2007ApJ...663.1291D


C.D.S. - SIMBAD4 rel 1.7 - 2021.05.16CEST20:46:30

2007ApJ...663.1291D - Astrophys. J., 663, 1291-1308 (2007/July-2)

On the spectral evolution of cool, helium-atmosphere white dwarfs: detailed spectroscopic and photometric analysis of DZ stars.

DUFOUR P., BERGERON P., LIEBERT J., HARRIS H.C., KNAPP G.R., ANDERSON S.F., HALL P.B., STRAUSS M.A., COLLINGE M.J. and EDWARDS M.C.

Abstract (from CDS):

We present a detailed analysis of a large spectroscopic and photometric sample of DZ white dwarfs based on our latest model atmosphere calculations. We revise the atmospheric parameters of the trigonometric parallax sample of Bergeron, Leggett, & Ruiz (12 stars) and analyze 147 new DZ white dwarfs discovered in the SDSS. The inclusion of metals and hydrogen in our model atmosphere calculations leads to different atmospheric parameters than those derived from pure helium models. Calcium abundances are found in the range from log(Ca/He)=-12 to -8. We also find that fits of the coolest objects show peculiarities, suggesting that our physical models may not correctly describe the conditions of high atmospheric pressure encountered in the coolest DZ stars. We find that the mean mass of the 11 DZ stars with trigonometric parallaxes, <M≥0.63 M, is significantly lower than that obtained from pure helium models, <M≥0.78 M, and in much better agreement with the mean mass of other types of white dwarfs. We determine hydrogen abundances for 27% of the DZ stars in our sample, while only upper limits are obtained for objects with low-S/N spectroscopic data. We confirm with a high level of confidence that the accretion rate of hydrogen is at least 2 orders of magnitude smaller than that of metals (and up to 5 in some cases) to be compatible with the observations. We find a correlation between the hydrogen abundance and the effective temperature, suggesting for the first time empirical evidence of a lower temperature boundary for the hydrogen screening mechanism. Finally, we speculate on the possibility that the DZA white dwarfs could be the result of the convective mixing of thin hydrogen-rich atmospheres with the underlying helium convection zone.

Abstract Copyright:

Journal keyword(s): Stars: Abundances - Stars: Atmospheres - Stars: Evolution - Stars: White Dwarfs

