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Created page with '{{image request}} {{Night Sky | image = | designation =HD 115617<br/>HIP 64924 | rightascension =13<sup>h</sup> 18<sup>m</sup> 24.3<sup>s</sup> | declination ...'
{{image request}}
{{Night Sky
| image =
| designation =HD 115617<br/>HIP 64924
| rightascension =13<sup>h</sup> 18<sup>m</sup> 24.3<sup>s</sup>
| declination =−18<sup>o</sup> 18′ 40.3″
| distance =27.8 ly
| constellation =[[Virgo]]
| type =[[Star]]
| dimensions =
| magnitude =Apparent Mag: 4.74<br/>Absolute Mag: 5.07
| redshift =
| radvelocity =-8.2 km/s
| propmotion =RA: -1,069.90 mas/yr<br/>Dec.: -1,063.78 mas/yr
| parallax =117.35 ± 0.69 mas
}}
'''61 Virginis''' is a star located in the [[constellation]] of [[Virgo]] some 27.8 light years from [[Earth]]. It is visible to the unaided eye in sufficiently dark skies as a dim point of light with an apparent magnitude of 4.74. This otherwise nondescript star is noted for the recent discovery of three extrasolar planets in orbit.
==Star System==
61 Virginis has garnished interest because of its similarity to our Sun, and is considered one of the top 100 target stars for NASA's planned [[Terrestrial Planet Finder]] (TPF). This interest has increased in December of 2009 when two "super-Earth" and one [[Neptune]] sized world was announced found orbiting the [[star]].<ref>http://www.ucsc.edu/news_events/text.asp?pid=3439</ref>
In addition to the planets, a large debris disk of icy dust lies in orbit around 61 Virginis either some 95 ±5 to 195 ± 10 AUs away if the dust are black bodies (emit no electromagnetic [[radiation]]), or 120 ±20 to 220 ±10 AUs away, if the dust emits radiation in the [[infrared]].<ref name="vogt">http://eprintweb.org/S/article/astro-ph/0912.2599</ref> This dust ring has open the hypothetical possibility of a fourth world far out from the star, shepherding the dust ring.
===The Star===
61 Virginis is a yellow-orange main sequence dwarf of spectral type G5-6 V. The star is a near twin of our own [[Sun]], with 92 to 96 percent of its mass, and 94 to 98 percent of its diameter.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005ApJS..159..141V</ref> The star is also somewhat less luminous in comparison, with a total bolometric luminosity of 81 percent that of our Sun.<ref>http://adsabs.harvard.edu/abs/2008A%26A...487..373S</ref> The star is considered "metal-rich" with a [[metallicity]] 1.1 times that of our Sun, based on the abundance of [[iron]] in the star.
Because 61 Virginis has a rotation of only 29 days and is photometically stable, it is believed to be an older star with an estimated age of 9.8 billion years.<ref name="vogt">http://eprintweb.org/S/article/astro-ph/0912.2599</ref> Further measurements show the star is orbiting the core of the [[Milky Way]] with an orbital eccentricity of 0.15, which is typically of old disk stars.<ref>http://adsabs.harvard.edu/abs/1999A&A...348..897L</ref>
===61 Virginis b===
'''61 Virginis b''' is the closest known planet to the star 61 Virginis, orbiting at a distance of only 0.050201 AU, with an orbital eccentricity of 0.12. At this distance, the world would complete an orbit in only 4.215 days. The planet has a mass 5.1 ±0.5 times of the [[Earth]], classifying the world as a "super Earth". If the planet has a solid, terrestrial surface, it would be mostly molten rock.<ref name="vogt2">http://arxiv.org/abs/0912.2599v1</ref>
===61 Virginis c===
'''61 Virginis c''' is the second closest known planet to the star 61 Virginis. The world has a minimum mass 18.2 times that of the Earth making it likely a small gas giant not unlike [[Uranus]] or [[Neptune]]. The world orbits at a mean distance of 0.2175 AU with an eccentricity of 0.14. At this distance, the planet would orbit in only 38 days.<ref name="vogt2">http://arxiv.org/abs/0912.2599v1</ref>
===61 Virginis d===
'''61 Virginis d''' is the farthest known planet that orbits the star 61 Virginis. The planet has the greatest orbital eccentricity of the 61 Virginis system, with an eccentricity of 0.35. The mean distance of the world's orbit is 0.476 AU, a little less then one half of the size of the orbit of the Earth. The world is also the most massive known at 23 times the mass of the Earth. As such, the world is most likely a gas giant not unlike [[Uranus]] or [[Neptune]].<ref name="vogt2">http://arxiv.org/abs/0912.2599v1</ref>
For an [[terrestrial planet|Earth-like]]planet to have liquid [[water]] on its surface, it would need to be centered around 0.9 AU from the star. Such a world would have an orbital period of roughly 317 days. At this time, such a small world would be extremely difficult to detect with present technology.
