# HR 2562 b

HR 2562 b is a substellar companion orbiting the star HR 2562. Discovered in 2016 by a team led by Quinn M. Konopacky by direct imaging, HR 2562 b orbits within the inner edge of HR 2562's circumstellar disc—as of April 2023, it is one of only two known brown dwarfs to do so. Separated by roughly 20 astronomical units (3.0×10$^9$ km) from its primary companion, HR 2562 b has drawn interest for its potential dynamical interactions with the outer circumstellar disc.

## Discovery

HR 2562 b was discovered using the Gemini Planet Imager (GPI), which first observed the star HR 2562 in January 2016. In the initial data set, Konopacky and collaborators identified a candidate companion object. As a result, followup observations were conducted within the following month in the infrared K1-, K2-, and J-bands. Within the processed data set, HR 2562 B was confirmed to share a common proper motion with HR 2562, with Konopacky and collaborators announcing its discovery in a paper published on 14 September 2016.

## Host star

HR 2562 b's parent star, HR 2562 (alternatively designated HD 50571 or HIP32775), has a mass of 1.368±0.018 M$_☉$ and a radius of 1.334±0.027 R$_☉$. With an estimated effective temperature of 6597 ± 81K, it is a main-sequence star with the spectral type F5V. It is located 110.92 ± 0.16 light-years (34.007 ± 0.048 pc) from the Sun in the constellation Pictor. HR 2562 is not known to belong to a moving group or stellar cluster.
As with many mid F-type stars, the age of HR 2562 is poorly constrained. Between 1999 and 2011, estimates from various teams of astronomers determined ages ranging from roughly 300 Myr to 1.6 Gyr. In 2018, a team of astronomers led by D. Mesa derived an age of 450+300 −250 Myr using measurements of the star's lithium-temperature relationship.

## Properties
### Orbital properties

Initial observations of HR 2562 B by Konopacky and collaborators yielded a separation of 20.3 ± 0.3 AU (3.037×10$^9$ ± 45,000,000 km), placing it interior to and coplanar with the inner edge of HR 2562's observed debris disc. Further observations of HR 2562 B by the Atacama Large Millimeter Array (ALMA) supported this, yielding a semi-major axis of 19.0+5.7 −4.4 AU, an orbital period of 71.5+35.7 −23.2 yr, and an orbital eccentricity of 0.63+0.32 −0.23. With a probable orbital inclination of 82.8+2.0 −12.5°, HR 2562 B's misalignment angle with the debris disc is either 7+17 −4° or 15+18 −5°. However, the limited coverage of observations still leaves a wide range of possible orbits; both low-eccentricity, coplanar orbits and high-eccentricity, misaligned orbits would be consistent with observation data. However, a highly-misaligned orbit would significantly perturb the disc, suggesting that a low-eccentricity, coplanar solutions are likelier.
Any additional companions around HR 2562 with a mass on the order of 10 M$_J$ should be visible at separations larger than 10 AU, and any companion a few times more massive than Jupiter should be visible to SPHERE's infrared dual-band spectrograph (IRDIS) instrument—thus placing mass restrictions on any additional companions.

### Physical properties

HR 2562 b's exact mass is unknown. The brown dwarf was estimated to be 29 ± 15 M$_J$ in 2021. However, subsequent observations placed an upper mass limit of < 18.5 M$_J$. Its luminosity is about ${\frac {1}{50000}}$ solar luminosity. Its spectral type is L7±3.