HD 85390

HD 85390 is a star with an exoplanet companion in the southern constellation of Vela. It was given the proper name Natasha by Zambia during the 100th anniversary of the IAU. Natasha means "thank you" in many languages of Zambia.[8][9] This star is too faint to be seen with the naked eye, having an apparent visual magnitude of 8.54.[2] It is located at a distance of 109 light years from the Sun based on parallax, and is drifting further away with a radial velocity of 33 km/s.[1]

HD 85390 / Natasha
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Vela
Right ascension 09h 50m 02.4969s[1]
Declination –49° 47′ 24.9576″[1]
Apparent magnitude (V) 8.54[2]
Characteristics
Spectral type K1.5V[3]
Apparent magnitude (B) 9.395[2]
Apparent magnitude (J) 7.012±0.024[2]
Apparent magnitude (H) 6.612±0.033[2]
Apparent magnitude (K) 6.491±0.023[2]
B−V color index 0.855±0.003[2]
Astrometry
Radial velocity (Rv)33.03±0.20[4] km/s
Proper motion (μ) RA: 29.8018±0.0379 mas/yr[1]
Dec.: −60.245±0.058 mas/yr[1]
Parallax (π)29.8018 ± 0.0379 mas[1]
Distance109.4 ± 0.1 ly
(33.56 ± 0.04 pc)
Absolute magnitude (MV)5.99[2]
Details
Mass0.81±0.02 M☉[5]
0.813+0.043
−0.038[6] M☉
Radius0.78±0.01 R☉[5]
0.816+0.010
−0.011[6] R☉
Luminosity0.39±0.01[5] L☉
Surface gravity (log g)4.56±0.02[5] cgs
Temperature5,170±17 K[5]
5,182±20[6] K
Metallicity [Fe/H]–0.04[6] dex
Rotational velocity (v sin i)1.97±0.36[6] km/s
Age6.8±2.9 Gyr[5]
8.893+4.400
−4.017[6] Gyr
Other designations
Natasha, CD–49°4727, Gaia DR2 5406324138654973824, HD 85390, HIP 48235, SAO 221526, 2MASS J09500249-4947250[7]
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

The stellar classification of HD 85390 is K1.5V,[3] showing this to be a K-type main-sequence star. It is an older star with age estimates of 7–9 billion years, and is not considered chromospherically active.[10] The star is spinning with a projected rotational velocity of 2 km/s.[6] It is smaller, cooler, dimmer, and less massive than the Sun,[5] but the metallicity is near solar.[6]

Planetary system

The planet b was detected by the radial velocity method in 2011.[10] It is following an eccentric orbit at a distance of 1.4 AU from the host star.[11] An additional planet in the system was suspected since 2013,[12] only to be refuted in 2019.[11]

The HD 85390 planetary system[11]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b (Madalitso) ≥0.099 ± 0.010 MJ 1.373 ± 0.035 799.52 ± 2.41 0.50 ± 0.05 — —

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 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. Gray, R.O.; et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637. S2CID 119476992.
  4. 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.
  5. Bonfanti, A.; Ortolani, S.; Nascimbeni, V. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics. 585: 14. arXiv:1511.01744. Bibcode:2016A&A...585A...5B. doi:10.1051/0004-6361/201527297. S2CID 53971692. A5.
  6. Soto, M. G.; Jenkins, J. S. (2018). "Spectroscopic Parameters and atmosphEric ChemIstriEs of Stars (SPECIES). I. Code description and dwarf stars catalogue". Astronomy and Astrophysics. 615: A76. arXiv:1801.09698. Bibcode:2018A&A...615A..76S. doi:10.1051/0004-6361/201731533. S2CID 119107228.
  7. "HD 85390". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-26.
  8. "Approved names". NameExoworlds. Retrieved 2020-01-02.
  9. "International Astronomical Union | IAU". www.iau.org. Retrieved 2020-01-02.
  10. Mordasini, C.; et al. (2011). "The HARPS search for southern extrasolar planets XXIV. Companions to HD 85390, HD 90156, and HD 103197: a Neptune analog and two intermediate-mass planets". Astronomy and Astrophysics. 526. A111. arXiv:1010.0856. Bibcode:2011A&A...526A.111M. doi:10.1051/0004-6361/200913521.
  11. Wittenmyer, Robert A.; Clark, Jake T.; Zhao, Jinglin; Horner, Jonathan; Wang, Songhu; Johns, Daniel (2019), "Truly eccentric. I. Revisiting eight single-eccentric planetary systems", Monthly Notices of the Royal Astronomical Society, 484 (4): 5859–5867, arXiv:1901.08471, Bibcode:2019MNRAS.484.5859W, doi:10.1093/mnras/stz290, S2CID 118915974
  12. Wittenmyer, Robert A.; et al. (2013), "Forever alone? Testing single eccentric planetary systems for multiple companions", The Astrophysical Journal Supplement Series, 208 (1): 2, arXiv:1307.0894, Bibcode:2013ApJS..208....2W, doi:10.1088/0067-0049/208/1/2, S2CID 14109907
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