arXiv subjects

A. Potapov

Publications and source records attributed to A. Potapov.

2 recordsLinked to original sources

arXiv2026

Spatial distribution of water ice in the protoplanetary silhouette disk d216-0939

The composition of rocky planets depends on the dust in their natal protoplanetary disk (PPD), potentially containing water ice. Crystalline water ice was detected in the PPD d216-0939 in the Orion Nebular Cluster (ONC). We aim at constraining the spatial distribution and crystallization state of water ice in the d216-0939 disk using recent observations of the water ice absorption feature at a wavelength of $\sim 3\mathrm{\mu m}$ collected with JWST. We perform 3D Monte Carlo radiative transfer (MCRT) simulations to constrain the free parameters of an accretion disk model by fitting the calculated spectrum in the wavelength range from $1.6 \text{ to } 24\mathrm{\mu m}$ to the spectral energy distribution (SED) observed with the JWST instruments NIRSpec and MIRI. Additionally, archival, spatially resolved HST observations were used to constrain the global spatial structure of the disk, as the parameter space is degenerate with respect to the fit to the SED. Successively, we fit the water ice absorption feature using polychromatic MCRT simulations with spectral importance sampling to produce synthetic observations at high spectral resolutions. By probing the upper and outer disk layers, we found that a PPD model with dust containing 5.4% crystallized water ice beyond the snowline fits the observations well, necessitating outward transport of material, since crystalline ice is unlikely to form in situ in the probed disk layers. In the spectral region of the water ice absorption feature, scattering and thermal dust emission both contribute significantly to the total flux.

astro-ph.EP↗

arXiv2016

The CO-H2 van der Waals complex and complex organic molecules in cold molecular clouds: a TMC-1C survey

Almost 200 different species have been detected in the interstellar medium (ISM) during the last decades, revealing not only simple species but complex molecules with more than 6 atoms. Other exotic compounds, like the weakly-bound dimer (H2)2, have also been detected in astronomical sources like Jupiter. We aim at detecting for the first time the CO-H2 van der Waals complex in the ISM, which if detected can be a sensitive indicator for low temperatures. We use the IRAM30m telescope, located in Pico Veleta (Spain), to search for the CO-H2 complex in a cold, dense core in TMC-1C (with a temperature of 10 K). All the brightest CO-H2 transitions in the 3 mm (80-110 GHz) band have been observed with a spectral resolution of 0.5-0.7 km/s, reaching a rms noise level of 2 mK. The simultaneous observation of a broad frequency band, 16 GHz, has allowed us to conduct a serendipitous spectral line survey. No lines belonging to the CO-H2 complex have been detected. We have set up a new, more stringent upper limit for its abundance to be [CO-H2]/[CO] = 5x10^{-6}, while we expect the abundance of the complex to be in the range 10^{-8}-10^{-3}. The spectral line survey has allowed us to detect 75 lines associated with 41 different species (including isotopologues). We detect a number of complex organic species, e.g. methyl cyanide (CH3CN), methanol (CH3OH), propyne (CH3CCH) and ketene (CH2CO), associated with cold gas (excitation temperatures about 7 K), confirming the presence of these complex species not only in warm objects but also in cold regimes.

astro-ph.GA↗