TESS finds the first two mini-Neptune exoplanets
In discovering three candidate exoplanets orbiting a nearby red dwarf star, the space telescope TESS has found the first two that are sized somewhere between the rocky Earth-sized planets and the larger Neptune-sized gas giants.
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. Due to its proximity to the star, planet b is an oven-hot world. Its equilibrium temperature — that is, the temperature based only on energy it receives from the star, which ignores additional warming effects from a possible atmosphere — is around 490 degrees Fahrenheit (254 degrees Celsius).
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.
All of the planets are expected to be tidally locked to the star, which means they only rotate once every orbit and keep the same side facing the star at all times, just as the Moon does in its orbit around Earth.
Planet c and d might best be described as mini-Neptunes, a type of planet not seen in our own solar system. The researchers hope further exploration of TOI 270 may help explain how two of these mini-Neptunes formed alongside a nearly Earth-size world.
The star is only 73 light years away.
Need I say that our level of knowledge about solar system formation is tiny at this point, and that any models any theorist creates should merely be seen as scratchpad first approximations, useful only in guiding future research and not to be taken too seriously.
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In discovering three candidate exoplanets orbiting a nearby red dwarf star, the space telescope TESS has found the first two that are sized somewhere between the rocky Earth-sized planets and the larger Neptune-sized gas giants.
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. Due to its proximity to the star, planet b is an oven-hot world. Its equilibrium temperature — that is, the temperature based only on energy it receives from the star, which ignores additional warming effects from a possible atmosphere — is around 490 degrees Fahrenheit (254 degrees Celsius).
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.
All of the planets are expected to be tidally locked to the star, which means they only rotate once every orbit and keep the same side facing the star at all times, just as the Moon does in its orbit around Earth.
Planet c and d might best be described as mini-Neptunes, a type of planet not seen in our own solar system. The researchers hope further exploration of TOI 270 may help explain how two of these mini-Neptunes formed alongside a nearly Earth-size world.
The star is only 73 light years away.
Need I say that our level of knowledge about solar system formation is tiny at this point, and that any models any theorist creates should merely be seen as scratchpad first approximations, useful only in guiding future research and not to be taken too seriously.
The support of my readers through the years has given me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Four years ago, just before the 2020 election I wrote that Joe Biden's mental health was suspect. Only in this year has the propaganda mainstream media decided to recognize that basic fact.
Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Even today NASA and Congress refuse to recognize this reality.
In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
Please consider supporting my work here at Behind the Black.
You can support me either by giving a one-time contribution or a regular subscription. There are five ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
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3. A Paypal Donation:
5. Donate by check, payable to Robert Zimmerman and mailed to
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c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above. And if you buy the books through the ebookit links, I get a larger cut and I get it sooner.
Assuming they’ve identified these exoplanets and their characteristics with any accuracy, those have got to be some pretty interesting places. A tidally locked gas giant well inside Mercury’s orbit has got to have some amazing stuff going on in that atmosphere. Would it sort itself into layers based on the solar input with certain gasses facing the sun and other gasses hiding in the shadow? Or is the insolation from that dwarf star so low that even at 0.05au it’s just not that dramatic?
Only 73 Light Years = Only 429 TRILLION miles : )
Close astronomically, but still a very, very, very, VERY long way away. Maybe one of our digital progeny will visit it in a millennia or so.
It’s fascinating how many of these hot gas giants we’ve found. Is this simply a case of selection bias due to our method of observation, or is there something about planetary system formation that we don’t understand?
Scott–
I rather think it’s both.
(I seem to recall watching a lecture on TESS recently wherein selection-bias was touched upon in some depth, if I can find it I’ll post it.)
Scott and Wayne: The answer is both. We don’t know enough, and we have a considerable selection bias.
Mr. Z.,
totally thinking out loud– we really can’t explain the formation of our own solar system, can we? I’m just arm-chair familiar with the theories, but we only really have a sample size of 1, ya know!?
That having been said, “we’re living in the future.” This is all amazing stuff.
— highly informative:
Initial Exoplanet Discoveries from TESS
Space Telescope Science Institute
January 2019
https://youtu.be/j91SQQiZdBY
1:18:39
(content starts about 20 minutes in)
” Dr. Scott Fleming will share several of the first exciting discoveries, plus detail about how the observatory is designed and how it compares to NASA’s Kepler/K2 mission. All of the data from TESS is available in the Barbara A. Mikulski Archive for Space Telescopes (MAST), which is based at the Space Telescope Science Institute.”