2013A&A...550L..10G


C.D.S. - SIMBAD4 rel 1.7 - 2020.05.29CEST03:19:16

2013A&A...550L..10G - Astronomy and Astrophysics, volume 550, L10-10 (2013/2-1)

Understanding the dynamical structure of pulsating stars: the Baade-Wesselink projection factor of the δ Scuti stars. AI Velorum and β Cassiopeiae.

GUIGLION G., NARDETTO N., MATHIAS P., DOMICIANO DE SOUZA A., PORETTI E., RAINER M., FOKIN A., MOURARD D. and GIEREN W.

Abstract (from CDS):

The Baade-Wesselink method of distance determination is based on the oscillations of pulsating stars. The key parameter of this method is the projection factor used to convert the radial velocity into the pulsation velocity. Our analysis was aimed at deriving for the first time the projection factor of δ Scuti stars, using high-resolution spectra of the high-amplitude pulsator AI Vel and of the fast rotator β Cas. The geometric component of the projection factor (i.e. p0) was calculated using a limb-darkening model of the intensity distribution for AI Vel, and a fast-rotator model for β Cas. Then, using SOPHIE/OHP data for β Cas and HARPS/ESO data for AI Vel, we compared the radial velocity curves of several spectral lines forming at different levels in the atmosphere and derived the velocity gradient associated to the spectral-line-forming regions in the atmosphere of the star. This velocity gradient was used to derive a dynamical projection factor p. We find a flat velocity gradient for both stars and finally p=p0=1.44 for AI Vel and p=p0=1.41 for β Cas. By comparing Cepheids and δScuti stars, these results bring valuable insights into the dynamical structure of pulsating star atmospheres. They suggest that the period-projection factor relation derived for Cepheids is also applicable to δScuti stars pulsating in a dominant radial mode.

Abstract Copyright:

Journal keyword(s): stars: oscillations - stars: atmospheres - stars: variables: δ Scuti - techniques: spectroscopic

Status at CDS:  

Simbad objects: 4

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Number of rows : 4

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 * bet Cas dS* 00 09 10.68518 +59 08 59.2120 2.73 2.61 2.27 1.97 1.77 F2III 495 0
2 V* AI Vel dS* 08 14 05.1458681791 -44 34 32.852065552   6.98 6.70     A9IV/V 178 0
3 NAME Vir I ClG 12 26 32.1 +12 43 24   10.00 8.49     ~ 5794 0
4 * alf Lup bC* 14 41 55.7557866 -47 23 17.515486 1.22 2.126 2.286     B1.5III 223 0

    Equat.    Gal    SGal    Ecl

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2020.05.29-03:19:16

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