Mu Pictoris

μ Pictoris, Latinised as Mu Pictoris, is a binary star^[2] system in the southern constellation Pictor. It is bright enough to be dimly visible to the naked eye, having a combined apparent visual magnitude of 5.69.^[6] Based upon an annual parallax shift of 5.4 mas as seen from Earth,^[1] the system is located roughly 610 light years distant from the Sun. As of 2010, the pair have an angular separation of 2.46 arc seconds along a position angle of 221°.^[4]

Mu Pictoris

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Pictor
μ Pic A
Right ascension	06h 31m 58.31011s[1]
Declination	−58° 45′ 13.8114″[1]
Apparent magnitude (V)	5.71[2]
μ Pic B
Right ascension	06h 31m 58.0685s[3]
Declination	−58° 45′ 15.4103″[3]
Apparent magnitude (V)	9.43[2]
Characteristics
Spectral type	B9 Ve[4] or B9 IVn + A8 V:p?[5]
U−B color index	−0.17[6]
B−V color index	−0.06[6]
Astrometry
μ Pic A
Radial velocity (Rv)	+0.40±1.00[7] km/s
Proper motion (μ)	RA: −1.302 mas/yr[1] Dec.: +1.637 mas/yr[1]
Parallax (π)	5.3553±0.0358 mas[1]
Distance	609 ± 4 ly (187 ± 1 pc)
Absolute magnitude (MV)	0.20[8]
μ Pic B
Proper motion (μ)	RA: +0.881 mas/yr[3] Dec.: +0.918 mas/yr[3]
Parallax (π)	5.3644±0.0286 mas[3]
Distance	608 ± 3 ly (186.4 ± 1.0 pc)
Absolute magnitude (MV)	3.75[8]
Details
μ Pic A
Mass	3.32[1] M☉
Radius	4.43[1] R☉
Luminosity	205[1] L☉
Surface gravity (log g)	3.612[1] cgs
Temperature	10,375[1] K
Rotational velocity (v sin i)	228[9] km/s
Age	258[1] Myr
μ Pic B
Mass	1.18[10] M☉
Radius	1.26[11] R☉
Luminosity	5.23[11] L☉
Surface gravity (log g)	4.25[10] cgs
Temperature	7,770[11] K
Other designations
μ Pic, CPD−58°722, HD 46860, HIP 31137, HR 2412, SAO 234564[12]
Database references
SIMBAD	μ Pic A
	μ Pic B

The primary, designated component A, is a blue-white star with a visual magnitude of 5.71^[2] and a stellar classification of B9 Ve^[4] or B9 IVn.^[5] The first classification suggests is a B-type main-sequence star, with the 'e' suffix indicating a Be star. The second may instead indicate a somewhat more evolved B-type star that is spinning rapidly, resulting in "nebulous" absorption lines. Photometrically, it shows a pulsation period of 0.397 days, which is likely the same as the rotation period.^[13]

The secondary companion, component B, is a white-hued star of magnitude 9.43^[2] with a classification of A8 V:p?.^[5] This indicates it is an A-type main-sequence star, with the 'p?' suffix suggesting it may be chemically peculiar while the ':' notation says there is some uncertainty about the general classification. The star has a radius of 1.26 R_☉ and a luminosity around 5.2 L_☉,^[11] values unusually low compared to the average for an A8-type dwarf star.^[14]