Gaia Exoplanet News and Results

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

Good spot there. Looking forward to seeing this thread grow longer!

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

Quote :

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.

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

Quote :

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 17.3±2.9gcm−3. We also report the densest exoplanet in our dataset, KELT-1~b, with a density of 23.7±4.0gcm−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.

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??

No envelope? rocky?

From the paper:

Quote :

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 naïve 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...

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

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.

http://sci.esa.int/director-desk/60943-extended-life-for-esas-science-missions/

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

Quote :

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.

The Possible Astrometric Signature of a Planetary-mass Companion to the Nearby Young Star TW Piscis Austrini (Fomalhaut B): Constraints from Astrometry, Radial Velocities, and Direct Imaging
https://arxiv.org/abs/1910.02965

Quote :

We present constraints on the presence of substellar companions to the nearby (d∼7.6 pc), young (440±40 Myr) K4Ve star TW Piscis Austrini, the wide (∼0.3 pc) companion to the A4V star Fomalhaut. We combined absolute astrometry from Hipparcos and Gaia with literature radial velocity measurements and dedicated high-contrast imaging observations obtained with Keck/NIRC2 to achieve sensitivity to brown dwarf and planetary-mass companions (≳2 MJup) over many decades of orbital period (≲103 yr). The significant astrometric acceleration measured between the Hipparcos and Gaia catalogues, reported previously in the literature, cannot be explained by the orbital motion of TW PsA around the barycenter of the Fomalhaut triple system. Instead, we find that it is consistent with the reflex motion induced by an orbiting substellar companion. The combination of astrometry, radial velocities, and a deep L′ imaging dataset leads to a constraint on the companion mass of 1.2+0.7−0.6 MJup. However, the period of the companion is poorly constrained, with a highly multi-modal period posterior distribution due to aliasing with the 24.25 year baseline between Hipparcos and Gaia. If confirmed through continued astrometric or spectroscopic monitoring, or via direct detection, the companion to TW PsA would represent a choice target for detailed atmospheric characterization with high-contrast instruments on the upcoming James Webb Space Telescope and Wide Field Infrared Survey Telescope.

This was reported in the paper in the previous post.

Search for stellar companions of exoplanet host stars by exploring the second ESA-Gaia data release
https://academic.oup.com/mnras/article/490/4/5088/5622591

Lots of new stellar companions. A few interesting points:
- Kepler-25 (three confirmed planets) and KOI-1803 (two unconfirmed planets) turn out to be gravitationally bound to each other.
- Kepler-970 turns out to be the secondary star to the F2V star TYC 3125-219-1.
- K2-151 turns out to be the secondary star to HIP 6001.
- Several new WD companions to exoplanet hosting stars, doubling the number of such systems known, not counting eclipsing binary systems like DE CVn.
- Kepler-779b becomes the first known terrestrial planet to exist in a system with a white dwarf.

Belokurov et al. "Unresolved stellar companions with Gaia DR2 astrometry"
https://arxiv.org/abs/2003.05467

From the conclusion:

Quote :

Finally, we have explored the astrometric behaviour of exoplanetary hosts. Typically, only low-mass stars with massive planets on wide orbits have a chance of being perturbed enough to be detected by Gaia. It is therefore surprising to see a hint of an excess of hot jupiter hosts with small but measureable centroid perturbations. In these systems, the planets are too close to their hosts to perturb the star’s motion. We conclude therefore that, if real, this detection can be interpreted as a possible evidence for the presence of additional low-mass companions to massive hot jupiter hosts.

Determining the true mass of radial-velocity exoplanets with Gaia: 9 planet candidates in the brown-dwarf/stellar regime and 27 confirmed planets
https://arxiv.org/abs/2009.14164

Quote :

Mass is one of the most important parameters for determining the true nature of an astronomical object. Yet, many published exoplanets lack a measurement of their true mass, in particular those detected thanks to radial velocity (RV) variations of their host star. For those, only the minimum mass, or msini, is known, owing to the insensitivity of RVs to the inclination of the detected orbit compared to the plane-of-the-sky. The mass that is given in database is generally that of an assumed edge-on system (∼90∘), but many other inclinations are possible, even extreme values closer to 0∘ (face-on). In such case, the mass of the published object could be strongly underestimated by up to two orders of magnitude. In the present study, we use GASTON, a tool recently developed in Kiefer et al. (2019) & Kiefer (2019) to take advantage of the voluminous Gaia astrometric database, in order to constrain the inclination and true mass of several hundreds of published exoplanet candidates. We find 9 exoplanet candidates in the stellar or brown dwarf (BD) domain, among which 6 were never characterized. We show that 30 Ari B b, HD 141937 b, HD 148427 b, HD 6718 b, HIP 65891 b, and HD 16760 b have masses larger than 13.5 MJ at 3-σ. We also confirm the planetary nature of 27 exoplanets among which HD 10180 c, d and g. Studying the orbital periods, eccentricities and host-star metallicities in the BD domain, we found distributions with respect to true masses consistent with other publications. The distribution of orbital periods shows of a void of BD detections below ∼100 days, while eccentricity and metallicity distributions agree with a transition between BDs similar to planets and BDs similar to stars about 40-50 MJ.

