2011A&A...530A.114K


Query : 2011A&A...530A.114K

2011A&A...530A.114K - Astronomy and Astrophysics, volume 530A, 114-114 (2011/6-1)

Cool DZ white dwarfs in the SDSS.

KOESTER D., GIRVEN J., GAENSICKE B.T. and DUFOUR P.

Abstract (from CDS):

We report the identification of 26 cool DZ white dwarfs that lie across and below the main sequence in the Sloan Digital Sky Survey (SDSS) (u-g) vs. (g-r) two-color diagram; 21 of these stars are new discoveries. The sample was identified by visual inspection of all spectra of objects that fall below the main sequence in the two-color diagram, as well as by an automated search for characteristic spectral features over a large area in color space that included the main sequence. The spectra and photometry provided by the SDSS project are interpreted with model atmospheres, including all relevant metals. Effective temperatures and element abundances are determined, while the surface gravity has to be assumed and was fixed at the canonical value of logg=8.These stars represent the extension of the well-known DZ sequence towards cooler temperatures and fill the gap around Teff=6500K present in a previous study. The metal abundances are similar to those in the hotter DZ, but the lowest abundances are missing, probably because of our selection procedures. The interpretation is complicated in terms of the accretion/diffusion scenario, because we do not know if accretion is still occurring or has ended long ago. Independent of that uncertainty, the masses of the metals currently present in the convection zones - and thus an absolute lower limit of the total accreted masses - of these stars are similar to the largest asteroids in our solar system.

Abstract Copyright:

Journal keyword(s): white dwarfs - stars: abundances - accretion, accretion disks - diffusion - line: profiles

Simbad objects: 30

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Number of rows : 30
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 SDSS J014300.52+011356.8 WD* 01 43 00.5240622768 +01 13 56.986794732           DZ 11 0
2 SDSS J015748.15+003315.2 WD* 01 57 48.1464846312 +00 33 15.140599164           DZP 15 0
3 SDSS J020534.13+215559.7 WD* 02 05 34.0861360032 +21 55 59.585523420           DZ 11 0
4 GD 40 WD* 03 02 53.1037481136 -01 08 33.798683976   15.51 15.56     DBZ4 165 0
5 EGGR 566 WD* 03 25 11.0474878302 -01 49 15.047041848   16.8 16.22     DZA9 76 0
6 GALEX J073842.6+183509 WD* 07 38 42.5662133112 +18 35 09.713206464           DBZ 56 0
7 LP 369-22 WD* 09 16 21.3076471560 +25 40 29.103778164   18.3   17.6   DZ 19 0
8 SDSS J092523.10+313019.0 WD* 09 25 23.1022854984 +31 30 19.600121808           DZ 9 0
9 SDSS J093719.14+522802.3 WD* 09 37 19.1560872984 +52 28 02.329951548           DZ 15 0
10 GALEX J095645.1+591241 WD* 09 56 45.1467202896 +59 12 40.638553884           DZA 25 0
11 GALEX J103809.1-003622 WD* 10 38 09.1869876816 -00 36 22.450492872   17.3   16.7   DZ 24 0
12 LP 372-53 WD* 10 40 46.5185417784 +24 08 00.171882924   19.7   18.9   DZ 15 0
13 SDSS J104319.84+351641.6 WD* 10 43 19.8692704656 +35 16 42.087943704           DZ 17 0
14 SDSS J110304.15+414434.9 WD* 11 03 04.1633710728 +41 44 35.052082260           DZ 10 0
15 LSPM J1144+1218 WD* 11 44 41.8898659872 +12 18 29.349168912   18.4   17.9   DZ 12 0
16 SDSS J115224.51+160546.7 WD* 11 52 24.5044149840 +16 05 46.805925768           DZP 8 0
17 GALEX J123415.3+520808 WD* 12 34 15.2001220800 +52 08 08.304344412           DZ 12 0
18 G 165-7 WD* 13 30 59.4185829051 +30 29 53.651822645   16.73 16.04 15.74 15.60 DZ7 78 0
19 SDSS J133624.26+354751.2 WD* 13 36 24.2727178272 +35 47 51.702550044           DZ 12 0
20 SDSS J135632.63+241606.0 WD* 13 56 32.5998388536 +24 16 06.268600452   19.53 19.20     DZ 11 0
21 LSPM J1404+3620 WD* 14 04 10.7652993744 +36 20 57.117681024   19.1   18.6   DZ 15 0
22 SDSS J140557.10+154940.5 WD* 14 05 57.1326322368 +15 49 40.558656288           DZ 11 0
23 SDSS J142120.11+184351.6 WD* 14 21 20.1262293264 +18 43 51.714943068           DZ 9 0
24 SDSS J143007.15-015129.5 WD* 14 30 07.1600327016 -01 51 29.670636348           DZ 10 0
25 SDSS J152449.58+404938.1 WD* 15 24 49.5779469336 +40 49 38.077809024           DZ 12 0
26 G 137-24 WD* 15 35 05.8098944592 +12 47 45.199307508   15.31   15.7   DZ 39 0
27 SDSS J154625.33+300946.2 WD* 15 46 25.3451203752 +30 09 46.259533512           DZ 9 0
28 GALEX J155429.0+173547 WD* 15 54 29.0040390648 +17 35 46.536316368           DZ 14 0
29 SDSS J161603.00+330301.2 WD* 16 16 03.0095555280 +33 03 01.126782144           DZ 10 0
30 SDSS J234048.74+081753.3 WD* 23 40 48.6799720344 +08 17 53.199812760           DZ 10 0

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