AB Pictoris
Star in the constellation Pictor
From Wikipedia, the free encyclopedia
AB Pictoris (abbreviated AB Pic, also catalogued as HD 44627) is a K-type main-sequence star, located 163.5 light-years away in the southern constellation of Pictor.[1] It has been identified as a member of the young (30 million years old) Tucana–Horologium association.[10] The star has been classified as a BY Draconis variable,[4] indicating it has an active chromosphere. It is an X-ray source and displays emission lines in its spectrum.[11][2]
Coronagraphic image of AB Pictoris showing its tiny companion (bottom left). The data was obtained on 16 March 2003 with NACO on the VLT, using a 1.4 arcsec occulting mask on top of AB Pictoris. | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Pictor |
| Right ascension | 06h 19m 12.913s[1] |
| Declination | −58° 03′ 15.53″[1] |
| Apparent magnitude (V) | 9.13[2] |
| Characteristics | |
| Evolutionary stage | main sequence[1] |
| Spectral type | K1V(e)[2] |
| B−V color index | 0.861±0.027[3] |
| Variable type | BY Dra[4] |
| Astrometry | |
| Radial velocity (Rv) | 22.6±0.3[2] km/s |
| Proper motion (μ) | RA: 14.314±0.015 mas/yr[1] Dec.: 45.234±0.017 mas/yr[1] |
| Parallax (π) | 19.9452±0.0124 mas[1] |
| Distance | 163.5 ± 0.1 ly (50.14 ± 0.03 pc) |
| Absolute magnitude (MV) | 5.82[3] |
| Details | |
| Mass | 0.90±0.10[5] M☉ |
| Radius | 0.92±0.03[6] R☉ |
| Luminosity | 0.51[3] L☉ |
| Surface gravity (log g) | 4.67±0.09[5] cgs |
| Temperature | 5,188±50[6] K |
| Metallicity [Fe/H] | −0.54[3] dex |
| Rotation | 3.90±0.08 d[7] |
| Rotational velocity (v sin i) | 10.87±0.08[7] km/s |
| Age | 13.3+1.1 −0.6[8] Myr |
| Other designations | |
| AB Pic, CD−58 1409, CPD−58 670, HD 44627A, 44627, HIP 30034, SAO 234448, PPM 335089[9] | |
| Database references | |
| SIMBAD | data |
In 2005 it was announced that an astronomical object (AB Pictoris b, abbreviated AB Pic b) had been imaged in 2003 and 2004 close to and apparently in orbit around the star. Its mass suggests that it is at the borderline between being a brown dwarf or a planet.[12]
Planetary system
In 2003 and 2004, an object (now catalogued as AB Pictoris b) was observed close to the star by a team of astronomers at the European Southern Observatory. Since it had common proper motion with AB Pictoris, it was concluded that it was physically close to the star. Its spectral type was estimated as between L0V and L3V. Using evolutionary models, its mass was estimated as from 13 to 14 Jupiter masses.[12] However, because modelling such young objects is difficult, this estimate is very uncertain; some models give masses as low as 11 Jupiter masses or as high as 70 Jupiter masses. Temperature estimates range from 1600 K to 2400 K.[14] As it is not known if the mass of the object exceeds the deuterium burning limit of 13 Jupiter masses, it is not clear whether the object should be classified as an extrasolar planet or a brown dwarf.[12] In 2010 a team obtained the spectrum of AB Pic b with VLT/SINFONI. This confirmed this object as an L-dwarf with low surface gravity, matching a spectral type of L0-L1. It also constrained the temperature to 2000+100
−300 Kelvin.[15] Another team found that AB Pic b has a lower temperature of 1400-1700 K and possibly a lower mass (7-14 MJ, from figure 13).[16] A later analysis did find a temperature of 1800+100
−200 K and a mass of 10-14 MJ.[17] The planet shows several molecular and atomic absorption lines in the spectrum. The most notable are water vapor, carbon monoxide, potassium and sodium. The planetary orbit is significantly misaligned with its spin axis orientation (obliquity), possibly due to gravitational interactions with the additional inner planet.[18]
An additional planet, AB Pictoris c, was first suspected by combining direct imaging, radial velocity and the astrometric acceleration from AB Pic A.[18] The planet was confirmed in 2025 with a re-analysis of the Gaia excess noise and the proper motion anomaly.[19]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| c | 2.5–9[19] MJ | 3–5[19] | — | — | — | — |
| b | 10±1 MJ | 190+200 −50 |
— | — | 90±12° | 1.8±0.2 RJ |
See also
- Beta Pictoris
- GQ Lupi
- List of exoplanets discovered between 2000–2009 - including AB Pictoris b
- List of exoplanets discovered in 2025 - including AB Pictoris c