Interaction of Interstellar Shocks with Dense Obstacles: Formation of “Bullets”

AbstractThe so-called cumulative effect take place in converging conical shock waves arising behind dense obstacles overtaken by incident interstellar shock. A significant part of energy of converging flow of matter swept-up by a radiative conical shock can be transferred to a dense jet-like ejection (“bullet”) directed along the cone axis. Possible applications of this effect for star-forming regions (e.g., OMC-1) and supernova remnants (e.g., Vela SNR) are discussed.

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Shocked Molecular Hydrogen from Star Forming Regions

Symposium - International Astronomical Union ◽

10.1017/s0074180900095371 ◽

1987 ◽

Vol 115 ◽

pp. 181-181 ◽

Cited By ~ 2

Author(s):

Adair P. Lane ◽

John Bally

Keyword(s):

Shock Waves ◽

High Velocity ◽

Molecular Hydrogen ◽

Near Infrared ◽

Young Stars ◽

Emission Lines ◽

Molecular Gas ◽

Star Forming ◽

Star Forming Regions ◽

Post Shock

Near infrared (2 micron) emission lines from molecular hydrogen provide a powerful probe of the morphology and energetics of outflows associated with stellar birth. The H2 emission regions trace the location of shock waves formed when the high velocity outflow from young stars encounters dense quiescent gas. Since H2 is the dominant coolant of the hot post-shock molecular gas, the H2 lines provide a measure of the fraction of the total mechanical luminosity radiated away from the cloud.

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MAGMO: polarimetry of 1720-MHz OH masers towards southern star-forming regions

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa167 ◽

2020 ◽

Vol 493 (1) ◽

pp. 199-233 ◽

Cited By ~ 2

Author(s):

C S Ogbodo ◽

J A Green ◽

J R Dawson ◽

S L Breen ◽

S A Mao ◽

...

Keyword(s):

Magnetic Field ◽

Star Formation ◽

Ground State ◽

Supernova Remnants ◽

Galactic Centre ◽

Galactic Magnetic Field ◽

Field Orientation ◽

Star Forming ◽

Star Forming Regions ◽

Methanol Masers

ABSTRACT From targeted observations of ground-state hydroxyl (OH) masers towards 702 Methanol Multibeam survey 6.7-GHz methanol masers, in the Galactic longitude range from 186° through the Galactic Centre to 20°, made as part of the ‘MAGMO’ (Mapping the Galactic Magnetic field through OH masers) project, we present the physical and polarization properties of the 1720-MHz OH maser transition, including the identification of Zeeman pairs. We present 10 new and 23 previously catalogued 1720-MHz OH maser sources detected towards star-forming regions (SFRs). In addition, we also detected 16 1720-MHz OH masers associated with supernova remnants and two sites of diffuse OH emission. Towards the 33 star formation masers, we identify 44 Zeeman pairs, implying magnetic field strengths ranging from −11.4 to +13.2 mG, and a median magnetic field strength of |BLOS| ∼ 6 mG. With limited statistics, we present the in situ magnetic field orientation of the masers and the Galactic magnetic field distribution revealed by the 1720-MHz transition. We also examine the association statistics of 1720-MHz OH SFR masers with other ground-state OH masers, excited-state OH masers, class I and class II methanol masers, and water masers, and compare maser positions with mid-infrared images of the parent SFRs. Of the 33 1720-MHz star formation masers, 10 are offset from their central exciting sources, and appear to be associated with outflow activity.

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An X-Ray View of Interacting Binaries Outside The Galaxy

International Astronomical Union Colloquium ◽

10.1017/s0252921100151693 ◽

2004 ◽

Vol 194 ◽

pp. 3-6

Author(s):

Andrea H. Prestwich

Keyword(s):

