Gaia Exoplanet News and Results

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Gaia Exoplanet News and Results

Post by Sirius_Alpha on 9th February 2017, 4:16 pm

Gaia has detected transits of WASP-19b and WASP-98b
http://sci.esa.int/gaia/58784-exoplanets/


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Re: Gaia Exoplanet News and Results

Post by Lazarus on 9th February 2017, 5:32 pm

Good spot there. Looking forward to seeing this thread grow longer!
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Re: Gaia Exoplanet News and Results

Post by Sirius_Alpha on 7th December 2017, 5:14 pm

Gaia mission extended through 2020.
http://sci.esa.int/director-desk/59839-green-light-for-continued-operations-of-esa-science-missions/

The lifetime of Gaia, ESA's billion star surveyor, was extended by eighteen months, from 25 July 2019 to 31 December 2020. This is the first time that Gaia, which was launched in 2013 and originally funded for a five-year mission, has been subject to the extension process.

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Re: Gaia Exoplanet News and Results

Post by Sirius_Alpha on 14th August 2018, 8:27 pm

Revised Exoplanet Radii and Habitability Using Gaia Data Release 2
https://arxiv.org/abs/1808.04533

Accurate stellar properties are crucial for determining exoplanet characteristics. Gaia DR2 presents revised distances, luminosities, and radii for 1.6 billion stars. Here, we report the calculation of revised radii and densities for 320 exoplanets using this data and present updated calculations of the incident flux received by 690 known exoplanets. This allows the likelihood that those planets orbit in the habitable zone of their host stars to be reassessed. As a result of this analysis, three planets can be added to the catalogue of potentially habitable worlds: HIP~67537~b, HD~148156~b, and HD~106720~b. In addition, the changed parameterisation of BD~+49~898 means that its planet, BD~+49~898~b, now receives an incident flux that places it outside the optimistic habitable zone region, as defined by \citep{Kopparapu2013,Kopparapu2014}. We find that use of the new \textit{Gaia} data results in a mean increase in calculated exoplanet radius of 3.76\%. Previously, CoRoT-3 b had been reported as having the highest density of all known exoplanets. Here, we use updated information to revise the calculated density of CoRoT-3~b from 26.4gcm−3 to 17.32.9gcm−3. We also report the densest exoplanet in our dataset, KELT-1~b, with a density of 23.74.0gcm−3. Overall, our results highlight the importance of ensuring the the parameterisation of known exoplanets be revisited whenever significant improvements are made to the precision of the stellar parameters upon which they are based.

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Re: Gaia Exoplanet News and Results

Post by Edasich on 15th August 2018, 9:46 am

According to this study HATS-12 b turns out a high-density planet more than twice the mass of Jupiter but with nearly Neptune-size radius. Possible??
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Re: Gaia Exoplanet News and Results

Post by tommi59 on 15th August 2018, 10:53 am

No envelope? rocky?
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Re: Gaia Exoplanet News and Results

Post by Lazarus on 15th August 2018, 1:21 pm

From the paper:
It is important to note that HATS-12s Gaia luminosity decreased to 12% of its previous value, so it is likely that the mass of HATS-12, and mass and density of HATS-12 b, also decreased

Using a nave extrapolation from the mass-luminosity relationship I get a revised mass of 1.7 Jupiter masses, which would still be a rather unusual planet. It probably warrants a full reanalysis to do it properly. Furthermore, Gaia DR2 stellar properties are rather preliminary so this is unlikely to be the last word on things. Gaia DR3 will probably revise everything all over again...
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Re: Gaia Exoplanet News and Results

Post by Sirius_Alpha on 1st September 2018, 12:05 pm

A five-year extension could increase the total number of detected planets from ~10,000 to ~70,000.
https://twitter.com/EricMamajek/status/1034696891248857089

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Re: Gaia Exoplanet News and Results

Post by Daniel on 14th November 2018, 11:54 am

Sirius_Alpha wrote:A five-year extension could increase the total number of detected planets from ~10,000 to ~70,000.
https://twitter.com/EricMamajek/status/1034696891248857089

it's getting there on a 10 years mission, GAIA Mission been extended at least until the end of 2022, the mission was extended before until the end of 2020 wich means 6.5 years mission plus two extra years now will be 8.5 years, which means more planet detections. Very Happy

http://sci.esa.int/director-desk/60943-extended-life-for-esas-science-missions/
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Re: Gaia Exoplanet News and Results

Post by Sirius_Alpha on 25th November 2018, 9:41 pm

Stellar and substellar companions of nearby stars from Gaia DR2 - Binarity from proper motion anomaly of stars within 50 pc
https://arxiv.org/abs/1811.08902

