Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThe Transitional Disk around IRAS 04125+2902
469
0
0.0
(
0
)
Added by
Catherine Espaillat
Publication date
2015
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
Resolved submillimeter imaging of transitional disks is increasingly revealing the complexity of disk structure. Here we present the first high-resolution submillimeter image of a recently identified transitional disk around IRAS 04125+2902 in the Taurus star-forming region. We measure an inner disk hole of ~20 AU around IRAS 04125+2902 by simultaneously modeling new 880 micron Submillimeter Array (SMA) data along with an existing spectral energy distribution supplemented by new Discovery Channel Telescope (DCT) photometry. We also constrain the outer radius of the dust disk in IRAS~04125+2902 to ~50-60 AU. Such a small dust disk could be attributed to initial formation conditions, outward truncation by an unseen companion, or dust evolution in the disk. Notably, the dust distribution of IRAS 04125+2902 resembles a narrow ring (delta R ~ 35 AU) composed of large dust grains at the location of the disk wall. Such narrow dust rings are also seen in other transitional disks and may be evidence of dust trapping in pressure bumps, possibly produced by planetary companions. More sensitive submillimeter observations of the gas are necessary to further probe the physical mechanisms at work in shaping the spatial distribution of large dust in this disk. Interestingly, the IRAS 04125+2902 disk is significantly fainter than other transitional disks that have been resolved at submillimeter wavelengths, hinting that more objects with large disk holes may exist at the faint end of the submillimeter luminosity distribution that await detection with more sensitive imaging telescopes.
rate research
Read More
Simple molecules like H2CO and CH3OH in protoplanetary disks are the starting point for the production of more complex organic molecules. So far, the observed chemical complexity in disks has been limited due to freeze out of molecules onto grains in the bulk of the cold outer disk. Complex molecules can be studied more directly in transitional disks with large inner holes, as these have a higher potential of detection, through UV heating of the outer disk and the directly exposed midplane at the wall. We use Atacama Large Millimeter/submillimeter Array (ALMA) Band 9 (~680 GHz) line data of the transitional disk Oph IRS 48, previously shown to have a large dust trap, to search for complex molecules in regions where planetesimals are forming. We report the detection of the H2CO 9(1,8)-8(1,7) line at 674 GHz, which is spatially resolved as a semi-ring at ~60 AU radius centered south from the star. The inferred H2CO abundance is ~10^{-8} derived by combining a physical disk model of the source with a non-LTE excitation calculation. Upper limits for CH3OH lines in the same disk give an abundance ratio H2CO/CH3OH>0.3, which points to both ice formation and gas-phase routes playing a role in the H2CO production. Upper limits on the abundances of H13CO+, CN and several other molecules in the disk are also derived and found to be consistent with full chemical models. The detection of the H2CO line demonstrates the start of complex organic molecules in a planet-forming disk. Future ALMA observations should be able to push down the abundance detection limits of other molecules by 1-2 orders of magnitude and test chemical models of organic molecules in (transitional) disks.
Protoplanetary disks around young stars harbor many structures related to planetary formation. Of particular interest, spiral patterns were discovered among several of these disks and are expected to be the sign of gravitational instabilities leading to giant planets formation or gravitational perturbations caused by already existing planets. In this context, the star HD100546 presents some specific characteristics with a complex gas and dusty disk including spirals as well as a possible planet in formation. The objective of this study is to analyze high contrast and high angular resolution images of this emblematic system to shed light on critical steps of the planet formation. We retrieved archival images obtained at Gemini in the near IR (Ks band) with the instrument NICI and processed the data using advanced high contrast imaging technique taking advantage of the angular differential imaging. These new images reveal the spiral pattern previously identified with HST with an unprecedented resolution, while the large-scale structure of the disk is mostly erased by the data processing. The single pattern at the southeast in HST images is now resolved into a multi-armed spiral pattern. Using two models of a gravitational perturber orbiting in a gaseous disk we attempted to bring constraints on the characteristics of this perturber assuming each spiral being independent and we derived qualitative conclusions. The non-detection of the northeast spiral pattern observed in HST allows to put a lower limit on the intensity ratio between the two sides of the disk, which if interpreted as forward scattering yields a larger anisotropic scattering than derived in the visible. Also, we found that the spirals are likely spatially resolved with a thickness of about 5-10AU. Finally, we did not detect the candidate forming planet recently discovered in the Lp band, with a mass upper limit of 16-18 MJ.
We report the detection of a faint pointlike feature possibly related to ongoing planet-formation in the disk of the transition disk star HD 169142. The pointlike feature has a $Delta$mag(L)$sim$6.4, at a separation of $sim$0.11 and PA$sim$0$^{circ}$. Given its lack of an H or K$_{S}$ counterpart despite its relative brightness, this candidate cannot be explained by purely photospheric emission and must be a disk feature heated by an as yet unknown source. Its extremely red colors make it highly unlikely to be a background object, but future multi-wavelength followup is necessary for confirmation and characterization of this feature.
We have obtained a full suite of Spitzer observations to characterize the debris disk around HR 8799 and to explore how its properties are related to the recently discovered set of three massive planets orbiting the star. We distinguish three components to the debris system: (1) warm dust (T ~150 K) orbiting within the innermost planet; (2) a broad zone of cold dust (T ~45 K) with a sharp inner edge, orbiting just outside the outermost planet and presumably sculpted by it; and (3) a dramatic halo of small grains originating in the cold dust component. The high level of dynamical activity implied by this halo may arise due to enhanced gravitational stirring by the massive planets. The relatively young age of HR 8799 places it in an important early stage of development and may provide some help in understanding the interaction of planets and planetary debris, an important process in the evolution of our own solar system.
PDS70 is a unique system in which two protoplanets, PDS70b and c, have been discovered within the dust-depleted cavity of their disk, at $sim$22 and 34au respectively, by direct imaging at infrared wavelengths. Subsequent detection of the planets in the H$alpha$ line indicates that they are still accreting material through circumplanetary disks. In this Letter, we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of the dust continuum emission at 855$mu$m at high angular resolution ($sim$20mas, 2.3au) that aim to resolve the circumplanetary disks and constrain their dust masses. Our observations confirm the presence of a compact source of emission co-located with PDS70c, spatially separated from the circumstellar disk and less extended than $sim$1.2au in radius, a value close to the expected truncation radius of the cicumplanetary disk at a third of the Hill radius. The emission around PDS70c has a peak intensity of $sim$86$pm$16 $mu mathrm{Jy}~mathrm{beam}^{-1}$ which corresponds to a dust mass of $sim$0.031M$_{oplus}$ or $sim$0.007M$_{oplus}$, assuming that it is only constituted of 1 $mu$m or 1 mm sized grains, respectively. We also detect extended, low surface brightness continuum emission within the cavity near PDS70b. We observe an optically thin inner disk within 18au of the star with an emission that could result from small micron-sized grains transported from the outer disk through the orbits of b and c. In addition, we find that the outer disk resolves into a narrow and bright ring with a faint inner shoulder.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
