HD 139664
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HD 139664 is a single star in the southern constellation of Lupus. It has the Bayer designation g Lupi; HD 139664 is the star's identifier from the '' Henry Draper Catalogue''. It has a yellow-white hue and is visible to the naked eye with 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 4.64. The star is located at a distance of 57  light years from the
Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
based on parallax, and it is drifting closer with a radial velocity of −7 km/s. It is a member of the Hercules-Lyra Association of co-moving stars. This is an
F-type main-sequence star An F-type main-sequence star (F V) is a main-sequence, hydrogen-fusing star of spectral type F and luminosity class V. These stars have from 1.0 to 1.4 times the mass of the Sun and surface temperatures between 6,000 and 7,600  K.Tables VII ...
with a stellar classification of F3/5V, 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 ...
. The estimated age is poorly constrained at around one billion years, but the age of the Hercules-Lyra Association to which it belongs is  million years. It has a moderately high rate of spin, showing 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 71.6 km/s. The star has 1.37 times the mass of the Sun and 1.26 times the Sun's radius. It is radiating 3.31 times 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 6,704 K.


Debris disk

A
debris disk A debris disk (American English), or debris disc (Commonwealth English), is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris di ...
has been imaged around this star using the coronagraphic mode of the ACS instrument on the
Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most vers ...
. The disk appears to have a dust maximum at 83 AU from the star and a sharp outer boundary at 109 AU. These features may be caused by gravitational perturbations from planets orbiting the star.


References

{{Stars of Lupus F-type main-sequence stars Circumstellar disks Lupus (constellation) Lupi, g Durchmusterung objects 0594 139664 076829 5825