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Exoplanet Discoveries, discussion of the latest finds
TheAnt
post Jun 19 2016, 09:49 AM
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Some years ago we were given the impression that quite some stellar systems had hot Jupiters. That turned out to be an observational bias since such planets are easy to detect.
But such systems have been found again in quite a number in a study where HARPS were the main instrument though also Hubble and a few others were used.
It appear that in the open star cluster M67 about one out of twenty stellar systems have a hot Jupiter.


(Sorry for awakening this very old thread. But I were once asked by a moderator not to start to many new topics.)
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Explorer1
post Aug 13 2016, 06:58 AM
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A Proxima Centauri planet!? ohmy.gif
http://phys.org/news/2016-08-scientists-un...ike-planet.html
No official confirmation or denial, but an announcement set for the end of August (if true!).
Translated Der Spiegel article that has source: https://translate.google.ca/translate?hl=en...amp;prev=search

Just hype, or something more?
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Gerald
post Aug 13 2016, 07:46 AM
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Seems, they found a hint to a small deviation of Proxima Centauri's trajectory close to the limits of statistical evidence.
The press tends to make a sensation of exciting preliminary hypotheses. So, let's wait, how statistically significant the findings actually turn out to be.
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HSchirmer
post Aug 14 2016, 01:30 AM
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Just noticed that Der Spiegel and other online sources are reporting a pre-announcement about a
a terrestrial planet with liquid water around alpha centauri...

Anybody hearing anything?
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JRehling
post Aug 14 2016, 02:32 AM
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Google searches limited to the last week show several results; this is one:

http://phys.org/news/2016-08-scientists-un...ike-planet.html

It is Proxima Centauri that is the host star; Proxima Centauri is believed to be part of the Alpha Centauri system, but it is quite remote from the other two and it is not certain that they are gravitationally bound. However, their distance from us is nearly equal.

Any discovery like this would be very exciting, but I'm quite sure that at this point, the only thing anyone could say about liquid water would be speculation based on the amount of insolation a planet receives; actually detecting liquid water would be a much harder feat.

I should say that Kepler data indicate that very roughly 8% of red dwarfs have Earth-sized planets in their habitable zone and roughly 8% have a Super Earth in their habitable zone… obviously this depends on definitions of HZ and the size bounds used. With a looser definition, the sum of those probabilities plus Mars-sized planets might climb over 50%. Which is to say: Without making any observations of Proxima Centauri, one could already saw that there's a good chance of a terrestrial planet with temperatures that could permit liquid water. One might even say that it's probable for each red dwarf. (Although this packs a lot of uncertainty into the "could permit liquid water" and definition of "terrestrial planet.") Furthermore, it seems nearly certain that one of the four or so closest red dwarfs should have a planet that meets those loose definitions.

I'll be eager to hear more, though. Proxima Centauri is the absolute easiest star in the universe for follow-up science on its planetary system. It would be a nice bit of luck if a candidate "earthlike" planet were there.
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nprev
post Aug 14 2016, 07:41 AM
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MOD MODE: Merged topic created for this alleged Proxima planet into this topic. There is absolutely no way that liquid water could have possibly been detected on this purported planet via the espoused (ground-based) discovery method. Media reports are spinning rapidly out of control. The characterization 'Earth-like" is inherently misleading; "Earth-sized" is much more plausible and accurate.

Furthermore, this is the same team that 'discovered' Alpha Centauri Bb, which was subsequently not confirmed. All these points should produce some healthy skepticism.

Bottom line is that this story is extremely speculative at this point--and therefore of extremely questionable quality as subject matter for UMSF. Discussion will be allowed using reputably sourced information, but not obvious sensationalism as seems to be the case for this thus far. This thread will be closed immediately if the discussion does not meet Forum standards.

"Extraordinary claims require extraordinary evidence"- Sagan's Law


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A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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JRehling
post Aug 14 2016, 03:01 PM
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This is indeed a good time to invoke Sagan's Law.

The notion that Proxima Centauri might have a planet is not a wild one at all – in fact, it may be nearly certain that any given red dwarf have at least one planet. The remarkable claim is about how much it might be like Earth, and those words "might" and "like" are packed full of opportunities to be vague and say nothing meaningful.

Here are key statements from the Spiegel article:

• The research involved in this took place at the limit of what measurements technically feasible.
• The method used involved "variations in the motion of the star."

