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Mikko Tuomi
Mikko Tuomi is a Finnish astronomer from the University of Hertfordshire, most known for his contributions to the discovery of a number of exoplanets, among them the Proxima Centauri b which orbits the closest star to the Sun. Mikko Tuomi was the first to find indications of the existence of Proxima Centauri b in archival observation data. Other exoplanets to whose discovery or study Tuomi has contributed include HD 40307, HD 154857 c,The Anglo-Australian Planet Search. XXIII. Two New Jupiter Analogs Robert A. Wittenmyer, Jonathan Horner, C.G. Tinney, R.P. Butler, H.R.A. Jones, Mikko Tuomi, G.S. Salter, B.D. Carter, F. Elliott Koch, S.J. O'Toole, J. Bailey, D. Wright Kapteyn c, |
Espoo
Espoo (, ; sv, Esbo) is a city and municipality in the region of Uusimaa in the Republic of Finland. It is located on the northern shore of the Gulf of Finland, bordering the cities of Helsinki, Vantaa, Kirkkonummi, Vihti and Nurmijärvi while surrounding the enclaved town of Kauniainen. The city covers with a population of about 300 000 residents in 2022, making it the 2nd-most populous city in Finland. Espoo forms a major part of a substantially larger metropolitan area known as Greater Helsinki, home to over 1.5 million people in 2020. Espoo was first settled in the Prehistoric Era, with the first signs of human settlements going back as far as 8,000 years, but the population effectively disappeared in the early stages of the Iron Age. In the Early Middle Ages, the area was resettled by Tavastians and Southwestern Finns. After the Northern Crusades, Swedish settlers started migrating to the coastal areas of present-day Finland, and Espoo was established as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 154857
HD 154857 is a star with two exoplanetary companions in the southern constellation of Ara. It is too dim to be visible with the naked eye having an apparent visual magnitude of 7.25. The star is located at a distance of 207 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of +28 km/s. This is a G-type star with a stellar classification of G5IV-V. The absolute magnitude of this star is two magnitudes above the main sequence, which suggests that the star is evolving toward the subgiant stage. It is a metal-poor thin disk star approximately six billion years old and is chromopherically quiet although not in a Maunder Minimum state. The star is larger, more massive, and more luminous than the Sun. It is spinning with a projected rotational velocity of 1.4 km/s. Planetary system The discovery of one confirmed and one unconfirmed Jovian exoplanet was reported in 2004 and 2007 respectively. The for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Finnish Astronomers
Finnish may refer to: * Something or someone from, or related to Finland * Culture of Finland * Finnish people or Finns, the primary ethnic group in Finland * Finnish language, the national language of the Finnish people * Finnish cuisine See also * Finish (other) * Finland (other) * Suomi (other) * {{disambiguation Language and nationality disambiguation pages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exoplanetology
This page describes exoplanet orbital and physical parameters. Orbital parameters Most known extrasolar planet candidates have been discovered using indirect methods and therefore only some of their physical and orbital parameters can be determined. For example, out of the six independent parameters that define an orbit, the radial-velocity method can determine four: semi-major axis, eccentricity, longitude of periastron, and time of periastron. Two parameters remain unknown: inclination and longitude of the ascending node. Distance from star and orbital period There are exoplanets that are much closer to their parent star than any planet in the Solar System is to the Sun, and there are also exoplanets that are much further from their star. Mercury, the closest planet to the Sun at 0.4 astronomical units (AU), takes 88 days for an orbit, but the smallest known orbits of exoplanets have orbital periods of only a few hours, see Ultra-short period planet. The Kepler-11 sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proxima Centauri
Proxima Centauri is a small, low-mass star located away from the Sun in the southern constellation of Centaurus. Its Latin name means the 'nearest tarof Centaurus'. It was discovered in 1915 by Robert Innes and is the nearest-known star to the Sun. With a quiescent apparent magnitude of 11.13, it is too faint to be seen with the unaided eye. 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 from AB, which it orbits with a period of about 550,000 years. Proxima Centauri is a red dwarf star with a mass about 12.5% of the Sun's mass (), and average density about 33 times that of the Sun. Because of Proxima Centauri's proximity to Earth, its angular diameter can be measured directly. Its actual diameter is about one-seventh (14%) the diameter of the Sun. Although it has a very low average luminosity, Pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravitational Tugging
A gravity tractor is a theoretical spacecraft that would deflect another object in space, typically a potentially hazardous asteroid that might impact Earth, without physically contacting it, using only its gravitational field to transmit the required impulse. The gravitational force of a nearby space vehicle, though small, is able to alter the path of a much larger asteroid if the vehicle spends enough time close to it; all that is required is that the vehicle thrust in a consistent direction relative to the asteroid's path, and that neither the vehicle nor its expelled reaction mass come in direct contact with the asteroid. The tractor spacecraft could either hover near the object being deflected, or orbit it, directing its exhaust perpendicular to the plane of the orbit. The concept has two key advantages: namely that essentially nothing needs to be known about the mechanical composition and structure of the asteroid in advance; and that the relatively small amounts of force use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GJ667C