VizieR on-line data: <Available at CDS (J/ApJ/663/1291): table2.dat>

CDS comments: Parag. 5.4 : PG 2224+034 is a misprint for PG 2234+034

Simbad objects: 160

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Number of rows : 160

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 PB 5726 WD* 00 05 57.2290720391 +00 18 33.248961930   19   19.3   DZ 15 0
2 PB 5858 WD* 00 18 49.4339694593 -00 12 04.769052632   18.5       DZ 8 2
3 PB 8392 WD* 00 36 01.3738928432 -11 12 14.013304533   17       DZ 13 0
4 SDSS J004123.58+151109.0 WD* 00 41 23.5900745755 +15 11 09.100316828           DZ 7 0
5 SDSS J004646.15+002430.9 WD* 00 46 46.1573622296 +00 24 30.931509553           DZ 4 0
6 Wolf 28 WD* 00 49 09.8984116191 +05 23 18.993107442 12.984 12.92 12.374 12.106 11.854 DZ7.5 223 0
7 SDSS J005906.77+001725.2 WD* 00 59 06.7748844776 +00 17 25.261222009           DZ 9 0
8 WD 0103-013 WD* 01 06 29.8518264224 -01 03 44.381810204           DZA 8 0
9 2SLAQ J011338.35-000632.9 WD* 01 13 38.3620152331 -00 06 32.863249531           DZ 5 1
10 PB 8618 WD* 01 13 58.9858196981 -09 59 13.335287141   18   18.11   DZA 10 0
11 SDSS J012339.77+132433.4 WD* 01 23 39.7598595739 +13 24 33.540032753           DZ 7 0
12 SDSS J013831.12+003101.6 WD* 01 38 31.1287232980 +00 31 01.676754417           DZ 4 0
13 PB 6561 WD* 02 00 02.0093700577 +00 40 18.398262926   19       DZ 7 0
14 PB 6582 WD* 02 01 32.2386049974 -00 39 32.157886336   17.5       DZ 11 0
15 PHL 1255 WD* 02 18 36.6941376017 -09 19 44.937162813   18.1 18.2     DZ 10 0
16 SDSS J022851.97-000938.7 WD* 02 28 51.9723708090 -00 09 38.784391011           DZ 8 0
17 SDSS J030800.40-065659.9 WD* 03 08 00.3958841424 -06 57 00.078911902           DZ 7 0
18 SDSS J031448.25-082755.3 WD* 03 14 48.2610874513 -08 27 55.251027645           DZ 5 0
19 SDSS J041145.90-054848.5 WD* 04 11 45.8958008181 -05 48 48.520049259           DZ 7 0
20 EGGR 45 WD* 05 55 09.5304147671 -04 10 07.066181242   15.49 14.45 13.994 13.538 DZ11 109 0
21 SDSS J073835.97+384438.2 WD* 07 38 35.9788053777 +38 44 38.199715234           DZ 7 0
22 * alf CMi B WD* 07 39 17.8800 +05 13 26.800   10.7 10.92     DQZ 142 0
23 LAWD 25 WD* 07 40 20.7887176053 -17 24 49.155097204   13.36 13.061 12.886 12.70 DZQA6 185 0
24 SDSS J074743.56+400110.1 WD* 07 47 43.5585931523 +40 01 10.029099135           DZ 8 0
25 SDSS J074751.39+373217.0 WD* 07 47 51.3904058787 +37 32 16.991690703           DZ 7 0
26 SDSS J074821.86+350648.7 WD* 07 48 21.8738644245 +35 06 48.674254489           DZ 7 0
27 SDSS J074942.87+312424.6 ** 07 49 42.8761155830 +31 24 24.700465840           DZ+M 7 0
28 SDSS J074958.26+434306.0 WD* 07 49 58.2637415795 +43 43 06.072905994           DZ 7 0
29 SDSS J075846.91+322523.3 WD* 07 58 46.9076898763 +32 25 23.397859676           DC 5 0
30 SDSS J080211.42+301256.7 ** 08 02 11.4276243793 +30 12 56.907786576           DZ+M: 5 0
31 SDSS J080331.46+450257.8 WD* 08 03 31.4617365681 +45 02 57.637435365           DZAH: 7 0
