Discovery [1] | |
---|---|
Discovered by | L. Delrez et al. |
Discovery date | 2015 |
Transit | |
Designations | |
Tylos [2] | |
Orbital characteristics [3] | |
0.02596+0.00043 −0.00063 AU | |
Eccentricity | <0.0032 |
1.27492504(15) d | |
Inclination | 88.49°±0.16° |
10°±10° | |
Star | WASP-121 |
Physical characteristics [3] | |
1.753±0.036 RJ | |
Mass | 1.157±0.070 MJ |
Mean density | 0.266+0.024 −0.022 g/cm3 |
9.33+0.71 −0.67 m/s2 (0.95 g) | |
Temperature | 2602±53 K (2,329 °C; 4,224 °F) [4] |
WASP-121b, formally named Tylos, [2] is an exoplanet orbiting the star WASP-121. [5] [6] WASP-121b is the first exoplanet found to contain water in an extrasolar planetary stratosphere (i.e., an atmospheric layer in which temperatures increase as the altitude increases). [5] [6] WASP-121b is in the constellation Puppis, [7] and is about 858 light-years from Earth. [8] [5] [9]
In August 2022, this planet and its host star were included among 20 systems to be named by the third NameExoWorlds project. [10] The approved names, proposed by a team from Bahrain, were announced in June 2023. WASP-121b is named Tylos after the ancient Greek name for Bahrain, and its host star is named Dilmun after the ancient civilization. [2]
WASP-121b is a hot Jupiter exoplanet with a mass about 1.16 times that of Jupiter and a radius about 1.75 times that of Jupiter. The exoplanet orbits WASP-121, its host star, every 1.27 days. [3]
In 2019 a work by Hellard et al. discussed the possibility of measuring the Love number of transiting hot Jupiters using HST/STIS. A tentative measurement of for WASP-121b was published in the same work. [11] [12]
The planetary orbit is inclined to the equatorial plane of the star by 8.1°. [13]
A spectral survey in 2015 attributed 2,500 °C (4,530 °F), hot [5] stratosphere absorption bands to water molecules, titanium(II) oxide (TiO) and vanadium(II) oxide (VO). [14] Neutral iron was also detected in the stratosphere of WASP-121b in 2020, [15] [16] along with neutral chromium and vanadium. [17] The detection claims of titanium(II) oxide (TiO) and vanadium(II) oxide (VO) have since been disproved. [6] [18] [19] [20]
Reanalysis of aggregated spectral data was published in June 2020. Neutral magnesium, calcium, vanadium, chromium, iron, and nickel, along with ionized sodium atoms, were detected. The low quality of available data preclude a positive identification of any molecular species, including water. The atmosphere appears to be significantly out of chemical equilibrium and possibly escaping. [21] The strong atmospheric flows beyond the Roche lobe, indicating ongoing atmosphere loss, were confirmed in late 2020. [13]
In 2021, the planetary atmosphere turned out to be slightly more blue and less absorbing, which may be an indication of planetary weather patterns. [22] By mid-2021, the presence of ions of iron, chromium, vanadium and calcium in the planetary atmosphere was confirmed. [23] In 2022, barium was also detected. [24] By 2022, an absence of titanium in the planetary atmosphere was confirmed and attributed to the nightside condensation of highly refractory titanium dioxide. [25]
Observations by the Hubble Space Telescope from 2016-2019, published in 2024, confirm variability in the atmosphere of WASP-121b. [26] [27]
The sodium detected via absorption spectroscopy around WASP-121b [21] is consistent with an extrasolar gas torus, possibly fueled by a hidden exo-Io. [28]
WASP-6b, also named Boinayel, is an exoplanet approximately 650 light years away in the constellation Aquarius. It was discovered in 2008, by the WASP survey, by astronomical transit across its parent star WASP-6. This planet orbits at only 4% of the Earth-Sun distance. The planet has a mass half that of Jupiter, but its insolation has forced a thermal expansion of its radius to greater than that of Jupiter. Thus, this planet is an inflated hot Jupiter. Starspots on the host star WASP-6 helped to refine the measurements of the mass and the radius of the planet.
