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Aims. Expanding HII regions and propagating shocks are common in the environment of young high-mass star-forming complexes. They can compress a pre-existing molecular cloud and trigger the formation of dense cores. We investigate whether…

The James Webb Space Telescope (JWST) is discovering an increasing number of galaxies well into the early stages of the Epoch of Reionization (EoR). Many of these galaxies are clustered with strong Lyman alpha (Ly$\alpha$) emission,…

Cometary ultracompact HII regions have been modelled as the interaction of the hypersonic wind from a moving star with the molecular cloud which surrounds the star. We here show that a similar morphology can ensue even if the star is…

Astrophysics · Physics 2015-06-24 R. J. R. Williams , J. E. Dyson , M. P. Redman

Mass loss from massive stars ($\ga 8 \msun$) can result in the formation of circumstellar wind blown cavities surrounding the star, bordered by a thin, dense, cold shell. When the star explodes as a core-collapse supernova (SN), the…

Astrophysics · Physics 2009-11-10 Vikram V. Dwarkadas

We report the discovery of eleven high-velocity HI clouds at Galactic latitudes of 25-30 degrees, likely embedded in the Milky Way's nuclear wind. The clouds are detected with deep Green Bank Telescope 21 cm observations of a $3.2^\circ…

Astrophysics of Galaxies · Physics 2025-07-08 Rongmon Bordoloi , Andrew J. Fox , Felix J. Lockman

We have conducted a survey of FUSE spectra of 235 Galactic B-type stars in order to determine the boundaries in the H-R diagram for the production of the superion O VI in their winds. By comparing the locations and morphology of otherwise…

Astrophysics · Physics 2009-11-07 J. Zsargo , A. W. Fullerton , N. Lehner , D. Massa

We study the Large Magellanic Cloud HII region N 214C using imaging and spectroscopy obtained at the ESO New Technology Telescope. On the basis of the highest resolution images so far obtained of the OB association LH 110, we show that the…

Astrophysics · Physics 2008-11-26 Frederic Meynadier , Mohammad Heydari-Malayeri , Nolan Walborn

Spectroscopic studies indicate that gas in the photospheres of young O stars moves at speeds up to the sound speed. We show, using two-dimensional radiation MHD calculations and results from a local linear analysis, that the motions may be…

Astrophysics · Physics 2007-05-23 N. J. Turner , H. W. Yorke , A. Socrates , O. M. Blaes

In this paper, we explore the significant, non-linear impact that stellar winds have on H ii regions. We perform a parameter study using three-dimensional radiative magnetohydrodynamic simulations of wind and ultraviolet radiation feedback…

Astrophysics of Galaxies · Physics 2024-02-02 Sam Geen , Rebekka Bieri , Alex de Koter , Taysun Kimm , Joakim Rosdahl

We identify a molecular bubble, and study the star formation and its feedback in the S Mon region, using multiple molecular lines, young stellar objects (YSOs), and infrared data. We revisit the distance to S Mon, ~722+/-9 pc, using Gaia…

Astrophysics of Galaxies · Physics 2024-02-01 Dejian Liu , Ye Xu , YingJie Li , Zehao Lin , Chaojie Hao , WenJin Yang , Jingjing Li , Xinrong Liu , Yiwei Dong , Shuaibo Bian , and Deyun Kong

Young massive stars or clusters are often observed at the peripheries of HII regions. What triggers star formation at such locations? Among the scenarios that have been proposed, the `collect and collapse' process is particularly attractive…

Astrophysics · Physics 2009-11-10 L. Deharveng , A. Zavagno , J. Caplan

High mass proto-stars create Ultra-Compact Hii regions (UCHII) at the stage of evolution when most of the accretion is finished but the star is still heavily embedded in molecular material. The morphologies of UCHII regions reflect the…

Astrophysics of Galaxies · Physics 2021-11-17 Dan Beilis , Sara Beck , John Lacy

We constructed diagnostic diagrams using emission line ratios and equivalent widths observed in several samples of HII galaxies. The diagrams are compared to predictions from new photoionization models for evolving starbursts. We find that…

Astrophysics · Physics 2009-11-06 Grazyna Stasinska , Daniel Schaerer , Claus Leitherer

AIMS: We investigate the environment of the infrared dust bubble N65 and search for evidence of triggered star formation in its surroundings. METHODS: We performed a multiwavelength study of the region around N65 with data taken from…

Astrophysics of Galaxies · Physics 2015-05-18 A. Petriella , S. A. Paron , E. B. Giacani

Several structures have been discovered embedded in regions of recent or ongoing star formation, which point to the importance of the interaction between fast moving wind-blowing stars and their environment. Using hydrodynamic simulations,…

Astrophysics · Physics 2009-10-30 Guillermo Tenorio-Tagle , Gustavo Medina Tanco

The properties of the Local Bubble, Local Fluff complex of nearby interstellar clouds, and the heliosphere are mutually constrained by data and theory. Observations and models of the diffuse radiation field, interstellar ionization, pick-up…

Astrophysics · Physics 2009-10-30 Priscilla C. Frisch

Observations of nearby molecular clouds detect "shells", which are likely caused by winds from young main sequence stars. However, the progenitors of these observed features are not well characterized and the mass-loss rates inferred from…

Astrophysics of Galaxies · Physics 2015-10-07 S. S. R. Offner , H. G. Arce

One of the fundamental factors regulating the evolution of galaxies is stellar feedback. However, we still do not have strong observational constraints on the relative importance of the different feedback mechanisms (e.g. radiation, ionised…

Massive stars are the key agents of feedback. Consequently, quantitative analysis of massive stars are required to understand how the feedback of these objects shapes/ creates the large scale structures of the ISM. The giant HII region N206…

Solar and Stellar Astrophysics · Physics 2017-12-27 Varsha Ramachandran , R. Hainich , W. -R. Hamann , L. M. Oskinova , T. Shenar , A. A. C. Sander , H. Todt , J. S. Gallagher

In recent works, through observations of molecular lines, we found that the supernova remnant (SNR) G18.8+0.3 is interacting with a molecular cloud towards its southern edge. Also it has been proven the presence of several neighboring HII…

Solar and Stellar Astrophysics · Physics 2016-06-02 M. Celis Peña , Sergio Paron