Astronomy:HD 98617

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Short description: Double star in the constellation Chamaeleon
HD 98617
Chamaeleon constellation map.svg
Red circle.svg
Location of HD 98617 on the map (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Chamaeleon
Right ascension  11h 18m 34.40370s[1]
Declination −79° 40′ 07.1370″[1]
Apparent magnitude (V) 6.35±0.01[2]
Characteristics
Evolutionary stage main sequence[1]
Spectral type A8 IIIm:[3]
U−B color index +0.08[4]
B−V color index +0.26[4]
Astrometry
Radial velocity (Rv)−4±2.1[5] km/s
Proper motion (μ) RA: +46.293[1] mas/yr
Dec.: −37.910[1] mas/yr
Parallax (π)15.7985 ± 0.069[1] mas
Distance206.4 ± 0.9 ly
(63.3 ± 0.3 pc)
Absolute magnitude (MV)+2.42[6]
Details
Mass1.75±0.07[7] M☉
Radius1.85±0.06[8] R☉
Luminosity8.41[9] L☉
Surface gravity (log g)4.20±0.04[7] cgs
Temperature7,540±276[10] K
Metallicity [Fe/H]−0.03[11] dex
Age1.06[11] Gyr
Other designations
CD−78°457, CPD−78°638, FK5 2904, GC 15572, HD 98617, HIP 55225, HR 4385, SAO 256823, WDS J11186-7940AB[12]
Database references
SIMBADdata

HD 98617, also known HR 4385, is a double star located in the southern circumpolar constellation Chamaeleon. The system has a combined apparent magnitude of 6.35,[2] placing it near the limit for naked eye. The system is located relatively close at a distance of 206 light years[1] but is approaching the Solar System with a fairly constrained radial velocity of −4 km/s.[5] At its current distance, HD 98617 brightness is diminished by 0.29 magnitudes due to interstellar dust.[13]

The system's nature as a double star was first observed in a 1991 Hipparcos multiplicity survey. Their current separation is six-tenths of an arcsecond, making it difficult to measure the properties of the individual components. Nevertheless, the 10th magnitude companion is located along a position angle of 237° as of 2018.[14]

The primary has a stellar classification of A8 IIIm:, indicating that it is an evolved Am star (with uncertainty).[3] However, Renson and Manfroid (2009) lists its chemical peculiarity to be doubtful.[15] It has 1.75 times the mass of the Sun[7] and 1.85 times its girth.[8] It radiates 8.41 times the luminosity of the Sun[9] from its photosphere at an effective temperature of 7,540 K,[10] giving it a white hue. It is estimated to be a billion years old and has a solar metallicity.[11] The aforementioned parameters belong to an A-type main-sequence star instead of a giant star and Gaia DR3 even models it as such.[1]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 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. ↑ 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°. Bibcode: 1975mcts.book.....H. 
  4. ↑ 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. ↑ 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. 
  6. ↑ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  7. ↑ 7.0 7.1 7.2 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. ISSN 0004-6361. Bibcode: 1999A&A...352..555A. 
  8. ↑ 8.0 8.1 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. Bibcode: 2019AJ....158..138S. 
  9. ↑ 9.0 9.1 Chandler, Colin Orion; McDonald, Iain; Kane, Stephen R. (17 February 2016). "The Catalog of Earth-Like Exoplanet Survey Targets (CELESTA): A Database of Habitable Zones Around Nearby Stars". The Astronomical Journal 151 (3): 59. doi:10.3847/0004-6256/151/3/59. Bibcode: 2016AJ....151...59C. 
  10. ↑ 10.0 10.1 Bai, Yu; Liu, JiFeng; Bai, ZhongRui; Wang, Song; Fan, DongWei (2 August 2019). "Machine-learning Regression of Stellar Effective Temperatures in the Second Gaia Data Release". The Astronomical Journal 158 (2): 93. doi:10.3847/1538-3881/ab3048. Bibcode: 2019AJ....158...93B. 
  11. ↑ 11.0 11.1 11.2 Gontcharov, G. A. (December 2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters 38 (12): 771–782. doi:10.1134/S1063773712120031. ISSN 1063-7737. Bibcode: 2012AstL...38..771G. 
  12. ↑ "HD 98617". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+98617. 
  13. ↑ 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. doi:10.1093/mnras/stx2219. ISSN 0035-8711. Bibcode: 2017MNRAS.472.3805G. 
  14. ↑ 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. 
  15. ↑ Renson, P.; Manfroid, J. (19 March 2009). "Catalogue of Ap, HgMn and Am stars". Astronomy & Astrophysics 498 (3): 961–966. doi:10.1051/0004-6361/200810788. ISSN 0004-6361. Bibcode: 2009A&A...498..961R. 
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