Gliese 900
Hierarchical triple star system in the constellation Pisces
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Gliese 900 (GJ 900, BD+00 5017) is a triple star system, located 68 light-years from Earth in the constellation Pisces. It is made up of three main sequence stars: one is a K-type star, the two others are M-dwarf stars. The two M-dwarfs form a binary system with a period of 36 years, and this system has a period of 80 years around the primary component. With an apparent magnitude of 9.546, Gliese 900 is not visible to the naked eye. A widely separated planet has been detected around the system.[8]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Pisces[1] |
| Right ascension | 23h 35m 00.27674s[2] |
| Declination | +01° 36′ 19.4347″[2] |
| Apparent magnitude (V) | 9.546[3] |
| Characteristics | |
| A | |
| Evolutionary stage | Main sequence[2] |
| Spectral type | K5-7[4] |
| B−V color index | 1.35[5] |
| B | |
| Evolutionary stage | Main sequence[4] |
| Spectral type | M3-4[4] |
| C | |
| Evolutionary stage | Main sequence[4] |
| Spectral type | M5-6[4] |
| Astrometry | |
| Radial velocity (Rv) | −10.44±0.44[2] km/s |
| Proper motion (μ) | RA: 340.029 mas/yr[2] Dec.: 28.456 mas/yr[2] |
| Parallax (π) | 47.9641±0.0236 mas[2] |
| Distance | 68.00 ± 0.03 ly (20.85 ± 0.01 pc) |
| Absolute magnitude (MV) | 7.95[a] |
| Details | |
| A | |
| Mass | 0.64 – 0.67[4] M☉ |
| Radius | 0.716±0.021[6] R☉ |
| Luminosity | 0.12±0.005[2] L☉ |
| Temperature | 4,079±180[4] K |
| Metallicity [Fe/H] | 0.02[7] dex |
| Rotation | 11.9[8] days |
| Age | 200±50[8] Myr |
| B | |
| Mass | 0.28 – 0.34[4] M☉ |
| C | |
| Mass | 0.16 – 0.24[4] M☉ |
| Orbit | |
| Primary | A |
| Name | BC |
| Period (P) | ≈80[4] yr |
| Orbit[7] | |
| Primary | B |
| Name | C |
| Period (P) | 36 yr |
| Semi-major axis (a) | 444 mas (9.217 AU)[b] |
| Eccentricity (e) | 0.136 |
| Inclination (i) | 82.21° |
| Argument of periastron (ω) (secondary) | 109.8° |
| Position (relative to A)[4] | |
| Epoch of observation | December 2006 |
| Angular distance | 751 (A–B) 708 (A–C) 51 (B–C) mas |
| Position angle | 342.5 (A–B) 344.7 (A–C) 130.3 (B–C)° |
| Other designations | |
| BD+00 5017, GJ 900, HIP 116384, WDS J23350+0136A,BC, G 29-47 / 157-46, LSPM J2235+0136, TIC 422618003, TYC 585-236-1, GSC 00585-00236, 2MASS J23350028+0136193, WISE J233500.50+013619.7[9] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
Stellar system
Gliese 900 is a hierarchical star system, made up of three main sequence stars: The primary component (Gliese 900 A) is a K5-K7 type star, that has 0.64–0.67 times the mass of the Sun,[4] 0.72 times its radius,[6] and 12% its luminosity.[2] A light curve from the Transiting Exoplanet Survey Satellite (TESS) shows that its rotational period is 12 days.[8] Gliese 900 A has a high level of chromospheric and coronal activity, although its apparent brightness presents little variation.[10] The other components are red dwarf stars. Gliese 900 B has a spectral type of M3–M4 and a mass between 0.24 and 0.34 solar masses. Gliese 900 C has a spectral type of M5–M6 and a mass between 0.16 and 0.24 solar masses.[4]
The system is young, about 200 million years old, and is a likely member (99.7% probability) of the nearby moving group Carina-Near.[11] It is a source of X-ray emission, with an observed flux of 9.13×102 mW M-2, and is also a source of ultraviolet emission.[8] The emission of X-rays is typical of young stars, and classifies it as one.[10] The TESS light curve identifies stellar flares on this star.[8]
Orbit
Gliese 900 B and C form an inner pair (named Gliese 900 BC) with an orbital period of around 36 years.[7] Gliese 900 BC and Gliese 900 A orbit the system's center of mass with a period of 80 years.[4][8] As of November 2004,[update] B was separated from A by 751 milliarcseconds and C was separated from A by 708 mas. This separation changes over time.[4] It was identified as a multiple star system in 2002 by Eduardo L. Martín, using adaptive optics-corrected images at the 8.2 m Subaru Telescope. When first observed, the A–B and A–C separations were of 0.51 and 0.76 arcsecs respectively.[10] A further study by Malogolovets et al. (2007) identified this system as a hierarchical triple.[4]
Other stars in the system
Malogolovets et al. (2007) reported two other objects in 2MASS images (potentially late red dwarfs) that would be the components D and E and make the system quintuple, being "very likely" to be bound to the system.[4] However, these faint stars haven't been confirmed as members of the GJ 900 system, and are likely not associated.[8]
Motion
Gliese 900 is located 68 light-years from Earth, based on parallax measurements by the Gaia spacecraft.[2] The BP-RP spectra suggest a distance of 67.7 ly.[2] The space velocity components of this system are U = −28.7, V = −15 and W = 0.2.[12] Gliese 900 is part of the thin disk population of the Milky Way.[12][4] It was once classified as part of the IC 2602 supercluster.[10] A newer analysis using kinematics from the Gaia spacecraft suggest that Gliese 900 has a 99.7% chance of being a member of the Carina-Near moving group and a 0.3% chance of being a field star, i.e. not associated to any star cluster or stellar association.[8]
Planetary system
A 2024 study led by Austin Rothermich identified CWISE J233531.55+014219.6 (abbreviated to CW2335+0142) as a proper motion companion to Gliese 900, with 99.5% probability.[8] This object, also called Gliese 900 b or Gliese 900 (ABC)b,[13][14] is a planetary-mass object that has 10.5 times the mass of Jupiter (0.01 times the mass of the Sun), a spectral type T9[8] and a temperature of 500 K.[15] It was found to be at an angular separation of 587" from Gliese 900. At the estimated distance to this system, it translates to a projected separation of 12,000 AU.[8]
As of 2024[update], Gliese 900 b has the largest observed separation of any known planet, and assuming a circular orbit, the longest orbital period.[16][17][c] The orbital period is estimated at 1.27 million years based on the projected separation.[18] Due to the similar spectral type, orbital separation and age, Gliese 900 b has been compared to COCONUTS-2b by the discovery team.[8]
Also in 2024, a study using data from Wide-field Infrared Survey Explorer found a red W2-W3 color for Gliese 900 b, which the researchers interpret as a sign of low gravity for T-dwarfs. Low gravity is often seen as an indicator of a young age and a low mass.[15]
| Companion (in order from star) |
Mass | Projected separation (AU) |
Orbital period (106 years) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 10.5 MJ | 12,000 | 1.27[18] | – | – |
See also
- Circumtriple planet, a category of planets to which Gliese 900 b belongs
- List of exoplanets discovered in 2024 - including Gliese 900 b
Notes
- Using the apparent magnitude and distance from Earth, Gliese 900's absolute magnitude can be calculated.
9.546+5−5*log(20.85) = 7.95. - Using the angular separation and the parallax (both in milliarcseconds), the physical separation (in AU) can be obtained.
444/48.17 = 9.217 AU. - Out of objects with a planetary mass (<13 MJ). Exoplanet databases list a few brown dwarfs at larger separations.