Tau Ceti, Latinized from τ Ceti, is a single star in the constellation Cetus that is spectrally similar to the Sun, although it has only about 78% of the Sun's mass. At a distance of just under 12 light-years from the Solar System, it is a relatively nearby star and the closest solitary G-class star. The star appears stable, with little stellar variation, and is metal-deficient relative to the Sun.
Proxima Centauri is the nearest star to Earth after the Sun, located 4.25 light-years away in the southern constellation of Centaurus. This object was discovered in 1915 by Robert Innes. It is a small, low-mass star, too faint to be seen with the naked eye, with an apparent magnitude of 11.13. Its Latin name means the 'nearest [star] of Centaurus'. Proxima Centauri is a member of the Alpha Centauri star system, being identified as component Alpha Centauri C, and is 2.18° to the southwest of the Alpha Centauri AB pair. It is currently 12,950 AU (0.2 ly) from AB, which it orbits with a period of about 550,000 years.
In astronomy and astrobiology, the habitable zone (HZ), or more precisely the circumstellar habitable zone (CHZ), is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure. The bounds of the HZ are based on Earth's position in the Solar System and the amount of radiant energy it receives from the Sun. Due to the importance of liquid water to Earth's biosphere, the nature of the HZ and the objects within it may be instrumental in determining the scope and distribution of planets capable of supporting Earth-like extraterrestrial life and intelligence.
Planetary habitability is the measure of a planet's or a natural satellite's potential to develop and maintain an environment hospitable to life. Life may be generated directly on a planet or satellite endogenously. Research suggests that life may also be transferred from one body to another, through a hypothetical process known as panspermia. Environments do not need to contain life to be considered habitable nor are accepted habitable zones (HZ) the only areas in which life might arise.
An Earth analog, also called an Earth twin or second Earth, is a planet or moon with environmental conditions similar to those found on Earth. The term Earth-like planet is also used, but this term may refer to any terrestrial planet.
Exoplanetary Circumstellar Environments and Disk Explorer(EXCEDE) is a proposed space telescope for NASA's Explorer program to observe circumstellar protoplanetary and debris discs and study planet formation around nearby stars of spectral classes M to B. Had it been selected for development, it was proposed to launch in 2019.
Kepler-62f is a super-Earth exoplanet orbiting within the habitable zone of the star Kepler-62, the outermost of five such planets discovered around the star by NASA's Kepler space telescope. It is located about 982 light-years from Earth in the constellation of Lyra.
The theorized habitability of red dwarf systems is determined by a large number of factors. Modern evidence suggests that planets in red dwarf systems are unlikely to be habitable, due to high probability of tidal locking, likely lack of atmospheres, and the high stellar variation many such planets would experience. However, the sheer number and longevity of red dwarfs could likely provide ample opportunity to realize any small possibility of habitability.
Kepler-442b is a confirmed near-Earth-sized exoplanet, likely rocky, orbiting within the habitable zone of the K-type main-sequence star Kepler-442, about 1,196 light-years (367 pc) from Earth in the constellation of Lyra.
Victoria Suzanne Meadows is a Professor with the Astronomy Department and Director of the Astrobiology Program at the University of Washington. She is also the Principal Investigator for the NASA Astrobiology Institute's Virtual Planetary Laboratory Lead Team and the chair of the NAI Focus Group on Habitability and Astronomical Biosignatures (HAB). The research direction of the team is to create computer models that can be used to understand planet formation, stability and orbital evolution, and to simulate the environment and spectra of planets that can potentially be habitable.
The Virtual Planetary Laboratory (VPL) is a virtual institute based at the University of Washington that studies how to detect exoplanetary habitability and their potential biosignatures. First formed in 2001, the VPL is part of the NASA Astrobiology Institute (NAI) and connects more than fifty researchers at twenty institutions together in an interdisciplinary effort. VPL is also part of the Nexus for Exoplanet System Science (NExSS) network, with principal investigator Victoria Meadows leading the NExSS VPL team.
Stephen Kane is a full professor of astronomy and planetary astrophysics at the University of California, Riverside who specializes in exoplanetary science. His work covers a broad range of exoplanet detection methods, including the microlensing, transit, radial velocity, and imaging techniques. He is a leading expert on the topic of planetary habitability and the habitable zone of planetary systems. He has published hundreds of peer reviewed scientific papers and has discovered/co-discovered several hundred planets orbiting other stars. He is a prolific advocate of interdisciplinarity science and studying Venus as an exoplanet analog.
Proxima Centauri b is an exoplanet orbiting within the habitable zone of the red dwarf star Proxima Centauri in the constellation Centaurus. It can also be referred to as Proxima b, or Alpha Centauri Cb. The host star is the closest star to the Sun, at a distance of about 4.2 light-years from Earth, and is part of the larger triple star system Alpha Centauri. Proxima b and Proxima d, along with the currently disputed Proxima c, are the closest known exoplanets to the Solar System.
The Habitable Exoplanet Observatory (HabEx) is a space telescope concept that would be optimized to search for and image Earth-size habitable exoplanets in the habitable zones of their stars, where liquid water can exist. HabEx would aim to understand how common terrestrial worlds beyond the Solar System may be and determine the range of their characteristics. It would be an optical, UV and infrared telescope that would also use spectrographs to study planetary atmospheres and eclipse starlight with either an internal coronagraph or an external starshade.
Antígona Segura Peralta is a Mexican physicist and astrobiologist. Since 2006, she has been a researcher at the Institute of Nuclear Sciences of the National Autonomous University of Mexico (UNAM) and collaborator at the NASA Astrobiology Institute. As a feminist she actively advocates for the inclusion of women in the exact sciences, mathematics, and engineering. Segura has participated in several activities in and outside UNAM defending women's rights; she was awarded with the 2021 Hermila Galindo medal by the Congress of Mexico City.
Kepler-1649c is an Earth-sized exoplanet, likely rocky, orbiting within the habitable zone of the red dwarf star Kepler-1649, the outermost planet of the planetary system discovered by Kepler’s space telescope. It is located about 301 light-years (92 pc) away from Earth, in the constellation of Cygnus.
The Planetary Habitability Laboratory (PHL) is a research remote laboratory intended to study the habitability of the Solar System and other stellar systems, specifically, potentially habitable exoplanets. The PHL is managed by the University of Puerto Rico at Arecibo with the collaboration of international scientists from different organizations including the SETI Institute and NASA. The Laboratory is directed by astrobiologist Professor Abel Méndez. PHL is especially known for its Habitable Exoplanets Catalog, one of the most comprehensive catalogs on exoplanetary habitability.
BLC1 was a candidate SETI radio signal detected and observed during April and May 2019, and first reported on 18 December 2020, spatially coincident with the direction of the Solar System's closest star, Proxima Centauri.
Habitability of yellow dwarf systems defines the suitability for life of exoplanets belonging to yellow dwarf stars. These systems are the object of study among the scientific community because they are considered the most suitable for harboring living organisms, together with those belonging to K-type stars.
