2014A&A...570A.129T


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.14CEST18:34:11

2014A&A...570A.129T - Astronomy and Astrophysics, volume 570A, 129-129 (2014/10-1)

KIC 7668647: a 14 day beaming sdB+WD binary with a pulsating subdwarf.

TELTING J.H., BARAN A.S., NEMETH P., OSTENSEN R.H., KUPFER T., MacFARLANE S., HEBER U., AERTS C. and GEIER S.

Abstract (from CDS):

The recently discovered subdwarf B (sdB) pulsator KIC7668647 is one of the 18 pulsating sdB stars detected in the Kepler field. It features a rich g-mode frequency spectrum, with a few low-amplitude p-modes at short periods. This makes it a promising target for a seismic study aiming to constrain the internal structure of this star, and of sdB stars in general. We use new ground-based low-resolution spectroscopy, and the near-continuous 2.88year Kepler light curve, to reveal that KIC7668647 consists of a subdwarf B star with an unseen white-dwarf companion with an orbital period of 14.2d. An orbit with a radial-velocity amplitude of 39km/s is consistently determined from the spectra, from the orbital Doppler beaming seen by Kepler at 163ppm, and from measuring the orbital light-travel delay of 27s by timing of the many pulsations seen in the Kepler light curve. The white dwarf has a minimum mass of 0.40M. We use our high signal-to-noise average spectra to study the atmospheric parameters of the sdB star, and find that nitrogen and iron have abundances close to solar values, while helium, carbon, oxygen and silicon are underabundant relative to the solar mixture. We use the full Kepler Q06-Q17 light curve to extract 132 significant pulsation frequencies. Period-spacing relations and multiplet splittings allow us to identify the modal degree l for the majority of the modes. Using the g-mode multiplet splittings we constrain the internal rotation period at the base of the envelope to 46-48d as a first seismic result for this star. The few p-mode splittings may point at a slightly longer rotation period further out in the envelope of the star. From mode-visibility considerations we derive that the inclination of the rotation axis of the sdB in KIC7668647 must be around ∼60°. Furthermore, we find strong evidence for a few multiplets indicative of degree 3 ≤l≤8, which is another novelty in sdB-star observations made possible by Kepler.

Abstract Copyright:

Journal keyword(s): subdwarfs - stars: early-type - binaries: spectroscopic - stars: oscillations - stars: individual: KIC 7668647 - stars: variables: general

Simbad objects: 12

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Number of rows : 12

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 * ome Sco bC* 16 06 48.4269211 -20 40 09.090235 3.10 3.92 3.97 3.91 3.99 B1V 437 0
2 FBS 1903+432 HS* 19 05 06.3764795541 +43 18 31.219151136   15.08 15.48     sdB 24 1
3 KIC 1718290 HB* 19 23 00.6774105516 +37 15 04.492365860           ~ 13 0
4 KIC 10139564 HS* 19 24 58.1495860117 +47 07 53.671623446           sdB 27 0
5 KIC 11558725 HS* 19 26 34.1086786586 +49 30 29.559195885           sdB 27 1
6 KIC 2991276 HS* 19 27 09.1455863407 +38 10 26.391506943   17.2   17.3   sdB 13 0
7 KIC 10670103 HS* 19 34 39.9403831100 +47 58 11.534601872           sdB 19 1
8 Kepler-70 HS* 19 45 25.4746134531 +41 05 33.882016627 13.80 14.71 14.87 15.43 15.72 sdB 60 1
9 TYC 3148-1212-1 EB* 19 45 54.5531633235 +43 28 29.164942285   12.37 12.42     A9III 6 0
10 KPD 1946+4340 HS* 19 47 42.8878643003 +43 47 30.757113602 13.05 14.06 14.23 14.92   sdOB+D 47 0
11 KIC 10553698 HS* 19 53 08.3855210679 +47 43 00.181310721           sdB 18 1
12 V* EQ Psc HS* 23 34 34.6311490938 -01 19 36.930185932     13.06     sdB 19 0

    Equat.    Gal    SGal    Ecl

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2020.07.14-18:34:11

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