Giant Molecular Clouds in the Spiral Arm of Ic 342

Hirota, Akihiko; Kuno, Nario; Sato, Naoko; Nakanishi, Hiroyuki; Tosaki, Tomoka; Saito, Kazuo

doi:10.1088/0004-637x/737/1/40

Cited by 34 publications

(43 citation statements)

References 84 publications

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“…Analogies for the GMA formation processes could be M 51 (Koda et al 2009) or IC 342 (Hirota et al 2011, see also Sect. 4.3.3 for a more detailed comparison with other GMAbearing galaxies).…”

Section: Formation Of Gmas In the Ringmentioning

confidence: 99%

“…orbital crowding) in the mergers take place that lead to the collisional coagulation of individual GMCs. These cloud-cloud collisions could also trigger the onset of star formation (Scoville et al 1986;Tan 2000) − the dissipation of excess kinetic energy during the collisions is a prerequisite for star formation (Hirota et al 2011). Observations at higher angular resolution and sensitivity are necessary to resolve the molecular gas properties of the low surface brightness GMCs in the umbilical cords.…”

Section: Formation Of Gmas In the Ringmentioning

confidence: 99%

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The NGC 1614 interacting galaxy

König

Aalto

Müller

et al. 2013

A&A

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Minor mergers frequently occur between giant and gas-rich low-mass galaxies and can provide significant amounts of interstellar matter to refuel star formation and power active galactic nuclei (AGN) in the giant systems. Major starbursts and/or AGN result when fresh gas is transported and compressed in the central regions of the giant galaxy. This is the situation in the starburst minor merger NGC 1614, whose molecular medium we explore at half-arcsecond angular resolution through our observations of 12 CO (2−1) emission using the Submillimeter Array (SMA). We compare our 12 CO (2−1) maps with optical and Paα, Hubble Space Telescope and high angular resolution radio continuum images to study the relationships between dense molecular gas and the NGC 1614 starburst region. The most intense 12 CO emission occurs in a partial ring with ∼230 pc radius around the center of NGC 1614, with an extension to the northwest into the dust lane that contains diffuse molecular gas. We resolve ten giant molecular associations (GMAs) in the ring, which has an integrated molecular mass of ∼8 × 10 8 M . Our interferometric observations filter out a large part of the 12 CO (1−0) emission mapped at shorter spacings, indicating that most of the molecular gas is diffuse and that GMAs only exist near and within the circumnuclear ring. The molecular ring is uneven with most of the mass on the western side, which also contains GMAs extending into a pronounced tidal dust lane. The spatial and kinematic patterns in our data suggest that the northwest extension of the ring is a cosmic umbilical cord that is feeding molecular gas associated with the dust lane and tidal debris into the nuclear ring, which contains the bulk of the starburst activity. The astrophysical process for producing a ring structure for the final resting place of accreted gas in NGC 1614 is not fully understood, but the presence of numerous GMAs suggests an orbit-crowding or resonance phenomenon. There is some evidence that star formation is progressing radially outward within the ring, indicating that a self-triggering mechanism may also affect star formation processes. The net result of this merger therefore very likely increases the central concentration of stellar mass in the NGC 1614 remnant giant system.

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Section: Formation Of Gmas In the Ringmentioning

confidence: 99%

Section: Formation Of Gmas In the Ringmentioning

confidence: 99%

The NGC 1614 interacting galaxy

König

Aalto

Müller

et al. 2013

A&A

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“…Using either 12 CO(J = 1 → 0) or 12 CO(J = 2 → 1) to trace the molecular gas distribution, wide-field surveys covering a significant fraction of a galactic disk with a linear resolution of ∼50 pc or better have recently been completed for M31, M33, IC10, M64, the Magellanic Clouds, IC342, NGC 6822, and NGC 6946 Engargiola et al 2003;Gardan et al 2007;Gratier et al 2012; Leroy et al 2006;Rosolowsky & Blitz 2005;Fukui et al 2008;Mizuno et al 2001;Wong et al 2011;Muller et al 2010;Gratier et al 2010;Hirota et al 2011;Donovan Meyer et al 2012;Rebolledo et al 2012). These surveys have found some evidence that the properties of molecular clouds vary with environment and their level of star formation activity.…”

