 682 days (Kenyon 1986 and references therein). The analysis of optical spectra taken during 1979-1986 has shown periodic minima in all observed permitted lines and a lack of any periodicity in the forbidden lines (Mikolajewska 1987; Mikolajewska & lijima 1987). A comparison of the available radial velocities with these intensity variations shows that the behaviour of emission lines is consistent with the eclipse interpretation, however the minima (especially in HI and HeI) are too broad to be consistent with eclipses even by a Roche lobe filling red giant. In the following, the UV behaviour of AX Per is analysed using IUE spectra collected during the period 1979-1984.

scholarly journals High Luminosity F-K Stars Motions and Hα Emissions

1980 ◽  
Vol 51 ◽  
pp. 170-170
Author(s):  
J. Smolinski ◽  
J.L. Climenhaga ◽  
B.L. Harris
Keyword(s):  
Radial Velocity ◽  
Radial Velocities ◽  
Emission Lines ◽  
High Dispersion ◽  
Common Phenomenon ◽  
Line Profiles ◽  
High Luminosity ◽  
Regular Time ◽  
Time Variations

AbstractChanges and differences in radial velocities between neutral and ionized metals have been found for three F5-type supergiants: HD 231195, HD 10494, and HD 17971. Fifteen high dispersion coudé spectrograms (6 Å/mm) were used and 33 to 165 lines were measured on each. Semi-regular time variations up to about 8 km s-1 in radial velocity have been found. In addition, Hα line profiles for 8 high luminosity F-K stars have been analyzed. All of the stars show Ha emissions, variable in time, which is probably a common phenomenon in very luminous stars. Metallic emission lines with low excitation potentials, in particular the Ca I 6572.8 and the Fe I 6574.2 lines, are present in 5 of these stars.

scholarly journals Periodic Variations in the Symbiotic Star Spectra

1987 ◽  
Vol 93 ◽  
pp. 713-723 ◽  
Author(s):  
J. Mikolajewska
Keyword(s):  
Emission Line ◽  
Radial Velocities ◽  
Emission Lines ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Line Intensities ◽  
Physical Conditions

AbstractPeriodic variations of emission line intensities and radial velocities in three S-type symbiotic stars: BF Cyg, CI Cyg and AX Per are presented and discussed. The behavior of emission lines is different in these objects and suggests that significant differences in physical conditions and geometry may occur in these seemingly similar systems.

scholarly journals Southern emission line flux standards

1997 ◽  
Vol 180 ◽  
pp. 20-20
Author(s):  
M. A. Dopita ◽  
C. T. Hua
Keyword(s):  
Emission Line ◽  
Supplement Series ◽  
Radial Velocities ◽  
Emission Lines ◽  
High Dispersion ◽  
Line Flux ◽  
Astrophysical Journal ◽  
Line Imaging

Absolute emission line imaging photometry is often made difficult by the absence of good flux standards. Even bright PN often show as much as 25between different authors, reflecting the varying techniques of observation. In order to correct this situation, we have made slitless absolute spectrophotometric observations at high dispersion of compact (!5 arc sec. diameter) PN drawn from the Acker al. (1992) Catalogue. The complete results will appear in the Astrophysical Journal Supplement Series in early 1997. This paper gives absolute Hα, Hβ line fluxes, equivalent widths, accurate radial velocities, and relative fluxes of a number of other emission lines for some 50 PN in the southern sky between 7hr and 17hr in R.A.

Spectroscopic Monotoring of the Symbiotic Star BX Monocerotis

2012 ◽  
Vol 21 (1-2) ◽  
Author(s):  
G. C. Anupama ◽  
U. S. Kamath ◽  
U. K. Gurugubelli ◽  
J. Mikołajewska
Keyword(s):  
Optical Spectra ◽  
Emission Lines ◽  
Symbiotic Star ◽  
Low Resolution ◽  
Cool Component

AbstractLow resolution optical spectra of the symbiotic star BX Monocerotis in the 3500-9000 Å range obtained during 1999–2010 are described. the spectrum of BX Mon at all phases is dominated by the cool component, with a red continuum and TiO absorption. Emission lines, predominantly due to HI, He I, He II, Fe II, Ca II and [O III] are seen superimposed on the spectrum of the M5III star, with variable intensities. the observed variations in the spectra seem to be correlated with the orbital phases.

scholarly journals YZ Cas ± 0.5%

1983 ◽  
Vol 62 ◽  
pp. 108-113
Author(s):  
Claud H. Lacy
Keyword(s):  
Solid State ◽  
Signal To Noise Ratio ◽  
Radial Velocities ◽  
Eclipsing Binaries ◽  
Emission Lines ◽  
Array Detector ◽  
High Dispersion ◽  
Signal To Noise ◽  
Noise Ratio ◽  
M Dwarf

I will discuss one of the results of a continuing program to determine accurate masses and radii of stars in eclipsing binaries. This program actually began in 1976 with my work on the faint M-dwarf system CM Dra (Lacy 1977). By faint I mean . I needed high-dispersion spectra to get radial velocities, and an intensified solid state array detector called the Digicon, which had recently been installed on the coude spectrometer of the 2.7m reflector at McDonald Observatory, turned out to be the answer. 30 minute integrations were sufficient to get accurate radial velocities from the Hγ emission lines. The Digicon is very good at getting crumby spectra of faint objects fast. By crumby, I mean signal-to-noise ratio of less than 100.

