2021A&A...655A..27U


Query : 2021A&A...655A..27U

2021A&A...655A..27U - Astronomy and Astrophysics, volume 655A, 27-27 (2021/11-1)

Pulsating hydrogen-deficient white dwarfs and pre-white dwarfs observed with TESS. II. Discovery of two new GW Vir stars: TIC 333432673 and TIC 095332541.

UZUNDAG M., CORSICO A.H., KEPLER S.O., ALTHAUS L.G., WERNER K., REINDL N., BELL K.J., HIGGINS M., DA ROSA G.O., VUCKOVIC M. and ISTRATE A.

Abstract (from CDS):


Context. The Transiting Exoplanet Survey Satellite (TESS) mission is revolutionizing the blossoming area of asteroseismology, particularly of pulsating white dwarfs and pre-white dwarfs, thus continuing the impulse of its predecessor, the Kepler mission.
Aims. In this paper, we present the observations from the extended TESS mission in both 120 s short-cadence and 20 s ultra-short-cadence mode of two pre-white dwarf stars showing hydrogen deficiency. We identify them as two new GW Vir stars, TIC 333432673 and TIC 095332541. We apply the tools of asteroseismology with the aim of deriving their structural parameters and seismological distances.
Methods. We carried out a spectroscopic analysis and a spectral fitting of TIC 333432673 and TIC 095332541. We also processed and analyzed the high-precision TESS photometric light curves of the two target stars, and derived their oscillation frequencies. We performed an asteroseismological analysis of these stars on the basis of PG 1159 evolutionary models that take into account the complete evolution of the progenitor stars. We searched for patterns of uniform period spacings in order to constrain the stellar mass of the stars. We employed the individual observed periods to search for a representative seismological model.
Results. The analysis of the TESS light curves of TIC 333432673 and TIC 095332541 reveals the presence of several oscillations with periods ranging from 350 to 500 s associated to typical gravity (g)-modes. From follow-up ground-based spectroscopy, we find that both stars have a similar effective temperature (Teff=120000±10000K) and surface gravity (logg=7.5±0.5), but a different He/C composition of their atmosphere. On the basis of PG 1159 evolutionary tracks, we derived a spectroscopic mass of M*=0.58–0.08+0.16M for both stars. Our asteroseismological analysis of TIC 333432673 allowed us to find a constant period spacing compatible with a stellar mass M*∼0.60-0.61M, and an asteroseismological model for this star with a stellar mass M*=0.589±0.020M, as well as a seismological distance of d=459–156+188dpc. For this star, we find an excellent agreement between the different methods to infer the stellar mass, and also between the seismological distance and that measured with Gaia (dGaia=389–5.2+5.6pc). For TIC 095332541, we have found a possible period spacing that suggests a stellar mass of M*∼0.55-0.57M. Unfortunately, we have not been able to find an asteroseismological model for this star.
Conclusions. Using the high-quality data collected by the TESS space mission and follow-up spectroscopy, we have been able to discover and characterize two new GW Vir stars. The TESS mission is having, and will continue to have, an unprecedented impact on the area of white-dwarf asteroseismology.

Abstract Copyright: © ESO 2021

Journal keyword(s): asteroseismology - stars: oscillations - stars: interiors - stars: evolution - white dwarfs

CDS comments: Fig.5 some objects not in SIMBAD (incomplete format)

