B. Radio Studies

Several regional surveys of southern HI made with the Argentine 100-m telescope were published (30.155.031). HI and other data were used by Dolidze (30.155. 044) to study the local distribution of gas and star forming regions. The Perseus arm region was the subject of an analogous study by Gerasimenko (34.155.139). Vallée (34.155.005) used rotation measure data from extragalactic sources in the direction of the Perseus arm to determine the magnetic field structure there and to constrain gravitational collapse theories of magnetic compression. HI in the direction of the Puppis window was surveyed by Stacy and Jackson (32.131.277) and used to study the turbulent characteristics of the interstellar medium. HI related to Gould“s Belt was studied by Pöppel and Olano (32.155.024, 33.155.030). Salter (34. 131.014) reviewed radio and other observations pertaining tc Loop I, the North Polar Spur, and considered the influence which this structure might have on the local medium.

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Searching for intergalactic star forming regions in Stephan’s Quintet with SITELLE

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935686 ◽

2019 ◽

Vol 629 ◽

pp. A102 ◽

Cited By ~ 1

Author(s):

S. Duarte Puertas ◽

J. Iglesias-Páramo ◽

J. M. Vilchez ◽

L. Drissen ◽

C. Kehrig ◽

...

Keyword(s):

Large Scale ◽

Dwarf Galaxy ◽

Three Dimensional ◽

Large Field ◽

North West ◽

Star Forming ◽

Spatially Resolved ◽

Star Forming Regions ◽

The North ◽

Spectral Ranges

Stephan’s Quintet (SQ), the prototypical compact group of galaxies in the local Universe, has been observed with the imaging Fourier transform spectrometer SITELLE, attached to the Canada-France-Hawaii-Telescope, to perform a deep search for intergalactic star-forming emission. In this paper we present the extended ionised gaseous structures detected and analyse their kinematical properties. The large field of view (11′ × 11′) and the spectral ranges of SITELLE have allowed a thorough study of the entire galaxy system, its interaction history and the main properties of the ionised gas. The observations have revealed complex three-dimensional strands in SQ seen for the first time, as well as the spatially resolved velocity field for a new SQ dwarf galaxy (M 82-like) and the detailed spectral map of NGC 7320c, confirming its AGN nature. A total of 175 SQ Hα emission regions have been found, 22 of which present line profiles with at least two kinematical components. We studied 12 zones and 28 sub-zones in the SQ system in order to define plausible physical spatial connections between its different parts in the light of the kinematical information gathered. In this respect we have found five velocity systems in SQ: (i) v = [5600−5900] km s−1 associated with the new intruder and the southern debris region; (ii) v = [5900−6100] km s−1, associated with the north starburst A and south starburst A and the strands connected to these zones; (iii) v = [6100−6600] km s−1, associated with the strands from the large-scale shock region (LSSR); (iv) v = [6600−6800] km s−1, associated with the young tidal tail, the starburst A (SQA), NGC 7319, and the NGC 7319 north lobe; and (v) v = [6800−7000] km s−1, associated with the strands seen connecting LSSR with SQA. We fail to detect ionised gas emission in the old tail, neither in the vicinity of NGC 7318A nor in NGC 7317, and the connection between NGC 7319 north lobe and SQA cannot be confirmed. Conversely, a clear gaseous bridge has been confirmed both spatially and kinematically between the LSSR zone and the NGC 7319 AGN nucleus. Finally, a larger scale, outer rim winding the NGC 7318B/A system clockwise north-west to south-east has been highlighted in continuum and in Hα. This structure may be reminiscent of a sequence of a previously proposed scenario for SQ a sequence of individual interactions.

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A New Molecular Core in L1641

Symposium - International Astronomical Union ◽

10.1017/s0074180900095012 ◽

1987 ◽

Vol 115 ◽

pp. 81-82

Author(s):

H. Takaba ◽

Y. Fukui

Keyword(s):

Star Formation ◽

Emission Line ◽

Hot Spots ◽

Orion Nebula ◽

Dark Cloud ◽

Star Forming ◽

Star Forming Regions ◽

The North ◽

Molecular Core ◽

A Site

L1641 is a large dark cloud which extends 6.3 degree2 to the south of the Orion nebula (Lynds 1962). This region contains a reflection nebula, NGC 1999, several emission line stars and Herbig-Haro objects and is thought to be a site of on-going star formation. A CO(J = 1-0) map obtained with the Nagoya 1.5 m telescope (Takano 1983) revealed that CO hot spots extend further to the north by ∼ 30′ from NGC 1999. This suggests that L1641 may contain other regions of recent star formation. Therefore, we have mapped the L1641 cloud to investigate if there are other star-forming regions in it.

