A Quantitative Analysis of the Available Multicolor Photometry for Rapidly Pulsating Hot B Subdwarfs

Abstract

We present a quantitative and homogeneous analysis of the broadband multicolor photometric data sets gathered so far on rapidly pulsating hot B subdwarf stars. This concerns seven distinct data sets related to six different stars. Our analysis is carried out within the theoretical framework developed by Randall et al., which includes full nonadiabatic effects. The goal of this analysis is partial mode identification, i.e., the determination of the degree index l of each of the observed pulsation modes. We assume possible values of l from 0 to 5 in our calculations. For each target star, we compute a specific model atmosphere and a specific pulsation model using estimates of the atmospheric parameters coming from time-averaged optical spectroscopy. For every assumed value of l, we use a formal chi-squared approach to model the observed amplitude-wavelength distribution of each mode, and we compute a quality-of-fit Q probability to quantify the derived fit and to discriminate objectively between the various solutions. We find that no completely convincing and unambiguous l identification is possible on the basis of the available data, although partial mode discrimination has been reached for 25 out of the 41 modes studied. A brief statistical study of these results suggests that a majority of the modes must have l values of 0, 1, and 2, but also that modes with l = 4 could very well be present while modes with l = 3 appear to be rarer. This is in line with recent results showing that l = 4 modes in rapidly pulsating B subdwarfs have a higher visibility in the optical domain than modes with l = 3. Although somewhat disappointing in terms of mode discrimination, our results still suggest that the full potential of multicolor photometry for l identification in pulsating subdwarfs is within reach.

59 pages, 18 figures, accepted for publication in the Astrophysical Journal Supplement Series

References in corpus (5)

• Structural Parameters of the Hot Pulsating B Subdwarf PG 1219+534 from Asteroseismology
• A photometric mode identification method, including an improved non-adiabatic treatment of the atmosphere
• The Potential of Multi-Colour Photometry for Pulsating Subdwarf B Stars
• Multicolour photometry of Balloon 090100001: linking the two classes of pulsating hot subdwarfs
• Simultaneous time-series spectroscopy and multi-band photometry of the sdBV PG 1605+072

Cited by in corpus (9)

• Hot subluminous stars
• Asteroseismology and Interferometry
• Third generation stellar models for asteroseismology of hot B subdwarf stars. A test of accuracy with the pulsating eclipsing binary PG 1336--018
• Stellar variability in open clusters. I. A new class of variable stars in NGC 3766
• Mode identification for Balloon 090100001 using combined multicolour photometry and spectroscopy
• Observations and asteroseismic analysis of the rapidly pulsating hot B subdwarf PG 0911+456
• Photometry and spectroscopy of the new sdBV CS 1246
• RAT J0455+1305: A rare hybrid pulsating subdwarf B star
• Mode identification from monochromatic amplitude and phase variations for the rapidly pulsating subdwarf B star EC 20338-1925