Epoch J2000 Equinox J2000
|Right ascension||02h 34m 11.04689s|
|Declination||−12° 23′ 3.4570″|
|Apparent magnitude (V)||9.85|
|Spectral type||F2V-IV[note 1]|
|Apparent magnitude (B)||10.18|
|Apparent magnitude (V)||9.85|
|Apparent magnitude (J)||8.790|
|Apparent magnitude (H)||8.516|
|Apparent magnitude (K)||8.457|
|Radial velocity (Rv)||23.62 km/s|
|Proper motion (μ)||RA: 57.27 mas/yr
Dec.: -187.74 mas/yr
|Parallax (π)||8.93 mas|
|Mass||0.83 ± 0.05 M☉|
|Radius||1.6 ± 0.1 R☉|
|Temperature||6040 ± 210 K|
|Metallicity [Fe/H]||–1.95 ± 0.09[note 2] dex|
|Age||12.8 ± 2.6 Gyr|
HIP 11952 is a star in the Milky Way galaxy, located 375 light-years away from the Sun. While the spectral lines strongly indicate that the star is of spectral type F2V-IV, previous analyses have stated that the star is a G8III giant star and an F0V main-sequence star. Located in the constellation Cetus, the star has a metallicity only 1% that of the Sun. It is nearing the end of its lifetime on the main sequence, and will soon begin the transition into a red giant.
Claims of planet detection
In 2012 it was announced that HIP 11952 had two giant planets, this would have made it the oldest and most metal-poor planet host star known. This would have posed a challenge to planetary formation, as the chances of a planet forming so early in the Universe's history, with such a small amount of heavy elements with which to form planets, are believed to be remote.
Further measurements of HIP 11952 were made on 35 nights over about 150 days, from August 7, 2012 to January 6, 2013, using the newly installed high resolution spectrograph HARPS-N at the 3.58m Telescopio Nazionale Galileo telescope on La Palma Island (Canary Islands) and HARPS at the European Southern Observatory's 3.6m telescope on La Silla (Chile). Following their analysis, they were able to confidently exclude, through non-detection, the presence of the two giant planets with periods of 6.95 ± 0.01 days and 290.0 ± 16. 2 days. They also reasoned that the previously mistaken detections were probably due to instrument measurement errors. Re-analysis of the FEROS data revealed a problem with the barycentric correction used to derive the radial velocities, this error had led to the erroneous detection claim.
- Staff, Space.com (28 March 2012). "Ancient Alien Planets Shake Up View of Early Universe". Space.com. Space.com. Retrieved March 29, 2012.
- "HD 16031". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved March 29, 2012.
- "Planetary companions around the metal-poor star HIP 11952" (PDF). Astronomy and Astrophysics. 540: A141. March 2012. arXiv: . Bibcode:2012A&A...540A.141S. doi:10.1051/0004-6361/201117826.
- Schneider, Jean (23 March 2012). "Notes for Star HIP 11952". Extrasolar Planets Encyclopedia. Retrieved March 29, 2012.
- Than, Ker (26 March 2012). "Oldest Alien Planets Found—Born at Dawn of Universe". National Geographic Daily News. National Geographic. Retrieved March 29, 2012.
- O'Neill, Ian (27 March 2012). "Most ancient, 'Impossible' Alien Worlds Discovered". Discovery News. Discovery News. Retrieved March 29, 2012.
- Desidera, S; et al. (June 2013). "The GAPS programme with HARPS-N at TNG. II. No giant planets around the metal-poor star HIP 11952". Astronomy and Astrophysics. 554: 29–33. arXiv: . Bibcode:2013A&A...554A..29D. doi:10.1051/0004-6361/201321155.
- Müller, A.; Roccatagliata, V.; Henning, Th.; Fedele, D.; Pasquali, A.; Caffau, E.; Rodríguez-Ledesma, M. V.; Mohler-Fischer, M.; Seemann, U.; Klement, R. J. (2013). "Reanalysis of the FEROS observations of HIP 11952". Astronomy and Astrophysics. 556: id.A3. arXiv: . Bibcode:2013A&A...556A...3M. doi:10.1051/0004-6361/201321497.
- The stellar classification for this star is uncertain; please read the cited paper for more information.
- This measurement indicates the log10 of the relative abundance of iron in the measured star to that of the Sun.