A star chart of the constellation of Orion showing the position of HD 43587 (circled) | |
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Orion |
HD 43587 Aab | |
Right ascension | 06h 17m 16.139s ± 3.26 [1] |
Declination | +05° 06′ 00.40″ ± 2.46 [1] |
Apparent magnitude (V) | 5.70 |
HD 43587 BC | |
Right ascension | 06h 17m 10.65s |
Declination | +05° 07′ 02.4″ |
Apparent magnitude (V) | 13.27 (BC total) |
Characteristics | |
Spectral type | G0V [2] [3] / M0V [3] [4] / M3.5V [5] / M5V [5] |
B−V color index | 0.610 [1] (system total) |
Astrometry | |
HD 43587 Aa | |
Radial velocity (Rv) | 8.96 ± 0.10 [note 1] km/s |
Proper motion (μ) | RA: -187.72 ± 0.37 [1] mas/yr Dec.: 170.69 ± 0.28 [1] mas/yr |
Parallax (π) | 51.95 ± 0.40 mas [1] |
Distance | 62.8 ± 0.5 ly (19.2 ± 0.1 pc) |
HD 43587 BC | |
Proper motion (μ) | RA: -198 mas/yr Dec.: 164 mas/yr |
Parallax (π) | 55.2 ± 1.0 mas [5] |
Distance | 59 ± 1 ly (18.1 ± 0.3 pc) |
Absolute magnitude (MV) | 12.07 ± 0.07 / 14.90 ± 0.21 |
Orbit [6] | |
Primary | HD 43587 Aa |
Companion | HD 43587 Ab |
Period (P) | 32.07 years |
Semi-major axis (a) | 0.598″ |
Eccentricity (e) | 0.796 |
Inclination (i) | 35.6° |
Longitude of the node (Ω) | 163.1° |
Periastron epoch (T) | 1998.05 |
Argument of periastron (ω) (secondary) | 75.0° |
Semi-amplitude (K1) (primary) | 4.323 ± 0.009 [7] km/s |
Position (relative to HD 43587 B) [5] | |
Component | HD 43587 C |
Epoch of observation | 2453376.0 |
Angular distance | 366 ± 3 mas |
Position angle | 158 ± 1° |
Details | |
Mass | 1.049 ± 0.016 [2] / 0.67 ± 0.04 [4] [note 2] / 0.25 ± 0.06 [5] / 0.12 ± 0.02 [5] M☉ |
Radius | 1.15 ± 0.01 [2] R☉ |
Surface gravity (log g) | 4.30 ± 0.01 [2] cgs |
Temperature | 5947 ± 17 [2] K |
Metallicity [Fe/H] | -0.02 ± 0.02 [2] dex |
Age | 4.97 ± 0.52 [2] Gyr |
Other designations | |
HIP 29860, Gliese 231.1, HR 2251 | |
HD 43587 Aab: WDS J06173+0506Aa,Ab, LEP 24A | |
HD 43587 BC: NLTT 16333, [note 3] WDS J06173+0506E, LEP 24AE | |
Database references | |
SIMBAD | data |
HD 43587 is a stellar system approximately 63 light-years away in the constellation of Orion, visible to the naked eye. The system comprises four individual stars, with two widely separated binaries forming a quadruple system.
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HD 43587, being a bright, nearby, high proper motion solar-type star, has been fairly extensively studied. The star was found to be slightly hotter than the Sun, but has a similar metallicity and is therefore not much more massive.
Searches for companions to the star, among many other stars, were ongoing throughout the last century. HD 43587 did not seem to have a variable radial velocity or much variability in its astrometry which would indicate that it had a close companion. The Washington Double Star Catalog lists four visual companions; companion B, discovered in 1891, has differing proper motion to the primary, so it is unrelated. Companions C and D, discovered in 1911, have only been observed once, making their relationship uncertain at best. However, Companion E, first observed in 1990, has very similar proper motion to the primary, meaning that it is indeed a companion. Designated HD 43587 B, the star was found to be a faint M-dwarf.
Because of the star's brightness and position in the vicinity of the constellation of Monoceros, HD 43587 A was selected as one of the primary COROT astroseismology targets, which would collect information on the star's internal properties.
Since the primary star is similar to the Sun and did not seem to have a close companion, it was targeted by the radial velocity-based planet searches that began at the end of the twentieth century. In particular, HD 43587 A was observed with the Keck/HIRES spectrograph. [8] However, during 1998 the star's radial velocity was found to decrease by about eight km/s, indicative of a long period stellar companion. An orbital fit found that this new companion has an orbital period of about 30 years, but on a very eccentric path which brings it through periastron in about a year. This third star, designated HD 43587 Ab, was found to have a minimum mass of about 0.3 M☉
The long period of HD 43587 Ab coupled with the system being close to the Solar System means that the two components of the primary system would be well separated as viewed from Earth, which made it an attractive target for resolving. This was achieved in 2006 with adaptive optics, [4] and has been achieved since with speckle interferometry. [6]
Meanwhile, HD 43587 B became interesting because it was a little-studied, fairly bright M-dwarf. As of such, it was targeted in the STEPS astrometric survey, [5] which found that the star's motion was deviating from linear motion; adaptive optics observations confirmed that HD 43587 B was itself a binary with a fourth component, HD 43587 C. While the orbital period of the binary was too long to constrain the two components' dynamical masses, photometric analysis found that they were both late M-dwarfs.
HD 46375 is double star with an exoplanetary companion in the equatorial constellation of Monoceros. It presents as an 8th-magnitude star with an apparent visual magnitude of 7.91, which is too dim to be readily visible to the naked eye. The system is located at a distance of 96.5 light-years from the Sun based on parallax measurements, but is slowly drifting closer with a radial velocity of −1 km/s. The common proper motion stellar companion, designated HD 46375 B, has a linear projected separation of 346±13 AU.
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HD 222582 is a multiple star system in the equatorial constellation of Aquarius. It is invisible to the naked eye with an apparent visual magnitude of 7.7, but can be viewed with binoculars or a small telescope. The system is located at a distance of 138 light years from the Sun based on parallax, and it is drifting further away with a radial velocity of +12 km/s. It is located close enough to the ecliptic that it is subject to lunar occultations.
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HD 126614 is a trinary star system in the equatorial constellation of Virgo. The primary member, designated component A, is host to an exoplanetary companion. With an apparent visual magnitude of 8.81, it is too faint to be seen with the naked eye. The system is located at a distance of 239 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −33 km/s.
HD 24496 is a binary star system in the equatorial constellation of Taurus. The combined apparent visual magnitude of the pair is 6.81, which is too faint to be readily visible to the normal human eye. The system is located at a distance of 66.8 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +19 km/s. It is traversing the celestial sphere with a proper motion of 0.276″ per year.
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Kappa Fornacis is a star system that lies approximately 72 light-years away. The system consists of a somewhat evolved primary orbited by a massive, 'dark' secondary that is actually itself a close red dwarf binary, making a hierarchal triple system.
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