A Lookback on TESS’s First Year

NASA’s Transiting Exoplanet Survey Satellite (TESS) completed its first year of scientific observations between July 2018 and July 2019. More than 1100 candidate exoplanets in the vicinity of the Sun were discovered in the southern sky during this campaign using the transit method. This first rich catalogue of our neighbouring planets will soon be published in an issue of the Astrophysical Journal Supplements.

At the American Astronomical Society’s 2020 Winter Meeting in Honolulu, Hawai’i in January, the TESS science team offered the public and the astronomical community a review of the mission’s first year. During these first twelve months, 1100 new candidate exoplanets have already been detected in the solar neighbourhood; at most at a distance of 3000 lightyears from Earth, but including several exoplanets located less than 25 lightyears away. During its entire mission, the famous Kepler satellite enabled the discovery of over 2600 exoplanets using the transit method. TESS has taken over where Kepler left off and focuses in particular on the stars closest to the Sun.

TOI 700d is the very first Earth-sized exoplanet found in its star’s habitable zone discovered by the TESS satellite. (Credit: NASA GSFC)

Of the 1100 candidate exoplanets that TESS is believed to have discovered between July 2018 and July 2019, 37 have already been confirmed thanks to followup observations from other telescopes and published in scientific papers. Some of the most interesting exoplanets found in this catalogue include an Earth-sized planet, TOI (TESS Object of Interest) 700d, which is found in the habitable zone of its star. It appears to have at least two other sister planets in the same system but these are orbiting too close to the central star to contain water in liquid form. The exoplanetary system is about 100 lightyears away from Earth.

An artistic representation of the surface of the exoplanet in the LT 1445ABC trinary system. The three stars of the system can be seen in this sunset scene. (Credit: ESO/M. Kornmesser)

This first TESS catalogue also contains several systems with multiple stars. An exoplanet in a binary system (with two stars) was discovered in the TESS data by a high school student working at NASA during an internship. Remarkably, an exoplanet in a trinary system (with three stars) named LT 1445ABC was also detected in the TESS data. This planet is located only 22.5 lightyears from Earth, and will likely be an excellent target for the James Webb Space Telescope to inspect it more closely and determine whether it has an atmosphere.

These initial results of the TESS mission are very promising and are even beyond the high expectations of the scientific community. In addition to the 1100 candidate exoplanets discovered in the first year of TESS, 400 more candidates have been discovered in its second year, which is still ongoing. The SPIRou instrument, which is already operational at the Canada France Hawai’i Telescope, as well as the NIRPS instrument and the JWST telescope, both of which will soon be in operation, will be able to perform important followup observations on TESS targets to better understand our closest neighbouring exoplanets.

Read More

Official TESS mission website
Scientific paper on TOI 700d
Scientific paper on LT 1445ABC