32 EGGR 346 WD* 08 05 37.6487231197 +38 32 12.775978266   15.62   15.6   DZ5 45 0
33 LP 257-28 WD* 08 05 57.6708030878 +38 33 44.664072227   17.2   16.2   DC9 26 0
34 SDSS J080602.91+374720.6 WD* 08 06 02.9241574041 +37 47 20.768902186           DZ 5 0
35 SDSS J080615.26+364018.1 ** 08 06 15.2609663891 +36 40 18.104697969           DZ+M: 5 0
36 SDSS J082720.59+330437.9 ** 08 27 20.5899754325 +33 04 38.091965395           DZ+M: 5 0
37 SDSS J082927.85+075911.4 WD* 08 29 27.8757837459 +07 59 11.501939541           DZ 5 0
38 LSPM J0834+4641 WD* 08 34 34.6668076064 +46 41 30.717799398   18.8   18.9   DZ 9 0
39 SDSS J083556.32+090619.4 WD* 08 35 56.3122438151 +09 06 19.625725823           DZ 5 0
40 SDSS J084200.24+362540.0 WD* 08 42 00.2454754888 +36 25 40.112560410           DZA 7 0
41 SDSS J084502.70+411547.6 ** 08 45 02.7213455106 +41 15 47.591033608           DZ+M 5 0
42 SDSS J084525.00+535208.8 WD* 08 45 25.0005218281 +53 52 08.774755743           DZ 7 0
43 SDSS J084709.10+450734.7 ** 08 47 09.1257244323 +45 07 34.940529409           DZ+M 5 0
44 SDSS J084828.00+521422.5 WD* 08 48 28.0083286042 +52 14 22.371848178           DZ 9 0
45 SDSS J084849.42+354857.8 WD* 08 48 49.4313807080 +35 48 58.073238046           DZ 8 0
46 SDSS J084857.88+002834.9 WD* 08 48 57.8776588842 +00 28 34.890379840           DB 9 0
47 SDSS J084906.69+071030.0 WD* 08 49 06.6904617937 +07 10 30.043682122           DZ 3 0
48 SDSS J084911.86+403649.7 WD* 08 49 11.8733722609 +40 36 49.748968477           DZ 6 0
49 SDSS J085141.72+053852.1 ** 08 51 41.7281334099 +05 38 52.114757648           DZ+M: 5 0
50 SDSS J090517.71+013307.6 WD* 09 05 17.7125315457 +01 33 07.603386228           DZ 7 0
51 SDSS J090556.22+523533.1 WD* 09 05 56.2185740953 +52 35 33.030071626           DZ 7 0
52 SDSS J091643.07+010531.5 WD* 09 16 43.0839734017 +01 05 31.282730129           DZ 6 0
53 SDSS J092801.78+612434.1 WD* 09 28 01.7891719376 +61 24 34.073127481           DZ 6 0
54 SDSS J093210.54+485601.7 ** 09 32 10.5536796791 +48 56 01.707086760           DZ+M: 5 0
55 SDSS J093423.17+082225.3 WD* 09 34 23.1923378610 +08 22 25.435632097           DZ 6 0
56 SDSS J093545.44+003750.8 WD* 09 35 45.4489222514 +00 37 50.897907032           DZ 5 0
57 SDSS J093704.99+364647.1 WD* 09 37 05.0098992796 +36 46 47.099557325           DZA 5 0
58 SDSS J093942.30+555048.7 WD* 09 39 42.3156530546 +55 50 48.719143862           DZA 13 1
59 SDSS J094148.75+502214.5 WD* 09 41 48.7643284370 +50 22 14.608198891           DZ 5 0
60 SDSS J094206.21+575556.0 WD* 09 42 06.2138412265 +57 55 55.852679572   18.4   19.1   DZ 8 1
61 SDSS J094210.50+074354.8 WD* 09 42 10.5115233554 +07 43 54.790370189           DZ 6 0
62 SDSS J094415.33+393943.0 WD* 09 44 15.3373954112 +39 39 43.028065074           DZ 5 0
63 SDSS J094451.60+440856.7 WD* 09 44 51.6008140858 +44 08 56.708513643           DZ 6 1
