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Weird Neptune-like exoplanet may have water clouds

rod

Oct 22, 2019
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Near the end of this report, "Despite orbiting closely to its star, TOI-1231 b has a relatively cool atmosphere of 140 degrees Fahrenheit (60 degrees Celsius). While that's more than double Earth's average temperature, Burt said TOI-1231 b is "positively frigid" compared with most transiting planets, such as "hot Jupiters," which typically reach scorching temperatures in the hundreds or thousands of degrees Fahrenheit or Celsius."

Another report on TOI-1231 b, https://phys.org/news/2021-06-scientists-exoplanet-atmosphere-ripe.html

My observation. Something important to note about exoplanets discovered and comparison with our solar system (phys.org report). "One of the most intriguing results of the last two decades of exoplanet science is that, thus far, none of the new planetary systems we've discovered look anything like our own solar system," said Burt. "They're full of planets between the size of Earth and Neptune on orbits much shorter than Mercury's, so we don't have any local examples to compare them to. This new planet we've discovered is still weird—but it's one step closer to being somewhat like our neighborhood planets."

Research paper, TOI-1231 b: A Temperate, Neptune-Sized Planet Transiting the Nearby M3 Dwarf NLTT 24399, https://arxiv.org/abs/2105.08077, 08-June-2021.
 
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rod

Oct 22, 2019
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Some system stats here, http://exoplanet.eu/catalog/toi-1231_b/

The host stars is listed at 0.485 solar masses. Using canonical dust/gas protoplanetary disk masses, the dust mass initially about 16 earth masses (10^-4 Mstar) and dust+gas total about 1600 earth masses in a protoplanetary disk when the host star was a proto-star assumed to evolve into this system.
 

Catastrophe

The devil is in the detail
Rod, you are the expert here imo on exopanets. If I may ask you a question, please, relevant to this thread: Is the deficiency in finding Earth size exoplanets further from their star due to the fact that the further away they are, the more difficult they are to see? I can see that smaller exoplanets further away will not receive a lot of light. Is it similar to the difficulties we had with TNOs etcetera? Would more distant exoplanets be more difficult to see crossing the star's disc? Maybe a question of orbital inclination?

Cat :) :)
 
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Jun 1, 2020
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The low temperature of this star, ~ 3550K, would likely limit how the atmosphere would get ionized and ejected. This puts the weak peak in radiation into the IR band. The near UV energy (400 nm) is < 2% that of the Sun.

The report also seems to be saying that TESS, with its limited time schedule, is limited in detecting fast period planets. The range has a mean of only ~ 14 days, though about 36 days seems possible. This isn't going to catch many Earth-like planets, if I understand what is being stated.
 
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rod

Oct 22, 2019
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Cat, your post #4 question and Helio post #5. You and Helio are on the right track it seems. Using this exoplanet site, http://exoplanet.eu/catalog/ I ran a MS SQL query selecting for exoplanets with masses <=3 earth masses. 65 returned with that property in my database. Almost all are detected by primary transit method indicating the exoplanet passed in front of host star and caused dimming. A few others were radial velocity and microlensing. 148 exoplanets are imaged but these are large bodies and farther away from their parent stars. The bulk of detection types are primary transit and radial velocity (4374 listed with these detection types). The 65 I found using the selection criteria, average orbital period is 9.6 days, min is 0.19 day period, and max is close to 47 days. All orbit very close to the parent star.

Using this site, https://exoplanetarchive.ipac.caltech.edu/index.html

I found 87 exoplanets with the mass selection I used. All have short periods, 62 days or less but one. PSR B0329+54 b with a period 10,140 days discovered by pulsar timing method. Its distance is 10.26 au from the pulsar and considered 1.97 earth masses.
 
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rod

Oct 22, 2019
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FYI. The .eu site updated today showing 4776 confirmed exoplanets. I did another query using <= 2 earth radii size (many have no mass property or null field for mass). 1311 exoplanets reported for duty. Orbital periods tightly packed too from 0.09 day to 757 days. a min 0.0034 au to 1.98 au. The phys.org report comments in post #2 make good sense about our solar system when I look at the exoplanet sites using MS SQL queries for low mass or small earth radii sizes and also very large masses, >= 1.1 Mjup size.
 
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Jun 26, 2021
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Thanks for reminding us how much the James Webb telescope cost for no reason. Constant reminders of cost, no matter what the benefits may be, are like "failure counters" that turn the public against such investments.
 

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