Astronomy:HD 193721
Observation data Epoch J2000.0 Equinox (celestial coordinates) | |
---|---|
Constellation | Octans |
Right ascension | 20h 33m 17.6366s[1] |
Declination | −80° 57′ 53.5944″[1] |
Apparent magnitude (V) | 5.77±0.01[2] |
Characteristics | |
Spectral type | G6/8 II[3] |
U−B color index | +0.85[4] |
B−V color index | +1.14[4] |
Astrometry | |
Radial velocity (Rv) | 8.6±0.7[5] km/s |
Proper motion (μ) | RA: +9.794[1] mas/yr Dec.: −16.081[1] mas/yr |
Parallax (π) | 4.2823 ± 0.165[1] mas |
Distance | 760 ± 30 ly (234 ± 9 pc) |
Absolute magnitude (MV) | −0.24[6] |
Details | |
Mass | 3.49[7] M☉ |
Radius | 24.38[8] R☉ |
Luminosity | 300±5[9] L☉ |
Surface gravity (log g) | 2.14±0.02[1] cgs |
Temperature | 4953±122[8] K |
Metallicity [Fe/H] | −0.15[10] dex |
Rotational velocity (v sin i) | 2.7±1.1[11] km/s |
Other designations | |
Database references | |
SIMBAD | data |
HD 193721 (HR 7785) is an astrometric binary[13] in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.77,[2] allowing it to be faintly seen with the naked eye. Parallax measurements place the system 760 light years[1] away from the Solar System and it is currently receding with a heliocentric radial velocity 8.6 km/s.[5]
HD 193721 has a stellar classification of G6/8 II[3] — intermediate between a G6 and 8 bright giant. At present it has 3.49 times the mass of the Sun,[7] but has expanded to 24.4 times its girth.[8] It shines with a luminosity of 300 solar luminosity[9] from its enlarged photosphere at an effective temperature of 4,953 K,[8] giving a yellow hue. HD 193721 is metal deficent with an iron abundance 71% that of the Sun[10] and spins leisurely with a projected rotational velocity of 2.7 km/s.[11]
The system has an companion designated CPD −81°900. The object has a spectral classification of F8[14] and is located 25.5″ along a position angle of 0° (as of 1998).[15] CPD −81°900 is a foreground object, having a higher parallax[16] and different proper motion.[15]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
- ↑ 2.0 2.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode: 2000A&A...355L..27H.
- ↑ 3.0 3.1 Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations -90_ to -53_ƒ0.. Bibcode: 1975mcts.book.....H.
- ↑ 4.0 4.1 Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory 4: 99–110. Bibcode: 1966CoLPL...4...99J.
- ↑ 5.0 5.1 Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. ISSN 1063-7737. Bibcode: 2006AstL...32..759G.
- ↑ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation" (in en). Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A.
- ↑ 7.0 7.1 Kervella, Pierre; Arenou, Frédéric; Thévenin, Frédéric (2022). "Stellar and substellar companions from Gaia EDR3". Astronomy & Astrophysics 657: A7. doi:10.1051/0004-6361/202142146. ISSN 0004-6361. Bibcode: 2022A&A...657A...7K.
- ↑ 8.0 8.1 8.2 8.3 Stassun, Keivan G. et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. ISSN 0004-6256. Bibcode: 2019AJ....158..138S.
- ↑ 9.0 9.1 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 10.0 10.1 Anders, F. et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics 628: A94. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. Bibcode: 2019A&A...628A..94A.
- ↑ 11.0 11.1 De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (January 2014). "A catalog of rotational and radial velocities for evolved stars: V. Southern stars⋆⋆⋆". Astronomy & Astrophysics 561: A126. doi:10.1051/0004-6361/201220762. ISSN 0004-6361. Bibcode: 2014A&A...561A.126D.
- ↑ "HR 7785". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HR+7785.
- ↑ Frankowski, A.; Jancart, S.; Jorissen, A. (19 December 2006). "Proper-motion binaries in the Hipparcos catalogue". Astronomy & Astrophysics 464 (1): 377–392. doi:10.1051/0004-6361:20065526. ISSN 0004-6361. Bibcode: 2007A&A...464..377F.
- ↑ Stoy, R. H. (1968). "Cape photographic catalague for 1950.0, zones −80° to −90°". Annals of the Cape Observatory 22. Bibcode: 1968AnCap..22.....S.
- ↑ 15.0 15.1 Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal 122 (6): 3466–3471. doi:10.1086/323920. ISSN 0004-6256. Bibcode: 2001AJ....122.3466M.
- ↑ Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
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