BD+29 5007

BD+29 5007 is a K-type star, located 77 light-years away in the constellation Pegasus.^[3] It has a large-separation companion that was identified in 2016.^[6] The pair was identified to be a possible member of the 45+15
−5 million years old Argus association (see IC 2391),^[7] though this is disputed.^[8]

BD+29 5007

BD+29 5007 and its companion
Observation data Epoch J2000      Equinox J2000
Constellation	Pegasus
Right ascension	23h 50m 27.862s[1]
Declination	+30° 21′ 11.73″[1]
Apparent magnitude (V)	9.35[2]
Characteristics
Spectral type	K5V[3]
B−V color index	1.226±0.024[2]
Astrometry
Radial velocity (Rv)	−3.77±0.19[2] km/s
Proper motion (μ)	RA: 255.381 mas/yr Dec.: 10.628 mas/yr
Parallax (π)	42.2919±0.0166 mas[1]
Distance	77.12 ± 0.03 ly (23.645 ± 0.009 pc)
Absolute magnitude (MV)	7.46[2]
Details[4]
Mass	0.671±0.021 M☉
Radius	0.703±0.021 R☉
Luminosity	0.160±0.004 L☉
Temperature	4,327±144 K
Other designations
BD+29°5007, GJ 9841, HIP 117559, SAO 73544, PPM 89170[5]
Database references
SIMBAD	data

Properties

The star has a mass of 0.671±0.021 M_☉, a radius of 0.703±0.021 R_☉ and a temperature of 4327±144 Kelvin.^[4] It has a spectral type of K5V.^[3]

Companion

The companion is 2MASS J23512200+3010540 (short: 2MASS J2351+3010) that was discovered in 2010^[9] and first identified as a possibly young low-mass object in 2014 by the BANYAN II survey. The authors find a L5.5 dwarf with red near-infrared colors. If it is a member of Argus, it should have a mass of 9−11 M_J, according to the authors.^[10] However, the BANYAN VII survey in 2015 revised the status of 2MASS J2351+3010 to a field object, i.e. not a member of any stellar cluster or association.^[8] This is also suggested by measured surface gravity of 2MASS J2351+3010, consistent with that of a field object.^[11][12] This would mean that the companion is too massive to have a planetary mass (i.e. its mass is larger than 13 M_J).^[12]

In 2016 it was identified as a possible companion to BD+29 5007.^[6] In 2024 it was again identified as an Argus member with a mass of 11.9+0.4
−0.2 M_J. The same authors calculate that this system has a probability of 1.71% to be a false-positive match.^[7][3] The companion is separated by 935 arcseconds, which translates into 22,100 astronomical units at this distance.^[3] This high separation is larger than the 12,000 AU projected separation of Gliese 900 b,^[13] currently the planetary-mass object with the longest known orbit, and is similar to brown dwarfs such as UCAC4 328-061594.^[14]

See also

• List of exoplanet extremes
• COCONUTS-2b