WASP-33b is an extrasolar planet orbiting the star HD 15082. It was the first planet discovered to orbit a Delta Scuti variable star. With a semimajor axis of 0.026 AU and a mass likely greater than Jupiter's, it belongs to the hot Jupiter class of planets.
WASP-43b, formally named Astrolábos, is a transiting planet in orbit around the young, active, and low-mass star WASP-43 in the constellation Sextans. The planet is a hot Jupiter with a mass twice that of Jupiter, but with a roughly equal radius. WASP-43b was flagged as a candidate by the SuperWASP program, before they conducted follow-ups using instruments at La Silla Observatory in Chile, which confirmed its existence and provided orbital and physical characteristics. The planet's discovery was published on April 14, 2011.
WASP-121, also known as CD-38 3220 and formally named Dilmun, is a magnitude 10.4 star located approximately 858 light-years away in the constellation Puppis. WASP-121 has a mass and radius similar to the Sun's. It hosts one known exoplanet.
WASP-31b is a low-density (puffy) "hot Jupiter" extrasolar planet orbiting the metal-poor dwarf star WASP-31. The exoplanet was discovered in 2010 by the WASP project. WASP-31b is in the constellation of Crater, and is about 1305 light-years from Earth.
WASP-49 is a binary star system about 636 light-years away in the constellation Lepus. The two stars are separated by 443 AU. The primary is a G-type main-sequence star, with a surface temperature of 5,600 K. WASP-49 is depleted of heavy elements relative to the Sun. It has a metallicity Fe/H index of –0.23, meaning it has 59% the iron level of the Sun.
WASP-76b is an exoplanet classified as a Hot Jupiter. It is located in the constellation Pisces and orbits its host star, WASP-76, at a distance of approximately 0.033 AU. Its orbital period is approximately 1.8 days, and its mass is about 0.92 times that of Jupiter. The discovery of WASP-76b took place on October 21, 2013; as of 2022, it is the only known planet in the WASP-76 system. The equilibrium temperature of WASP-76b is estimated to be around 2,190 K, However, the measured daytime temperature is higher, reaching approximately 2,500 ± 200 K.
WASP-52 is a K-type main-sequence star about 570 light-years away. It is older than the Sun at 10.7+1.9
−4.5 billion years, but it has a similar fraction of heavy elements. The star has prominent starspot activity, with 3% to 14% of the stellar surface covered by areas 575±150 K cooler than the rest of the photosphere.
WASP-69, also named Wouri, is a K-type main-sequence star 164 light-years away. Its surface temperature is 4782±15 K. WASP-69 is slightly enriched in heavy elements compared to the Sun, with a metallicity Fe/H index of 0.10±0.01, and is much younger than the Sun at 2 billion years. The data regarding starspot activity of WASP-69 are inconclusive, but spot coverage of the photosphere may be very high.
WASP-75 is a F-type main-sequence star about 980 light-years away. The star is much younger than the Sun at approximately 2.9±0.2 billion years. WASP-75 is similar to the Sun in its concentration of heavy elements.
WASP-88 is a F-type main-sequence star. Its surface temperature is 6450±61 K. WASP-88 is similar to the Sun in its concentration of heavy elements, with a metallicity Fe/H index of 0.03±0.04, and is younger at an age of 3.0±1.3 billion years.
WASP-80 is a K-type main-sequence star about 162 light-years away from Earth. The star's age is much younger than the Sun's at 1.352±0.222 billion years. WASP-80 could be similar to the Sun in concentration of heavy elements, although this measurement is highly uncertain.
WASP-103 is an F-type main-sequence star located 1,800 ± 100 light-years away in the constellation Hercules. Its surface temperature is 6,110±160 kelvins (K). The star's concentration of heavy elements is similar to that of the Sun. WASP-103 is slightly younger than the Sun at 4±1 billion years. The chromospheric activity of the star is elevated due to interaction with the giant planet on a close-in orbit.