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posted by martyb on Sunday January 20 2019, @07:39AM   Printer-friendly [Skip to comment(s)]
from the that's-no-moon dept.

The first suspected exomoon may remain hidden for another decade

A good exomoon is hard to find. Proving that the first purported moon around an exoplanet actually exists could take up to a decade, its discoverers say.

"We're running into some difficult problems in terms of confirming the presence of this thing," said astronomer Alex Teachey of Columbia University at a meeting of the American Astronomical Society on January 10.

[...] That uncertainty is partly because the purported moon seems to be about the size of Neptune, much larger than moon formation theories predict. And the researchers can't rule out that the evidence of the moon isn't actually evidence of a second planet. "We're trying to be very careful about not calling this a discovery, that we've got this beyond a shadow of a doubt," Teachey said.

[...] Ground-based telescopes are trying to confirm if the object is a moon or a second planet based on the object's gravitational tugs on the known planet. That's a much slower process than looking for dips in light from exoplanets and exomoons passing in front of their stars, which is what the Hubble and Kepler data reveal, and could take five to 10 years, Teachey says.

Headline News: Object Not Found.

Previously: First Exo-Moon Discovered?
First Known Exomoon May Have Been Detected: Kepler 1625b i
New Evidence Supports Existence of Neptune-Sized Exomoon Orbiting Kepler-1625b


Original Submission

Related Stories

First Exo-Moon Discovered? 8 comments

New Scientist, on authority of NASA's Jet Propulsion Laboratory, reports that the first moon outside of our solar system may have been discovered.

It is not yet clear what double object MOA-2011-BLG-262 is: it may be a rogue planet with a massive moon about 1800 light years from Earth, or a faint star (brown or red dwarf) with a Neptune-sized planet much further away.

The discovery was made by telescopes in New Zealand and Tasmania during a micro-lensing event in 2011. Since the micro-lensing event is over and we don't know the distance of the double object, we can not distinguish between both possibilities.

(The discovery was published late 2013, but it is making mainstream news now.)

First Known Exomoon May Have Been Detected: Kepler 1625b i 1 comment

The first satellite orbiting an exoplanet may have been discovered:

A team of astronomers has potentially discovered the first known moon beyond the Solar System. If confirmed, the "exomoon" is likely to be about the size and mass of Neptune, and circles a planet the size of Jupiter but with 10 times the mass.

The signal was detected by Nasa's Kepler Space Telescope; astronomers now plan to carry out follow-up observations with Hubble in October. A paper about the candidate moon is published on the Arxiv pre-print site.

[...] The Kepler telescope hunts for planets by looking for tiny dips in the brightness of a star when a planet crosses in front - known as a transit. To search for exomoons, researchers are looking for a dimming of starlight before and after the planet causes its dip in light. The promising signal was observed during three transits - fewer than the astronomers would like to have in order to confidently announce a discovery.

The host star, Kepler-1625, is about 4,000 light years away. The potential exomoon, Kepler 1625b i, has been nicknamed "Nept-moon".

Also at ScienceNews.

The Hunt for Exomoons with Kepler (please update your site).


Original Submission

New Evidence Supports Existence of Neptune-Sized Exomoon Orbiting Kepler-1625b 9 comments

Hubble finds compelling evidence for a moon outside the Solar System

Using the NASA/ESA Hubble Space Telescope and older data from the Kepler Space Telescope two astronomers have found the first compelling evidence for a moon outside our own Solar System. The data indicate an exomoon the size of Neptune, in a stellar system 8000 light-years from Earth. The new results are presented in the journal Science Advances.

[...] In 2017 NASA's Kepler Space Telescope detected hints of an exomoon orbiting the planet Kepler-1625b. Now, two scientists from Columbia University in New York (USA) have used the incomparable capabilities of the NASA/ESA Hubble Space Telescope to study the star Kepler-1625, 8000 light-years away, and its planet in more detail. The new observations made with Hubble show compelling evidence for a large exomoon orbiting the only known planet of Kepler-1625. If confirmed, this would be the first discovery of a moon outside our Solar System.

