Chi Aquarii

χ Aquarii
	Location of χ Aquarii (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Aquarius
Right ascension	23h 16m 50.93916s
Declination	−07° 43′ 35.4023″
Apparent magnitude (V)	4.75 - 5.10
Characteristics
Spectral type	M3 III
U−B color index	+1.60
B−V color index	+1.60
Variable type	SRb?
Astrometry
Radial velocity (Rv)	−13.72 ± 0.86 km/s
Proper motion (μ)	RA: −19.18 mas/yr ; Dec.: −14.10 mas/yr
Parallax (π)	5.32 ± 0.37 mas
Distance	610 ± 40 ly ; (190 ± 10 pc)
Absolute magnitude (MV)	−1.43
Details
Radius	142 R☉
Luminosity	2,598 L☉
Surface gravity (log g)	0.128 cgs
Temperature	3,456 K
Other designations
	χ Aqr, 92 Aquarii, BD−08 6076, HD 219576, HIP 114939, HR 8850, SAO 146612.
Database references
SIMBAD	data

Chi Aquarii, Latinized from χ Aquarii, is the Bayer designation of a star in the equatorial constellation of Aquarius. The distance to this star, based upon parallax measurements with a 7% margin of error, is roughly 610 light-years (190 parsecs). It is visible to the naked eye with an apparent visual magnitude of about 5.

A light curve for Chi Aquarii, plotted from *Hipparcos* data^[9]

This is a red giant star with a spectral classification of M3 III.^[3] The interferometry-measured angular diameter of this star is 6.70 ± 0.15 mas,^[10] which, at its estimated distance, equates to a physical radius of about 137 times the radius of the Sun.^[a] It is classified as a semi-regular variable star and its brightness varies by an amplitude of 0.0636 in magnitude.^[11] The identified pulsation periods are 32.3, 38.5, and 44.9 days.^[12]

Notes

^ ^a ^b The radius (R_*) is given by $2\cdot R_{*}={\frac {(190\cdot 6.70\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\approx 274\cdot R_{\bigodot }.$ ^[13]

References

^ ^a ^b ^c ^d ^e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
^ ^a ^b Samus, N. N.; Durlevich, O. V.; et al. (2009), "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)", VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S, 1, Bibcode:2009yCat....102025S.
^ ^a ^b Crampton, D.; Lloyd Evans, T. (1973), "Spectroscopic observations of M giant stars at the South Galactic Pole", Monthly Notices of the Royal Astronomical Society, 162: 11–15, Bibcode:1973MNRAS.162...11C, doi:10.1093/mnras/162.1.11.
^ ^a ^b Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.
^ Famaey, B.; et al. (May 2009), "Spectroscopic binaries among Hipparcos M giants. I. Data, orbits, and intrinsic variations", Astronomy and Astrophysics, 498 (2): 627–640, arXiv:0901.0934, Bibcode:2009A&A...498..627F, doi:10.1051/0004-6361/200810698, S2CID 18739721.
^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
^ ^a ^b ^c ^d McDonald, I.; Zijlstra, A. A.; Watson, R. A. (15 June 2017), "Fundamental parameters and infrared excesses of Tycho–Gaia stars", Monthly Notices of the Royal Astronomical Society, 471 (1): 770–791, arXiv:1706.02208, Bibcode:2017MNRAS.471..770M, doi:10.1093/mnras/stx1433, eISSN 1365-2966, ISSN 0035-8711.
^ "chi Aqr -- Semi-regular pulsating Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-05.
^ "/ftp/cats/more/HIP/cdroms/cats", Centre de Données astronomiques de Strasbourg, Strasbourg astronomical Data Center, retrieved 15 October 2022.
^ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
^ Koen, Chris; Eyer, Laurent (March 2002), "New periodic variables from the Hipparcos epoch photometry", Monthly Notices of the Royal Astronomical Society, 331 (1): 45–59, arXiv:astro-ph/0112194, Bibcode:2002MNRAS.331...45K, doi:10.1046/j.1365-8711.2002.05150.x, S2CID 10505995.
^ Tabur, V.; et al. (December 2009), "Long-term photometry and periods for 261 nearby pulsating M giants", Monthly Notices of the Royal Astronomical Society, 400 (4): 1945–1961, arXiv:0908.3228, Bibcode:2009MNRAS.400.1945T, doi:10.1111/j.1365-2966.2009.15588.x, S2CID 15358380.
^ Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1

External links

Image Chi Aquarii

[radius-11] The radius (R_*) is given by $2\cdot R_{*}={\frac {(190\cdot 6.70\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\approx 274\cdot R_{\bigodot }.$ ^[13]

[aaa474_2_653-1] van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.

