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HD 211415
HD 211415 is a double star in the constellation Grus. With an apparent visual magnitude of 5.33, it is visible to the naked eye. The annual parallax shift is 72.54 mas, which yields a distance estimate of 45 light years. It has a relatively high proper motion, traversing the celestial sphere at the rate of 93.4 mas per year, and is moving closer to the Sun with a radial velocity of −13 km/s. As of 1994, the two members of this system have an angular separation of 2.884 ″ along a position angle of 34.935°. Their projected separation is 39.8 AU. The pair are most likely gravitationally-bound with an orbit is probably being viewed nearly edge-on and a semimajor axis of around 100 AU. HD 211415 was identified in September 2003 by astrobiologist Margaret Turnbull from the University of Arizona in Tucson as one of the most promising nearby candidates for hosting life based on her analysis of the HabCat list of stars. It is a G-type main-seq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grus (constellation)
Grus (, or colloquially ) is a constellation in the southern sky. Its name is Latin for the crane, a type of bird. It is one of twelve constellations conceived by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Grus first appeared on a celestial globe published in 1598 in Amsterdam by Plancius and Jodocus Hondius and was depicted in Johann Bayer's star atlas ''Uranometria'' of 1603. French explorer and astronomer Nicolas-Louis de Lacaille gave Bayer designations to its stars in 1756, some of which had been previously considered part of the neighbouring constellation Piscis Austrinus. The constellations Grus, Pavo, Phoenix and Tucana are collectively known as the "Southern Birds". The constellation's brightest star, Alpha Gruis, is also known as Alnair and appears as a 1.7-magnitude blue-white star. Beta Gruis is a red giant variable star with a minimum magnitude of 2.3 and a maximum magnitude of 2.0. Six star systems have been foun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radial Velocity
The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is equivalent to the vector projection of the target-observer relative velocity onto the relative direction (geometry), relative direction connecting the two points. In astronomy, the point is usually taken to be the observer on Earth, so the radial velocity then denotes the speed with which the object moves away from the Earth (or approaches it, for a negative radial velocity). Formulation Given a differentiable vector \mathbf \in \mathbb^3 defining the instantaneous position of a target relative to an observer. Let with \mathbf \in \mathbb^3, the instantaneous velocity of the target with respect to the observer. The magnitude of the position vector \mathbf is defined as The quantity range rate is the time derivative of the magnitud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Astronomical Journal
''The Astronomical Journal'' (often abbreviated ''AJ'' in scientific papers and references) is a peer-reviewed monthly scientific journal owned by the American Astronomical Society (AAS) and currently published by IOP Publishing. It is one of the premier journals for astronomy in the world. Until 2008, the journal was published by the University of Chicago Press on behalf of the AAS. The reasons for the change to the IOP were given by the society as the desire of the University of Chicago Press to revise its financial arrangement and their plans to change from the particular software that had been developed in-house. The other two publications of the society, the ''Astrophysical Journal'' and its supplement series, followed in January 2009. The journal was established in 1849 by Benjamin A. Gould. It ceased publication in 1861 due to the American Civil War, but resumed in 1885. Between 1909 and 1941 the journal was edited in Albany, New York. In 1941, editor Benjamin Boss arrange ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Classification
In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grating into a spectrum exhibiting the Continuum (spectrum), rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The ''spectral class'' of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters ''O'', ''B'', ''A'', ''F'', ''G'', ''K'', and ''M'', a sequence from the hottest (''O'' type) to the coo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G-type Main-sequence Star
A G-type main-sequence star (Spectral type: G-V), also often, and imprecisely called a yellow dwarf, or G star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.9 to 1.1 solar masses and an effective temperature between about 5,300 and 6,000 K. Like other main-sequence stars, a G-type main-sequence star is converting the element hydrogen to helium in its core by means of nuclear fusion, but can also fuse helium when hydrogen runs out. The Sun, the star in the center of the Solar System to which the Earth is gravitationally bound, is an example of a G-type main-sequence star (G2V type). Each second, the Sun fuses approximately 600 million tons of hydrogen into helium in a process known as the proton–proton chain (4 hydrogens form 1 helium), converting about 4 million tons of matter to energy. Besides the Sun, other well-known examples of G-type main-sequence stars include Alpha Centauri, Tau Ceti, Capella and 51 Pegasi. The term ''yel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HabCat
