2004A&A...413..301K


C.D.S. - SIMBAD4 rel 1.7 - 2020.09.18CEST17:28:12

2004A&A...413..301K - Astronomy and Astrophysics, volume 413, 301-308 (2004/1-1)

A puzzling periodicity in the pulsating DA white dwarf G 117-B15A.

KOTAK R., VAN KERKWIJK M.H. and CLEMENS J.C.

Abstract (from CDS):

We present time-resolved optical spectrophotometry of the pulsating hydrogen atmosphere (DA) white dwarf G 117-B15A. We find three periodicities in the pulsation spectrum (215s, 272s, and 304s) all of which have been found in earlier studies. By comparing the fractional wavelength dependence of the pulsation amplitudes (chromatic amplitudes) with models, we confirm a previous report that the strongest mode, at 215s, has l=1. The chromatic amplitude for the 272s mode is very puzzling, showing an increase in fractional amplitude with wavelength that cannot be reproduced by the models for any l at optical wavelengths. Based on archival HST data, we show that while the behaviour of the 215s mode at ultra-violet wavelengths is as expected from models, the weird behaviour of the 272s periodicity is not restricted to optical wavelengths in that it fails to show the expected increase in fractional amplitude towards shorter wavelengths. We discuss possible causes for the discrepancies found for the 272s variation, but find that all are lacking, and conclude that the nature of this periodicity remains unclear.

Abstract Copyright:

Journal keyword(s): stars: white dwarfs - stars: oscillations - stars: individual: G 117-B15A

Simbad objects: 6

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Number of rows : 6

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 BD+52 913 WD* 05 05 30.6182785658 +52 49 51.920797126 10.25 11.44 11.69 11.93 12.108 DA.8 988 0
2 V* RY LMi WD* 09 24 15.2484202569 +35 16 51.400826911   15.72   15.99   DA4 248 0
3 G 117-B15B PM* 09 24 16.1666469966 +35 16 44.097681042       15.80   M3.5V 14 0
4 GD 358 WD* 16 47 18.3926893312 +32 28 32.865420612 12.511 13.530 13.653 13.752 13.852 DB2 315 0
5 V* PY Vul WD* 19 37 13.7502254298 +27 43 18.736648968   13.14   12.7   DA4.0 116 0
6 V* ZZ Psc WD* 23 28 47.6364608228 +05 14 54.234982405   13.17   13.0   DA4.1 435 0

    Equat.    Gal    SGal    Ecl

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2020.09.18-17:28:12

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