astronomy Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...

, the Columba association is a nearby Myr old stellar association. The association is named after the constellation Columba which contains many of the stars first recognized in the group.

Special interest

Stars in young associations are a popular target for professional

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

s. The stars are often surrounded by

circumstellar disks A circumstellar disc (or circumstellar disk) is a torus, pancake or ring-shaped accretion disk of matter composed of gas, dust, planetesimals, asteroids, or collision fragments in orbit around a star. Around the youngest stars, they are the re ...

, discs of dust and other planet forming matter around a young star, and young planets that still glow in the

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

spectrum, which makes it easier to directly image, using the light reflected off of the planets to obtain an image of the planets. The most famous star in the Columba association is which has four directly imaged planets. The group was at first not recognized as an individual group, but stars within the group were first assigned to the Great Austral Young Association (GAYA), because it showed similar movement and distance compared with two nearby groups. Only later it became clear that GAYA is subdivided into three groups: the Tucana-Horologium association, the Carina association and the Columba association. The brightest star in the association is the massive star HD 32309, with a spectral type of B9Vann and an

apparent 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 ...

of 4.90 . The association also contains several A-type and F-type stars, such as Omega Aurigae,

HR 8799 HR 8799 is a roughly 30 million-year-old main-sequence star located away from Earth in the constellation of Pegasus. It has roughly 1.5 times the Sun's mass and 4.9 times its luminosity. It is part of a system that also ...

, 26 Geminorum and AS Columbae. It also contains several other

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as e ...

s, such as V1358 Orionis, RT Pictoris, DK Leonis, V909 Orionis and GJ 1284. The stars HD 30447 and HD 35847 are members of the group with directly imaged

debris disks Debris (, ) is rubble, wreckage, ruins, litter and discarded garbage/refuse/trash, scattered remains of something destroyed, or, as in geology, large rock fragments left by a melting glacier, etc. Depending on context, ''debris'' can refer to ...

NICMOS Archival Images of Five Debris Disks

Footnotes

References

{{reflist, 25em Stellar associations Columba (constellation)

Special interest

See also

Footnotes

References