scholarly journals A First Search for Rapid Variations of Stellar and Circumstellar Balmer Discontinuity in Be Stars

1995 ◽  
Vol 155 ◽  
pp. 303-304
Author(s):  
S. Štefl ◽  
D. Baade ◽  
J. Cuypers
Keyword(s):  
High Resolution ◽  
Line Profile ◽  
Time Scale ◽  
Large Amplitude ◽  
High Resolution Spectroscopy ◽  
Be Stars ◽  
Be Star

AbstractSpectrophotometric observations of the Be star ηCen obtained in May, 1993 show smooth variations of both the stellar and circumstellar Balmer discontinuity (BD) on a time scale of hours. Simultaneous photometry and high-resolution spectroscopy suggest possible correlations with the large-amplitude brightness and line-profile variations.

scholarly journals Probing Be star disks: new insights from Hα spectroscopy and detailed numerical models

2010 ◽  
Vol 6 (S272) ◽  
pp. 398-399 ◽  
Author(s):  
Carol E. Jones ◽  
Christopher Tycner ◽  
Jessie Silaj ◽  
Ashly Smith ◽  
T. A. Aaron Sigut
Keyword(s):  
High Resolution ◽  
Numerical Models ◽  
Analytical Tool ◽  
High Resolution Spectroscopy ◽  
Be Stars ◽  
Line Shapes ◽  
Physical Conditions ◽  
Temperature Distributions ◽  
Inclination Angles ◽  
Be Star

AbstractHα high resolution spectroscopy combined with detailed numerical models is used to probe the physical conditions, such as density, temperature, and velocity of Be star disks. Models have been constructed for Be stars over a range in spectral types and inclination angles. We find that a variety of line shapes can be obtained by keeping the inclination fixed and changing density alone. This is due to the fact that our models account for disk temperature distributions self-consistently from the requirement of radiative equilibrium. A new analytical tool, called the variability ratio, was developed to identify emission-line stars at particular stages of variability. It is used in this work to quantify changes in the Hα equivalent widths for our observed spectra.

scholarly journals Line Profile and Photometric Variations of the Be Star η Cen

2002 ◽  
Vol 185 ◽  
pp. 252-253
Author(s):  
R. Levenhagen ◽  
N. Leister ◽  
E. Janot-Pacheco ◽  
J. Zorec ◽  
A. Hubert ◽  
...  
Keyword(s):  
High Resolution ◽  
Line Profile ◽  
Rotational Frequency ◽  
Current Status ◽  
Be Stars ◽  
Rotating Stars ◽  
Fundamental Parameters ◽  
Spectrophotometric Data ◽  
Be Star ◽  
Rapidly Rotating Stars

AbstractWe review the current status of our monitoring project on Be stars. Line profile variations in Helλ667.8 nm were detected in the Be star η Cen, by means of high resolution and S/N Spectroscopic observations. They were interpreted in terms of nonradial pulsations (NRP). The fundamental parameters of η Cen obtained from BCD spectrophotometric data and interpreted using models of rapidly rotating stars, have been used to estimate the stellar rotational frequency.

scholarly journals Hα and NaD Line Variability in RY Tauri

1991 ◽  
Vol 130 ◽  
pp. 471-476
Author(s):  
P. Petrov ◽  
O. Vilhu
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Line Profile ◽  
Stellar Wind ◽  
Time Scale ◽  
Rotational Velocity ◽  
High Resolution Spectroscopy ◽  
Cool Gas ◽  
T Tau ◽  
The Magnetic Field

AbstractUsing high resolution spectroscopy of the T Tau star RY Tau in the regions of Hα and Na D lines, we discovered line profile variability, which is interpreted by a hypothesis of stellar ’prominences’: cool gas clouds are moving inside the stellar wind, ascending and descending on a time scale of a few days. These clouds are supposed to be controlled by the magnetic field of the star. The range of radial velocities of the clouds (−100 to +100 km/s) is twice as large as the rotational velocity (v sin i) of the star. The form of variability of the Hα profile suggests the existence of two components: the (variable) stellar wind and the circumstellar disc.

scholarly journals Simultaneous photometry and spectroscopy of the rapid variability of the Be star η Cen

1994 ◽  
Vol 162 ◽  
pp. 307-308
Author(s):  
S. Štefl ◽  
D. Baade ◽  
P. Harmanec ◽  
L. A. Balona
Keyword(s):  
High Resolution ◽  
Light Curve ◽  
Line Profile ◽  
High Resolution Spectroscopy ◽  
Rapid Variability ◽  
Be Star

