HN Librae
star in the constellation Libra
HN Librae, also known as Gliese 555, is a red dwarf with at least one orbiting exoplanet in the constellation Libra. With an apparent visual magnitude of 11.32, it can only be viewed through a telescope. The system is located at a distance of 20.4 light years (6.25 parsecs) based on parallax measurements, but is drifting closer to the Sun with a radial velocity of −1.4 km/s. It does not appear to belong to any known stellar moving group or association.
This is an M-type main-sequence star, a red dwarf, with a stellar classification of M4.0V. The chromosphere of this star is weakly active, causing starspots that vary the stellar luminosity as it rotates. It has 29% of the mass of the Sun and 30% of the Sun's girth. On average, the star is radiating just 1% of the luminosity of the Sun from its photosphere at an effective temperature of 3,347 K. The star is spinning slowly with a rotation period of around 96 days.
Planetary system
In 2019, one planet candidate detected by radial velocity was reported in a preprint (never accepted for publication as of 2024), among 118 planets around M dwarf stars. This would have a minimum mass about 30 times that of Earth and orbit with a period of about 450 days.
However, later radial velocity observations by the CARMENES survey published in 2023 did not confirm a planet at this period, but instead found a different planet.
The public source identifies “HN Librae” as star in the constellation Libra. This brief keeps that definition visible, then builds a research path around Librae, star and constellation.
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This entry incorporates text from “HN Librae” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.