HR 8832

Database links to HR 8832

Star HR 8832
Search card for HR 8832 or HD 219134 (marked with a circle) in the constellation Kassiopeia
AladinLite
Observation dates equinox :  J2000.0 , epoch : J2000.0
Constellation	Cassiopeia
Right ascension	23 h 13 m 16.98 s
declination	+ 57 ° 10 ′ 6.1 ″
Apparent brightness	5,570 likes
Typing
Known exoplanets	6th
B − V color index	+0.983
U − B color index	+0.902
Spectral class	K3V
Astrometry
Radial velocity	−18.83 ± 0.07 km / s
parallax	152.76 ± 0.29  mas
distance	21.35 ± 0.04  ly 6.55 ± 0.01  pc
Visual absolute brightness M vis	6.50 likes
Proper movement
Rec. Share:	109.8985 ± 2.90  mas / a
Dec. portion:	−03.1986 ± 2.20  mas / a
Physical Properties
Dimensions	0.794   +0.037−0.022 M ☉
radius	0.80 ± 0.04  R ☉
Luminosity	0.28  L ☉
Effective temperature	4,710  K
Metallicity [Fe / H]	+0.20
Rotation time	22.83 d
Age	~ 12.46 billion  a
Other names and catalog entries
Bonn survey BD + 56 ° 2966 Bright Star Catalog HR 8832 [1] Henry Draper Catalog HD 219134 [2] Gliese catalog FY 892 [3] Hipparcos catalog HIP 114622 [4] SAO catalog SAO 35236 [5] Tycho catalog TYC 4006-1866-1 [6] 2MASS catalog 2MASS J20450949-3120266 [7] Other names Bradley 3077, FK5 875, GCTP 5616.00, LFT 1767, LHS 71

HR 8832 ( HD 219134 , historical and Bradley 3077 ) is an orange main sequence star of spectral type K in the constellation Cassiopeia , of about 21 light-years from the sun away. The star has a planetary system with up to six exoplanets .

With an apparent brightness of approximately the 6th size , HR 8832 is also visible to the naked eye under good visibility conditions, with a moonless night sky and no light pollution . It is located east of the memorable sky W , which is formed by the main stars of the constellation Cassiopeia.

properties

HR 8832 is smaller and lower in mass than the sun and has about 80% of the solar mass or the solar radius . A variability of the star has been suggested in the past . The rotation period of HR 8832 is approximately 23 days.

Planetary system

The star near the Sun was examined for the presence of orbiting planets as early as the 1990s through precise measurements of the radial velocity . The investigations carried out at the time ruled out the existence of planets with more than 0.7 Jupiter masses within an orbital radius of less than 5 AU . HR 8832 was also one of the 100 most important target stars of the mission Terrestrial Planet Finder of NASA , but has been postponed several times and finally in 2011 deleted.

On July 30, 2015, an astronomical team around Fatemeh Motalebi published the discovery of four exoplanets around HR 8832 based on measurement data from the HARPS-N spectrograph at the Telescopio Nazionale Galileo on La Palma . A second team of astronomers headed by Steven S. Vogt published the discovery of six planets a little later, in September 2015, based on their own measurements with the HIRES spectrograph at the Keck Observatory in Hawaii and the Automated Planet Finder at the Lick Observatory . The names of the planets used by the two astronomical teams sometimes differ from one another.

In all cases, all planets were verified using the radial velocity method . However, the innermost planet, HD 219134 b , is passing directly in front of HR 8832 as it orbits its central star from Earth . It could therefore also be detected and confirmed with the Spitzer Space Telescope using the transit method . At the time of its discovery, HD 219134 b was the closest exoplanet to the Sun that can be observed in transit. It has about 1.6 times the radius of the earth and about 4.7 times the mass of the earth . Based on the known data on radius and minimum mass, the density of the planet could be estimated at about 5.89 cm ³ , whereby HD 219134 b can be classified as a rocky planet .

The next outer planet HD 219134 c was also recognized as a transit planet in 2017. It has approximately 1.5 times the Earth's radius and a little less than 4.4 times the Earth's mass. Like HD 219134 b, it is very likely also a rocky planet.

