| PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk | |
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 1st July 2018, 8:31 pm | |
| Discovery of a planetary-mass companion within the gap of the transition disk around PDS 70 https://arxiv.org/abs/1806.11568 - Quote :
- Young circumstellar are of prime interest to understand the physical and chemical conditions under which planet formation takes place. Only very few detections of planet candidates within these disks exist, and most of them are currently suspected to be disk features. In this context, the transition disk around the young star PDS 70 is of particular interest, due to its large gap identified in previous observations, indicative of ongoing planet formation. We aim to search for the presence of planets and search for disk structures indicative for disk-planet interactions and other evolutionary processes. We analyse new and archival near-infrared (NIR) images of the transition disk PDS 70 obtained with the VLT/SPHERE, VLT/NaCo and Gemini/NICI instruments in polarimetric differential imaging (PDI) and angular differential imaging (ADI) modes. We detect a point source within the gap of the disk at about 195 mas (about 22 au) projected separation. The detection is confirmed at five different epochs, in three filter bands and using different instruments. The astrometry results in an object of bound nature, with high significance. The comparison of the measured magnitudes and colours to evolutionary tracks suggests that the detection is a companion of planetary mass. We confirm the detection of a large gap of about 54 au in size within the disk in our scattered light images, and detect a signal from an inner disk component. We find that its spatial extent is very likely smaller than about 17 au in radius. The images of the outer disk show evidence of a complex azimuthal brightness distribution which may in part be explained by Rayleigh scattering from very small grains. Future observations of this system at different wavelengths and continuing astrometry will allow us to test theoretical predictions regarding planet-disk interactions, planetary atmospheres and evolutionary models.
Orbital and atmospheric characterization of the planet within the gap of the PDS 70 transition disk https://arxiv.org/abs/1806.11567 - Quote :
- Aims: We aim to characterize the orbital and atmospheric properties of PDS 70 b, which was first identified on May 2015 in the course of the SHINE survey with SPHERE, the extreme adaptive-optics instrument at the VLT. Methods: We obtained new deep SPHERE/IRDIS imaging and SPHERE/IFS spectroscopic observations of PDS 70 b. The astrometric baseline now covers 6 years which allows us to perform an orbital analysis. For the first time, we present spectrophotometry of the young planet which covers almost the entire near-infrared range (0.96 to 3.8 micrometer). We use different atmospheric models covering a large parameter space in temperature, log(g), chemical composition, and cloud properties to characterize the properties of the atmosphere of PDS 70 b. Results: PDS 70 b is most likely orbiting the star on a circular and disk coplanar orbit at ~22 au inside the gap of the disk. We find a range of models that can describe the spectrophotometric data reasonably well in the temperature range between 1000-1600 K and log(g) no larger than 3.5 dex. The planet radius covers a relatively large range between 1.4 and 3.7 R_jupiter with the larger radii being higher than expected from planet evolution models for the age of the planet of 5.4 Myr. Conclusions: This study provides a comprehensive dataset on the orbital motion of PDS 70 b, indicating a circular orbit and a motion coplanar with the disk. The first detailed spectral energy distribution of PDS 70 b indicates a temperature typical for young giant planets. The detailed atmospheric analysis indicates that a circumplanetary disk may contribute to the total planet flux.
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 1st July 2018, 8:35 pm | |
| Image of PDS 70b. Rather spectacular image! _________________ Caps Lock: Cruise control for 'Cool'!
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 2nd July 2018, 6:37 am | |
| _________________ Caps Lock: Cruise control for 'Cool'!
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Led_Zep SuperJovian
Number of posts : 721 Location : France Registration date : 2011-09-09
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 3rd July 2018, 5:37 am | |
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Lazarus dF star
Number of posts : 3337 Registration date : 2008-06-12
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 3rd July 2018, 2:27 pm | |
| Good spot! That one is discussed in the Keppler et al. paper: - Quote :
- The first spatially resolved image of the disk was obtained by Riaud et al. (2006) together with the detection of a companion candidate at 2.2" to the North of the host star using the NaCo instrument in the Ks filter. The companion candidate was later identified as a background source (Hashimoto et al. 2012).