64 SDSS J094530.20+084624.8 WD* 09 45 30.2125708991 +08 46 24.809497424           DZ 6 0
65 SDSS J094743.09+423841.3 ** 09 47 43.1022570909 +42 38 41.377286461           DZ+M 5 0
66 SDSS J095119.85+403322.4 WD* 09 51 19.8682189645 +40 33 22.565578086           DZ 10 1
67 SDSS J095435.85+563518.1 WD* 09 54 35.8588938238 +56 35 18.103385469           DZ 6 1
68 SDSS J095645.15+591240.6 WD* 09 56 45.1474931202 +59 12 40.639265026           DZA 16 0
69 SDSS J100237.36+031325.6 WD* 10 02 37.3633120299 +03 13 25.600725267           DZ 6 0
70 SDSS J100406.64+423151.3 ** 10 04 06.6520767210 +42 31 51.474115379           DZ+M 5 0
71 SDSS J100421.25+045117.2 WD* 10 04 21.2535390179 +04 51 17.268564726           DZ 5 0
72 WD 1005+030 WD* 10 08 23.7464927031 +02 48 40.114574286           DZ 9 0
73 SDSS J101007.84+394852.2 WD* 10 10 07.8508387005 +39 48 52.322288496           DZ 5 0
74 SDSS J101558.21+414131.7 WD* 10 15 58.2200052572 +41 41 31.732478190           DZ 6 0
75 SDSS J101805.16+034435.6 WD* 10 18 05.1778717673 +03 44 35.646854777           DZ 5 0
76 SDSS J103126.19+120340.4 WD* 10 31 26.1973969021 +12 03 40.520727901           DZ 6 0
77 SDSS J103300.10+624747.9 WD* 10 33 00.1289253587 +62 47 47.887829292           DZ 7 0
78 SDSS J103651.09+483754.0 WD* 10 36 51.1031505944 +48 37 54.098563413   18.8   18.9   DB/DBZ 6 0
79 SDSS J103809.19-003622.5 WD* 10 38 09.18336 -00 36 22.3524   17.3   16.7   DZ 15 0
80 LP 168-8 WD* 10 39 41.8981128159 +46 12 24.517839506   19.5   19.0   DZ 10 0
81 SDSS J104511.21+625442.3 ** 10 45 11.2222366562 +62 54 42.220302533           DZ+M: 5 0
82 LSPM J1049+5154 WD* 10 49 11.5384905794 +51 54 23.819216874   19.2   17.9   DZ 9 0
83 SDSS J104915.06-000706.2 WD* 10 49 15.0635225341 -00 07 06.254762127   19.12       DZA 12 0
84 SDSS J105221.56+065915.4 WD* 10 52 21.5641340592 +06 59 15.451302266           DZ 5 0
85 SDSS J105601.50+012824.8 WD* 10 56 01.5072016130 +01 28 24.899074551           DZ 7 0
86 SDSS J105616.90-000449.4 ** 10 56 16.8770097464 -00 04 49.553560252   19.77       DZ+M: 9 0
87 LP 93-176 ** 10 56 41.7294450169 +57 14 49.102059629           DZ+M 10 0
88 SDSS J105853.70+604136.8 ** 10 58 53.7106142358 +60 41 36.871149429           DZ+M: 5 0
89 SDSS J110438.38+071129.8 WD* 11 04 38.3912281670 +07 11 29.927382673           DB/DBZ 8 0
90 SDSS J111215.06+070052.4 ** 11 12 15.0594679877 +07 00 52.572053235           DZ+M: 7 0
91 SDSS J112258.34+504146.7 WD* 11 22 58.3486684752 +50 41 46.740897324           DZ 8 0
92 SDSS J112617.16+524155.1 WD* 11 26 17.1790940928 +52 41 55.123498907           DZ 6 0
93 SDSS J112956.98-015229.6 WD* 11 29 56.9886000194 -01 52 29.623616719   19.40       DZA 7 0
94 SDSS J113001.61+103614.8 WD* 11 30 01.6102586705 +10 36 14.949671087           DZ 7 0
95 LSPM J1137+0343 WD* 11 37 11.2983381336 +03 43 24.917365820   17.8   17.8   DZ 9 0
96 SDSS J114054.87+532827.4 ** 11 40 54.8879632372 +53 28 27.333599738           DZ+M: 5 0