Supernova Remnants ◽

Luminosity Function ◽

Local Group ◽

Spiral Galaxies ◽

High Mass ◽

X Ray ◽

Star Forming ◽

Star Forming Regions ◽

Low Mass ◽

X Ray Binaries

AbstractChandra and XMM-Newton are revolutionizing our understanding of compact binaries in external galaxies, allowing us to study sources in detail in Local Group Galaxies and study populations in more distant systems. In M31 the X-ray luminosity function depends on the local stellar population in the sense that areas with active star formation have more high luminosity sources, and a higher overall source density (Kong. Di Stefano. Garcia, & Greiner 2003). This result is also true in galaxies outside the Local Group; starburst galaxies have flatter X-ray luminosity functions than do spiral galaxies which are in turn flatter than elliptical galaxies. These observational results suggest that the high end of the luminosity function in star forming regions is dominated by short-lived high mass X-ray binaries.In Chandra Cycle 2 we started a Large Project to survey a sample of 11 nearby (< 10Mpc) face-on spiral galaxies. We find that sources can be approximately classified on the basis of their X-ray color into low mass X-ray binaries, high mass X-ray binaries and supersoft sources. There is an especially interesting class of source that has X-ray colors softer (“redder”) than a typical low mass X-ray binary source, but not so extreme as supersoft sources. Most of these are probably X-ray bright supernova remnants, but some may be a new type of black hole accretor. Finally, when we construct a luminosity function of sources selecting only sources with low mass X-ray binary colors (removing soft sources) we find that there is a dip or break probably associated with the Eddington luminosity for a neutron star.

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Wind of a young massive star colliding with a supernova remnant shell

Journal of Physics Conference Series ◽

10.1088/1742-6596/2103/1/012013 ◽

2021 ◽

Vol 2103 (1) ◽

pp. 012013

Author(s):

D V Badmaev ◽

A M Bykov

Keyword(s):

Supernova Remnants ◽

Supernova Remnant ◽

Massive Star ◽

Compact Star ◽

Complex Structure ◽

Stellar Winds ◽

Star Forming ◽

Star Forming Regions ◽

Supernova Shell ◽

Favorable Conditions

Abstract The fast stellar winds of massive stars, along with supernovae, determine the dynamics within the star-forming regions. Within a compact star cluster, counterpropagating supersonic MHD shock flows associated with winds and supernova remnants can provide favorable conditions for efficient Fermi I particle acceleration up to energies > 10 PeV over a short timescale of several hundred years. To model the nonthermal spectra of such systems it is necessary to know the complex structure of colliding supersonic flows. In this paper using the PLUTO code we study on a subparsec scale a 2D MHD model of the collision of a core-collapse supernova remnant with a magnetized wind of a hot rotating O-star. As a result the detailed high resolution (~ 10−4 pc) maps of density, magnetic field, and temperature during the the wind - supernova shell interaction are presented.

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A search for OH 6 GHz maser emission towards southern supernova remnants

Proceedings of the International Astronomical Union ◽

10.1017/s174392130701304x ◽

2007 ◽

Vol 3 (S242) ◽

pp. 232-233 ◽

Cited By ~ 3

Author(s):

Korinne E. McDonnell ◽

Alan E. Vaughan ◽

Mark Wardle

Keyword(s):

Molecular Clouds ◽

Supernova Remnants ◽

Magellanic Clouds ◽

Maser Emission ◽

Star Forming ◽

Preliminary Results ◽

Star Forming Regions ◽

Maser Line

AbstractOH masers at 1720 MHz have proven to be excellent indicators of interactions between supernova remnants and molecular clouds. Recent calculations suggest that the 6049 MHz OH maser line is excited at higher column densities than for the 1720 MHz line. It is therefore a potentially valuable indicator of remnant-cloud interaction.We present preliminary results of a survey using the Parkes Methanol Multibeam receiver for 6049 MHz and 6035/6030 MHz OH masers towards 36 supernova remnants and four fields in the Large and Small Magellanic Clouds. While no 6049 MHz masers have been found, three new sites of 6035 and 6030 MHz OH maser emission have been discovered in star-forming regions.

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A review of maser polarization and magnetic fields

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307012549 ◽

2007 ◽

Vol 3 (S242) ◽

pp. 37-46 ◽

Cited By ~ 10

Author(s):

W. H. T. Vlemmings

Keyword(s):

Magnetic Field ◽

Supernova Remnants ◽

Massive Star ◽

Field Measurements ◽

Star Forming ◽

Physical Conditions ◽

Evolved Stars ◽

Star Forming Regions ◽

Fields Of Study ◽

The Magnetic Field

AbstractThrough polarization observations masers are unique probes of the magnetic field in a variety of different astronomical objects, with the different maser species tracing different physical conditions. In recent years maser polarization observations have provided insights in the magnetic field strength and morphology in, among others, the envelopes around evolved stars, Planetary Nebulae (PNe), massive star forming regions and supernova remnants. More recently, maser observations have even been used to determine the magnetic field in megamaser galaxies. This review will present an overview of maser polarization observations and magnetic field determinations of the last several years and discuss the implications of the magnetic field measurements for several important fields of study, such as aspherical PNe creation and massive star formation.

