HD 149026
From Wikipedia, the free encyclopedia
| Observation data Epoch 2000 (ICRS) |
|
|---|---|
| Constellation (pronunciation) |
Hercules |
| Right ascension | 16h 30m 29.619s [1] [2] |
| Declination | +38° 20' 50.31" [1] [2] |
| Apparent magnitude (V) | 8.15 [1] |
| Characteristics | |
| Spectral type | G0 IV |
| B-V color index | 0.611 [1] |
| Variable type | none |
| Astrometry | |
| Radial velocity (Rv) | -18.1 [3] km/s |
| Proper motion (μ) | RA: -77.12 [1] mas/yr Dec.: 53.34 [1] mas/yr |
| Parallax (π) | 12.68 ± 0.79 [1] mas |
| Distance | 257 ly (78.9 ± 6.6 [4] pc) |
| Absolute magnitude (MV) | 3.66 [4] |
| Details | |
| Mass | 1.31 ± 0.1 [4] M☉ |
| Radius | 1.45 ± 0.1 [4] R☉ |
| Luminosity | 2.72 ± 0.5 [4] L☉ |
| Temperature | 6147 ± 50 [4] K |
| Metallicity | 200% - 260% [4] |
| Age | (2.0 ± 0.8) × 109 [4] years |
| Other designations | |
|
BD+38°2787, HIP 80838 [2]
|
|
| Database references | |
| SIMBAD | data |
HD 149026 is an 8th magnitude star in constellation Hercules. The star is classified as a yellow subgiant (spectral type G0 IV). It is slightly 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, 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. 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.[5]
| Planet | Mass (MJ) |
Semimajor axis (AU) |
Orbital period (days) |
Eccentricity |
|---|---|---|---|---|
| b | 0.36 ± 0.03 | 0.042 | 2.8766 ± 0.001 | 0 (fixed) |
[edit] External links
- Extrasolar Planets Encyclopaedia entry — URL accessed on May 7, 2006
- N2K Information For Star HD149026 from N2K Consortium — URL accessed on May 7, 2006
- One Big Ball of Rock — Sky & Telescope magazine — URL accessed on May 7, 2006
- Amateur Detects New Transiting Exoplanet — Sky & Telescope magazine — URL accessed on May 7, 2006
[edit] References
- ^ a b c d e f g entry for HD 149026 (Hipparcos) Accessed on line December 24, 2007
- ^ a b c entry for HD 149026 (SIMBAD) Accessed on line December 24, 2007
- ^ entry for HD 149026 (Geneva-Copenhagen Survey of Solar neighbourhood) Accessed on line December 24, 2007
- ^ a b c d e f g h i j Sato 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. doi:.
- ^ Imaginova, Sizzling Hot Planet Makes Some Stars Look Cool (5/9/07).