The candidate moon, with the designation Kepler-1625b-i, is unusual because of its large size; it is comparable in diameter to the planet Neptune. Such gargantuan moons are unknown in our own Solar System.

Other sources put Kepler-1625 at around 4,000 light years away.

Discoveries like this are why we could use as many identical better-than-Hubble space telescopes as we can build and launch.

Also at Sky & Telescope, Cosmos Magazine, The Verge, Axios, NPR, CNN.

Evidence for a large exomoon orbiting Kepler-1625b (open, DOI: 10.1126/sciadv.aav1784) (DX)

Previously: First Exo-Moon Discovered?
First Known Exomoon May Have Been Detected: Kepler 1625b i


Original Submission

Another Neptune-Like Exomoon Candidate Reported (Kepler-1708 b-i) 9 comments

Astronomers may have found a second Neptune-size exomoon hidden in the retired Kepler space telescope's data

Despite an explosion of exoplanet discoveries since the 1990s, astronomers have not confirmed the discovery of a single exomoon. In fact, only around a dozen exomoon candidates have been put forward up to now.

In 2018, David Kipping (Columbia University) and Alex Teachey (now at Academia Sinica, Taiwan) were the first, tentatively reporting a possible Neptune-radius moon about 7,800 light-years from Earth: Kepler-1625 b-i. Now, the astronomers and other colleagues have announced the discovery of another exomoon, published January 14th in Nature Astronomy. However, just as before, they urge both caution and the need for further observations.

The putative exomoon, designated Kepler-1708 b-i, was found 5,700 light-years away, orbiting a Jupiter-size planet around a star similar to the Sun. The planet is on a Mars-like orbit, at about 1.6 astronomical units (a.u.). Its moon orbits about 12 planetary radii away, similar to Europa's distance from Jupiter. Unlike Europa, though, Kepler-1708 b-i is huge, about 2.5 times Earth's size. This means the moon would be unlike any satellite in our solar system.

Journal Reference:
David Kipping, Steve Bryson, Chris Burke, et al. An exomoon survey of 70 cool giant exoplanets and the new candidate Kepler-1708 b-i [open], Nature Astronomy (DOI: 10.1038/s41550-021-01539-1)

Yet another observation to add onto JWST's schedule.

Also at Scientific American.

Previously: First Exo-Moon Discovered?
First Known Exomoon May Have Been Detected: Kepler 1625b i
New Evidence Supports Existence of Neptune-Sized Exomoon Orbiting Kepler-1625b
Exomoon Confirmation Remains Elusive


Original Submission

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  • (Score: 2) by bzipitidoo on Sunday January 20 2019, @04:57PM (8 children)

    by bzipitidoo (4388) Subscriber Badge on Sunday January 20 2019, @04:57PM (#789075) Journal

    One of the fun things about a discovery like this is all the debate it provokes. So, a moon orbits a planet, not a star. That's clear enough.

    But where is the line between moon and planet, and double planet? I understand the working criteria is that if the barycenter is within the larger body, then it is a moon and a planet, otherwise it is a double planet. So, Pluto and Charon are double dwarf planets? But that has some serious problems. It doesn't account for changes. The Moon is receding from the Earth, and in a few billion years, the Earth-Moon barycenter will have migrated outside the Earth. I think a better definition is that if the smaller object would have to be outside the Hill Sphere to put the barycenter outside the larger body, then it is a moon. Otherwise it is a double planet.

    Also, we were quite happy to let objects too small to round out be called moons, but planets, even dwarf planets, have to be round.

