Astronomy:Epsilon2 Arae

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Short description: Star in the constellation Ara
For other star systems with this Bayer designation, see Epsilon Arae.
Epsilon2 Arae
The location of ε2 Arae (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Ara
Right ascension  17h 03m 08.754s[1]
Declination −53° 14′ 12.97″[1]
Apparent magnitude (V) 5.270[2] (5.44 + 8.65)[3]
Characteristics
Spectral type F5 V Fe+0.5[4] + DA3.2[5]
U−B color index +0.015[6]
B−V color index +0.498±0.005[2]
Astrometry
Radial velocity (Rv)+4.9[7] km/s
Proper motion (μ) RA: −22.409[1] mas/yr
Dec.: −143.793[1] mas/yr
Parallax (π)37.3696 ± 0.1347[1] mas
Distance87.3 ± 0.3 ly
(26.76 ± 0.10 pc)
Absolute magnitude (MV)3.27[8]
Orbit[9]
Primaryε2 Ara Aa
Companionε2 Ara Ab
Period (P)41.3 yr
Semi-major axis (a)0.589″
Eccentricity (e)0.622
Inclination (i)133.8°
Longitude of the node (Ω)73.6°
Details
ε2 Ara Aa
Mass1.40+0.01−0.02[10] M☉
Radius1.8[2] R☉
Luminosity4.56[2] L☉
Surface gravity (log g)4.29[8] cgs
Temperature6,577[8] K
Metallicity [Fe/H]+0.02[8] dex
Rotational velocity (v sin i)45.4[11] km/s
Age1.77+0.29−0.26[10] Gyr
ε2 Ara C
Mass0.66±0.07[12] M☉
Radius0.0124±0.0003[12] R☉
Surface gravity (log g)8.07±0.04[12] cgs
Temperature15,507±230[12] K
Other designations
CPD−53°8316, GC 22956, GJ 3985, HD 153580, HIP 83431, HR 6314, SAO 244388, PPM 345633, WDS J17031-5314A[6]
Database references
SIMBADdata

Epsilon2 Arae is a double star in the southern constellation of Ara. Its name is a Bayer designation that is Latinized from ε2 Arae, and abbreviated Epsilon2 Ara or ε2 Ara. Based on parallax measurements, it is 89 light-years (27 parsecs) distant from Earth. With a combined apparent visual magnitude of 5.27,[2] this system is faintly visible to the naked eye as a point of light.

The brighter star is a magnitude 5.44 F-type main sequence star with a stellar classification of F5 V Fe+0.5.[4] The Fe+0.5 notation indicates that it has a somewhat higher than normal abundance of iron. It has an estimated age of 1.8[10] billion years and a relatively high rate of rotation with a projected rotational velocity of 45 km/s.[11] This star has 1.4[10] times the mass of the Sun and 1.8 times the Sun's radius.[2] It is radiating 4.56[2] times the luminosity of the Sun from its photosphere at an effective temperature of 6,577 K.[8] The metallicity of the star, a measure of the abundance of more massive elements, is similar to the Sun.[8] It is a candidate pulsating star.[13]

There is a magnitude 8.65 stellar companion, component Ab, at an angular separation of 0.590 arcseconds.[3] The pair have an estimated orbital period of 41.3 years.[9] A common proper motion white dwarf companion, WD 1659-53, lies at an angular separation of 113.76″. Designated component C, it is magnitude 13.47 with a classification of DA3.2.[14][5]

References

  1. ↑ 1.0 1.1 1.2 1.3 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. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Schofield, Mathew et al. (2019), "The Asteroseismic Target List for Solar-like Oscillators Observed in 2 minute Cadence with the Transiting Exoplanet Survey Satellite", The Astrophysical Journal Supplement Series 241 (1): 12, doi:10.3847/1538-4365/ab04f5, Bibcode: 2019ApJS..241...12S. 
  3. ↑ 3.0 3.1 Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
  4. ↑ 4.0 4.1 Gray, R. O. et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I", The Astronomical Journal 132 (1): 161–170, doi:10.1086/504637, Bibcode: 2006AJ....132..161G. 
  5. ↑ 5.0 5.1 Holberg, J. B. et al. (November 2013), "Where are all the Sirius-like binary systems?", Monthly Notices of the Royal Astronomical Society 435 (3): 2077–2091, doi:10.1093/mnras/stt1433, Bibcode: 2013MNRAS.435.2077H. 
  6. ↑ 6.0 6.1 "* eps02 Ara". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+eps02+Ara. 
  7. ↑ Holmberg, J. et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics Supplement Series 501 (3): 941–947, doi:10.1051/0004-6361/200811191, Bibcode: 2009A&A...501..941H. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 Balachandran, Suchitra (May 1, 1990), "Lithium depletion and rotation in main-sequence stars", Astrophysical Journal, Part 1 354: 310–332, doi:10.1086/168691, Bibcode: 1990ApJ...354..310B. 
  9. ↑ 9.0 9.1 Tokovinin, Andrei (July 2017), "Orbit Alignment in Triple Stars" (in en), The Astrophysical Journal 844 (2): 103, doi:10.3847/1538-4357/aa7746, ISSN 0004-637X, Bibcode: 2017ApJ...844..103T. 
  10. ↑ 10.0 10.1 10.2 10.3 Aguilera-Gómez, Claudia et al. (June 2018), "Lithium abundance patterns of late-F stars: an in-depth analysis of the lithium desert", Astronomy & Astrophysics 614: A55, doi:10.1051/0004-6361/201732209, ISSN 0004-6361, Bibcode: 2018A&A...614A..55A. 
  11. ↑ 11.0 11.1 Schröder, C. et al. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo", Astronomy and Astrophysics 493 (3): 1099–1107, doi:10.1051/0004-6361:200810377, Bibcode: 2009A&A...493.1099S, http://goedoc.uni-goettingen.de/goescholar/bitstream/handle/1/9690/aa10377-08.pdf?sequence=2. 
  12. ↑ 12.0 12.1 12.2 12.3 Bédard, A. et al. (2017), "Measurements of Physical Parameters of White Dwarfs: A Test of the Mass-Radius Relation", The Astrophysical Journal 848 (1): 11, doi:10.3847/1538-4357/aa8bb6, Bibcode: 2017ApJ...848...11B. 
  13. ↑ Baade, D.; Kjeldsen, H. (July 1997), "A spectroscopic search for high azimuthal-order pulsation in broad-lined late F- and early G-stars.", Astronomy and Astrophysics 323: 429–441, Bibcode: 1997A&A...323..429B. 
  14. ↑ "GJ 2125 -- White Dwarf", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=GJ+2125, retrieved 2010-07-28. 



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