HD 4747

Last updated
HD 4747
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Cetus
Right ascension 00h 49m 26.76537s [1]
Declination −23° 12′ 44.9359″ [1]
Apparent magnitude  (V)7.155 [2]
Characteristics
Spectral type G8V
B−V color index 0.77
Astrometry
Radial velocity (Rv)9.893 ± 0.016 [3]  km/s
Proper motion (μ)RA: 516.92±0.55 [1]   mas/yr
Dec.: 120.05±0.45 [1]   mas/yr
Parallax (π)53.51 ± 0.53  mas [1]
Distance 61.0 ± 0.6  ly
(18.7 ± 0.2  pc)
Absolute magnitude  (MV)5.94
Orbit [4]
PrimaryHD 4747A
CompanionHD 4747B
Period (P)33.2±0.4 yr
Semi-major axis (a)10.0±0.2 AU
Eccentricity (e)0.7317±0.0014
Inclination (i)48.0±0.9°
Longitude of the node (Ω)89.4±1.1°
Periastron epoch (T)JD 2462615±155
Argument of periastron (ω)
(secondary)		267.2±0.5°
Semi-amplitude (K1)
(primary)		0.7553+0.0124
−0.0116 [5] km/s
Details
Mass 0.81 ± 0.02 [3] / ≥0.0440 ± 0.0022 [3]   M☉
Radius 0.785 ± 0.018 [6]   R☉
Luminosity 0.45 ± 0.02 (log -0.346 ± 0.04) [6]   L☉
Surface gravity (log g)4.48 ± 0.10 [7]   cgs
Temperature 5316 ± 50 [7]   K
Metallicity [Fe/H]-0.21 ± 0.05 [7]   dex
Age 0.1-7.3 (weakly constrained) [3]   Gyr
Other designations
CD−23 315, GJ  36, HIP  3850, SAO  166607 [2]
Database references
SIMBAD data

HD 4747 is a star that lies approximately 61 light-years away in the constellation of Cetus. The star is a low-amplitude spectroscopic binary, with the secondary being a directly detected brown dwarf.

Contents

Binarity

The binarity of HD 4747 was announced in 2002, based on observations with the HIRES spectrograph at the W. M. Keck Observatory. [8] The radial velocity variation caused by the companion was found to have a semi-amplitude of approximately 0.65 km/s, which evaded detection by earlier spectrographs due to their precision being poorer than about 1 km/s, but was easily detectable by the 3 m/s precision of HIRES. With a period of 6832 ± 653 days (the large error due to the orbit being unclosed over 1731 day span of observations) and an eccentricity of 0.64 ± 0.06, assuming a primary mass of 0.83 M☉ led to a minimum secondary mass of 42.3 MJ - well within the brown dwarf regime. HD 4747 B became one of the few brown dwarf candidates orbiting within a few AU of any type of star.

An updated orbital solution was provided in 2010, based on observations with the CORALIE spectrograph. [3] With a 3068-day extension to the radial velocity time series, the orbital period was found to be about twice as long as previously thought due to an increase in the fitted eccentricity. The minimum mass of the companion was increased slightly to 46.1 ± 2.3 MJ, remaining in the brown dwarf regime.

In 2013 an attempt to directly image the secondary using adaptive optics imaging at the W. M. Keck Observatory resulted in a non-detection, thus effectively eliminating the possibility of the companion being a low inclination stellar binary. A follow-up attempt in 2014 resulted in a candidate source that together with additional images taken in 2015 confirmed the companion as having common proper motion and also showed orbital motion in a counter-clockwise direction. [5]

HD 4747B

Photometry indicates that HD 4747B is most likely a L-type brown dwarf and may possibly be close to the transition between L and T-types. A preliminary dynamical mass was found to be 67.2±1.8 times the mass of Jupiter. [4]

Related Research Articles

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<span class="mw-page-title-main">Groombridge 34</span> Binary star system in the constellation of Andromeda

Groombridge 34 is a binary star system in the northern constellation of Andromeda. It was listed as entry number 34 in A Catalogue of Circumpolar Stars, published posthumously in 1838 by British astronomer Stephen Groombridge. Based upon parallax measurements taken by the Gaia spacecraft, the system is located about 11.6 light-years from the Sun. This positions the pair among the nearest stars to the Solar System.

