HIP 11952
An artist's conception of the HIP 11952 system. | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cetus[1] |
| Right ascension | 02h 34m 11.04689s[2] |
| Declination | −12° 23′ 3.4570″[2] |
| Apparent magnitude (V) | 9.85 |
| Characteristics | |
| Spectral type | F2V-IV[3][4][note 1] |
| Apparent magnitude (B) | 10.18[2] |
| Apparent magnitude (V) | 9.85[2] |
| Apparent magnitude (J) | 8.790[2] |
| Apparent magnitude (H) | 8.516[2] |
| Apparent magnitude (K) | 8.457[2] |
| Astrometry | |
| Radial velocity (Rv) | 23.62[2] km/s |
| Proper motion (μ) | RA: 57.27[2] mas/yr Dec.: -187.74[2] mas/yr |
| Parallax (π) | 8.93[2] mas |
| Distance | 376.1 ly (115.3[3] pc) |
| Details | |
| Mass | 0.83 ± 0.05[4] M☉ |
| Radius | 1.6 ± 0.1[3] R☉ |
| Temperature | 6040 ± 210[4] K |
| Metallicity [Fe/H] | –1.95 ± 0.09[3][note 2] dex |
| Age | 12.8 ± 2.6[4] Gyr |
| Other designations | |
The star is nearing the end of its lifetime on the main sequence, and will soon begin the transition into a red giant.[5]
Planetary system
The star HIP 11952 has two planets; the more massive outer planet, HIP 11952 b, in a somewhat eccentric[4] orbit of 290 days, and a less massive hot Jupiter, HIP 11952 c, in an eccentric seven-day orbit around its host star.[4] This system contains two defining characteristics: the star is the oldest one confirmed to possess a planetary system, and due to the age of the system, the star has the lowest metallicity of any found with planets orbiting it.[5][note 3] 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.[6] In spite of this, the star has an exceptionally high metallicity among those that formed at the same time in the Universe's history.[6]
While the discoverers leave open the possibility of the planets forming billions of years after their host stars, once the Universe had a far greater concentration of heavier elements, they state that the chance of this happening is, according to the authors of the discovery paper, extremely small.[5] In the future, as the host star eventually transforms into a red giant, then dies as a white dwarf, the planets may become stripped of all but their cores, like the planets of the KOI-55 system.[5]
The planets may not, owing to the lack of elements heavier than hydrogen and helium, be an ideal location to extend the search for extraterrestrial life, but would probably be more scientifically valuable as a captured moment of the Universe's earliest history.[6]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| c | 0.78 ± 0.16 MJ | 0.07 ± 0.01 | 6.95 ± 0.01 | 0.35 ± 0.24 | — | — |
| b | 2.93 ± 0.42 MJ | 0.81 ± 0.02 | 290 ± 16.2 | 0.27 ± 0.1 | — | — |
Astronomers have recently performed radial velocity monitoring of HIP 11952 on 35 nights over about 150 days, from August 7th 2012 to January 6th 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.[7] They also reasoned that the previously mistaken detections were probably due to instrument measurement errors.[7]
See also
- KOI-55
- Population II star
- Extrasolar planet
- Dubious and disproven exoplanets
References
- ↑ Staff, Space.com (28 March 2012). "Ancient Alien Planets Shake Up View of Early Universe". Space.com. Space.com. Retrieved March 29, 2012.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 "Basic data : LP 710-89 -- High proper-motion Star". SIMBAD. University of Stratsbourg. 2011. Retrieved March 29, 2012.
- ↑ 3.0 3.1 3.2 3.3 3.4 "Planetary companions around the metal-poor star HIP 11952". Astronomy and Astrophysics. March 2012.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Schneider, Jean (23 March 2012). "Notes for Star HIP 11952". Extrasolar Planets Encyclopedia. Retrieved March 29, 2012.
- ↑ 5.0 5.1 5.2 5.3 5.4 Than, Ker (26 March 2012). "Oldest Alien Planets Found—Born at Dawn of Universe". National Geographic Daily News. National Geographic. Retrieved March 29, 2012.
- ↑ 6.0 6.1 6.2 O'Neill, Ian (27 March 2012). "Most ancient, 'Impossible' Alien Worlds Discovered". Discovery News. Discovery News. Retrieved March 29, 2012.
- ↑ 7.0 7.1 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:1302.3093. Bibcode:2013A&A...554A..29D. doi:10.1051/0004-6361/201321155.
Notes
| ||||||||||||||||||||||||||