HD 149026
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Hercules |
| Right ascension | 16h 30m 29.620s[1] |
| Declination | +38° 20′ 50.31″[1] |
| Apparent magnitude (V) | 8.15 |
| Characteristics | |
| Spectral type | G0IV[2] |
| Apparent magnitude (B) | 8.76[2] |
| B−V color index | 0.611 |
| Astrometry | |
| Radial velocity (Rv) | –18.1 ± 0.4[2] km/s |
| Proper motion (μ) | RA: –76.27 ± 0.54[1] mas/yr Dec.: 53.07 ± 0.69[1] mas/yr |
| Parallax (π) | 12.59 ± 0.70[1] mas |
| Distance | 260 ± 10 ly (79 ± 4 pc) |
| Absolute magnitude (MV) | 3.65 ± 0.12[3] |
| Details | |
| Mass | 1.345 ± 0.020[3] M☉ |
| Radius | 1.541 +0.046 −0.042[3] R☉ |
| Luminosity | 3.03 +0.20 −0.18[3] L☉ |
| Surface gravity (log g) | 4.189 +0.020 −0.021[3] cgs |
| Temperature | 6147 ± 50[4] K |
| Metallicity [Fe/H] | 0.36 ± 0.05[4] dex |
| Rotational velocity (v sin i) | 6.0 ± 0.5[4] km/s |
| Age | 2.6 +0.3 −0.2[3] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| Extrasolar Planets Encyclopaedia | data |
HD 149026 is a yellow subgiant star approximately 260 light-years away in the constellation of Hercules. The star is thought to be much more massive, larger, and brighter than the Sun. As of 2005, an extrasolar planet has been confirmed to be orbiting the star. The name of this star comes from its identifier in the Henry Draper Catalog.[2]
The star
The star is thought to be much more massive, larger, and brighter than the Sun. The higher mass of the star causes that despite considerably younger age (2.0 Ga) it is already much more evolved than the Sun. The internal fusion of hydrogen in the core of the star is coming to an end, and it is beginning to evolve towards red gianthood. HD 149026 is about 260 light-years distant,[1] which means the star is not visible to the unaided eye. However, it should be an easy target to binoculars or a small telescope.[4]
The star is over twice as enriched with chemical elements heavier than hydrogen and helium as the Sun. Because of this and the fact that the star is relatively bright, a group of astronomers in N2K Consortium began to study the star. The star's anomalous composition as measured may be surface pollution only, from the intake of heavy-element planetesimals.[5]
Planetary system
In 2005 they discovered an unusual extrasolar planet orbiting the star. The planet, designated HD 149026 b, was detected transiting the star allowing its diameter to be measured. It was found to be smaller than other known transiting planets, meaning the planet is unusually dense for a closely orbiting giant planet.[4] The temperature of the giant planet is calculated to be 3,700 °F (2,040 °C), generating so much infrared heat that it glows. Scientists believe the planet absorbs nearly all the sunlight and radiates it into space as heat.[6]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 0.36 ± 0.03 MJ | 0.042 | 2.8766 ± 0.001 | 0 | — | — |
See also
- 51 Pegasi
- List of extrasolar planets
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.Vizier catalog entry
- ↑ 2.0 2.1 2.2 2.3 "SIMBAD query result: HIP 80838 -- Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2009-05-20.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Carter, Joshua A. et al. (2009). "Near-Infrared Transit Photometry of the Exoplanet HD 149026b". The Astrophysical Journal 696 (1): 241–253. arXiv:0902.1542. Bibcode:2009ApJ...696..241C. doi:10.1088/0004-637X/696/1/241.
- ↑ 4.0 4.1 4.2 4.3 4.4 Sato, Bun'ei et al. (2005). "The N2K Consortium. II. A Transiting Hot Saturn around HD 149026 with a Large Dense Core". The Astrophysical Journal 633 (1): 465–473. arXiv:astro-ph/0507009. Bibcode:2005ApJ...633..465S. doi:10.1086/449306.
- ↑ S.-L. Li, D. N. C. Lin, and X.-W. Liu (2008). "Extent of pollution in planet-bearing stars". The Astrophysical Journal 685 (2): 1210–1219. arXiv:0802.2359v1. Bibcode:2008ApJ...685.1210L. doi:10.1086/591122.
- ↑ Imaginova, Sizzling Hot Planet Makes Some Stars Look Cool (5/9/07).
External links
- "N2K Information For Star HD149026". San Francisco State University. N2K Consortium. Retrieved 2008-06-22.
- Naeye, Robert (2005-07-07). "Amateur Detects New Transiting Exoplanet". Sky & Telescope. Retrieved 2008-06-22.
- Naeye, Robert (2005-07-08). "One Big Ball of Rock". Sky & Telescope. Retrieved 2008-06-22.
Coordinates: 
16h 30m 29.619s, +38° 20′ 50.31″
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