scholarly journals HST UV Observations of the Disk and Wind of V795 Her

1996 ◽  
Vol 158 ◽  
pp. 43-44
Author(s):  
S. R. Rosen ◽  
R. K. Prinja ◽  
J. E. Drew ◽  
K. O. Mason ◽  
S. B. Howell
Keyword(s):  
Line Profile ◽  
Emission Feature ◽  
Absorption Feature ◽  
Absorption Component ◽  
Orbital Variation

AbstractHST UV observations of V795 Her reveal a strong 2.6-h orbital variation in the prominent UV lines, in contrast to earlier (IUE) evidence of a 4.8-h period. Only the C IV line contains a strong blue-shifted, wind formed absorption component. Several lines exhibit a ‘narrow’ absorption feature near rest velocity which may originate in the disk, and a blue-shifted emission feature which accounts for most of the line profile variability.

scholarly journals Variability of the Hα Emission in the Be Star o Andromedae

2000 ◽  
Vol 175 ◽  
pp. 543-546
Author(s):  
E. Panko ◽  
A. Tarasov
Keyword(s):  
Line Profile ◽  
Time Interval ◽  
Short Term ◽  
Absorption Component ◽  
Be Star ◽  
Hα Emission

AbstractThe parameters of the Hα line profile of the Be star o And were determined from observations carried out during the period 1985 - 1998. At this time the line has undergone significant changes – from a pure absorption photospheric profile with no sign of an envelope in 1985 to the transition into the shell phase with a very narrow and deep absorption component in 1989. During 1991 - 1998 the Hα emission remained at the level achieved in 1989. The line profile showed short-term changes. The envelope development in the time interval 1985 - 1998 does not confirm the previously found period of 8.5 years.

scholarly journals Line Profile Variability in the Be Star α Eridani

2000 ◽  
Vol 175 ◽  
pp. 272-275 ◽  
Author(s):  
N. V. Leister ◽  
E. Janot-Pacheco ◽  
J. Leyton Z. ◽  
A. M. Hubert ◽  
M. Floquet
Keyword(s):  
Line Profile ◽  
High Velocity ◽  
Absorption Component ◽  
Be Star ◽  
Emission Phase

AbstractWe present an analysis of line profile variability of the Be star α Eri (Achernar). Spectra of He I λ667.8nm were collected at Brazilian Laboratório Nacional de Astrofísica (LNA) during 10 observing runs covering 27 nights in 6 years. The presence of a 1.26 days period reported previously is confirmed and we report also the detection of other periods (0.73 and 0.53 days) and a possible 12.5 days modulation. A transient high-velocity absorption component with RV = −500 km/s, higher than −υsini (−220 km/s) has appeared at the end of 1993, near the presumed maximum of the Hα emission phase.

Mid-IR spectra of the M-type Mira variable R Tri observed with the Spitzer IRS

2020 ◽  
Vol 493 (1) ◽  
pp. 807-814
Author(s):  
Dana K Baylis-Aguirre ◽  
M J Creech-Eakman ◽  
Tina Güth
Keyword(s):  
Ir Spectra ◽  
Emission Feature ◽  
Absorption Feature ◽  
Cool Temperature ◽  
Circumstellar Envelopes ◽  
Mira Variables ◽  
Mira Variable ◽  
Molecular Lines ◽  
Infrared Spectrometer ◽  
Vibrational Bands

ABSTRACT We present analysis of mid-infrared (IR) spectra of the oxygen-rich Mira variable R Tri. The data were taken with the Spitzer Infrared Spectrometer (IRS) as part of a study tracking how Mira variables’ regular pulsations affect circumstellar envelopes. We detected strong emission lines at 13.87, 16.18, and 17.6 $\hbox{$\mu $m}$, and one strong absorption feature at 14.98 $\hbox{$\mu $m}$. The emission features at 13.87 and 16.18 $\hbox{$\mu $m}$ are excited vibrational bands of CO2, while the absorption feature is the fundamental ν2 band. The 17.6 $\hbox{$\mu $m}$ emission feature has a completely different character than the molecular lines and we report its identification as Fe i fluorescence. We used a two-slab model with the radiative transfer code radex to model the CO2 Q-branch bandheads. Our results indicate a slab of gas with T∼600 K located at ∼3–4 R*. The cool temperature discrepancy with the radius provides observational evidence for the previously theoretical ‘refrigeration zone’.

