HD 142250

HIP 77900
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Right ascension 15h 54m 30.11s[1]
Declination −27° 20′ 19.09″[1]
Apparent magnitude (V) 6.10[1]
Characteristics
Spectral type B6Vp[2]
U−B color index -0.44[3]
B−V color index -0.07[3]
Astrometry
Radial velocity (Rv)-1.3[1] km/s
Proper motion (μ) RA: -13.27[1] mas/yr
Dec.: -25.08[1] mas/yr
Parallax (π)6.48 ± 0.61[1] mas
Distance500 ± 50 ly
(150 ± 10 pc)
Absolute magnitude (MV)-0.1[4]
Absolute bolometric
magnitude (Mbol)		-0.72 ± 0.20[5]
Details
Mass3.74 ± 0.10[2] M☉
Radius2.7 R☉
Luminosity220+38
−33[2] L☉
Surface gravity (log g)4.32[4] cgs
Temperature13,646 ± 94[2] K
Rotational velocity (v sin i)34.0 ± 1.3[6] km/s
Age11 ± 2[7] Myr
Other designations
BD−26 11096, HD 142250, HIP 77900, HR 5910, SAO 183907[1]
Database references
SIMBADdata

HD 142250 (HR 5910, HIP 77900) is a star in the constellation Scorpius. It has a visual apparent magnitude of 6.10,[1] being visible to the naked eye only in excellent seeing conditions. From parallax measurements, it is located about 500 light-years (155 parsecs) away from Earth.[1] This distance, together with the star's proper motion, indicate that HIP 77900 is a member of the Upper Scorpius subgroup of the Scorpius–Centaurus Association, the nearest OB association to the Sun.[8] This subgroup is the youngest of the three of the association, with an estimated age of 11 million years.[7]

This is a B-type main-sequence star with a spectral type of B6Vp and a mass estimated at 3.7 times the solar mass.[2] HIP 77900 is a helium-weak chemically peculiar star, and has a magnetic field and a slow rate of rotation, with a projected rotational velocity (v sin i) of 34 km/s.[6][3] Its photosphere is radiating light with a luminosity 220 times greater the Sun's at an effective temperature of 13,600 K.[2]

Stars in young stellar associations are frequent targets for direct imaging searches for sub-stellar objects, because these objects lose luminosity with time. A 2013 article, using data from the Pan-STARRS and UKIDSS surveys and follow up observations with the IRTF telescope, presented the discovery of an object of spectral type M9 and effective temperature of 2400 ± 150 K separated from HIP 77900 by 21.8 arcseconds, or more than 3200 ± 300 AU at the system's distance. Its mass, estimated from evolutionary models and assuming an age of 10 million years, is 20+7
−3 Jupiter masses, so the object is probably a low mass brown dwarf. The physical association between the two bodies has not been confirmed through common proper motion observation, but is considered likely given the proximity of the two objects in the sky and that the probable brown dwarf shows signs of youth.[5]

References

  1. 1 2 3 4 5 6 7 8 9 10 "HD 142250 -- Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2018-04-17
  2. 1 2 3 4 5 6 Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691.
  3. 1 2 3 Renson, P.; Manfroid, J. (May 2009), "Catalogue of Ap, HgMn and Am stars", Astronomy and Astrophysics, 498 (3): 961–966, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788.
  4. 1 2 de Geus, E. J.; de Zeeuw, P. T.; Lub, J. (June 1989), "Physical parameters of stars in the Scorpio-Centaurus OB association", Astronomy and Astrophysics, 216 (1–2): 44–61, Bibcode:1989A&A...216...44D
  5. 1 2 Aller, Kimberly M.; et al. (August 2013). "A Pan-STARRS + UKIDSS Search for Young, Wide Planetary-mass Companions in Upper Scorpius". The Astrophysical Journal. 773 (1): article 63, 15 pp. arXiv:1307.0506. Bibcode:2013ApJ...773...63A. doi:10.1088/0004-637X/773/1/63.
  6. 1 2 Wraight, K. T.; et al. (February 2012), "A photometric study of chemically peculiar stars with the STEREO satellites - I. Magnetic chemically peculiar stars", Monthly Notices of the Royal Astronomical Society, 420 (1): 757–772, arXiv:1110.6283, Bibcode:2012MNRAS.420..757W, doi:10.1111/j.1365-2966.2011.20090.x.
  7. 1 2 Pecaut, Mark J.; Mamajek, Eric E.; Bubar, Eric J. (February 2012). "A Revised Age for Upper Scorpius and the Star Formation History among the F-type Members of the Scorpius-Centaurus OB Association". The Astrophysical Journal. 746 (2): article 154, 22 pp. arXiv:1112.1695. Bibcode:2012ApJ...746..154P. doi:10.1088/0004-637X/746/2/154.
  8. ↑ de Zeeuw, P. T.; et al. (January 1999), "A HIPPARCOS Census of the Nearby OB Associations", The Astronomical Journal, 117 (1): 354–399, arXiv:astro-ph/9809227, Bibcode:1999AJ....117..354D, doi:10.1086/300682
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