Astronomy:Eta Corvi

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Short description: Star in the constellation of Corvus
Eta Corvi
Location of η Corvi (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Corvus
Right ascension  12h 32m 04.22640s[1]
Declination −16° 11′ 45.6186″[1]
Apparent magnitude (V) 4.29–4.32[2]
Characteristics
Evolutionary stage main sequence[3]
Spectral type F2 V[4]
U−B color index +0.00[5]
B−V color index +0.38[5]
R−I color index +0.18[6]
Variable type Suspected[2]
Astrometry
Radial velocity (Rv)−1.164±0.135[1] km/s
Proper motion (μ) RA: −424.597±0.168[1] mas/yr
Dec.: −58.241±0.157[1] mas/yr
Parallax (π)54.8135 ± 0.1562[1] mas
Distance59.5 ± 0.2 ly
(18.24 ± 0.05 pc)
Absolute magnitude (MV)2.99[7]
Details
Mass1.41±0.05[8] M☉
Radius1.61±0.03[8] R☉
Luminosity5.05+0.25
−0.26[8] L☉
Surface gravity (log g)4.24[8] cgs
Temperature6,823+60
−55[8] K
Metallicity [Fe/H]−0.06±0.04[9] dex
Rotational velocity (v sin i)68±2[10] km/s
Age1.57+0.46
−0.36[8] Gyr
Other designations
η Crv, 8 Crv, NSV 5690, BD−15°3489, GC 17087, GJ 471.2, HD 109085, HIP 61174, HR 4775, SAO 157345, PPM 225971, LTT 4755, NLTT 31021[11]
Database references
SIMBADdata
ARICNSdata

Eta Corvi is an F-type main-sequence star, the sixth-brightest star in the constellation of Corvus. It is located 59.5 light-years (18.2 parsecs) from the Sun based on its parallax. The star is faintly visible to the naked eye, at an apparent magnitude of +4.3. Two debris disks have been detected orbiting this star: a cold outer disk at ~150 AU, and a warm/hot inner disk within a few astronomical units (AU). The inner disk is notable for being brighter than expected, suggesting that it is replenished by materials from the outer disk.

Nomenclature

η Corvi (Latinised to Eta Corvi) is the star's Bayer designation, abbreviated Eta Crv or η Crv. It is also often referred by its Henry Draper Catalogue designation HD 109085.[11]

In Chinese astronomy, Eta Corvi is called 左轄, Pinyin: Zuǒxiá, meaning Left Linchpin, because this star is marking itself and stands alone in the Left Linchpin asterism, Chariot mansion (see: Chinese constellation).[12] This was transliterated as Tso Hea by R. H. Allen, but was listed as a name for β Corvi (Kraz).[13]

Properties

A yellow-white main sequence star of spectral type F2V, Eta Corvi has an estimated surface temperature of 6823 K. It is about 1.4 times as massive as the Sun and 5 times as luminous.[8] The concentration of iron and other heavy elements in its atmosphere is approximately 90% that of the Sun's.[9] The projected rotational velocity at the star's equator (v sin i) is 68 km/s - more than 30 times faster than that for the Sun.[10] It is about 30% of the Sun's age.[8]

Planetary system

The Eta Corvi planetary system[14][15]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(years) 		Eccentricity Inclination Radius
Inner disk 6.4±2.7 AU — —
Outer disk 127–180 AU 39+1
−1° 		—

Debris disks

Image of the debris disk with the REASONS survey[15]
Image of the debris disk with the REASONS survey[15]

Eta Corvi possesses two dust disks. The cold outer disk is located at 150 au, is 50 au wide, and is inclined at 40° from face-on orientation.[15] The warm inner disk is located within a few au of the star.[14] The temperature of the cold dust is around 40 K, while the temperature of the warm dust is 300–400 K.[14][16]