Gliese 667 (142 G. Scorpii) is a triple-star system in the constellation Scorpius lying at a distance of about from Earth. All three of the stars have masses smaller than the Sun. There is a 12th-magnitude star close to the other three, but it is not gravitationally bound to the system. To the naked eye, the system appears to be a single faint star of magnitude 5.89. The system has a relatively high proper motion, exceeding 1 second of arc per year. The two brightest stars in this system, GJ 667 A and GJ 667 B, are orbiting each other at an average angular separation of 1.81 arcseconds with a high eccentricity of 0.58. At the estimated distance of this system, this is equivalent to a physical separation of about 12.6 AU, or nearly 13 times the separation of the Earth from the Sun. Their eccentric orbit brings the pair as close as about 5 AU to each other, or as distant as 20 AU, corresponding to an eccentricity of 0.6.Based on a calculated eccentricity value ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Potentially Habitable Exoplanets
This is a list of potentially habitable exoplanets. The list is mostly based on estimates of habitability by the Habitable Exoplanets Catalog (HEC), and data from the NASA Exoplanet Archive. The HEC is maintained by the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo. There is also a speculative list being developed of superhabitable planets. Surface planetary habitability is thought to require orbiting at the right distance from the host star for liquid surface water to be present, in addition to various geophysical and geodynamical aspects, atmospheric density, radiation type and intensity, and the host star's plasma environment. List This is a list of exoplanets within the circumstellar habitable zone that are under 10 Earth masses and smaller than 2.5 Earth radii, and thus have a chance of being rocky. Note that inclusion on this list does not guarantee habitability, and in particular the larger planets are unlikely to have a rocky composition. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau Ceti
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 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. It can be seen with the unaided eye with an apparent magnitude of 3.5. As seen from Tau Ceti, the Sun would be in the northern hemisphere constellation Boötes with an apparent magnitude of about 2.6.From Tau Ceti the Sun would appear on the diametrically opposite side of the sky at the coordinates RA = , Dec = , which is located near Tau Boötis. The absolute magnitude of the Sun is 4.8, so, at a distance of , the Sun would have an apparent magnitude m = M_v + 5 \cdot (\log_ 3.64 - 1) = 2.6. Observations have detected more than ten times as much dust surrounding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gliese 581 G
Gliese 581g , unofficially known as Zarmina (or Zarmina's World), was a candidate exoplanet postulated to orbit within the Gliese 581 system, twenty light-years from Earth. It was discovered by the Lick–Carnegie Exoplanet Survey, and was the sixth planet claimed to orbit the star; however, its existence could not be confirmed by the European Southern Observatory (ESO) / High Accuracy Radial Velocity Planet Searcher (HARPS) survey team, and was ultimately refuted. It was thought to be near the middle of the habitable zone of its star, meaning it could sustain liquid water—a necessity for all known life—on its surface, if there are favorable atmospheric conditions on the planet. Gliese 581g was claimed to be detected by astronomers of the Lick–Carnegie Exoplanet Survey. The authors stated that data sets from both the High Resolution Echelle Spectrometer (HIRES) and HARPS were needed to sense the planet; however, the ESO/HARPS survey team could not confirm its existence. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gliese 221
Gliese 221 (GJ 221), also known as BD-06 1339, is a star with an exoplanetary companion in the equatorial constellation of Orion. It is too faint to be visible to the naked eye, having an apparent visual magnitude of 9.70 and an absolute magnitude of 8.15. Using parallax measurements, the distance to this system can be estimated as 66.2 light-years. It is receding from the Sun with a radial velocity of +23 km/s. This is a high proper motion star, traversing the celestial sphere at an angular rate of ·yr−1. This is a late K-type or early M-type main-sequence star with a stellar classification of K7V/M0V. It has 72% of the mass and 61% of the radius of the Sun. The star is roughly 4.4 billion years old and is depleted in heavy elements, containing just 46% of solar abundance of iron. It is an active star and the level of chromospheric activity has been found to vary significantly over time. The star is radiating 10% of the luminosity of the Sun from i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gliese 682 C
Gliese 682 or GJ 682 is a red dwarf. It is listed as the 49th-nearest known star to the Sun, being about 16 light years away from the Earth. Even though it is close by, it is dim with a magnitude of 10.95 and thus requires a telescope to be seen. It is located in the constellation of Scorpius, near the bright star Theta Scorpii. The star is in a crowded region of sky near the Galactic Center, and so appears to be near a number of deep-sky objects from the Solar System's perspective. The star is only 0.5 degrees from the much more distant globular cluster NGC 6388. Hypothetical planetary system Two candidate planets were detected orbiting Gliese 682 in 2014, one of which would be in the habitable zone. However, a 2020 study did not find these planets and concluded that the radial velocity signals were probably caused by stellar activity. See also *List of nearest stars This list covers all known stars, brown dwarfs, and sub-brown dwarfs within of the Sun. So ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