Discovery of five new Galactic symbiotic stars in the VPHAS+ survey

2021 ◽  
Vol 502 (2) ◽  
pp. 2513-2517
Author(s):  
Stavros Akras ◽  
Denise R Gonçalves ◽  
Alvaro Alvarez-Candal ◽  
Claudio B Pereira
Keyword(s):  
Spectroscopic Data ◽  
Selection Criterion ◽  
Optical Spectra ◽  
Emission Lines ◽  
High Rate ◽  
Symbiotic Stars ◽  
Selection Of

ABSTRACT We report the validation of a recently proposed infrared (IR) selection criterion for symbiotic stars (SySts). Spectroscopic data were obtained for seven candidates, selected from the SySt candidates of Akras et al. by employing the new supplementary IR selection criterion for SySts in the VST/OmegaCAM Photometric H-Alpha Survey. Five of them turned out to be genuine SySts after the detection of H α, He ii, and [O iii] emission lines as well as TiO molecular bands. The characteristic O vi Raman-scattered line is also detected in one of these SySts. According to their IR colours and optical spectra, all five newly discovered SySts are classified as S-type. The high rate of true SySts detections of this work demonstrates that the combination of the H α emission and the new IR criterion improves the selection of target lists for follow-up observations by minimizing the number of contaminants and optimizing the observing time.

scholarly journals X-ray variability of the HMXB Cen X-3: evidence for inhomogeneous accretion flows.

2020 ◽  
Author(s):  
G Sanjurjo-Ferrín ◽  
J M Torrejón ◽  
K Postnov ◽  
L Oskinova ◽  
J J Rodes-Roca ◽  
...  
Keyword(s):  
Equivalent Width ◽  
Compact Star ◽  
Timing Analysis ◽  
Roche Lobe ◽  
The Other ◽  
Emission Lines ◽  
High Mass ◽  
X Ray ◽  
Accretion Flows ◽  
Inner Radius

Abstract Cen X-3 is a compact high mass X-ray binary likely powered by Roche lobe overflow. We present a phase-resolved X-ray spectral and timing analysis of two pointed XMM-Newton observations. The first one took place during a normal state of the source, when it has a luminosity LX ∼ 1036 erg s−1. This observation covered orbital phases φ = 0.00 − 0.37, i.e. the egress from the eclipse. The egress lightcurve is highly structured, showing distinctive intervals. We argue that different intervals correspond to the emergence of different emitting structures. The lightcurve analysis enables us to estimate the size of such structures around the compact star, the most conspicuous of which has a size ∼0.3R*, of the order of the Roche lobe radius. During the egress, the equivalent width of Fe emission lines, from highly ionized species, decreases as the X-ray continuum grows. On the other hand, the equivalent width of the Fe Kα line, from near neutral Fe, strengthens. This line is likely formed due to the X-ray illumination of the accretion stream. The second observation was taken when the source was 10 times X-ray brighter and covered the orbital phases φ = 0.36 − 0.80. The X-ray lightcurve in the high state shows dips. These dips are not caused by absorption but can be due to instabilities in the accretion stream. The typical dip duration, of about 1000 s, is much longer than the timescale attributed to the accretion of the clumpy stellar wind of the massive donor star, but is similar to the viscous timescale at the inner radius of the accretion disk.

scholarly journals Nebular and auroral emission lines of [Cl III] in the optical spectra of planetary nebulae

2000 ◽  
Vol 97 (9) ◽  
pp. 4551-4555 ◽  
Author(s):  
F. P. Keenan ◽  
L. H. Aller ◽  
C. A. Ramsbottom ◽  
K. L. Bell ◽  
F. L. Crawford ◽  
...  
Keyword(s):  
Planetary Nebulae ◽  
Optical Spectra ◽  
Emission Lines ◽  
Auroral Emission

scholarly journals Recent studies of the spectrum of V1016 Cygni

1982 ◽  
Vol 70 ◽  
pp. 161-164
Author(s):  
G. Muratorio ◽  
M. Friedjung
Keyword(s):  
Radial Velocity ◽  
Ionization Potential ◽  
Radial Velocities ◽  
Emission Lines ◽  
Computer Programme ◽  
Half Maximum ◽  
The Mean ◽  
Effective Ionization

Two coudé spectra of V1016 Cyg taken on June 24 and 27, 1979 were reduced, using a computer programme developed in Marseille. Radial velocities and full widths at half maximum were measured for the emission lines, and are summarized in the following table were VR is the mean radial velocity in km s-1, DV the velocity corresponding to the mean FWHM and Xi the effective ionization potential for the ion.

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