[gcvs-2] Samus, N. N.; Durlevich, O. V.; et al. (2009), "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)", VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S, 1, Bibcode:2009yCat....102025S.

[mnras162_11-3] Crampton, D.; Lloyd Evans, T. (1973), "Spectroscopic observations of M giant stars at the South Galactic Pole", Monthly Notices of the Royal Astronomical Society, 162: 11–15, Bibcode:1973MNRAS.162...11C, doi:10.1093/mnras/162.1.11.

[aass34_1-4] Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N.

[aaa498_2_627-5] Famaey, B.; et al. (May 2009), "Spectroscopic binaries among Hipparcos M giants. I. Data, orbits, and intrinsic variations", Astronomy and Astrophysics, 498 (2): 627–640, arXiv:0901.0934, Bibcode:2009A&A...498..627F, doi:10.1051/0004-6361/200810698, S2CID 18739721.

[Anderson2012-6] Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.

[mcdonald2017-7] McDonald, I.; Zijlstra, A. A.; Watson, R. A. (15 June 2017), "Fundamental parameters and infrared excesses of Tycho–Gaia stars", Monthly Notices of the Royal Astronomical Society, 471 (1): 770–791, arXiv:1706.02208, Bibcode:2017MNRAS.471..770M, doi:10.1093/mnras/stx1433, eISSN 1365-2966, ISSN 0035-8711.

[SIMBAD-8] "chi Aqr -- Semi-regular pulsating Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-05.

[CDS-9] "/ftp/cats/more/HIP/cdroms/cats", Centre de Données astronomiques de Strasbourg, Strasbourg astronomical Data Center, retrieved 15 October 2022.

[aaa431_773-10] Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.

[mnras331_1_45-12] Koen, Chris; Eyer, Laurent (March 2002), "New periodic variables from the Hipparcos epoch photometry", Monthly Notices of the Royal Astronomical Society, 331 (1): 45–59, arXiv:astro-ph/0112194, Bibcode:2002MNRAS.331...45K, doi:10.1046/j.1365-8711.2002.05150.x, S2CID 10505995.

[mnras400_4_1945-13] Tabur, V.; et al. (December 2009), "Long-term photometry and periods for 261 nearby pulsating M giants", Monthly Notices of the Royal Astronomical Society, 400 (4): 1945–1961, arXiv:0908.3228, Bibcode:2009MNRAS.400.1945T, doi:10.1111/j.1365-2966.2009.15588.x, S2CID 15358380.

[lang2006-14] Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1

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Observation data Epoch J2000 Equinox J2000
Location of χ Aquarii (circled)
Constellation	Aquarius
Right ascension	23^h 16^m 50.93916^s^[1]
Declination	−07° 43′ 35.4023″^[1]
Apparent magnitude (V)	4.75 - 5.10^[2]
Characteristics
Spectral type	M3 III^[3]
U−B color index	+1.60^[4]
B−V color index	+1.60^[4]
Variable type	SRb?^[2]
Astrometry

Radial velocity (R_v)	−13.72 ± 0.86^[5] km/s
Proper motion (μ)	RA: −19.18^[1] mas/yr Dec.: −14.10^[1] mas/yr
Parallax (π)	5.32 ± 0.37 mas^[1]
Distance	610 ± 40 ly (190 ± 10 pc)
Absolute magnitude (M_V)	−1.43^[6]

Details

Radius	142^[7] `R`_☉
Luminosity	2,598^[7] `L`_☉
Surface gravity (log g)	0.128^[7] cgs
Temperature	3,456^[7] K

Other designations
χ Aqr, 92 Aquarii, BD−08 6076, HD 219576, HIP 114939, HR 8850, SAO 146612.^[8]
Database references
SIMBAD	data