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OH maser emission in the THOR survey of the northern Milky Way

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935936 ◽

2019 ◽

Vol 628 ◽

pp. A90 ◽

Cited By ~ 7

Author(s):

H. Beuther ◽

A. Walsh ◽

Y. Wang ◽

M. Rugel ◽

J. Soler ◽

...

Keyword(s):

Northern Hemisphere ◽

Ground State ◽

Supernova Remnants ◽

Milky Way ◽

Diverse Range ◽

Maser Emission ◽

Star Forming ◽

Evolved Stars ◽

Star Forming Regions ◽

Expanding Shells

Context. OH masers trace diverse physical processes, from the expanding envelopes around evolved stars to star-forming regions or supernovae remnants. Providing a survey of the ground-state OH maser transitions in the northern hemisphere inner Milky Way facilitates the study of a broad range of scientific topics. Aims. We want to identify the ground-state OH masers at ∼18 cm wavelength in the area covered by The HI/OH/Recombination line survey of the Milky Way (THOR). We will present a catalogue of all OH maser features and their possible associated environments. Methods. The THOR survey covers longitude and latitude ranges of 14.°3 < l < 66.°8 and b < ± 1.°25. All OH ground state lines 2Π3/2 (J = 3/2) at 1612 (F = 1−2), 1665 (F = 1−1), 1667 (F = 2−2) and 1720 MHz (F = 2−1) have been observed, employing the Very Large Array (VLA) in its C configuration. The spatial resolution of the data varies between 12.5″ and 19″, the spectral resolution is 1.5 km s−1, and the rms sensitivity of the data is ∼10 mJy beam−1 per channel. Results. We identify 1585 individual maser spots (corresponding to single spectral features) distributed over 807 maser sites (regions of size ∼103 − 104 AU). Based on different criteria from spectral profiles to literature comparison, we try to associate the maser sites with astrophysical source types. Approximately 51% of the sites exhibit the double-horned 1612 MHz spectra typically emitted from the expanding shells of evolved stars. The separations of the two main velocity features of the expanding shells typically vary between 22 and 38 km s−1. In addition to this, at least 20% of the maser sites are associated with star-forming regions. While the largest fraction of 1720 MHz maser spots (21 out of 53) is associated with supernova remnants, a significant fraction of the 1720 MHz maser spots (17) are also associated with star-forming regions. We present comparisons to the thermal 13CO(1–0) emission as well as to other surveys of class II CH3OH and H2O maser emission. The catalogue attempts to present associations to astrophysical sources where available, and the full catalogue is available in electronic form. Conclusions. This OH maser catalogue presents a unique resource of stellar and interstellar masers in the northern hemisphere. It provides the basis for a diverse range of follow-up studies from envelopes around evolved stars to star-forming regions and Supernova remnants.

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Maser polarization and magnetic fields

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312006606 ◽

2012 ◽

Vol 8 (S287) ◽

pp. 31-40 ◽

Cited By ~ 2

Author(s):

W. H. T. Vlemmings

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Magnetic Field Strength ◽

Supernova Remnants ◽

Silicon Monoxide ◽

Star Forming ◽

Physical Conditions ◽

Star Forming Regions ◽

Theoretical Considerations ◽

The Magnetic Field

AbstractMaser polarization observations can reveal unique information on the magnetic field strength and structure for a large number of very different astronomical objects. As the different masers for which polarization is measured, such as silicon-monoxide, water, hydroxil and methanol, probe different physical conditions, the masers can even be used to determine for example the relation between magnetic field and density. In particular, maser polarization observations have improved our understanding of the magnetic field strength in, among others, the envelopes around evolved stars, Planetary Nebulae (PNe), massive star forming regions, supernova remnants and megamaser galaxies. This review presents an overview of maser polarization observations and magnetic field determinations of the last several years and discusses some of the theoretical considerations needed for a proper maser polarization analysis.

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