Simbad objects: 42

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Number of rows : 42
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 PB 5835 WD* 00 16 51.4153668936 -01 13 29.300107908   16   17.41   PG1159 22 0
2 ACO 21 ClG 00 20 38.75 +28 41 40.5           ~ 106 0
3 ACO 43 ClG 00 28 54 +17 34.6           ~ 19 0
4 NGC 246 PN 00 47 03.3420341616 -11 52 18.971126076 10.15 11.52 11.76 12.18   PG1159 475 0
5 RX J0122.9-7521 WD* 01 22 53.4122561952 -75 21 14.724358308     15.4     PG1159 43 0
6 PG 0122+200 WD* 01 25 22.5121704552 +20 17 56.963079924   16.2   16.9   DOZ.7 112 0
7 LB 3218 WD* 01 31 58.2906246552 -68 31 14.512456056 13.47 14.53 14.78 15.13   DA1.4 10 0
8 V* ZZ Cet WD* 01 36 13.6153974672 -11 20 32.632874601   14.328 14.16 14.4   DA4.0 291 0
9 M 76 PN 01 42 19.6557728208 +51 34 31.534970052     17.48   17.69 DOZ 374 2
10 KUV 03467-0108 WD* 03 49 17.4089215872 -00 59 19.230310320   18.0       PG1159 22 1
11 NGC 1501 PN 04 06 59.3920909320 +60 55 14.278542024   15.17 13.0     [WO4] 296 1
12 HS 0444+0453 WD* 04 47 04.5045887496 +04 58 41.340500616   15.9   16.1   DQZO.5 26 0
13 UCAC4 381-011163 WD* 06 02 44.9873863680 -13 51 03.560070204   15.115 15.351 15.406   DOZ 6 0
14 UCAC4 382-016680 WD? 06 41 15.6438988128 -13 41 23.769313584   14.593 14.380 15.775   ~ 6 0
15 HS 0704+6153 WD* 07 09 32.4965901360 +61 48 19.458822312   17.3   17.1   PG1159 40 0
16 WRAY 17-1 PN 07 14 49.4240697984 -46 57 39.199063500   13.8 13.00     PG1159 83 0
17 NGC 2371 PN 07 25 34.6883929008 +29 29 26.430252072   14.48 13.5     Oe 367 0
18 GALEX J075415.1+085232 WD* 07 54 15.1178449560 +08 52 32.192959728           PG1159 15 0
19 KUV 07523+4017 WD* 07 55 40.9407521736 +40 09 17.910022752   17.00 17.53     PG1159 22 0
20 GALEX J093546.5+110529 WD* 09 35 46.5393775728 +11 05 28.911314760           PG1159 18 0
21 PN Lo 4 PN 10 05 45.7880109408 -44 21 33.523482384           sdO 139 1
22 SBSS 1020+541 WD* 10 23 27.4218578112 +53 52 58.706674968   17.5 17.91     PG1159 22 0
23 PG 1144+005 WD* 11 46 35.2284791112 +00 12 33.539992056   14.922 15.233     PG1159 89 0
24 V* GW Vir WD* 12 01 45.9731868264 -03 45 40.628670300   14.87 15.04     DOQZ1 490 0
25 ESO 576-2 IG 13 10 28.8 -21 35 12           ~ 8 0
26 FBS 1342+673 WD* 13 43 41.8834097904 +67 01 54.512227344           PG1159 23 0
27 PG 1424+535 WD* 14 25 55.4615842224 +53 15 25.138507140   15.412 15.963     PG1159 75 0
28 HE 1429-1209 WD* 14 32 20.7451392024 -12 22 48.253478808   15.7 16.15 16.27   PG1159 27 0
29 SBSS 1446+575 WD* 14 47 34.1180967672 +57 20 53.108181168   17.28 18.05     PG1159 18 0
30 HS 1517+7403 WD* 15 16 46.4260387056 +73 52 06.953282400   16.4   16.9   DO 41 0
31 PG 1520+447 WD* 15 22 17.1743287392 +44 32 55.446411120   16.56 16.58     DA2.8 27 0
32 CD-38 10980 WD* 16 23 33.8380498896 -39 13 46.161043572 9.916 10.885 11.029 10.936 10.841 DA2 484 0
33 GD 358 WD* 16 47 18.3925183824 +32 28 32.862804384 12.511 13.530 13.653 13.752 13.852 DB2 350 0
34 PG 1707+427 WD* 17 08 47.6869215528 +42 41 00.558430656           PG1159 116 0
35 PN K 1-16 PN 18 21 52.1086837968 +64 21 53.406292104   14.44 14.96 15.26   PG1159 250 0
36 SH 2-68 PN 18 24 58.4294414904 +00 51 36.021249072   16.0 16.5     DAOZ.6 130 1
37 NGC 6905 PN 20 22 22.9919225472 +20 06 16.285052088   16.3 14.5     [WC3] 346 0
38 MWP 1 PN 21 17 08.2817782392 +34 12 27.415995372     12.33     PG1159 186 0
39 V* IR Peg WD* 21 34 08.2124719240 +06 50 57.662044329   16.15       PG1159 118 0
40 NGC 7094 PN 21 36 52.9687364088 +12 47 19.099274136     13.650 13.775   sdB/sdO 194 0
41 V* V409 And WD* 23 27 15.9353097240 +40 01 23.429781408   14.1 15.41     DO 79 0
42 PN Jn 1 PN 23 35 53.3214838680 +30 28 06.336745212   15.52 15.62     DOZ 107 0

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