The birth of a giant planet around HD 100546 ?

http://www.eso.org/public/news/eso1310/

« …Astronomers using ESO’s Very Large Telescope have obtained what is likely the first direct observation of a forming planet still embedded in a thick disc of gas and dust. If confirmed, this discovery will greatly improve our understanding of how planets form and allow astronomers to test the current theories against an observable target.
An international team led by Sascha Quanz (ETH Zurich, Switzerland) has studied the disc of gas and dust that surrounds the young star HD 100546, a relatively nearby neighbour located 335 light-years from Earth. They were surprised to find what seems to be a planet in the process of being formed, still embedded in the disc of material around the young star. The candidate planet would be a gas giant similar to Jupiter… »

There have been suggestions that the disc of HD 100546 is being sculpted by a giant planet before: it's been mentioned in the unconfirmed planets thread here (using the variable star designation KR Muscae) and here.

The possible protoplanet that's been imaged is not that planet - it is too far from the star.

More on the HD 100546 inner system:

Planet or Brown Dwarf? Inferring the Companion Mass in HD 100546 from the Wall Shape using Mid-Infrared Interferometry
http://arxiv.org/abs/1306.4264

From the abstract:

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The object in the disk gap of HD 100546 that shapes the disk wall is most likely a 60⁺²⁰_-40 M_Jup brown dwarf

However, from the conclusion, such an object cannot be the full explanation for the width of the gap:

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The effect of a single planet is not enough to explain the full width of the disk gap in HD 100546. Either an additional clearing mechanism, or a multi-planet system is required to explain its extent.

Boccaletti et al. "Multiple spiral patterns in the transitional disk of HD 100546"
http://arxiv.org/abs/1310.7092

Non-detection of the candidate protoplanet in the Ks band, they estimate an upper limit of 16–18 M_J.

Still not a confirmation...

Close to confirmation of HD 100546 b?

Recovery of the Candidate Protoplanet HD 100546 b with Gemini/NICI and Detection of Additional (Planet-Induced?) Disk Structure at Small Separations

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We report the first independent, second-epoch (re-)detection of a directly-imaged protoplanet candidate. Using L′ high-contrast imaging of HD 100546 taken with the Near-Infrared Coronagraph and Imager (NICI) on Gemini South, we recover `HD 100546 b' with a position and brightness consistent with the original VLT/NaCo detection from Quanz et al, although data obtained after 2013 will be required to decisively demonstrate common proper motion. HD 100546 b may be spatially resolved, up to ≈ 12-13 AU in diameter, and is embedded in a finger of thermal IR bright, polarized emission extending inwards to at least 0.3". Standard hot-start models imply a mass of ≈ 15 MJ. But if HD 100546 b is newly formed or made visible by a circumplanetary disk, both of which are plausible, its mass is significantly lower (e.g. 1--7 MJ). Additionally, we discover a thermal IR-bright disk feature, possibly a spiral density wave, at roughly the same angular separation as HD 100546 b but 90 degrees away. Our interpretation of this feature as a spiral arm is not decisive, but modeling analyses using spiral density wave theory implies a wave launching point exterior to ≈ 0.45" embedded within the visible disk structure: plausibly evidence for a second, hitherto unseen wide-separation planet. With one confirmed protoplanet candidate and evidence for 1--2 others, HD 100546 is an important evolutionary precursor to intermediate-mass stars with multiple super-jovian planets at moderate/wide separations like HR 8799.

Edasich wrote:

Close to confirmation of HD 100546 b?

Yep.

Confirmation and characterization of the protoplanet HD100546 b - Direct evidence for gas giant planet formation at 50 au
http://arxiv.org/abs/1412.5173

Quote :

