Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Cygnus [1] |
Right ascension | 20h 49m 27.44052s [2] |
Declination | +33° 36′ 50.9686″ [2] |
Apparent magnitude (V) | 17.8 (estimate) [3] |
Characteristics | |
Evolutionary stage | Red dwarf |
Spectral type | M6.5±0.5 [4] |
Apparent magnitude (B) | 19 [5] |
Apparent magnitude (R) | 16.4 [5] |
Apparent magnitude (G) | 15.379 [2] |
Apparent magnitude (J) | 11.5 [6] |
Apparent magnitude (H) | 10.867±0.021 [5] |
Apparent magnitude (K) | 10.54 [6] |
Astrometry | |
Proper motion (μ) | RA: –207.809 mas/yr [2] Dec.: –412.215 mas/yr [2] |
Parallax (π) | 59.7005 ± 0.0434 mas [2] |
Distance | 54.63 ± 0.04 ly (16.75 ± 0.01 pc) [2] |
Details [4] | |
Mass | 0.1009±0.0024 M☉ |
Radius | 0.123±0.0022 R☉ |
Luminosity | 0.000835±0.000019 L☉ |
Surface gravity (log g) | 5.265±0.014 cgs |
Temperature | 2800±29 K |
Metallicity [Fe/H] | 0.07±0.1 dex |
Rotation | 1.34±0.14 d |
Rotational velocity (v sin i) | 4.8±0.5 km/s |
Age | 6.6+1.8 −2.4 Gyr |
Other designations | |
Database references | |
SIMBAD | data |
Exoplanet Archive | data |
SPECULOOS-3, also known as LSPM J2049+3336, is a red dwarf star (spectral type M6.5) located 54.6 light-years from Earth [4] in the constellation Cygnus. It is one of the smallest known stars, and is much cooler, dimmer and smaller than the Sun, having 0.1 times the mass, 0.08% the Sun's luminosity, and an effective temperature of 2,800 K (2,530 °C), which is less than half of the Sun's temperature (5,772 K). [4] It is orbited by one known exoplanet, and is the second ultra-cool dwarf discovered to have a planetary system, after TRAPPIST-1. [7] [8]
The age of SPECULOOS-3 is constrained at 6.6 billion years, 44% older than the Solar System, with significant margins of error. A bayesian analysis of the star derived a mass of 0.101 M☉, an effective temperature of 2,800 K (2,530 °C; 4,580 °F) and a luminosity of 8.35×10−6 L☉. These characteristics classify SPECULOOS-3 as an ultracool dwarf, which are stars at the end of the main sequence, with low temperatures, low luminosites and sizes similar to Jupiter. It is spinning at a rotational velocity of 4.8 km/s and has a projected rotational period of 1.34 days. [4]
The stellar radius, computed using the Stefan–Boltzmann law, is 0.134 R☉ (93,000 kilometres). [4] This makes SPECULOOS-3 the second-smallest star known to host a transiting planet, just marginally larger than TRAPPIST-1, [4] and its size is similar to that of Jupiter. [9] Its apparent magnitude is estimated at 17.8, [3] which is too faint to be seen by the naked eye.
It was first discovered in 2005 as part of the LSPM-North catalog, whose objective was to map stars in the northern celestial hemisphere with proper motions larger than 0.15" per year and apparent magnitudes smaller than 21m. [3] Its trignometric parallax was first measured in 2014 at 67.5±1.7 mas , translating into a distance of 14.8 parsecs (48.27 ly). [6] Gaia Data Release 3 (2023) published a parallax of 59.7 milliarcseconds, translating into a distance of 16.75 parsecs (54.6 ly). [2] This make this star relatively close to Earth. [10]
Red dwarf stars such as SPECULOOS-3 are the most numerous type of stars, making up 70% of all stars in the Milky Way galaxy. They are expected to live 10 times more than the Sun, with lifespans longer than 100 billion years. [10]
SPECULOOS-3 hosts one exoplanet, discovered in 2024 via the transit method. [11] Named SPECULOOS-3 b, it is an Earth-sized exoplanet that has a radius similar to that of Earth, equivalent to 0.98 Earth radii. [4] It takes only about 17 hours to complete an orbit around SPECULOOS-3, and, because of that proximity, it receives very high levels of radiation and is likely tidally locked, meaning that one side of the planet always faces its host star. [9] Its discovery was made using the SPECULOOS project, and was announced on 15 May 2024 in the academic journal Nature Astronomy. [12]
The mass of SPECULOOS-3 b has been not measured, [4] but it has been estimated by NASA's Eyes on Exoplanets at 0.894 ME. [13] Its equilibrium temperature is about 553 K (280 °C; 536 °F), meaning that its dayside is likely formed by solid rock. [4] The planet is an optimal target for characterization with the James Webb Space Telescope, giving more information about the planet's mineralogy [12] and the possibility of hosting an atmosphere. [14]
Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | — | 0.007330(55) | 0.71912603(57) | — | 89.44±0.39 ° | 0.977±0.022 R🜨 |
HD 114386 is a star with a pair of orbiting exoplanets in the southern constellation of Centaurus. It has an apparent visual magnitude of 8.73, which means it cannot be viewed with the naked eye but can be seen with a telescope or good binoculars. Based on parallax measurements, the system is located at a distance of 91 light years from the Sun. It is receding with a radial velocity of 33.4 km/s. The star shows a high proper motion, traversing the celestial sphere at an angular rate of 0.318 arcsec yr−1.
