Definition
109 Piscium is a G-type main‑sequence star located in the constellation Pisces. It is catalogued as HD 9826 and is known to host at least one confirmed exoplanet.
Overview
The star lies at a distance of approximately 69 light‑years (21 parsecs) from the Sun and is visible to the naked eye under dark‑sky conditions with an apparent visual magnitude of about 5.3. 109 Piscium is part of the solar neighborhood and has been studied for its stellar properties and planetary system.
Etymology/Origin
The designation “109 Piscium” follows the Flamsteed numbering system, in which stars are numbered in order of increasing right ascension within a given constellation—in this case, Pisces. The number 109 indicates its sequential position in the catalog of stars in that constellation.
Characteristics
- Spectral type: G1.5 V (yellow dwarf)
- Mass: ≈1.07 M☉ (solar masses)
- Radius: ≈1.17 R☉ (solar radii)
- Luminosity: ≈1.6 L☉ (solar luminosities)
- Effective temperature: ≈5,840 K
- Age: Estimated between 4.0 and 5.5 billion years
- Metallicity: Slightly higher than solar, with [Fe/H] ≈ +0.12
- Rotational velocity: ≈4 km s⁻¹
- Parallax: 47.7 mas (milliarcseconds), yielding the distance stated above.
Planetary System
In 1999, a massive exoplanet designated 109 Piscium b (also known as HD 9826 b) was detected via the radial‑velocity method. The planet has a minimum mass of roughly 2.5 Jupiter masses (M_J) and orbits the star with a period of about 6.2 days at a semi‑major axis of ~0.07 AU, placing it well within the star’s habitable zone. No additional companions have been confirmed as of the latest surveys, though the system remains a target for further observation.
Related Topics
- Flamsteed designation – the naming convention used for 109 Piscium.
- HD 9826 – the star’s entry in the Henry Draper Catalogue.
- Exoplanet detection methods – notably the radial‑velocity technique employed for 109 Piscium b.
- G-type main‑sequence stars – the broader class of stars to which 109 Piscium belongs.
- Nearby stellar neighbourhood – the region of space within roughly 100 light‑years containing stars like 109 Piscium.