scholarly journals On the early evolution of massive star clusters: the case of cloud D1 and its embedded cluster in NGC 5253

2020 ◽  
Vol 494 (1) ◽  
pp. 97-107 ◽  
Author(s):  
Sergiy Silich ◽  
Guillermo Tenorio-Tagle ◽  
Sergio Martínez-González ◽  
Jean Turner
Keyword(s):  
Massive Star ◽  
Massive Stars ◽  
Star Clusters ◽  
Early Evolution ◽  
Mass Loading ◽  
Low Mass Stars ◽  
Stellar Cluster ◽  
Star Forming ◽  
Cluster Phase ◽  
Protostellar Discs

ABSTRACT We discuss a theoretical model for the early evolution of massive star clusters and confront it with the ALMA, radio, and infrared observations of the young stellar cluster highly obscured by the molecular cloud D1 in the nearby dwarf spheroidal galaxy NGC 5253. We show that a large turbulent pressure in the central zones of D1 cluster may cause individual wind-blown bubbles to reach pressure confinement before encountering their neighbours. In this case, stellar winds energy is added to the hot shocked wind pockets of gas around individual massive stars that leads them to meet and produce a cluster wind in time-scales less than 105 yr. In order to inhibit the possibility of cloud dispersal, or the early negative star formation feedback, one should account for mass loading that may come, for example, from pre-main-sequence (PMS) low-mass stars through photoevaporation of their protostellar discs. Mass loading at a rate in excess of 8 × 10−9 M⊙ yr−1 per each PMS star is required to extend the hidden star cluster phase in this particular cluster. In this regime, the parental cloud remains relatively unperturbed, while pockets of molecular, photoionized and hot gas coexist within the star-forming region. Nevertheless, the most likely scenario for cloud D1 and its embedded cluster is that the hot shocked winds around individual massive stars should merge at an age of a few million of years when the PMS star protostellar discs vanish and mass loading ceases that allows a cluster to form a global wind.

scholarly journals The Circumstellar Environment of Embedded Massive Stars

2002 ◽  
Vol 12 ◽  
pp. 143-145 ◽  
Author(s):  
Lee G. Mundy ◽  
Friedrich Wyrowski ◽  
Sarah Watt
Keyword(s):  
Massive Star ◽  
Massive Stars ◽  
Low Mass Stars ◽  
Submillimeter Wavelength ◽  
Star Forming ◽  
Star Forming Regions ◽  
Low Mass ◽  
Circumstellar Environments ◽  
Near Future

Millimeter and submillimeter wavelength images of massive star-forming regions are uncovering the natal material distribution and revealing the complexities of their circumstellar environments on size scales from parsecs to 100’s of AU. Progress in these areas has been slower than for low-mass stars because massive stars are more distant, and because they are gregarious siblings with different evolutionary stages that can co-exist even within a core. Nevertheless, observational goals for the near future include the characterization of an early evolutionary sequence for massive stars, determination if the accretion process and formation sequence for massive stars is similar to that of low-mass stars, and understanding of the role of triggering events in massive star formation.

scholarly journals ALMA and ROSINA detections of phosphorus-bearing molecules: the interstellar thread between star-forming regions and comets

2020 ◽  
Vol 492 (1) ◽  
pp. 1180-1198 ◽  
Author(s):  
V M Rivilla ◽  
M N Drozdovskaya ◽  
K Altwegg ◽  
P Caselli ◽  
M T Beltrán ◽  
...  
Keyword(s):  
Gas Phase ◽  
Massive Star ◽  
Massive Stars ◽  
Early Earth ◽  
Low Velocity ◽  
Stellar Cluster ◽  
Star Forming ◽  
Star Forming Regions ◽  
Uv Photons ◽  
Comet 67P

ABSTRACT To understand how phosphorus (P)-bearing molecules are formed in star-forming regions, we have analysed the Atacama Large Millimeter/Submillimeter Array (ALMA) observations of PN and PO towards the massive star-forming region AFGL 5142, combined with a new analysis of the data of the comet 67P/Churyumov–Gerasimenko taken with the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument onboard Rosetta. The ALMA maps show that the emission of PN and PO arises from several spots associated with low-velocity gas with narrow linewidths in the cavity walls of a bipolar outflow. PO is more abundant than PN in most of the spots, with the PO/PN ratio increasing as a function of the distance to the protostar. Our data favour a formation scenario in which shocks sputter phosphorus from the surface of dust grains, and gas-phase photochemistry induced by UV photons from the protostar allows efficient formation of the two species in the cavity walls. Our analysis of the ROSINA data has revealed that PO is the main carrier of P in the comet, with PO/PN > 10. Since comets may have delivered a significant amount of prebiotic material to the early Earth, this finding suggests that PO could contribute significantly to the phosphorus reservoir during the dawn of our planet. There is evidence that PO was already in the cometary ices prior to the birth of the Sun, so the chemical budget of the comet might be inherited from the natal environment of the Solar system, which is thought to be a stellar cluster including also massive stars.