The census of stellar and substellar companions of nearby stars is largely incomplete, in particular towards the low mass brown dwarf and long-period exoplanets. It is however of fundamental importance for stellar and planetary formation and evolution mechanisms. We aim at characterizing the presence of physical companions of stellar and substellar mass orbiting nearby stars. Orbiting secondary bodies influence the proper motion (PM) of their parent star. Using the Hipparcos (Hip) and Gaia DR2 (GDR2) catalogs, we determine the long-term PM of each star. We then search for a proper motion anomaly (PMa) between the long-term PM and the GDR2 (or Hip) measurements, indicative of the presence of a secondary object. We present a catalog of the PMa of 6741 nearby stars located within 50 pc. A fraction of ~40% of these objects presents a PMa at a level of more than 2σ, and ~30% at more than 3σ. We present a few illustrations of the PMa analysis. We set upper limits of 0.1 - 0.2 MJup to potential planets of Proxima between 1 and 10 au and 2.5 MJup on any stable orbit. We confirm that Proxima is gravitationally bound to alpha Cen. We recover the masses of the known companions of eps Eri, eps Ind, Ross 614, GJ 229, tau Boo and beta Pic. We also detect a possible long-period planet of a few jovian masses orbiting tau Ceti. The combination of the GDR2 with Hipparcos and the very high accuracy of the derived PMa already enables to set valuable constraints on the binarity of nearby objects. The detection of tangential velocity anomalies at a level of σ(dVtan) = 1.1 m/s per parsec of distance is already possible with the GDR2. This opens the possibility to identify long period orbital companions otherwise inaccessible. The complementarity of Gaia, radial velocity and transit techniques already appears as remarkably powerful.

Emphasis mine.

Reading through the paper and summarizing the results:

The planet orbiting Proxima Centauri is too low in mass and close to the star to produce a large enough stellar reflex motion to be detectable. Gaia data in DR2 excludes the presence of planets above 0.2 Jupiter-masses out to 10 AU (~hundred-year orbits), as well as excluding planets above 0.4 Jupiter-massses out to 50 AU (~thousand year orbits). No planet of mass greater than 2.5 Jupiter-masses exists around this star out to the largest orbit possible for a planet to remain in a stable orbit (1700 AU).

For Barnard's Star, a hint (2σ) of a velocity anomaly is observed, which could be explained by a Jupiter-mass planet in a 1-20 AU orbit, or a 1.5 Jupiter-mass planet in a 20-100 AU orbit. The super-Earth that was announced orbiting the star earlier this month is not expected to produce a detectable stellar reflex motion.

For Ross 128, a marginally significant velocity anomaly is observed which could be explained by a Saturn-mass planet in a 1-10 AU orbit. Jupiter-mass planets within 30 AU are ruled out by the data. The reflex motion of the known low-mass planet around this star is not expected to be detectable with Gaia.

For Tau Ceti, a significant velocity anomaly is observed. Unfortunately Tau Ceti is so bright that the Gaia data for it is not of very high quality. Nevertheless, the observed velocity anomaly could be explained by a Jupiter analogue at 5 AU. Planets more massive than 3 Jupiter-masses are ruled out between 3 and 30 AU from the star. If this planet is real, it will be securely confirmed by further Gaia data, and will boost Tau Ceti to a five-planet system.

For Epsilon Indi, a significant velocity acceleration is observe by Gaia, and is compatible with the recently announced long-period gas giant planet orbiting this star.

For Kapteyn's Star, both reported planets are too low in mass and too close to the star to produce a detectable reflex motion. Gaia data excludes the presence of any planet more massive than Saturn between 1.5 and 10 AU.

For AX Microscopii, there is a significant velocity anomaly consistent with a giant planet with a mass of 0.5 - 2.5 Jupiter-masses in an orbit beyond 3 AU from the star.

LAWD 37 is a nearby white dwarf with a significant velocity anomaly from Gaia data. A 1-5 Jupiter-mass planet in a 3-100 AU orbit would explain the observed signal. Based on the proper motion of this star, it is expected to produce nine microlensing events through to 2026, perhaps enabling the direct detection of this planet.

HD 20794 has three known terrestrial planets in short orbital periods, with evidence of three more low-mass planets at longer periods. A significant velocity acceleration is observed by Gaia at this star, which would correspond to the presence of a 2 - 8 Jupiter-mass planet in a 3-30 AU orbit. The presence of a long-period gas giant planet with a series of inner low-mass planets would make HD 20794 a very promising analogue of the Solar System.

A possible velocity anomaly is observed for Fomalhaut B (TW PsA), but given the multiplicity of the stellar system, it's not clear if this corresponds to the gravitational influence of the primary star or an orbiting companion.

For 51 Pegasi, a strong velocity acceleration is observed, indicating the presence of a massive companion. It would have to be something other than the famous hot Jupiter discovered around this star, as the orbital period is too small for this planet to produce a detectable signal. They propose that a 6 Jupiter-mass planet in 3 AU orbit, up to a brown dwarf of several tens of Jupiter-masses in a >100 AU orbit could explain this.

Lastly, they detect the astrometric signal of the known planet orbiting Beta Pictoris.

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Re: Gaia Exoplanet News and Results

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