Binary star system in the constellation of Cancer
HD 72945 & HD 72946
Observation data
Epoch
J2000.0
Equinox
J2000.0
Constellation
Cancer
HD 72945
Right ascension
08h 35m 50.978s
[1]
Declination
06° 37′ 12.77″
[1]
Apparent magnitude (V)
5.91
[2]
HD 72946
Right ascension
08h 35m 51.267s
[3]
Declination
06° 37′ 21.95″
[3]
Apparent magnitude (V)
7.25
[2]
Characteristics
HD 72945
Evolutionary stage
Main sequence
[4]
Spectral type
F8 V
[5]
B−V
color index
0.530± 0.007
[2]
HD 72946
Spectral type
G5V
[6]
B−V
color index
0.710± 0.015
[2]
Astrometry HD 72945
Radial velocity (Rv ) 26.61± 0.15
[7] km/s
Proper motion (μ)
RA: −130.308
mas /
yr
[1]
Dec.: −133.119
mas /
yr
[1]
Parallax (π) 38.4212 ± 0.1515
mas
[1]
Distance 84.9 ± 0.3
ly (26.0 ± 0.1
pc )
Absolute magnitude (MV ) 3.91
[2] HD 72946
Radial velocity (Rv ) 28.75± 0.14
[8] km/s
Proper motion (μ)
RA: −136.593
mas /
yr
[3]
Dec.: −137.148
mas /
yr
[3]
Parallax (π) 38.9809 ± 0.0412
mas
[3]
Distance 83.67 ± 0.09
ly (25.65 ± 0.03
pc )
Absolute magnitude (MV ) 5.16
[2]
Orbit
[7] Primary HD 72945 A
Period (P) 14.2995± 0.0001 d
Semi-major axis (a) ≥4.07 ± 0.05 Gm (5.850 ± 0.072 R ☉ )
Eccentricity (e) 0.332± 0.008
Periastron
epoch (T) 2,446,781.30± 0.12
JD
Argument of periastron (ω) (secondary)227.1± 3.0°
Semi-amplitude (K1 ) (primary)21.95± 0.15 km/s
Details HD 72945
Mass 1.245± 0.030
[9]
M ☉
Radius 1.358
[10]
R ☉
Luminosity 2.372
[10]
L ☉
Surface gravity (log g ) 4.32
[11]
cgs
Temperature 6,222
[11]
K
Metallicity [Fe/H]0.05
[11]
dex
Rotational velocity (v sin i ) 7.1
[11] km/s
Age 1.584± 0.952
[9]
Gyr HD 72946
Mass 1.02± 0.04
[12]
M ☉
Radius 0.97± 0.02
[12]
R ☉ Luminosity 0.84
[2]
L ☉
Surface gravity (log g ) 4.69
[13]
cgs
Temperature 5,670
[12]
K
Metallicity [Fe/H]0.16
[12]
dex
Rotational velocity (v sin i ) 4.14
[9] km/s
Age 1.9+0.6 −0.5
[6]
Gyr
Other designations HD 72945 : Boss 2285
[16] ,
GC 11781,
HIP 42172,
HR 3395,
SAO 116929,
PPM 154707,
NLTT 19856
[14] HD 72946 : Boss 2286
[16] ,
GC 16412,
HIP 42173,
HR 3396,
SAO 116931,
PPM 154708,
NLTT 19851
[15]
Database references
SIMBAD
HD 72945
HD 72946
HD 72945 and HD 72946 form a co-moving
star system in the northern
constellation of
Cancer .
[17] HD 72945 is a
binary star that is dimly visible to the naked eye as a point of light with an
apparent visual magnitude of 5.91.
[2] At an
angular separation of 10.10
″ (as of 2020)
[18] is the fainter companion star HD 72946 at magnitude 7.25.
[2] It is being orbited by a
brown dwarf .
[9] The system as a whole is located at a distance of approximately 84
light years from the
Sun based on
parallax measurements.
[1]
[3]
The discovery of this
double star was announced by
F. G. W. Struve in 1782, and later given the
discovery code STF 1245.
[18] Their
common proper motion was confirmed by
A. van Maanen in 1916, and this suggested they are physically associated.
[16] The
projected separation of the two systems is 258.9
AU .
