Astronomy:HD 48265

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Short description: Star in the constellation Puppis
HD 48265 / Nosaxa
Observation data
Equinox J2000.0]] (ICRS)
Constellation Puppis
Right ascension  06h 40m 01.72703s[1]
Declination −48° 32′ 31.0433″[1]
Apparent magnitude (V) 8.07[2]
Characteristics
Evolutionary stage subgiant[1]
Spectral type G5IV/V[3]
Apparent magnitude (B) ~8.80[2]
Apparent magnitude (J) 6.842±0.021[4]
Apparent magnitude (H) 6.529±0.061[4]
Apparent magnitude (K) 6.449±0.020[4]
Astrometry
Radial velocity (Rv)+23.51±0.13[1] km/s
Proper motion (μ) RA: +26.513[1] mas/yr
Dec.: +29.760[1] mas/yr
Parallax (π)11.0065 ± 0.0162[1] mas
Distance296.3 ± 0.4 ly
(90.9 ± 0.1 pc)
Absolute magnitude (MV)3.34[5]
Details
Mass1.312±0.064[6] M☉
Radius1.901±0.126[6] R☉
Luminosity3.84±0.19[7] L☉
Surface gravity (log g)3.970±0.048[6] cgs
Temperature5,733±55[6] K
Metallicity [Fe/H]+0.30±0.04[6] dex
Rotation~45 days[6]
Rotational velocity (v sin i)3.1±0.3[7] km/s
Age4.201±0.625[6] Gyr
Other designations
Nosaxa, CD−48 2430, HD 48265, HIP 31895, SAO 218115[8]
Database references
SIMBADdata
Exoplanet Archive48265 data
Extrasolar Planets
Encyclopaedia		data

HD 48265, also named Nosaxa, is a star in the southern constellation Puppis. It has an apparent visual magnitude of 8.07,[2] which makes it too faint to be seen with the naked eye. Based upon parallax measurements made during the Gaia mission, it is located at a distance of 296 light-years (91 parsecs) from Earth.[1] It hosts two known planets, HD 48265 b and c.[9]This star appears close in the sky to Canopus, the second-brightest star in earth's sky, and is also a similar distance away. Because of this Canopus is the brightest star in the sky of Nosaxa's planets (other than Nosaxa itself), and, at magnitude -5.87 would appear far brighter than any star or planet seen from earth.[lower-alpha 1]

Nomenclature

HD 48265 is the star's designation in the Henry Draper Catalogue.

This was one of the systems selected to be named in the 2019 NameExoWorlds campaign during the 100th anniversary of the IAU, which assigned each country a star and planet to be named. This system was assigned to Argentina. HD 48265 is named Nosaxa 'springtime' and HD 48265 b Naqaỹa 'brother' in the Moqoit (Mocoví) language.[10][11]

Stellar properties

This star has a stellar classification of G5IV/V,[3] suggesting that, at an age of 4.8 billion years,[12] it has reached an intermediate evolutionary stage between a main sequence star and a subgiant. It has but 93% of the mass of the Sun,[5] while its outer atmosphere has begun to expand, reaching about 2.3 times the Sun's radius.[13] HD 48265 is radiating 62%[13] of the Sun's luminosity from its atmosphere at an effective temperature of 5,508 K,[12] giving it the yellowish glow of a G-type star.[14] Measurement of the chemical abundances of this star indicate that, compared to the Sun, it has a 95%[2] greater proportion of elements other than hydrogen and helium—what astronomers term the star's metallicity.

Planetary system

In October 2008 an exoplanet, HD 48265 b (later named Naqaỹa), was reported to be orbiting this star. This object was detected using the radial velocity method during an astronomical survey conducted by the Magellan Planet Search Program using the MIKE echelle spectrograph on the 6.5-m Magellan II (Clay) telescope.[5] A second planet was found in 2026 using a combination of radial velocity and astrometry. Both are gas giants more massive than Jupiter; they may be on mutually inclined orbits.[9]

The HD 48265 planetary system[9][lower-alpha 2]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b / Naqaỹa ≥1.67±0.06 MJ 1.87+0.02
−0.04 		789.6±1.1 0.35±0.02 11.7+11.0
−3.4 or 160.1+8.3
−31° 		—
c 4.45+0.75
−0.37 MJ 		10.4+1.6
−1.0 		10418+2451
−1412 		0.41+0.08
−0.06 		89±29° —

See also

  • List of extrasolar planets

Notes

  1. ↑ calculated using each star's distance, position in the sky, and brightness
  2. ↑ Planet b is listed with its minimum mass; including astrometric data suggests a larger true mass of 7.4+3.7
    −3.9     MJ    , but this is uncertain since this planet's astrometric signal is not significant.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 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.
  2. ↑ 2.0 2.1 2.2 2.3 Jenkins, J. S. et al. (July 2008), "Metallicities and activities of southern stars", Astronomy and Astrophysics 485 (2): 571–584, doi:10.1051/0004-6361:20078611, Bibcode: 2008A&A...485..571J 
  3. ↑ 3.0 3.1 Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode: 1978mcts.book.....H 
  4. ↑ 4.0 4.1 4.2 Cutri, R. M. et al. (June 2003), 2MASS All Sky Catalog of point sources, NASA/IPAC, Bibcode: 2003tmc..book.....C 
  5. ↑ 5.0 5.1 5.2 Minniti, Dante et al. (2009), "Low-Mass Companions for Five Solar-Type Stars From the Magellan Planet Search Program", The Astrophysical Journal 693 (2): 1424–1430, doi:10.1088/0004-637X/693/2/1424, Bibcode: 2009ApJ...693.1424M 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 Barbato, D. et al. (August 2018). "Exploring the realm of scaled solar system analogues with HARPS". Astronomy & Astrophysics 615: A175. doi:10.1051/0004-6361/201832791. Bibcode: 2018A&A...615A.175B. 
  7. ↑ 7.0 7.1 Jenkins, J. S. et al. (2017), "New planetary systems from the Calan–Hertfordshire Extrasolar Planet Search", Monthly Notices of the Royal Astronomical Society 466 (1): 443–473, doi:10.1093/mnras/stw2811, Bibcode: 2017MNRAS.466..443J 
  8. ↑ "HD 48265". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+48265. 
  9. ↑ 9.0 9.1 9.2 "Detection of four cold Jupiters through combined analyses of radial velocity and astrometry data". January 2026. arXiv:2601.11280 [astro-ph.EP].
  10. ↑ (in en) Argentina, http://www.nameexoworlds.iau.org/argentina, retrieved 2019-12-18 
  11. ↑ Javier Salas (2019-12-20), "Rosalía de Castro ya tiene su estrella", El País, https://elpais.com/elpais/2019/12/16/ciencia/1576499712_305941.html, retrieved 2020-01-06 
  12. ↑ 12.0 12.1 Nordström, B. et al. (May 2004), "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs", Astronomy and Astrophysics 418: 989–1019, doi:10.1051/0004-6361:20035959, Bibcode: 2004A&A...418..989N 
  13. ↑ 13.0 13.1 "HD 48265", NASA Exoplanet Archive (NASA), http://exoplanetarchive.ipac.caltech.edu/cgi-bin/Sieve/nph-sieve?mission=NStED&objectSearch&objstr=HD+48265, retrieved 2012-03-15 
  14. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, retrieved 2012-01-16 

Coordinates: Sky map 06h 40m 01.727s, −48° 32′ 31.04″



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