“The discovery of a terrestrial planet around a nearby M dwarf during the first TESS observing sector suggests that the prospects for future discoveries are bright. It is worth remembering that 90 percent of the sky has not yet been surveyed by either TESS or Kepler,” NASA reports.
The satellite’s “first light science image,” taken last August, covers a swath of the Southern Sky showing stars and constellations and the Large and Small Magellanic Clouds, which are nearby satellite galaxies of the Milky Way. Within this first patch of sky to be surveyed TESS (Transiting Exoplanet Survey Satellite), has already identified at least 73 stars that might harbor exoplanets, most of them new to astronomers, according to George Ricker, an astrophysicist at the Massachusetts Institute of Technology who leads the project. They all need to be peer confirmed by other astronomers.
TESS was launched on April 18 from Cape Canaveral aboard a SpaceX Falcon 9 rocket, reports the New York Times, and is “now ensconced in a looping orbit of the Earth that takes it all the way out to the moon and then back close to Earth to dump its data. It has four cameras that stare at orange slices of the sky from pole to equator for 27 days at a time.”
Tucked amidst its amazing haul is was Pi Mensae c—a small, Earth-like planet located nearly 60 light-years from our Solar System is the first exoplanet detected by NASA’s new TESS satellite launched on April 18, 2018, and it began operations on July 25. In an early test of its powers, the satellite nabbed its first light image on August 7, which we finally got to see this past Monday.
Image below shows host star Pi Mensae (big black dot), around which the new planet was discovered. The red lines show the boundary of the TESS aperture. (Science and Engineering Research Council J survey/C. X. Huang et al.,)
The preliminary survey of Pi Mensae c suggests it contains water, methane, hydrogen, and helium, in addition to a rocky, iron core. Future observations made by the Gaia spacecraft and the yet-to-be-launched James Webb Space Telescope will likely reveal more about this relatively nearby exoplanet.
TESS is an alien planet hunter, using four 10-centimeter optical telescopes, that repeatedly scan wide fields of space, and monitors the brightness of candidate stars. This data is then analyzed by NASA astronomers, who look for periodic dips in a star’s brightness—a possible sign of an orbiting, or transiting, exoplanet passing in front of the star.
“Here, we report on the discovery of a transiting planet around Pi Mensae, exactly the type of planet TESS was designed to detect,” write the authors in their preprint paper, which was uploaded to the arXiv server yesterday.
The planet circles the sun-like star Pi Mensae at a distance of about 7 million miles every 6.3 days, a distance Ricker described as “quite a bit too toasty” to be habitable by humanoids. The same star was already known to harbor a planet some 10 times as massive as Jupiter with a six-year orbit. That leaves that star with two planets — one too hot and one too cold.
Only a day later they unveiled another possible planet, a so-called “hot earth,” that circles a nearby small dim red dwarf star known as HS 3844 in an incredibly tight orbit only about a million miles from its sun.
Pi Mensae, also known as HD 39091, is an unusually bright yellow subgiant (dwarf) star. This star is visible to the naked eye and is located nearly 60 light-years from Earth. Based on data gathered from July 25 to August 22, the TESS team has concluded that Pi Mensae c, as the newly discovered planet is called, is a super-Earth. It’s about 2.14 times Earth’s radius and 4.82 times Earth’s mass. Pi Mensae c is too close to its host star to support life. A single year on this planet lasts just 6.27 days.
This is the second planet to have been detected around Pi Mensae. Back in 2001, astronomers detected an monster planet in this system, Pi Mensae b, which is nearly 10 times the mass of Jupiter, and the largest planet known to astronomers. This planet is so big that its surface likely glows, leading some astronomers to think it’s more a brown dwarf, a kind of failed star, than a planet. It’s also in an eccentric, or highly elliptical, orbit, taking 5.7 years to revolve around its host star.
TESS is scheduled to collect five additional months of data from this system, allowing the team to improve its knowledge of Pi Mensae c and to search for additional transiting planets.
This is the first of what should be an amazing collection of TESS discoveries. The mission is supposed to last for two years, during which time 500,000 stars will be studied. If all goes according to expectations, the space telescope could uncover as many as 1,000 new exoplanets. Will one or two harbor advanced technology-centric life?
The Daily Galaxy via NASA and the New York Times
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