Mid‐Infrared Diagnostics of Starburst Galaxies: Clumpy, Dense Structures in Star‐Forming Regions in the Antennae (NGC 4038/4039)

Subarcsecond radio and infrared observations reveal a class of luminous, obscured, optically thick HII regions associated with extremely large young clusters in nearby starburst galaxies. VLA images show bright radio nebulae with ne ∼ 104 cm−3, densities characteristic of young Galactic compact HII regions. Excitation of the nebulae requires the presence of several thousand O stars within regions of 1-10 pc extent, corresponding to clusters containing 105–106 stars. The compact nebulae are also bright in the mid-infrared, and can for significant fractions of not only the total IR luminosity, but also the total bolometric luminosity, of the parent galaxies. The prototype for these “supernebulae” is the large, obscured cluster in the dwarf galaxy NGC 5253.

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A MULTIWAVELENGTH STUDY OF YOUNG MASSIVE STAR-FORMING REGIONS. III. MID-INFRARED EMISSION

The Astrophysical Journal ◽

10.1088/0004-637x/698/1/488 ◽

2009 ◽

Vol 698 (1) ◽

pp. 488-501 ◽

Cited By ~ 6

Author(s):

Esteban F. E. Morales ◽

Diego Mardones ◽

Guido Garay ◽

Kate J. Brooks ◽

Jaime E. Pineda

Keyword(s):

Massive Star ◽

Infrared Emission ◽

Mid Infrared ◽

Star Forming ◽

Star Forming Regions

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A radio polarimetric study to disentangle AGN activity and star formation in Seyfert galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2473 ◽

2020 ◽

Vol 499 (1) ◽

pp. 334-354

Author(s):

Biny Sebastian ◽

P Kharb ◽

C P O’Dea ◽

J F Gallimore ◽

S A Baum

Keyword(s):

Star Formation ◽

Radio Emission ◽

Seyfert Galaxies ◽

Starburst Galaxies ◽

Shock Acceleration ◽

Very Large Array ◽

Star Forming ◽

Array Configuration ◽

Star Forming Regions ◽

Tentative Evidence

ABSTRACT To understand the origin of radio emission in radio-quiet active galactic nucleus (AGN) and differentiate between the contributions from star formation, AGN accretion, and jets, we have observed a nearby sample of Seyfert galaxies along with a comparison sample of starburst galaxies using the Expanded Very Large Array (EVLA) in full-polarization mode in the B-array configuration. The radio morphologies of the Seyfert galaxies show lobe/bubble-like features or prominent cores in radio emission, whereas the starburst galaxies show radio emission spatially coincident with the star-forming regions seen in optical images. There is tentative evidence that Seyferts tend to show more polarized structures than starburst galaxies at the resolution of our observations. We find that unlike a sample of Seyfert galaxies hosting kilo-parsec scale radio (KSR) emission, starburst galaxies with superwinds do not show radio-excess compared to the radio–FIR correlation. This suggests that shock acceleration is not adequate to explain the excess radio emission seen in Seyferts and hence most likely have a jet-related origin. We also find that the [O iii] luminosity of the Seyferts is correlated with the off-nuclear radio emission from the lobes, whereas it is not well correlated with the total emission which also includes the core. This suggests strong jet–medium interaction, which in turn limits the jet/lobe extents in Seyferts. We find that the power contribution of AGN jet, AGN accretion, and star formation is more or less comparable in our sample of Seyfert galaxies. We also find indications of episodic AGN activity in many of our Seyfert galaxies.

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UCHII regions in the Antennae

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307002645 ◽

2006 ◽

Vol 2 (S237) ◽

pp. 476-476

Author(s):

L. Snijders ◽

L. J. Kewley ◽

P. P. van der Werf ◽

B. R. Brandl

Keyword(s):

Emission Line ◽

Spatial Resolution ◽

Average Density ◽

Physical Characteristics ◽

Stellar Clusters ◽

Mid Infrared ◽

Infrared Observations ◽

Star Forming ◽

Compact Material ◽

Star Forming Regions

AbstractWe explore the physical characteristics of young stellar clusters in the Antennae by combining recent ground- and space-based mid-infrared observations with a newly developed set of diagnostic diagrams. Spitzer data give an overview of the star-forming regions extending over hundreds of parsecs, showing a dominant diffuse ISM component with a density of 102 cm−3 plus a small fraction of very compact material (106 cm−3). With its higher spatial resolution VISIR gives a close-up view of the latter component. Its emission line ratios suggest that these regions are fundamentally different from local star-forming regions. Instead of having small isolated UCHII regions, as in local star-forming regions, the average density of the medium of the whole region falls in the (ultra)compact regime, exceeding 104 cm−3 over tens of parsecs.

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Drama of HII regions: Clustered and Triggered Star Formation

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315008935 ◽

2015 ◽

Vol 12 (S316) ◽

pp. 129-130

Author(s):

Jin-Zeng Li ◽

Jinghua Yuan ◽

Hong-Li Liu ◽

Yuefang Wu ◽

Ya-Fang Huang

Keyword(s):

Star Formation ◽

Hii Regions ◽

Radio Telescopes ◽

Physical Status ◽

Mid Infrared ◽

Star Forming ◽

Star Forming Regions ◽

Dense Cores ◽

Compressed Gas ◽

Multi Wavelength

AbstractIn order to understand the star formation process under the influence of H ii regions, we have carried out extensive investigations to well selected star-forming regions which all have been profoundly affected by existing massive O type stars. On the basis of multi-wavelength data from mid-infrared to millimeter collected using Spitzer, Herschel, and ground based radio telescopes, the physical status of interstellar medium and star formation in these regions have been revealed. In a relatively large infrared dust bubble, active star formation is undergoing and the shell is still expanding. Signs of compressed gas and triggered star formation have been tentatively detected in a relatively small bubble. The dense cores in the Rosette Molecular Complex detected at 1.1 mm using SMA have been speculated to have a likely triggered origin according to their spatial distribution. Although some observational results have been obtained, more efforts are necessary to reach trustworthy conclusions.

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Optical and mid-infrared neon abundance determinations in star-forming regions

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stt610 ◽

2013 ◽

Vol 432 (3) ◽

pp. 2512-2528 ◽

Cited By ~ 11

Author(s):

Oli L. Dors ◽

Guillermo F. Hägele ◽

Mónica V. Cardaci ◽

Enrique Pérez-Montero ◽

Ângela C. Krabbe ◽

...

Keyword(s):

Mid Infrared ◽

Star Forming ◽

Star Forming Regions

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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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