Rho Coronae Borealis

Rho Coronae Borealis (ρ CrB, ρ Coronae Borealis) is a yellow dwarf star approximately 57 light-years away in the constellation of Corona Borealis. The star is thought to be similar to the Sun with nearly the same mass, radius, and luminosity. It is orbited by two known exoplanets.[4]

Not to be confused with R Coronae Borealis.
ρ Coronae Borealis
Location of ρ Coronae Borealis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Corona Borealis
Right ascension 16h 01m 02.662s[1]
Declination +33° 18′ 12.63″[1]
Apparent magnitude (V) 5.4[2]
Characteristics
Spectral type G0V[3]
B−V color index 0.61
Astrometry
Radial velocity (Rv)18.4 km/s
Proper motion (μ) RA: −196.63±0.24[1] mas/yr
Dec.: −773.02±0.21[1] mas/yr
Parallax (π)58.02 ± 0.28[1] mas
Distance56.2 ± 0.3 ly
(17.24 ± 0.08 pc)
Absolute magnitude (MV)+4.21[2]
Details
Mass0.91[3] M☉
Radius1.3617±0.0262[3] R☉
Luminosity1.7059±0.0423[3] L☉
Surface gravity (log g)4.12[2] cgs
Temperature5627±54[3] K
Metallicity [Fe/H]-0.24 (± 0.08)[2] dex
Rotational velocity (v sin i)1.0[2] km/s
Age10.2[2] Gyr
Other designations
15 CrB, 2MASS J16010264+3318124, BD+33°2663, CCDM J16011+3318A, GC 21527, GJ 9537, HD 143761, HIP 78459, HR 5968, LTT 14764, ρ CrB, SAO 65024
Database references
SIMBADdata

Stellar properties

Rho Coronae Borealis is a yellow main sequence star of the spectral type G0V. The star is thought to have only 91 percent of the Sun's mass, along with 1.4 times its radius and 1.7 times its luminosity. It may only be 51 to 65 percent as enriched with elements heavier than hydrogen (based on its abundance of iron) and may be somewhat older than the Sun at around ten billion years old.

Planetary system
The Rho Coronae Borealis planetary system[4]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ≥332.1+7.5
−7.6 M⊕		 0.2196+0.0024
−0.0025		 39.8458+0.0015
−0.0014		 0.0373+0.0040
−0.0039		 — —
c ≥25±2 M⊕ 0.4123+0.0046
−0.0047		 102.54±0.17 0.052+0.061
−0.037		 — —

An extrasolar planet in a 39.8-day orbit around Rho Coronae Borealis was discovered in 1997 by observing the star's radial velocity variations.[5] This detection method only gives a lower limit on the true mass of the companion. In 2001, preliminary Hipparcos astrometric satellite data indicated that the orbital inclination of the star's companion was 0.5°, nearly face-on, implying that its mass was as much as 115 times Jupiter's.[6] A paper published in 2011 supported this claim using a new reduction of the astrometric data, with an updated mass value of 169.7 times Jupiter, with a 3σ confidence region 100.1 to 199.6 Jupiter masses.[7] Such a massive body would be a dim red dwarf star, not a planet. In 2016, however, a paper was published that used interferometry to rule out any stellar companions to this star, in addition to detecting a second planetary companion in a 102-day orbit.[4]

Searches for circumstellar material

In October 1999, astronomers at the University of Arizona announced the existence of a circumstellar disk around the star.[8] Follow-up observations with the Spitzer Space Telescope failed to confirm this detect any infrared excess at 24- or 70-micrometre wavelengths, which would be expected if a disk were present.[9][10][11] No evidence for a disc was detected in observations with the Herschel Space Observatory either.[12]

See also

References
  1. van Leeuwen, F. (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. Vizier catalog entry
  2. Fuhrmann, Klaus; Pfeiffer, Michael J.; Bernkopf, Jan (1998). "F- and G-type stars with planetary companions: Upsilon Andromedae, rho (1) Cancri, tau Bootis, 16 Cygni and rho Coronae Borealis". Astronomy and Astrophysics. 336: 942. Bibcode:1998A&A...336..942F.
  3. 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. Fulton, Benjamin J.; et al. (October 2016). "Three Temperate Neptunes Orbiting Nearby Stars". The Astrophysical Journal. 830 (1): 46. arXiv:1607.00007. Bibcode:2016ApJ...830...46F. doi:10.3847/0004-637X/830/1/46.
  5. Noyes, Robert W.; et al. (1997). "A Planet Orbiting the Star ρ Coronae Borealis". Astrophysical Journal. 483 (2): L111–L114. arXiv:astro-ph/9704248. Bibcode:1997ApJ...483L.111N. doi:10.1086/310754.
  6. Han, Inwoo; Black, David C.; Gatewood, George (2001). "Preliminary Astrometric Masses for Proposed Extrasolar Planetary Companions". The Astrophysical Journal. 548 (1): L57–L60. Bibcode:2001ApJ...548L..57H. doi:10.1086/318927.
  7. Reffert, S.; Quirrenbach, A. (2011). "Mass constraints on substellar companion candidates from the re-reduced Hipparcos intermediate astrometric data: nine confirmed planets and two confirmed brown dwarfs". Astronomy & Astrophysics. 527. id.A140. arXiv:1101.2227. Bibcode:2011A&A...527A.140R. doi:10.1051/0004-6361/201015861.
  8. Trilling, D. E.; Brown, R. H.; Rivkin, A. S. (2000). "Circumstellar Dust Disks around Stars with Known Planetary Companions". The Astrophysical Journal. 529 (1): 499–505. Bibcode:2000ApJ...529..499T. doi:10.1086/308280.
  9. Beichman, C. A.; Bryden, G.; Rieke, G. H.; Stansberry, J. A.; Trilling, D. E.; Stapelfeldt, K. R.; Werner, M. W.; Engelbracht, C. W.; et al. (2005). "Planets and Infrared Excesses: Preliminary Results from a Spitzer MIPS Survey of Solar-Type Stars". The Astrophysical Journal. 622 (2): 1160–1170. arXiv:astro-ph/0412265. Bibcode:2005ApJ...622.1160B. doi:10.1086/428115.
  10. Bryden, G.; Beichman, C. A.; Carpenter, J. M.; Rieke, G. H.; Stapelfeldt, K. R.; Werner, M. W.; Tanner, A. M.; Lawler, S. M.; et al. (2009). "Planets and Debris Disks: Results from a Spitzer/MIPS Search for Infrared Excess" (PDF). The Astrophysical Journal. 705 (2): 1226–1236. Bibcode:2009ApJ...705.1226B. doi:10.1088/0004-637X/705/2/1226.
  11. Caer McCabe & Carlotta Pham. "Catalog of withdrawn or refuted resolved Disks". Catalog of Resolved Circumstellar Disks. Archived from the original on 2009-01-05. Retrieved 2010-04-03.
  12. Marshall, J. P.; Moro-Martín, A.; Eiroa, C.; Kennedy, G.; Mora, A.; Sibthorpe, B.; Lestrade, J.-F.; Maldonado, J.; et al. (2014). "Correlations between the stellar, planetary, and debris components of exoplanet systems observed by Herschel". Astronomy & Astrophysics. 565. id.A15. arXiv:1403.6186. Bibcode:2014A&A...565A..15M. doi:10.1051/0004-6361/201323058.

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