scholarly journals From young massive star clusters to old globulars: long-term survival chances

2006 ◽  
Vol 2 (S237) ◽  
pp. 408-408
Author(s):  
Richard de Grijs
Keyword(s):  
Galaxy Formation ◽  
Massive Star ◽  
Cluster Formation ◽  
Star Clusters ◽  
Term Survival ◽  
Star Forming ◽  
Distant Galaxies ◽  
Wide Range ◽  
Galaxy Collisions

Young, massive star clusters (YMCs) are the most notable and significant end products of violent star-forming episodes triggered by galaxy collisions and close encounters. The question remains, however, whether or not at least a fraction of the compact YMCs seen in abundance in extragalactic starbursts, are potentially the progenitors of (≳10 Gyr) old globular cluster (GC)-type objects. If we could settle this issue convincingly, one way or the other, the implications of such a result would have far-reaching implications for a wide range of astrophysical questions, including our understanding of the process of galaxy formation and assembly, and the process and conditions required for star (cluster) formation. Because of the lack of a statistically significant sample of YMCs in the Local Group, however, we need to resort to either statistical arguments or to the painstaking approach of case-by-case studies of individual objects in more distant galaxies.

scholarly journals Star cluster formation and cloud dispersal by radiative feedback: dependence on metallicity and compactness

2020 ◽  
Vol 497 (3) ◽  
pp. 3830-3845 ◽  
Author(s):  
Hajime Fukushima ◽  
Hidenobu Yajima ◽  
Kazuyuki Sugimura ◽  
Takashi Hosokawa ◽  
Kazuyuki Omukai ◽  
...  
Keyword(s):  
Star Formation ◽  
Massive Stars ◽  
Cluster Formation ◽  
Star Clusters ◽  
Star Cluster ◽  
Star Forming ◽  
Dynamical Time ◽  
Low Metallicity ◽  
Higher Temperature ◽  
Dust Attenuation

ABSTRACT We study star cluster formation in various environments with different metallicities and column densities by performing a suite of 3D radiation hydrodynamics simulations. We find that the photoionization feedback from massive stars controls the star formation efficiency (SFE) in a star-forming cloud, and its impact sensitively depends on the gas metallicity Z and initial cloud surface density Σ. At Z = 1 Z⊙, SFE increases as a power law from 0.03 at Σ = 10 M⊙ pc−2 to 0.3 at $\Sigma = 300\,\mathrm{M}_{\odot }\, {\rm pc^{-2}}$. In low-metallicity cases $10^{-2}\!-\!10^{-1}\, \mathrm{Z}_{\odot }$, star clusters form from atomic warm gases because the molecule formation time is not short enough with respect to the cooling or dynamical time. In addition, the whole cloud is disrupted more easily by expanding H ii bubbles that have higher temperature owing to less efficient cooling. With smaller dust attenuation, the ionizing radiation feedback from nearby massive stars is stronger and terminate star formation in dense clumps. These effects result in inefficient star formation in low-metallicity environments: the SFE drops by a factor of ∼3 at Z = 10−2 Z⊙ compared to the results for Z = 1 Z⊙, regardless of Σ. Newborn star clusters are also gravitationally less bound. We further develop a new semi-analytical model that can reproduce the simulation results well, particularly the observed dependencies of the SFEs on the cloud surface densities and metallicities.

scholarly journals The influence of feedback from massive stars on the formation and emergence of massive clusters

2015 ◽  
Vol 12 (S316) ◽  
pp. 177-183
Author(s):  
James E. Dale
Keyword(s):  
Large Scale ◽  
Massive Star ◽  
Massive Stars ◽  
Cluster Structure ◽  
Star Clusters ◽  
Stellar Feedback ◽  
Making Sense ◽  
Formation Efficiency ◽  
Massive Clusters ◽  
Made In

AbstractMassive star clusters are of fundamental importance both observationally, since they are visible at such great distances, and theoretically, because of their influence on the large–scale ISM. Understanding stellar feedback is a prerequisite for making sense of their formation and early evolution, since feedback influences cluster structure, star formation efficiency, and sets the timescales on which clusters emerge from their parent clouds to become optically visible. I review the progress made in understanding these issues from a numerical perspective.

scholarly journals OB stars towards NGC 6357 and NGC 6334

2017 ◽  
Vol 12 (S330) ◽  
pp. 341-342
Author(s):  
Delphine Russeil
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Stellar Population ◽  
Proper Motions ◽  
Massive Star Formation ◽  
Ob Stars ◽  
Stellar Cluster ◽  
Star Forming ◽  
Star Forming Regions ◽  
Ngc 6334

AbstractThe star forming regions NGC6334 and NGC6357 are amid the most active star-forming complexes of our Galaxy where massive star formation is occuring. Both complexes gather several HII regions but they exhibit different aspects: NGC6334 is characterised by a dense molecular ridge where recent massive star formation is obvious while NGC6357 is dominated by the action of the stellar cluster Pismis 24 which have shaped a large cavity. To understand and compare the formation of massive stars in these two regions requires to precise the distance and characterise the proper motions of the O to B3 stellar population in these regions.

