Highlights From TESS's First Year ~ Credit: NASA GSFC/USRA
Music: "Elapsing Time" from Killer Tracks
NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered 21 planets outside our solar system and captured data on other interesting events occurring in the southern sky during its first year of science. TESS has now turned its attention to the Northern Hemisphere to complete the most comprehensive planet-hunting expedition ever undertaken.
TESS began hunting for exoplanets (or worlds orbiting distant stars) in the southern sky in July of 2018, while also collecting data on supernovae, black holes and other phenomena in its line of sight. Along with the planets TESS has discovered, the mission has identified over 850 candidate exoplanets that are waiting for confirmation by ground-based telescopes. ...
On July 18, the southern portion of the survey was completed and the spacecraft turned its cameras to the north. When it completes the northern section in 2020, TESS will have mapped over three quarters of the sky. ...
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk. — Garrison Keillor
A young planet and a bright star offer glimpses into the past and future
Data on the brightness of a young star led to the discovery of exoplanet DS Tuc Ab.
Red arrows mark “transits” where the planet crossed between Earth and the planet’s
host star. The large, smooth variations are caused by the star, a result of its youth. Credit: Elisabeth Newton
Researchers at Dartmouth College have discovered a planet orbiting one of the brightest young stars known ... Aged at approximately 45 million years old, the star and its planet could provide valuable information on how planetary bodies form.
Known as an exoplanet because it is outside of the solar system, the planet was found as part of NASA’s Transiting Exoplanet Survey Satellite (TESS) mission. While thousands of exoplanet discoveries have already been made, only a handful have been discovered circling relatively young stars.
Planets can take millions or billions of years to reach maturity. Since that process cannot be observed in real time, researchers are searching for planets around young stars to catch the process in action and learn how planets form and evolve.The exoplanet observed in the Dartmouth research – known as DS Tuc Ab – can be considered a “pre-teen” in planetary time. The planet is no longer growing, but, because of its young age, it is still undergoing rapid changes like losing atmospheric gas as a result of the radiation coming from its host star. ...
DS Tuc Ab is about six times the size of Earth, between the sizes of Neptune and Saturn. Given the size, it likely has a composition similar to that of the giant planets in our solar system. The exoplanet has two suns and makes one full orbit around its main star in just eight days. ...
TESS Hunt for Young and Maturing Exoplanets (THYME):
A Planet in the 45 Myr Tucana–Horologium Association ~ Elisabeth R. Newton et al
NASA’s newest planet hunter, the Transiting Exoplanet Survey Satellite (TESS), has discovered three new worlds — one slightly larger than Earth and two of a type not found in our solar system — orbiting a nearby star. The planets straddle an observed gap in the sizes of known planets and promise to be among the most curious targets for future studies.
TESS Object of Interest (TOI) 270 is a faint, cool star more commonly identified by its catalog name: UCAC4 191-004642. The M-type dwarf star is about 40% smaller than the Sun in both size and mass, and it has a surface temperature about one-third cooler than the Sun’s. The planetary system lies about 73 light-years away in the southern constellation of Pictor. ...
The innermost planet, TOI 270 b, is likely a rocky world about 25% larger than Earth. It orbits the star every 3.4 days at a distance about 13 times closer than Mercury orbits the Sun. Based on statistical studies of known exoplanets of similar size, the science team estimates TOI 270 b has a mass around 1.9 times greater than Earth’s. ...
The other two planets, TOI 270 c and d, are, respectively, 2.4 and 2.1 times larger than Earth and orbit the star every 5.7 and 11.4 days. Although only about half its size, both may be similar to Neptune in our solar system, with compositions dominated by gases rather than rock, and they likely weigh around 7 and 5 times Earth’s mass, respectively. ...
TESS Helps Reveal Multiple Planets, Including Promising World Credit: NASA GSFC/USRA/UMCP
A piping hot planet discovered by NASA’s Transiting Exoplanet Survey Satellite (TESS) has pointed the way to additional worlds orbiting the same star, one of which is located in the star’s habitable zone. If made of rock, this planet may be around twice Earth’s size.
The new worlds orbit a star named GJ 357, an M-type dwarf about one-third the Sun’s mass and size and about 40% cooler that our star. The system is located 31 light-years away in the constellation Hydra. In February, TESS cameras caught the star dimming slightly every 3.9 days, revealing the presence of a transiting exoplanet — a world beyond our solar system — that passes across the face of its star during every orbit and briefly dims the star’s light. ...
The transits TESS observed belong to GJ 357 b, a planet about 22% larger than Earth. It orbits 11 times closer to its star than Mercury does our Sun. This gives it an equilibrium temperature — calculated without accounting for the additional warming effects of a possible atmosphere — of around 490 degrees Fahrenheit (254 degrees Celsius). ...
