Nu2 Lupi
Nu2 Lupi |
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NASA
Nu2 Lupi is a yellow-orange star
like our Sun, Sol. 2MASS
Survey
image
of Nu2 Lupi from the
NASA
Star and Exoplanet Database.)
System Summary
Nu2 Lupi is located about 47.5 light-years (ly) from Sol. It lies in the southern part of (15:21:48.1-48:19:3.5, ICRS 2000.0) of Constellation Lupus, the Wolf. The star can be found: near Nu1 and Kappa1 Lupi; north of Zeta Lupi; southwest of Epsilon, Gamma, and Delta Lupi; south of Beta Lupi; and east of Kakkab (Alpha Lupi). As Nu2 Lupi has become one of the top 100 target stars for NASA's planned Terrestrial Planet Finder (TPF), images of this star and its position relative to the Milky Way in Earth's night sky are now available from the TPF-C team. On September 12, 2011, the European Southern Observatory provided a link to a paper describing the detection of three planetary candidates (including at least one a second super-Earth "b") in inner orbits around Nu2 Lupi, or HD 136352 (Mayor et al, 2011, Table 1 and 19; and Udry et al, 2011, in preparation).
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| Orbital Distance (a=AUs) | Orbital Period (P=years) | Orbital Eccentricity (e) | Orbital Inclination (i=degrees) | Mass (Earths) | Diameter (Earths) | Density (Earths) | Surface Gravity (Earths) | Metallicity (Solar) | |
| Nu2 Lupi | 0.0 | ... | ... | ... | 340,000 | 108 | ... | ... | 0.58 |
|---|---|---|---|---|---|---|---|---|---|
| Planet "b" | 0.093 | 0.032 | 0.18 | ? | =>5.4 | >1 | ... | ... | ... |
| Planet "c" | 0.167 | 0.076 | 0.16 | ? | =>11.4 | >1 | ... | ... | ... |
| Planet "d" | 0.411 | 0.293 | 0.43 | ? | =>9.6 | >1 | ... | ... | ... |
| Inner H.Z. Edge? | 0.692 | 0.571 | 0.0 | ... | ... | ... | ... | ... | ... |
| Outer H.Z. Edge? | 1.385 | 1.614 | 0.0 | ... | ... | ... | ... | ... | ... |
Nu2 Lupi is a yellow-orange main sequence dwarf star of spectral and luminosity type G2-5 V. Similar to Sol (Giusa Cayrel de Strobel, 1996), this "Solar analogue" may have 1.02 times Sol's mass (NASA Stars and Exoplanet Database, based on the interpolation table of David F. Gray ), around 99 percent of its diameter (Pasinetti-Fracassini et al, 2001; and Johnson and Wright, 1983, page 683), and 97 percent of its luminosity. It appears to be only around 58 percent as enriched than Sol in elements heavier than hydrogen ("metals") based on its abundance of iron (B.J. Taylor, 2003). Useful catalogue numbers and designations for the star include: Nu2 Lup, HR 5699, Gl 582, Hip 75181, HD 136352, CD-47 9919, CP(D)-47 7075, SAO 225697, LHS 395, LTT 6225, LFT 1200, and LPM 565.
Estimates based on one type of model calculations performed for the NASA Star and Exoplanet Database indicate that the inner edge of Nu2 Lupi's habitable zone could be located around 0.692 AU from the star, while the outer edge edge lies around 1.385 AUs. The orbital distance from HD 85512 where an Earth-type planet may have liquid water on its surface is centered around only 0.979 AU from this Sol-type star-- inside the orbital distance of Venus but just inside the orbital distance of Venus in the Solar System -- where a planet probably would have an orbital period of about 350 days or 95.9 percent of an Earth year. However, given its conjectured young age, an Earth-sized planet is not likely to have developed an oxygen-rich atmosphere but is likely to be under heavy bombardment by asteroids and comets.
JPL,
CalTech,
NASA
Larger illustration
Astronomers have identified Nu2
Lupi as a prime target for the
Terrestrial
Planet Finder (TPF),
now indefinitely delayed.
Planetary System
Planet "b" - Planetary candidate "b" appears to be a super-Earth with around 5.3 +/- 0.6 Earth-masses in a hot, innermost orbit around this star . The planet completes an orbit around Nu2 Lupi in 11.577 +/- 0.006 days at an average distance of 0.0933 +/- 0.0015 AU in an mildly elliptical orbit with an eccentricity e = 0.18 +/- 0.14.
Planet "d" - Planetary candidate "d" is probably around the maximum size of a super-Earth with around 9.6 +/- 1.9 Earth-masses in a outer orbit around this star. The planet completes an orbit around Nu2 Lupi in 107 +/- 1 days at an average distance of 0.411 +/- 0.007 AU in an elliptical orbit with an eccentricity e = 0.43 +/- 0.24.
Closest Neighbors
The following table includes all star systems known to be located within 10 light-years (ly), plus more bright stars within 10 to 20 ly, of Nu2 Lupi.
| Star System | Spectra & Luminosity | Distance (light-years) |
| CD-42 10934 | K5 V | 7.0 |
| CD-56 6221 | K3 V | 9.0 |
| HR 5864 AB | G6 V-IV DA7 /VII | 9.9 |
| * plus bright stars * | . . . | |
| HR 5825 | F5 V-IV | 11 |
| HD 147513 / HR 6094 AB | G3-5 V DA2 /VII | 12 |
| Beta Trianguli Australis 2? | F2 IV-III | 14 |
| Alpha Circini 3? | A3-F1 V-IIIp K5 V ? | 16 |
| Zeta Trianguli Australis 2 | F9-G0 V ? | 19 |
| Mu Arae | G3-5 V | 19 |
Other Information
Up-to-date technical summaries on these stars can be found at: Jean Schneider's Extrasolar Planets Encyclopaedia; the Astronomiches Rechen-Institut at Heidelberg's ARICNS, and the NASA Star and Exoplanet Database. Additional information may be available at Roger Wilcox's Internet Stellar Database.
Known as an unidentified animal called Therion to the Ancient Greeks (possibly the Erymanthian boar captured alive by Hercules as one of his tasks), the constellation was linked with the Wolf by the time of Johannes Bayer (1572-1625) For more information on stars and other objects in Constellation Eridanus, go to Christine Kronberg's Lupus. An illustration is available at David Haworth's Lupus.
For more information about stars including spectral and luminosity class codes, go to ChView's webpage on The Stars of the Milky Way.
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Note: Nominated as a "notable nearby star" by Ronald Botterweg. © 2003-2011 Sol Company. All Rights Reserved. |