scholarly journals Conditions in the WR 140 wind-collision region revealed by the 1.083-μm He i line profile.

2021 ◽  
Author(s):  
Peredur M Williams ◽  
Watson P Varricatt ◽  
André-Nicolas Chené ◽  
Michael F Corcoran ◽  
Ted R Gull ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Time Scales ◽  
Line Profile ◽  
Absorption Component ◽  
Absorption And Emission ◽  
X Ray ◽  
Collision Region ◽  
Peak Flux ◽  
Orbital Phase ◽  
Phase Range

Abstract We present spectroscopy of the P Cygni profile of the 1.083-μm He i line in the WC7 + O5 colliding-wind binary (CWB) WR 140 (HD 193793), observed in 2008, before its periastron passage in 2009, and in 2016–17, spanning the subsequent periastron passage. Both absorption and emission components showed strong variations. The variation of the absorption component as the O5 star was occulted by the wind-collision region (WCR) sets a tight constraint on its geometry. While the sightline to the O5 star traversed the WCR, the strength and breadth of the absorption component varied significantly on time-scales of days. An emission sub-peak was observed on all our profiles. The variation of its radial velocity with orbital phase was shown to be consistent with formation in the WCR as it swung round the stars in their orbit. Modelling the profile gave a measure of the extent of the sub-peak forming region. In the phase range 0.93–0.99, the flux in the sub-peak increased steadily, approximately inversely proportionally to the stellar separation, indicating that the shocked gas in the WCR where the line was formed was adiabatic. After periastron, the sub-peak flux was anomalously strong and varied rapidly, suggesting formation in clumps down-stream in the WCR. For most of the time, its flux exceeded the 2–10-keV X-ray emission, showing it to be a significant coolant of the shocked wind.

scholarly journals The 8-22μm Excess in Carbon Stars From IRAS LRS Spectra

1989 ◽  
Vol 106 ◽  
pp. 402-402
Author(s):  
S. J. Little ◽  
I. R. Little-Marenin
Keyword(s):  
Dust Emission ◽  
Unknown Origin ◽  
Carbon Star ◽  
Variable Stars ◽  
Emission Feature ◽  
Absorption Feature ◽  
Carbon Stars ◽  
Mira Variables ◽  
Period Variable ◽  
Ir Emission

We have measured the excess IR emission from carbon mira and SR variable stars from IRAS LRS spectra. The 8-22μm excess is defined as the ratio of flux above a 2500K energy distribution fit to the LRS spectrum at about 8μm. The carbon star LRS spectra show both emission and absorption features, which are incorporated into our 8-22pm excess. The most prominent feature in carbon stars is the 11.2μm SiC dust emission feature extending from 10μm to 13.8 μm. We observe another emission feature of unknown origin which peaks between 8.4-8.7μm. The SiC emission feature is occasionally blended on the red side by an absorption feature (attributed to gaseous HCN + C2H2) which extends from about 12-16μm. Many of the spectra appear to turn down at the 8μm end due (?) to an HCN + C2H2 absorption feature located at 7.1μm. Carbon stars do not generally show as large an excess as the M mira variables do. The figure below shows our measured excesses for both carbon miras and carbon semi-regular variables. There appears to be little correlation of excess with period, however the mira variables show about twice the range of variation of excess that the semi-regular variables do. We find little correlation between our measured 8-22μm excess and the excesses of Jura (Ap. J., 303, 327, 1986) based on the ratio of 12μm flux to 2μm flux. Our data do support hi s conclusion that longer period variable stars show larger average excesses, but this is only true for mira variables in our analysis.

