HD 73344 is a star located in the constellationCancer. It has a faintapparent magnitude of 6.9 and therefore can't be seen by the naked eye. It is located 35.2parsecs (115 light-years) away based onparallax measurements. This star hosts three confirmedexoplanets.

HD 73344 is aF-type main-sequence star, a star hotter and brighter than the Sun that fuses atoms of hydrogen into helium at itscore. It is 22% larger, 20% more massive^[6] and 80% more luminous,^[7] and itseffective temperature is 448 degrees hotter, at 6,220 K (5,950 °C). On the other hand, it is younger than the Sun, estimated to be between one and two billion years old, or one-fifth to two-fifths of the solar age. As a consequence, HD 73344 rotates quickly, taking nine days to rotate at its equator (the Sun's rotational period is of 25 days^[8]), and is much moreactive than the Sun.^[6]

Located at 35parsecs (110light-years) from Earth, HD 73344 has anapparent magnitude, that is, its brightness as seen from Earth, of 6.876. Therefore, it is too faint to be seen to thenaked eye, and needs asmall telescope orbinoculars to be seen.^{[2][3][9][10]} Distance and apparent brightness allow theabsolute magnitude—the star's brightness if seen at 10 parsecs (33 light-years)—to be calculated at 4.2.^[5] This star has a nearly circular orbit around theMilky Way, a maximum distance of 40 pc (130 ly) from thegalactic plane and a distance from theGalactic Center varying from 6,880 to 8,840 parsecs (22,400 to 28,800 light-years) across its orbit.^[5]

There are threeexoplanets orbiting HD 73344, all discovered in 2024 via multiplemethods of detection:transit,radial velocity andastrometry.^[11]

The planets'orbital periods range from two weeks to a 16 years. They are all misaligned with each other: Planet b and c have a misalignment of at least 20 degrees, and planet d is misaligned with the inner planets' orbits, in contrast to theSolar System, where the planetary orbits are well aligned. There are two hypotheses that could explain the misalignment: A warpedprotoplanetary disk with misaligned inner and outer components, or dynamical encounters with two or more giant planets in the past.^[11]

HD 73344 b was the first exoplanet discovered in the system, detected via thetransit method. Initially detected as a candidate byK2 in 2018,^[12] it was confirmed by S. Sulis and others in 2024 usingTESS data.^[6] It is classified as asub-Neptune. This planet has around three times the size of Earth as determined by transit observations. Its mass is uncertain, estimated at3.0+2.5
−1.9 times Earth's mass and believed to be no more than ten Earth masses. This implies a low density of0.68+0.59
−0.44 g/cm³, suggesting that its atmosphere is composed ofvolatile elements likehydrogen andhelium. However, further observations are needed, including a more precise mass, to fully characterize its composition and reveal its true nature.^[6]

It is the closest exoplanet to HD 73344, completing an orbit every 16 days at an average distance of 0.131astronomical units (19,600,000 km), less than half of theMercury-Sun distance (0.31 AU). The proximity of its host star also means it has a high temperature. Assuming a nullalbedo, theequilibrium temperature of HD 73344 b is estimated at 910 K (637 °C; 1,178 °F), or 1,066 K (793 °C; 1,459 °F) if it istidally locked.^[6] It has a loworbital eccentricity and appears to be misaligned with its star's spin axis.^[11]

HD 73344 c is asub-Saturn planet, first identified by Suliset al. 2024 (the same discoverers of planet b) viaradial velocity observations^[6] and confirmed by Jingwenet al. some months later.^[11] Its mass, derived via radial velocity observations, is at least 110 Earth masses, equivalent to 0.37Jupiter masses (M_J),^[11] and no more than0.7 M_J, as a mass greater than this would induce an unstable planetary system. Since HD 73344 c does not transit its host star, its radius cannot be measured.^[6]

This planet, like HD 73344 b, lies at a close distance to its host star, with anorbital period of 66 days and an average distance of 0.34 astronomical units, similar toMercury. Theorbital eccentricity is small, at0.12±0.05, and theinclination is not precisely known,^[11] but is no less than 30°^[6] and is at least 20° different from planet b's inclination.^[11] Theequilibrium temperature is estimated to be 562 K (289 °C; 552 °F) assuming a nullalbedo.^[6]

HD 73344 b and c are strongly coupled with each other and undergonodal precession, meaning that theirorbital inclinations vary over time, becoming sometimes misaligned with the host star's spin axis.^[11]

HD 73344 d is aJovian planet, first identified in 27-year baselineradial velocity observations from multiple observatories, and later inHipparcos-Gaiaastrometric observations. Its mass, measured via astrometry, is two and a half times the mass of Jupiter.^[11]

This planet has a wide orbit around HD 73344, and if placed in our Solar System, would lie between that ofJupiter andSaturn, at 6.7 astronomical units. It takes 16 years to complete an orbit around HD 73344. HD 73344 d is therefore classified as a Jupiter analog due to their physical and orbital characteristics being similar.^[11]

• List of exoplanets discovered in 2024
• Kepler-56,HAT-P-11 andPi Mensae, other systems similar orbital architectures and misaligned orbits

• F-type main-sequence stars
• Planetary systems with three confirmed planets
• Henry Draper Catalogue objects
• Hipparcos objects
• Cancer (constellation)

• Articles with short description
• Short description matches Wikidata