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<span class="mw-page-title-main">HD 80606 and HD 80607</span> Binary star system in the constellation Ursa Major

HD 80606 and HD 80607 are two stars comprising a binary star system. They are approximately 217 light-years away in the constellation of Ursa Major. Both stars orbit each other at an average distance of 1,200 astronomical units. The binary system is listed as Σ1341 in the Struve Catalogue of Double Stars; however, this designation is not in wide use and the system is usually referred to by the HD designations of its constituent stars. An extrasolar planet has been confirmed to orbit HD 80606 in a highly elliptical orbit.

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<span class="mw-page-title-main">HD 114613</span> Star in the constellation Centaurus

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<span class="mw-page-title-main">HD 53680, HD 53705, and HD 53706</span> Quadruple star system in the constellation Puppis

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<span class="mw-page-title-main">HD 41742/41700</span> Multiple star system in the constellation Puppis

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HD 167665 is a yellow-white hued star with a brown dwarf companion in the southern constellation of Sagittarius. With an apparent visual magnitude of 6.39, it is near the lower brightness limit for stars that are visible to the naked eye. Based upon an annual parallax shift of 32.4 mas as seen from Earth, it is located 101 light years from the Sun. The star is moving away from the Sun with a radial velocity of +8 km/s.

References

  1. 1 2 3 4 5 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv: 0708.1752 . Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID   18759600. Vizier catalog entry
  2. 1 2 "HD 4747". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2022-12-22.
  3. 1 2 3 4 5 Sahlmann, J.; et al. (2011). "Search for brown-dwarf companions of stars". Astronomy and Astrophysics. 525. A95. arXiv: 1009.5991 . Bibcode:2011A&A...525A..95S. doi:10.1051/0004-6361/201015427. S2CID   119276951.
  4. 1 2 Xuan, Jerry W.; et al. (2022). "A Clear View of a Cloudy Brown Dwarf Companion from High-resolution Spectroscopy". The Astrophysical Journal. 937 (2): 54. arXiv: 2208.01657 . Bibcode:2022ApJ...937...54X. doi: 10.3847/1538-4357/ac8673 . S2CID   251280107.
  5. 1 2 Crepp, Justin R.; et al. (2016). "The TRENDS High-contrast Imaging Survey. VI. Discovery of a Mass, Age, and Metallicity Benchmark Brown Dwarf". The Astrophysical Journal. 831 (2). 136. arXiv: 1604.00398 . Bibcode:2016ApJ...831..136C. doi:10.3847/0004-637X/831/2/136. S2CID   38430082.
  6. 1 2 Valenti, J. A.; Fischer, D. A. (2005). "Spectroscopic Properties of Cool Stars (SPOCS). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs". The Astrophysical Journal Supplement Series. 159 (1): 141–166. Bibcode:2005ApJS..159..141V. doi: 10.1086/430500 .
  7. 1 2 3 Santos, N. C.; et al. (2005). "Spectroscopic metallicities for planet-host stars: Extending the samples". Astronomy and Astrophysics. 437 (3): 1127–1133. arXiv: astro-ph/0504154 . Bibcode:2005A&A...437.1127S. doi:10.1051/0004-6361:20052895. S2CID   16256304.
  8. ↑ Nidever, David L.; et al. (2002). "Radial Velocities for 889 Late-Type Stars". The Astrophysical Journal Supplement Series. 141 (2): 503–533. arXiv: astro-ph/0112477 . Bibcode:2002ApJS..141..503N. doi:10.1086/340570. S2CID   51814894.
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