Pi3 Orionis 2?

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NASA

Pi3 Orionis A is a yellowish star that is
brighter than our Sun, Sol. (See a Digitized
Sky Survey image of Pi3 Orionis
from the Nearby Stars Database.)

System Summary

This (possibly multiple) star system is located about 26.2 light-years (ly) away from our Sun, Sol. It lies at the western edge (04:49:50.41+06:57:40.59, ICRS 2000.0) of Constellation Orion, the Hunter -- southeast of Aldebaran (Alpha Tauri), south of Pi1 and Pi2 Orionis, and north of Pi4 Orionis. As Pi3 Orionis 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.

JPL, CalTech, NASA

Larger illustration

Astronomers have identified Pi3
Orionis as a prime target for the
Terrestrial Planet Finder (TPF),
now planned for launch between
2014 and 2020.

Pi3 Orionis

This star is a white-yellow main sequence dwarf star of spectral and luminosity type F6 V, with maybe 1.3 times Sol's mass, 1.3 times its diameter (Perrin and Karoji, 1987), and three times of its luminosity. It may be anywhere from 20 to 151 percent as enriched as Sol with elements heavier than hydrogen ("metallicity"), based on its abundance of iron (Cayrel de Strobel et al, 1991, page 10). Pi3 Orionis A is a New Suspected Variable designated NSV 1731. Star A has a probable optical companion (Abt and Levy, 1976, page 20) and may have a spectroscopic companion that speckle interferometry has not been able to resolve (Hartkopf and McAlister, 1984). Useful star catalogue numbers for the star include: Pi3 Ori, 1 Ori, HR 1543*, Gl 178, Hip 22449, HD 30652, BD+06 762, SAO 112106, FK5 1134, and LTT 11517.

Pi3 Orionis B?

According to the Yale Bright Star Catalogue, 1991 5th Revised Edition notes entry for HR 1543, its visual companion may be optical.

Hunt for Substellar Companions

The distance from star A where an Earth-type planet would be "comfortable" with liquid water is centered around 1.7 AU -- beyond the orbital distance of Mars in the Solar System. Astronomers are hoping to use NASA's Terrestrial Planet Finder (TPF) and the ESA's Darwin planned groups of observatories to search for a rocky inner planet in the so-called "habitable zone" (HZ) around Pi3 Orionis. As currently planned, the TPF will include two complementary observatory groups: a visible-light coronagraph to launch around 2014; and a "formation-flying" infrared interferometer to launch before 2020, while Darwin will launch a flotilla of three mid-infrared telescopes and a fourth communications hub beginning in 2015.

Closest Neighbors

The following star systems are located within 10 light-years of Pi3 Orionis.

Star System	Spectra & Luminosity	Distance (light-years)
Ross 41	M3.5-5 V	5.1
BD-05 1123 AB	K3 V ?	6.7
G 99-47	DA9 /VII	7.3
BD+18 683	M2.5 Ve ?	7.5
LP 656-38	M3.5 V	8.3
L 879-14	DQ7 /VII	8.6
LP 415-636	M4.5 Ve	8.8
Ross 47	M4 V	9.1
G 99-44	DZ9 /VII	9.3
LTT 11392	M4 Ve	9.4
BD-03 1123	M1.5 V	9.5
Chi1 Orionis3?	G0 V ? ?	9.9
LP 378-541	M2 V	9.3

Other Information

Up-to-date technical summaries on these stars can be found at: the Astronomiches Rechen-Institut at Heidelberg's ARICNS, the Nearby Stars Database, and the Research Consortium on Nearby Stars (RECONS). Additional information may be available at Roger Wilcox's Internet Stellar Database.

Constellation Orion is easily visible in the Northern Hemisphere. In Greek mythology, Orion (the Great Hunter) died after being stung by by the scorpion (Constellation Scorpius). For more information about the stars and objects in this constellation and an illustration, go to Christine Kronberg's Orion. For another illustration, see David Haworth's Orion.

For more information about stars including spectral and luminosity class codes, go to ChView's webpage on The Stars of the Milky Way.