scholarly journals The [O iii]+H β equivalent width distribution at z ≃ 7: implications for the contribution of galaxies to reionization

2020 ◽  
Vol 500 (4) ◽  
pp. 5229-5248
Author(s):  
Ryan Endsley ◽  
Daniel P Stark ◽  
Jacopo Chevallard ◽  
Stéphane Charlot
Keyword(s):  
Star Formation ◽  
Standard Deviation ◽  
Equivalent Width ◽  
Production Efficiency ◽  
Massive Star ◽  
Star Clusters ◽  
Strong Variation ◽  
Star Forming ◽  
Width Distribution ◽  
Intense Star Formation

ABSTRACT We quantify the distribution of [O iii]+H β line strengths at z ≃ 7 using a sample of 20 bright ($\mathrm{M}_{\mathrm{UV}}^{}$ ≲ –21) galaxies. We select these systems over wide-area fields (2.3 deg2 total) using a new colour-selection that precisely selects galaxies at z ≃ 6.63–6.83, a redshift range where blue Spitzer/IRAC [3.6]−[4.5] colours unambiguously indicate strong [O iii]+H β emission. These 20 galaxies suggest a lognormal [O iii]+H β EW distribution with median EW = 759$^{+112}_{-113}$ Å and standard deviation = 0.26$^{+0.06}_{-0.05}$ dex. We find no evidence for strong variation in this EW distribution with UV luminosity. The typical [O iii]+H β EW at z ≃ 7 implied by our sample is considerably larger than that in massive star-forming galaxies at z ≃ 2, consistent with a shift towards larger average sSFR (4.4 Gyr−1) and lower metallicities (0.16 Z⊙). We also find evidence for the emergence of a population with yet more extreme nebular emission ([O iii]+H β EW > 1200 Å) that is rarely seen at lower redshifts. These objects have extremely large sSFR (>30 Gyr−1), as would be expected for systems undergoing a burst or upturn in star formation. While this may be a short-lived phase, our results suggest that 20 per cent of the z ≃ 7 population has such extreme nebular emission, implying that galaxies likely undergo intense star formation episodes regularly at z > 6. We argue that this population may be among the most effective ionizing agents in the reionization era, both in terms of photon production efficiency and escape fraction. We furthermore suggest that galaxies passing through this large sSFR phase are likely to be very efficient in forming bound star clusters.

scholarly journals Massive Star Formation in the Ultraviolet Observed with the Hubble Space Telescope

Galaxies ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 13 ◽  
Author(s):  
Claus Leitherer
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Hubble Space Telescope ◽  
Spectral Synthesis ◽  
Star Clusters ◽  
Large Magellanic Cloud ◽  
H Ii Regions ◽  
Massive Star Formation ◽  
Space Telescope ◽  
Star Forming

Spectroscopic observations of a massive star formation in the ultraviolet and their interpretation are reviewed. After a brief historical retrospective, two well-studied resolved star clusters and the surrounding H II regions are introduced: NGC 2070 in the Large Magellanic Cloud and NGC 604 in M33. These regions serve as a training set for studies of more distant clusters, which can no longer be resolved into individual stars. Observations of recently formed star clusters and extended regions in star-forming galaxies in the nearby universe beyond the Local Group are presented. Their interpretation relies on spectral synthesis models. The successes and failures of such models are discussed, and future directions are highlighted. I present a case study of the extraordinary star cluster and giant H II region in the blue compact galaxy II Zw 40. The review concludes with a preview of two upcoming Hubble Space Telescope programs: ULLYSES, a survey of massive stars in nearby galaxies, and CLASSY, a study of massive star clusters in star-forming galaxies.

scholarly journals Recombination line masers in YSOs

2002 ◽  
Vol 206 ◽  
pp. 226-233 ◽  
Author(s):  
Jesús Martín-Pintado
Keyword(s):  
Massive Star ◽  
Laser Emission ◽  
Massive Stars ◽  
Recombination Line ◽  
Maser Emission ◽  
Star Forming ◽  
Star Forming Regions ◽  
Millimeter Wavelengths ◽  
The Impact ◽  
Early Phases

Maser emission from recombination lines has been detected towards the Young Stellar Object (YSO) MWC349 and the massive evolved star η Carinae. In spite of extensive searches of recombination line maser emission at millimeter wavelengths towards massive star forming regions, MWC349 remains unique. MWC349 is also a strong recombination line laser in the Far-IR with the largest amplification observed for transitions at wavelengths around 400 μm. The observational properties of the recombination line maser and laser emission from MWC349 are reviewed. Modeling of the maser and laser emission in MWC349 will be used to illustrate the potential of this kind of masers to understand the early phases of the evolution of massive stars. The impact that future instruments like the Herschel, the SMA and specially ALMA, will have in the investigation of recombination line maser emission from YSOs is briefly discussed.

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