The reality of the previously reported triple-wave light curve (Cuypers et al. 1989, A&A Suppl. 81, 151), and relations between rapid line profile and brightness variations of the B1-2III-Ve star η Cen (HD 127972) were investigated by means of simultaneous high-resolution spectroscopy (4 nights, 86 Si III 455.2622 nm profiles) and two-station uvby photometry (14 nights) secured in 1992. To this database were added the uvby photometry by Cuypers et al. and unpublished b observations by L.A.B. from 1988–1991.

scholarly journals TOI-150b and TOI-163b: two transiting hot Jupiters, one eccentric and one inflated, revealed by TESS near and at the edge of the JWST CVZ

2019 ◽  
Vol 490 (1) ◽  
pp. 1094-1110 ◽  
Author(s):  
Diana Kossakowski ◽  
Néstor Espinoza ◽  
Rafael Brahm ◽  
Andrés Jordán ◽  
Thomas Henning ◽  
...  
Keyword(s):  
High Resolution ◽  
Time Scale ◽  
High Resolution Spectroscopy ◽  
Spin Orbit ◽  
Eccentric Orbit ◽  
Hot Jupiters ◽  
Eclipse Observations ◽  
James Webb Space Telescope ◽  
Hot Jupiter

Abstract We present the discovery of TYC9191-519-1b (TOI-150b, TIC 271893367) and HD271181b (TOI-163b, TIC 179317684), two hot Jupiters initially detected using 30-min cadence Transiting Exoplanet Survey Satellite (TESS) photometry from Sector 1 and thoroughly characterized through follow-up photometry (CHAT, Hazelwood, LCO/CTIO, El Sauce, TRAPPIST-S), high-resolution spectroscopy (FEROS, CORALIE), and speckle imaging (Gemini/DSSI), confirming the planetary nature of the two signals. A simultaneous joint fit of photometry and radial velocity using a new fitting package juliet reveals that TOI-150b is a $1.254\pm 0.016\ \rm {R}_ \rm{J}$, massive ($2.61^{+0.19}_{-0.12}\ \rm {M}_ \rm{J}$) hot Jupiter in a 5.857-d orbit, while TOI-163b is an inflated ($R_ \rm{P}$ = $1.478^{+0.022}_{-0.029} \,\mathrm{ R}_ \rm{J}$, $M_ \rm{P}$ = $1.219\pm 0.11 \, \rm{M}_ \rm{J}$) hot Jupiter on a P = 4.231-d orbit; both planets orbit F-type stars. A particularly interesting result is that TOI-150b shows an eccentric orbit ($e=0.262^{+0.045}_{-0.037}$), which is quite uncommon among hot Jupiters. We estimate that this is consistent, however, with the circularization time-scale, which is slightly larger than the age of the system. These two hot Jupiters are both prime candidates for further characterization – in particular, both are excellent candidates for determining spin-orbit alignments via the Rossiter–McLaughlin (RM) effect and for characterizing atmospheric thermal structures using secondary eclipse observations considering they are both located closely to the James Webb Space Telescope (JWST) Continuous Viewing Zone (CVZ).

scholarly journals Recommended isolated-line profile for representing high-resolution spectroscopic transitions (IUPAC Technical Report)

2014 ◽  
Vol 86 (12) ◽  
pp. 1931-1943 ◽  
Author(s):  
Jonathan Tennyson ◽  
Peter F. Bernath ◽  
Alain Campargue ◽  
Attila G. Császár ◽  
Ludovic Daumont ◽  
...  
Keyword(s):  
High Resolution ◽  
Line Profile ◽  
Pressure Effects ◽  
Task Group ◽  
High Resolution Spectroscopy ◽  
Line Shapes ◽  
Neutral Gas ◽  
Voigt Profile ◽  
Simplifying Assumptions ◽  
On Line

Abstract The report of an IUPAC Task Group, formed in 2011 on “Intensities and line shapes in high-resolution spectra of water isotopologues from experiment and theory” (Project No. 2011-022-2-100), on line profiles of isolated high-resolution rotational-vibrational transitions perturbed by neutral gas-phase molecules is presented. The well-documented inadequacies of the Voigt profile (VP), used almost universally by databases and radiative-transfer codes, to represent pressure effects and Doppler broadening in isolated vibrational-rotational and pure rotational transitions of the water molecule have resulted in the development of a variety of alternative line-profile models. These models capture more of the physics of the influence of pressure on line shapes but, in general, at the price of greater complexity. The Task Group recommends that the partially Correlated quadratic-Speed-Dependent Hard-Collision profile (pCqSD-HCP) should be adopted as the appropriate model for high-resolution spectroscopy. For simplicity this should be called the Hartmann–Tran profile (HTP). The HTP is sophisticated enough to capture the various collisional contributions to the isolated line shape, can be computed in a straightforward and rapid manner, and reduces to simpler profiles, including the Voigt profile, under certain simplifying assumptions.

