Multi-scale analysis of the Monoceros OB 1 star-forming region

Context. We started a multi-scale analysis of star formation in G202.3+2.5, an intertwined filamentary sub-region of the Monoceros OB1 molecular complex, in order to provide observational constraints on current theories and models that attempt to explain star formation globally. In the first paper (Paper I), we examined the distributions of dense cores and protostars and found enhanced star formation activity in the junction region of the filaments. Aims. In this second paper, we aim to unveil the connections between the core and filament evolutions, and between the filament dynamics and the global evolution of the cloud. Methods. We characterise the gas dynamics and energy balance in different parts of G202.3+2.5 using infrared observations from the Herschel and WISE telescopes and molecular tracers observed with the IRAM 30-m and TRAO 14-m telescopes. The velocity field of the cloud is examined and velocity-coherent structures are identified, characterised, and put in perspective with the cloud environment. Results. Two main velocity components are revealed, well separated in radial velocities in the north and merged around the location of intense N2H+ emission in the centre of G202.3+2.5 where Paper I found the peak of star formation activity. We show that the relative position of the two components along the sightline, and the velocity gradient of the N2H+ emission imply that the components have been undergoing collision for ~105 yr, although it remains unclear whether the gas moves mainly along or across the filament axes. The dense gas where N2H+ is detected is interpreted as the compressed region between the two filaments, which corresponds to a high mass inflow rate of ~1 × 10−3 M⊙ yr−1 and possibly leads to a significant increase in its star formation efficiency. We identify a protostellar source in the junction region that possibly powers two crossed intermittent outflows. We show that the H II region around the nearby cluster NCG 2264 is still expanding and its role in the collision is examined. However, we cannot rule out the idea that the collision arises mostly from the global collapse of the cloud. Conclusions. The (sub-)filament-scale observables examined in this paper reveal a collision between G202.3+2.5 sub-structures and its probable role in feeding the cores in the junction region. To shed more light on this link between core and filament evolutions, one must characterise the cloud morphology, its fragmentation, and magnetic field, all at high resolution. We consider the role of the environment in this paper, but a larger-scale study of this region is now necessary to investigate the scenario of a global cloud collapse.

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Nobeyama 45 m mapping observations toward the nearby molecular clouds Orion A, Aquila Rift, and M17: Project overview

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/psz057 ◽

2019 ◽

Vol 71 (Supplement_1) ◽

Cited By ~ 8

Author(s):

Fumitaka Nakamura ◽

Shun Ishii ◽

Kazuhito Dobashi ◽

Tomomi Shimoikura ◽

Yoshito Shimajiri ◽

...

Keyword(s):

Star Formation ◽

Molecular Clouds ◽

Column Density ◽

Angular Resolution ◽

High Mass ◽

Mass Star ◽

Calibration Data ◽

Star Forming ◽

Star Formation Activity ◽

Scientific Results

Abstract We carried out mapping observations toward three nearby molecular clouds, Orion A, Aquila Rift, and M 17, using a new 100 GHz receiver, FOREST, on the Nobeyama 45 m telescope. We describe the details of the data obtained such as intensity calibration, data sensitivity, angular resolution, and velocity resolution. Each target contains at least one high-mass star-forming region. The target molecular lines were 12CO (J = 1–0), 13CO (J = 1–0), C18O (J = 1–0), N2H+ (J = 1–0), and CCS (JN = 87–76), with which we covered the density range of 102 cm−3 to 106 cm−3 with an angular resolution of ∼20″ and a velocity resolution of ∼0.1 km s−1. Assuming the representative distances of 414 pc, 436 pc, and 2.1 kpc, the maps of Orion A, Aquila Rift, and M17 cover most of the densest parts with areas of about 7 pc × 15 pc, 7 pc × 7 pc, and 36 pc × 18 pc, respectively. On the basis of the 13CO column density distribution, the total molecular masses are derived to be $3.86 \times 10^{4}\, M_\odot$, $2.67 \times 10^{4}\, M_{\odot }$, and $8.1\times 10^{5}\, M_{\odot }$ for Orion A, Aquila Rift, and M17, respectively. For all the clouds, the H2 column density exceeds the theoretical threshold for high-mass star formation of ≳ 1 g cm−2 only toward the regions which contain current high-mass star-forming sites. For other areas, further mass accretion or dynamical compression would be necessary for future high-mass star formation. This is consistent with the current star formation activity. Using the 12CO data, we demonstrate that our data have enough capability to identify molecular outflows, and for the Aquila Rift we identify four new outflow candidates. The scientific results will be discussed in detail in separate papers.

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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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Multi-scale analysis of snow dynamics at the southern margin of the North American continental snow distribution

Remote Sensing of Environment ◽

10.1016/j.rse.2015.08.028 ◽

2015 ◽

Vol 169 ◽

pp. 307-319 ◽

Cited By ~ 13

Author(s):

Temuulen Sankey ◽

Jonathon Donald ◽

Jason McVay ◽

Mariah Ashley ◽

Frances O'Donnell ◽

...