The Catalog of Nearby Habitable Systems (HabCat) is a catalogue of star systems which conceivably have habitable planets. The list was developed by scientists Jill Tarter and Margaret Turnbull under the auspices of Project Phoenix, a part of SETI. The list was based upon the Hipparcos Catalogue (which has 118,218 stars) by filtering on a wide range of star system features. The current list contains 17,129 "HabStars". External linksTarget Selection for SETI: 1. A Catalog of Nearby Habitable Stellar Systems Turnbull, Tarter, submitted 31 Oct 2002 (last accessed 19 Jan 2010)Target selection for SETI. II. Tycho-2 dwarfs, old open clusters, and the nearest 100 stars by Turnbull and Tarter, (last accessed 19 Jan 2010)- an article on the NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space progr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tucson
, "(at the) base of the black ill , nicknames = "The Old Pueblo", "Optics Valley", "America's biggest small town" , image_map = , mapsize = 260px , map_caption = Interactive map outlining Tucson , image_map1 = File:Pima County Incorporated and Unincorporated areas Tucson highlighted.svg , mapsize1 = 250px , map_caption1 = Location within Pima County , pushpin_label = Tucson , pushpin_map = USA Arizona#USA , pushpin_map_caption = Location within Arizona##Location within the United States , subdivision_type = Country , subdivision_type1 = State , subdivision_type2 = County , subdivision_name = United States , subdivision_name1 = Arizona , subdivision_name2 = Pima , established_title = Founded , established_date = August 20, 1775 , established_title1 = Incorporated , e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Arizona
The University of Arizona (Arizona, U of A, UArizona, or UA) is a public land-grant research university in Tucson, Arizona. Founded in 1885 by the 13th Arizona Territorial Legislature, it was the first university in the Arizona Territory. The university is part of the Association of American Universities and the Universities Research Association. In the former, it is the only member from the state of Arizona. The university is classified among "R1: Doctoral Universities – Very High Research Activity". The University of Arizona is one of three universities governed by the Arizona Board of Regents. , the university enrolled 49,471 students in 19 separate colleges/schools, including the University of Arizona College of Medicine in Tucson and Phoenix and the James E. Rogers College of Law, and is affiliated with two academic medical centers ( Banner – University Medical Center Tucson and Banner – University Medical Center Phoenix). In 2021, University of Arizona acquired ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Margaret Turnbull
Margaret Carol "Maggie" Turnbull (born 1975) is an American astronomer and astrobiologist. She received her PhD in Astronomy from the University of Arizona in 2004. Turnbull is an authority on star systems which may have habitable planets, solar twins and planetary habitability. She is also an expert on the use of the coronagraph in the direct detection of exoplanets. In 2002, Turnbull developed the HabCat along with Jill Tarter, a catalog of potentially habitable stellar systems. The following year Turnbull went on to further identify 30 particularly suitable stars from the 5,000 in the HabCat list that are within 100 light years of Earth. In 2006, Turnbull drew up two shortlists of just five stars each. The first formed the basis of SETI radio searches with the Allen Telescope Array (Beta Canum Venaticorum, HD 10307, HD 211415, 18 Scorpii, and 51 Pegasi). The second are her top candidates for the Terrestrial Planet Finder (Epsilon Indi, Epsilon Eridani, 40 Eridani, Alpha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semimajor Axis
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longest semidiameter or one half of the major axis, and thus runs from the centre, through a focus, and to the perimeter. The semi-minor axis (minor semiaxis) of an ellipse or hyperbola is a line segment that is at right angles with the semi-major axis and has one end at the center of the conic section. For the special case of a circle, the lengths of the semi-axes are both equal to the radius of the circle. The length of the semi-major axis of an ellipse is related to the semi-minor axis's length through the eccentricity and the semi-latus rectum \ell, as follows: The semi-major axis of a hyperbola is, depending on the convention, plus or minus one half of the distance between the two branches. Thus it is the distance from the center t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Unit
The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits the Sun, from a maximum (aphelion) to a minimum (perihelion) and back again once each year. The astronomical unit was originally conceived as the average of Earth's aphelion and perihelion; however, since 2012 it has been defined as exactly (see below for several conversions). The astronomical unit is used primarily for measuring distances within the Solar System or around other stars. It is also a fundamental component in the definition of another unit of astronomical length, the parsec. History of symbol usage A variety of unit symbols and abbreviations have been in use for the astronomical unit. In a 1976 resolution, the International Astronomical Union (IAU) had used the symbol ''A'' to denote a length equal to the astronomical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Projected Separation
This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outside the atmosphere of Earth. The field of astronomy features an extensive vocabulary and a significant amount of jargon. A B C D E F G H I J K L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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