HD 7924

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HD 7924
HD 7924 in Cassiopeia constellation map.png
Position of star HD 7924 in the constellation Cassiopeia
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Cassiopeia
Right ascension 01h 21m 59.1132s [1]
Declination +76° 42′ 37.0373″ [1]
Apparent magnitude  (V)7.167 [2]
Characteristics
Evolutionary stage main sequence
Spectral type K0.5V [3]
Apparent magnitude  (B)8.005 [2]
Apparent magnitude  (J)5.618 [4]
Apparent magnitude  (H)5.231 [4]
Apparent magnitude  (K)5.159 [4]
B−V color index +0.826±0.006 [5]
Astrometry
Radial velocity (Rv)−22.70±0.15 [1]  km/s
Proper motion (μ)RA: −34.643±0.041 [1]   mas/yr
Dec.: −32.660±0.038 [1]   mas/yr
Parallax (π)58.8216 ± 0.0249  mas [1]
Distance 55.45 ± 0.02  ly
(17.001 ± 0.007  pc)
Absolute magnitude  (MV)6.04 [5]
Details [6]
Mass 0.81±0.01  M☉
Radius 0.74±0.01  R☉
Luminosity 0.364±0.001  L☉
Surface gravity (log g)4.6±0.01  cgs
Temperature 5,216±13  K
Metallicity [Fe/H]−0.15±0.03  dex
Rotational velocity (v sin i)0.9 [7]  km/s
Age 3.0±1.8  Gyr
Other designations
BD+75°58, GJ  56.5, HD  7924, HIP  6379, SAO  4386, PPM  4675, TYC  4494-1346-1, GCRV  766, GSC  04494-01396, 2MASS J01215911+7642372 [8]
Database references
SIMBAD data
Exoplanet Archive data
ARICNS data
Extrasolar Planets
Encyclopaedia 		data

HD 7924 is a single [9] star located 55.5 [1]   light years away from the Sun in the northern constellation of Cassiopeia, near the northern constellation border with Cepheus. It has an orange hue and is only visible by means of binoculars or a telescope due to a low apparent visual magnitude of 7.167. [2] The star is drifting closer to the Sun with a radial velocity of –22.7 km/s, [1] and is expected to approach to within 9.3 light-years in around 711,700 years. [10]

Contents

This is a K-type main-sequence star with a stellar classification of K0.5V. [3] Low-level chromospheric activity has been detected, with the star showing spots and an activity cycle. [9] The star is about three [6]  billion years old and is spinning with a projected rotational velocity of just 0.9 km/s. [7] It has 81% of the mass of the Sun and 74% of the Sun's radius. The metal content is about seven-tenths as much as the Sun. It is radiating 36.4% of the luminosity of the Sun from its photosphere at an effective temperature of 5,216 K. [6]

Planetary system

In 2009, a super-Earth exoplanet was found in orbit around the star. [11] In 2015, two more planets were discovered, and the mass of the original planet was revised downwards slightly. [12] [9] It is possible that planets c and d are in the 8:5 mean motion resonance. [13] All of the planets lie inside the star's habitable zone. [9]

The HD 7924 planetary system [9]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥ 8.68±0.52  M🜨 0.05664±0.000685.39792±0.000250.058 +0.056
−0.040		——
c≥ 7.86±0.72  M🜨 0.1134±0.001415.299±0.00330.098 +0.096
−0.069		——
d≥ 6.44±0.79  M🜨 0.1551±0.001924.451±0.0160.21 +0.13
−0.12		——

See also

Related Research Articles

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<span class="mw-page-title-main">HD 187123</span> Star in the constellation Cygnus

HD 187123 is a single, yellow-hued star with two exoplanetary companions in the northern constellation of Cygnus. It has an apparent visual magnitude of 7.83, making it an 8th magnitude star that is too faint to be visible with the naked eye. However, it should be easy target with binoculars or small telescope. The system is located at a distance of 150 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −17 km/s.

<span class="mw-page-title-main">HD 192263</span> Star in the constellation Aquila

HD 192263 is an 8th magnitude star about 64 light years away in the constellation of Aquila. The spectral type of the star is K2V, meaning that it is an orange dwarf, a type of star somewhat cooler and less luminous than the Sun. It is not visible to the unaided eye, but with good binoculars or small telescope it should be easy to spot.

