HD 203030

HD 203030, also known as V457 Vulpeculae, is a single, yellow-orange hued star with a sub-stellar companion in the northern constellation of Vulpecula. The designation HD 203030 is from the Henry Draper Catalogue, which is based on spectral classifications made between 1911 and 1915 by Annie Jump Cannon and her co-workers, and was published between 1918 and 1924. This star is invisible to the naked eye, having an apparent visual magnitude of 8.45.[2] It is located at a distance of 128 light years from the Sun based on parallax,[1] and is drifting closer with a radial velocity of −17 km/s.[5]

A light curve for V457 Vulpeculae, plotted from TESS data.[11] The period listed in the GCVS is marked in red.
HD 203030

HD 203030 location, 0.14 degrees FOV. The star is marked within the red diamond.
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Vulpecula
Right ascension 21h 18m 58.220s[1]
Declination 26° 13′ 49.96″[1]
Apparent magnitude (V) 8.45[2]
Characteristics
Evolutionary stage main sequence
Spectral type K0V[3]
B−V color index 0.750±0.015[2]
Variable type BY Dra[4]
Astrometry
Radial velocity (Rv)−16.92±0.26[5] km/s
Proper motion (μ) RA: 133.593±0.108 mas/yr[1]
Dec.: 9.563±0.11 mas/yr[1]
Parallax (π)25.4488 ± 0.0610 mas[1]
Distance128.2 ± 0.3 ly
(39.29 ± 0.09 pc)
Absolute magnitude (MV)5.436±0.030[6]
Details
Mass0.965±0.035[7] M☉
Radius0.86+0.02
−0.03[5] R☉
Luminosity0.593±0.002[5] L☉
Surface gravity (log g)4.64+0.03
−0.01[8] cgs
Temperature5,603+10
−8[8] K
Metallicity [Fe/H]0.06±0.07 dex
0.30+0.02
−0.01[8] dex
Rotational velocity (v sin i)5.62+0.13
−0.14[8] km/s
Age100+50
−70[9] Myr
Other designations
V457 Vul, Gaia DR2 1846882224145757056, HD 203030, HIP 105232, WDS 21190+2614, LTT 4041, TYC 2190-1095-1, 2MASS J21185820+2613500[10]
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

The stellar classification of HD 203030 is K0V,[3] indicating this is a K-type main-sequence star.[3] It is likely very young, belonging to the 45 million years old IC 2391 open cluster.[9] Based on photometric measurements by Hipparcos, it was found to exhibit low amplitude periodic variability with a range of 0.0139 in magnitude and a period of 4.14 days.[12] However the General Catalog of Variable Stars lists its period as 6.664 days.[4] It is now classified as a chromospherically active BY Draconis variable.[4] The star has 97%[7] of the mass of the Sun and 86%[5] of the Sun's radius. It is radiating 59%[5] of the luminosity of the Sun from its photosphere at an effective temperature of 5,603 K.[8]

Planetary system

In 2006, direct imaging found co-moving companion at a projected separation of 487.1±1.8 AU, suggesting this is a candidate brown dwarf of spectral class L7.5.[13] It was shown to be in a bound orbit around the star by 2014.[7] In 2017, a reanalysis indicated that the star HD 203030 is probably very young, and therefore both the primary and the observed companion are less massive than previously thought. This places the companion object at the planetary mass boundary.[9] In 2019, the rotational period of HD 203030 B was measured as 7.5+0.6
−0.5 hours, and a patchy cloud cover was detected.[6]

The HD 203030 planetary system[9]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
B 11+4
−3 MJ		 487 — — — —

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. Frasca, A.; et al. (May 1, 2018). "A spectroscopic survey of the youngest field stars in the solar neighborhood . II. The optically faint sample". Astronomy and Astrophysics. 612: A96. arXiv:1801.00671. Bibcode:2018A&A...612A..96F. doi:10.1051/0004-6361/201732028. ISSN 0004-6361. S2CID 119537437.
  4. Samus, N. N.; et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 255195566.
  5. 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.
  6. Miles-Páez, Paulo A.; et al. (2019). "Cloud Atlas: Variability in and out of the Water Band in the Planetary-mass HD 203030B Points to Cloud Sedimentation in Low-gravity L Dwarfs". The Astrophysical Journal. 883 (2): 181. arXiv:1908.09403. Bibcode:2019ApJ...883..181M. doi:10.3847/1538-4357/ab3d25. S2CID 201696377.
  7. Ginski, C.; et al. (2014). "Astrometric follow-up observations of directly imaged sub-stellar companions to young stars and brown dwarfs★". Monthly Notices of the Royal Astronomical Society. 444 (3): 2280–2302. arXiv:1409.1850. Bibcode:2014MNRAS.444.2280G. doi:10.1093/mnras/stu1586. S2CID 119118750.
  8. Swastik, C.; et al. (March 2021). "Host Star Metallicity of Directly Imaged Wide-orbit Planets: Implications for Planet Formation". The Astronomical Journal. 161 (3): 13. arXiv:2012.13694. Bibcode:2021AJ....161..114S. doi:10.3847/1538-3881/abd802. S2CID 229679749. 114.
  9. Miles-Páez, Paulo A.; et al. (2017). "The Prototypical Young L/T-Transition Dwarf HD 203030B Likely Has Planetary Mass". The Astronomical Journal. 154 (6): 262. arXiv:1710.11274. Bibcode:2017AJ....154..262M. doi:10.3847/1538-3881/aa9711. S2CID 67821107.
  10. "HD 203030". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2022-01-28.{{cite web}}: CS1 maint: postscript (link)
  11. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 27 May 2022.
  12. Koen, Chris; Eyer, Laurent (March 2002). "New periodic variables from the Hipparcos epoch photometry". Monthly Notices of the Royal Astronomical Society. 331 (1): 45–59. arXiv:astro-ph/0112194. Bibcode:2002MNRAS.331...45K. doi:10.1046/j.1365-8711.2002.05150.x. S2CID 10505995.
  13. Metchev, Stanimir A.; Hillenbrand, Lynne A. (2006). "HD 203030B: An Unusually Cool Young Substellar Companion near the L/T Transition". The Astrophysical Journal. 651 (2): 1166–1176. arXiv:astro-ph/0607514. Bibcode:2006ApJ...651.1166M. doi:10.1086/507836. S2CID 16571973.
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