相关论文: 'Oumuamua as a Cometary Fractal Aggregate: the "Du…

The first steps toward planet formation involve the coagulation of small microscopic grains into larger and larger pebbles and rocks in gas-rich disks around young stars and brown dwarfs. Observations in the sub-millimeter can trace…

Dust jets, i.e. fuzzy collimated streams of cometary material arising from the nucleus, have been observed in-situ on all comets since the Giotto mission flew by comet 1P/Halley in 1986. Yet their formation mechanism remains unknown.…

Measurements by dust detectors on interplanetary spacecraft appear to indicate a substantial flux of interstellar particles with masses exceeding 10^{-12}gram. The reported abundance of these massive grains cannot be typical of interstellar…

Filamentary enstatite crystals are found in interplanetary dust particles of likely cometary origin but are very rare or absent in meteorites. Crystallographic characteristics of filamentary enstatites indicate that they condensed directly…

The stellar halo contains some of the oldest stars in the Milky Way galaxy and in the universe. The detections of `Oumuamua, CNEOS 2014-01-08, and interstellar dust serve to calibrate the production rate of interstellar objects. We study…

There exists a number of astronomical spectral phenomena that have remained unidentified after decades of extensive observations. The diffuse interstellar bands, the 220 nm feature, unidentified infrared emission bands, extended red…

Context: Protoplanetary disks are observed to remain dust-rich for up to several million years. Theoretical modeling, on the other hand, raises several questions. Firstly, dust coagulation occurs so rapidly, that if the small dust grains…

Cometary dust provides a unique window on dust growth mechanisms during the onset of planet formation. Measurements by the Rosetta spacecraft show that the dust in the coma of comet 67P/Churyumov-Gerasimenko has a granular structure at size…

Models of the zodiacal cloud's thermal emission and sporadic meteoroids suggest Jupiter-family comets (JFCs) as the dominant source of interplanetary dust. However, comet sublimation is insufficient to sustain the quantity of dust presently…

The isothermal gravitational collapse and fragmentation of a region within a molecular cloud and the subsequent formation of a protostellar cluster is investigated numerically. The clump mass spectrum which forms during the fragmentation…

The interstellar medium is structured as a hierachy of gas clouds, that looks self-similar over 6 orders of magnitude in scales and 9 in masses. This is one of the more extended fractal in the Universe. At even larger scales, the ensemble…

We review the current state of observational work on the formation of brown dwarfs, focusing on their initial mass function, velocity and spatial distributions at birth, multiplicity, accretion, and circumstellar disks. The available…

The first interstellar object observed in our solar system, 1I/`Oumuamua, exhibited several peculiar properties, including extreme elongation and non-gravitational acceleration. Bergner and Seligman (hereafter BS23) proposed that…

Small angle scatterings of X-rays by interstellar dust particles create halos around x-ray sources. By observing these halos with sufficient angular resolution it is possible to derive information about both the spatial distribution of the…

We have calculated the radiation field, dust grain temperatures, and far infrared emissivity of numerical models of turbulent molecular clouds. When compared to a uniform cloud of the same mean optical depth, most of the volume inside the…

The chance discovery of the first interstellar minor body, 1I/2017 U1 (`Oumuamua), indicates that we may have been visited by such objects in the past and that these events may repeat in the future. Unfortunately, minor bodies following…

We present a quantitative model for the infrared emission from dust in the diffuse interstellar medium. The model consists of a mixture of amorphous silicate grains and carbonaceous grains, each with a wide size distribution ranging from…

Barnard 207 (B207, LDN 1489, LBN 777), also known as the Vulture Head nebula, is a cometary globule in the Taurus-Auriga-Perseus molecular cloud region. B207 is known to host a Class I protostar, IRAS 04016+2610, located at a projected…

We model the infrared emission from zodiacal dust detected by the IRAS and COBE missions, with the aim of estimating the relative contributions of asteroidal, cometary and interstellar dust to the zodiacal cloud. Our most important result…

Dust coagulation in a protoplanetary disk is the first step of planetesimal formation. However, a pathway from dust aggregates to planetesimals remains unclear. Both numerical simulations and laboratory experiments have suggested the…