The second statement is ambiguous. The Doppler method that measures radial (towards or away from Earth) movement of the star has been one of the two most productive methods for discovering exoplanets. Another method – long-discussed, but never-yet successful – has been to look at how a star wobbles side-to-side. The Doppler method works equally well for stars that are far or near, whereas the wobble method would be more successful for close stars – and Proxima Centauri is the closest – than any other. The Doppler method is also blind to planets in orbits that we see face-on, whereas the wobble method would work just fine for those… if it works for any cases at all, which is not clear. Finding Earth-mass planets has been elusive even for the Doppler method, with the smallest so far confirmed having a mass of about 3.7 mass[Earth] with an uncertainty of about 0.7. When the uncertainty in one of the best cases is 0.7 mass[Earth], it gives you an idea of the hopelessness of determining that any subsequent discovery would be very close to 1.0 mass[Earth] without very large relative uncertainty.

The first statement is of paramount importance: If the results come at the limit of what is technically feasible, then they almost inherently contain uncertainty, which would mean that there could be doubt as to whether or not they detected a planet as opposed to noise, and if they did detect a planet, even if it happened to be very much Earth-sized and getting Earth-like amounts of sunlight, the measurements would have too large of an error for us to be confident about the nature of the planet yet.

Given what we know in general about exoplanet occurrence, it would be surprising if Proxima Centauri didn't have some planets smaller than Neptune orbiting it, and it wouldn't be surprising if it had one about the size of Earth and getting about that much sunlight… but "not surprising" is a long way from confirmed.
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Explorer1
post Aug 14 2016, 04:18 PM
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Presumably they wouldn't have published the article if they knew they would be embarrassed by another false positive, right? The lack of flat denial from ESO also makes me anticipate that there really will be some announcement by the end of the month. Then we'll see where the chips fall, and the next step of the scientific method (attempts to replicate/confirm results) can be put in practice.
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Gerald
post Aug 14 2016, 11:12 PM
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Pale Red Dot has submitted a paper for peer review, and "Our paper has got positive referee reports!"
But at the same time "#PaleRedDot team says the Proxima Centauri planet report in @DerSPIEGEL didn't come from them."

From a tv channel:
QUOTE
." ESO-Sprecher Richard Hook erklärte jedoch zu dem angeblichen Sensationsfund, die Angaben basierten offenbar "größtenteils auf Gerüchten". Er könne den Inhalt des "Spiegel"-Berichts "nicht bestätigen". Die Ergebnisse der Suche nach einem möglichen Planeten bei Proxima Centauri würden "zur rechten Zeit bekanntgegeben", betonte Hook.

ESO-speaker Richard Hook, however, explained regarding the presumed sensational findings, the statements are obviously based "mostly on rumors". He "can't confirm" the contents of the "Spiegel" report. The results of the search for a possible planet near Proxima Centauri will be "reported in due time", emphasized Hook.
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nprev
post Aug 14 2016, 11:35 PM
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Thanks, Gerald. That's the kind of clarifying information that's needed concerning this story at this point.


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alphasam
post Aug 18 2016, 07:09 PM
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I'll just leave this here cool.gif

From BBC The Sky at Night presenter Chris Lintott;
https://twitter.com/chrislintott/status/766171247256412160


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JRehling
post Aug 19 2016, 06:23 PM
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Der Spiegel has published a new article that almost looks like the previous rumor-level article but with slightly less hedging:

http://www.spiegel.de/international/zeitge...-a-1107983.html

It'll be nice to have absolute confirmation that Proxima Centauri has planets but, to recap, it is somewhere between expected and very likely for any given red dwarf to have planets, and because they tend to have small planets, it is more or less expected for it to have a planet that's roughly earth-sized.

What would be nice to know is what uncertainty exists concerning any such detection. If the result is a detection with an estimated radius between 0.5 and 2.5 Earth radii, and/or similar uncertainty regarding its illumination, that's not going to mean much.

It would also be great, and surprising, if Proxima Centauri's planetary plane is aligned such that we see its planets transit, but there's no indication that this is going to be part of the announcement.

If Der Spiegel is accurate, we'll know within a couple of weeks what the team has found.
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alphasam
post Aug 22 2016, 02:14 PM
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There will be a press conference at ESO headquarters this Wednesday at 1pm CET, 7am EDT.
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TheAnt
post Aug 23 2016, 06:26 PM
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Hmm, if Der Spiegel is to believed, it is now claimed that the source was from the PaleRedDot team after all.
Lets see about this ESO announcement tomorrow. =)
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Gerald
post Aug 24 2016, 11:46 AM
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ESO on twitter:
QUOTE
Dear friends we will be making an announcement today at 19:00 CEST. Please stay tuned until then
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