We present the first multi-wavelength, high-contrast imaging study confirming the protoplanet embedded in the disk around the Herbig Ae/Be star HD100546. The object is detected at L' (~3.8 micron) and M' (~4.8 micron), but not at K_s (~2.1 micron), and the emission consists of a point source component surrounded by spatially resolved emission. For the point source component we derive apparent magnitudes of L'=13.92±0.10 mag, M'=13.33±0.16 mag, and K_s>15.43±0.11 mag (3-σ limit), and a separation and position angle of (0.457±0.014)'' and (8.4±1.4)∘, and (0.472±0.014)'' and (9.2±1.4)∘ in L' and M', respectively. We demonstrate that the object is co-moving with the central star and can reject any (sub-)stellar fore-/background object. Fitting a single temperature blackbody to the observed fluxes of the point source component yields an effective temperature of Teff=1028+227−253 K and a radius for the emitting area of R=6.0+2.5−2.6 Jupiter radii. The best-fit luminosity is L=(2.3+0.9−0.3)⋅10−4 solar luminosities. We quantitatively compare our findings with predictions from evolutionary and atmospheric models for young, gas giant planets, discuss the possible existence of a warm, circumplanetary disk, and note that the de-projected physical separation from the host star of (53±2) au poses a challenge standard planet formation theories. Considering the suspected existence of an additional planet orbiting at ~13-14 au, HD100546 is a unique laboratory to study the formation of multiple gas giant planets empirically.

If I understand it's two separate objets, one unconfirmed at 12-13 ua and one at 53 ua... but with the same name.

That's my understanding as well... if the suspect candidate at ~12-13 AU is confirmed, I would hope they would designated it HD 100546 c, respecting the order of confirmation.

http://spaceref.com/astronomy/observing-the-birth-of-a-planet.html

"...Yet the Very Large Telescope (VLT) in Chile spent an entire night with a high-resolution infrared camera pointed at a single object in the night sky. The data collected by the Naco optics instrument enabled an international team headed by ETH Zurich's Sascha Quanz to confirm its earlier hypothesis: that a young gas planet - presumed not unlike Jupiter in our own solar system - is orbiting the star designated HD 100546..."

Abstract of the Astrophysical Journal
http://iopscience.iop.org/0004-637X/807/1/64/pdf/0004-637X_807_1_64.pdf

Still the same problem with the names...

http://astronomynow.com/2015/09/14/astronomers-peer-into-the-amniotic-sac-of-a-planet-hosting-star/

High-resolution Br γ spectro-interferometry of the transitional Herbig Ae/Be star HD 100546: a Keplerian gaseous disc inside the inner rim

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We present spatially and spectrally resolved Br γ emission around the planet-hosting, transitional Herbig Ae/Be star HD 100546. Aiming to gain insight into the physical origin of the line in possible relation to accretion processes, we carried out Br γ spectro-interferometry using AMBER/VLTI from three different baselines achieving spatial and spectral resolutions of 2–4 mas and 12 000. The Br γ visibility is larger than that of the continuum for all baselines. Differential phases reveal a shift between the photocentre of the Br γ line – displaced ∼0.6 mas (0.06 au at 100 pc) NE from the star – and that of the K-band continuum emission – displaced ∼0.3 mas NE from the star. The photocentres of the redshifted and blueshifted components of the Br γ line are located NW and SE from the photocentre of the peak line emission, respectively. Moreover, the photocentre of the fastest velocity bins within the spectral line tends to be closer to that of the peak emission than the photocentre of the slowest velocity bins. Our results are consistent with a Br γ-emitting region inside the dust inner rim ( ≲ 0.25 au) and extending very close to the central star, with a Keplerian, disc-like structure rotating counter-clockwise, and most probably flared (∼25°). Even though the main contribution to the Br γ line does not come from gas magnetically channelled on to the star, accretion on to HD 100546 could be magnetospheric, implying a mass accretion rate of a few 10−7 M⊙ yr−1. This value indicates that the observed gas has to be replenished on time-scales of a few months to years, perhaps by planet-induced flows from the outer to the inner disc as has been reported for similar systems.

A little question, do you think accretion discs around protoplanets are conected magnetically to the protoplanet like the discs of youg stars?

