HD 27894 - star in the constellation Grid . It is located about 138 light years from the Sun. Around the star are turning at least three planets .
| HD 27894 | |||
|---|---|---|---|
| Star | |||
  | |||
| Observational data ( Epoch J2000.0 ) | |||
| Type of | Single star | ||
| Right ascension | |||
| Declination | |||
| Distance | 138.1 sv. years (42.37 pc ) [1] | ||
| Visible magnitude ( V ) | 9.36 [1] | ||
| Constellation | Grid | ||
| Astrometry | |||
| Radial velocity ( R v ) | 82.91 [2] km / s | ||
| Proper motion (μ) | RA: 182.16 [2] mas per year Dec: 271.77 [2] mas per year | ||
| Parallax (π) | 22.79 ± 0.85 [2] mas | ||
| Absolute magnitude (V) | 6.225 [1] | ||
| Specifications | |||
| Spectral class | K2V [2] | ||
| Color Indicator ( B - V ) | 1.003 [1] | ||
| physical characteristics | |||
| Weight | 0.8 [3] M ☉ | ||
| Radius | 0.83 [3] R ☉ | ||
| Age | 3.9 billion [1] years | ||
| Temperature | 4875 [3] K | ||
| Luminosity | 0.356 [1] L ☉ | ||
| Metallicity | [Fe / H] = + 0.30 ± 0.07 [1] | ||
| |||
| Information in databases | |||
| SIMBAD | data | ||
| Sources: [2] | |||
Content
Characteristics
HD 27894 is a star of 9.36 visible magnitude, which is not visible to the naked eye. It can be found in the sky in the western part of the constellation Grid, next to the star ε Grid . It is first mentioned in the Henry Draper catalog compiled at the beginning of the 20th century . This is the orange dwarf of the main sequence, having a mass and radius equal to 80% and 83% of the sun, respectively. [3] HD 27894 is a relatively quiet star with almost no chromospheric activity. The temperature of its surface is about 4875 Kelvin . The star's luminosity is 0.356 solar. The star's age is estimated at about 3.9 billion years. [one]
Planetary system
In 2005, a group of astronomers working with the HARPS spectrograph announced the discovery of the first planet HD 27894 b in the system [1] . It has a mass equal to 66% of the mass of Jupiter and makes one revolution around the parent star for more than 18 days. In 2017, two more planets were discovered: HD 27894 c and HD 27894 d . [5] Like planet HD 27894 b , they belong to the class of gas giants. However, if the planets b and c are very close to the parent star, then the orbit of the planet d is located at a distance of 5.45 AU. from the luminary. The authors of the discovery created a computer model of the motion of all three planets for a period of up to 10 million years, and concluded that the entire system is dynamically stable.
Discoveries of all planets were made by the method of Doppler spectroscopy . Below is a summary table of their characteristics.
| Planet | Weight ( M J ) | Radius ( R j ) | Period of treatment ( days ) | Big axis orbits ( au ) | Eccentricity orbits |
|---|---|---|---|---|---|
| b | 0.665 | - | 18.02 | 0.125 | 0.047 |
| c | 0.162 | - | 36.07 | 0.198 | 0.015 |
| d | 5.4 | - | 5174 | 5.45 | 0.39 |
Notes
- ↑ 1 2 3 4 5 6 7 8 9 Moutou, C. et al. The HARPS search for the southern extra-solar planets. Iv. Three close-in planets around HD 2638, HD 27894 and HD 63454 (English) . Astronomy and Astrophysics (08/2005). The appeal date is June 7, 2017.
- ↑ 1 2 3 4 5 6 SIMBAD (English) . - HD 27894 in SIMBAD database . The appeal date is June 7, 2017.
- ↑ 1 2 3 4 E. Plávalová. Taxonomy of the extrasolar planet (English) . Arxiv.org (Apr 11 2012). The appeal date is June 7, 2017.
- ↑ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 SIMBAD Astronomical Database
- ↑ T. Trifonov et al. Three planets around HD 27894. A close-in pair with a 2: 1 period ratio an eccentric Jovian planet at 5.4 AU . Arxiv.org (1 Jun 2017). The appeal date is June 7, 2017.
See also
- List of stars in the Grid constellation