J/AJ/145/95 Spectroscopy of ε Ori (Thompson+, 2013)
Variability in optical spectra of ε Orionis.
Thompson G.B., Morrison N.D.
<Astron. J., 145, 95 (2013)>
=2013AJ....145...95T 2013AJ....145...95T
ADC_Keywords: Equivalent widths ; Radial velocities ; Stars, early-type ;
Stars, variable
Keywords: line: profiles - stars: early-type - stars: winds, outflows -
stars: individual (* eps Ori,HD 37128) - stars: mass-loss
Abstract:
We present the results of a time series analysis of 130 echelle
spectra of ε Ori (B0 Ia), acquired over seven observing
seasons between 1998 and 2006 at Ritter Observatory. The equivalent
widths of Hα (net) and HeIλ5876 were measured and radial
velocities were obtained from the central absorption of
HeIλ5876. Temporal variance spectra (TVS) revealed significant
wind variability in both Hα and HeIλ5876. The HeI TVS
have a double-peaked profile consistent with radial velocity
oscillations. A periodicity search was carried out on the equivalent
width and radial velocity data, as well as on wavelength-binned
spectra. This analysis has revealed several periods in the variability
with timescales of two to seven days. Many of these periods exhibit
sinusoidal modulation in the associated phase diagrams. Several of
these periods were present in both Hα and HeI, indicating a
possible connection between the wind and the photosphere. Due to the
harmonic nature of these periods, stellar pulsations may be the origin
of some of the observed variability. Periods on the order of the
rotational period were also detected in the HeI line in the 1998-1999
season and in both lines during the 2004-2005 season. These periods
may indicate rotational modulation due to structure in the wind.
Description:
One hundred thirty spectra of ε Orionis were obtained at
Ritter Observatory using the 1m Ritchey-Chretien telescope and
fiber-fed echelle spectrograph over seven observing "seasons"
(1998-1999, 2000-2001, 2001-2002, 2002-2003, 2003-2004, 2004-2005, and
2005-2006). In Toledo, Ohio, an observing season for Orion spans
roughly from September to April. A typical season from this data set
includes ∼20 spectra, each with a signal-to-noise ratio (S/N) of ∼100
or better per pixel in the continuum. Target acquisition and manual
guiding were done with an SBIG ST-9 CCD camera. The detector for the
spectrograph was a front-illuminated EEV CCD in a Wright Instruments
camera system. The entrance slit of the spectrograph corresponded to a
resolving power R=26000. The included echelle orders overed the
spectral range from 5285 to 6594Å.
Objects:
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RA (ICRS) DE Designation(s)
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05 36 12.81 -01 12 06.9 * eps Ori = HD 37128
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 39 7 Summary of observations
table4.dat 29 131 Equivalent width and HeI radial velocity data
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See also:
B/wds : The Washington Visual Double Star Catalog (Mason+ 2001-2014)
B/gcvs : General Catalogue of Variable Stars (Samus+ 2007-2013)
III/254 : 2nd Catalog of RVs with Astrometric Data (Kharchenko+, 2007)
III/252 : Pulkovo radial velocities for 35493 HIP stars (Gontcharov, 2006)
V/125 : Photometry and Spectroscopy for Luminous Stars (Reed 2005)
III/244 : Catalog of Stellar Rotational Velocities (Glebocki+ 2005)
V/53 : Catalogue of the Brightest Stars (Ochsenbein+ 1988)
V/17 : A list of Supergiant Stars (Egret 1980)
J/ApJS/161/154 : Near-IR spectral atlas of OB stars (Hanson+, 2005)
J/A+A/384/473 : O, B and Be stars equivalent widths (Lenorzer+, 2002)
J/ApJ/573/359 : Rotational velocities of B stars from BSC (Abt+, 2002)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Season Observing season (1998-1999 to 2005-2006)
11- 12 I2 --- Ns [10/26] Number of spectra
14- 17 F4.1 d dt [6/16.5] Average interval between observations
19- 21 I3 d T [115/205] Total span of the time series
23- 28 F6.2 d Per1 [2/121]? Period of variability in HeI detected
through first run (1)
30- 33 F4.2 d Per2 [2.1/9]? Period of variability in HeI detected
through second run (1)
35- 39 F5.2 d Per3 [2.8/16]? Period of variability in HeI detected
through third run (1)
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Note (1): From the Table6 of the paper. These periods are from the radial
velocity data.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 d HJD Heliocenric Julian Date; HJD-2450000
10- 16 F7.4 0.1nm W(Ha) ? Equivalent width of Hα line (Å)
18- 22 F5.3 0.1nm W(HeI) ? Equivalent width of HeI 5876Å line (Å)
24- 29 F6.2 km/s RV [-17/22.2] Radial velocity
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 14-Apr-2014