scholarly journals Polarimetry and Physics of Be Star Envelopes (Review paper)

1982 ◽  
Vol 98 ◽  
pp. 77-93 ◽  
Author(s):  
George V. Coyne ◽  
Ian S. McLean
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Theoretical Models ◽  
Geometrical Parameters ◽  
Be Stars ◽  
Intermediate Band ◽  
Wide Range ◽  
Recent Developments ◽  
Be Star ◽  
Polarization Studies

A review of the most recent developments in polarization studies of Be stars is presented. New polarization techniques for high-resolution spectropolarimetry and for near infrared polarimetry are described and a wide range of new observations are discussed. These include broadband, intermediate-band and multichannel observations of the continuum polarization of Be stars in the wavelenght interval 0.3–2.2 microns, high resolution (0.5 Å) line profile polarimetry of a few stars and surveys of many stars for the purposes of statistical analyses. The physical significance of the observational material is discussed in the light of recent theoretical models. Emphasis is placed on the physical and geometrical parameters of Be star envelopes which polarimetry helps to determine.

scholarly journals New Progress in Mode Detection and Identification in δ Scuti Stars by the Analysis of Line Profile Variations

2000 ◽  
Vol 176 ◽  
pp. 463-464
Author(s):  
L. Mantegazza ◽  
E. Poretti ◽  
M. Bossi ◽  
N. S. Nuñez ◽  
A. Sacchi ◽  
...  
Keyword(s):  
High Resolution ◽  
Line Profile ◽  
High Resolution Spectroscopy ◽  
Line Profiles ◽  
Powerful Technique ◽  
Mode Detection ◽  
Detection And Identification ◽  
Scuti Stars ◽  
Δ Scuti Stars ◽  
Nonradial Pulsation

Abstractδ Sct stars are among the most promising targets to perform ground-based asteroseismology. High resolution spectroscopy offers us a powerful technique to identify radial and nonradial pulsation modes, since we can easily detect oscillations and travelling features in the line profiles.

scholarly journals An Unusually Stable and Short Spectroscopic Period of the Be Star 28 CMa

1982 ◽  
Vol 98 ◽  
pp. 167-170
Author(s):  
D. Baade
Keyword(s):  
Time Scale ◽  
Emission Lines ◽  
Be Stars ◽  
Stable Period ◽  
Be Star ◽  
First Time ◽  
Calar Alto

Spectroscopic (1970: ESO, 12 Å/mm, 6 spectra kindly put at my disposal by Prof. A. Van Hoof; 1976: ESO, 12 Å/mm; 1977: Calar Alto Observatory, 42 Å/mm; 1979: ESO, 12 Å/mm) and photometric (1976: ESO and Cerro Tololo, Hβ, uvby) observations of 28 CMa (B2-3 IV-Ve; 3.52 < mV < 4.18, irregular variations on the time scale of months or years reported; vrot = 80 km/s) revealed a very complex variability. All observed individual types of variations are known from at least a few other Be stars. In 28 CMa, however, for the first time a highly significant correlation between the various variations is established by a stable common period. The period is 1.365 days which seems to be the shortest stable period presently known of any Be star. There is no indication that the star's behaviour changed between 1970 and 1979. Only the equivalent widths of the emission lines increased noticeably.

scholarly journals Be Phenomena in Young Early-type Stars: Various Forms of Interaction between the Star and the Circumstellar Gaseous Envelope

2000 ◽  
Vol 175 ◽  
pp. 344-347
Author(s):  
M. Pogodin
Keyword(s):  
High Resolution ◽  
Stellar Wind ◽  
Main Sequence ◽  
Stellar Surface ◽  
High Resolution Spectroscopy ◽  
Evolutionary Status ◽  
Be Stars ◽  
Early Type ◽  
Early Type Stars ◽  
Gaseous Envelope

AbstractNew results of high-resolution spectroscopy of four pre-main sequence Ae/Be stars are presented. An analysis of parameters of lines originating in different regions of the circumstellar (CS) envelope (Hα, Hβ, He I 5876, DNal) allows to reconstruct a picture of the interaction between the star and the CS environment which can be displayed in different forms. At least two separate processes seem to impact the structural and kinematical properties of the envelope: the stellar wind from the stellar surface and the matter infall onto the star from the CS media. A possible relation between these two phenomena is discussed in the framework of different models. Some similarity between observational phenomena in Herbig Ae/Be and classical Be stars is noted in spite of their difference in evolutionary status.

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