2006A&A...460..635C


Query : 2006A&A...460..635C

2006A&A...460..635C - Astronomy and Astrophysics, volume 460, 635-640 (2006/12-3)

Are isolated planetary-mass objects really isolated? A brown dwarf-exoplanet system candidate in the σ Orionis cluster.

CABALLERO J.A., MARTIN E.L., DOBBIE P.D. and BARRADO Y NAVASCUES D.

Abstract (from CDS):

Free-floating planetary-mass objects have masses below the deuterium burning mass limit at about 13 Jupiter masses, and have mostly been found in very young open clusters. Their origin and relationship to stars and brown dwarfs are still a mystery. The recent detection by direct imaging of three giant planets at wide separation (50-250AU) from their primaries has raised the question about the true ``isolation'' of planetary-mass objects in clusters. Our goal was to test the possibility that some free-floating planetary-mass objects could in fact be part of wide planetary systems. We searched in the literature for stellar and brown-dwarf candidates members of the σ Orionis cluster (∼3Ma, ∼360pc) at small angular separations from published candidate planetary-mass objects. We found one candidate planetary system composed of an X-ray source, SE 70, and a planetary-mass object, SOri 68, separated by only 4.6arcsec. In order to assess the cluster membership of the X-ray source, we obtained mid-resolution optical spectroscopy using ISIS on the William Herschel Telescope. We also compiled additional data on the target from available astronomical catalogues. We have found that SE 70 follows the spectrophotometric sequence of the cluster and displays spectroscopic features of youth, such as lithium in absorption and chromospheric Hα emission. The radial velocity is consistent with cluster membership. Hence, SE 70 is very probably a member of the σ Orionis cluster. The projected physical separation between SE 70 and SOri 68 is 1700±300AU at the distance of the cluster. If a common proper motion is confirmed in the near future, the system would be composed of an M5-6 brown dwarf with an estimated mass of ∼45MJup and an L5±2 giant planet with an estimated mass of ∼5MJup. It would be the widest and one of the lowest-mass planetary systems known so far.

Abstract Copyright:

Journal keyword(s): stars: low-mass, brown dwarfs - planetary systems - open clusters and associations: individual: σ Orionis

CDS comments: Note 2 p.639 [BMZ2001] S Ori J053926.8-026614 is a misprint for [BMZ2001] S Ori J053926.8-022614

Simbad objects: 25

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Number of rows : 25
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 LP 944-20 LM* 03 39 35.2523500210 -35 25 43.641996333     18.69 16.39 13.288 M9.5Ve 274 0
2 Ass Ori OB 1b As* 05 34.0 -01 30           ~ 254 0
3 2MASS J05371161-0232087 Y*O 05 37 11.6194325448 -02 32 08.795526792   13.78 12.71 12.59 11.40 K2.0 14 0
4 [BZR99] S Ori 66 BD* 05 37 24.71064 -02 31 52.3308         23.23 L3.5:e 12 0
5 V* V2728 Ori Or* 05 38 25.4373236808 -02 42 41.266014912   20.88 20.33 19.08 17.20 M7 31 0
6 V* V2729 Ori Or* 05 38 25.57752 -02 48 37.0224   21.09 24.40 22.07 19.54 M8.5 31 0
7 2MASS J05383888-0228016 Y*O 05 38 38.8901286864 -02 28 01.718651352 20.95 21.83   18.77 16.99 M5Ve 24 0
8 [BZR99] S Ori 68 BD* 05 38 39.1 -02 28 05         23.77 L5: 24 1
9 NAME sigma Orionis Cluster MGr 05 38 42 -02 36.0           ~ 522 0
10 * sig Ori Y*O 05 38 44.7653828520 -02 36 00.283179888 2.54 3.58 3.79 3.87 4.11 O9.5V 773 0
11 NAME sig Ori IRS 1 * 05 38 44.9 -02 35 57           ~ 15 0
12 2MASS J05384755-0227120 Y*O 05 38 47.5456806504 -02 27 12.033175788 19.62 19.01 17.53 16.00 14.11 M5 15 0
13 [W96] 4771-899 TT* 05 38 48.0364463496 -02 27 14.149731420 16.327 14.47 13.21 12.41 11.54 K7e 25 0
14 HD 37525 Y*O 05 39 01.4927799048 -02 38 56.364214344   7.98 8.06   8.210 B5V 71 1
15 Mayrit 425070 Y*O 05 39 11.4017533992 -02 33 32.831052984 21.773 21.52 19.94 18.32 16.43 M5e 26 0
16 [BMZ2001] S Ori J053926.8-022614 * 05 39 26.7727217568 -02 26 14.336925828   21.76     18.26 ~ 9 0
17 HD 44627 Ro* 06 19 12.9130449912 -58 03 15.527294208   10.01 9.205   8.185 K1V(e) 155 1
18 HD 289002 * 06 45 13.3725491952 +02 08 14.685250596 10.06 10.62 10.44     B1 240 0
19 * rho01 Cnc d Pl 08 52 35.8113282132 +28 19 50.956901366           ~ 142 1
20 NAME TW Hya Association As* 11 01.9 -34 42           ~ 884 0
21 TWA 27 LM* 12 07 33.4675524840 -39 32 54.016625184     19.95 17.99 15.88 M8IVe 322 0
22 TWA 27B BD* 12 07 33.50 -39 32 54.4           L3 261 0
23 CD-35 10525 Or* 15 49 12.1053805848 -35 39 05.058139788 12.19 12.76 11.66 11.15   K7Ve 270 0
24 NAME Oph 11 ** 16 22 25.21392 -24 05 13.9488       19.4 18.98 M9+M9.5 43 0
25 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3334 1

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2022.05.21-15:58:29

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