2011A&A...532A...7K


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.08CEST03:26:26

2011A&A...532A...7K - Astronomy and Astrophysics, volume 532A, 7-7 (2011/8-1)

The cool magnetic DAZ white dwarf NLTT 10480.

KAWKA A. and VENNES S.

Abstract (from CDS):

We have identified a new cool magnetic white dwarf in the New Luyten Two-Tenths (NLTT) catalogue. The high proper-motion star NLTT 10480 (µ=0.5''/yr) shows weak Zeeman-split lines of calcium as well as characteristic Hα and β Zeeman triplets. Using VLT X-shooter spectra, we measured a surface-averaged magnetic field BS∼0.5MG. The relative intensity of the π and σ components of the calcium and hydrogen lines imply a high inclination (iγ60°). The optical-to-infrared V-J colour index and the CaI/CaII ionization balance indicate a temperature between 4900 and 5200K, while the Balmer line profiles favour a higher temperature of 5400K. The discrepancy is potentially resolved by increasing the metallicity to 0.03xsolar, hence increasing the electron pressure. However, the measured calcium abundance and abundance upper limits for other elements (Na, Al, Si, and Fe) imply a low photospheric metallicity ≲10–4 solar. Assuming diffusion steady-state, a calcium accretion rate of log{dot}(M)(g/s)=5.6±0.3 is required to sustain a calcium abundance of logn(Ca)/n(H)=-10.30±0.30 in the white dwarf atmosphere. We examine the implications of this discovery for the incidence of planetary debris and weak magnetic fields in cool white dwarf stars.

Abstract Copyright:

Journal keyword(s): white dwarfs - stars: individual: NLTT 10480 - stars: atmospheres - stars: abundances

Simbad objects: 7

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Number of rows : 7

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 EGGR 473 WD* 02 48 36.4289567406 +54 23 22.463731008   16.25   15.1   DAZ9 54 0
2 LP 887-66 WD* 03 17 12.0973945044 -29 11 34.211376143   17.6 17.49     DAZ 16 0
3 EGGR 566 WD* 03 25 11.0473248379 -01 49 15.047384952   16.8 16.22     DAZ 68 0
4 LP 614-59 WD* 12 14 56.3832862079 -02 34 02.838161706   17.7 17.85     DZP 24 0
5 G 165-7 WD* 13 30 59.4185219799 +30 29 53.651634272   16.73 16.04 15.74 15.60 DZ7 63 0
6 LAWD 83 WD* 21 13 16.8542099131 -81 49 12.878202704 13.28 13.82 13.59 13.6   DA4.8 83 0
7 Feige 110 HS* 23 19 58.3995050606 -05 09 56.170282845 10.360 11.45 11.50 11.970 12.145 sdO8VIIIHe5 552 1

    Equat.    Gal    SGal    Ecl

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2020.07.08-03:26:26

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