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Lazarus dF star
Number of posts : 3337 Registration date : 2008-06-12
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 31st July 2018, 2:11 am | |
| Wagner et al. "Magellan Adaptive Optics Imaging of PDS 70: Measuring the Mass Accretion Rate of a Young Giant Planet within a Gapped Disk" https://arxiv.org/abs/1807.10766Accretion rate estimated to be 10 -8±1 Jupiter masses per year, main contribution to the uncertainty is the amount of extinction from the circumstellar and circumplanetary discs. | |
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 16th May 2019, 9:17 pm | |
| Evidence for a circumplanetary disc around protoplanet PDS 70 b https://arxiv.org/abs/1905.06370 - Quote :
- We present the first observational evidence for a circumplanetary disc around the protoplanet PDS~70~b, based on a new spectrum in the K band acquired with VLT/SINFONI. We tested three hypotheses to explain the spectrum: Atmospheric emission from the planet with either (1) a single value of extinction or (2) variable extinction, and (3) a combined atmospheric and circumplanetary disc model. Goodness-of-fit indicators favour the third option, suggesting circumplanetary material contributing excess thermal emission --- most prominent at λ≳2.3μm. Inferred accretion rates (∼10−7.8--10−7.3MJ yr−1) are compatible with observational constraints based on the Hα and Brγ lines. For the planet, we derive an effective temperature of 1500--1600 K, surface gravity log(g)∼4.0, radius ∼1.6RJ, mass ∼10MJ, and possible thick clouds. Models with variable extinction lead to slightly worse fits. However, the amplitude (ΔAV≳3mag) and timescale of variation (≲~years) required for the extinction would also suggest circumplanetary material.
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 3rd June 2019, 5:19 pm | |
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 16th June 2019, 9:49 pm | |
| Submillimeter emission associated with candidate protoplanets https://arxiv.org/abs/1906.06308 - Quote :
- We present the discovery of a spatially unresolved source of sub-millimeter continuum emission (λ=855 μm) associated with a young planet, PDS 70 c, recently detected in Hα emission around the 5 Myr old T Tauri star PDS 70. We interpret the emission as originating from a dusty circumplanetary disk with a dust mass between 2×10−3 and 4.2×10−3 Earth masses. Assuming a standard gas-to-dust ratio of 100, the ratio between the total mass of the circumplanetary disk and the mass of the central planet would be between 10−4−10−5. Furthermore, we report the discovery of another compact continuum source located 0.074′′±0.013′′ South-West of a second known planet in this system, PDS 70 b, that was previously detected in near-infrared images. We speculate that the latter source might trace dust orbiting in proximity of the planet, but more sensitive observations are required to unveil its nature.
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Led_Zep SuperJovian
Number of posts : 721 Location : France Registration date : 2011-09-09
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 12th July 2019, 1:52 am | |
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 24th October 2019, 8:49 pm | |
| VLT/SPHERE exploration of the young multiplanetary system PDS70 https://arxiv.org/abs/1910.11169 - Quote :
- Context. PDS 70 is a young (5.4 Myr), nearby (~113 pc) star hosting a known transition disk with a large gap. Recent observations with SPHERE and NACO in the near-infrared (NIR) allowed us to detect a planetary mass companion, PDS70b, within the disk cavity. Moreover, observations in H_alpha with MagAO and MUSE revealed emission associated to PDS70b and to another new companion candidate, PDS70c, at a larger separation from the star. Aims. Our aim is to confirm the discovery of the second planet PDS70c using SPHERE at VLT, to further characterize its physical properties, and search for additional point sources in this young planetary system. Methods. We re-analyzed archival SPHERE NIR observations and obtained new data in Y, J, H and K spectral bands for a total of four different epochs. The data were reduced using the data reduction and handling pipeline and the SPHERE data center. We then applied custom routines (e.g. ANDROMEDA and PACO) to subtract the starlight. Results. We re-detect both PDS 70 b and c and confirm that PDS70c is gravitationally bound to the star. We estimate this second planet to be less massive than 5 M Jup and with a T_eff around 900 K. Also, it has a low gravity with log g between 3.0 and 3.5 dex. In addition, a third object has been identified at short separation (~0.12") from the star and gravitationally bound to the star. Its spectrum is however very blue, so that we are probably seeing stellar light reflected by dust and our analysis seems to demonstrate that it is a feature of the inner disk. We, however, cannot completely exclude the possibility that it is a planetary mass object enshrouded by a dust envelope. In this latter case, its mass should be of the order of few tens of M_Earth. Moreover, we propose a possible structure for the planetary system based on our data that, however, cannot be stable on a long timescale.
