Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userVariability and dust filtration in the transition disk J160421.7-213028 observed in optical scattered light
72
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Context. Some of transition disks show asymmetric structures in thermal sub-millimetre emission and optical scattered light. These structures can be the result of planet(s) or companions embedded in the disk. Aims. We aim to detect and analyse the scattered light of the transition disk J160421.7-213028, identify disk structures, and compare the results with previous observations of this disk at other wavelengths. Methods. We obtained and analysed new polarised intensity observations of the transition disk J160421.7-213028 with VLT/SPHERE using the visible light instrument ZIMPOL at $R$ band (0.626$mu$m). We probe the disk gap down to a radius of confidence of 0.1 (${sim}15$ AU at 145 pc). We interpret the results in the context of dust evolution when planets interact with the parental disk. Results. We observe a gap from 0.1 to 0.3 (${sim}15$ to 40AU) and a bright annulus as previously detected by HiCIAO $H$ band observations at $1.65mu$m. The radial width of the annulus is around $40$AU, and its centre is at ${sim}61$AU from the central star. The peak of the reflected light at 0.626$mu$m is located 20 AU inward of the cavity detected in the submillimetre. In addition, we detect a dip at a position angle of ${sim}46.2 pm 5.4^circ$. A dip was also detected with HiCIAO, but located at ${sim}85^circ$. If the dip observed with HiCIAO is the same, this suggests an average dip rotation of ${sim}12^circ/$year, which is inconsistent with the local Keplerian angular velocity of $sim$0.8$^circ$/yr at $sim$61AU. Conclusions. The spatial discrepancy in the radial emission in J160421.7-213028 at different wavelengths is consistent with dust filtration at the outer edge of a gap carved by a massive planet. The dip rotation can be interpreted by fast variability of the inner disk and/or the presence of a warp or circumplanetary material of a planet at ${sim}9.6$ AU.
rate research
Read More
We report ALMA Cycle 2 observations of 230 GHz (1.3 mm) dust continuum emission, and $^{12}$CO, $^{13}$CO, and C$^{18}$O J = 2-1 line emission, from the Upper Scorpius transitional disk [PZ99] J160421.7-213028, with an angular resolution of ~0.25 (35 AU). Armed with these data and existing H-band scattered light observations, we measure the size and depth of the disks central cavity, and the sharpness of its outer edge, in three components: sub-$mu$m-sized small dust traced by scattered light, millimeter-sized big dust traced by the millimeter continuum, and gas traced by line emission. Both dust populations feature a cavity of radius $sim$70 AU that is depleted by factors of at least 1000 relative to the dust density just outside. The millimeter continuum data are well explained by a cavity with a sharp edge. Scattered light observations can be fitted with a cavity in small dust that has either a sharp edge at 60 AU, or an edge that transitions smoothly over an annular width of 10 AU near 60 AU. In gas, the data are consistent with a cavity that is smaller, about 15 AU in radius, and whose surface density at 15 AU is $10^{3pm1}$ times smaller than the surface density at 70 AU; the gas density grades smoothly between these two radii. The CO isotopologue observations rule out a sharp drop in gas surface density at 30 AU or a double-drop model as found by previous modeling. Future observations are needed to assess the nature of these gas and dust cavities, e.g., whether they are opened by multiple as-yet-unseen planets or photoevaporation.
We present the first resolved near infrared imagery of the transition disk Oph IRS 48 (WLY 2-48), which was recently observed with ALMA to have a strongly asymmetric sub-millimeter flux distribution. H-band polarized intensity images show a $sim$60AU radius scattered light cavity with two pronounced arcs of emission, one from Northeast to Southeast and one smaller, fainter and more distant arc in the Northwest. K-band scattered light imagery reveals a similar morphology, but with a clear third arc along the Southwestern rim of the disk cavity. This arc meets the Northwestern arc at nearly a right angle, revealing the presence of a spiral arm or local surface brightness deficit in the disk, and explaining the East-West brightness asymmetry in the H-band data. We also present 0.8-5.4$mu$m IRTF SpeX spectra of this object, which allow us to constrain the spectral class to A0$pm$1 and measure a low mass accretion rate of 10$^{-8.5}$M$_{odot}$/yr, both consistent with previous estimates. We investigate a variety of reddening laws in order to fit the mutliwavelength SED of Oph IRS 48 and find a best fit consistent with a younger, higher luminosity star than previous estimates.
