V1472 Aquilae

V1472 Aquilae

A light curve for V1472 Aquilae plotted from Hipparcos data, adapted from Samus (1997)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension 20h 05m 26.54594s[2]
Declination +15° 30′ 01.5408″[2]
Apparent magnitude (V) 6.34[3] (6.36 to 6.60)[4]
Characteristics
Spectral type M2.5III[1]
U−B color index +1.76[3]
B−V color index +1.64[3]
Variable type Candidate eclipsing variable[4]
Astrometry
Radial velocity (Rv)−111.7±0.3[5] km/s
Proper motion (μ) RA: 33.899[2] mas/yr
Dec.: 24.023[2] mas/yr
Parallax (π)4.1626 ± 0.1069 mas[2]
Distance780 ± 20 ly
(240 ± 6 pc)
Absolute magnitude (MV)−2.6±1.0[6]
Orbit[7]
Period (P)198.716±0.038 d
Semi-major axis (a)≥ 35.39 ± 0.76 Gm (0.2366 ± 0.0051 AU)
Eccentricity (e)0.048±0.016
Periastron epoch (T)2,443,721.1
Argument of periastron (ω)
(secondary)		99.3±29.7°
Semi-amplitude (K1)
(primary)		12.97±0.27 km/s
Details
Radius104±56[6] R☉
Luminosity1,100[6] L☉
Temperature3,670[8] K
Rotational velocity (v sin i)10[8] km/s
Other designations
V1472 Aql, BD+15°4040, HD 190658, HIP 98954, HR 7680, SAO 105663[9]
Database references
SIMBADdata

V1472 Aquilae is a triple star system in the equatorial constellation of Aquila. It is a variable star that ranges in brightness from 6.36 down to 6.60.[4] The system is located at a distance of approximately 780 light years from the Sun based on parallax. It is a high-velocity star system with a radial velocity of −112 km/s.[5] When it is at its brightest, it is very faintly visible to the naked eye under excellent observing conditions.

The binary nature of the main component was announced by P. B. Lucke and M. Mayor in 1982, who found it to be a single-lined spectroscopic binary with an orbital period of 198.7 days and an eccentricity of 0.05. At the time of its discovery, it was the shortest known binary period of any class M giant.[7] The primary is an aging red giant with a stellar classification of M2.5III.[1] It has a diameter 104±56 times and luminosity 1,100 times that of the Sun.[6] The star is a fast rotator with a projected rotational velocity of 10 km/s, possibly due to interaction with its companion.[8]

The variability of this star was discovered from Hipparcos data and, in 1997, it was classified as a semiregular variable with a period of 100.3727039 days. However, a plot of the light curve better matches that of an eclipsing binary or ellipsoidal variable. The 198-day orbital period produces a light curve with a primary and secondary minimum which, together with possible variations due to ellipsoidal rotation, produces the observed semiregular 100-day photometric variation.[1] Later observations show that it is less luminous than expected for a pulsating star with its amplitude, being more typical of ellipsoidal variables, and that it has a 200.05-day period with primary and secondary minima.[10]

A co-moving companion some 4.0 magnitudes fainter than the primary lies at an angular separation of 2.7 arcseconds.[1]

References

  1. ^ a b c d e Samus, N. N. (1997). "V1472 Aql: a Most Unusual Eclipser?". Information Bulletin on Variable Stars. 4501: 1. Bibcode:1997IBVS.4501....1S.
  2. ^ a b c d e 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.
  3. ^ a b c Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised ed. (Hoffleit+, 1991)". VizieR Online Data Catalog. Bibcode:1995yCat.5050....0H.
  4. ^ a b c Samus', N. N; et al. (2017). "General catalogue of variable stars". Astronomy Reports. GCVS 5.1. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
  5. ^ a b Famaey, B.; et al. (January 12, 2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data: Revisiting the concept of superclusters". Astronomy and Astrophysics. 430 (1): 165–186. arXiv:astro-ph/0409579. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272.
  6. ^ a b c d Boffin, H. M. J.; et al. (2014). "Roche-lobe filling factor of mass-transferring red giants: the PIONIER view". Astronomy & Astrophysics. 564: 13. arXiv:1402.1798. Bibcode:2014A&A...564A...1B. doi:10.1051/0004-6361/201323194. S2CID 118573930. A1.
  7. ^ a b Lucke, P. B.; Mayor, M. (January 1982). "Duplicity in the solar neighborhood. II. Spectroscopic orbits for four bright stars HD 21018, HD 30021, HD 158837 and HD 190658". Astronomy and Astrophysics. 105: 318–322. Bibcode:1982A&A...105..318L.
  8. ^ a b c Frankowski, A.; et al. (May 2009). "Spectroscopic binaries among Hipparcos M giants. II. Binary frequency". Astronomy and Astrophysics. 498 (2): 479–488. arXiv:0901.0937. Bibcode:2009A&A...498..479F. doi:10.1051/0004-6361/200810702. S2CID 15149456.
  9. ^ "HD 190658". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-03-02.
  10. ^ Tabur, V.; Bedding, T. R.; Kiss, L. L.; Giles, T.; Derekas, A.; Moon, T. T. (2010). "Period-luminosity relations of pulsating M giants in the solar neighbourhood and the Magellanic Clouds". Monthly Notices of the Royal Astronomical Society. 409 (2): 777–788. arXiv:1007.2974. Bibcode:2010MNRAS.409..777T. doi:10.1111/j.1365-2966.2010.17341.x. S2CID 118411237.