HD 69830

HD 69830

HD 69830 is a G8V class star less massive than the Sun (G2V)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Puppis
Right ascension 08h 18m 23.94706s[1]
Declination −12° 37′ 55.8116″[1]
Apparent magnitude (V) +5.98[2]
Characteristics
Spectral type G8V[3]
U−B color index 0.33[2]
B−V color index 0.75[2]
V−R color index 0.40
R−I color index 0.36
Variable type none
Astrometry
Radial velocity (Rv)+30.4[4] km/s
Proper motion (μ) RA: 278.99 ± 0.25[1] mas/yr
Dec.: −987.59 ± 0.29[1] mas/yr
Parallax (π)80.04 ± 0.35[1] mas
Distance40.7 ± 0.2 ly
(12.49 ± 0.05 pc)
Absolute magnitude (MV)5.47 ± 0.01[5]
Details
Mass0.863 ± 0.043[6] M☉
Radius0.905 ± 0.019[6] R☉
Luminosity0.622 ± 0.014[6] L☉
Surface gravity (log g)4.53[7] cgs
Temperature5,394 ± 62[3] K
Metallicity [Fe/H]−0.04 ± 0.03[3] dex
Rotation35.1 ± 0.8 days[8]
Rotational velocity (v sin i)0.8±0.5[3] km/s
Age10.6 ± 4[3] Gyr
Other designations
285 G. Puppis,[9] BD−12°2449, GJ 302, HIP 40693, HR 3259, LHS 245, SAO 154093[10]
Database references
SIMBADdata
Exoplanet Archivedata
ARICNSdata
Extrasolar Planets
Encyclopaedia		data

HD 69830 (285 G. Puppis) is an yellow dwarf star approximately 41 light-years away in the constellation of Puppis. In 2005, the Spitzer Space Telescope discovered a debris disk orbiting the star.[11] The disk contains substantially more dust than the Solar System's asteroid belt. As of 2006, it has been confirmed that three extrasolar planets with minimum masses comparable to Neptune orbit the star, located interior to the debris disk.[12]

Distance and visibility

HD 69830 is a G-type main sequence star of the spectral type G8V. The star has a mass of about 86 percent the Sun, 90 percent of its radius, 62 percent of its luminosity, and 11 percent less iron abundance. Its age is about 10.6 ± 4 billion years. HD 69830 is located about 40.7 light-years from the Sun, lying in the northeastern part of the constellation of Puppis (the Poop Deck). The star can be found east of Sirius, southwest of Procyon, northeast of Delta Canis Majoris, and north of Zeta Puppis.

Planetary system

The HD 69830 planetary system[12][13]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b 10.2 M⊕ 0.0785 8.667 ± 0.003 0.1 ± 0.04 — —
c 11.8 M⊕ 0.186 31.56 ± 0.04 0.13 ± 0.06 — —
d 18.1 M⊕ 0.63 197 ± 3 0.07 ± 0.07 — ~4 R⊕
Asteroid belt 0.93–1.16 AU — —

Planets

On May 17, 2006, a team of astronomers using the European Southern Observatory's (ESO) HARPS spectrograph on the 3.6-metre La Silla telescope in the Atacama desert, Chile, announced the discovery of three extrasolar planets orbiting the star. With minimum masses between 10 and 18 times that of the Earth, all three planets are presumed to be similar to the planets Neptune or Uranus. As of 2011, no planet with more than half the mass of Jupiter had been detected within three astronomical units of HD 69830.

The star rotates at an inclination of 13+27
−13 degrees relative to Earth.[8] It has been assumed that the planets share that inclination.[14] However b and c are "hot Neptunes", and outside this system several are now known to be oblique relative to the stellar axis.[15]

The outermost planet discovered appears to be within the system's habitable zone, where liquid water would remain stable (more accurate data on the primary star's luminosity will be required to know for sure where the habitable zone is). HD 69830 is the first extrasolar planetary system around a Sun-like star without any known planets comparable to Jupiter or Saturn in mass.

Debris disk

In 2005, the Spitzer Space Telescope detected a debris disk in the HD 69830 system consistent with being produced by an asteroid belt twenty times more massive than that in our own system. The belt was originally thought to be located inside an orbit equivalent to that of Venus in the Solar System, which would place it between the orbits of the second and third planets. The disk contains sufficient quantities of dust that the nights on any nearby planets would be lit up by zodiacal light 1000 times brighter than that seen on Earth, easily outshining the Milky Way.

