Two NASA interns and a team of amateur astronomers have discovered a new exoplanet roughly twice the size of Earth while gleaning through data captured by the U.S. space agency’s now-defunct Kepler space telescope.
Although the so-called “Super Earth” was first spotted by the “citizen scientists,” using information gathered by the Kepler space telescope during Campaign 4 of its extended K2 “Second Light” mission back in 2015, the data was discarded as unreliable due to issues with two of Kepler’s reaction wheels.
The same team analyzed the Campaign 4 data a second time and uploaded the re-processed information on Exoplanet Explorers – a new Zooniverse project open to public searches of Kepler’s K2 observations to locate new transiting planets – in 2017.
To cut a long story short, mistakes were made but follow-up observations, using data from the Keck Observatory in Hawaii, NASA’s Infrared Telescope – also in Hawaii, the agency’s Spitzer Space Telescope, and European Space Agency’s (ESA’s) Gaia space observatory, allowed the team to confirm the existence of K2-288Bb at the 233rd American Astronomical Society meeting in Seattle on January 7, 2019.
— Geert Barentsen (@GeertHub) January 7, 2019
“It’s a very exciting discovery due to how it was found, its temperate orbit and because planets of this size seem to be relatively uncommon,” said Adina Feinstein, a graduate student at the University of Chicago, Illinois, and the lead author of the study paper due to be published in The Astronomical Journal.
“It took the keen eyes of citizen scientists to make this extremely valuable find and point us to it,” Feinstein said.
Officially known as K2-288Bb, the exoplanet is possibly a rocky, or a gas-rich planet along the lines of Neptune.
It is located in the habitable zone, also known as “Goldilocks’ zone,” of a binary star system of the same name minus the suffix “b” in the constellation Taurus some 226 lightyears away from Earth.
The binary stellar system K2-288B, which K2-288Bb is a part of, contains two dim stars about 5.1 billion miles (8.2 billion kilometers) apart.
The larger and brighter of the two stars is about half the mass and size of our own Sun, while its stellar companion is about one-third of our Sun’s mass and girth.
However, it’s the lesser of the two stars that K2-288Bb orbits once every 31.3 Earth-days.
Simply put, an exoplanet is a planet that does not orbit our Sun but belongs to a different planetary system and orbits the star (sun) of that particular system.
They are also referred to as extrasolar planets; aptly so because they’re not part of our Solar System.
An exoplanet is named after the star of the system to which it belongs with a lower case letter added to the name as a suffix.
The first exoplanet discovered in the system gets the suffix ‘b’, with subsequent discoveries getting the letters c, d, e, and so forth, in the order they are found.
That is why the new exoplanet is named K2-288Bb – the ‘b’ at the end being the suffix for the first planet discovered in the stellar system K2-288B.
To give another example, TRAPPIST-1, an ultra-cool dwarf star in the constellation Aquarius, 39 light-years away from the Earth, has ten known exoplanets
Hence, based on the aforementioned naming methodology, the seven latest discoveries, starting from the planet closest to the star, are named TRAPPIST-1b, TRAPPIST-1c, TRAPPIST-1d, TRAPPIST-1e, TRAPPIST-1f, TRAPPIST-1g, and TRAPPIST-1h.
The letter ‘a’ by default goes to the parent star, though not shown with the name.
Habitable Zone (Goldilocks’ Zone)
An planet or exoplanet is said to be in the habitable zone of a planetary system when it is orbiting at an ideal distance from the system’s star/sun to potentially support life of any kind – not too close to the star to be too hot to support water formation, neither too far for water to be in a permanent freeze.
Kepler Space Observatory
Named after the astronomer, Johannes Kepler, the Kepler space observatory had been in an “Earth-trailing heliocentric orbit” ever since its launch in March 2009 as part of NASA’s program to discover Earth-sized exoplanets.
After nine years of service to science and space research, Kepler was decommissioned by the space agency on October 30, 2018.
The spacecraft was designed to scan an area of the galaxy in the vicinity of our own solar system to identify Earth-like exoplanets in and around the ‘habitable zones’ of their planetary systems.
Equipped with a photometer that continuously monitored the brightness of over 145,000 main sequence stars in a fixed field of view, Kepler beamed the collected data back to Earth for analysis.
The method involved detecting the periodic dimming which happens when exoplanets cross in front of their host star – similar to the Eclipse concept.
Due to noise interference in the data from the stars as well as the spacecraft, the mission was supposed to be extended till 2016 in order to achieve all mission targets.
However, built to endure the harsh space conditions for a maximum of 3.5 years, Kepler ran into trouble on July 14, 2012, when one of the four reaction wheels of the craft stopped turning.
Incident-free functioning of the three remaining reaction wheels was now critical to the completion of the mission but fate would have it differently.
On May 11, 2013, the continuation of the mission was seriously jeopardized when a second reaction wheel stopped working.
NASA failed in its attempt to fix the two out-of-commission reaction wheels, publicly throwing in the towel on August 15, 2013, with an announcement to the effect.
The agency then appealed to the space science community for alternative plans for continuing the search for exoplanets using the two working reaction wheels and thrusters.
The K2 “Second Light” proposal, which involved using the limited capabilities of the handicapped Kepler to track habitable planets around smaller and dimmer red dwarfs, was made in Nov 2013, getting NASA’s official nod in May 2014.
Since then until its demise, the space telescope’s had surveyed and cataloged hundreds of new planetary candidates.