J/A+A/550/A79 Hα and Hβ lines of northern Be stars (Catanzaro, 2013)
Spectroscopic atlas of Halpha and Hbeta in a sample of northern Be stars.
Catanzaro G.
<Astron. Astrophys. 550, A79 (2013)>
=2013A&A...550A..79C 2013A&A...550A..79C
ADC_Keywords: Stars, nearby ; Stars, Be ; Equivalent widths
Keywords: stars: emission-line, Be - stars: fundamental parameters - atlases
Abstract:
Be stars are fast rotating early-type emission line stars. It is
generally assumed that observed emission is generated in a rotating
disk- like envelope, as supported by the observed correlation between
the stellar projected rotational velocity v sin i and the width of the
emission lines. Then, high resolution spectroscopic observations of
Balmer lines profiles play an important role in putting constrains on
Be stars modeling.
We present Balmer lines spectroscopy for a sample of 48 Be stars. For
most of them, Hα and Hβ have been observed more than two
times, in a total period spanning almost two years between 2008 and
2009.
Spectral synthesis of the Hα profile has been performed
following two steps: photospheric contribution has been computed by
using Kurucz's code ATLAS9 and SYNTHE, and disk emission have been
derived by the approach of Hummel & Vrancken (1995A&A...302..751H 1995A&A...302..751H).
For 26 out of 48 stars, a modeling of the total Hα emission,
i.e. photospheric absorption plus disk net emission, has been
attempted. By this modeling we derived an estimation of the disk
radius, as well as the inclination angle between rotational axis and
line of sight and the base density at the stellar equator. We also
discussed, for the stars observed more than once, the variability of
Hα and Hβ for what concerns both the equivalent width and
the spectral profile. We found 16 stars with variable equivalent width
and 7 stars with clear sign of profile variations.
For all the stars of our sample we derive all the fundamental
astrophysical quantities, such as: effective temperature, gravity, and
projected rotational velocity. We found 13 stars which equivalent
width is variable with a confidence level greater than 80% and 7
object for which spectral profiles show change with time. According to
the classification scheme commonly used in literature, we classified
16 stars as belonging to class 1, 13 to class 2, 11 are shell stars, 6
objects do not show net emission, and 2 stars display transition from
class 1 and 2. For the class 1 stars, we confirm the correlation
between vsini and peak separation. concerning the geometry of the
disk, we derived the inclination angle between rotational axis and
line of sight, the base density at the stellar equator, and the
radius. The maximum concentration of stars occur for disk dimensions
ranging in the interval of 6 to 8 stellar radii and for inclination
angles going from 23° to 35°.
Description:
Halpha and Hbeta equivalent widths as measured in our spectra,
taken at the 91-cm telescope of the INAF Catania Astrophysical
Observatory. Negative values means that the lines show net emission.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 39 48 List of studied stars (from author)
tableb1.dat 29 171 Hα and Hβ equivalent widths for 48 stars
sp/* . 342 Individual spectra: 171 in Hα, 171 in Hβ
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See also:
J/ApJ/654/527 : Interferometric observations of northern Be stars (Gies+, 2007)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [HD]
4- 9 I6 --- HD HD number of the star
11- 12 I2 h RAh Hour of Right Ascension (J2000.0)
14- 15 I2 min RAm Minute of Right Ascension (J2000.0)
17- 24 F8.5 s RAs Second of Right Ascension (J2000.0)
26 A1 --- DE- Sign of the Declination (J2000.0)
27- 28 I2 deg DEd Degree of Declination (J2000.0)
30- 31 I2 arcmin DEm Arcminute of Declination (J2000.0)
33- 39 F7.4 arcsec DEs Arcsecond of Declination (J2000.0)
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD Henry Draper number of the star
7- 16 F10.4 d JD Heliocentric JD (JD-2450000)
17- 23 F7.2 0.1nm W(Ha) Hα equivalent width (Å)
24- 29 F6.2 0.1nm W(Hb) Hβ equivalent width (Å)
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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8- 16 F9.4 0.1nm lambda Wavelength λ (±64Å for Hα,
±100Å for Hβ)
21- 31 F11.9 --- RFlux Relative flux
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Acknowledgements:
Giovanni Catanzaro, Giovanni.Catanzaro(at)oact.inaf.it
History:
* 12-Dec-2012: Original version
* 27-Jun-2013: Added star HD45725
(End) Giovanni Catanzaro [INAF - Catania], Patricia Vannier [CDS] 12-Dec-2012