Keyword(s):

North American ◽

Scale Analysis ◽

Multi Scale ◽

The North ◽

Southern Margin ◽

Snow Distribution ◽

Multi Scale Analysis

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Multi-scale analysis of wave conditions and coastal changes in the north-eastern Baltic Sea

Journal of Coastal Research ◽

10.2112/si70-038.1 ◽

2014 ◽

Vol 70 ◽

pp. 223-228 ◽

Cited By ~ 8

Author(s):

Ülo Suursaar ◽

Victor Alari ◽

Hannes Tõnisson

Keyword(s):

Baltic Sea ◽

Scale Analysis ◽

Multi Scale ◽

The North ◽

North Eastern ◽

Coastal Changes ◽

Wave Conditions ◽

Multi Scale Analysis ◽

Eastern Baltic

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Multi-scale analysis of the Monoceros OB 1 star-forming region

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936377 ◽

2019 ◽

Vol 631 ◽

pp. L1 ◽

Cited By ~ 2

Author(s):

Julien Montillaud ◽

Mika Juvela ◽

Charlotte Vastel ◽

Jinhua He ◽

Tie Liu ◽

...

Keyword(s):

Star Formation ◽

Joint Paper ◽

Infrared Observations ◽

Star Forming ◽

Multi Scale ◽

Dense Cores ◽

Cloud Dynamics ◽

Star Formation Activity ◽

A Chain ◽

The Relationship

Context. Current theories and models attempt to explain star formation globally, from core scales to giant molecular cloud scales. A multi-scale observational characterisation of an entire molecular complex is necessary to constrain them. We investigate star formation in G202.3+2.5, a ∼10 × 3 pc sub-region of the Monoceros OB1 cloud with a complex morphology that harbours interconnected filamentary structures. Aims. We aim to connect the evolution of cores and filaments in G202.3+2.5 with the global evolution of the cloud and to identify the engines of the cloud dynamics. Methods. In this first paper, the star formation activity is evaluated by surveying the distributions of dense cores and protostars and their evolutionary state, as characterised using both infrared observations from the Herschel and WISE telescopes and molecular line observations with the IRAM 30 m telescope. Results. We find ongoing star formation in the whole cloud, with a local peak in star formation activity around the centre of G202.3+2.5, where a chain of massive cores (10 − 50 M⊙) forms a massive ridge (≳150 M⊙). All evolutionary stages from starless cores to Class II protostars are found in G202.3+2.5, including a possibly starless and massive (52 M⊙) core, which presents a high column density (8 × 1022 cm−2). Conclusions. All the core-scale observables we examined point to an enhanced star formation activity that is centred on the junction between the three main branches of the ramified structure of G202.3+2.5. This suggests that the increased star formation activity results from the convergence of these branches. To further investigate the origin of this enhancement, it is now necessary to extend the analysis to larger scales in order to examine the relationship between cores, filaments, and their environment. We address these points through the analysis of the dynamics of G202.3+2.5 in a joint paper.

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Morphology and star formation in IllustrisTNG: the build-up of spheroids and discs

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1657 ◽

2019 ◽

Vol 487 (4) ◽

pp. 5416-5440 ◽

Cited By ~ 25

Author(s):

Sandro Tacchella ◽

Benedikt Diemer ◽

Lars Hernquist ◽

Shy Genel ◽

Federico Marinacci ◽

...

Keyword(s):

Star Formation ◽

Mass Density ◽

Stellar Mass ◽

High Mass ◽

Intermediate Mass ◽

Massive Galaxies ◽

Star Forming ◽

Star Formation Activity ◽

Stellar Motion ◽

Galaxy Morphology

ABSTRACT Using the IllustrisTNG simulations, we investigate the connection between galaxy morphology and star formation in central galaxies with stellar masses in the range 109–1011.5 M⊙. We quantify galaxy morphology by a kinematical decomposition of the stellar component into a spheroidal and a disc component (spheroid-to-total ratio, S/T) and by the concentration of the stellar mass density profile (C82). S/T is correlated with stellar mass and star formation activity, while C82 correlates only with stellar mass. Overall, we find good agreement with observational estimates for both S/T and C82. Low- and high-mass galaxies are dominated by random stellar motion, while only intermediate-mass galaxies (M⋆ ≈ 1010–1010.5 M⊙) are dominated by ordered rotation. Whereas higher mass galaxies are typical spheroids with high concentrations, lower mass galaxies have low concentration, pointing to different formation channels. Although we find a correlation between S/T and star formation activity, in the TNG model galaxies do not necessarily change their morphology when they transition through the green valley or when they cease their star formation, this depending on galaxy stellar mass and morphological estimator. Instead, the morphology (S/T and C82) is generally set during the star-forming phase of galaxies. The apparent correlation between S/T and star formation arises because earlier forming galaxies had, on average, a higher S/T at a given stellar mass. Furthermore, we show that mergers drive in situ bulge formation in intermediate-mass galaxies and are responsible for the recent spheroidal mass assembly in the massive galaxies with M⋆ > 1011 M⊙. In particular, these massive galaxies assemble about half of the spheroidal mass while star-forming and the other half through mergers while quiescent.

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