97 LSPM J1147+4928 ** 11 47 12.2342116798 +49 28 01.067236285   19.2   18.4   DZ+M 8 0
98 CSO 1241 WD* 11 55 47.4388168663 +43 27 51.397593826   17.9   18.1   DZ 7 0
99 SDSS J121218.68+540938.7 WD* 12 12 18.6982689005 +54 09 38.680494609           DZ 6 0
100 SDSS J121837.12+002304.0 WD* 12 18 37.1190291626 +00 23 03.866295384           DZ 8 1
101 SDSS J122204.47+634354.7 ** 12 22 04.5076470651 +63 43 54.798808233           DZ+M 6 0
102 SDSS J122733.45+633029.5 WD* 12 27 33.4546013929 +63 30 29.443719328           DZ 10 1
103 SDSS J122929.04+425414.4 ** 12 29 29.0411079636 +42 54 14.477044710           DZ+M 5 0
104 SDSS J122953.17+512925.2 WD* 12 29 53.1790737933 +51 29 25.213358368           DZ 5 0
105 WD 1232-032 WD* 12 34 55.9563053417 -03 30 47.146021611           DZ 9 0
106 2QZ J124006.4-003702 WD* 12 40 06.3538889413 -00 37 00.950134750   18.53       DZ 13 0
107 LP 616-31 WD* 12 54 13.7878109607 -02 36 08.532820718           DZ 13 0
108 SDSS J130746.34+030742.0 WD* 13 07 46.3401992682 +03 07 41.958120383           DZ 8 0
109 PB 85 WD* 13 09 05.2500876826 +49 13 59.857470832   17.5       DZ 9 0
110 LB 2597 WD* 13 13 37.0307656805 +57 38 01.617370458   16.7   16.8   DZ 20 0
111 LP 797-33 WD* 13 16 19.5743319382 -20 07 32.058192492   18.09 17.14     DC9 17 0
112 SDSS J132506.96+652132.2 WD* 13 25 06.9470574693 +65 21 32.161175842           DAZBH: 8 0
113 G 165-7 WD* 13 30 59.4185219799 +30 29 53.651634272   16.73 16.04 15.74 15.60 DZ7 66 0
114 LBQS 1335-0115 WD* 13 38 24.9838171701 -01 30 17.027370463           DZ 8 0
115 LP 911-74 WD* 13 41 25.8642038436 -31 24 49.800381669           DZ 10 0
116 2QZ J134144.0-011239 WD* 13 41 44.0995632623 -01 12 38.321906822   19.78       DZ 11 0
117 SDSS J134226.93+052248.6 WD* 13 42 26.9339371989 +05 22 48.657683318           DZ 7 0
118 SDSS J134459.35+650512.5 WD* 13 44 59.3528707038 +65 05 12.531871230           DZ 7 0
119 PB 803 WD* 13 51 18.4062470790 +42 53 16.903546752   17.6   16.4   DZ 14 0
120 SDSS J135137.07+613607.0 WD* 13 51 37.0692381756 +61 36 07.163561518           DC 6 0
121 SDSS J135637.78+404703.4 WD* 13 56 37.8048888329 +40 47 03.457145680           DZ 6 0
122 SDSS J140316.91-002450.0 WD* 14 03 16.9078939216 -00 24 49.906803252           DZ 6 1
123 2QZ J140445.1-023238 WD* 14 04 45.1126413752 -02 32 37.275067825   19.47       DZ 9 0
124 SDSS J141426.55-011354.7 WD* 14 14 26.5458380727 -01 13 54.631020810           DZ 10 0
125 SDSS J142516.43-005048.7 WD* 14 25 16.4266833816 -00 50 48.825657080           DZ 12 0
126 SDSS J142931.18+583927.9 WD* 14 29 31.1943287723 +58 39 27.927462991           DZ 5 0
127 SDSS J143235.82+035423.3 WD* 14 32 35.8199059828 +03 54 23.216561568           DZBA 8 0
128 LP 620-50 WD* 14 40 22.52424 -02 32 22.2324     18.49     DZ 9 0
129 SDSS J144453.66+574147.3 ** 14 44 53.6859705074 +57 41 47.339546665           DZ+M: 5 0
