HD 203030B: An unusually cool young substellar companion near the L/T transition

被引：130

作者：

Metchev, Stanimir A. ^{[1
]}

Hillenbrand, Lynne A.

机构：

[1] Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA

[2] CALTECH, Div Phys Math & Astron, Pasadena, CA 91125 USA

来源：

ASTROPHYSICAL JOURNAL | 2006年 / 651卷 / 02期

关键词：

binaries : general; instrumentation : adaptive optics; stars : individual (HD 203030); stars : low-mass; brown dwarfs;

D O I：

10.1086/507836

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present the discovery of a brown dwarf companion to the star HD 203030: a G8 V Solar analog with an estimated age between 130 and 400 Myr old G8 V. Separated by 11."9 (487 AU in projection) from its host star, HD 203030B has an estimated mass of 0: 023(-0.011)(+0.008) M-circle dot. The K-band spectral type of L7.5 +/- 0.5 places HD203030B near the critical L/T transition in brown dwarfs, which is characterized by the rapid disappearance of dust in substellar photospheres. From a comparative analysis with well-characterized field L/T transition dwarfs, we find that, despite its young age, HD 203030B has a bolometric luminosity similar to the > 1 Gyr old field dwarfs. Adopting a radius from current models of substellar evolution, we hence obtain that the effective temperature of HD203030B is only 1206(-116)(+74) K, markedly lower than the approximate to 1440 K effective temperatures of field L/T transition dwarfs. The temperature discrepancy can be resolved if either (1) the ages of field brown dwarfs have been overestimated by a factor of approximate to 1.5, leading to underestimated radii, or (2) the lower effective temperature of HD 203030B is related to its young age, implying that the effective temperature at the L/T transition is gravity dependent.

引用

页码：1166 / 1176

页数：11

共 90 条

[21]

Donahue R. A., 1993, THESIS NEW MEXICO ST

[22]

DRLLLING JS, 2000, ALLENS ASTROPHYSICAL, P382

[23] LITHIUM ABUNDANCE AND AGE SPREAD IN THE PLEIADES [J].

DUNCAN, DK ;

JONES, BF .

ASTROPHYSICAL JOURNAL, 1983, 271 (02) :663-671

[24]

DUQUENNOY A, 1991, ASTRON ASTROPHYS, V248, P485

[25] Radii and effective temperatures for K and M giants and supergiants [J].

Dyck, HM ;

Benson, JA ;

vanBelle, GT ;

Ridgway, ST .

ASTRONOMICAL JOURNAL, 1996, 111 (04) :1705-1712

[26] COLORS LUMINOSITIES + MOTIONS OF NEARER G-TYPE STARS [J].

EGGEN, OJ .

ASTRONOMICAL JOURNAL, 1964, 69 (08) :570-&

[27] Photometric variability at the L/T dwarf boundary [J].

Enoch, ML ;

Brown, ME ;

Burgasser, AJ .

ASTRONOMICAL JOURNAL, 2003, 126 (02) :1006-1016

[28] THE EINSTEIN EXTENDED MEDIUM SENSITIVITY SURVEY 2ND EPOCH - RESULTS FOR THE STARS [J].

FLEMING, TA ;

MOLENDI, S ;

MACCACARO, T ;

WOLTER, A .

ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1995, 99 (02) :701-711

[29] Toward spectral classification of L and T dwarfs: Infrared and optical spectroscopy and analysis [J].

Geballe, TR ;

Knapp, GR ;

Leggett, SK ;

Fan, X ;

Golimowski, DA ;

Anderson, S ;

Brinkmann, J ;

Csabai, I ;

Gunn, JE ;

Hawley, SL ;

Hennessy, G ;

Henry, TJ ;

Hill, GJ ;

Hindsley, RB ;

Ivezic, Z ;

Lupton, RH ;

McDaniel, A ;

Munn, JA ;

Narayanan, VK ;

Peng, E ;

Pier, JR ;

Rockosi, CM ;

Schneider, DP ;

Smith, JA ;

Strauss, MA ;

Tsvetanov, ZI ;

Uomoto, A ;

York, DG ;

Zheng, W .

ASTROPHYSICAL JOURNAL, 2002, 564 (01) :466-481

[30] Hubble Space Telescope observations of binary very low mass stars and brown dwarfs [J].

Gizis, JE ;

Reid, IN ;

Knapp, GR ;

Liebert, J ;

Kirkpatrick, JD ;

Koerner, DW ;

Burgasser, AJ .

ASTRONOMICAL JOURNAL, 2003, 125 (06) :3302-3310

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