A candidate second planet in HD 100546's disk

Resolving the HD 100546 Protoplanetary System with the Gemini Planet Imager: Evidence for Multiple Forming, Accreting Planets

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We report Gemini Planet Imager H band high-contrast imaging/integral field spectroscopy and polarimetry of the HD 100546, a 10 $Myr$-old early-type star recently confirmed to host a thermal infrared bright (super)jovian protoplanet at wide separation, HD 100546 b. We resolve the inner disk cavity in polarized light, recover the thermal-infrared (IR) bright arm, and identify one additional spiral arm. We easily recover HD 100546 b and show that much of its emission originates an unresolved, point source. HD 100546 b likely has extremely red infrared colors compared to field brown dwarfs, qualitatively similar to young cloudy superjovian planets, however, these colors may instead indicate that HD 100546 b is still accreting material from a circumplanetary disk. Additionally, we identify a second point source-like peak at $r_{proj}$ $\sim$ 13 AU, located just interior to or at inner disk wall consistent with being a 10--20 $M_{J}$ candidate second protoplanet-- "HD 100546 c" -- and lying within a weakly polarized region of the disk but along an extension of the thermal IR bright spiral arm. Alternatively, it is equally plausible that this feature is a weakly polarized but locally bright region of the inner disk wall. Astrometric monitoring of this feature over the next 2 years and emission line measurements could confirm its status as a protoplanet, rotating disk hot spot that is possibly a signpost of a protoplanet, or a stationary emission source from within the disk.

Possible structure crossing between the inner and outer discs, non-detection of HD 100546 c

Mendigutía et al. "The protoplanetary system HD 100546 in Hα polarized light from SPHERE/ZIMPOL. A bar-like structure across the disk gap?"
https://arxiv.org/abs/1711.00023

Clarifying the Status of HD 100546 as Observed by the Gemini Planet Imager
https://arxiv.org/abs/1712.02819

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HD 100546 is a young, early-type star and key laboratory for studying gas giant planet formation. GPI data taken in 2015 and reported by Currie et al. (2015) recover the previously-identified protoplanet candidate HD 100546 b and identify a second emission source at ~13--14 au: either a disk hot spot or a second protoplanetary candidate (HD 100546 "c").
In this short research note, we update the status of HD 100546 as observed by the Gemini Planet Imager by rereducing our original data using a different PSF subtraction method (KLIP instead of A-LOCI), rereducing recently public GPI Campaign Team (GPIES) data, and comparing the quality of the two data sets. Our results support the original findings in Currie et al. (2015).

High-Contrast study of the candidate planets and protoplanetary disk around HD~100546
https://arxiv.org/abs/1809.01001

Quote :

The nearby Herbig Be star HD100546 is known to be a laboratory for the study of protoplanets and their relation with the circumstellar disk that is carved by at least 2 gaps. We observed the HD100546 environment with high contrast imaging exploiting several different observing modes of SPHERE, including datasets with/without coronagraphs, dual band imaging, integral field spectroscopy and polarimetry. The picture emerging from these different data sets is complex. Flux-conservative algorithms images clearly show the disk up to 200au. More aggressive algorithms reveal several rings and warped arms overlapping the main disk. The bright parts of this ring lie at considerable height over the disk mid-plane at about 30au. Our images demonstrate that the brightest wings close to the star in the near side of the disk are a unique structure, corresponding to the outer edge of the intermediate disk at ~40au. Modeling of the scattered light from the disk with a geometrical algorithm reveals that a moderately thin structure can well reproduce the light distribution in the flux-conservative images. We suggest that the gap between 44 and 113 au span between the 1:2 and 3:2 resonance orbits of a massive body located at ~70au that might coincide with the candidate planet HD100546b detected with previous thermal IR observations. In this picture, the two wings can be the near side of a ring formed by disk material brought out of the disk at the 1:2 resonance with the same massive object. While we find no clear evidence confirming detection of the planet candidate HD100546c in our data, we find a diffuse emission close to the expected position of HD100546b. This source can be described as an extremely reddened substellar object surrounded by a dust cloud or its circumplanetary disk. Its astrometry is broadly consistent with a circular orbital motion on the disk plane.

Pérez et al. "Long baseline observations of HD100546 with ALMA: a possible circumplanetary disk detected in dust continuum and gas kinematics"
https://arxiv.org/abs/1906.06305

The source in question is at a deprojected separation (assuming coplanarity with the disc) of 7.8 AU.


Casassus & Pérez "Kinematic detections of protoplanets: a Doppler-flip in the disk of HD100546"
https://arxiv.org/abs/1906.06302

If the Doppler flip is due to planet-disc interaction, it suggests fast migration.

