PRECISION PHOTOMETRIC MONITORING OF VERY LOW MASS σ ORIONIS CLUSTER MEMBERS: VARIABILITY AND ROTATION AT A FEW Myr

被引:78
作者
Cody, Ann Marie [1 ]
Hillenbrand, Lynne A. [1 ]
机构
[1] CALTECH, Dept Astrophys, Pasadena, CA 91125 USA
基金
美国国家科学基金会;
关键词
brown dwarfs; open clusters and associations: individual (sigma Orionis); protoplanetary disks; stars: low-mass; stars: rotation; stars: variables: T Tauri; Herbig Ae/Be; techniques: photometric; MAIN-SEQUENCE STARS; YOUNG BROWN DWARFS; T-TAURI STARS; DISK REGULATION PARADIGM; NEBULA CLUSTER; SPITZER OBSERVATIONS; STELLAR ROTATION; ORI CLUSTER; IMAGE SUBTRACTION; SPECTRAL-ANALYSIS;
D O I
10.1088/0067-0049/191/2/389
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present high-precision photometry on 107 variable low-mass stars and brown dwarfs in the similar to 3 Myr sigma Orionis open cluster. We have carried out I-band photometric monitoring within two fields, encompassing 153 confirmed or candidate members of the low-mass cluster population, from 0.02 to 0.5 M-circle dot. We are sensitive to brightness changes on timescales from 10 minutes to two weeks with amplitudes as low as 0.004 mag, and find variability on these timescales in nearly 70% of cluster members. We identify both periodic and aperiodic modes of variability, as well as semi-periodic rapid fading events that are not accounted for by the standard explanations of rotational modulation of surface features or accretion. We have incorporated both optical and infrared color data to uncover trends in variability with mass and circumstellar disks. While the data confirm that the lowest-mass objects (M < 0.2 M-circle dot) rotate more rapidly than the 0.2-0.5 M-circle dot members, they do not support a direct connection between rotation rate and the presence of a disk. Finally, we speculate on the origin of irregular variability in cluster members with no evidence for disks or accretion.
引用
收藏
页码:389 / 422
页数:34
相关论文
共 96 条
[1]   A method for optimal image subtraction [J].
Alard, C ;
Lupton, RH .
ASTROPHYSICAL JOURNAL, 1998, 503 (01) :325-331
[2]   Accretion dynamics and disk evolution in NGC 2264: a study based on CoRoT photometric observations [J].
Alencar, S. H. P. ;
Teixeira, P. S. ;
Guimaraes, M. M. ;
McGinnis, P. T. ;
Gameiro, J. F. ;
Bouvier, J. ;
Aigrain, S. ;
Flaccomio, E. ;
Favata, F. .
ASTRONOMY & ASTROPHYSICS, 2010, 519
[3]   The irradiated Herbig-Haro jets near σ Orionis [J].
Andrews, SM ;
Reipurth, B ;
Bally, J ;
Heathcote, SR .
ASTROPHYSICAL JOURNAL, 2004, 606 (01) :353-368
[4]   Variability in ultra cool dwarfs: Evidence for the evolution of surface features [J].
Bailer-Jones, CAL ;
Mundt, R .
ASTRONOMY & ASTROPHYSICS, 2001, 367 (01) :218-235
[5]  
Baraffe I, 1998, ASTRON ASTROPHYS, V337, P403
[6]  
Baraffe I., 2002, ASTRON ASTROPHYS, V382, P563
[7]   The Deep Lens Survey transient search. I. Short timescale and astrometric variability [J].
Becker, AC ;
Wittman, DM ;
Boeshaar, PC ;
Clocchiatti, A ;
Dell'Antonio, IP ;
Frail, DA ;
Halpern, J ;
Margoniner, VE ;
Norman, D ;
Tyson, JA ;
Schommer, RA .
ASTROPHYSICAL JOURNAL, 2004, 611 (01) :418-433
[8]   Optical and infrared photometry of new very low-mass stars and brown dwarfs in the σ Orionis cluster [J].
Béjar, VJS ;
Osorio, MRZ ;
Rebolo, R .
ASTRONOMISCHE NACHRICHTEN, 2004, 325 (09) :705-713
[9]   A search for very low mass stars and brown dwarfs in the young σ orionis cluster [J].
Béjar, VJS ;
Osorio, MRZ ;
Rebolo, R .
ASTROPHYSICAL JOURNAL, 1999, 521 (02) :671-681
[10]   The substellar mass function in σ Orionis [J].
Béjar, VJS ;
Martín, EL ;
Osorio, MRZ ;
Rebolo, R ;
Navascués, DBY ;
Bailer-Jones, CAL ;
Mundt, R ;
Baraffe, I ;
Chabrier, C ;
Allard, F .
ASTROPHYSICAL JOURNAL, 2001, 556 (02) :830-836