From Wikipedia, the free encyclopedia
Star with a brown dwarf companion
HD 221420 (HR 8935; Gliese 4340 ) is a likely
binary star system
[7] in the southern
circumpolar constellation
Octans . It has an
apparent magnitude of 5.81, allowing it to be faintly seen with the
naked eye . The object is relatively close at a distance of 102
light years but is receding with a heliocentric
radial velocity of 26.5
km/s .
HD 221420 has a
stellar classification of G2 IV-V,
[3] indicating a
solar analogue with a
luminosity class intermediate between a
subgiant and a
main sequence star . The object is also extremely
chromospherically inactive .
[3] It has a comparable
mass to the
Sun and a
diameter of 1.95
R ☉ .
[7] It shines with a
luminosity of 4
L ☉
[8] from its
photosphere at an
effective temperature of 5,830
K ,
[9] giving a yellow glow. HD 221420 is younger than the
Sun at 3.65
billion years .
[7] Despite this, the star is already beginning to evolve off the
main sequence . Like most planetary hosts, HD 221420 has a
metallicity over twice of that of the Sun
[7] and spins modestly with a
projected rotational velocity 2.8
km/s .
[11]
There is a mid-
M-dwarf star with a similar proper motion and parallax to HD 221420, which is likely gravitationally bound to it. The two stars are separated by 698
arcseconds , corresponding to a distance of 21,756
AU .
[7]
Planetary system
In a 2019
doppler spectroscopy survey, an
exoplanet was discovered orbiting the star. The planet was originally thought to be a
super Jupiter , having a
minimum mass of 9.7
M J .
[9] However, later observations using
Hipparcos and
Gaia
astrometry found it to be a
brown dwarf with a high-
inclination orbit,
[7]
[10]
[14] revealing a true mass of 23
M J .
[7]
References
^
a
b
c
d Vallenari, A.; et al. (Gaia collaboration) (2023).
"Gaia Data Release 3. Summary of the content and survey properties" . Astronomy and Astrophysics . 674 : A1.
arXiv :
2208.00211 .
Bibcode :
2023A&A...674A...1G .
doi :
10.1051/0004-6361/202243940 .
S2CID
244398875 .
Gaia DR3 record for this source at
VizieR .
^ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics . 355 : L27–L30.
Bibcode :
2000A&A...355L..27H .
ISSN
0004-6361 .
^
a
b
c Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (2 June 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 .
eISSN
1538-3881 .
ISSN
0004-6256 .
^
a
b Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory . 4 : 99–110.
Bibcode :
1966CoLPL...4...99J .
^ Jofré, E.; Petrucci, R.; Saffe, C.; Saker, L.; Artur de la Villarmois, E.; Chavero, C.; Gómez, M.; Mauas, P. J. D. (26 January 2015).
"Stellar parameters and chemical abundances of 223 evolved stars with and without planets" . Astronomy & Astrophysics . 574 : A50.
arXiv :
1410.6422 .
Bibcode :
2015A&A...574A..50J .
doi :
10.1051/0004-6361/201424474 .
eISSN
1432-0746 .
ISSN
0004-6361 .
^ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters . 38 (5): 331–346.
arXiv :
1108.4971 .
Bibcode :
2012AstL...38..331A .
doi :
10.1134/S1063773712050015 .
ISSN
1063-7737 .
S2CID
119257644 .
^
a
b
c
d
e
f
g
h
i
j
k
l Venner, Alexander; Vanderburg, Andrew; Pearce, Logan A. (11 June 2021).
"True Masses of the Long-period Companions to HD 92987 and HD 221420 from Hipparcos–Gaia Astrometry" . The Astronomical Journal . 162 (1): 12.
arXiv :
2104.13941 .
Bibcode :
2021AJ....162...12V .
doi :
10.3847/1538-3881/abf932 .
eISSN
1538-3881 .
ISSN
0004-6256 .
^
a
b
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 Kane, Stephen R.; Dalba, Paul A.; Li, Zhexing; Horch, Elliott P.; Hirsch, Lea A.; Horner, Jonathan; Wittenmyer, Robert A.; Howell, Steve B.; Everett, Mark E.; Butler, R. Paul; Tinney, Christopher G.; Carter, Brad D.; Wright, Duncan J.; Jones, Hugh R. A.; Bailey, Jeremy; O'Toole, Simon J. (5 June 2019).
"Detection of Planetary and Stellar Companions to Neighboring Stars via a Combination of Radial Velocity and Direct Imaging Techniques" . The Astronomical Journal . 157 (6): 252.
arXiv :
1904.12931 .
Bibcode :
2019AJ....157..252K .
doi :
10.3847/1538-3881/ab1ddf .
eISSN
1538-3881 .
^
a
b Li, Yiting; Brandt, Timothy D.; Brandt, G. Mirek; Dupuy, Trent J.; Michalik, Daniel; Jensen-Clem, Rebecca; Zeng, Yunlin; Faherty, Jacqueline; Mitra, Elena L. (26 November 2021).
"Precise Masses and Orbits for Nine Radial-velocity Exoplanets" . The Astronomical Journal . 162 (6): 266.
arXiv :
2109.10422 .
Bibcode :
2021AJ....162..266L .
doi :
10.3847/1538-3881/ac27ab .
eISSN
1538-3881 .
ISSN
0004-6256 .
^
a
b Valenti, Jeff A.; Fischer, Debra A. (July 2005).
"Spectroscopic Properties of Cool Stars (SPOCS). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs" . The Astrophysical Journal Supplement Series . 159 (1): 141–166.
Bibcode :
2005ApJS..159..141V .
doi :
10.1086/430500 .
eISSN
1538-4365 .
ISSN
0067-0049 .
^ Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino . 1 .
Bibcode :
1879RNAO....1.....G .
^
"HR 8935" .
SIMBAD .
Centre de données astronomiques de Strasbourg . Retrieved July 15, 2022 .
^ Feng, Fabo; Butler, R. Paul; et al. (August 2022).
"3D Selection of 167 Substellar Companions to Nearby Stars" .
The Astrophysical Journal Supplement Series . 262 (21): 21.
arXiv :
2208.12720 .
Bibcode :
2022ApJS..262...21F .
doi :
10.3847/1538-4365/ac7e57 .
S2CID
251864022 .