scholarly journals Theory of winds from hot stars

1987 ◽  
Vol 122 ◽  
pp. 395-408
Author(s):  
A. G. Hearn
Keyword(s):  
Mass Loss ◽  
Wavelength Range ◽  
Line Profile ◽  
Satellite Observations ◽  
Escape Velocity ◽  
Hot Stars ◽  
Absorption Component ◽  
Loss Of Mass

Mass loss from hot stars was first established by Morton (1967). He observed 3 OB supergiants, δ, ε and ζ Orionis, with an ultraviolet spectrograph sent up with a rocket. In the wavelength range of 1200 A to 2000 A he observed 6 resonance lines of highly ionized atoms such as C III, C IV, N V and Si IV. These resonance lines showed a P Cygni type line profile with an absorption component displaced to the blue corresponding to a velocity away from the stars of 1400 km s−1. Since the escape velocity from these stars is about 800 km s−1 these observations indicated the loss of mass from the stars. With rather simple assumptions he deduced a mass loss from the stars of 1 to 3 10−6 M⊙ yr−1. In spite of many more refined satellite observations and interpretations, the accepted value for mass loss from these stars has not changed by more than a factor of 2 or 3.

Contrast of Filament Bright Rims

1994 ◽  
Vol 144 ◽  
pp. 365-367
Author(s):  
E. V. Kononovich ◽  
O. B. Smirnova ◽  
P. Heinzel ◽  
P. Kotrč
Keyword(s):  
High Altitude ◽  
Line Profile ◽  
Line Center ◽  
Magnetic Structures ◽  
The Mean

AbstractThe Hα filtergrams obtained at Tjan-Shan High Altitude Observatory near Alma-Ata (Moscow University Station) were measured in order to specify the bright rims contrast at different points along the line profile (0.0; ± 0.25; ± 0.5; ± 0.75 and ± 1.0 Å). The mean contrast value in the line center is about 25 percent. The bright rims interpretation as the bases of magnetic structures supporting the filaments is suggested.

Frequency Redistribution Effects in the Formation of Lyman α in Prominences and Their Influence on the Ratio of Hα to Lα

1979 ◽  
Vol 44 ◽  
pp. 53-55
Author(s):  
R.W. Milkey ◽  
J.N. Heasley ◽  
E.J. Schmahl ◽  
O. Engvold
Keyword(s):  
Line Profile ◽  
Large Fraction ◽  
Partial Frequency ◽  
Frequency Redistribution ◽  
Partial Frequency Redistribution ◽  
Emergent Intensity

The effect of partial frequency redistribution in the formation of Lyman α in the chromosphere has been discussed by Milkey and Mihalas (1973) and others, and it has been shown that in this case the coherency of scattering in the wings of the line substantially influences the line profile. Although there are non-negligible sources for La photons within a prominence, a large fraction of the emergent line photons are due to scattering of photons incident on the surface of the prominence so that one expects that in a prominence the frequency redistribution processes will play an important role in determining the emergent intensity.

The Eclipsing Binary WX Eridani

1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar
Keyword(s):  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Primary Component ◽  
Light Curves ◽  
Absorption Feature ◽  
Primary Star ◽  
Eclipsing Binary ◽  
The Times ◽  
Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

Microstructure of post-deformed ECAP-Ti investigated by Multiple X-Ray Line Profile Analysis

2006 ◽  
Vol 2006 (suppl_23_2006) ◽  
pp. 129-134 ◽  
Author(s):  
E. Schafler ◽  
K. Nyilas ◽  
S. Bernstorff ◽  
L. Zeipper ◽  
M. Zehetbauer ◽  
...  
Keyword(s):  
Line Profile ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
X Ray
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