Star in the constellation Aquarius
Lambda Aquarii , informally known as Hydor (),
[11]
[12] is a
variable star in the
equatorial
constellation of
Aquarius . The name is
Latinized from the
Bayer designation λ Aquarii. The
apparent visual magnitude of this star ranges from 3.57 down to 3.80,
[3] which is bright enough to be visible with the naked eye. It lies just 0.39 degrees south of the ecliptic
[13] and so is subject to
lunar occultations .
[14]
[15] The star is eclipsed by the sun from about 1-4 March;
[16] thus the star can be viewed the whole night, crossing the sky, in early September, in the current epoch. Lambda Aquarii is located at a distance of approximately 310
light-years (95
pc ) from the
Sun based on
parallax ,
[1] but is drifting closer with a
radial velocity of −10.5 km/s.
[6]
A
visual band
light curve for Lambda Aquarii, plotted from data published by Tabur et al. (2009).
[17] The inset plot shows the same data folded with a period of 24.5 days, after a linear trend had been removed.
The
stellar classification of Lambda Aquarii is M2.5 IIIa Fe–1 ,
[5] indicating this is an aging
red giant star with an underabundance of iron showing in its
spectrum . This star is on the
asymptotic giant branch and is generating energy through the nuclear fusion of hydrogen and helium along concentric shells surrounding an inert core of carbon and oxygen.
[4] With 3.6
[9] times the
mass of the Sun , it has expanded to 44
[1] times the
Sun's radius . It is classified as
slow irregular variable and pulsation periods of 24.5, 32.0, and 49.5 days have been identified.
[17] On average, it is radiating nearly 700
[1] times the
luminosity of the Sun from the
photosphere at an
effective temperature of 3,835 K.
[9]
Naming
Hydor is from Greek Ὕδωρ "water", a name given by
Proclus , according to
Richard Hinckley Allen . Another Greek name for the star is Ekkhysis , from εκχυσις "outpouring".
[12]
In
Chinese , 壘壁陣 (Lěi Bì Zhèn ), meaning
Line of Ramparts , refers to an asterism consisting of λ Aquarii,
κ Capricorni ,
ε Capricorni ,
γ Capricorni ,
δ Capricorni ,
ι Aquarii ,
σ Aquarii ,
φ Aquarii ,
27 Piscium ,
29 Piscium ,
33 Piscium and
30 Piscium .
[18] Consequently, λ Aquarii itself is 壘壁陣七 (Lěi Bì Zhèn qī , English: the Seventh Star of Line of Ramparts .)
[19]
References
^
a
b
c
d
e
f
g
h
i
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 .
^
a
b
c Gutierrez-Moreno, Adelina; et al. (1966). "A System of photometric standards". Publ. Dept. Astron. Univ. Chile . 1 . Publicaciones Universidad de Chile, Department de Astronomy: 1–17.
Bibcode :
1966PDAUC...1....1G .
^
a
b
c Samus, N. N.; Kazarovets, E. V.; et al. (2017).
"General Catalogue of Variable Stars" . Astronomy Reports . 61 (1) (5.1 ed.): 80–88.
Bibcode :
2017ARep...61...80S .
doi :
10.1134/S1063772917010085 .
S2CID
125853869 . Retrieved 2019-11-23 .
^
a
b Lebzelter, T.; Hron, J. (January 2008).
"BRITE stars on the AGB" . Communications in Asteroseismology . 152 : 178–181.
Bibcode :
2008CoAst.152..178L .
doi :
10.1553/cia152s178 .
^
a
b 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.
arXiv :
0806.2878 .
Bibcode :
2008MNRAS.389..869E .
doi :
10.1111/j.1365-2966.2008.13596.x .
S2CID
14878976 .
^
a
b 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 .
^
Brown, A. G. A. ; et al. (Gaia collaboration) (2021).
"Gaia Early Data Release 3: Summary of the contents and survey properties" .
Astronomy & Astrophysics . 649 : A1.
arXiv :
2012.01533 .
Bibcode :
2021A&A...649A...1G .
doi :
10.1051/0004-6361/202039657 .
S2CID
227254300 . (Erratum:
doi :
10.1051/0004-6361/202039657e ) .
Gaia EDR3 record for this source at
VizieR .
^
a
b Dupree, A. K.; Li, Timothy Q.; Smith, Graeme H. (October 2007). "Hubble Space Telescope Observations of Chromospheres in Metal-Deficient Field Giants". The Astronomical Journal . 134 (4): 1348–1359.
arXiv :
0709.1709 .
Bibcode :
2007AJ....134.1348D .
doi :
10.1086/520925 .
S2CID
14481140 .
^
a
b
c
d Tsuji, Takashi (May 2007). Kupka, F.; Roxburgh, I.; Chan, K. (eds.). "Convection in Astrophysics, Proceedings of IAU Symposium #239 held 21-25 August, 2006 in Prague, Czech Republic". Proceedings of the International Astronomical Union . 2 : 307–310.
arXiv :
astro-ph/0610180 .
Bibcode :
2007IAUS..239..307T .
doi :
10.1017/S1743921307000622 .
S2CID
119362842 . Isotopic abundances of Carbon and Oxygen in Oxygen-rich giant stars.
^
"* lam Aqr" .
SIMBAD .
Centre de données astronomiques de Strasbourg . Retrieved 2012-07-01 .
^
Kaler, James B.
"Hydor" . STARS . Retrieved 2017-08-17 .
^
a
b
Allen, Richard Hinckey .
"Star Names: Their Lore and Meaning" . Retrieved 2017-08-17 .
^
John Pratt's stars re-publication by Dr J.P. Pratt (Doctor of Astronomy, University of Arizona) of sidereal coordinate data. Note: possibly a non-book published source.
^ Schmidtke, P. C.; Africano, J. L. (January 2011). "KPNO Lunar Occultation Summary. III". The Astronomical Journal . 141 (1): 7.
Bibcode :
2011AJ....141...10S .
doi :
10.1088/0004-6256/141/1/10 .
S2CID
120313180 . 10.
^
Nather, R. Edward ; et al. (June 1970). "The Angular Diameter of Lambda Aquarii". Astrophysical Journal . 160 : L181.
Bibcode :
1970ApJ...160L.181N .
doi :
10.1086/180555 .
^ Ford, Dominic.
"In-The-Sky.org Planetarium" . Retrieved 2021-06-07 .
^
a
b 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 .
^ (in Chinese) 中國星座神話 , written by 陳久金. Published by 台灣書房出版有限公司, 2005,
ISBN
978-986-7332-25-7 .
^ (in Chinese)
AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 7 日
External links