Upsilon Aquarii

Not to be confused with U Aquarii.

Upsilon Aquarii, Latinized from υ Aquarii, is the Bayer designation for a binary star^[9] system in the equatorial constellation of Aquarius. It is visible to the naked eye as a faint star with an apparent visual magnitude of 5.21.^[2] Parallax measurements give a distance estimate of 74.8 light-years (22.9 parsecs) from Earth.^[1] This is a high proper-motion star^[8] that is drifting closer to the Sun with a radial velocity of –2.3 km/s.^[1] It is part of the Hercules-Lyra association.^[9]

Upsilon Aquarii

Location of υ Aquarii (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Aquarius
Right ascension	22h 34m 41.63670s[1]
Declination	–20° 42′ 29.5745″[1]
Apparent magnitude (V)	+5.21[2]
Characteristics
Spectral type	F7 V[3]
B−V color index	+0.44[2]
Astrometry
Radial velocity (Rv)	−2.28±0.51[1] km/s
Proper motion (μ)	RA: +220.383[1] mas/yr Dec.: –147.225[1] mas/yr
Parallax (π)	43.5816 ± 0.1436 mas[1]
Distance	74.8 ± 0.2 ly (22.95 ± 0.08 pc)
Absolute magnitude (MV)	+3.44[4]
Details
A
Mass	1.4[5] M☉
Radius	1.49+0.04 −0.06[1] R☉
Luminosity	3.581±0.17[1] L☉
Surface gravity (log g)	4.11[6] cgs
Temperature	6,514±118[1] K
Metallicity [Fe/H]	0.08[5] dex
Rotational velocity (v sin i)	34.9[7] km/s
Age	900 Ma[4] 250+750 −50[5] Myr
Other designations
υ Aqr, 59 Aquarii, BD−21 6251, FK5 849, HD 213845, HIP 111449, HR 8592, SAO 191235[8]
Database references
SIMBAD	data

The primary component is an F-type main sequence star with a stellar classification of F7 V.^[3] It is less than a billion^[4][5] years old and is spinning with a projected rotational velocity of 35 km/s.^[7] The star has 1.4^[5] times the mass of the Sun and 1.5^[1] times the Sun's radius. It is radiating 3.6^[1] times the Sun's luminosity from its photosphere at an effective temperature of 6,597 K,^[6] giving it the yellow-white hue of an F-type star.^[10]

The star displays an excess of near infrared radiation, suggesting it has a circumstellar disk of dusty debris.^[11] This disk has a mean temperature of 75±17 K and is orbiting at an estimated radius of 84±41 AU.^[12] A faint stellar companion was detected in 2007 at the Gemini Observatory, with a separation of 6.09″±0.03″ from the primary.^[9] This is equivalent to a physical projected separation of 139 AU, which yields an estimated orbital period of ~1,330 years.^[13] The debris disk is orbiting close to the dynamically unstable region of this system.^[12]

References

1. 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.
2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
3. Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
4. Nordström, B.; et al. (May 2004), "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs", Astronomy and Astrophysics, 418: 989–1019, arXiv:astro-ph/0405198, Bibcode:2004A&A...418..989N, doi:10.1051/0004-6361:20035959, S2CID 11027621.
5. Vigan, A.; et al. (July 2017), "The VLT/NaCo large program to probe the occurrence of exoplanets and brown dwarfs at wide orbits. IV. Gravitational instability rarely forms wide, giant planets", Astronomy & Astrophysics, 603: 19, arXiv:1703.05322, Bibcode:2017A&A...603A...3V, doi:10.1051/0004-6361/201630133, S2CID 73635308, A3.
6. Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637, S2CID 119476992.
7. Schröder, C.; Reiners, Ansgar; Schmitt, Jürgen H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo" (PDF), Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377^{[permanent dead link‍]}
8. "* ups Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-03.
9. Lafrenière, David; et al. (2007), "The Gemini Deep Planet Survey", The Astrophysical Journal, 670 (2): 1367–1390, arXiv:0705.4290, Bibcode:2007ApJ...670.1367L, doi:10.1086/522826, S2CID 17295212.
10. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2013-12-03, retrieved 2012-07-02.
11. Ertel, S.; et al. (October 2014), "A near-infrared interferometric survey of debris-disk stars. IV. An unbiased sample of 92 southern stars observed in H band with VLTI/PIONIER", Astronomy & Astrophysics, 570: 20, arXiv:1409.6143, Bibcode:2014A&A...570A.128E, doi:10.1051/0004-6361/201424438, S2CID 9594917, A128.
12. Yelverton, Ben; Kennedy, Grant M.; Su, Kate Y. L.; Wyatt, Mark C. (2019), "A statistically significant lack of debris discs in medium separation binary systems", Monthly Notices of the Royal Astronomical Society, 488 (3): 3588–3606, arXiv:1907.04800, Bibcode:2019MNRAS.488.3588Y, doi:10.1093/mnras/stz1927, S2CID 195874349.
13. Rodriguez, David R.; et al. (May 2015), "Stellar multiplicity and debris discs: an unbiased sample", Monthly Notices of the Royal Astronomical Society, 449 (3): 3160–3170, arXiv:1503.01320, Bibcode:2015MNRAS.449.3160R, doi:10.1093/mnras/stv483.

External links

• Image Upsilon Aquarii