Further analysis of the spectrum of the dust revealed that it is composed of highly processed material, likely derived from a disrupted C-type asteroid of at least 30 km radius which contained many small olivine-rich (rocky) and once-wet grains which would not survive at close distances to the star. Instead, it seems more likely that the asteroid belt producing the dust is located outside the orbit of the outermost planet, around 1 AU from the star. This region contains the 2:1 and 5:2 mean motion resonances with HD 69830 d.[13]

Artist's impression from 2005 of the asteroid belt and a hypothetical outer planet.
 
A comparison between the night sky of Earth and a planet of HD 69830.
 
The orbits of the planets of HD 69830 and the debris disk.
 

See also

Wikimedia Commons has media related to HD 69830.

References

  1. 1 2 3 4 5 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.Vizier catalog entry
  2. 1 2 3 Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV data. SIMBAD, Bibcode:1986EgUBV........0M.
  3. 1 2 3 4 5 STELLAR PARAMETERS FOR HD 69830, A NEARBY STAR WITH THREE NEPTUNE MASS PLANETS AND AN ASTEROID BELT. Angelle Tanner, Tabetha S. Boyajian, Kaspar von Braun, Stephen Kane, John M. Brewer, Chris Farrington, Gerard T. van Belle, Charles A. Beichman, Debra Fischer, Theo A. ten Brummelaar, Harold A. McAlister, Gail Schaefer. 17 December 2014. Retrieved 17 July 2016.
  4. ↑ Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick, eds., "Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30", Determination of Radial Velocities and their Applications, University of Toronto: International Astronomical Union, 30: 57, Bibcode:1967IAUS...30...57E. |contribution= ignored (help)
  5. ↑ Holmberg, J.; et al. (2009). "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics". Astronomy and Astrophysics. 501 (3): 941–947. arXiv:0811.3982Freely accessible. Bibcode:2009A&A...501..941H. doi:10.1051/0004-6361/200811191.Vizier catalog entry
  6. 1 2 3 Tanner, Angelle; et al. (February 2015), "Stellar Parameters for HD 69830, a Nearby Star with Three Neptune Mass Planets and an Asteroid Belt", The Astrophysical Journal, 800 (2): 5, arXiv:1412.5251Freely accessible, Bibcode:2015ApJ...800..115T, doi:10.1088/0004-637X/800/2/115, 115.
  7. ↑ Ramírez, I.; et al. (February 2013), "Oxygen abundances in nearby FGK stars and the galactic chemical evolution of the local disk and halo", The Astrophysical Journal, 764 (1): 78, arXiv:1301.1582Freely accessible, Bibcode:2013ApJ...764...78R, doi:10.1088/0004-637X/764/1/78.
  8. 1 2 Simpson, E. K.; et al. (November 2010), "Rotation periods of exoplanet host stars", Monthly Notices of the Royal Astronomical Society, 408 (3): 1666–1679, arXiv:1006.4121Freely accessible, Bibcode:2010MNRAS.408.1666S, doi:10.1111/j.1365-2966.2010.17230.x.
  9. ↑ Benjamin Apthorp Gould, reprinted; updated by Frederick Pilcher. "Uranometria Argentina". Retrieved 2011-02-04.
  10. ↑ "HD 69830 -- High proper-motion Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2015-04-25.
  11. ↑ Beichman, C. A.; et al. (2005). "An Excess Due to Small Grains around the Nearby K0 V Star HD 69830: Asteroid or Cometary Debris?". The Astrophysical Journal. 626 (2): 1061–1069. arXiv:astro-ph/0504491Freely accessible. Bibcode:2005ApJ...626.1061B. doi:10.1086/430059.
  12. 1 2 Lovis, Christophe; et al. (2006). "An extrasolar planetary system with three Neptune-mass planets" (PDF). Nature. 441 (7091): 305–309. arXiv:astro-ph/0703024Freely accessible. Bibcode:2006Natur.441..305L. doi:10.1038/nature04828. PMID 16710412.
  13. 1 2 Lisse, C. M.; et al. (2007). "On the Nature of the Dust in the Debris Disk Around HD 69830". The Astrophysical Journal. 658 (1): 584–592. arXiv:astro-ph/0611452Freely accessible. Bibcode:2007ApJ...658..584L. doi:10.1086/511001.
  14. ↑ "hd_69830_b". Extrasolar Planet Encyclopaedia. Retrieved November 12, 2012.
  15. ↑ Roberto Sanchis-Ojeda; Josh N. Winn; Daniel C. Fabrycky (2012). "Starspots and spin-orbit alignment for Kepler cool host stars". Astronomische Nachrichten. 334: 180. arXiv:1211.2002Freely accessible. Bibcode:2013AN....334..180S. doi:10.1002/asna.201211765.

Coordinates: 08h 18m 23.9s, −12° 37′ 55.0″

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