Iota Persei

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NASA

Iota Persei is a yellow-orange star
like our Sun, Sol. (See a Digitized
Sky Survey image of Iota Persei
from the Nearby Stars Database.)

System Summary

Iota Persei is located about 34.4 light-years (ly) from Sol. It lies in the northern part of (3:9:4.0+49:36:47.8, ICRS 2000.0) of Constellation Perseus, the mythical Greek Hero who uses the Gorgon Medusa's severed head to change Cetus into stone. The star can be found next to Mirfak (Alpha Persei), northwest of Delta Persei, northeast of Algol (Beta Persei), and southwest of Tau, Eta, and Gamma Persei. As Iota Persei 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 Iota
Persei as a prime target for the
Terrestrial Planet Finder (TPF),
now planned for launch between
2014 and 2020.

The Star

Iota Persei is a yellow-orange main sequence dwarf star of spectral and luminosity type G0 V. Bigger and brighter than Sol, the star may have as much as 1.3 times Sol's mass, around 1.08 times its diameter (Pasinetti-Fracassini et al, 2001; Blackwell and Lynas-Gray, 1994; and Johnson and Wright, 1983, page 653), and 2.2 times its luminosity. It appears to be 1.08 times as enriched than Sol in elements heavier than hydrogen ("metals") based on its abundance of iron (B.J. Taylor, 2003). Based on chromospheric activity, Iota Persei appears to be around 8.1 billion years old -- much older than Sol's 4.6 billion years (Don C. Barry, 1988, page 438). According to the the Astronomiches Rechen-Institut at Heidelberg's ARICNS, the star is a suspected "a double" catalogued as Hei4, but the evidence is "far from solid" (Wulff Dietz Heintz, 1988, page 1074, see: BD+49 857). Highly evolved with a lot of helium ash at its core, the star is close to becoming a subgiant (Wulff Dietz Heintz, 1988, page 1074, see: BD+49 857). Useful catalogue numbers and designations for the star include: Iot Per, HR 937*, Gl 124, Hip 14632, HD 19373, BD+49 857, SAO 38597, FK5 112, LHS 166, LTT 11020, LFT 256, and Hei4.

Hunt for Planetary Objects

Past radial velocity analysis suggests that giant planets of one tenth to 10 times the mass of Jupiter do not exist within 0.1 to four AUs of Iota Persei (Cummings et al, 1999). If so, then conditions would be more favorable for the existence of stable orbit for an Earth-like planet (with liquid water) centered around 1.5 AU from around Iota Persei -- around the orbital distance of Mars in the Solar System. Such a planet would have an orbital period of around 1.6 years. 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 Iota Persei. 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 table includes all star systems known to be located within 10 light-years (ly), plus more bright stars within 10 to 20 ly, of Iota Persei.

Star System	Spectra & Luminosity	Distance (light-years)
Theta Persei 2?	F7 V ?	3.4
G 174-14	DC9 /VII	3.5
BD+47 612	M1.5 Ve	6.7
BD+52 857	K8 V	8.4
AC+56 13511	M3 V	9.8
Ross 15	M4 Ve	9.9
G 244-47	M4 V	9.9
* plus bright stars *		. . .
Delta Trianguli 2	G0.5 Ve ?	11
HR 483 AB	G1.5 V ?	13
Mu Cassiopeiae 2	G5 VIp M V-VI	14
Upsilon Andromedae 2	F8 V M4.5 V	16
Capella 4	G8-K0 IIIe G1 III M1 V M4-5 V	16
BD+37 783	G5 V	18
Eta Cassiopeiae 2	G3 V K7 V	18
Lambda Aurigae	G0-5 V-VI	18
107 Piscium	K1 V	20

Other Information

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

Constellation Perseus is one of the larger constellations of the northern hemisphere. According to the Ancient Greeks, Perseus was the son of Zeus and the mortal Danaë. After an oracle told Danaë's father that his grandson would kill him one day, however, he set Danaë and Perseus adrift in a trunk. Rescued by a fisherman, the two lived on his island until its king sought to have Danaë for himself by sending Perseus away to kill the Medusa. Although the Medusa was as a beautiful woman with long and glowing hair, pride led Medusa to compare her beauty self with Athena, the Goddess of Wisdom and War, who then turned Medusa into a hideous monster with writhing and hissing snakes for hair, a sight that turned onlookers to stone. Perseus was favored by Athena, who lent Perseus her bright shield, and the wing-footed god, Hermes, who lent his winged shoes. So equipped, Perseus managed to cut off Medusa's head and stuffed it into a sack by looking at her reflection in Athena's shield. The celestial figure of Perseus is thought to held the head of Medusa in his hand, where the star Algol or Beta Persei represents her evil eye. For more information about the stars and objects in this constellation and an illustration, go to Christine Kronberg's Perseus. For another illustration, see David Haworth's Perseus.

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