AP Columbae

NASA -- larger image

AP Columbae is a dwarf but unusually bright red star, like
Gl 623 A (M2.5V) and B (M5.8Ve) at lower right. (A 2MASS
Survey image of AP Col may eventually become available
from the NASA Star and Exoplanet Database.)

Previously classed as spectral type M4.5e (with emission lines), the object was observed to be four times brighter than would be expected for a dim red dwarf of that type based on a revised parallax measurement of its distance from the Solar System (Ken Croswell, Science@Now, September 6, 2011). Additional observations and analysis indicated that the object's abnormal luminosity results from it having twice the diameter of a star of that color according to theoretical models. As the object also has a high level of lithium which is destroyed in older stars, AP Columbae was identified as a pre-main sequence object which is still contracting into a young star with a strong magnetic field that generates x-ray bright, UV-Ceti type flares (Riedel et al, 2011; Scholz et al, 2005; and Ball and Bromage, 1995).

Arnold O. Benz, Institute of Astronomy, ETH Zurich

High resolution and jumbo images (Benz et al, 1998).

AP Col exhibits bright flares, like UV Ceti (Luyten 726-8 B) shown
flaring at left. UV Ceti is an extreme example of a flare star that
can boost its brightness by five times in less than a minute, then
fall somewhat slower back down to normal luminosity within two or
three minutes before flaring suddenly again after several hours.

Initially estimated to be 12 to 50 million years old, the object shares the same motion as stars in the young Omicron Velorum cluster (IC 2391), which resides around 450 light-years away in Constellation Vela, next to Columba. At least one of the astronomers suspects a star in that cluster exploded as a supernova and shot out gas filaments that formed new stars over a large region of space. Although separated by hundreds of light-years, these stars move through space together in a group called the Argus Association. As AP Columbae has similar motion with these Argus stars, it probably formed when they did, about 40 million years ago, and so is probably less than one percent as old as our Sun, Sol (which is around 4.7 billion years old). In addition to the variable designation AP Columbae, some alternative names and useful star catalogue numbers for this star are: AP Col, L 523-55, LP 949-015, LTT 2449, SIPS J0604-3433, and 2MASS J06045215.