Query : 2008A&A...492..815T

2008A&A...492..815T - Astronomy and Astrophysics, volume 492, 815-821 (2008/12-4)

Time-resolved high-resolution spectroscopy of the bright pulsating subdwarf B star Balloon090100001.


Abstract (from CDS):

We have obtained, for the first time, a time-resolved high-resolution spectroscopic data set of the bright sdBV Balloon090100001. In the autumn of 2006 we gathered over 1600 time-resolved high-resolution spectra with the aim to identify the pulsation modes in Balloon090100001 by studying the line-profile variations. In this paper we present the results obtained from 842 spectra secured in August 2006, aiming to identify the dominant pulsation mode in this star. We phase fold the spectra onto the known dominant period of 2.80746mHz, to study the abundances and line-broadening as a function of pulsation phase. We find that the abundances do not stand out against those of other subdwarf B stars. Consequently, there is no way to demonstrate that the richness of the frequency spectrum and/or the high pulsation amplitudes are related to abundance effects. The abundances do not change with pulsational phase. The metal lines in Balloon090100001 are much broader than for non-pulsating subdwarfs, and during the cycle of the main pulsation the line broadening varies with ∼2.5km/s amplitude. Hence, we find clear evidence of pulsational broadening of the lines. We combine the information content of 56 narrow absorption lines through a cross-correlation technique, to create cross-correlation functions that for each individual pulsation phase approximate the average line-profile shape. The resulting profiles have a sufficient signal-to-noise ratio for a mode-identification analysis. From the cross-correlation analysis we find that the pulsation amplitude of the main mode decreased from 19km/s in 2004 to 14.5km/s in 2006. We present, for an sdB star, the first application of pulsation-mode identification based on line-profile variations of lines of heavy elements. To fit the line profiles we consider all modes with degree l≤2 and associated azimuthal order m, and we use a model of the pulsational surface-velocity field. The models with l=2 do not fit the profiles well, and consequently we can rule out quadrupole modes as the origin of the main pulsation mode in Balloon 090100001. Best fits are obtained from the model of a radial pulsation (l=0) and the model of a dipole pulsation (l=1).

Abstract Copyright:

Journal keyword(s): stars: subdwarfs - line: profiles - stars: early-type - stars: oscillations - stars: variables: general - stars: individual: Balloon090100001

CDS comments: Paragraph.1 KPD 1209+4401 is a misprint for KPD 2109+4401.

Simbad objects: 7

goto Full paper

goto View the references in ADS

Number of rows : 7
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 V* EO Cet HS* 01 23 43.2471248112 -05 05 45.831024564   12.21 12.65     sdOV+F4V 63 0
2 Feige 48 HS* 11 47 14.4978515760 +61 15 31.789400364   13.12 13.28     sdB 114 0
3 PG 1325+102 HS* 13 27 48.5600155368 +09 54 51.049107756   13.73 13.98 14.29   sdBO 54 1
4 V* NY Vir HS* 13 38 48.1466908176 -02 01 49.207286748   13.43 13.66 13.75   sdB1VIIHe1 211 1
5 PG 1605+072 HS* 16 08 03.6872637792 +07 04 28.748468964   12.53 12.83 13.18   sdB0.2VIHe3 126 0
6 KPD 2109+4401 HS* 21 11 47.6445824136 +44 13 50.620755936 12.14 13.11 13.30 13.64   sdB 64 0
7 Balloon 90100001 HS* 23 15 21.4810390968 +29 05 01.433373360   11.90 12.30     sdB 87 0

To bookmark this query, right click on this link: simbad:objects in 2008A&A...492..815T and select 'bookmark this link' or equivalent in the popup menu


© Université de Strasbourg/CNRS

    • Contact