AB Pictoris

AB Pictoris (abbreviated AB Pic, also catalogued as HD 44627) is a K-type star, approximately 163 light-years away in the constellation of Pictor.[2][1] It has been identified as a member of the young (30 million years old) Tucana–Horologium association.[7] The star has also been classified as a BY Draconis variable.[3] 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.[8]

AB Pictoris

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 12.9130s[1]
Declination −58° 03′ 15.5249″[1]
Apparent magnitude (V) 9.16[2]
Characteristics
Spectral type K2V[2]
B−V color index 0.8[2]
Variable type BY[3]
Astrometry
Radial velocity (Rv)22.2 ± 0.3[2] km/s
Proper motion (μ) RA: 14.339±0.062[1] mas/yr
Dec.: 45.072±0.063[1] mas/yr
Parallax (π)19.9521 ± 0.0291[1] mas
Distance163.5 ± 0.2 ly
(50.12 ± 0.07 pc)
Absolute magnitude (MV)5.87[4]
Details
Temperature4800[5] K
Metallicity[Fe/H] = −0.64[5]
Rotational velocity (v sin i)12[5] km/s
Age3 × 107 to 4 × 107  [6] years
Other designations
AB Pic, CD−58 1409, CPD−58 670, HD 44627A, HD 44627, HIP 30034, PPM 335089, SAO 234448.[2]
Database references
SIMBADdata

Possible 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.[8] 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.[6] 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.[8]

The AB Pictoris system
Companion MassObserved separation
(AU)		Discovery year
b13.5 ± 0.5[9] MJ275[9]2005[9]
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See also

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. "V* AB Pic". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 3, 2008.
  3. AB Pic, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line October 3, 2008.
  4. From apparent magnitude and parallax.
  5. HD 44627, database entry, The Geneva-Copenhagen Survey of Solar neighbourhood, J. Holmberg et al., 2007, CDS ID V/117A. Accessed on line November 19, 2008.
  6. Homogeneous comparison of directly detected planet candidates: GQ Lup, 2M1207, AB Pic, Ralph Neuhaeuser, ESO Workshop Proceedings on Multiple Stars, Bibcode: 2005astro.ph..9906N, arXiv:astro-ph/0509906.
  7. New Members of the TW Hydrae Association, β Pictoris Moving Group, and Tucana/Horologium Association, Inseok Song, B. Zuckerman, and M. S. Bessell, The Astrophysical Journal 599, #1 (December 2003), pp. 342–350, Bibcode: 2003ApJ...599..342S, doi:10.1086/379194.
  8. A companion to AB Pic at the planet/brown dwarf boundary, G. Chauvin, A.-M. Lagrange, B. Zuckerman, C. Dumas, D. Mouillet, I. Song, J.-L. Beuzit, P. Lowrance, and M. S. Bessell, Astronomy and Astrophysics 438, #3 (August 2005), pp. L29–L32, Bibcode: 2005A&A...438L..29C, doi:10.1051/0004-6361:200500111, arXiv:astro-ph/0504658.
  9. Jean Schneider (2011). "Notes for Planet AB Pic b". Extrasolar Planets Encyclopaedia. Retrieved 12 October 2011.
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