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Lalande 21185 is a star in the south of Ursa Major. It is the apparent brightest red dwarf in the northern hemisphere. Despite this, and being relatively close by, it is very dim, being only magnitude 7.5 in visible light and thus too faint to be seen with the unaided eye. The star is visible through a small telescope or binoculars.
Ross 128 is a red dwarf in the equatorial zodiac constellation of Virgo, near β Virginis. The apparent magnitude of Ross 128 is 11.13, which is too faint to be seen with the unaided eye. Based upon parallax measurements, the distance of this star from Earth is 11.007 light-years, making it the twelfth closest stellar system to the Solar System. It was first cataloged in 1926 by American astronomer Frank Elmore Ross.
Luyten's Star (GJ 273) is a red dwarf in the constellation Canis Minor located at a distance of approximately 12.35 light-years from the Sun. It has a visual magnitude of 9.9, making it too faint to be viewed with the unaided eye. It is named after Willem Jacob Luyten, who, in collaboration with Edwin G. Ebbighausen, first determined its high proper motion in 1935. The star has two confirmed planets and two candidate planets, of which Luyten b is in the circumstellar habitable zone.
82 G. Eridani is a star 19.7 light-years away from Earth in the constellation Eridanus. It is a main-sequence star with a stellar classification of G6 V, and it hosts a system of at least three planets and a dust disk.
Solar-type star, solar analogs, and solar twins are stars that are particularly similar to the Sun. The stellar classification is a hierarchy with solar twin being most like the Sun followed by solar analog and then solar-type. Observations of these stars are important for understanding better the properties of the Sun in relation to other stars and the habitability of planets.
Gliese 581 is a red dwarf star of spectral type M3V at the center of the Gliese 581 planetary system, about 20.5 light years away from Earth in the Libra constellation. Its estimated mass is about a third of that of the Sun, and it is the 101st closest known star system to the Sun. Gliese 581 is one of the oldest, least active M dwarfs known. Its low stellar activity improves the likelihood of its planets retaining significant atmospheres, and lessens the sterilizing impact of stellar flares.
Gliese 581c is a planet orbiting within the Gliese 581 system. It is the second planet discovered in the system and the third in order from the star. With a mass at least 5.5 times that of the Earth, it is classified as a super-Earth.
Gliese 581d was a candidate extrasolar planet orbiting within the Gliese 581 system, approximately 20.4 light-years away in the Libra constellation. It was the third planet claimed in the system and the fourth or fifth in order from the star. Multiple subsequent studies found that the planetary signal in fact originates from stellar activity, and thus the planet does not exist.
Gliese 832 is a red dwarf of spectral type M2V in the southern constellation Grus. The apparent visual magnitude of 8.66 means that it is too faint to be seen with the naked eye. It is located relatively close to the Sun, at a distance of 16.2 light years and has a high proper motion of 818.16 milliarcseconds per year. Gliese 832 has just under half the mass and radius of the Sun. Its estimated rotation period is a relatively leisurely 46 days. The star is roughly 6 billion years old.
HD 189733 b is an exoplanet approximately 64.5 light-years (19.8 pc) away from the Solar System in the constellation of Vulpecula. Astronomers in France discovered the planet orbiting the star HD 189733 on October 5, 2005, by observing its transit across the star's face. With a mass 16.2% higher than that of Jupiter and a radius 13.8% greater, HD 189733 b orbits its host star once every 2.2 days at an orbital speed of 152.5 kilometers per second, making it a hot Jupiter with poor prospects for extraterrestrial life.
HD 221287, named Poerava, is a star in the southern constellation of Tucana. It has a yellow-white hue but is too faint to be viewed with the naked eye, having an apparent visual magnitude of 7.82. This object is located at a distance of 183 light years from the Sun, as determined from its parallax. It is drifting closer with a radial velocity of −22 km/s.
HD 40307 is an orange (K-type) main-sequence star located approximately 42 light-years away in the constellation of Pictor, taking its primary name from its Henry Draper Catalogue designation. It is calculated to be slightly less massive than the Sun. The star has six known planets, three discovered in 2008 and three more in 2012. One of them, HD 40307 g, is a potential super-Earth in the habitable zone, with an orbital period of about 200 days. This object might be capable of supporting liquid water on its surface, although much more information must be acquired before its habitability can be assessed.