Debris disks or belts are important signposts for the presence of colliding planetesimals and, therefore, for ongoing planet formation and evolution processes in young planetary systems. Imaging of debris material at small separations from the star is very challenging but provides valuable insights into the spatial distribution of so-called hot dust produced by solid bodies located in or near the habitable zone. We report the first detection of scattered light from the hot dust around the nearby (d = 28.33 pc) A star HD 172555. We want to constrain the geometric structure of the detected debris disk using polarimetric differential Imaging (PDI) with a spatial resolution of 25 mas and an inner working angle of about 0.1$$. We measured the polarized light of HD 172555, with SPHERE-ZIMPOL, in the very broad band (VBB; $lambda=735$ nm) filter for the projected separations between 0.08$$ (2.3 au) and 0.77$$ (22 au). We constrained the disk parameters by fitting models for scattering of an optically thin dust disk taking the limited spatial resolution and coronagraphic attenuation of our data into account. The geometric structure of the disk in polarized light shows roughly the same orientation and outer extent as obtained from thermal emission at 18 $mu$m. Our image indicates the presence of a strongly inclined ($isim 103.5^circ$), roughly axisymmetric dust belt with an outer radius in the range between 0.3$$ (8.5 au) and 0.4$$ (11.3 au). We derive a lower limit for the polarized flux contrast ratio for the disk of $(F_{rm pol})_{rm disk}/F_{rm ast}> (6.2 pm 0.6)cdot 10^{-5}$ in the VBB filter. This ratio is small, only 9 %, when compared to the fractional infrared flux excess ($approx 7.2cdot 10^{-4}$). The model simulations show that more polarized light could be produced by the dust located inside 2 au, which cannot be detected with the instrument configuration used.
Debris disks around young main-sequence stars often have gaps and cavities which for a long time have been interpreted as possibly being caused by planets. In recent years, several giant planet discoveries have been made in systems hosting disks of precisely this nature, further implying that interactions with planets could be a common cause of such disk structures. As part of the SEEDS high-contrast imaging survey, we are surveying a population of debris disk-hosting stars with gaps and cavities implied by their spectral energy distributions, in order to attempt to spatially resolve the disk as well as to detect any planets that may be responsible for the disk structure. Here we report on intermediate results from this survey. Five debris disks have been spatially resolved, and a number of faint point sources have been discovered, most of which have been tested for common proper motion, which in each case has excluded physical companionship with the target stars. From the detection limits of the 50 targets that have been observed, we find that beta Pic b-like planets (~10 Mjup planets around G--A-type stars) near the gap edges are less frequent than 15--30%, implying that if giant planets are the dominant cause of these wide (27 AU on average) gaps, they are generally less massive than beta Pic b.
We have imaged GM Aur with HST, detected its disk in scattered light at 1400A and 1650A, and compared these with observations at 3300A, 5550A, 1.1 microns, and 1.6 microns. The scattered light increases at shorter wavelengths. The radial surface brightness profile at 3300A shows no evidence of the 24AU radius cavity that has been previously observed in sub-mm observations. Comparison with dust grain opacity models indicates the surface of the entire disk is populated with sub-micron grains. We have compiled an SED from 0.1 microns to 1 mm, and used it to constrain a model of the star+disk system that includes the sub-mm cavity using the Monte Carlo Radiative Transfer code by Barbara Whitney. The best-fit model image indicates that the cavity should be detectable in the F330W bandpass if the cavity has been cleared of both large and small dust grains, but we do not detect it. The lack of an observed cavity can be explained by the presence of sub-microns grains interior to the sub-mm cavity wall. We suggest one explanation for this which could be due to a planet of mass <9 Jupiter masses interior to 24 AU. A unique cylindrical structure is detected in the FUV data from the Advanced Camera for Surveys/Solar Blind Channel. It is aligned along the system semi-minor axis, but does not resemble an accretion-driven jet. The structure is limb-brightened and extends 190 +/- 35 AU above the disk midplane. The inner radius of the limb-brightening is 40 +/- 10 AU, just beyond the sub-millimeter cavity wall.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