    • (Score: 2) by takyon on Sunday January 20 2019, @05:41PM (7 children)

      by takyon (881) <{takyon} {at} {soylentnews.org}> on Sunday January 20 2019, @05:41PM (#789083) Journal

      It's a problem that we want to have. Just as we went from a handful of known exoplanets to thousands, revealing unknown types of planets, we will eventually go from 0 known exomoons (a handful of candidates) to many confirmations. And we'll get to see new types of moons and planetary systems that were unimaginable (or at least confined to the realm of imagination).

      I am hopeful that there is a Planet Nine (fifth gas giant) in our solar system since it would give us an opportunity to closely study a new batch of moons. For all of the diversity of moons in our solar system, we have none that are as large as Mars, Earth, or Neptune, only one with a dense atmosphere, etc.

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      • (Score: 2) by PartTimeZombie on Sunday January 20 2019, @10:10PM (6 children)

        by PartTimeZombie (4827) on Sunday January 20 2019, @10:10PM (#789155)

        I like to think of Astronomy as humanity peering through the keyhole of a huge warehouse and trying to figure out what it contains.

        Our star and solar system is the only one we can really observe, so we have to base our theories on a sample of one, when there are hundreds of billions of stars in our galaxy.

        I was kind of hoping planet nine turns out to be a massive rocky world, of the super-Easrth type, just because that's a type of planet we know exists, but we don't have one. It could still have lots of moons of course.

        • (Score: 3, Informative) by takyon on Sunday January 20 2019, @10:42PM (5 children)

          by takyon (881) <{takyon} {at} {soylentnews.org}> on Sunday January 20 2019, @10:42PM (#789173) Journal

          A Planet Nine would have a huge gravitational sphere of influence due to being so far from the Sun. Larger than Jupiter's or Neptune's. Accordingly it could end up having more moons than Jupiter. On the other hand, because it would be further away from the Sun, objects should tend to be more dispersed. So it may have less moons because of that.

          We are missing super-Earths and mini-Neptunes. Obviously, a rocky surface would be a lot more interesting since it would be the closest example of a rocky body larger than Earth, and it could have life in a subsurface ocean that we could eventually reach (vs. a gas giant which probably doesn't have life and would be fatal for humans to explore).

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          • (Score: 2) by PartTimeZombie on Sunday January 20 2019, @10:48PM (1 child)

            by PartTimeZombie (4827) on Sunday January 20 2019, @10:48PM (#789176)

            All good points. Thanks.

            Can we just get on and go find it already?

          • (Score: 2) by bzipitidoo on Monday January 21 2019, @03:04AM (2 children)

            by bzipitidoo (4388) Subscriber Badge on Monday January 21 2019, @03:04AM (#789374) Journal

            I was thinking of a fun possibility for Planet 9. Suppose it's a double planet? And, that each one was about 3 Earth masses? Might be a bit harder to find that.

            • (Score: 2) by takyon on Monday January 21 2019, @04:55AM (1 child)

              by takyon (881) <{takyon} {at} {soylentnews.org}> on Monday January 21 2019, @04:55AM (#789402) Journal

              I don't see a large binary planet being split evenly like that. Works for some asteroid pairs, but multiple Earth masses?

              If two binary planet components were separated by a relatively long distance (like up to 1 AU), that could lower their brightness since they wouldn't appear as one object. It could also lower their temperature and the amount of infrared light given off, making them even harder to detect.

              There has been talk of a Mars-sized Planet Ten at the far edge of the Kuiper belt, or other such objects. Those may be easier to find than a hard mode Planet(s) Nine.

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              • (Score: 2) by bzipitidoo on Monday January 21 2019, @03:19PM

                by bzipitidoo (4388) Subscriber Badge on Monday January 21 2019, @03:19PM (#789608) Journal

                Well, I think a double planet is very unlikely, but it's still a fun thought.

                One thing about the simulations that show the existence of a Planet 9, is that by the chance of being the outermost of the giant planets, Neptune is awfully important, and the rest don't seem to much matter. But if there is a Mars sized Planet Ten in a 100 AU orbit, could that be more important to the orbital dynamics about Planet 9?

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