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Related papers: Magnetic fields and the location of the PDR

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Magnetic pressure has long been known to dominate over gas pressure in atomic and molecular regions of the interstellar medium. Here I review several recent observational studies of the relationships between the H^+, H^0 and H_2 regions in…

Astrophysics of Galaxies · Physics 2009-11-13 Gary J. Ferland

The southwestern (SW) part of the Galactic H II region M17 contains an obscured ionization front that is most easily seen at infrared and radio wavelengths. It is nearly edge-on, thus offering an excellent opportunity to study the way in…

The emission line regions of starburst galaxies and active nuclei reveal a wealth of spectroscopic information. A unified picture of the relationship between ionized, atomic, and molecular gas makes it possible to better understand these…

Astrophysics · Physics 2008-11-26 N. P. Abel , G. J. Ferland

We present the results of radiation-magnetohydrodynamic simulations of the expansion of HII regions and surrounding photodissociation regions in turbulent, magnetised, molecular clouds on scales of up to 4 parsecs, including the effects of…

Astrophysics of Galaxies · Physics 2015-05-27 S. J. Arthur , W. J. Henney , G. Mellema , F. De Colle , E. Vázquez-Semadeni

Previous work has shown the Orion Bar to be an interface between ionized and molecular gas, viewed roughly edge on, which is excited by the light from the Trapezium cluster. Much of the emission from any star-forming region will originate…

Astrophysics · Physics 2011-02-11 E. W. Pellegrini , J. A. Baldwin , G. J. Ferland , Gargi Shaw , S. Heathcote

We present observational results of the thermal dust continuum emission and its linear polarization in one of the nearest massive star-forming sites Orion BN/KL in Orion Molecular Cloud-1. The observations were carried out with the…

Astrophysics of Galaxies · Physics 2015-05-19 Ya-Wen Tang , Paul T. P. Ho , Patrick M. Koch , Ramprasad Rao

The Orion Bar is one of the nearest and best-studied photodissociation or photon-dominated regions (PDRs). Observations reveal the presence of H2 lines from vibrationally or rotationally excited upper levels that suggest warm gas…

Astrophysics of Galaxies · Physics 2009-08-05 Gargi Shaw , G. J. Ferland , W. J. Henney , P. C. Stancil , N. P. Abel , E. W. Pellegrini , J. A. Baldwin , P. A. M. van Hoof

Magnetic fields are ubiquitous and essential in star formation. In particular, their role in regulating formation of stars across diverse environments like HII regions needs to be well understood. In this study, we present magnetic field…

Astrophysics of Galaxies · Physics 2021-04-28 R. Devaraj , D. P. Clemens , L. K. Dewangan , A. Luna , T. P. Ray , J. Mackey

Bright-rimmed clouds (BRCs) are formed at the periphery of H$~$II regions as the radiation from the central star interacts with dense gas. The ionization and resulting compression of the clouds may lead to cloud disruption causing secondary…

Astrophysics of Galaxies · Physics 2016-11-10 A. Soam , G. Maheswar , Chang Won Lee , S. Neha , B-G Andersson

Bright-rimmed clouds form on the edges of H II regions affected by the high energy radiation from a central ionizing source. The UV radiation from the ionizing source results in compression and ionization causing either cloud disruption or…

Astrophysics of Galaxies · Physics 2018-04-25 Archana Soam , G. Maheswar , Chang Won Lee , S. Neha , Kee-Tae Kim

We present an optical polarimetric study of a nearby star-forming region, Lambda-Orionis, to map plane-of-the-sky magnetic field geometry to understand the magnetized evolution of the HII region and associated small molecular clouds. We…

Astrophysics of Galaxies · Physics 2024-09-18 Sharma Neha , Archana Soam , G. Maheswar

Magnetic fields of molecular clouds in the Central Molecular Zone (CMZ) have been relatively underobserved at sub-parsec resolution. Here we report JCMT/POL2 observations of polarized dust emission in the CMZ, which reveal magnetic field…

In an attempt to probe the magnetic field morphology near the massive young star Orion-IRc2, we mapped the linear polarization of its J=2-1 SiO masers, in both the v=0 and v=1 vibrational levels, with 0.5 arcsec resolution. The intense v=1…

Astrophysics · Physics 2009-11-10 R. L. Plambeck , M. C. H. Wright , R. Rao

New visible and K-band polarization measurements on stars surrounding molecular clouds in Orion A and stars in the BN vicinity are presented. Our results confirm that magnetic fields located inside the Orion A molecular clouds and in their…

Astrophysics of Galaxies · Physics 2015-05-30 Frédérick Poidevin , Pierre Bastien , Terry J. Jones

We present the stability analysis of two regions, OMC-3 and OMC-4, in the massive and long molecular cloud complex of Orion A. We obtained $214~\mu$m HAWC+/SOFIA polarization data, and we make use of archival data for the column density and…

Astrophysics of Galaxies · Physics 2022-06-29 Pak Shing Li , Enrique Lopez-Rodriguez , Archana Soam , Richard I. Klein

In massive stars, magnetic fields are thought to confine the outflowing radiatively-driven wind, resulting in X-ray emission that is harder, more variable and more efficient than that produced by instability-generated shocks in non-magnetic…

Astrophysics · Physics 2008-09-29 V. Petit , G. A. Wade , L. Drissen , T. Montmerle , E. Alecian

Recent high-angular-resolution (up to 0.7") dust polarization observations toward star forming regions are summarized. With the Sub-Millimeter Array, the emission from the dense structures is traced and resolved. The detected magnetic field…

Astrophysics of Galaxies · Physics 2012-02-22 Ya-Wen Tang , Patrick M. Koch , Paul T. P. Ho

Measuring interstellar magnetic fields is extremely important for understanding their role in different evolutionary stages of interstellar clouds and of star formation. However, detecting the weak field is observationally challenging. We…

Astrophysics of Galaxies · Physics 2021-01-06 Atanu Koley , Nirupam Roy , Karl M. Menten , Arshia M. Jacob , Thushara G. S. Pillai , Michael R. Rugel

Massive stars are formed in molecular clouds, and produce H II regions when they evolve onto the main sequence. The expansion of H II region can both suppress and promote star formation in the vicinity. M17 H II region is a giant cometary H…

Astrophysics of Galaxies · Physics 2023-06-22 Feng-Yao Zhu , Junzhi Wang , Yaoting Yan , Qing-Feng Zhu , Juan Li

The magnetic structure in the Galactic disk, the Galactic center and the Galactic halo can be delineated more clearly than ever before. In the Galactic disk, the magnetic structure has been revealed by starlight polarization within 2 or 3…

Astrophysics of Galaxies · Physics 2009-11-13 J. L. Han
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