But while researchers were looking at ground-based data to confirm the existence of the hot Earth, they uncovered two additional worlds. The farthest-known planet, named GJ 357 d, is especially intriguing.
“GJ 357 d is located within the outer edge of its star’s habitable zone, where it receives about the same amount of stellar energy from its star as Mars does from the Sun,” said co-author Diana Kossakowski ... “If the planet has a dense atmosphere, which will take future studies to determine, it could trap enough heat to warm the planet and allow liquid water on its surface.”
Without an atmosphere, it has an equilibrium temperature of -64 F (-53 C), which would make the planet seem more glacial than habitable. The planet weighs at least 6.1 times Earth’s mass, and orbits the star every 55.7 days at a range about 20% of Earth’s distance from the Sun. The planet’s size and composition are unknown, but a rocky world with this mass would range from about one to two times Earth’s size. ...
GJ 357 c, the middle planet, has a mass at least 3.4 times Earth’s, orbits the star every 9.1 days at a distance a bit more than twice that of the transiting planet, and has an equilibrium temperature around 260 F (127 C). TESS did not observe transits from this planet, which suggests its orbit is slightly tilted — perhaps by less than 1 degree — relative to the hot Earth’s orbit, so it never passes across the star from our perspective. ...
TESS Catches Its First Star-Destroying Black Hole
When a star strays too close to a black hole, intense tides break it apart into a
stream of gas. The tail of the stream escapes the system, while the rest of it
swings back around, surrounding the black hole with a disk of debris. This video
includes images of a tidal disruption event called ASASSN-19bt taken by NASA’s
Transiting Exoplanet Survey Satellite (TESS) and Swift missions, as well as an
animation showing how the event unfolded. (Credit: NASA/GSFC/SVS/USRA)
For the first time, NASA’s planet-hunting Transiting Exoplanet Survey Satellite (TESS) watched a black hole tear apart a star in a cataclysmic phenomenon called a tidal disruption event. Follow-up observations by NASA’s Neil Gehrels Swift Observatory and other facilities have produced the most detailed look yet at the early moments of one of these star-destroying occurrences.
“TESS data let us see exactly when this destructive event, named ASASSN-19bt, started to get brighter, which we’ve never been able to do before,” said Thomas Holoien, a Carnegie Fellow at the Carnegie Observatories in Pasadena, California. “Because we identified the tidal disruption quickly with the ground-based All-Sky Automated Survey for Supernovae (ASAS-SN), we were able to trigger multiwavelength follow-up observations in the first few days. The early data will be incredibly helpful for modeling the physics of these outbursts.” ...
ASAS-SN, a worldwide network of 20 robotic telescopes headquartered at Ohio State University (OSU) in Columbus, discovered the event on Jan. 29. Holoien was working at the Las Campanas Observatory in Chile when he received the alert from the project’s South Africa instrument. Holoien quickly trained two Las Campanas telescopes on ASASSN-19bt and then requested follow-up observations by Swift, ESA’s (European Space Agency’s) XMM-Newton and ground-based 1-meter telescopes in the global Las Cumbres Observatory network.
TESS, however, didn’t need a call to action because it was already looking at the same area. The planet hunter monitors large swaths of the sky, called sectors, for 27 days at a time. This lengthy view allows TESS to observe transits, periodic dips in a star’s brightness that may indicate orbiting planets. ...
Dive Into TESS's Southern Sky Panorama Credit: NASA/GSFC/MIT/TESS, USRA, UMCP
Music: "Above Clouds" from Above and Below by Lars Leonhard
The glow of the Milky Way — our galaxy seen edgewise — arcs across a sea of stars in a new mosaic of the southern sky produced from a year of observations by NASA’s Transiting Exoplanet Survey Satellite (TESS). Constructed from 208 TESS images taken during the mission’s first year of science operations, completed on July 18, the southern panorama reveals both the beauty of the cosmic landscape and the reach of TESS’s cameras.
“Analysis of TESS data focuses on individual stars and planets one at a time, but I wanted to step back and highlight everything at once, really emphasizing the spectacular view TESS gives us of the entire sky,” said Ethan Kruse, a NASA Postdoctoral Program Fellow who assembled the mosaic at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Within this scene, TESS has discovered 29 exoplanets, or worlds beyond our solar system, and more than 1,000 candidate planets astronomers are now investigating.
TESS divided the southern sky into 13 sectors and imaged each one of them for nearly a month using four cameras, which carry a total of 16 charge-coupled devices (CCDs). Remarkably, the TESS cameras capture a full sector of the sky every 30 minutes as part of its search for exoplanet transits. Transits occur when a planet passes in front of its host star from our perspective, briefly and regularly dimming its light. During the satellite’s first year of operations, each of its CCDs captured 15,347 30-minute science images. These images are just a part of more than 20 terabytes of southern sky data TESS has returned, comparable to streaming nearly 6,000 high-definition movies.