The two following planets HD 219134 f and d are more massive and each have at least 7.3 and 16.1 times the mass of the earth. They too orbit very closely around their star. There are indications of two other planets further away. The outermost planet HD 219134 h has about 20% of the mass of the planet Jupiter in the solar system .

Planetary system from HR 8832 (HD 219134)

Planet (by distance from the star)	Discovery (year)	Mass (in M ♁ )	Radius (in ) ${\displaystyle R_{\oplus }}$	Cycle time (in days)	Major semi-axis (in AU )	eccentricity
HD 219134 b	2015	4.74 ± 0.19	1.602 ± 0.055	3.092926 ± 0.000010	0.03876 ± 0.00047	0
HD 219134 c	2015	4.36 ± 0.22	1.511 ± 0.047	6.76458 ± 0.00033	0.06530 ± 0.00080	0.0620 ± 0.0390
HD 219134 f	2015	> 7.30 ± 0.40	> 1.31 ± 0.02	22.717 ± 0.015	0.1463 ± 0.0018	0.148 ± 0.047
HD 219134 d	2015	> 16.17 ± 0.64	> 1.61 ± 0.02	46.859 ± 0.028	0.2370 ± 0.0030	0.138 ± 0.025
HD 219134 g	2015	11 ± 1	-	94.2 ± 0.2	0.3753 ± 0.0004	0
HD 219134 h	2015	108 ± 6	-	2247 ± 43	3.11 ± 0.04	0.06 ± 0.04

Web links

• SolStation.com: BD + 56 2966 / HR 8832. Retrieved August 1, 2015 .  (English)
• Stars and space from July 31, 2015: Our closest distant neighbor in space . Retrieved August 2, 2015 . 

Individual evidence

1. ↑ ^{a b c d e f} SIMBAD : HD 219134. Accessed August 1, 2015 . 
2. ↑ ^{a b} Oja, T .: UBV photometry of stars whose positions are accurately known. III . bibcode : 1986A & AS ... 65..405O .
3. ↑ ^{a b c} Takeda, Genya et al .: Structure and Evolution of Nearby Stars with Planets II. Physical Properties of ~ 1000 Cool Stars from the SPOCS Catalog . arxiv : 0904.0819 .
4. ↑ ^{a b} Perrin, M.-N .; Karoji, H .: Stellar radius determination from IRAS 12-micron fluxes . bibcode : 1987A & A ... 172..235P .
5. ↑ ^{a b} Frasca, A. et al .: REM near-IR and optical photometric monitoring of pre-main sequence stars in Orion. Rotation periods and starspot parameters . bibcode : 2009A & A ... 508.1313F .
6. ↑ ^{a b c d e} Johnson Marshall et al .: A 12-Year Activity Cycle for HD 219134 . arxiv : 1602.05200 .
7. ^ Moreno, H .: On the transfer of photometric systems . bibcode : 1971A & A .... 12..442M .
8. ↑ ^{a b} Cumming, A. et al .: The Lick Planet Search: Detectability and Mass Thresholds . arxiv : astro-ph / 9906466 .
9. ↑ ^{a b c d} Motalebi, F. et al .: The HARPS-N Rocky Planet Search I. HD219134b: A rocky planet transiting in a multi-planet system at 6.5 pc from the Sun . arxiv : 1507.08532 .
10. ↑ ^{a b c} Steven S. Vogt et al .: A Six-Planet System Orbiting HD 219134 . arxiv : 1509.07912 .
11. ↑ ^{a b} Jet Propulsion Laboratory: NASA's Spitzer Confirms Closest Rocky Exoplanet. Retrieved August 1, 2015 . 
12. ↑ Stars and Space from July 31, 2015: Our closest distant neighbor in space . Retrieved August 2, 2015 . 
13. ↑ ^{a b c d} Michael Gillon et al .: Two massive rocky planets transiting a K-dwarf 6.5 parsecs away . arxiv : 1703.01430 .
14. ↑ ^{a b c d e f} NASA Exoplanet Archive : HD 219134. Retrieved February 13, 2018 .