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Lazarus dF star
Number of posts : 3337 Registration date : 2008-06-12
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 19th March 2020, 1:10 pm | |
| Hashimoto et al. "Accretion Properties of PDS 70b with MUSE" https://arxiv.org/abs/2003.07922The planet is accreting at a rate >5×10 -7 Jupiter masses/year, versus ~6×10 -8 Jupiter masses/year for the star. PDS 70b and c are estimated as ~12 and ~11 Jupiter masses. | |
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 21st April 2020, 8:29 pm | |
| Keck/NIRC2 L'-Band Imaging of Jovian-Mass Accreting Protoplanets around PDS 70 https://arxiv.org/abs/2004.09597 - Quote :
- We present L'-band imaging of the PDS 70 planetary system with Keck/NIRC2 using the new infrared pyramid wavefront sensor. We detected both PDS 70 b and c in our images, as well as the front rim of the circumstellar disk. After subtracting off a model of the disk, we measured the astrometry and photometry of both planets. Placing priors based on the dynamics of the system, we estimated PDS 70 b to have a semi-major axis of 20+3−4~au and PDS 70 c to have a semi-major axis of 34+12−6~au (95\% credible interval). We fit the spectral energy distribution (SED) of both planets. For PDS 70 b, we were able to place better constraints on the red half of its SED than previous studies and inferred the radius of the photosphere to be 2-3~RJup. The SED of PDS 70 c is less well constrained, with a range of total luminosities spanning an order of magnitude. With our inferred radii and luminosities, we used evolutionary models of accreting protoplanets to derive a mass of PDS 70 b between 2 and 4 MJup and a mean mass accretion rate between 3×10−7 and 8×10−7 MJup/yr. For PDS 70 c, we computed a mass between 1 and 3 MJup and mean mass accretion rate between 1×10−7 and 5× 10−7MJup/yr. The mass accretion rates imply dust accretion timescales short enough to hide strong molecular absorption features in both planets' SEDs.
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 12th January 2021, 9:57 pm | |
| Constraining the Nature of the PDS 70 Protoplanets with VLTI/GRAVITY https://arxiv.org/abs/2101.04187 - Quote :
- We present K-band interferometric observations of the PDS 70 protoplanets along with their host star using VLTI/GRAVITY. We obtained K-band spectra and 100 μas precision astrometry of both PDS 70 b and c in two epochs, as well as spatially resolving the hot inner disk around the star. Rejecting unstable orbits, we found a nonzero eccentricity for PDS 70 b of 0.17±0.06, a near-circular orbit for PDS 70 c, and an orbital configuration that is consistent with the planets migrating into a 2:1 mean motion resonance. Enforcing dynamical stability, we obtained a 95% upper limit on the mass of PDS 70 b of 10 MJup, while the mass of PDS 70 c was unconstrained. The GRAVITY K-band spectra rules out pure blackbody models for the photospheres of both planets. Instead, the models with the most support from the data are planetary atmospheres that are dusty, but the nature of the dust is unclear. Any circumplanetary dust around these planets is not well constrained by the planets' 1-5 μm spectral energy distributions (SEDs) and requires longer wavelength data to probe with SED analysis. However with VLTI/GRAVITY, we made the first observations of a circumplanetary environment with sub-au spatial resolution, placing an upper limit of 0.3~au on the size of a bright disk around PDS 70 b.
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Sirius_Alpha Admin
Number of posts : 4319 Location : Earth Registration date : 2008-04-06
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 29th April 2021, 3:59 pm | |
| Hubble Watches How a Giant Planet Grows https://www.nasa.gov/feature/goddard/2021/hubble-watches-how-a-giant-planet-grows - Quote :
The researchers hypothesize that magnetic field lines extend from its circumplanetary disk down to the exoplanet’s atmosphere and are funneling material onto the planet’s surface.
“If this material follows columns from the disk onto the planet, it would cause local hot spots,” Zhou explained. “These hot spots could be at least 10 times hotter than the temperature of the planet.” These hot patches were found to glow fiercely in UV light. Edit: now on arXiv. Hubble Space Telescope UV and Hα Measurements of the Accretion Excess Emission from the Young Giant Planet PDS 70 b https://arxiv.org/abs/2104.13934 _________________ Caps Lock: Cruise control for 'Cool'!
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Led_Zep SuperJovian
Number of posts : 721 Location : France Registration date : 2011-09-09
| Subject: Re: PDS 70 - Imaged protoplanet clearing gap in protoplanetary disk 22nd July 2021, 9:56 am | |
| https://www.eso.org/public/unitedkingdom/news/eso2111/Astronomers make first clear detection of a moon-forming disc around an exoplanet Using the Atacama Large Millimetre/submillimeter Array (ALMA), in which the European Southern Observatory (ESO) is a partner, astronomers have unambiguously detected the presence of a disc around a planet outside our Solar System for the first time. The observations will shed new light on how moons and planets form in young stellar systems. | |
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