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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] Considered a solar analog, it was the target of the first radial velocity survey from Lick Observatory, which found a drift due to a companion.[6] In 2002, the cause of this was found to be brown dwarf companion B via direct imaging.[7]

15 Sagittae
Observation data
Epoch 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 0.600±0.005[2]
Astrometry
Radial velocity (Rv)4.57±0.1[4] km/s
Proper motion (μ) RA: −387.590[1] mas/yr
Dec.: −419.542[1] mas/yr
Parallax (π)56.426 ± 0.069 mas[1]
Distance57.80 ± 0.07 ly
(17.72 ± 0.02 pc)
Absolute magnitude (MV)4.55[2]
Orbit[3]
Period (P)73.3+2.2
−3.9 yr
Semi-major axis (a)18.3+0.4
−0.5 AU
Eccentricity (e)0.50±0.01
Inclination (i)97.3+0.4
−0.5°
Details[3]
15 Sge A
Mass1.08±0.04 M☉
Radius1.115±0.021 R☉
Luminosity1.338±0.032 L☉
Surface gravity (log g)4.42±0.06 cgs
Temperature5,883±59 K
Metallicity [Fe/H]0.05±0.07 dex
Rotation17.5±2.3
Rotational velocity (v sin i)4.42±0.06 km/s
Age2.5±1.8 Gyr
15 Sge B
Mass68.7+2.4
−3.1 MJup
Radius1.0±0.4 RJup
Luminosity0.000075±0.000016 L☉
Temperature1,510–1,850 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
SIMBADdata

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] but ten more years of observations found that the brown dwarf's orbit is viewed from nearly edge-on, is significantly eccentric and appeared to be moving in a circular orbit when first discovered, but is now approaching the primary as viewed from Earth.[3]


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. 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.
  3. 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.
  4. 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.
  5. "15 Sge". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-03-24.
  6. 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.
  7. "Brown dwarf found around nearby sun-like star" (Press release). Kamuela, Hawaii: W. M. Keck Observatory. January 1, 2002. Retrieved August 13, 2019.
  8. 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.



На других языках

[de] 15 Sagittae

15 Sagittae (kurz 15 Sge) ist ein etwa 58 Lichtjahre von der Erde entfernter Hauptreihenstern der Spektralklasse G0 im Sternbild Pfeil. Er ist mit einer scheinbaren Helligkeit von 5,8 mag mit dem bloßen Auge nur unter optimalen Bedingungen zu sehen. Der Stern wird von einem L-Zwerg mit der Bezeichnung 15 Sagittae B begleitet.
- [en] 15 Sagittae

[es] 15 Sagittae

15 Sagittae (15 Sge / HD 190406 / HR 7672)[1] es una estrella en la constelación de Sagitta, la flecha, localizada al sur de γ Sagittae, noroeste de ρ Delphini y noreste de Altair (α Aquilae). Tiene magnitud aparente +5,80[1] y se encuentra a 58 años luz del Sistema Solar. Forma un sistema binario con una enana marrón, descubierta en 2002.[2][3]

[ru] 15 Стрелы

15 Стрелы (лат. 15 Sagittae) — звезда, которая находится в созвездии Стрела на расстоянии около 57 световых лет от нас, её видимая звёздная величина составляет +5,8.


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