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Orange-hued giant star in the constellation Aquarius
99 Aquarii (abbreviated 99 Aqr ) is a
star in the
equatorial
constellation of
Aquarius . 99 Aquarii is the
Flamsteed designation , although it also bears the
Bayer designation b2 Aquarii . It is visible to the naked eye with an
apparent visual magnitude of 4.38;
[2] according to the
Bortle Dark-Sky Scale this is bright enough to be seen even from city skies under ideal viewing conditions. Based upon
parallax measurements, the distance to this star is around 283
light-years (87
parsecs ).
[1]
This is a
giant star with a
stellar classification of K4 III.
[3] It is a suspected
variable star that apparently ranges in magnitude between 4.35 and 4.45.
[4] The measured
angular diameter of this star is 3.55 ± 0.21
mas .
[9] At the estimated distance of Delta Ophiuchi,
[1] this yields a physical size of about 33 times the
radius of the Sun .
[6] The
outer atmosphere has an
effective temperature of 3980 K,
[7] giving it the orange-hued glow of a cool,
K-type star .
[10]
This star was a candidate member of the
Ursa Major Moving Group based on the work of American astronomer
Nancy Roman , but this membership is now in question.
[11]
References
^
a
b
c
d
e
f
g 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
c
d Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants.",
Monthly Notices of the Royal Astronomical Society , 172 (3): 667–679,
Bibcode :
1975MNRAS.172..667J ,
doi :
10.1093/mnras/172.3.667 .
^
a
b Houk, Nancy (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 .
^
a
b Samus, N. N.; et al. (March 2012),
"NSV 14554" , General Catalog of Variable Stars , retrieved 2012-07-12 .
^ Wilson, Ralph Elmer (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication , Washington:
Carnegie Institution of Washington ,
Bibcode :
1953GCRV..C......0W .
^
a
b Lang, Kenneth R. (2006),
Astrophysical formulae , Astronomy and astrophysics library, vol. 1 (3rd ed.),
Birkhäuser ,
ISBN
3-540-29692-1 . . The radius (R* ) is given by:
2
⋅
R
∗
=
(
87
⋅
3.55
⋅
10
−
3
)
AU
0.0046491
AU
/
R
⨀
≈
66
⋅
R
⨀
{\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(87\cdot 3.55\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 66\cdot R_{\bigodot }\end{aligned}}}
^
a
b
c
d McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", Astrophysical Journal Supplement Series , 74 : 1075–1128,
Bibcode :
1990ApJS...74.1075M ,
doi :
10.1086/191527 .
^
"* 99 Aqr" .
SIMBAD .
Centre de données astronomiques de Strasbourg . Retrieved 2012-07-11 .
^ 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 .
^
"The Colour of Stars" , Australia Telescope, Outreach and Education ,
Commonwealth Scientific and Industrial Research Organisation , December 21, 2004, archived from
the original on March 18, 2012, retrieved 2012-01-16 .
^ Chupina, N. V.; Reva, V. G.; Vereshchagin, S. V. (June 2006), "Kinematic structure of the corona of the Ursa Major flow found using proper motions and radial velocities of single stars", Astronomy and Astrophysics , 451 (3): 909–916,
Bibcode :
2006A&A...451..909C ,
doi :
10.1051/0004-6361:20054009 . See table 7.
External links