A flaring L5 dwarf:: The nature of Hα emission in very low mass (sub)stellar objects

被引:107
作者
Liebert, J
Kirkpatrick, JD
Cruz, KL
Reid, IN
Burgasser, A
Tinney, CG
Gizis, JE
机构
[1] Univ Arizona, Steward Observ, Tucson, AZ 85721 USA
[2] CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA
[3] Univ Penn, Dept Phys & Astron, Philadelphia, PA 19104 USA
[4] Space Telescope Sci Inst, Baltimore, MD 21218 USA
[5] Univ Calif Los Angeles, Dept Astron & Astrophys, Los Angeles, CA 90095 USA
[6] Anglo Australian Observ, Epping, NSW 1710, Australia
[7] Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA
关键词
stars : chromospheres; stars : individual (2MASS J01443536-0716142; 2MASSI J1315309-264951; PC; 0025+0447; 2MASSI J1237392+652615); stars : low mass; brown dwarfs;
D O I
10.1086/345514
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Time series spectrophotometry of the L5 dwarf 2MASS J01443536-0716142 showed strong H emission that declined by nearly 75% in four consecutive exposures. The line was not detected in emission on a spectrum obtained 11 months later. This behavior contrasts with that of 2MASSI J1315309-264951, an L5 dwarf that has shown even stronger Halpha emission on four separate occasions. The observational database suggests that L dwarfs can be found in such strong flares only occasionally, with a duty cycle on the order of 1%. In contrast, the few, continuously strong Halpha emitters, including PC 0025+ 0447 and 2MASSI J1237392+ 652615, must either be (1) objects no older than 10-100 Myr with continuously active accretion and/or chromospheres, but which apparently formed in isolation from known young stellar clusters and associations, or (2) objects empowered by a different but unknown mechanism for the Halpha energy.
引用
收藏
页码:343 / 347
页数:5
相关论文
共 45 条
[31]   Discovery of a very cool object with extraordinarily strong Hα emission [J].
Navascués, DBY ;
Osorio, MRZ ;
Martín, EL ;
Béjar, VJS ;
Rebolo, R ;
Mundt, R .
ASTRONOMY & ASTROPHYSICS, 2002, 393 (03) :L85-L88
[32]  
Navascués DBY, 2001, ASTROPHYS J SUPPL S, V134, P103, DOI 10.1086/320359
[33]   Optical spectroscopy of isolated planetary mass objects in the σ Orionis cluster [J].
Navascués, DBY ;
Osorio, MRZ ;
Béjar, VJS ;
Rebolo, R ;
Martín, EL ;
Mundt, R ;
Bailer-Jones, CAL .
ASTRONOMY & ASTROPHYSICS, 2001, 377 (02) :L9-L13
[34]   THE KECK LOW-RESOLUTION IMAGING SPECTROMETER [J].
OKE, JB ;
COHEN, JG ;
CARR, M ;
CROMER, J ;
DINGIZIAN, A ;
HARRIS, FH ;
LABRECQUE, S ;
LUCINIO, R ;
SCHAAL, W ;
EPPS, H ;
MILLER, J .
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC, 1995, 107 (710) :375-385
[35]   Activity at the deuterium-burning mass limit in Orion [J].
Osorio, MRZ ;
Béjar, VJS ;
Martín, EL ;
Navascués, DBY ;
Rebolo, R .
ASTROPHYSICAL JOURNAL, 2002, 569 (02) :L99-L102
[36]   Lithium and Hα in stars and brown dwarfs of σ Orionis [J].
Osorio, MRZ ;
Béjar, VJS ;
Pavlenko, Y ;
Rebolo, R ;
Prieto, CA ;
Martín, EL ;
López, RJG .
ASTRONOMY & ASTROPHYSICS, 2002, 384 (03) :937-953
[37]   New neighbours:: IV.: 30 DENIS late-M dwarfs between 15 and 30 parsecs [J].
Phan-Bao, N ;
Guibert, J ;
Crifo, F ;
Delfosse, X ;
Forveille, T ;
Borsenberger, J ;
Epchtein, N ;
Fouqué, P ;
Simon, G .
ASTRONOMY & ASTROPHYSICS, 2001, 380 (02) :590-598
[38]   BRI 0021-0214: Another surprise at the bottom of the main sequence [J].
Reid, IN ;
Kirkpatrick, JD ;
Gizis, JE ;
Liebert, J .
ASTROPHYSICAL JOURNAL, 1999, 527 (02) :L105-L107
[39]   Near-infrared spectral classification of late M and L dwarfs [J].
Reid, IN ;
Burgasser, AJ ;
Cruz, KL ;
Kirkpatrick, JD ;
Gizis, JE .
ASTRONOMICAL JOURNAL, 2001, 121 (03) :1710-1721
[40]   Chandra detection of an X-ray flare from the brown dwarf LP 944-20 [J].
Rutledge, RE ;
Basri, G ;
Martín, EL ;
Bildsten, L .
ASTROPHYSICAL JOURNAL, 2000, 538 (02) :L141-L144