HD 196737

HD 196737, also designated as HR 7893, is a solitary orange hued star^[17] located in the southern constellation Microscopium. It has an apparent magnitude of 5.47,^[2] allowing it to be faintly visible to the naked eye. The object is located relatively close at a distance of 241 light years based on Gaia DR3 parallax measurements,^[1] but is receding with a heliocentric radial velocity of 14.2 km/s.^[6] At its current distance, HD 196737's brightness is diminished by 0.14 magnitudes due to interstellar dust.^[18] It has an absolute magnitude of 1.17.^[7]

HD 196737

Location of HD 196737 (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Microscopium
Right ascension	20h 40m 19.82792s[1]
Declination	−33° 25′ 54.6462″[1]
Apparent magnitude (V)	5.47±0.01[2]
Characteristics
Evolutionary stage	red giant branch[3]
Spectral type	K1 III[4]
U−B color index	+1.08[5]
B−V color index	+1.12[5]
Astrometry
Radial velocity (Rv)	14.2±2.8[6] km/s
Proper motion (μ)	RA: +21.953 mas/yr[1] Dec.: +34.487 mas/yr[1]
Parallax (π)	13.5581 ± 0.0691 mas[1]
Distance	241 ± 1 ly (73.8 ± 0.4 pc)
Absolute magnitude (MV)	+1.17[7]
Details
Mass	1.4±0.1[8] M☉
Radius	11.5[9] R☉
Luminosity	43.7+3.1 −2.9[10] L☉
Surface gravity (log g)	2.46±0.34[11] cgs
Temperature	4,681±122[12] K
Metallicity [Fe/H]	−0.02[13] dex
Rotational velocity (v sin i)	<1[14] km/s
Age	3.4±0.6[8] Gyr
Other designations
13 G. Microscopii[15], CD−33°15119, CPD−33°5922, FK5 1540, GC 28776, HD 196737, HIP 102014, HR 7893, SAO 212333[16]
Database references
SIMBAD	data

This is an evolved giant star with a stellar classification of K1 III.^[4] HD 196737 is estimated to be 3.4 billion years old based on asteroseismologic measurements,^[8]enough for it to cool and expand onto the red giant branch; it is now fusing a hydrogen shell around an inert helium core.^[3] It has 1.4 time the mass of the Sun^[8] and an enlarged radius of 11.5 R_☉.^[9] It radiates 43.7 times the luminosity of the Sun^[10] from its photosphere at an effective temperature of 4,681 K.^[12] HD 196737 has a solar metallicity — what astronomers dub chemical elements heavier than helium. The star has a projected rotational velocity too low to be measured accurately.^[14]

References

1. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
2. Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN 0004-6361.
3. Jones, M. I.; Jenkins, J. S.; Rojo, P.; Melo, C. H. F. (December 2011). "Study of the impact of the post-MS evolution of the host star on the orbits of close-in planets: I. Sample definition and physical properties⋆⋆⋆". Astronomy & Astrophysics. 536: A71. arXiv:1110.6459. Bibcode:2011A&A...536A..71J. doi:10.1051/0004-6361/201117887. ISSN 0004-6361.
4. Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Volume III: Declinations −40° to −26°. Bibcode:1982mcts.book.....H.
5. Oja, T. (1970). "UBV-Fotometri danska Tel (ESO)". Private Communication: 0. Bibcode:1970Priv.........0O.
6. 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. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.
7. Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
8. Aguirre, Víctor Silva; et al. (29 January 2020). "Detection and Characterization of Oscillating Red Giants: First Results from the TESS Satellite". The Astrophysical Journal. 889 (2): L34. arXiv:1912.07604. Bibcode:2020ApJ...889L..34S. doi:10.3847/2041-8213/ab6443. eISSN 2041-8213.
9. Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (October 2004). "The angular sizes of dwarf stars and subgiants". Astronomy & Astrophysics. 426 (1): 297–307. arXiv:astro-ph/0404180. Bibcode:2004A&A...426..297K. doi:10.1051/0004-6361:20035930. eISSN 1432-0746. ISSN 0004-6361.
10. Charbonnel, C.; Lagarde, N.; Jasniewicz, G.; North, P. L.; Shetrone, M.; Krugler Hollek, J.; Smith, V. V.; Smiljanic, R.; Palacios, A.; Ottoni, G. (January 2020). "Lithium in red giant stars: Constraining non-standard mixing with large surveys in the Gaia era". Astronomy & Astrophysics. 633: A34. arXiv:1910.12732. Bibcode:2020A&A...633A..34C. doi:10.1051/0004-6361/201936360. eISSN 1432-0746. ISSN 0004-6361.
11. Allende Prieto, C.; Lambert, D. L. (December 1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. ISSN 0004-6361.
12. Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. eISSN 1538-3881. hdl:1721.1/124721. S2CID 166227927.
13. McWilliam, Andrew (December 1990). "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances". The Astrophysical Journal Supplement Series. 74: 1075. Bibcode:1990ApJS...74.1075M. doi:10.1086/191527. eISSN 1538-4365. ISSN 0067-0049.
14. 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". Astronomy & Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762. eISSN 1432-0746. ISSN 0004-6361.
15. Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode:1879RNAO....1.....G.
16. "HD 196737". SIMBAD. Centre de données astronomiques de Strasbourg.
17. Eggleton, P. P.; Tokovinin, A. A. (11 September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. eISSN 1365-2966. ISSN 0035-8711.
18. Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society. 472 (4): 3805–3820. arXiv:1709.01160. Bibcode:2017MNRAS.472.3805G. doi:10.1093/mnras/stx2219. eISSN 1365-2966. ISSN 0035-8711.