Nice to see that it confirms the previous result for HD 16760.

Quick summary from skimming it...

The candidates with strong detections, unsurprisingly these turn out to be masses in the star/BD range (with the possible exception of one problematic candidate):

• 30 Ari Bb turns out to be a low-mass star, making 30 Ari a quintuple star system.
  
• HD 114762 b appears to be a star or a brown dwarf. 1σ range is above the BD/star boundary.
  
• HD 141937 b has a 3σ mass range that allows for it to be in the planetary domain, but looks more likely to be a brown dwarf.
  
• HD 148427 b is a star or a brown dwarf. 1σ range is above the BD/star boundary.
  
• HD 5388 b is a star or a brown dwarf. 1σ range straddles the BD/star boundary.
  
• HD 6718 b is a star or a brown dwarf. 1σ range straddles the BD/star boundary.
  
• HD 96127 b is problematic: MCMC didn't converge. Final mass range goes from planetary to stellar.
  
• HIP 65891 b turns out to be a low-mass star.
  

At least we still have Kepler-64 as evidence for planets in quadruple star systems...

The 3σ upper limit on the mass of HD 33636 b is 93.5 Jupiter masses, which appears incompatible with the previous mass determination of 140±11 by Bean et al. (2017). Potentially some hints of confusion between parallax and orbital motion.

The non-detections with 3σ upper limits below 13.5 Jupiter masses, 3σ upper limits in Jupiter masses in brackets:

• BD-06°1339 b (4.792)
  
• BD-08°2823 b (9.277)
  
• HD 10180 c (8.626), d (10.37), g (10.62)
  
• HD 125595 b (11.11)
  
• HD 154345 b (11.94) - as an upper limit I don't think this resolves the orbital motion vs stellar activity question.
  
• HD 175607 b (7.728)
  
• HD 176986 b (4.681), c (6.601)
  
• HD 179079 b (13.20)
  
• HD 181433 b (5.376), c (6.944), d (11.28)
  
• HD 215152 b (1.779), c (1.475), d (2.424), e (3.069)
  
• HD 215497 (4.999)
  
• HD 7199 b (11.45)
  
• HD 7924 b (6.476), c (5.546), d (4.934)
  
• HIP 57274 b (10.57)
  
• HD 40307 b (3.741), c (5.879), d (5.586)
  

Gaia discovers its first transiting planet at Gaia EDR3 3026325426682637824.
https://www.cosmos.esa.int/web/gaia/iow_20210330

TESS observations also flagged the planet as TIC 11755687.01, and PEPSI RV follow-up finds a mass of 1.1±0.1 M_J.

Quote :

More candidate transiting planets like this one are waiting for their detailed analysis. They will be published separately as public CU7 variability announcements that will be available for follow-up observations by the broad astronomical community.

Precise Masses and Orbits for Nine Radial Velocity Exoplanets
https://arxiv.org/abs/2109.10422

Quote :

We confirm the planetary nature of six companions: HD 29021 b ($4.47_{-0.65}^{+0.67}\Mjup$), HD 81041 b ($7.24_{-0.37}^{+1.0}\Mjup$), HD 87883 b ($6.31_{-0.32}^{+0.31}\Mjup$), HD 98649 b ($9.7_{-1.9}^{+2.3}\Mjup$), HD 106252 b ($10.00_{-0.73}^{+0.78}\Mjup$), and HD 171238 b ($8.8_{-1.3}^{+3.6}\Mjup$). We place one companion, HD 196067 b ($12.5_{-1.8}^{+2.5}\Mjup$) on the planet-brown dwarf boundary, and two companions in the low mass brown dwarf regime: HD 106515 Ab ($18.9_{-1.4}^{+1.5}\Mjup$), and HD 221420 b (${20.6}_{-1.6}^{+2.0}\Mjup$).

Sirius_Alpha wrote:

Gaia discovers its first transiting planet at Gaia EDR3 3026325426682637824.
https://www.cosmos.esa.int/web/gaia/iow_20210330

TESS observations also flagged the planet as TIC 11755687.01, and PEPSI RV follow-up finds a mass of 1.1±0.1 M_J.

Quote :

More candidate transiting planets like this one are waiting for their detailed analysis. They will be published separately as public CU7 variability announcements that will be available for follow-up observations by the broad astronomical community.

Here it is!

http://exoplanet.eu/catalog/2mass_j06023447-0034369_b/

More info about the host star here.

It has been published in January 2022 (after a rather long publication history dating back to January 2021) but no arXiv preview anywhere or any way to access full text. Yet it seems to contain very interesting piece of news.