Some ALMA work modelling the influence of planets in the disk.

Constraining the properties of the potential embedded planets in the disk around HD 100546
https://arxiv.org/abs/2110.03373

Not a protoplanet?

The Origin of the Doppler-flip in HD 100546: a large scale spiral arm generated by an inner binary companion

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Companions at sub-arcsecond separation from young stars are difficult to image. However their presence can be inferred from the perturbations they create in the dust and gas of protoplanetary disks. Here we present a new interpretation of SPHERE polarised observations that reveal the previously detected inner spiral in the disk of HD 100546. The spiral coincides with a newly detected 12CO inner spiral and the previously reported CO emission Doppler-flip, which has been interpreted as the signature of an embedded protoplanet. Comparisons with hydrodynamical models indicate that this Doppler-flip is instead the kinematic counterpart of the spiral, which is likely generated by an inner companion inside the disk cavity.

Is this finally a confirmation?

Sulphur monoxide emission tracing an embedded planet in the HD 100546 protoplanetary disk

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Molecular line observations are powerful tracers of the physical and chemical conditions across the different evolutionary stages of star, disk and planet formation. Using the high angular resolution and unprecedented sensitivity of the Atacama Large Millimeter Array (ALMA) there is now a drive to detect small-scale gas structures in protoplanetary disks that can be attributed directly to forming planets. We report high angular resolution ALMA Band 7 observations of sulphur monoxide (SO) in the nearby planet-hosting disk around Herbig star HD 100546. SO is rarely detected in evolved protoplanetary disks but in other environments, it is most often utilised as a tracer of shocks. The SO emission from the HD 100546 disk is primarily originating from gas within the approx. 20 au mm-dust cavity and shows a clear azimuthal brightness asymmetry of a factor of 2. In addition, we see a significant difference in the line profile shape when comparing these new Cycle 7 data to Cycle 0 data of the same SO transitions. We discuss the different physical/chemical mechanisms that could be responsible for this asymmetry and time variability including disk winds, disk warps, and a shock triggered by a (forming) planet. We propose that the SO is enhanced in the cavity due to the presence of a giant planet. The SO asymmetry complements evidence for hot circumplanetary material around the giant planet HD 100546 c traced via CO ro-vibrational emission. This work sets the stage for further observational and modelling efforts to detect and understand the chemical imprint of a forming planet on its parent disk.

Not only HD 100546. Do you remember CS Cha?

The Giant Accreting Protoplanet Survey (GAPlanetS) -- Results from a Six Year Campaign to Image Accreting Protoplanets

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Accreting protoplanets represent a window into planet formation processes. We report H{\alpha} differential imaging results from the deepest and most comprehensive accreting protoplanet survey to date, acquired with the Magellan Adaptive Optics (MagAO) system's VisAO camera. The fourteen transitional disks targeted are ideal candidates for protoplanet discovery due to their wide, heavily depleted central cavities, wealth of non-axisymmetric circumstellar disk features evocative of ongoing planet formation, and ongoing stellar accretion. To address the twin challenges of morphological complexity in the target systems and PSF instability, we develop novel approaches for frame selection and optimization of the Karhounen-Loeve Image Processing algorithm pyKLIP. We detect one new candidate protoplanet, CS Cha "c", at a separation of 75mas and a {\Delta}mag of 5.1 and robustly recover the HD142527 B and HD100453 B low mass stellar companions across multiple epochs. Though we cannot rule out a substantial scattered light contribution to its emission, we also recover LkCa 15 b. Its presence inside of the cleared disk cavity and consistency with a forward-modeled point source suggest that it remains a viable protoplanet candidate. The protoplanet PDS 70 c was marginally recovered under our conservative general methodology. However, through targeted optimization in H{\alpha} imagery, we tentatively recover PDS 70 c in three epochs and PDS 70 b in one epoch. Of the many other previously-reported companions and companion candidates around objects in the sample, we do not recover any additional robust candidates. However, lack of recovery at moderate H{\alpha} contrast does not rule out the presence of protoplanets at these locations, and we report limiting H{\alpha} contrasts in such cases.