G-type main sequence star in the constellation Sagitta
15 Sagittae
Observation dataEpoch J2000.0 Equinox J2000.0
Constellation
Sagitta
Right ascension 20h 04m 06.22091s [ 1]
Declination
+17° 04′ 12.6774″[ 1]
Apparent magnitude (V)5.80[ 2]
Characteristics
Evolutionary stage
main sequence
Spectral type
G0V + L4[ 3]
B−V color index
± 0.005[ 2]
Astrometry Radial velocity (Rv )± 0.1[ 4] Proper motion (μ) RA: −387.590[ 1] mas /yr Dec.: −419.542[ 1] mas /yr Parallax (π)56.426 ± 0.069 mas [ 1] Distance 57.80 ± 0.07 ly pc ) Absolute magnitude (MV )4.55[ 2] Orbit [ 3] Period (P)+2.2 yr Semi-major axis (a)+0.4 AU Eccentricity (e)± 0.01Inclination (i)+0.4 Details[ 3] 15 Sge A Mass ± 0.04M ☉ Radius ± 0.021R ☉ Luminosity ± 0.032L ☉ Surface gravity (log g )± 0.06cgs Temperature ± 59K Metallicity ± 0.07dex Rotation ± 2.3Rotational velocity (v sin i )± 0.06Age ± 1.8Gyr 15 Sge B Mass +2.4 M Jup Radius ± 0.4R Jup Luminosity 075 ± 0.000016 L ☉ Temperature 1,510–1,850 K Other designations 15 Sge ,
BD +16°4121,
GJ 779,
HD 190406,
HIP 98819,
HR 7672,
SAO 105635,
LFT 1517,
LHS 3515,
LTT 15872,
Wolf 866
[ 5] Database references SIMBAD data
15 Sagittae (15 Sge) is a star in the northern constellation Sagitta , located around 58 light years away from the Sun. It is visible to the naked eye as a faint, yellow-hued star with an apparent visual magnitude of 5.80.[ 2] solar analog , it was the target of the first radial velocity survey from Lick Observatory , which found a drift due to a companion.[ 6] brown dwarf companion B via direct imaging.[ 7]
The companion is a high-mass substellar brown dwarf of spectral class L4 ± 1.5, only a few Jupiter masses below the limit for stars, in a long-period orbit around the primary star. Imaged by the Keck telescope , was the first brown dwarf candidate orbiting a sun-like star detected via imaging and is currently the only known companion brown dwarf which both has a significant radial velocity trend on the primary that has also been imaged.
The brown dwarf was originally thought to have a semi-major axis of 14 AU and a circular orbit viewed from pole-on,[ 8] [ 3]
References
^ a b c d e 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 .^ a b c d Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters , 38 (5): 331, arXiv :1108.4971 Bibcode :2012AstL...38..331A , doi :10.1134/S1063773712050015 , S2CID 119257644 . ^ a b c d Crepp, Justin R.; et al. (June 2012). "The Dynamical Mass and Three-Dimensional Orbit of HR7672B: A Benchmark Brown Dwarf with High Eccentricity". The Astrophysical Journal . 751 (2): 14. arXiv :1112.1725 Bibcode :2012ApJ...751...97C . doi :10.1088/0004-637X/751/2/97 . S2CID 16113054 . 97. ^ Nidever, David L.; et al. (August 2002). "Radial Velocities for 889 Late-Type Stars". The Astrophysical Journal Supplement Series . 141 (2): 503– 522. arXiv :astro-ph/0112477 Bibcode :2002ApJS..141..503N . doi :10.1086/340570 . S2CID 51814894 . ^ "15 Sge" . SIMBAD Centre de données astronomiques de Strasbourg . Retrieved 2019-03-24 .^ Cumming, Andrew; et al. (December 1999). "The Lick Planet Search: Detectability and Mass Thresholds". The Astrophysical Journal . 526 (2): 890– 915. arXiv :astro-ph/9906466 Bibcode :1999ApJ...526..890C . doi :10.1086/308020 . S2CID 12560512 . ^ "Brown dwarf found around nearby sun-like star" (Press release). Kamuela, Hawaii: W. M. Keck Observatory. January 1, 2002. Retrieved August 13, 2019 .^ Liu, Michael C.; et al. (May 2002). "Crossing the Brown Dwarf Desert Using Adaptive Optics: A Very Close L-Dwarf Companion to the Nearby Solar Analog HR 7672". The Astrophysical Journal . 571 (1): 519– 527. arXiv :astro-ph/0112407 Bibcode :2002ApJ...571..519L . doi :10.1086/339845 . S2CID 11405638 .
External links
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