Excess dust surrounding Eta Corvi was first identified by the IRAS satellite through detection of an excess of infrared radiation from the star.[17] Spectral energy distribution data suggested the presence of dust populations with different temperatures.[18][16] The dust was first directly imaged in 2005, revealing a ring of cold dust with a radius of about 150 au, and a relatively empty inner cavity within 100 au possibly cleared by a planetary system,[16] a result supported by subsequent submillimetre observation attempts.[19][14] The warm dust component was found to likely reside within a few au of the star.[20][14]

The dust within the outer disk cannot be primordial, as collisions between dust grains would break them into sufficiently small grains that can then be removed by radiation pressure. This suggests the dust is constantly replenished by collisional cascade, where collisions between planetesimals break large bodies into objects of various sizes, including dust. The inferred initial total planetesimal mass is around 20 Earth masses.[16]

Artist's conception of a storm of comets in the Eta Corvi system, with a possible planet

The warm dust disk component around Eta Corvi is notable for being more luminous than the maximum theoretical luminosity of the disk, derived from collisions between planetesimals formed within the disk itself.[21] Additionally, the composition of the warm dust appears to resemble cometary materials, with primitive silicates not processed by aqueous alteration, as well as carbon-bearing species and water. Evidence of silica dust has also been detected, indicating high velocity collisions on the order of 5–10 km/s.[22] These may hence be explained by an influx of planetesimals from a reservoir in the outer system migrating into the inner system before being destroyed by collisions, producing the observed dust.[21] The warm dust emission appears to remain stable over 30 years, suggesting that the inner disk is efficiently replenished.[14] The transport of outer disk planetesimals to the inner system may involve a steady state configuration of planets scattering materials inwards, or a one-off event analogous to the Late Heavy Bombardment (LHB) involving instability between planets.[22][14] Observations of the outer disk favors the steady state model, as an LHB-like instability would have resulted in a broader outer disk.[23]

The debris disks of Eta Corvi has been imaged by the James Webb Space Telescope (JWST) on 20 May 2025.[24] The results have been presented at the 247th Meeting of the American Astronomical Society, the 25.5 micrometre imaging revealing a much more compact disk than the outer disk, possibly suggesting a quiet collisional history in the outer disk itself.[25] As of March 2026, these results have not yet been published.

Planets

Currently, no planet around Eta Corvi has been detected. Radial velocity measurements have ruled out companions with masses down to 6 Jupiter masses orbiting within 2000 days (~3 au).[26][27][23]