[19] Based on
astrometric measurements from the
Gaia spacecraft , the
semimajor axis of this system is 200+52 −41
AU .
[6] Assuming they are
gravitationally bound , they would have an
orbital period of around 2,500 years.
[20]
There is an additional candidate stellar companion at an angular separation of ~130″ , which would make this a four star system. (This object has the
2MASS designation J08354678+0635294.)
[9] Three additional faint companions detected by Struve are most likely background stars.
[7]
HD 72945
The binary nature of HD 72945 was announced in 1919 by
A. H. Joy and
G. Abetti at the
Mount Wilson Observatory . Observed variations in the
radial velocity of the primary component inferred an orbiting stellar companion.
[16] This is a single-lined
spectroscopic binary system with a
period of 14.3 days and an
orbital eccentricity of 0.33.
[7] The minimum value for the semimajor axis is only 5.9 times the
radius of the Sun , although the actual value is uncertain because the
orbital inclination is unknown.
[7]
The visible component of this system has a
stellar classification of F8 V,
[5] matching an ordinary
F-type main-sequence star . It has 1.25
[9] times the
mass of the Sun and 1.4
[10] times the
Sun's radius . The star is radiating 2.4
[10] times the
luminosity of the Sun from its
photosphere at an
effective temperature of 6,222 K.
[11] It has an estimated age of approximately 1.6 billion years.
[9] The derived minimum mass for the secondary component is 0.34 M ☉ .
[9]
HD 72946
This is a
G-type main-sequence star with a class of G5V.
[6] It has about the same size and mass as the Sun.
[12] However, the star is slightly more active than the Sun, and thus probably younger.
[6] It is
metal-rich , showing a higher abundance of elements other than hydrogen and helium compared to the Sun.
[21]
In 2016, a candidate
brown dwarf companion in orbit around HD 72946 was announced. It was discovered based on radial velocity monitoring over a twenty-year period.
[22] The companion was confirmed in 2020.
[9] It has a classification of
L5.0± 1.5 , a derived temperature of 1,700± 90 K , and a mass near the
hydrogen-burning limit .
[6] The orbit lies just outside the
ice line of the host star, with a semimajor axis of about 6.5 AU .
[9] It is orbiting with a period of 16 years
[6] and an eccentricity of 0.498.
[23]
References
^
a
b
c
d
e
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
c
d
e
f
g
h
i 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
e
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 Abt, Helmut A. (December 23, 2008), "Mk Classifications of Spectroscopic Binaries", The Astrophysical Journal Supplement Series , 180 (1): 117–118,
Bibcode :
2009ApJS..180..117A ,
doi :
10.1088/0067-0049/180/1/117 ,
eISSN
1538-4365 ,
ISSN
0067-0049 .
^
a
b
c
d
e
f
g
h Brandt, G. Mirek; et al. (December 2021), "Improved Dynamical Masses for Six Brown Dwarf Companions Using Hipparcos and Gaia EDR3", The Astronomical Journal , 162 (6): 28,
arXiv :
2109.07525 ,
Bibcode :
2021AJ....162..301B ,
doi :
10.3847/1538-3881/ac273e ,
S2CID
237532125 , 301.
^
a
b
c
d
e Duquennoy, A.; Mayor, M. (1991), "Multiplicity among solar-type stars in the solar neighbourhood. II – Distribution of the orbital elements in an unbiased sample", Astronomy & Astrophysics , 248 (2): 485–524,
Bibcode :
1991A&A...248..485D .
^
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
d
e
f
g
h
i
j Maire, A. -L.; et al. (January 2020), "A dusty benchmark brown dwarf near the ice line of HD 72946", Astronomy & Astrophysics , 633 : 10,
arXiv :
1912.02565 ,
Bibcode :
2020A&A...633L...2M ,
doi :
10.1051/0004-6361/201937134 ,
S2CID
208637214 , L2.
^
a
b
c
d Schofield, Mathew; et al. (2019), "The Asteroseismic Target List for Solar-like Oscillators Observed in 2 minute Cadence with the Transiting Exoplanet Survey Satellite", The Astrophysical Journal Supplement Series , 241 (1): 12,
arXiv :
1901.10148 ,
Bibcode :
2019ApJS..241...12S ,
doi :
10.3847/1538-4365/ab04f5 ,
S2CID
119481586 .
