BD−08°2823

BD−08°2823 is a star with a pair of exoplanetary companions in the faint equatorial constellation of Sextans. The star has an apparent visual magnitude of 9.86,[2] which is too faint to be visible with the naked eye. This system is located at a distance of 135 light-years from the Sun based on parallax measurements, and is trending further away with a radial velocity of +53 km/s.[1] It is a high proper motion star that is traversing the celestial sphere at the angular rate of 0.369″ yr−1.[9]

BD−08°2823
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Sextans
Right ascension 10h 00m 47.7206s[1]
Declination –09° 31′ 00.0428″[1]
Apparent magnitude (V) 9.86[2]
Characteristics
Spectral type K4:V[3]
Apparent magnitude (B) 10.931[2]
Apparent magnitude (J) 7.960±0.020[2]
Apparent magnitude (H) 7.498±0.047[2]
Apparent magnitude (K) 7.323±0.021[2]
B−V color index 1.071±0.010[2]
Astrometry
Radial velocity (Rv)53.47±0.19[1] km/s
Proper motion (μ) RA: −375.517±0.066 mas/yr[1]
Dec.: 25.460±0.060 mas/yr[1]
Parallax (π)24.1641 ± 0.0397 mas[1]
Distance135.0 ± 0.2 ly
(41.38 ± 0.07 pc)
Absolute magnitude (MV)6.73[2]
Details
Mass0.741±0.020[4] M☉
Radius0.71±0.04[5] R☉
Luminosity0.237±0.001[1] L☉
Surface gravity (log g)4.33±0.26[6] cgs
Temperature4,746±63[7] K
Metallicity [Fe/H]−0.04±0.06[4] dex
Rotation26.6±1.5 days[7]
Rotational velocity (v sin i)1.4[7] km/s
Age5.0±4.7[4] Gyr
Other designations
BD−08°2823, Gaia DR2 3770419611540574080, HIP 49067, SAO 137286, PPM 192987, LTT 3669, NLTT 23181, Ross 444[8]
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

This is an ordinary K-type main-sequence star with a stellar classification of K4:V,[3] where the ':' notation indicates some uncertainty. Emission cores in the H and K lines suggest this is an active star, with the level of activity varying significantly over time.[7] It is roughly five billion years old[4] and is spinning with a projected rotational velocity of 1.4 km/s.[7] Measurements of the activity variation suggest a rotation period of around 27 days.[7] This star is smaller, cooler, and less massive than the Sun. Its metal content is slightly lower than in the Sun.[4] The star is radiating 24% of the luminosity of the Sun from its photosphere at an effective temperature of 4,746 K.[7]

Planetary system

In 2009, two planets were found in orbit around the star. They were discovered using the radial velocity method with the HARPS spectrograph in Chile, despite the data noise introduced through surface activity. The inner planet has a minimum mass equal to 14.4±2.1 times the mass of the Earth, while the outer planet is at least one third the mass of Jupiter.[7]

The BD−08°2823 planetary system[7]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥0.045 ± 0.007 MJ 0.056 ± 0.002 5.60 ± 0.02 0.15 ± 0.15 — —
c ≥0.33 ± 0.03 MJ 0.68 ± 0.02 237.6 ± 1.5 0.19 ± 0.09 — —

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. 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. Stephenson, C. B. (July 1986). "Dwarf K and M stars of high proper motion found in a hemispheric survey". Astronomical Journal. 92: 139–165. Bibcode:1986AJ.....92..139S. doi:10.1086/114146.
  4. Delgado Mena, E.; et al. (April 2019). "Abundance to age ratios in the HARPS-GTO sample with Gaia DR2. Chemical clocks for a range of [Fe/H]". Astronomy & Astrophysics. 624: 24. arXiv:1902.02127. Bibcode:2019A&A...624A..78D. doi:10.1051/0004-6361/201834783. S2CID 90259810. A78.
  5. Stassun, Keivan G.; et al. (2016). "Accurate Empirical Radii and Masses of Planets and Their Host Stars with Gaia Parallaxes". The Astronomical Journal. 153 (3): 136. arXiv:1609.04389. Bibcode:2017AJ....153..136S. doi:10.3847/1538-3881/aa5df3. S2CID 119219062.
  6. Delgado Mena, E.; et al. (October 2017). "Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program. II. Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu". Astronomy & Astrophysics. 606: 20. arXiv:1705.04349. Bibcode:2017A&A...606A..94D. doi:10.1051/0004-6361/201730535. S2CID 118908425. A94.
  7. Hébrard, G.; et al. (2010). "The HARPS search for southern extra-solar planets XX. Planets around the active star BD -08°2823". Astronomy and Astrophysics. 512. A46. arXiv:0912.3202. Bibcode:2010A&A...512A..46H. doi:10.1051/0004-6361/200913525. S2CID 73713738.
  8. "BD-08 2823". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-11-14.
  9. Luyten, W. J. (June 1995). "NLTT Catalogue". VizieR Online Data Catalog. Bibcode:1995yCat.1098....0L.
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