Several papers have made predictions of planets based on the distribution of dust disks in the system. The transportation of planetesimals into the inner system may require one or more perturbing planets, and there may also be an inner planet struck by the planetesimals to produce the observed warm dust. Lisse et al. (2012) predicted a migrating giant planet orbiting at 100–150 au, and a rocky planet less massive than Earth based on impact velocity and escape velocity constraints.[22] Marino et al. (2016) proposed either a low-mass planet embedded within the outer disk, a single perturber orbiting near the disk's inner edge, or a chain of planets with masses between 3–30 Earth masses, and in the case that the warm dust is produced by impacts on a planet, the paper predicted a 4–10 Earth masses planet based on production of sufficient debris to remain detectable over long time.[23] Pearce et al. (2022) predicted a single planet sculpting the debris disk with a mass of ≥0.34 Jupiter masses at 104 au.[28]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 Kukarin, B.W.. "NSV 5690". Institute of Astronomy of Russian Academy of Sciences/Sternberg Astronomical Institute. http://www.sai.msu.su/groups/cluster/gcvs/gcvs/nsv/nsv.dat. 
  3. ↑ Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics 537: A120. doi:10.1051/0004-6361/201117691. Bibcode: 2012A&A...537A.120Z. 
  4. ↑ Gray, R. O.; Corbally, C. J.; Garrison, R. F. et al. (2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc--The Southern Sample". The Astronomical Journal 132 (1): 161–170. doi:10.1086/504637. ISSN 0004-6256. Bibcode: 2006AJ....132..161G. 
  5. ↑ 5.0 5.1 Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode: 1986EgUBV........0M. 
  6. ↑ Hoffleit, D.; Warren, W. H. Jr.. "HR 4775". Bright Star Catalogue. Centre de données astronomiques de Strasbourg. http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=V/50/catalog&recno=4775. 
  7. ↑ Holmberg, J. (2007). "HD 109085". The Geneva-Copenhagen Survey of Solar Neighbourhood. Centre de données astronomiques de Strasbourg. http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=V/117A/newcat.dat&recno=8509.  See also Nordström, B. (2004). "The Geneva-Copenhagen survey of the Solar neighbourhood: Ages, metallicities and kinematic properties of ~14,000 F and G dwarfs". Astronomy & Astrophysics 418 (3): 989–1019. doi:10.1051/0004-6361:20035959. Bibcode: 2004A&A...418..989N. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 Harada, Caleb K. et al. (June 2024). "Setting the Stage for the Search for Life with the Habitable Worlds Observatory: Properties of 164 Promising Planet-survey Targets". The Astrophysical Journal Supplement Series 272 (2): id. 30. doi:10.3847/1538-4365/ad3e81. Bibcode: 2024ApJS..272...30H. 
  9. ↑ 9.0 9.1 Gáspár, András; Rieke, George H.; Ballering, Nicholas (2016-08-01). "The Correlation between Metallicity and Debris Disk Mass". The Astrophysical Journal 826 (2): 171. doi:10.3847/0004-637X/826/2/171. ISSN 0004-637X. Bibcode: 2016ApJ...826..171G. 
  10. ↑ 10.0 10.1 Mora, A. (2001). "EXPORT: Spectral classification and projected rotational velocities of Vega-type and pre-main sequence stars". Astronomy & Astrophysics 378 (1): 116–131. doi:10.1051/0004-6361:20011098. Bibcode: 2001A&A...378..116M. 
  11. ↑ 11.0 11.1 "SIMBAD query result: eta Crv -- High Proper Motion Star". Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=HD+109085. 
  12. ↑ "Error: no |title= specified when using {{Cite web}}" (in zh). http://aeea.nmns.edu.tw/2006/0607/ap060722.html. 
  13. ↑ Allen, R. H. (1963). "Corvus". Star Names: Their Lore and Meaning. Dover Publications. https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Corvus*.html. 
  14. ↑ 14.0 14.1 14.2 14.3 14.4 14.5 14.6 Duchêne, G.; Arriaga, P.; Wyatt, M. et al. (2014-03-18). "Spatially Resolved Imaging of the Two-component η Crv Debris Disk with Herschel". The Astrophysical Journal 784 (2): 148. doi:10.1088/0004-637X/784/2/148. ISSN 0004-637X. Bibcode: 2014ApJ...784..148D. 