HD 210277 is a single star in the equatorial constellation of Aquarius. It has an apparent visual magnitude of 6.54, which makes it a challenge to view with the naked eye, but it is easily visible in binoculars. The star is located at a distance of 69.5 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −20.9 km/s.

<span class="mw-page-title-main">HD 108874</span> Star in the constellation Coma Berenices

HD 108874 is a yellow dwarf star in the constellation of Coma Berenices. It is 195 light years from Earth and has two extrasolar planets that are possibly in a 9:2 orbital resonance.

HD 142 is a wide binary star system in the southern constellation of Phoenix. The main component has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.7. The system is located at a distance of 85.5 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of +6 km/s.

HD 1237 is a binary star system approximately 57 light-years away in the constellation of Hydrus.

HD 4308 is a single star in the southern constellation of Tucana. It has a yellow hue and is a challenge to view with the naked eye even under good seeing conditions, having an apparent visual magnitude of 6.54. This object is located at a distance of 72 light years, as determined from parallax measurements. It is a population II star and is considered to be a member of the thick disk. The star is receding from the Sun with a radial velocity of +95 km/s.

HD 222582 is a multiple star system in the equatorial constellation of Aquarius. It is invisible to the naked eye with an apparent visual magnitude of 7.7, but can be viewed with binoculars or a small telescope. The system is located at a distance of 138 light years from the Sun based on parallax, and it is drifting further away with a radial velocity of +12 km/s. It is located close enough to the ecliptic that it is subject to lunar occultations.

HD 17156, named Nushagak by the IAU, is a yellow subgiant star approximately 255 light-years away in the constellation of Cassiopeia. The apparent magnitude is 8.17, which means it is not visible to the naked eye but can be seen with good binoculars. A search for a binary companion star using adaptive optics at the MMT Observatory was negative.

HD 154857 is a star with two exoplanetary companions in the southern constellation of Ara. It is too dim to be visible with the naked eye having an apparent visual magnitude of 7.25. The star is located at a distance of 207 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of +28 km/s.

HD 37605 is a star in the equatorial constellation of Orion. It is orange in hue but is too faint to be visible to the naked eye, having an apparent visual magnitude of 8.67. Parallax measurements yield a distance estimate of 153 light years from the Sun. It has a high proper motion and is drifting closer with a radial velocity of −22 km/s.

HD 111232 is a star in the southern constellation of Musca. It is too faint to be visible with the naked eye, having an apparent visual magnitude of 7.59. The distance to this star is 94.5 light years based on parallax. It is drifting away from the Sun with a radial velocity of +104 km/s, having come to within 14.1 light-years some 264,700 years ago. The absolute magnitude of this star is 5.25, indicating it would have been visible to the naked eye at that time.

HD 162020 is a star in the southern constellation of Scorpius with a likely red dwarf companion. It has an apparent visual magnitude of 9.10, which is too faint to be visible to the naked eye. The distance to this system is 101 light years based on stellar parallax. It is drifting closer to the Sun with a radial velocity of −27 km/s, and is predicted to come to within ~18 light-years in 1.1 million years.

HD 131664 is an 8th magnitude star in the southern constellation of Apus with an orbiting brown dwarf or stellar companion. Parallax measurements by the Gaia space observatory provide an estimated distance of 172.5 light years from the Earth. The system is moving further away with a baseline heliocentric radial velocity of +35 km/s.

HD 204313 is a star with two and possibly three exoplanetary companions in the southern constellation of Capricornus. With an apparent magnitude of 7.99, it is an eighth magnitude star that is too faint to be readily visible to the naked eye. The star is located at a distance of 157 light years from the Sun based on parallax measurements, but it is drifting closer with a radial velocity of −10 km/s.

HD 34445 is a star with multiple exoplanetary companions in the equatorial constellation of Orion. With an apparent visual magnitude of 7.31, it is a 7th magnitude star that is too dim to be readily visible to the naked eye. The system is located at a distance of 150.5 light years from the Sun based on parallax measurements, but is drifting closer with a high radial velocity of −79 km/s. It is expected to draw as close as 57.5 light-years in ~492,000 years.