HD 29587 is a Sun-like star with a candidate brown dwarf companion in the northern constellation of Perseus. It has an apparent visual magnitude of 7.29, which means it is too faint to be viewed with the naked eye. Based upon an annual parallax shift of 36.3 mas, it is located 89.8 light years away. The star is moving away from the Earth with a heliocentric radial velocity of +113 km/s, having come to within 55.8 ly some 148,000 years ago. It is a hyper-velocity halo star moving at a rate of 170 km/s relative to the local standard of rest.
An exoplanet is a planet located outside the Solar System. The first evidence of an exoplanet was noted as early as 1917, but was not recognized as such until 2016; no planet discovery has yet come from that evidence. What turned out to be the first detection of an exoplanet was published among a list of possible candidates in 1988, though not confirmed until 2003. The first confirmed detection came in 1992, with the discovery of terrestrial-mass planets orbiting the pulsar PSR B1257+12. The first confirmation of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods, such as the transit method and the radial-velocity method. As of 1 March 2023, there are 5,332 confirmed exoplanets in 3,931 planetary systems, with 855 systems having more than one planet. This is a list of the most notable discoveries.
HD 40307 f is an extrasolar planet orbiting the star HD 40307. It is located 42 light-years away in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the European Southern Observatory's HARPS apparatus by a team of astronomers led by Mikko Tuomi at the University of Hertfordshire and Guillem Anglada-Escude of the University of Göttingen, Germany. The existence of planet was confirmed in 2015.
HD 222155 is a star in the northern constellation of Andromeda. It is a yellow star that can be viewed with binoculars or a small telescope, but is too faint to be seen with the naked eye at an apparent visual magnitude of 7.1. The imaging survey in 2017 did not detect any stellar companions to HD 222155.
HD 164595 is a G-type star located in the constellation of Hercules, 28.28 parsecs from Earth that is notably similar to the Sun. With an apparent magnitude of 7.075, the star can be found with binoculars or a small telescope in the constellation Hercules.
References
- 1 2 3 4 5 6 "HD 164595 b Confirmed Planet Overview Page". NASA . Retrieved 31 August 2016.
- ↑ Courcol, Bastien; Bouchy, François; Pepe, Francesco; Santerne, Alexandre; Delfosse, Xavier; Arnold, Luc; Astudillo-Defru, Nicola; Boisse, Isabelle; Bonfils, Xavier (1 September 2015). "The SOPHIE search for northern extrasolar planets". Astronomy & Astrophysics. 581: A38. arXiv: 1506.07144 . Bibcode:2015A&A...581A..38C. doi:10.1051/0004-6361/201526329. ISSN 0004-6361. S2CID 119181352.
- 1 2 Plait, Phil (31 August 2016). "No, We Almost Certainly Did Not Detect an Alien Signal". Slate.
- ↑ Moody, Oliver (31 August 2016). "PAYWALL - Title => Signal from the stars could be ET phoning Earth". The Times . Retrieved 31 August 2016.
- ↑ Gilster, Paul (27 August 2016). "An Interesting SETI Candidate in Hercules". Centauri Dreams. Retrieved 29 August 2016.
- 1 2 3 Griffiths, James (30 August 2016). "Hear me now? 'Strong signal' from sun-like star sparks alien speculation". CNN . Retrieved 30 August 2016.
- ↑ SETI observations on the RATAN-600 telescope in 2015 and detection of a strong signal in the direction of HD 164595 Bursov N., Filippova L., Filippov V., Gindilis L., Maccone C. et al. 2016 | in " IAA SETI Permanent Committee", Guadalajara, Mexico.
- ↑ Staff (29 August 2016). "Mystery radio signal may be from distant star system – or a military transmitter". KurzweilAI . Retrieved 31 August 2016.
- ↑ Korpela, Eric (29 August 2016). "Uninteresting from a SETI point of view".
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