Astronomy:HD 92945

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Short description: K-type star in the constellation Hydra
HD 92945
250px
A light curve for V419 Hydrae, plotted over one 13.47 day period, from TESS data[1]
Observation data
Equinox J2000.0]] (ICRS)
Constellation Hydra[2]
Right ascension  10h 43m 28.2716s[3]
Declination −29° 03′ 51.433″[3]
Apparent magnitude (V) 7.72[4]
Characteristics
Evolutionary stage main sequence[3]
Spectral type K1V[5]
U−B color index +0.55[6]
B−V color index +0.88[6]
Variable type BY Dra[4]
Astrometry
Radial velocity (Rv)22.706±0.14[3] km/s
Proper motion (μ) RA: −215.484[3] mas/yr
Dec.: −49.892[3] mas/yr
Parallax (π)46.4931 ± 0.0198[3] mas
Distance70.15 ± 0.03 ly
(21.509 ± 0.009 pc)
Absolute magnitude (MV)6.07[2]
Details
Mass0.86±0.01[7] M☉
Radius0.77[8] R☉
Luminosity0.38[8] L☉
Surface gravity (log g)4.39[9] cgs
Temperature5000[10] K
Metallicity [Fe/H]−0.17[10] dex
Rotation6.2 days[9]
Rotational velocity (v sin i)4[10] km/s
Age294±23[8] Myr
Other designations
V419 Hydrae, V419 Hya, CD−28 8394, CPD−28 4175, GJ 3615, HIP 52462, LTT 3932, NLTT 25167, PPM 258065, SAO 179168, 2MASS J10432828-2903513[11]
Database references
SIMBADdata

HD 92945 is a K-type main sequence star located 70 light years away in the northern constellation of Hydra. Its apparent visual magnitude varies by 0.02 magnitudes and is approximately 7.72 at maximum brightness.[4]

Debris disk

Image of the debris disk with the REASONS survey[12]
Image of the debris disk with the REASONS survey[12]

In 2007, a debris disk with estimated dust mass 0.047±0.003 M🜨[13] has been observed around the star by coronagraphic imaging, using the ACS and NICMOS instruments on the Hubble Space Telescope. It appears to extend 45 to 175 astronomical units from HD 92945.[14]

The disk has a gap 20+10
−8 astronomical unit|AU wide at a radius of 73±3 astronomical unit|AU, which may be being carved by a planet.[13] No planet with mass exceeding 1-2 MJ was observed in the gap,[15] but a lower-mass planet or a chain of two planets are still possible.[7]

Evidence for a planet via astrometric observations was presented in 2024.[16] It could be explain the presence of the gap through long-term resonances with the disk, as its orbital separation is much less than the gap's radius and thus the planet would not be carving the disk directly. Alternatively, both the inner planet and an additional planet within the gap could be shepherding the disk through long-term gravitational interactions.[7]

The HD 92945 planetary system
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(years) 		Eccentricity Inclination Radius
Debris disk 50[13]–140[13] AU 65.4±0.9[13]° —
(unconfirmed) 0.4 – 5[7] MJ 2.5 – 30[7] — — — —