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Star-Forming Regions in the SMC

Proceedings of the International Astronomical Union ◽

10.1017/s1743921306006764 ◽

2006 ◽

Vol 2 (S235) ◽

pp. 311-311

Author(s):

I. Gonidakis ◽

E. Livanou ◽

E. Kontizas ◽

U. Klein ◽

M. Kontizas ◽

...

Keyword(s):

Star Formation ◽

Starburst Galaxies ◽

Radio Continuum ◽

Spectral Energy ◽

High Concentration ◽

Star Forming ◽

Star Forming Regions ◽

The North ◽

Star Formation Activity ◽

West Part

AbstractSMC has been going through an active star formation epoch, especially during the last 0.2 Gyr when the close encounter with the LMC occured. Our goal is to detect regions dominated by early-type stars and gas and examine their behaviour at different wavelengths. Spectral energy distributions, a colour-magnitude diagram and a two-colour diagram from IRAS data (Bontekoe, Koperet & Kester (1994); Bontekoe, Kester, Stanimirović, et al. (1999)) for these regions were used in order to compare their properties with those of starburst galaxies (Helou (1986); Lehnert & Heckman (1995)). We have selected 50 stellar complexes with increased 100-μm IRAS flux, with detetected emission in all IRAS bands and/or high concentration of young stars. Ranking them by size (Maragoudaki, Kontizas, Kontizas, et al. (1998)), a total of what we call 24 aggregates, 23 complexes and 3 super-complexes were found. Radio continuum maps at 8.6-GHz (Haynes, Murray, Klein, et al. (1986)) and the CO (1→0) line (Mizuno, Rubio, Mizuno, et al. (2001)) were also correlated with the map of the complexes. Only 8 of them show enhanced star formation activity according to their IR properties and 8.6-GHz map, however, none of them resembles the IR behaviour of starburst regions found in the LMC and starburst galaxies (Livanou, Kontizas, Gonidakis, et al. (2006)). The south-west part of the “bar” has the most diverse intensity of star formation, with CO emission coincident with the largest structure. In the north-eastern end of the “bar”, star formation is likely to have commenced in the recent past, with molecular gas being abundant in this region. Ongoing and future star formation are revealed in the wing, while it appears to have ceased in the central “bar”.

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The Nuclear Ring in the Barred Spiral Galaxy IC 4933

Publications of the Astronomical Society of Australia ◽

10.1071/as09016 ◽

2010 ◽

Vol 27 (1) ◽

pp. 56-63 ◽

Cited By ~ 5

Author(s):

Stuart D. Ryder ◽

Samuel M. Illingworth ◽

Robert G. Sharp ◽

Catherine L. Farage

Keyword(s):

Spiral Galaxy ◽

Near Infrared ◽

Infrared Imaging ◽

Star Formation History ◽

Star Forming ◽

Star Forming Regions ◽

The North ◽

Contact Points ◽

Nuclear Ring ◽

Barred Spiral Galaxy

AbstractWe present infrared imaging from IRIS2 on the Anglo–Australian Telescope that shows the barred spiral galaxy IC 4933 has not just an inner ring encircling the bar, but also a star-forming nuclear ring 1.5 kpc in diameter. Imaging in the u′ band with GMOS on Gemini South confirms that this ring is not purely an artifact due to dust. Optical and near-infrared colours alone however cannot break the degeneracy between age, extinction, and burst duration that would allow the star formation history of the ring to be unraveled. Integral field spectroscopy with the GNIRS spectrograph on Gemini South shows the equivalent width of the Paβ line to peak in the north and south quadrants of the ring, indicative of a bipolar azimuthal age gradient around the ring. The youngest star-forming regions do not appear to correspond to where we expect to find the contact points between the offset dust lanes and the nuclear ring unless the nuclear ring is oval in shape, causing the contact points to lead the bar by more than 90°.

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Survey observations of large-scale molecular outflows associated with intermediate-mass protostar candidates in the OMC-2/3 region

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307002670 ◽

2006 ◽

Vol 2 (S237) ◽

pp. 479-479

Author(s):

Satoko Takahashi ◽

Y. Shimajiri ◽

S. Takakuwa ◽

M. Saito ◽

R. Kawabe

Keyword(s):