130 SDSS J144516.24-020849.6 ** 14 45 16.2385186700 -02 08 49.575102280   19.294   18.588   DZ+M: 8 0
131 SDSS J151054.85+381450.2 WD* 15 10 54.8572150366 +38 14 50.227300074           DZ 4 0
132 SDSS J151441.87+501209.7 ** 15 14 41.8762136294 +50 12 09.835290412           DZ+M 5 0
133 SDSS J153129.26+424015.7 WD* 15 31 29.2762156502 +42 40 15.773165482           DZ 8 0
134 SDSS J154025.17+514921.5 ** 15 40 25.1773661497 +51 49 21.762674187           DZ+M: 5 0
135 SDSS J154540.21+492145.1 ** 15 45 40.2146875154 +49 21 45.277141885           DZ+M: 5 0
136 SDSS J154623.07+392723.6 WD* 15 46 23.0737984531 +39 27 23.604187731           DZ 4 0
137 SDSS J154953.26+023929.7 WD* 15 49 53.2863052515 +02 39 29.666295278           DZ 6 0
138 SDSS J155852.59+031242.9 WD* 15 58 52.5972132717 +03 12 42.940537557           DZ 7 0
139 SDSS J161801.33+445220.7 WD* 16 18 01.3380552340 +44 52 20.743533536           DZ 5 0
140 Ross 640 WD* 16 28 25.0030292072 +36 46 15.849157470   14.01   13.9   DZ6 178 0
141 SDSS J164026.65+315453.9 WD* 16 40 26.6536985889 +31 54 53.732395685           DZ 6 0
142 SDSS J165741.58+373824.2 ** 16 57 41.5943037139 +37 38 24.181780469           DZ+M: 5 0
143 EGGR 494 WD* 17 08 07.9651561007 +02 57 37.081611590   15.65   14.5   DZ7 54 0
144 SDSS J171139.82+220152.9 WD* 17 11 39.8261943084 +22 01 52.937664516           DZ 3 0
145 SDSS J171436.43+550112.4 WD* 17 14 36.4204277456 +55 01 12.353029162           DZ 6 0
146 SDSS J171513.64+280403.8 WD* 17 15 13.6403136704 +28 04 03.864599770           DZ 6 0
147 SDSS J171900.63+562350.5 WD* 17 19 00.6313184586 +56 23 50.512127846           DZ 8 0
148 SDSS J205059.11-011021.9 WD* 20 50 59.1149576912 -01 10 21.937051169           DZ 4 0
149 SDSS J210303.47-010842.5 WD* 21 03 03.4807064373 -01 08 42.369513750           DZ 3 0
150 SDSS J210733.93-005557.7 WD* 21 07 33.9177311469 -00 55 57.671174742           DZ 9 1
151 SDSS J212424.69-011452.5 ** 21 24 24.7025271592 -01 14 52.444087065           DZ+M: 8 0
152 SDSS J222802.05+120733.3 WD* 22 28 02.0564841287 +12 07 33.383950801           DZ 13 0
153 SDSS J223222.31+010920.6 WD* 22 32 22.3223709582 +01 09 20.777482355           DZ 6 0
154 PG 2234+034 WD* 22 37 00.1002573031 +03 39 30.997294336   17.1 16.8 16.9   DBA4 8 0
155 SDSS J223841.06+010150.1 WD* 22 38 41.0532422472 +01 01 50.438550131           DZ 5 0
156 EGGR 453 WD* 22 53 53.3851195567 -06 46 54.488931649   17.53 15.66 15.70   DZ13 87 1
157 EGGR 554 WD* 23 15 18.8071668249 -02 09 40.601534867   16.80 16.29     DZ8 44 0
158 SDSS J234245.90-000632.5 WD* 23 42 45.9098099952 -00 06 32.486390754           DZA 5 1
159 Ruiz 292-43 WD* 23 48 16.7658801094 -44 28 11.756228973   18.66 17.87 17.5   DZ 10 0
160 SDSS J235516.60+143136.2 WD* 23 55 16.5836682121 +14 31 36.277147424           DZ 5 0

    Equat.    Gal    SGal    Ecl

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2021.05.16-20:46:30

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