Gliese 900 (GJ 900,BD+00 5017) is a triple star system, located 68light-years from Earth in the constellationPisces. It is made up of threemain sequence stars: one is aK-type star, the two others areM-dwarf stars. The two M-dwarfs form abinary 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 thenaked eye. A widely separated planet has been detected around the system.[7]
The system is young, about 200 million years old, and is a likely member (99.7% probability) of the nearbymoving groupCarina-Near.[9] It is a source ofX-ray emission, with an observed flux of9.13×102 mW M-2, and is also a source ofultraviolet emission.[7] The emission of X-rays is typical of young stars, and classifies it as one.[8] The TESS light curve identifiesstellar flares on this star.[7]
Gliese 900 B and C form an inner pair (named Gliese 900 BC) with anorbital period of around 36 years.[6] Gliese 900 BC and Gliese 900 A orbit the system'scenter of mass with a period of 80 years.[2][7] As of November 2004,[update] B was separated from A by 751milliarcseconds and C was separated from A by 708mas. This separation changes over time.[2] It was identified as a multiple star system in 2002 by Eduardo L. Martín, usingadaptive optics-corrected images at the 8.2 mSubaru Telescope. When first observed, the A–B and A–C separations were of 0.51 and 0.76 arcsecs respectively.[8] A further study by Malogolovetset al. (2007) identified this system as a hierarchical triple.[2]
Malogolovets et al. (2007) reported two other objects in 2MASS images (potentiallylate red dwarfs) that would be the components D and E and make the system quintuple, being "very likely" to be bound to the system.[2] However, these faint stars haven't been confirmed as members of the GJ 900 system, and are likely not associated.[7]
Gliese 900 is located 68 light-years from Earth, based onparallax measurements by theGaia spacecraft.[4] The BP-RP spectra suggest a distance of 67.7 ly.[4] Thespace velocity components of this system areU =−28.7,V =−15 andW =0.2.[10] Gliese 900 is part of thethin disk population of theMilky Way.[10][2] It was once classified as part of theIC 2602 supercluster.[8] A newer analysis usingkinematics from the Gaia spacecraft suggest that Gliese 900 has a 99.7% chance of being a member of theCarina-Near moving group and a 0.3% chance of being afield star, i.e. not associated to any star cluster or stellar association.[7]
As of 2024[update], Gliese 900 b has the largest observed separation of any known planet, and assuming a circular orbit, the longestorbital period.[14][15][d] The orbital period is estimated at 1.27[16] million years based on the projected separation. Due to the similar spectral type, orbital separation and age, CW2335+0142 has been compared toCOCONUTS-2b by the discovery team.[7]
Also in 2024, a study using data from theWide-field Infrared Survey Explorer found a red W2-W3 color, which the researchers interpret as a sign of lowgravity for T-dwarfs. Low gravity is often seen as an indicator of a young age and a low mass.[13]
