U.S. astronomers have captured a direct image of a very rare T-dwarf circling the nearby Sun-like star HD 19467.
This is an artist’s impression of a T-dwarf. Image credit: R. Hurt / NASA.
HD 19467 is a G-type star located in the constellation Eridanus, around 103 light-years away.
Its companion, dubbed HD 19467B, is about 100,000 times fainter than the star.
Initial data on HD 19467B came from the TRENDS high-contrast imaging survey that uses adaptive optics and related technologies to target older, faint objects orbiting nearby stars, and precise measurements were made at the W. M. Keck Observatory. Precise radial velocity measurements were obtained using the HIRES instrument installed on Keck Observatory’s 10-meter, Keck I telescope.
Follow-up observations were taken in 2012 using the NIRC2 instrument on the Keck II telescope with the adaptive optics system revealing HD 19467B.
This image shows the T-class dwarf HD 19467B (arrow). Image credit: Crepp JR et al.
“This object is old and cold and will ultimately garner much attention as one of the most well-studied and scrutinized brown dwarfs detected to date,” said Dr Justin Crepp from the University of Notre Dame, who is the lead author of a paper published in the Astrophysical Journal (arXiv.org).
While astronomers understand the light received from stars relatively well, the spectra from planets is complicated and little understood.
Understanding brown dwarfs such as HD 19467B could be a step towards a fuller understanding of exoplanets.
Dr Crepp said: “with continued follow-up observations, we can use it as a laboratory to test theoretical atmospheric models. Eventually we want to directly image and acquire the spectrum of Earth-like planets. Then, from the spectrum, we should be able to tell what the planet is made out of, what its mass is, radius, age, etc., basically all relevant physical properties.”
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Crepp JR et al. 2014. The TRENDS High-contrast Imaging Survey. V. Discovery of an Old and Cold Benchmark T-dwarf Orbiting the Nearby G-star HD 19467. ApJ 781, 29; doi: 10.1088/0004-637X/781/1/29
