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We present newly processed archival Herschel images of molecular cloud MCLD 123.5+24.9 in the Polaris Flare. This cloud contains five starless cores. Using the spectral synthesis code Cloudy, we explore uncertainties in the derivation of…

星系天体物理 · 物理学 2015-08-10 Gururaj A. Wagle , Thomas H. Troland , Gary J. Ferland , Nicholas P. Abel

Carbon monoxide (CO) is a poor tracer of H$_{2}$ in the diffuse interstellar medium (ISM), where most of the carbon is not incorporated into CO molecules unlike the situation at higher extinctions. We present a novel, indirect method to…

星系天体物理 · 物理学 2023-12-18 Raphael Skalidis , Paul F. Goldsmith , Philip F. Hopkins , Sam B. Ponnada

(abridged) We correlated near-infrared stellar H-Ks colour excesses of background stars from NTT/SOFI with the far-IR optical depth map, tauFIR, derived from Herschel 160, 250, 350, and 500 um data. The Herschel maps were also used to…

Using 12CO and 13CO observations we present column density maps of the molecular cloud (V = -135 km/s) in the direction of 1E1740.7-2942. Hydrogen column densities of the cloud scatter between (3.5 - 11) 10**22 cm-2, depending on the method…

天体物理学 · 物理学 2007-05-23 O. Vilhu , D. Hannikainen , P. Muhli , J. Huovelin , J. Poutanen , Ph. Durouchoux , P. Wallyn

Light scattering at near-infrared wavelengths has been used to study the optical properties of the interstellar dust grains, but these studies are limited by the assumptions on the strength of the radiation field. On the other hand, thermal…

星系天体物理 · 物理学 2021-03-24 M. Saajasto , M. Juvela , C. Lefevre , L. Pagani , N. Ysard

Context: Observations of scattered light in the 1-5 $\mu$m range have revealed dust grains in molecular cores with sizes larger than commonly inferred for the diffuse interstellar medium. It is currently unclear whether these grains are…

星系天体物理 · 物理学 2014-09-05 M. Andersen , W-F. Thi , J. Steinacker , N. Tothill

We have performed a 5-colour surface photometric study of the high-galactic-latitude area of dark nebula LDN 1642. Scattered light properties are presented of diffuse, translucent and opaque dust over the range of 3500 -- 5500 A. Far…

星系天体物理 · 物理学 2023-07-05 K. Mattila , P. Väisänen , K. Lehtinen , L. Haikala , M. Haas

We examine the cloud structure around the Planck detections in 71 fields observed with the Herschel SPIRE instrument. We wish to determine the general physical characteristics of the fields and to examine the morphology of the clouds where…

The effects of external irradiation on the chemistry and physics in the protostellar envelope around low-mass young stellar objects are poorly understood. The Corona Australis star-forming region contains the R CrA dark cloud, comprising…

We study the correlation between far-infared/submm dust emission and atomic gas column density in order to derive the properties of the high Galactic latitude, low density, Milky Way cirrus in the foreground of the Virgo cluster of…

Dust emission is an important tool in studies of star-forming clouds, as a tracer of column density and indirectly via the dust evolution that is connected to the history and physical conditions of the clouds. We examine radiative transfer…

星系天体物理 · 物理学 2024-01-24 M. Juvela

We present a model for the diffuse interstellar dust that explains the observed wavelength-dependence of extinction, emission, linear and circular polarisation of light. The model is set-up with a small number of parameters. It consists of…

星系天体物理 · 物理学 2015-06-16 R. Siebenmorgen , N. V. Voshchinnikov , S. Bagnulo

Theoretical arguments suggest that dust grains should grow in the dense cold parts of molecular clouds. Evidence of larger grains has so far been gathered in near/mid infrared extinction and millimeter observations. Interpreting the data…

星系天体物理 · 物理学 2015-05-14 J. Steinacker , L. Pagani , A. Bacmann , S. Guieu

Whether supernovae are major sources of dust in galaxies is a long-standing debate. We present infrared and submillimeter photometry and spectroscopy from the Herschel Space Observatory of the Crab Nebula between 51 and 670 micron as part…

We analyze the X-ray scattering halos around three Galactic Anomalous X-ray Pulsars (AXPs) in order to constrain the distance and the optical extinction of each source. We obtain surface brightness distributions from EPIC-pn data obtained…

星系天体物理 · 物理学 2010-01-26 A. Rivera-Ingraham , M. H. van Kerkwijk

Cores and filamentary structures are the prime birthplaces of stars, and play key roles in the process of star formation. Latest advances in the methods of multi-scale source and filament extraction, and in making high-resolution column…

星系天体物理 · 物理学 2022-05-04 Chang Zhang , Guo-Yin Zhang , Jin-Zeng Li , Xue-Mei Li

We study an undocumented large translucent cloud, detected by means of its enhanced radiation on the SHASSA (Southern H-Alpha Sky Survey Atlas) survey. We consider whether its excess surface brightness can be explained by light scattered…

星系天体物理 · 物理学 2015-05-19 K. Lehtinen , M. Juvela , K. Mattila

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…

天体物理学 · 物理学 2009-11-10 Thomas Bethell , Ellen Zweibel , Fabian Heitsch , J. S. Mathis

Context: In the last years, there have been many studies on the omnipresence and structures of filaments in star-forming regions, as well as their role in the process of star formation. Those filaments are normally identified as elongated…

星系天体物理 · 物理学 2016-08-10 R. -A. Chira , R. Siebenmorgen , Th. Henning , J. Kainulainen