HD 45364 is a star in the southern constellation of Canis Major. It is too faint to be visible to the naked eye, having an

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...

of 8.08. The distance to this system is 112 light years based on parallax. It is drifting further away from the Sun with a radial velocity of +16.4 km/s, having come within some 1.5 million years ago. This object is an ordinary G-type main-sequence star with a stellar classification of G8V, which indicates it is generating energy through

core Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (manufacturing), used in casting and molding * Core (optical fiber), the signal-carrying portion of an optical fiber * Core, the centra ...

hydrogen fusion Stellar nucleosynthesis is the creation (nucleosynthesis) of chemical elements by nuclear fusion reactions within stars. Stellar nucleosynthesis has occurred since the original creation of hydrogen, helium and lithium during the Big Bang. As a ...

. It is around 3.4 billion years old and is spinning with a

projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bulg ...

of 1.7 km/s. The star has 88% of the mass of the Sun and 82% of the Sun's radius. It is radiating 56% of the

luminosity of the Sun The solar luminosity (), is a unit of radiant flux ( power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun. One nominal ...

from its photosphere at an effective temperature of 5,540 K. As of August 2008 there are two confirmed

extrasolar planet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

s (or exoplanets) orbiting around it.

Planetary system

HD 45364 is one of only a relative few systems that have had more than one exoplanet discovered in its orbit. The two planets, HD 45364 b and HD 45364 c respectively, were both discovered in August 2008 using the

radial velocity method Doppler spectroscopy (also known as the radial-velocity method, or colloquially, the wobble method) is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in t ...

. The pair was initially believed to be orbiting the host star with a 3:2

mean motion resonance In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relationsh ...

, which means the inner planet is completing three orbits for every two orbits of the outer planet. It was difficult to explain how such resonant configuration of planetary orbits could evolve, mainly due to too high (4-5 times) orbital eccentrities, although planetary system formation models involving hydrodynamic effects were proposed. As in 2022, refined radial-velocity data shows the planetary orbits are more circular and widely spaced, therefore planets are slightly out of mean motion resonance state.

References

{{DEFAULTSORT:HD 45364 G-type main-sequence stars Planetary systems with two confirmed planets Canis Major Durchmusterung objects 045364 Hipparcos objects, 030579