^
a
b
c
d
e Luck, R. Earle (January 2017), "Abundances in the Local Region II: F, G, and K Dwarfs and Subgiants", The Astronomical Journal , 153 (1): 19,
arXiv :
1611.02897 ,
Bibcode :
2017AJ....153...21L ,
doi :
10.3847/1538-3881/153/1/21 ,
S2CID
119511744 , 21.
^
a
b
c
d
e Hirsch, Lea A.; et al. (2021), "Understanding the Impacts of Stellar Companions on Planet Formation and Evolution: A Survey of Stellar and Planetary Companions within 25 pc",
The Astronomical Journal , 161 (3): 134,
arXiv :
2012.09190 ,
Bibcode :
2021AJ....161..134H ,
doi :
10.3847/1538-3881/abd639 ,
S2CID
229297873 .
^ Gray, R. O.; et al. (2003), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I", The Astronomical Journal , 126 (4): 2048,
arXiv :
astro-ph/0308182 ,
Bibcode :
2003AJ....126.2048G ,
doi :
10.1086/378365 ,
S2CID
119417105 .
^
a
b
"HD 72945" ,
SIMBAD ,
Centre de données astronomiques de Strasbourg , retrieved 2022-05-31 .
^
a
b
"HD 72946" ,
SIMBAD ,
Centre de données astronomiques de Strasbourg , retrieved 2022-05-31 .
^
a
b
c
d Joy, A. H.; Abetti, G. (December 1919), "The orbit of the spectroscopic binary Boss 2285", Astrophysical Journal , 50 : 391–393,
Bibcode :
1919ApJ....50..391J ,
doi :
10.1086/142515 .
^ Sinnott, Roger W.; Perryman, Michael A. C. (1997), Millennium Star Atlas , vol. 2, Sky Publishing Corporation and the European Space Agency, p. 761,
ISBN
0-933346-83-2 .
^
a
b Mason, B. D.; et al. (2014),
"The Washington Visual Double Star Catalog" , The Astronomical Journal , 122 (6): 3466–71,
Bibcode :
2001AJ....122.3466M ,
doi :
10.1086/323920 .
^ Tokovinin, A.; Kiyaeva, O. (February 2016), "Eccentricity distribution of wide binaries", Monthly Notices of the Royal Astronomical Society , 456 (2): 2070−2079,
arXiv :
1512.00278 ,
Bibcode :
2016MNRAS.456.2070T ,
doi :
10.1093/mnras/stv2825 ,
S2CID
1615080 .
^ Tokovinin, Andrei (2014), "From Binaries to Multiples. II. Hierarchical Multiplicity of F and G Dwarfs", The Astronomical Journal , 147 (4): 87,
arXiv :
1401.6827 ,
Bibcode :
2014AJ....147...87T ,
doi :
10.1088/0004-6256/147/4/87 ,
S2CID
56066740 .
^ Feltzing, S.; Gustafsson, B. (April 1998), "Abundances in metal-rich stars. Detailed abundance analysis of 47 G and K dwarf stars with [Me/H] > 0.10 dex", Astronomy and Astrophysics Supplement , 129 : 237–266,
arXiv :
astro-ph/9710315 ,
Bibcode :
1998A&AS..129..237F ,
doi :
10.1051/aas:1998400 ,
S2CID
14419843 .
^ Bouchy, F.; et al. (January 2016), "The SOPHIE search for northern extrasolar planets. VIII. Follow-up of ELODIE candidates: long-period brown-dwarf companions", Astronomy & Astrophysics , 585 : 8,
arXiv :
1511.08397 ,
Bibcode :
2016A&A...585A..46B ,
doi :
10.1051/0004-6361/201526347 ,
S2CID
55950304 , A46.
^
a
b Balmer, W.O.; et al. (2023).
"VLTI/GRAVITY Observations and Characterization of the Brown Dwarf Companion HD 72946 B" . The Astrophysical Journal . 956 (2): 24.
arXiv :
2309.04403 .
Bibcode :
2023ApJ...956...99B .
doi :
10.3847/1538-4357/acf761 . 99.