2007A&A...467..237F


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.05CEST09:18:46

2007A&A...467..237F - Astronomy and Astrophysics, volume 467, 237-248 (2007/5-3)

Asteroseismology of the PG 1159 star PG 0122+200.

FU J.-N., VAUCLAIR G., SOLHEIM J.-E., CHEVRETON M., DOLEZ N., O'BRIEN M.S., KIM S.-L., PARK B.-G., HANDLER G., MEDUPE R., WOOD M., GONZALEZ PEREZ J., HASHIMOTO O., KINUGASA K., TAGUCHI H., KAMBE E., PROVENCAL J., DREIZLER S., SCHUH S., LEIBOWITZ E., LIPKIN Y., ZHANG X.-B., PAPARO M., SZEIDL B., VIRAGHALMY G. and ZSUFFA D.

Abstract (from CDS):

The variable pre-white dwarf PG 1159 stars (GW Vir) are g-mode non-radial pulsators. Asteroseismology puts strong constraints on their global parameters and internal structure. PG 0122+200 defines the red edge of the instability strip and its evolutionary timescale is predicted to be dominated by neutrino emission. Its study offers the opportunity to better understand the instability mechanism and to validate the physics of the neutrino production in dense plasma. To achieve such a goal requires determining precisely its fundamental parameters. This is the goal of this paper. We present new multi-site photometric observations obtained in 2001 and 2002. Together with previous data, they allow us to detect 23 frequencies, composed of 7 triplets and 2 single frequencies, which are used to constrain its internal structure and derive its fundamental parameters. All the observed frequencies correspond to l=1 g-modes. The period distribution shows a signature of mode trapping from which we constrain the He-rich envelope mass fraction to be -6.0≤log(qy)≤-5.3. The comparison of the mode trapping amplitudes among GW Vir stars suggests that the mass-loss efficiency must decrease significantly below Teff≤140kK. We measure an average period spacing of 22.9s from which we derive a mass of 0.59±0.02M. From the triplets we measure a mean rotational splitting of 3.74µHz and a rotational period of 1.55-days. We derive an upper limit to the magnetic field of B≤4x103G. The luminosity (logL/L=1.3±0.5) and the distance (D=0.7+1.0–0.4kpc) are only weakly constrained due to the large uncertainty on the spectroscopically derived surface gravity and the absence of a measured parallax. From the asteroseismic mass, the ratio of the neutrino luminosity on the photon luminosity is 1.6±0.2 confirming that the PG 0122+200 evolutionary time scale should be dominated by neutrino cooling. A measurement of {dot}(P) for the largest amplitude untrapped modes should verify this prediction.

Abstract Copyright:

Journal keyword(s): stars: evolution - stars: fundamental parameters - stars: white dwarfs - stars: oscillations - stars: individual: PG 0122+200

CDS comments: paragraph 3.3 NGC 1510 is a misprint for NGC 1501. paragraph 3.5 PG 2131+427 a misprint for PG 2131+066.

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 PG 0122+200 WD* 01 25 22.5118179721 +20 17 56.963251283   16.2   16.9   DOZ.7 102 0
2 NGC 1501 PN 04 06 59.3919688584 +60 55 14.277444117   15.17 13.0     [WO4] 280 1
3 V* GW Vir WD* 12 01 45.9728868858 -03 45 40.627851273   14.87 15.04     DOQZ1 462 0
4 PG 1707+427 WD* 17 08 47.6869967260 +42 41 00.558830272   16.18       PG1159 108 0
5 MWP 1 PN 21 17 08.2817539788 +34 12 27.415871206     12.33     PG1159 173 0
6 V* IR Peg WD* 21 34 08.2124719240 +06 50 57.662044329   16.15       PG1159 111 0

    Equat.    Gal    SGal    Ecl

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2020.07.05-09:18:46

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