ROXs 12
Binary system of pre-main-sequence stars
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ROXs 12 is a member of a binary system of pre-main-sequence stars. It belongs to the Rho Ophiuchi cloud complex.[7] The surface temperature of the primary star is 3900±100 K.[5] ROXs 12 is much younger than the Sun with an age of 7.6+4.1
−2.5 million years.[7]
ROXs 12 (bright star at the center) and ROX 12b (object at the top) Credit: ESO VLT MUSE; Claudio Caceres et al. & Meli_thev | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Scorpius[1] |
| Right ascension | 16h 26m 28.0400s[2] |
| Declination | −25° 26′ 47.717″[2] |
| Apparent magnitude (V) | 14.29[3] |
| Characteristics | |
| Evolutionary stage | pre-main-sequence[4] |
| Spectral type | M0.0e[4] |
| Astrometry | |
| Radial velocity (Rv) | −9.0±5.4[2] km/s |
| Proper motion (μ) | RA: −6.858[2] mas/yr Dec.: −24.815[2] mas/yr |
| Parallax (π) | 7.2170±0.0172 mas[2] |
| Distance | 452 ± 1 ly (138.6 ± 0.3 pc) |
| Details[5] | |
| ROXs 12 | |
| Mass | 0.65+0.05 −0.09 M☉ |
| Radius | 1.14±0.07 R☉ |
| Temperature | 3900±100 K |
| Rotation | 9.1±0.4 d |
| Age | 7.6+4.1 −2.5 Myr |
| Other designations | |
| WDS J16265-2527A, 2MASS J16262803-2526477, DENIS J162628.0-252647[6] | |
| Database references | |
| SIMBAD | ROXs 12 |
| ROXs 12b | |
A multiplicity survey detected a stellar companion to ROXs 12 in 2017, named 2MASS J16262774–2527247,[8] at a projected separation of 5100 AU.[9] 2MASS J16262774–2527247 is also a pre-main-sequece star with a mass of 0.8 M☉.[8]
Planetary system
In 2005, one planet was discovered on a wide orbit by direct imaging,[10] was confirmed in 2013 and named ROXs 12 b.[7] The planet's measured temperature is 3100+400
−500 K.[9] The spectroscopy of the planet was obtained with Keck and Gemini, revealing a low surface gravity and a spectral type of L0±2, making this object either a late M-dwarf or an early L-dwarf. The signs of low gravity includes weak alkali absorption and a triangular H-band spectrum shape. The study also found misalignment between the line-of-sight inclinations of ROXs 12A and 2MASS J16262774–2527247. ROXs 12 B is also likely misaligned with its host star. This was interpreted as either formation similar to fragmenting binary stars or ROXs 12B formed in an equatorial disk that was torqued by 2MASS J16262774–2527247. This study also found strong signs of accretion around 2MASS J16262774–2527247 from emission lines, including strong H-alpha emission.[5]
The primary star is surrounded by a protoplanetary disk, although it is not very massive, being less than 4 MJ.[7] The secondary star also has a protoplanetary disk, and it is much more massive, equal to 10-1.07+0.49
−0.87 M☉. The disk is inclined to the equatorial plane of the star.[8]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| Protoplanetary or debris disk | ? AU | — | — | |||
| b | 16±4 MJ | 210±20 | — | ~0 | — | 2.20±0.35[11] RJ |
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| Protoplanetary disk | 4.1–25.8[8] AU | — | — | |||