TY - JOUR
T1 - Discovery of a brown dwarf very close to the sun
T2 - A methane-rich brown dwarf companion to the low-mass star SCR 1845-6357
AU - Biller, B. A.
AU - Kasper, M.
AU - Close, L. M.
AU - Brandner, W.
AU - Kellner, S.
N1 - Funding Information:
B. A. B. is supported by the NASA GSRP grant NNG04GN95H and NASA Origins grant NNG05GL71G. L. M. C. is supported in part by an NSF CAREER award. This research has made use of data products from the Super-COSMOS Sky Surveys at the Wide Field Astronomy Unit of the Institute for Astronomy, University of Edinburgh, and from the Two Micron All Sky Survey, a joint project of the University of Massachusetts and IPAC/Caltech, funded by NASA and the NSF. We thank Sandy Leggett for providing electronic L and T dwarf spectra through her Web site. We thank Ralf-Dieter Scholz for alerting us to the updated parallax for SCR 1845A, and Todd Henry for providing this parallax in advance of publication. We thank John Gizis for refereeing this Letter and for useful suggestions.
PY - 2006/4/20
Y1 - 2006/4/20
N2 - We present VLT/NACO SDI images of the very nearby star SCR 1845-6357 (hereafter SCR 1845). SCR 1845 is a recently discovered M8.5 star just 3.85 pc from the Sun. Using the capabilities of the unique SDI device, we discovered a substellar companion to SCR 1845 at a separation of 4.5 AU (1.″170 ± 0.″003 on the sky) and fainter by 3.57 ± 0.057 mag in the 1.575 μm SDI filter. This substellar companion has an H magnitude of 13.16-0.26+0.31, (absolute H magnitude of 15.30 -0.26+0.31), making it likely the brightest mid-T dwarf known. The Simultaneous Differential Imager (SDI) consists of three narrowband filters placed around the 1.6 μm methane absorption feature characteristic of T dwarfs (Teff < 1200 K). The flux of the substellar companion drops by a factor of 2.7 ± 0.1 between the SDI F1 (1.575 μm) and F3 (1.625 μm) filters, consistent with strong methane absorption in a substellar companion. We estimate a spectral type of T5.5 μ1 for the companion based on the strength of this methane break. The chances that this object is a background T dwarf are vanishingly small - and there is no isolated background T dwarf in this part of the sky, according to 2MASS. Thus, it is a bound companion, hereafter SCR 1845B. For an age range of 100 Myr to 10 Gyr and spectral type range of T4.5-T6.5, we find a mass range of (9-65)MJup for SCR 1845B from the Baraffe et al. "COND" models. SCR 1845AB is the 24th-closest stellar system to the Sun (at 3.85 pc); the only brown dwarf system closer to the Sun is the binary brown dwarf ε Indi Ba-Bb (at 3.626 pc). In addition, this is the first T dwarf companion discovered around a low-mass star.
AB - We present VLT/NACO SDI images of the very nearby star SCR 1845-6357 (hereafter SCR 1845). SCR 1845 is a recently discovered M8.5 star just 3.85 pc from the Sun. Using the capabilities of the unique SDI device, we discovered a substellar companion to SCR 1845 at a separation of 4.5 AU (1.″170 ± 0.″003 on the sky) and fainter by 3.57 ± 0.057 mag in the 1.575 μm SDI filter. This substellar companion has an H magnitude of 13.16-0.26+0.31, (absolute H magnitude of 15.30 -0.26+0.31), making it likely the brightest mid-T dwarf known. The Simultaneous Differential Imager (SDI) consists of three narrowband filters placed around the 1.6 μm methane absorption feature characteristic of T dwarfs (Teff < 1200 K). The flux of the substellar companion drops by a factor of 2.7 ± 0.1 between the SDI F1 (1.575 μm) and F3 (1.625 μm) filters, consistent with strong methane absorption in a substellar companion. We estimate a spectral type of T5.5 μ1 for the companion based on the strength of this methane break. The chances that this object is a background T dwarf are vanishingly small - and there is no isolated background T dwarf in this part of the sky, according to 2MASS. Thus, it is a bound companion, hereafter SCR 1845B. For an age range of 100 Myr to 10 Gyr and spectral type range of T4.5-T6.5, we find a mass range of (9-65)MJup for SCR 1845B from the Baraffe et al. "COND" models. SCR 1845AB is the 24th-closest stellar system to the Sun (at 3.85 pc); the only brown dwarf system closer to the Sun is the binary brown dwarf ε Indi Ba-Bb (at 3.626 pc). In addition, this is the first T dwarf companion discovered around a low-mass star.
KW - Binaries: close
KW - Instrumentation: adaptive optics
KW - Stars: imaging
KW - Stars: low-mass, brown dwarfs
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U2 - 10.1086/504256
DO - 10.1086/504256
M3 - Article
AN - SCOPUS:33745297375
SN - 0004-637X
VL - 641
SP - L141-L144
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2 II
ER -