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In order to investigate possible connections between dust processing and disk properties, 8--13 um spectra of 34 young stars, with a range of circumstellar environments and spectral types A to M, were obtained using the Long Wavelength…

Astrophysics · Physics 2009-11-10 J. E. Kessler-Silacci , L. A. Hillenbrand , G. A. Blake , M. R. Meyer

Cosmic dust models are key ingredients in advancing our understanding of astronomical environments as diverse as interstellar clouds in galaxies, circumstellar envelopes around evolved and young stars, and protoplanetary disks. Such models…

Astrophysics of Galaxies · Physics 2022-11-02 K. Demyk , V. Gromov , C. Meny , N. Ysard , D. Paradis , A. P. Jones , D. Petitprez , P. Hubert , H. Leroux , C. Nayral , F. Delpech

Observations performed with high-resolution imaging techniques revealed the existence of shadows in circumstellar disks that can be explained by the misalignment of an inner with respect to an outer disk. The cause of misalignment, however,…

Solar and Stellar Astrophysics · Physics 2024-06-05 A. Krieger , M. Kuffmeier , S. Reissl , C. P. Dullemond , C. Ginski , S. Wolf

In the framework of the silicate core-carbonaceous organic mantle interstellar dust model, the bulk of the visual/near-IR extinction and the entire polarization are from nonspherical and aligned core-mantle grains. The 3.4 micron C-H and…

Astrophysics · Physics 2009-11-07 Aigen Li , J. Mayo Greenberg

The silicate cross section peak near 10um produces emission and absorption features in the spectra of dusty galactic nuclei observed with the Spitzer Space Telescope. Especially in ultraluminous infrared galaxies, the observed absorption…

Astrophysics · Physics 2010-11-11 N. A. Levenson , M. M. Sirocky , L. Hao , H. W. W. Spoon , J. A. Marshall , M. Elitzur , J. R. Houck

Low mass (sub)stellar objects represent the low end of the initial mass function, the transition to free-floating planets and a prominent interloper population in the search for high-redshift galaxies. Without proper motions or…

Wolf-Lundmark-Melotte (WLM) is a Local Group dwarf irregular (dIrr) galaxy with a metallicity 13% of solar. At 1 Mpc, the relative isolation of WLM provides a unique opportunity to investigate the internal mechanisms of star formation at…

Polarized emission from aligned dust is a crucial tool for studies of magnetism in the ISM and a troublesome contaminant for studies of CMB polarization. In each case, an understanding of the significance of the polarization signal requires…

Many of the confirmed short period super-Earths and smaller sub-Neptunes are sufficiently irradiated for the surface silicates to be sustained in a long-lasting molten state. While there is no direct evidence of magma ocean influence on…

Earth and Planetary Astrophysics · Physics 2023-03-22 Mantas Zilinskas , Yamila Miguel , Chritstiaan P. A. van Buchem , Ignas A. G. Snellen

Infrared Space Observatory (ISO) observations have shown that O-rich Asymptotic Giant Branch (AGB) stars exhibit crystalline silicate features in their spectra only if their mass-loss rate is higher than a certain threshold value. Usually,…

Astrophysics · Physics 2009-01-06 F. Kemper , L. B. F. M. Waters , A. de Koter , A. G. G. M. Tielens

GQ Lup B is a forming brown dwarf companion ($M\sim10-30~M_J$) showing evidence for an infrared excess associated with a disk surronding the companion itself. Here we present mid-infrared (MIR) observations of GQ Lup B with the Medium…

Spitzer Space Telescope spectra reveal 10 micron silicate emission from circumstellar dust orbiting six externally-polluted white dwarfs. Micron-size glasses with an olivine stoichiometry can account for the distinctively broad wings that…

Astrophysics · Physics 2009-11-13 M. Jura , J. Farihi , B. Zuckerman

As comets journey into the inner solar system, they deliver particulates and volatile gases into their comae that reveal the most primitive materials in the solar system. Cometary dust particles provide crucial information for assessing the…

Earth and Planetary Astrophysics · Physics 2023-09-28 David E. Harker , Diane H. Wooden , Michael S. P. Kelley , Charles E. Woodward

This study present a comparison of lidar observations of midlatitude cirrus clouds over the SIRTA observatory between 2002 and 2006 with multiple tropopauses (MT) retrieved from radiosounding temperature profiles. The temporal variability…

Atmospheric and Oceanic Physics · Physics 2008-03-05 Vincent Noel , Martial Haeffelin

This paper addresses the origin of the silicate emission observed in PG QSOs, based on observations with the Spitzer Space Telescope. Scenarios based on the unified model suggest that silicate emission in AGN arises mainly from the…

We report long-baseline interferometric measurements of circumstellar dust around massive evolved stars with the MIDI instrument on the Very Large Telescope Interferometer and provide spectrally dispersed visibilities in the 8-13 micron…

Theoretical arguments and observations suggest that the atmospheres of Brown Dwarfs and planets are very dynamic on chemical and on physical time scales. The modelling of such substellar atmospheres has, hence, been much more demanding than…

Solar and Stellar Astrophysics · Physics 2010-12-15 Ch. Helling , E. Pedretti , S. Berdyugina , A. A. Vidotto , B. Beeck , E. Baron , A. P. Showman , E. Agol , D. Homeier

We present the first spectral features obtained from Cassini's Composite Infrared Spectrometer (CIRS) for any icy moon. The spectral region covered by CIRS focal planes (FP) 3 and 4 is rich in emissivity features, but previous studies at…

Progress in understanding star formation requires detailed observational constraints on the initial conditions, i.e. dense clumps and cores in giant molecular clouds that are on the verge of gravitational instability. Such structures have…

Solar and Stellar Astrophysics · Physics 2016-09-23 Wanggi Lim , Jonathan C. Tan

Clouds of metal-bearing condensates play a critical role in shaping the emergent spectral energy distributions of the coolest classes of low-mass stars and brown dwarfs, L and T dwarfs. Because condensate clouds in planetary atmospheres…