2001ApJ...563..361I


C.D.S. - SIMBAD4 rel 1.7 - 2021.01.22CET21:25:01

2001ApJ...563..361I - Astrophys. J., 563, 361-366 (2001/December-2)

X-ray detection from bona fide and candidate brown dwarfs in the ρ Ophiuchi cloud with Chandra.

IMANISHI K., TSUJIMOTO M. and KOYAMA K.

Abstract (from CDS):

We present results of an X-ray search from bona fide and candidate brown dwarfs in the ρ Ophiuchi cloud cores with the Chandra X-ray Observatory. The selected areas are two fields near the cloud center and are observed with the ACIS-I array of a 17'x17' size and a ∼100 ks exposure. Among 18 bona fide and candidate brown dwarfs listed by the infrared spectroscopy, we find X-ray emission from seven sources above 99.9% confidence level. Therefore, ∼40% of the infrared-selected brown dwarfs in this cloud emit X-rays. For the brightest four sources, the X-ray spectra are made and are fitted with a thin-thermal plasma model of a temperature 1-2.5 keV. The X-rays are also time variable with rapid flares from two of the brown dwarfs. Assuming 2 keV temperature and using the empirical relation of AV versus NH, we estimate the X-ray luminosity or its upper limit of the other faint or non-X-ray sources. The X-ray luminosity (LX) of the X-ray-detected sources is in the range of 0.3-90x1028 ergs.s–1, while the luminosity ratio of X-ray to bolometric (LX/Lbol) is 10–5-10–3, similar to those of low-mass pre-main-sequence and dMe stars. All these results suggest that the X-ray origin of brown dwarfs is the same as low-mass stars; strong magnetic activity at the stellar surface.

Abstract Copyright:

Journal keyword(s): ISM: individual (ρ Ophiuchi Cloud) - Stars: Low-Mass, Brown Dwarfs - X-Rays: Stars

Errata: erratum vol. 579, p. 921 (2002)

CDS comments: CRBR 31 = CRBR 2322.3-1143, crbr 67 = CRBR 2412.9-2447

Simbad objects: 27

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Number of rows : 27

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 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3614 0
2 NAME Chamaeleon Region SFR 11 55 -78.0           ~ 704 0
3 CRBR 2317.3-1925 Y*O 16 26 18.82056 -24 26 10.5216           M7 41 0
4 CRBR 2317.5-1729 Y*O 16 26 18.98232 -24 24 14.2596           ~ 41 0
5 [GY92] 5 Y*O 16 26 21.5389368381 -24 26 01.000528521       18.30 15.80 M7 62 1
6 [GY92] 10 Y*O 16 26 22.18584 -24 23 52.3572           M8.5 29 0
7 [RR90] Oph 2320.8-1721 Y*O 16 26 22.26912 -24 24 07.0632           M8 66 0
8 CRBR 2322.3-1143 Y*O 16 26 23.81424 -24 18 29.0016           M6.7 23 0
9 [GY92] 31 Y*O 16 26 25.23384 -24 23 23.9208           M5.5 25 1
10 NAME rho Oph A Cloud MoC 16 26 26.4 -24 22 33           ~ 244 1
11 VSSG 29 Y*O 16 26 27.8166288668 -24 26 41.866584968         17.85 M5 37 1
12 [GY92] 59 TT* 16 26 31.3549579882 -24 25 30.696367606         18.90 M3.75 20 1
13 [GY92] 64 Y*O 16 26 32.52576 -24 26 35.4480           M8 21 0
14 [GY92] 84 Y*O 16 26 38.80368 -24 23 22.7328           M6 20 0
15 [RR90] Oph 2349.8-2601 Y*O 16 26 51.2908889493 -24 32 42.017741452           M8.5 50 0
16 NAME rho Oph C Cloud MoC 16 26 53.1 -24 32 31           ~ 57 0
17 BBRCG 16 TT* 16 26 56.91984 -24 28 37.0740           M2.5 16 0
18 NAME rho Oph E MoC 16 27 02.0 -24 38 31           ~ 56 0
19 VSSG 31 Y*O 16 27 04.10688 -24 28 29.9136           ~ 59 1
20 BBRCG 21 Y*O 16 27 05.97624 -24 28 36.3252           M7 37 0
21 BBRCG 26 Y*O 16 27 10.03536 -24 29 13.3008           ~ 24 0
22 NAME rho Oph B Cloud MoC 16 27 11 -24 28.5           ~ 67 1
23 [RR90] Oph 2412.9-2447 Y*O 16 27 14.34048 -24 31 31.9260           M7.75 10 0
24 NAME rho Oph F MoC 16 27 37.3 -24 42 28           ~ 58 0
25 [GY92] 310 Y*O 16 27 38.6280925403 -24 38 39.230714152         17.40 M8 62 0
26 [GY92] 326 TT* 16 27 42.7019471651 -24 38 50.620859523         17.30 M2 39 0
27 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3114 1

    Equat.    Gal    SGal    Ecl

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