14 Herculis b
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| Extrasolar planet | List of extrasolar planets | |
|---|---|---|
| Parent star | ||
| Star | 14 Herculis | |
| Constellation | Hercules | |
| Right ascension | (α) | 16h 10m 23.59s |
| Declination | (δ) | +43° 49′ 18.2″ |
| Distance | 59.0 ly (18.1 pc) | |
| Spectral type | K0V | |
| Orbital elements | ||
| Semimajor axis | (a) | 2.77 ± 0.05[1] AU |
| Eccentricity | (e) | 0.369 ± 0.005[1] |
| Orbital period | (P) | 1773.4 ± 2.5[1] d |
| Angular distance | (θ) | 153 mas |
| Longitude of periastron |
(ω) | 22.6 ± 0.9[1]° |
| Time of periastron | (T0) | 2,451,372.7 ± 3.6[1] JD |
| Semi-amplitude | (K) | 90.0 ± 0.5[1] m/s |
| Physical characteristics | ||
| Mass | (m) | >4.64 ± 0.19[1] MJ |
| Discovery information | ||
| Discovery date | July 6, 1998 | |
| Discoverer(s) | Naef et al. | |
| Detection method | Doppler Spectroscopy | |
| Discovery site | Switzerland | |
| Discovery status | Published | |
14 Herculis b is an extrasolar planet orbiting 14 Herculis. Based on its mass, it is most likely a gas giant roughtly the same size as Jupiter but much more massive. It was discovered in July 1998 by the Geneva Extrasolar Planet Search team.[2][3] At the time of discovery was the extrasolar planet with the longest orbital period, though longer-period planets have subsequently been discovered.
Contents |
[edit] Discovery
Like the majority of known extrasolar planets, 14 Herculis b was detected by measuring variations in its star's radial velocity as a result of the planet's gravity. This was done by making precise measurements of the Doppler shift of the spectrum of 14 Herculis. Prior to this analysis, another possible explanation of previous Doppler shift analysis included face-on spectroscopic binaries.[3]
[edit] Orbit and mass
Preliminary astrometric measurements made by the Hipparcos satellite suggest that this planet has an orbital inclination of 155.3° with respect to plane of the sky, which would imply a true mass of 11.1 times that of Jupiter, close to the deuterium-burning threshold that some astronomers use to define the distinction between a planet and a brown dwarf.[4] However subsequent analysis suggests that the Hipparcos measurements were not precise enough to accurately determine the orbits, so the actual inclination and true mass of the planet remains unknown.[5] Future astrometric missions such as Gaia and Space Interferometry Mission can precisely measure its inclination of the orbit and hence the true mass.
[edit] Direct imaging
Because of the wide separation between this planet and its host star, and the proximity of the 14 Herculis system to the Sun, it is a promising candidate for direct imaging of the planet, as the angular separation is predicted to be large. However, a search made using the adaptive optics CFHT 3.60m telescope on Mauna Kea did not make such a detection, suggesting the object is not a star or a brown dwarf, but of planetary mass (more massive objects would be more luminous and hence easier to detect).[6] Future space missions such as New Worlds Mission can directly image this planet and determine its radius, mass, orbit, and atmospheric characteristics.
[edit] References
- ^ a b c d e f g Wittenmyer, R. A., Endl, M., Cochran, W. D. (2007). "Long-Period Objects in the Extrasolar Planetary Systems 47 Ursae Majoris and 14 Herculis". The Astrophysical Journal 654 (1): 625 – 632. doi:.
- ^ Mayor, M. et al. (1998). "Searching for giant planets at the Haute-Provence Observatory" in IAU Colloqu. 170. (ed. Hearnshaw, J. B. and Scarfe, C. D.) Precise Stellar Radial Velocities, San Francisco: ASP.
- ^ a b Dominique Naef, Michel Mayor, Jean-Luc Beuzit, Christian Perrier, Didier Queloz, Jean-Pierre Sivan, and Stephane Udry. Extrasolar Planetary Systems or Spectroscopic Binaries? Discrimination using Spectral Line Properties. Retrieved on 2007-09-10.
- ^ Han, I. et al. (2001). "Preliminary Astrometric Masses for Proposed Extrasolar Planetary Companions" ([dead link] – Scholar search). The Astrophysical Journal 548: L57 – L60. doi:.
- ^ Pourbaix, D. and Arenou, F. (2001). "Screening the Hipparcos-based astrometric orbits of sub-stellar objects". Astronomy and Astrophysics 372: 935 – 944. doi:.
- ^ 14 Herculis: A new extrasolar planet discovered at the Haute Provence Observatory. Retrieved on 2007-07-28.
