Phys.org had a good story on the reclassification of objects captured by the NASA’s Kepler Space Telescope once believed to be exoplanets. New evidence indicates three “exoplanets” – Kepler-854b, Kepler-840b, and Kepler-699b – are actually stars (hence, the NASA image above will need to be modified).
The article notes that the three objects are too large to be considered planets, being between two and four times the size of Jupiter. The results were part of a study from the Astronomical Journal. A fourth exoplanet, Kepler-747 b, might also be a star.
After updated information indicated Kepler-854b was about three times the size of Jupiter, one of the study authors said, “There’s no way the universe can make a planet of that size…It just doesn’t exist.”
While the team reviewed about 2,000 Kepler exoplanets to find these four questionable items, it is likely that more will be found in the future among other reported exoplanets. Fortunately, that still leaves us with plenty of real exoplanets to study.
Source/Credit: Nancy Grace Roman Space Telescope from NASA.
With all the excitement about the James Webb Space Telescope coming online shortly, we do not want to forget about another space telescope in development. NASA’s Nancy Grace Roman Space Telescope, expected to be launched in 2027, will be even more productive than the Hubble Space Telescope. NASA noted the new space telescope will be:
Providing the same crisp infrared resolution as Hubble over a field of view 200 times larger, Roman will conduct sweeping cosmic surveys that would take hundreds of years using Hubble. Roman will map stars, galaxies, and dark matter to explore the formation and evolution of large cosmic structures, like clusters and superclusters of galaxies, and investigate dark energy, which is thought to accelerate the expansion of the universe.
The Nancy Grace Roman Space Telescope will also have a Coronagraph Instrument that will be able to detect more exoplanets, including smaller, rocky exoplanets similar to Earth. By using the parent star’s reflected light on a larger exoplanet, this instrument will also allow astronomers to analyze the colors of the exoplanet’s atmosphere and learn more about the content of that atmosphere (complementing other studies of large exoplanets, one of which was noted here earlier). If successful, this technology could be refined further to one day help to detect oxygen, methane, and other elements/compounds in the atmosphere of distant, Earth-sized exoplanets.
Astronomer Vanessa Bailey from NASA’s Jet Propulsion Laboratory stated:
To image Earth-like planets, we’ll need 10,000 times better performance than today’s instruments provide…The Coronagraph Instrument will perform several hundred times better than current instruments, so we will be able to see Jupiter-like planets that are more than 100 million times fainter than their host stars.
The telescope is named after Nancy Grace Roman, who was NASA’s first chief astronomer and also known as the “Mother of Hubble” for her efforts in making the Hubble Space Telescope a reality. You can read more about her here.
Source/Credit: Artist’s image of WASP-121b from Engine House VFX.
It was not so long ago that we were questioning the very existence of exoplanets, and now we are measuring their dark-sides. MIT News has a story about a recent paper discussing the findings of astronomers observing an exoplanet approximately 850 light years from Earth. About twice the size of Jupiter and tidally-locked with its host star, the exoplanet has a very strange water cycle. The article states:
While on Earth, water cycles by first evaporating, then condensing into clouds, then raining out, on WASP-121b, the water cycle is far more intense: On the day side, the atoms that make up water are ripped apart at temperatures over 3,000 kelvins. These atoms are blown around to the night side, where colder temperatures allow hydrogen and oxygen atoms to recombine into water molecules, which then blow back to the day side, where the cycle starts again.
The article and paper go into many more details, yet I am most impressed with this level of observation already possible using a spectroscopic camera aboard NASA’s Hubble Space Telescope. With the James Webb Space Telescope soon to go online, we can only hope for more fascinating insights into distant exoplanets.
Source/Credit: A NASA composite image of Uranus taken from Voyager 2 and the Hubble Space Telescope.
In an earlier posting, I highlighted some scientific papers calling for a return to Neptune rather than Uranus, in part because of Neptune’s moon Triton. But what is the argument for a mission to Uranus? Below I highlight one of the papers submitted to the Planetary Science and Astrobiology Decadal Survey 2023-2032 arguing the merits of a NASA mission to Uranus.
The large moons of Uranus are possible ocean worlds that exhibit a variety of surface features, hinting at endogenic geologic activity in the recent past. These moons are rich in water ice, as well as carbon-bearing and likely nitrogen-bearing constituents, which represent some of the key components for life as we know it. However, our understanding of Uranus and its moons is severely limited by the absence of data collected by an orbiting spacecraft…
An orbiter would vastly improve our understanding of these possible ocean worlds and allow us to assess the nature of water and organics in the Uranian system, thereby improving our knowledge of these moons’ astrobiological potential. A Flagship mission to Uranus can be carried out with existing chemical propulsion technology by making use of a Jupiter gravity assist in the 2030 – 2034 timeframe, leading to a flight time of only ~11 years, arriving in the early to mid 2040’s (outlined in the Ice Giants Pre-Decadal Survey Mission Study Report: https://www.lpi.usra.edu/icegiants/mission_study/Full-Report.pdf).
The five large moons discussed in the paper are Miranda, Ariel, Umbriel, Titania, and Oberon. Titania and Oberon where the first to be discovered back in 1787, followed by the later discoveries of Ariel, Umbriel, and Miranda (in that order). Unlike the moons of other planets, the moons of Uranus are named after magical spirits in English literature.
All of these ocean worlds have gained greater interest as we learn about the dynamics of life on of our own planet. As noted in an article in the MIT Technology Review:
It was once thought the solar system was probably a barren wasteland apart from Earth. Rocky neighbors were too dry and cold like Mars, or too hot and hellish like Venus. The other planets were gas giants, and life on those worlds or their satellite moons was basically inconceivable. Earth seemed to be a miracle of a miracle.
But life isn’t that simple. We now know that life on Earth is able to thrive in even the harshest, most brutal environments, in super cold and super dry conditions, depths of unimaginable pressures, and without the need to use sunlight as a source of energy. At the same time, our cursory understanding of these obscure worlds has expanded tremendously.
We have plenty of worlds to explore in our own solar system as other scientists continue their search for exoplanets and exomoons. The only question now is which local worlds will we visit in our next round of space missions.
Source/Credit: Artist rendering of a candidate exoplanet orbiting Proxima Centauri from the ESO.
Earlier this month, astronomers utilizing the European Space Observatory’s (ESO) Very Large Telescope identified what appears to be a third exoplanet orbiting Proxima Centauri, the closest star to our solar system at about 4.2 light years away. The ESO press release shared the following details:
The newly discovered planet, named Proxima d, orbits Proxima Centauri at a distance of about four million kilometres, less than a tenth of Mercury’s distance from the Sun. It orbits between the star and the habitable zone — the area around a star where liquid water can exist at the surface of a planet — and takes just five days to complete one orbit around Proxima Centauri.
The star is already known to host two other planets: Proxima b, a planet with a mass comparable to that of Earth that orbits the star every 11 days and is within the habitable zone, and candidate Proxima c, which is on a longer five-year orbit around the star.
…At just a quarter of the mass of Earth, Proxima d is the lightest exoplanet ever measured using the radial velocity technique, surpassing a planet recently discovered in the L 98-59 planetary system. The technique works by picking up tiny wobbles in the motion of a star created by an orbiting planet’s gravitational pull. The effect of Proxima d’s gravity is so small that it only causes Proxima Centauri to move back and forth at around 40 centimetres per second (1.44 kilometres per hour).
It’s great to learn a little more about our nearest neighbor.
Our Awesome Universe 