Large Scale ◽

Driving Mechanism ◽

Mass Star ◽

Intermediate Mass ◽

Star Forming ◽

Molecular Outflows ◽

Star Forming Regions ◽

North East ◽

The North ◽

Molecular Outflow

AbstractWe have newly performed millimeter- and submillimeter-wave observations in the nearest GMC: the Orion Molecular Cloud -2/3 region (OMC-2/3). Here, we report results of our large-scale (22' × 14') outflow survey with the Atacama Submillimeter Telescope Experiment (ASTE) in the CO(3-2) emission. The OMC-2/3 region is one of the famous intermediate-mass star-forming regions and harbors several sources diagnosed as Class0 protostars (Chini et al. 1997). With the intensive ASTE observations, we totally identified the 8 clear, 5 probable and 6 marginal outflows in OMC-2/3. 8 clear outflows from them, MMS 2, MMS 5, MMS7, MMS9, FIR-2, FIR 3, VLA 13, and FIR 6b are associated with mm and SPITZER 24 μm sources. The others are more or less complicated, and two of which, VLA 13 and FIR 6, are newly identified. We found the interaction between the molecular outflows and the dust condensations at least in four regions. In addition, we confirmed the increment of the velocity width of the dense gas toward some of these condensations (i.e. at the termination of the outflow lobes). These results suggest that (i) the interaction between the outflows and the dense condensation occurs commonly in the OMC-2/3 region, (ii) the dense condensations in this region are compressed ubiquitously by these outflows and are receiving a part of the momentum from them. Particularly, one of the strongest millimeter sources, and hence protostar candidates, FIR4, is strongly compressed by a molecular outflow driven by FIR3 located at the north-east of FIR 4. These results suggest that the molecular outflows play an important role in the formation and evolution of stars and that the outflows are a driving mechanism of turbulence in the OMC-2/3 region.

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Faraday Depolarization Effects in Spiral Galaxies

Galaxies ◽

10.3390/galaxies7010015 ◽

2019 ◽

Vol 7 (1) ◽

pp. 15 ◽

Cited By ~ 1

Author(s):

Mami Machida ◽

Takuya Akahori ◽

Kenji Nakamura ◽

Hiroyuki Nakanishi ◽

Marijke Haverkorn

Keyword(s):

Magnetic Fields ◽

Galactic Center ◽

Azimuthal Angle ◽

Field Structure ◽

Stokes Parameters ◽

Structural Formation ◽

Star Forming ◽

Star Forming Regions ◽

Rotation Measure ◽

The Universe

Magnetic fields in the universe play an essential role in observations of the radio synchrotron continuum; however, we do not know enough about them, either observationally or theoretically. We are interested in galactic magnetic fields because they affect the structural formation of galaxies in terms of star-forming regions, spiral arms, and threads at the galactic center. To clarify the importance of magnetic fields, we carried out numerical simulations of the galactic gaseous disk with magnetic fields. We also calculated observables, such as the rotation measure and Stokes parameters, from the results of numerical simulation. FD maps and intensity maps have been reported, and the relation between azimuthal angle and FD has been shown to depend on the inclination of the observer. Furthermore, it has been shown that a polarized intensity below 800 MHz reflects field structure in the halo region, although the intensity is weak. The present paper summarizes the effects of Faraday depolarization and the relation between magnetic-field structure and Stokes parameters.

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The VLT/MUSE view of the central galaxy in Abell 2052

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732022 ◽

2018 ◽

Vol 612 ◽

pp. A19 ◽

Cited By ~ 6

Author(s):

Barbara Balmaverde ◽

Alessandro Capetti ◽

Alessandro Marconi ◽

Giacomo Venturi

Keyword(s):

Interstellar Medium ◽

Line Emission ◽

Emission Lines ◽

Expansion Velocity ◽

Direct Estimate ◽

X Ray ◽

Star Forming ◽

Star Forming Regions ◽

The North ◽

Integral Field Spectrograph

We report observations of the radio galaxy 3C 317 (at z = 0.0345) located at the center of the Abell cluster A2052, obtained with the VLT/MUSE integral field spectrograph. The Chandra images of this cluster show cavities in the X-ray emitting gas, which were produced by the expansion of the radio lobes inflated by the active galactic nucleus (AGN). Our exquisite MUSE data show with unprecedented detail the complex network of line emitting filaments enshrouding the northern X-ray cavity. We do not detect any emission lines from the southern cavity, with a luminosity asymmetry between the two regions higher than ~75. The emission lines produced by the warm phase of the interstellar medium (WIM) enable us to obtain unique information on the properties of the emitting gas. We find dense gas (up to 270 cm−3) that makes up part of a global quasi spherical outflow that is driven by the radio source, and obtain a direct estimate of the expansion velocity of the cavities (265 km s−1). The emission lines diagnostic rules out ionization from the AGN or from star-forming regions, suggesting instead ionization from slow shocks or from cosmic rays. The striking asymmetric line emission observed between the two cavities contrasts with the less pronounced differences between the north and south sides in the hot gas; this represents a significant new ingredient for our understanding of the process of the exchange of energy between the relativistic plasma and the external medium. We conclude that the expanding radio lobes displace the hot tenuous phase of the interstellar medium (ISM), but also impact the colder and denser ISM phases. These results show the effects of the AGN on its host and the importance of radio mode feedback.

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