  15. ↑ 15.0 15.1 15.2 Matrà, L.; Marino, S.; Wilner, D. J. et al. (2025). "REsolved ALMA and SMA Observations of Nearby Stars (REASONS)". Astronomy & Astrophysics (EDP Sciences) 693: A151. doi:10.1051/0004-6361/202451397. ISSN 0004-6361. Bibcode: 2025A&A...693A.151M. 
  16. ↑ 16.0 16.1 16.2 16.3 Wyatt, M. C.; Greaves, J. S.; Dent, W. R. F.; Coulson, I. M. (2005-02-10). "Submillimeter Images of a Dusty Kuiper Belt around η Corvi". The Astrophysical Journal 620 (1): 492–500. doi:10.1086/426929. ISSN 0004-637X. Bibcode: 2005ApJ...620..492W. 
  17. ↑ Stencel, R. E.; Backman, D. E. (1991). "A survey for infrared excesses among high galactic latitude SAO stars". The Astrophysical Journal Supplement Series 75: 905–924. doi:10.1086/191553. Bibcode: 1991ApJS...75..905S. 
  18. ↑ Sheret, I.; Dent, W. R. F.; Wyatt, M. C. (2004). "Submillimetre observations and modelling of Vega-type stars". Monthly Notices of the Royal Astronomical Society 348 (4): 1282–1294. doi:10.1111/j.1365-2966.2004.07448.x. Bibcode: 2004MNRAS.348.1282S. 
  19. ↑ Matthews, B. C.; Sibthorpe, B.; Kennedy, G. et al. (2010). "Resolving debris discs in the far-infrared: Early highlights from the DEBRIS survey". Astronomy and Astrophysics (EDP Sciences) 518: L135. doi:10.1051/0004-6361/201014667. ISSN 0004-6361. Bibcode: 2010A&A...518L.135M. 
  20. ↑ Smith, R.; Wyatt, M. C.; Dent, W. R. F. (2008-04-28). "The nature of mid-infrared excesses from hot dust around Sun-like stars". Astronomy & Astrophysics (EDP Sciences) 485 (3): 897–915. doi:10.1051/0004-6361:20078719. ISSN 0004-6361. Bibcode: 2008A&A...485..897S. 
  21. ↑ 21.0 21.1 Wyatt, M. C. (2007). "Transience of Hot Dust around Sun-like Stars". The Astrophysical Journal 658 (1): 569–583. doi:10.1086/510999. Bibcode: 2007ApJ...658..569W. 
  22. ↑ 22.0 22.1 22.2 Lisse, C. M (2012). "Spitzer Evidence for a Late Heavy Bombardment and the Formation of Urelites in η Corvi at ~1 Gyr". The Astrophysical Journal 747 (2): 93. doi:10.1088/0004-637X/747/2/93. Bibcode: 2012ApJ...747...93L. 
  23. ↑ 23.0 23.1 23.2 Marino, S.; Wyatt, M. C.; Panić, O. et al. (2016-11-05). "ALMA observations of the η Corvi debris disc: inward scattering of CO-rich exocomets by a chain of 3–30 M⊕planets?". Monthly Notices of the Royal Astronomical Society (Oxford University Press (OUP)) 465 (3): 2595–2615. doi:10.1093/mnras/stw2867. ISSN 0035-8711. Bibcode: 2017MNRAS.465.2595M. 
  24. ↑ "Exo-Asteroid Belts with JWST: Pinpointing the Warm Dust Emission". STScI. https://www.stsci.edu/jwst/science-execution/program-information?id=4538. 
  25. ↑ "Exploring dust transport in asteroid belt analogs with JWST/MIRI imaging". American Astronomical Society. https://submissions.mirasmart.com/AAS247/Itinerary/PresentationDetail.aspx?evdid=2210. 
  26. ↑ Lagrange, A.-M.; Desort, M.; Galland, F.; Udry, S.; Mayor, M. (2009-01-14). "Extrasolar planets and brown dwarfs around A-F type stars. VI. High precision RV survey of early type dwarfs with HARPS". Astronomy & Astrophysics (EDP Sciences) 495 (1): 335–352. doi:10.1051/0004-6361:200810105. ISSN 0004-6361. Bibcode: 2009A&A...495..335L. 
  27. ↑ Borgniet, S.; Lagrange, A.-M.; Meunier, N.; Galland, F. (2017). "Extrasolar planets and brown dwarfs around AF-type stars. IX. The HARPS southern sample". Astronomy & Astrophysics (EDP Sciences) 599: A57. doi:10.1051/0004-6361/201628805. ISSN 0004-6361. Bibcode: 2017A&A...599A..57B. 
  28. ↑ Pearce, Tim D.; Launhardt, Ralf; Ostermann, Robert et al. (2022). "Planet populations inferred from debris discs. Insights from 178 debris systems in the ISPY, LEECH, and LIStEN planet-hunting surveys". Astronomy & Astrophysics (EDP Sciences) 659: A135. doi:10.1051/0004-6361/202142720. ISSN 0004-6361. Bibcode: 2022A&A...659A.135P. 



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