HD 114762 is a triple star system approximately 125 light-years (38.2 pc) away in the constellation Coma Berenices. It consists of a yellow-white F-type main-sequence star (HD 114762 A) and two red dwarf companions (HD 114762 Ab & HD 114762 B) approximately 0.36 & 130 AU distant. Both are low-metal subdwarfs. Planets around such metal-poor stars are rare. A telescope or strong binoculars are needed to view the primary. HD 114762 had been used by scientists as a "standard star", one whose radial velocity is well established, but with the discovery of the spectroscopic companion HD 114762 Ab its usefulness as a standard has been called into question.
HD 162020 is a star in the southern constellation of Scorpius with a likely red dwarf companion. It has an apparent visual magnitude of 9.10, which is too faint to be visible to the naked eye. The distance to this system is 102 light-years based on stellar parallax. It is drifting closer to the Sun with a radial velocity of −27 km/s, and is predicted to come to within ~18 light-years in 1.1 million years.
Gliese 179 is a small red dwarf star with an exoplanetary companion in the equatorial constellation of Orion. It is much too faint to be visible to the naked eye with an apparent visual magnitude of 11.94. The system is located at a distance of 40.5 light-years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of –9 km/s. It is a high proper motion star, traversing the celestial sphere at an angular rate of 0.370″·yr−1.
Kepler-70, also known as KIC 5807616 and KOI-55, is a star about 3,600 light-years away in the constellation Cygnus, with an apparent visual magnitude of 14.87. This is too faint to be seen with the naked eye; viewing it requires a telescope with an aperture of 40 cm (20 in) or more. A subdwarf B star, Kepler-70 passed through the red giant stage some 18.4 million years ago. In its present-day state, it is fusing helium in its core. Once it runs out of helium it will contract to form a white dwarf. It has a relatively small radius of about 0.2 times the Sun's radius; white dwarfs are generally much smaller. The star may be host to a planetary system with two planets, although later research indicates that this is not in fact the case.
HD 109271 is a wide binary star system in the constellation of Virgo. The brighter member of the binary has a pair of orbiting exoplanets. With an apparent visual magnitude of 8.05, it cannot be seen with the naked eye. Parallax measurements made by Gaia put the star at a distance of 181 light-years away from the Sun, but it is drifting closer with a radial velocity of −5 km/s. The system shows a high proper motion, traversing the celestial sphere at an angular rate of 0.232 arcsec yr−1.
Gliese 393, or GJ 393, is a single star with an orbiting exoplanet companion in the equatorial constellation of Sextans, positioned about 1.5° to the NNW of Beta Sextantis. At an apparent visual magnitude of 9.65, it is much too faint to be seen with the unaided eye. This star is located at a distance of 22.9 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +8.3 km/s. It has a large proper motion, traversing the celestial sphere at the rate of 0.950″ per year. The net velocity of this star relative to the Sun is 32.9 km/s. It shares a similar space motion as members of the AB Doradus moving group, but is considered a random interloper.
Kepler-444 is a triple star system, estimated to be 11.2 billion years old, approximately 119 light-years (36 pc) away from Earth in the constellation Lyra. On 27 January 2015, the Kepler spacecraft is reported to have confirmed the detection of five sub-Earth-sized rocky exoplanets orbiting the main star. The star is a K-type main sequence star. All of the planets are far too close to their star to harbour life forms.
SPECULOOS (Search for habitable Planets EClipsing ULtra-cOOl Stars) is a project consisting of SPECULOOS Southern Observatory (SSO) at the Paranal Observatory in Chile and SPECULOOS Northern Observatory (SNO) at the Teide Observatory in Tenerife.
