HD 76653
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HD 76653 is a single
star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
in the southern
constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...
Vela. It is faintly visible to the naked eye with an apparent visual magnitude of +5.71. Based upon an annual parallax shift of as seen from Earth, it is located 79 
light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...
s from the Sun. The star is moving closer to the Sun with a
radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...
of −6 km/s. It is a probable (96% chance) co-moving companion of the nearby
Delta Velorum Delta Velorum (δ Velorum, abbreviated Delta Vel, δ Vel) is a triple star system in the southern constellation of Vela, near the border with Carina, and is part of the False Cross. Based on parallax measurements, it is approxima ...
; the two have an estimated physical separation of with similar
proper motion Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...
s. Both are likely members of the Ursa Major association. This is an F-type main-sequence star with a
stellar classification In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grati ...
of F6 V. It is larger than the Sun, with 1.22 times the
mass of the Sun The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...
and 1.35 times the Sun's luminosity. The star is radiating 2.72 times the Sun's luminosity from its
photosphere The photosphere is a star's outer shell from which light is radiated. The term itself is derived from Ancient Greek roots, φῶς, φωτός/''phos, photos'' meaning "light" and σφαῖρα/''sphaira'' meaning "sphere", in reference to it ...
at an
effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...
of about 6,296 K. Pace (2013) estimates HD 76653 to be 770 million years old, while Fuhrmann and Chini (2012) date it to an age of around two billion years. However, is an X-ray source with a luminosity of , which is unusually high for the older age estimate. The
metallicity In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as a ...
is near solar and it 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 bulge ...
of 10.3 km/s. HD 76653 displays an infrared excess that suggests the presence of an orbiting debris disk. This excess was detected with the
Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003. Operations ended on 30 January 2020. Spitzer was the third space telescope dedicated to infrared astronomy, f ...
both by the IRS instrument at 30−34 μm and weakly by MIPS at 70 μm. The dust has a temperature of about 73−77 K and is orbiting at a mean distance of 16−18  AU from the host star.


References

{{DEFAULTSORT:HD 76653 F-type main-sequence stars Vela (constellation) 3570 Durchmusterung objects 076653 043797