HD 7449
Binary star system in the constellation Cetus
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HD 7449 is a binary star system about 126 light-years way. The primary star, HD 7449 A, is a main-sequence star belonging to the spectral class F9.5. It is younger than the Sun. The primary star is slightly depleted of heavy elements, having 80% of solar abundance.[7]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cetus |
| Right ascension | 01h 14m 29.32229s[1] |
| Declination | −05° 02′ 50.6148″[1] |
| Apparent magnitude (V) | 7.50[2] |
| Characteristics | |
| Evolutionary stage | main sequence[1] |
| Spectral type | F9.5V[2] + M4.5[3] |
| B−V color index | 0.575±0.007[2] |
| Astrometry | |
| Radial velocity (Rv) | −19.60±0.13[1] km/s |
| Proper motion (μ) | RA: −164.544±0.039 mas/yr[1] Dec.: −134.382±0.028 mas/yr[1] |
| Parallax (π) | 25.9132±0.0287 mas[1] |
| Distance | 125.9 ± 0.1 ly (38.59 ± 0.04 pc) |
| Absolute magnitude (MV) | 4.55[2] |
| Orbit[4] | |
| Primary | HD 7449 A |
| Name | HD 7449 B |
| Period (P) | 175.310+43.633 −34.380 yr |
| Semi-major axis (a) | 34.7+5.5 −4.8 AU |
| Eccentricity (e) | 0.30+0.08 −0.10 |
| Inclination (i) | 68.4+4.1 −3.9° |
| Longitude of the node (Ω) | 326+3 −2° |
| Periastron epoch (T) | 2391480.709+12803.765 −15269.796 |
| Argument of periastron (ω) (secondary) | 201±13° |
| Semi-amplitude (K1) (primary) | 0.72+0.04 −0.03 km/s |
| Details | |
| HD 7449 A | |
| Mass | 1.051+0.054 −0.055[5] M☉ |
| Radius | 1.02±0.02[6] R☉ |
| Luminosity | 1.26±0.02[6] L☉ |
| Surface gravity (log g) | 4.44±0.02[6] cgs |
| Temperature | 6060±42[6] K |
| Metallicity | −0.11±0.01[7] |
| Age | 2.2±1.3[6] Gyr |
| HD 7449 B | |
| Mass | 0.111+0.028 −0.020[5] M☉ |
| Temperature | 3,000[6] K |
| Other designations | |
| BD−05 215, HD 7449, HIP 5806, TYC 4683-883-1, 2MASS J01142933-0502504[8] | |
| Database references | |
| SIMBAD | data |
Companion
The stellar companion HD 7449 B, belonging to spectral class M4.5, was discovered in 2015.[9] A survey in 2017 has failed to find additional stars with masses above 0.35M☉ in the system.[10]
The most recent parameters for HD 7449 B as of 2022 come from a combination of data from radial velocity, astrometry, and imaging, showing that it is about 178 MJ (0.17 M☉), and orbiting with a semi-major axis of about 34.7 AU and an orbital period of about 175 years.[4]
Planetary system
In 2011 one super-Jupiter-mass planet, HD 7449 Ab on a very eccentric orbit around HD 7449 A was discovered utilising the radial velocity method.[7] A second, long-term radial velocity trend is present, and a second planet or brown dwarf has been proposed as the cause of this trend.[7][11] However, in 2015 a low-mass stellar companion (HD 7449 B) was found, which is likely the cause of the long-term trend. The large eccentricity of the inner planet is likely caused by this stellar companion.[3] In 2022, the inclination and true mass of HD 7449 Ab were measured via astrometry.[4]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (years) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 8.174+3.055 −2.699 MJ |
2.438+0.062 −0.063 |
3.479+0.029 −0.020 |
0.752+0.035 −0.032 |
171.631+2.609 −3.740° |
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