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The discovery has been published in the Astrophysical Journal. The work was a result of a close collaboration with Dr. Teegarden, an astrophysicist at NASA's Goddard Space Flight Center, and Dr. Steven Pravdo of NASA's Jet Propulsion Laboratory (JPL). Dr Teegarden said of the discovery "Our new stellar neighbour is a pleasant surprise, since we weren't looking for it."
If its distance estimate is confirmed, the newfound star will be the Sun's third-closest stellar neighbour, slightly farther than the Alpha Centauri system, actually a group of three stars more than four light-years away, and Barnard's star, about six light-years away. One light-year is almost nine and a half trillion kilometres.
The new star has only about seven percent of the mass of the Sun, and it is 300,000 times fainter. The star's feeble glow is the reason why it has not been seen until now, despite being relatively close.
The team were looking for white dwarf stars that move rapidly across the sky. Celestial objects with apparent rapid motion are called High Proper Motion (HPM) objects. A HPM object can be discovered in successive images of an area of sky because it noticeably shifts its position while its surroundings remain fixed. The find was made possible with the use of technology used for NEO detection.
For the search the team used the NASA Near Earth Asteroid (NEAT) program, run by the Jet Propulsion Laboratory (JPL), Pasadena, USA. Like HPM stars, asteroids reveal themselves when they shift their position against background stars in successive images. Automated telescopes scan the sky, accumulating thousands of images for the NEAT program.
Although the new star resembles a red dwarf, it actually appears three times dimmer than expected for this kind of star at the initial distance estimate. The star could therefore really be farther than the distance estimate indicates, or if the initial estimate holds, it could have unusual properties that make it shine less brightly than typical red dwarfs. The scientist are now turning their attention to more data from NEAT and other image databases that could reveal faint neighbours of the Sun.
More info: Goddard Space Flight Center
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