HD 95086 b - ~4.5 M_J planet from direct imaging

A gas giant planet orbiting HD 95086 from direct imaging. It's the lightest planet directly imaged (Fomalhaut b... whatever that actually is... notwithstanding)

Discovery of a probable 4-5 Jupiter-mass exoplanet to HD 95086 by direct-imaging
http://arxiv.org/abs/1305.7428

Further Evidence of the Planetary Nature of HD 95086 b from Gemini/NICI H-band Data
http://arxiv.org/abs/1309.0543

H-band non-detection supporting a sub-stellar upper mass limit.

A resolved debris disk around the candidate planet-hosting star HD95086
http://arxiv.org/abs/1309.1675

Looks like the system has an inclination of 25 degrees, with the planet on the edge of the disk.

Confirmation of the planet around HD 95086 by direct imaging
http://arxiv.org/abs/1310.7483

Quote :

VLT/NaCo angular differential imaging at L' (3.8 microns) revealed a probable giant planet comoving with the young and early-type HD 95086 also known to harbor an extended debris disk. The discovery was based on the proper motion analysis of two datasets spanning 15 months. However, the second dataset suffered from bad atmospheric conditions, which limited the significance of the redetection at the 3 sigma level. In this Letter, we report new VLT/NaCo observations of HD 95086 obtained on 2013 June 26-27 at L' to recover the planet candidate. We unambiguously redetect the companion HD 95086 b with multiple independent pipelines at a signal-to-noise ratio greater than or equal to 5. Combined with previously reported measurements, our astrometry decisively shows that the planet is comoving with HD 95086 and inconsistent with a background object. With a revised mass of 5 pm 2 Jupiter masses, estimated from its L' photometry and "hot-start" models at 17 pm 4 Myr, HD 95086 b becomes a new benchmark for further physical and orbital characterization of young giant planets.

GPI detection of HD 95086 b
http://arxiv.org/abs/1404.4635

http://spaceref.com/astronomy/follow-the-dust-to-find-planets.html

"...Researchers studying what appears to be a beefed-up version of our solar system have discovered that it is encased in a halo of fine dust. The findings are based on infrared data from NASA's Spitzer Space Telescope and the European Space Agency's Herschel Space Observatory, in which NASA is a partner..."

I was not sure whether opening a separate thread about this paper:

Planets Around Low-Mass Stars (PALMS). IV. The Outer Architecture of M Dwarf Planetary Systems

Quote :

We present results from a high-contrast adaptive optics imaging search for giant planets and brown dwarfs (>1 MJup) around 122 newly identified nearby (<40 pc) young M dwarfs. Half of our targets are younger than 135 Myr and 90% are younger than the Hyades (620 Myr). Our H- and K-band coronagraphic observations with Keck/NIRC2 and Subaru/HiCIAO achieve typical contrasts of 12-14 mag and 9-13 mag at 1", respectively, which corresponds to limiting planet masses of 0.5-10 MJup at 5-33 AU for 85% of our sample. We discovered four young brown dwarf companions: 1RXS J235133.3+312720 B (32 ± 6 MJup; L0+2−1; 120 ± 20 AU), GJ 3629 B (64+30−23 MJup; M7.5 ± 0.5; 6.5 ± 0.5 AU), 1RXS J034231.8+121622 B (35 ± 8 MJup; L0 ± 1; 19.8 ± 0.9 AU), and 2MASS J15594729+4403595 B (43 ± 9 MJup; M8.0 ± 0.5; 190 ± 20 AU). Over 150 candidate planets were identified; we obtained follow-up imaging for 56% of these but all are consistent with background stars. Our null detection of planets enables strong statistical constraints on the occurrence rate of long-period giant planets around single M dwarfs. We infer an upper limit (at the 95% confidence level) of 10.3% and 16.0% for 1-13 MJup planets between 10-100 AU for hot-start and cold-start (Fortney) evolutionary models, respectively. Fewer than 6.0% (9.9%) of M dwarfs harbor massive gas giants in the 5-13 MJup range like those orbiting HR 8799 and β Pictoris between 10-100 AU for a hot-start (cold-start) formation scenario. Although the first directly imaged planets were found around massive stars, there is currently no statistical evidence for a trend of giant planet frequency with stellar host mass at large separations as predicted by the disk instability model of giant planet formation.

Hmmm that one's about planets around M dwarfs, while HD 95086 is an A8 star. So I'd go with a separate thread...

Interesting result on the statistical dependence though: perhaps the dearth of RV giant planets around low-mass stars is due to M dwarfs being less efficient at migrating the planets into the inner system rather than being less good at forming such objects, or that the wide-orbit objects are formed by a different mechanism (disc instabllity) than gas giant planets closer in.

It's now on arXiv.

Debris Distribution in HD 95086 - A Young Analog of HR 8799
http://arxiv.org/abs/1412.0167

Outer disk at ~55 K, warm disk at ~175 K, unconfirmed third component at ~300 K suggesting forming terrestrial planets. Cold halo out to ~800 AU. Spectrum consistent with iron-poor, crystalline olivine likely comprising ~5% of the disk.

The gap between the warm and cold disk can be explained by the presence of planets. For the b planet alone to produce the gap, it needs an eccentricity of 0.7 to clear out the gap. They find that the presence of three planets of ~7 M_J at 12, 26, 56 AU can maintain the gap and be stable. Four planets can accomplish this as well, but with some significant fine-tuning with mean motion resonances (which may be the case at HR 8799 anyway).

Spectroscopic characterization of HD 95086 b with the Gemini Planet Imager
http://arxiv.org/abs/1604.01411

Chauvin et al. "Investigating the young Solar System analog HD95086"
https://arxiv.org/abs/1801.05850

Astrometry favours a low-eccentricity orbit coplanar with the debris disc. The planet's spectral type is estimated between L7–L9, and a mass of 4–5 Jupiter masses.

A circumplanetary ring around HD 95086 b is detected

In-depth direct imaging and spectroscopic characterization of the young Solar System analog HD 95086

Quote :

Context. HD 95086 is a young nearby Solar System analog hosting a giant exoplanet orbiting at 57 au from the star between an inner and outer debris belt. The existence of additional planets has been suggested as the mechanism that maintains the broad cavity between the two belts.
Aims. We present a dedicated monitoring of HD 95086 with the VLT/SPHERE instrument to refine the orbital and atmospheric properties of HD 95086 b, and to search for additional planets in this system.
Methods. SPHERE observations, spread over ten epochs from 2015 to 2019 and including five new datasets, were used. Combined with archival observations, from VLT/NaCo (2012-2013) and Gemini/GPI (2013-2016), the extended set of astrometric measurements allowed us to refine the orbital properties of HD 95086 b. We also investigated the spectral properties and the presence of a circumplanetary disk around HD 95086 b by using the special fitting tool exploring the diversity of several atmospheric models. In addition, we improved our detection limits in order to search for a putative planet c via the K-Stacker algorithm.
Results. We extracted for the first time the JH low-resolution spectrum of HD 95086 b by stacking the six best epochs, and confirm its very red spectral energy distribution. Combined with additional datasets from GPI and NaCo, our analysis indicates that this very red color can be explained by the presence of a circumplanetary disk around planet b, with a range of high-temperature solutions (1400-1600 K) and significant extinction (Av > 10 mag), or by a super-solar metallicity atmosphere with lower temperatures (800-1300 K), and small to medium amount of extinction (Av < 10 mag). We do not find any robust candidates for planet c, but give updated constraints on its potential mass and location.