HD 129445 is a G-type star found in the Circinus constellation located 219 light-years away from the Sun based on parallax. It is invisible to the naked eye with an apparent visual magnitude of 8.80. The star was observed by the Magellan Planet Search Program due to its absolute visual magnitude and high metallicity. The Magellan program conducted 17 doppler velocity measurements, which spans a full orbital period. The results led the program to detect a planet dubbed HD 129445 b. In 2023, the inclination and true mass of HD 129445 b were determined via astrometry.

HD 164604 is a single star in the southern constellation of Sagittarius constellation. It has the proper name Pincoya, as selected in the NameExoWorlds campaign by Chile, during the 100th anniversary of the IAU. Pincoya is a female water spirit from southern Chilean mythology who is said to bring drowned sailors to the Caleuche so that they can live in the afterlife. A 2015 survey ruled out the existence of any additional stellar companions at projected distances from 13 to 340 astronomical units. It is known to host a single super-Jupiter exoplanet.

HD 146389, is a star with a yellow-white hue in the northern constellation of Hercules. The star was given the formal name Irena by the International Astronomical Union in January 2020. It is invisible to the naked eye with an apparent visual magnitude of 9.4 The star is located at a distance of approximately 446 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −9 km/s. The star is known to host one exoplanet, designated WASP-38b or formally named 'Iztok'.

References

  1. 1 2 3 4 5 6 7 8 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.
  2. 1 2 3 Høg, E.; et al. (2000). The Tycho-2 catalogue of the 2.5 million brightest stars. pp. L27. Bibcode:2000A&A...355L..27H. doi:10.1888/0333750888/2862. ISBN   978-0333750889.{{cite book}}: |journal= ignored (help)
  3. 1 2 von Braun, Kaspar; et al. (2014). "Stellar diameters and temperatures - V. 11 newly characterized exoplanet host stars". Monthly Notices of the Royal Astronomical Society. 438 (3): 2413–2425. arXiv: 1312.1792 . Bibcode:2014MNRAS.438.2413V. doi:10.1093/mnras/stt2360.
  4. 1 2 3 Cutri, R. M.; et al. (June 2003). 2MASS All Sky Catalog of point sources. NASA/IPAC. Bibcode:2003tmc..book.....C.
  5. 1 2 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.
  6. 1 2 3 Bonfanti, A.; et al. (2015). "Revising the ages of planet-hosting stars". Astronomy and Astrophysics. 575. A18. arXiv: 1411.4302 . Bibcode:2015A&A...575A..18B. doi:10.1051/0004-6361/201424951. S2CID   54555839.
  7. 1 2 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.
  8. ↑ "HD 7924". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2019-11-07.
  9. 1 2 3 4 5 Fulton, Benjamin J.; et al. (2015). "Three Super-Earths Orbiting HD 7924". The Astrophysical Journal. 805 (2): 175. arXiv: 1504.06629 . Bibcode:2015ApJ...805..175F. doi:10.1088/0004-637X/805/2/175. S2CID   7969255.
  10. ↑ Bailer-Jones, C.A.L.; et al. (2018). "New stellar encounters discovered in the second Gaia data release". Astronomy & Astrophysics. 616: A37. arXiv: 1805.07581 . Bibcode:2018A&A...616A..37B. doi:10.1051/0004-6361/201833456. S2CID   56269929.
  11. ↑ Howard, Andrew W.; et al. (2009). "The NASA-UC Eta-Earth Program. I. A Super-Earth Orbiting HD 7924". The Astrophysical Journal. 696 (1): 75–83. arXiv: 0901.4394 . Bibcode:2009ApJ...696...75H. doi:10.1088/0004-637X/696/1/75. S2CID   1415310.
  12. ↑ Sanders, Robert (April 28, 2015). "Robotic telescope discovers three super-Earth planetary neighbors". Berkeley News. UC Berkeley. Retrieved 2019-11-07.
  13. ↑ Kane, Stephen R. (2016). "Resolving Close Encounters: Stability in the HD 5319 and HD 7924 Planetary Systems". The Astrophysical Journal. 799 (1). 105. arXiv: 1411.5374 . Bibcode:2016ApJ...830..105K. doi: 10.3847/0004-637X/830/2/105 . S2CID   118542104.
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