References

  1. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html. 
  2. ↑ 2.0 2.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A  XHIP record for this object at VizieR.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 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.
  4. ↑ 4.0 4.1 4.2 V419 Hya, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars , Sternberg Astronomical Institute, Moscow, Russia. Accessed on line February 2, 2011.
  5. ↑ Torres, C. A. O.; Quast, G. R.; Da Silva, L.; de la Reza, R.; Melo, C. H. F.; Sterzik, M. (2006). "Search for associations containing young stars (SACY). I. Sample and searching method". Astronomy and Astrophysics 460 (3): 695. doi:10.1051/0004-6361:20065602. Bibcode: 2006A&A...460..695T. 
  6. ↑ 6.0 6.1 Koen, C.; Kilkenny, D.; Van Wyk, F.; Marang, F. (2010). "UBV(RI)C JHK observations of Hipparcos-selected nearby stars". Monthly Notices of the Royal Astronomical Society 403 (4): 1949. doi:10.1111/j.1365-2966.2009.16182.x. Bibcode: 2010MNRAS.403.1949K. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 Bendahan-West, R; Marino, S; Carter, A L; Squicciarini, V; James, A D; Sefilian, A A; Pearce, T D; Friebe, M F et al. (2025-12-22). "JWST /MIRI coronagraphic search for planets in systems with gapped exoKuiper belts and proper motion anomalies" (in en). Monthly Notices of the Royal Astronomical Society. doi:10.1093/mnras/staf2255. ISSN 0035-8711. 
  8. ↑ 8.0 8.1 8.2 Plavchan, Peter et al. (June 2009). "New Debris Disks Around Young, Low-Mass Stars Discovered with the Spitzer Space Telescope". The Astrophysical Journal 698 (2): 1068–1094. doi:10.1088/0004-637X/698/2/1068. Bibcode: 2009ApJ...698.1068P. 
  9. ↑ 9.0 9.1 Hojjatpanah, S.; Oshagh, M.; Figueira, P.; Santos, N. C.; Amazo-Gómez, E. M.; Sousa, S. G.; Adibekyan, V.; Akinsanmi, B. et al. (2020). "The correlation between photometric variability and radial velocity jitter. Based on TESS and HARPS observations". Astronomy and Astrophysics 639. doi:10.1051/0004-6361/202038035. Bibcode: 2020A&A...639A..35H. 
  10. ↑ 10.0 10.1 10.2 HD 92945, database entry, The Geneva-Copenhagen Survey of Solar neighbourhood, J. Holmberg et al., 2007, CDS ID V/117A. Accessed on line February 2, 2011.
  11. ↑ "V* V419 Hya". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V%2A+V419+Hya. 
  12. ↑ Matrà, L.; Marino, S.; Wilner, D. J.; Kennedy, G. M.; Booth, M.; Krivov, A. V.; Williams, J. P.; Hughes, A. M. et al. (2025-01-15). "REsolved ALMA and SMA Observations of Nearby Stars (REASONS): A population of 74 resolved planetesimal belts at millimetre wavelengths". Astronomy and Astrophysics 693. doi:10.1051/0004-6361/202451397. Bibcode: 2025A&A...693A.151M. 
  13. ↑ 13.0 13.1 13.2 13.3 13.4 Marino, S.; Yelverton, B.; Booth, M.; Faramaz, V.; Kennedy, G. M.; Matrà, L.; Wyatt, M. C. (2019). "A gap in HD 92945's broad planetesimal disc revealed by ALMA". Monthly Notices of the Royal Astronomical Society 484: 1257–1269. doi:10.1093/mnras/stz049. 
  14. ↑ Golimowski, D.; John Krist, J.; Chen, C.; Stapelfeldt, K.; Ardila, D.; Clampin, M.; Schneider, G.; Silverstone, M. et al. (2007). "Observations and Models of the Debris Disk around the K dwarf HD 92945". In the Spirit of Bernard Lyot: The Direct Detection of Planets and Circumstellar Disks in the 21st Century: 46. Bibcode: 2007lyot.confE..46G. 
  15. ↑ Mesa, D. et al. (2021). "Limits on the presence of planets in systems with debris discs: HD 92945 and HD 107146". Monthly Notices of the Royal Astronomical Society 503: 1276–1289. doi:10.1093/mnras/stab438. 
  16. ↑ Gratton, R.; Bonavita, M.; Mesa, D.; Desidera, S.; Zurlo, A.; Marino, S.; D’Orazi, V.; Rigliaco, E. et al. (2024-05-01). "Stellar companions and Jupiter-like planets in young associations" (in en). Astronomy & Astrophysics 685: A119. doi:10.1051/0004-6361/202348393. ISSN 0004-6361. 



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