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Spectrum Variability for the HgMn Star alpha And

Wahlgren, Glenn LU ; Ilyin, I. and Kochukhov, O. (2001) In Bulletin of the American Astronomical Society 33(4). p.1506-1506
Abstract
The detection of spectral line profile variability for stars of the HgMnclass of chemical peculiarity has been poorly documented in theliterature yet holds a special significance for understandingrelationships between observed spectral anomalies, stellar surfacestructure, and magnetic fields. The HgMn stars have until now not beenconfirmed to vary in their light or spectral characteristics in waysunattributable to binarity, as opposed to the classical Ap stars forwhich such variations are explainable by the magnetic oblique rotatormodel. Alpha And (V = 2.1 mag, B8IVp HgMn) is a bright, prototypicalHgMn star in a binary system of orbital period 96.8 days. Severalauthors have singled out this star as having line profile variations,but most... (More)
The detection of spectral line profile variability for stars of the HgMnclass of chemical peculiarity has been poorly documented in theliterature yet holds a special significance for understandingrelationships between observed spectral anomalies, stellar surfacestructure, and magnetic fields. The HgMn stars have until now not beenconfirmed to vary in their light or spectral characteristics in waysunattributable to binarity, as opposed to the classical Ap stars forwhich such variations are explainable by the magnetic oblique rotatormodel. Alpha And (V = 2.1 mag, B8IVp HgMn) is a bright, prototypicalHgMn star in a binary system of orbital period 96.8 days. Severalauthors have singled out this star as having line profile variations,but most of these reports are purely suggestive. We have made spectralobservations of alpha And during the observing seasons 1999, 2000, and2001. The spectra were taken using resolving powers of R = 25000 and80000, and were especially directed toward detection of variations inthe line Hg II 3984 Å, for which Ryabchikova et al. (1999) note apossible variation. Radial velocity measurements of our data were usedto enhance the binary orbital solution. From a periodogram of this Hg IIline in our data a consistent peak is evident for a period ofapproximately 2.38 days, which we interpret to be the rotational periodof the primary star. When all high resolution spectra are binned byphase according to this period the Hg II line profile displays anundulating nature with the line width at the continuum level notvarying. Results from our Doppler image mapping show surface structuresof a similar nature to those observed for magnetic Ap stars. We continueto analyse the spectra in a search for variability of other spectrallines, the direct determination of a magnetic field, and thecharacterization of the surface distribution of the elements. (Less)
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Bulletin of the American Astronomical Society
volume
33
issue
4
pages
1506 - 1506
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The American Astronomical Society
language
English
LU publication?
yes
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0b4233f2-9165-42b7-af6b-375c051236da (old id 527830)
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http://www.aas.org/publications/baas/v33n4/aas199/296.htm
date added to LUP
2007-09-25 13:41:29
date last changed
2016-04-16 09:28:28
@misc{0b4233f2-9165-42b7-af6b-375c051236da,
  abstract     = {The detection of spectral line profile variability for stars of the HgMnclass of chemical peculiarity has been poorly documented in theliterature yet holds a special significance for understandingrelationships between observed spectral anomalies, stellar surfacestructure, and magnetic fields. The HgMn stars have until now not beenconfirmed to vary in their light or spectral characteristics in waysunattributable to binarity, as opposed to the classical Ap stars forwhich such variations are explainable by the magnetic oblique rotatormodel. Alpha And (V = 2.1 mag, B8IVp HgMn) is a bright, prototypicalHgMn star in a binary system of orbital period 96.8 days. Severalauthors have singled out this star as having line profile variations,but most of these reports are purely suggestive. We have made spectralobservations of alpha And during the observing seasons 1999, 2000, and2001. The spectra were taken using resolving powers of R = 25000 and80000, and were especially directed toward detection of variations inthe line Hg II 3984 Å, for which Ryabchikova et al. (1999) note apossible variation. Radial velocity measurements of our data were usedto enhance the binary orbital solution. From a periodogram of this Hg IIline in our data a consistent peak is evident for a period ofapproximately 2.38 days, which we interpret to be the rotational periodof the primary star. When all high resolution spectra are binned byphase according to this period the Hg II line profile displays anundulating nature with the line width at the continuum level notvarying. Results from our Doppler image mapping show surface structuresof a similar nature to those observed for magnetic Ap stars. We continueto analyse the spectra in a search for variability of other spectrallines, the direct determination of a magnetic field, and thecharacterization of the surface distribution of the elements.},
  author       = {Wahlgren, Glenn and Ilyin, I. and Kochukhov, O.},
  language     = {eng},
  number       = {4},
  pages        = {1506--1506},
  publisher    = {ARRAY(0xb1a1d58)},
  series       = {Bulletin of the American Astronomical Society},
  title        = {Spectrum Variability for the HgMn Star alpha And},
  volume       = {33},
  year         = {2001},
}