Close substellar-mass companions in stellar wide binaries: discovery and characterization with APOGEE and Gaia DR2

Quote :

We present a search for close, unresolved companions in a subset of spatially resolved Gaia wide binaries containing main-sequence stars within 200 pc of the Sun, utilizing the APOGEE–Gaia Wide Binary Catalog. A catalogue of 37 wide binaries was created by selecting pairs of stars with nearly identical Gaia positions, parallaxes, and proper motions, and then confirming candidates to be gravitationally bound pairs using APOGEE radial velocities. We identify close, unresolved stellar and substellar candidate companions in these multiple systems using (1) the Gaia binary main sequence and (2) observed periodic radial velocity variations in APOGEE measurements due to the influence of a close substellar-mass companion. The studied wide binary pairs reveal a total of four stellar-mass close companions in four different wide binaries, and four substellar-mass close companion candidates in two wide binaries. The latter are therefore quadruple systems, with one substellar-mass companion orbiting each wide binary component in an S-type orbit. Taken at face value, these candidate systems represent an enhancement of an order of magnitude over the expected occurrence rate of ∼2 per cent of stars having substellar companions >2 M_Jup within ∼100-d orbits; we discuss implications and possible explanations for this result. Finally, we compare chemical differences between the components of the wide binaries and the components of the candidate higher-order systems and find that any chemical influence or correlation due to the presence of close companions to wide binary stars is not discernible.

Edasich wrote:

It has been published in January 2022 (after a rather long publication history dating back to January 2021) but no arXiv preview anywhere or any way to access full text. Yet it seems to contain very interesting piece of news.

Close substellar-mass companions in stellar wide binaries: discovery and characterization with APOGEE and Gaia DR2

Quote :

We present a search for close, unresolved companions in a subset of spatially resolved Gaia wide binaries containing main-sequence stars within 200 pc of the Sun, utilizing the APOGEE–Gaia Wide Binary Catalog. A catalogue of 37 wide binaries was created by selecting pairs of stars with nearly identical Gaia positions, parallaxes, and proper motions, and then confirming candidates to be gravitationally bound pairs using APOGEE radial velocities. We identify close, unresolved stellar and substellar candidate companions in these multiple systems using (1) the Gaia binary main sequence and (2) observed periodic radial velocity variations in APOGEE measurements due to the influence of a close substellar-mass companion. The studied wide binary pairs reveal a total of four stellar-mass close companions in four different wide binaries, and four substellar-mass close companion candidates in two wide binaries. The latter are therefore quadruple systems, with one substellar-mass companion orbiting each wide binary component in an S-type orbit. Taken at face value, these candidate systems represent an enhancement of an order of magnitude over the expected occurrence rate of ∼2 per cent of stars having substellar companions >2 M_Jup within ∼100-d orbits; we discuss implications and possible explanations for this result. Finally, we compare chemical differences between the components of the wide binaries and the components of the candidate higher-order systems and find that any chemical influence or correlation due to the presence of close companions to wide binary stars is not discernible.

It seems we have some anticipations...

http://exoplanet.eu/catalog/2m_1252+2735_b/
http://exoplanet.eu/catalog/2m_1253+2734_b/
http://exoplanet.eu/catalog/2m_1258+2630_b/
http://exoplanet.eu/catalog/sand_178_b/

It seems there is a multiplanet system at Sand 178 (and not only) but unless some orbital periods are not reported correctly for the former one, it seems an unstable configuration:

http://exoplanet.eu/catalog/sand_178_c/
http://exoplanet.eu/catalog/sand_178_d/
http://exoplanet.eu/catalog/sand_178_e/

http://exoplanet.eu/catalog/2m_1252+2735_c/

I'm pretty sure what's going on there is that the exoplanet.eu site is reporting different orbit solutions (the paper shows there's a number of aliases in the RV fitting in some) as different planets.

Sirius_Alpha wrote:

I'm pretty sure what's going on there is that the exoplanet.eu site is reporting different orbit solutions (the paper shows there's a number of aliases in the RV fitting in some) as different planets.

Yes, very likely for Sand 178. For the latter system a multiplanet solution might be more plausible.

Two hot Jupiters discovered by Gaia and confirmed with RV.

The Detection of Transiting Exoplanets by Gaia
https://arxiv.org/abs/2205.10197

Gaia DR3 is out! And we've got extrasolar planets. 215 from transit, 74 from astrometry, 10 from RV.

Quote :

NAMING OF GAIA'S EXOPLANET CANDIDATES
The naming of the exoplanet candidates follows these three methods:

Astrometric detection: Gaia-ASOI-#
Photometric transit: Gaia-TROI-#
Radial velocity: Gaia-RVOI-#

Link to detected planets and candidates.
https://www.cosmos.esa.int/documents/29201/1658422/Gaia_Exoplanet_list_Version20220613.csv/6baa2406-c508-51c7-b471-02c1c6980734?t=1654699871498


Known planets detected by astrometry:
HD 175167 b, HD 164604 b, HD 132406 b, Iot Hor b, BD-17 0063 b, HD 111232 b, HD 81040 b, HD 142 b, GJ 876 b.

Known planets detected by radial velocity:
WASP-18b

And then the known planets from transit are just an enormous list.