==References==
{{reflist}}
[[Category: Astronomy]]
{{Night Sky
| image =
| designation =HD 115617<br/>HIP 64924
| rightascension =13<sup>h</sup> 18<sup>m</sup> 24.3<sup>s</sup>
| declination =−18<sup>o</sup> 18′ 40.3″
| distance =27.8 ly
| constellation =[[Virgo]]
| type =[[Star]]
| dimensions =
| magnitude =Apparent Mag: 4.74<br/>Absolute Mag: 5.07
| redshift =
| radvelocity =-8.2 km/s
| propmotion =RA: -1,069.90 mas/yr<br/>Dec.: -1,063.78 mas/yr
| parallax =117.35 ± 0.69 mas
}}
'''61 Virginis''' is a star located in the [[constellation]] of [[Virgo]] some 27.8 light years from [[Earth]]. It is visible to the unaided eye in sufficiently dark skies as a dim point of light with an apparent magnitude of 4.74. This otherwise nondescript star is noted for the recent discovery of three extrasolar planets in orbit.
==Star System==
61 Virginis has garnished interest because of its similarity to our Sun, and is considered one of the top 100 target stars for NASA's planned [[Terrestrial Planet Finder]] (TPF). This interest has increased in December of 2009 when two "super-Earth" and one [[Neptune]] sized world was announced found orbiting the [[star]].<ref>http://www.ucsc.edu/news_events/text.asp?pid=3439</ref>
In addition to the planets, a large debris disk of icy dust lies in orbit around 61 Virginis either some 95 ±5 to 195 ± 10 AUs away if the dust are black bodies (emit no electromagnetic [[radiation]]), or 120 ±20 to 220 ±10 AUs away, if the dust emits radiation in the [[infrared]].<ref name="vogt">http://eprintweb.org/S/article/astro-ph/0912.2599</ref> This dust ring has open the hypothetical possibility of a fourth world far out from the star, shepherding the dust ring.
===The Star===
61 Virginis is a yellow-orange main sequence dwarf of spectral type G5-6 V. The star is a near twin of our own [[Sun]], with 92 to 96 percent of its mass, and 94 to 98 percent of its diameter.<ref>http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2005ApJS..159..141V</ref> The star is also somewhat less luminous in comparison, with a total bolometric luminosity of 81 percent that of our Sun.<ref>http://adsabs.harvard.edu/abs/2008A%26A...487..373S</ref> The star is considered "metal-rich" with a [[metallicity]] 1.1 times that of our Sun, based on the abundance of [[iron]] in the star.
Because 61 Virginis has a rotation of only 29 days and is photometically stable, it is believed to be an older star with an estimated age of 9.8 billion years.<ref name="vogt">http://eprintweb.org/S/article/astro-ph/0912.2599</ref> Further measurements show the star is orbiting the core of the [[Milky Way]] with an orbital eccentricity of 0.15, which is typically of old disk stars.<ref>http://adsabs.harvard.edu/abs/1999A&A...348..897L</ref>
===61 Virginis b===
'''61 Virginis b''' is the closest known planet to the star 61 Virginis, orbiting at a distance of only 0.050201 AU, with an orbital eccentricity of 0.12. At this distance, the world would complete an orbit in only 4.215 days. The planet has a mass 5.1 ±0.5 times of the [[Earth]], classifying the world as a "super Earth". If the planet has a solid, terrestrial surface, it would be mostly molten rock.<ref name="vogt2">http://arxiv.org/abs/0912.2599v1</ref>
===61 Virginis c===
'''61 Virginis c''' is the second closest known planet to the star 61 Virginis. The world has a minimum mass 18.2 times that of the Earth making it likely a small gas giant not unlike [[Uranus]] or [[Neptune]]. The world orbits at a mean distance of 0.2175 AU with an eccentricity of 0.14. At this distance, the planet would orbit in only 38 days.<ref name="vogt2">http://arxiv.org/abs/0912.2599v1</ref>
===61 Virginis d===
'''61 Virginis d''' is the farthest known planet that orbits the star 61 Virginis. The planet has the greatest orbital eccentricity of the 61 Virginis system, with an eccentricity of 0.35. The mean distance of the world's orbit is 0.476 AU, a little less then one half of the size of the orbit of the Earth. The world is also the most massive known at 23 times the mass of the Earth. As such, the world is most likely a gas giant not unlike [[Uranus]] or [[Neptune]].<ref name="vogt2">http://arxiv.org/abs/0912.2599v1</ref>
For an [[terrestrial planet|Earth-like]]planet to have liquid [[water]] on its surface, it would need to be centered around 0.9 AU from the star. Such a world would have an orbital period of roughly 317 days. At this time, such a small world would be extremely difficult to detect with present technology.
==References==
{{reflist}}
[[Category: Astronomy]]