TRAPPIST-1d is a small exoplanet, which orbits on the inner edge of the habitable zone of the ultracool dwarf star TRAPPIST-1, located 40.7 light-years away from Earth in the constellation of Aquarius. The exoplanet was found by using the transit method. The first signs of the planet were announced in 2016, but it was not until the following years that more information concerning the probable nature of the planet was obtained. TRAPPIST-1d is the second-least massive planet of the system and is likely to have a compact hydrogen-poor atmosphere similar to Venus, Earth, or Mars. It receives just 4.3% more sunlight than Earth, placing it on the inner edge of the habitable zone. It has about <5% of its mass as a volatile layer, which could consist of atmosphere, oceans, and/or ice layers. A 2018 study by the University of Washington concluded that TRAPPIST-1d might be a Venus-like exoplanet with an uninhabitable atmosphere. The planet is an eyeball planet candidate.
TRAPPIST-1c, also designated as 2MASS J23062928-0502285 c, is a mainly rocky exoplanet orbiting around the ultracool dwarf star TRAPPIST-1, located 40.7 light-years (12.5 parsecs) away from Earth in the constellation Aquarius. It is the third most massive and third largest planet of the system, with about 131% the mass and 110% the radius of Earth. Its density indicates a primarily rocky composition, and observations by the James Webb Space Telescope announced in 2023 suggests against a thick CO2 atmosphere, however this does not exclude a thick abiotic oxygen-dominated atmosphere as is hypothesized to be common around red dwarf stars.
TRAPPIST-1f, also designated as 2MASS J23062928-0502285 f, is an exoplanet, likely rocky, orbiting within the habitable zone around the ultracool dwarf star TRAPPIST-1, located 40.7 light-years away from Earth in the constellation of Aquarius. The exoplanet was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured.
TRAPPIST-1e, also designated as 2MASS J23062928-0502285 e, is a rocky, close-to-Earth-sized exoplanet orbiting within the habitable zone around the ultracool dwarf star TRAPPIST-1, located 40.7 light-years away from Earth in the constellation of Aquarius. Astronomers used the transit method to find the exoplanet, a method that measures the dimming of a star when a planet crosses in front of it.
HD 21749 is an orange main-sequence star in the constellation Reticulum. It has an apparent visual magnitude of 8.143, which means it is too dim to be seen with the naked eye. From parallax measurements by the Gaia spacecraft, it is located 53 ly (16 pc) from Earth.
LSPM J0207+3331 is a cold and old white dwarf that hosts a circumstellar disk, located 145 light-years from Earth. It was discovered in October 2018 by a volunteer participating in the Backyard Worlds citizen science project. Until 2021 it was the oldest and coldest white dwarf known to host a disk. The white dwarf WD 2317+1830 with a detected disk is at least twice as old and around 2,000 K colder.
LTT 1445 is a triple M-dwarf system 22.4 light-years distant in the constellation Eridanus. The primary LTT 1445 A hosts two exoplanets—one discovered in 2019 that transits the star every 5.36 days, and another found in 2021 that transits the star every 3.12 days, close to a 12:7 resonance. As of October 2022 it is the second closest transiting exoplanet system discovered, with the closest being HD 219134 bc.
K2-315b is an exoplanet located 185.3 light years away from Earth in the southern zodiac constellation Libra. It orbits the red dwarf K2-315.
K2-296b is a potentially habitable planet discovered by Heller et al. in 2019, orbiting the M-dwarf star EPIC 201238110.
LP 890-9, also known as SPECULOOS-2 or TOI-4306, is a high proper motion red dwarf star located 105 light-years (32 pc) away from the Solar System in the constellation of Eridanus. The star has 12% the mass and 15% the radius of the Sun, and a temperature of 2,871 K. It is extremely faint and, with an apparent magnitude of 18, is the faintest star with exoplanets discovered by the Transiting Exoplanet Survey Satellite.
SPECULOOS-3 b is an Earth-sized exoplanet, orbiting the ultracool red dwarf star SPECULOOS-3. It is relatively close to Earth, at a distance of 55 light-years. SPECULOOS-3 b takes only about 17 hours to complete an orbit around SPECULOOS-3, and, because of that proximity, it receives very high levels of radiation and is tidally locked, meaning that one side of the planet always faces its host star. Its discovery was made using the SPECULOOS project, and announced in May 2024 in the academic journal Nature Astronomy.