Teegarden b planet

Teegarden’s Star was discovered in 2003 using asteroid-tracking data that had been collected years earlier. This data set is a digital archive created from optical images taken over a five-year period by the Near-Earth Asteroid Tracking (NEAT) program using two 1 m telescopes located on Maui. The star is named after the discovery team leader, Bonnard J. Teegarden, an astrophysicist at NASA’s Goddard Space Flight Center.

Teegarden’s star showing proper motion at two year intervals.
Astronomers have long thought it was quite likely that many undiscovered dwarf stars exist within 20 light-years of Earth, because stellar-population surveys show the count of known nearby dwarf stars to be lower than otherwise expected and these stars are dim and easily overlooked. Teegarden’s team thought that these dim stars might be found by data mining some of the huge optical sky survey data sets taken by various programs for other purposes in previous years. So they reexamined the NEAT asteroid tracking data set and found this star. The star was then located on photographic plates from the Palomar Sky Survey taken in 1951. This discovery is significant as the team did not have direct access to any telescopes and did not include professional astronomers at the time of the discovery

Teegarden’s Star is identified as a red dwarf, but with a mass of 0.08[3] times that of the Sun it is just above the upper limit of objects classified as brown dwarfs. The inherent low temperatures of such objects explain why it was not discovered earlier,[ since it has an apparent magnitude of only 15.1 (and an absolute magnitude of 17.22 ). Like most red and brown dwarfs it emits most of its energy in the infrared spectrum.

The parallax was initially measured as 0.43 ± 0.13 arcseconds. This would have placed its distance at only 7.50 light-years, making Teegarden’s Star only the third star system in order of distance from the Sun, ranking between Barnard’s Star and Wolf 359.[13] However, even at that time the anomalously low luminosity (the absolute magnitude would have been 18.5) and high uncertainty in the parallax suggested that it was in fact somewhat farther away, still one of the Sun’s nearest neighbors but not nearly as high in the ranking in order of distance. A more accurate parallax measurement of 0.2593 arcseconds was made by George Gatewood in 2009, yielding the now accepted distance of 12.578 light-years.

Planetary system
Observations by the ROPS survey in 2010, published in 2012, showed variation in Teegarden’s star’s radial velocity, though there was insufficient data to make claims of planet detection at that time

In June 2019, scientists conducting the CARMENES survey at the Calar Alto Observatory announced evidence of two Earth-mass exoplanets orbiting the star within its habitable zone.

Both planets are expected to retain a dense atmosphere, and with high likelihood at least one may harbour liquid water

Scientists have discovered a pair of temperate, Earth-sized exoplanet candidates around a nearby star, according to a new paper. What makes this planetary system stand out from all the others discovered in recent years is just how similar one of its planets may be to Earth.

Teegarden’s star is a relatively quiet, ultra-cool star, only 12 light-years away; it’s the 24th closest star to the Sun.


Researchers observed it as part of the larger CARMENES survey for exoplanets, and found evidence for a pair of planets orbiting the star. Their discovery provides us with more chances to potentially find hints of extraterrestrial life.

“After the first discoveries, now we’re getting the context with these planets,” Guillem Anglada-Escude, astronomer at the Queen Mary University of London, told Gizmodo. Basically, we’re seeing more of them and can start identifying patterns and figuring out which of these planets are exceptional. “Maybe from some of them we’ll learn specifically about their atmosphere and can start seeing whether any of these terrestrial planets are Earth-like or not.”

CARMENES is a light spectrum-measuring instrument attached to a 3.5-meter telescope at the the Calar Alto Observatory in Spain that searches for the visible light and infrared signals of exoplanets. As part of this study, it’s surveying “late-type” stars—ones cooler than the Sun. Scientists have already spotted exoplanets in the temperate zones of these kinds of stars, like TRAPPIST-1 and our neighboring Proxima Centauri.

Teegarden’s star is teeny, at around 9 percent the mass of the Sun with a temperature of around 2,900 Kelvin (2,623 Celsius or 4,760 Fahrenheit). That’s quite hot compare to Earth, but very cool for a star. CARMENES detects periodic red and then blue shifts in the light from a star caused by the gravitational pull of orbiting planets. The CARMENES team found evidence of two planets around Teegarden, called Teegarden b and c. Each has an estimated minimum mass of 1.1 times Earth, and orbit their star every 4.91 and 11.4 days, respectively.

One of these planets, Teegarden b, has the highest Earth Similarity Index of any planet yet discovered, according to the paper published in Astronomy and Astrophysics. But the researchers immediately offer a caveat: The index doesn’t take into account how the star’s energy is distributed and how the exoplanet’s atmosphere would look as a result, things that would impact the habitability.

Though it might seem like we’ve been finding exoplanets for a while now—the first confirmed discovery was in 1992—we’re still in the early days, Anglada-Escude explained to Gizmodo. Scientists are just taking a census of these kinds of planets now, so they can later follow up with experiments like the upcoming James Webb Space Telescope and Extremely Large Telescope, which will be able to see these planets in greater detail than current telescopes.

“We are a bit hampered in what we can infer about these planets because we don’t know their radii, but this is a very exciting find, and I hope we will get more observations of this system in the future,” Amy Barr Mlinar, senior scientist at the Planetary Science Institute, told Gizmodo.

Ultimately, it’s going to require patience (maybe a lot of it) before we can truly say we’ve found an Earth-like exoplanet. Until then, we’ll have to content ourself with learning more about hopeful candidates like Teegarden b and, or course, our imaginations.


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