Definition
Iota Andromedae (ι And) is a solitary star located in the northern constellation of Andromeda. It is catalogued as a Bayer designation, indicating its position among the brighter stars of the constellation.
Overview
Iota Andromedae is visible to the naked eye under good conditions, exhibiting an apparent visual magnitude of approximately 4.3. The star lies at a distance of roughly 480 light‑years from the Sun, as determined by parallax measurements from the Hipparcos and Gaia missions. It is situated near the western edge of the constellation, close to the asterism that forms the “ladder” of Andromeda.
Etymology/Origin
The name “Iota Andromedae” follows the Bayer designation system introduced by Johann Bayer in his 1603 star atlas Uranometria. In this system, Greek letters are assigned to stars roughly in order of decreasing brightness within a given constellation, with “iota” (ι) being the ninth letter of the Greek alphabet. “Andromedae” is the Latin genitive form of Andromeda, denoting the star’s membership in that constellation.
Characteristics
- Spectral Type: A3 IV‑V, indicating a star that displays characteristics intermediate between a main‑sequence star (luminosity class V) and a subgiant (luminosity class IV).
- Mass: Approximately 2.5 M☉ (solar masses).
- Radius: About 2.4 R☉ (solar radii).
- Luminosity: Roughly 70 L☉ (solar luminosities).
- Effective Temperature: Approximately 8,900 K, giving it a white hue typical of A‑type stars.
- Radial Velocity: The star exhibits a modest radial velocity, moving slowly away from the Solar System.
- Rotational Velocity: It has a projected rotational velocity (v sin i) near 150 km s⁻¹, indicative of relatively rapid rotation for a star of its type.
- Variability: No confirmed photometric variability has been recorded; it is considered photometrically stable within observational limits.
Iota Andromedae does not possess a known companion star and is not associated with any recorded exoplanetary system. Its location near the galactic plane subjects it to moderate interstellar extinction, which slightly dims its observed brightness.
Related Topics
- Bayer Designation: The naming convention used for many stars, combining a Greek letter with the Latin genitive of the constellation name.
- Andromeda Constellation: A northern celestial constellation named after the mythological princess Andromeda; includes notable objects such as the Andromeda Galaxy (M31) and several bright stars (e.g., Alpheratz, Mirach).
- A‑type Stars: A class of stars characterized by strong hydrogen Balmer lines, surface temperatures between 7,500 K and 10,000 K, and often rapid rotation.
- Stellar Evolution: The process by which stars transition from the main sequence to later stages such as subgiant and giant phases; Iota Andromedae’s spectral classification places it in a transitional evolutionary stage.
References
- Hipparcos and Tycho Catalogues (ESA, 1997)
- “The Bright Star Catalogue” (Hoffleit & Jaschek, 1991)
- Gaia Data Release 3 (Gaia Collaboration, 2022)