Section: Introductionmentioning

confidence: 99%

“…These surveys have found some evidence that the properties of molecular clouds vary with environment and their level of star formation activity. In IC342, the Large Magellanic Cloud (LMC) and M33, GMCs with signs of ongoing massive star formation, are found to exhibit higher peak CO brightness temperatures than non-star-forming clouds (Hirota et al 2011;Hughes et al 2010;Gratier et al 2012). Notes.…”

Section: Introductionmentioning

confidence: 99%

“…b References for galaxy inclination: (1) van der Marel & Cioni 2001; (2) Paturel et al 2003 (HyperLeda); (3) Colombo et al 2013. c The reference for galaxy types and magnitudes is de Vaucouleurs et al (1991). d References for characteristic metallicity: (1) Marble et al 2010; (2) Rosolowsky & Simon 2008; (3) Moustakas et al 2010. Other examples include larger linewidths for molecular structures without high-mass star formation (IC342 and M83; Hirota et al 2011;Muraoka et al 2009) and in the central regions of galaxies (the Galactic center and NGC 6946; Oka et al 2001;Donovan Meyer et al 2012), a decrease in CO brightness at large galactocentric radii (the Milky Way and M33; Heyer et al 2001;Gratier et al 2012), higher mass surface densities in highpressure environments (e.g., M64; Rosolowsky & Blitz 2005), and a lower CO surface brightness and narrower linewidths for GMCs in dwarf galaxies (e.g., B08; Rubio et al 1993;Muller et al 2010;Hughes et al 2010;Gratier et al 2010). Yet much of the apparent galaxy-to-galaxy variation in GMC properties could be due to the disparate sensitivity and resolution of the observations and/or methodological differences (as noted by, e.g., Sheth et al 2008).…”

Section: Introductionmentioning

confidence: 99%

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A Comparative Study of Giant Molecular Clouds in M51, M33, and the Large Magellanic Cloud

Hughes

Meidt

Colombo

et al. 2013

ApJ

204

305

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We compare the properties of giant molecular clouds (GMCs) in M51 identified by the Plateau de Bure Interferometer Whirlpool Arcsecond Survey with GMCs identified in wide-field, high-resolution surveys of CO emission in M33 and the Large Magellanic Cloud (LMC). We find that GMCs in M51 are larger, brighter, and have higher velocity dispersions relative to their sizes than equivalent structures in M33 and the LMC. These differences imply that there are genuine variations in the average mass surface density Σ H 2 of the different GMC populations. To explain this, we propose that the pressure in the interstellar medium surrounding the GMCs plays a role in regulating their density and velocity dispersion. We find no evidence for a correlation between size and linewidth in M51, M33, or the LMC when the CO emission is decomposed into GMCs, although moderately robust correlations are apparent when regions of contiguous CO emission (with no size limitation) are used. Our work demonstrates that observational bias remains an important obstacle to the identification and study of extragalactic GMC populations using CO emission, especially in molecule-rich galactic environments.

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Star clusters in evolving galaxies

Renaud

2018

New Astronomy Reviews

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Their ubiquity and extreme densities make star clusters probes of prime importance of galaxy evolution. Old globular clusters keep imprints of the physical conditions of their assembly in the early Universe, and younger stellar objects, observationally resolved, tell us about the mechanisms at stake in their formation. Yet, we still do not understand the diversity involved: why is star cluster formation limited to 10 5 M objects in the Milky Way, while some dwarf galaxies like NGC 1705 are able to produce clusters 10 times more massive? Why do dwarfs generally host a higher specific frequency of clusters than larger galaxies? How to connect the present-day, often resolved, stellar systems to the formation of globular clusters at high redshift? And how do these links depend on the galactic and cosmological environments of these clusters? In this review, I present recent advances on star cluster formation and evolution, in galactic and cosmological context. The emphasis is put on the theory, formation scenarios and the effects of the environment on the evolution of the global properties of clusters. A few open questions are identified.

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Giant Molecular Clouds in the Spiral Arm of Ic 342

Cited by 34 publications

References 84 publications

The NGC 1614 interacting galaxy

The NGC 1614 interacting galaxy

A Comparative Study of Giant Molecular Clouds in M51, M33, and the Large Magellanic Cloud

Star clusters in evolving galaxies

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