scholarly journals Surround and Squash: the impact of superbubbles on the interstellar medium in Scorpius–Centaurus OB2

2018 ◽  
Vol 619 ◽  
pp. A120 ◽  
Author(s):  
Martin G. H. Krause ◽  
Andreas Burkert ◽  
Roland Diehl ◽  
Katharina Fierlinger ◽  
Benjamin Gaczkowski ◽  
...  
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Massive Star ◽  
Massive Stars ◽  
Three Dimensional ◽  
X Rays ◽  
Hot Gas ◽  
Sky Survey ◽  
Hydrodynamical Simulations ◽  
The Impact

Context. Feedback by massive stars shapes the interstellar medium and is thought to influence subsequent star formation. The details of this process are under debate. Aims. We exploited observational constraints on stars, gas, and nucleosynthesis ashes for the closest region with recent massive-star formation, Scorpius–Centaurus OB2, and combined them with three-dimensional (3D) hydrodynamical simulations in order to address the physics and history of the Scorpius–Centaurus superbubble. Methods. We used published cold gas observations of continuum and molecular lines from Planck, Herschel, and APEX. We analysed the Galactic All Sky Survey (GASS) to investigate shell structures in atomic hydrogen, and used Hipparcos and Gaia data in combination with interstellar absorption against stars to obtain new constraints for the distance to the Hi features. Hot gas is traced in soft X-rays via the ROSAT all sky survey. Nucleosynthesis ejecta from massive stars were traced with new INTEGRAL spectrometer observations via 26Al radioactivity. We also performed 3D hydrodynamical simulations for the Sco–Cen superbubble. Results. Soft X-rays and a now more significant detection of 26Al confirm recent (≈1 Myr ago) input of mass, energy, and nucleosynthesis ejecta, likely from a supernova in the Upper Scorpius (USco) subgroup. We confirm a large supershell around the entire OB association and perform a 3D hydrodynamics simulation with a conservative massive star population that reproduces the morphology of the superbubble. High-resolution GASS observations reveal a nested, filamentary supershell. The filaments are possibly related to the Vishniac clumping instability, but molecular gas (Lupus I) is only present where the shell coincides with the connecting line between the subgroups of the OB association, suggesting a connection to the cloud, probably an elongated sheet, out of which the OB association formed. Stars have formed sequentially in the subgroups of the OB association and currently form in Lupus I. To investigate the impact of massive star feedback on extended clouds, we simulate the interaction of a turbulent cloud with the hot, pressurised gas in a superbubble. The hot gas fills the tenuous regions of the cloud and compresses the denser parts. Stars formed in these dense clumps would have distinct spatial and kinematic distributions. Conclusions. The combined results from observations and simulations are consistent with a scenario where dense gas was initially distributed in a band elongated in the direction now occupied by the OB association. Superbubbles powered by massive stars would then repeatedly break out of the elongated parent cloud, and surround and squash the denser parts of the gas sheet and thus induce more star formation. The expected spatial and kinematic distribution of stars is consistent with observations of Sco–Cen. The scenario might apply to many similar regions in the Galaxy and also to active galactic nucleus (AGN)-related superbubbles.

scholarly journals HII regions and star formation in the Magellanic Clouds

1991 ◽  
Vol 148 ◽  
pp. 139-144 ◽  
Author(s):  
Robert C. Kennicutt
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Massive Star ◽  
Massive Stars ◽  
Hii Regions ◽  
Magellanic Clouds ◽  
H Ii Regions ◽  
Distant Galaxies ◽  
Close Range ◽  
Mass Functions

The H II regions in the Magellanic Clouds provide an opportunity to characterize the global star formation properties of a galaxy at close range. They also provide a unique laboratory for testing empirical tracers of the massive star formation rates and initial mass functions in more distant galaxies, and for studying the dynamical interactions between massive stars and the interstellar medium. This paper discusses several current studies in these areas.

scholarly journals Stellar population of the superbubble N 206 in the LMC

2018 ◽  
Vol 615 ◽  
pp. A40 ◽  
Author(s):  
V. Ramachandran ◽  
W.-R. Hamann ◽  
R. Hainich ◽  
L. M. Oskinova ◽  
T. Shenar ◽  
...  
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Massive Stars ◽  
Mechanical Energy ◽  
Star Formation History ◽  
Photon Flux ◽  
Stellar Winds ◽  
Spectral Analyses ◽  
Ob Stars ◽  
Hot Gas

Context. Clusters or associations of early-type stars are often associated with a “superbubble” of hot gas. The formation of such superbubbles is caused by the feedback from massive stars. The complex N 206 in the Large Magellanic Cloud (LMC) exhibits a superbubble and a rich massive star population. Aims. Our goal is to perform quantitative spectral analyses of all massive stars associated with the N 206 superbubble in order to determine their stellar and wind parameters. We compare the superbubble energy budget to the stellar energy input and discuss the star formation history of the region. Methods. We observed the massive stars in the N 206 complex using the multi-object spectrograph FLAMES at ESO’s Very Large Telescope (VLT). Available ultra-violet (UV) spectra from archives are also used. The spectral analysis is performed with Potsdam Wolf–Rayet (PoWR) model atmospheres by reproducing the observations with the synthetic spectra. Results. We present the stellar and wind parameters of the OB stars and the two Wolf–Rayet (WR) binaries in the N 206 complex. Twelve percent of the sample show Oe/Be type emission lines, although most of them appear to rotate far below critical. We found eight runaway stars based on their radial velocity. The wind-momentum luminosity relation of our OB sample is consistent with the expectations. The Hertzsprung–Russell diagram (HRD) of the OB stars reveals a large age spread (1–30 Myr), suggesting different episodes of star formation in the complex. The youngest stars are concentrated in the inner part of the complex, while the older OB stars are scattered over outer regions. We derived the present day mass function for the entire N 206 complex as well as for the cluster NGC 2018. The total ionizing photon flux produced by all massive stars in the N 206 complex is Q0 ≈ 5 × 1050 s−1, and the mechanical luminosity of their stellar winds amounts to Lmec = 1.7 × 1038 erg s−1. Three very massive Of stars are found to dominate the feedback among 164 OB stars in the sample. The two WR winds alone release about as much mechanical luminosity as the whole OB star sample. The cumulative mechanical feedback from all massive stellar winds is comparable to the combined mechanical energy of the supernova explosions that likely occurred in the complex. Accounting also for the WR wind and supernovae, the mechanical input over the last five Myr is ≈ 2.3 × 1052 erg. Conclusions. The N206 complex in the LMC has undergone star formation episodes since more than 30 Myr ago. From the spectral analyses of its massive star population, we derive a current star formation rate of 2.2 × 10−3 M⊙ yr−1. From the combined input of mechanical energy from all stellar winds, only a minor fraction is emitted in the form of X-rays. The corresponding input accumulated over a long time also exceeds the current energy content of the complex by more than a factor of five. The morphology of the complex suggests a leakage of hot gas from the superbubble.

scholarly journals The Evolution of the Circumstellar and Interstellar Medium Around Massive Stars

2007 ◽  
Vol 3 (S250) ◽  
pp. 355-360
Author(s):  
S. Jane Arthur
Keyword(s):  
Stellar Wind ◽  
Massive Star ◽  
Main Sequence ◽  
Massive Stars ◽  
Central Star ◽  
Stellar Winds ◽  
X Rays ◽  
Hydrodynamic Calculations ◽  
The Impact ◽  
Size Scales

AbstractThroughout their lives massive stars modify their environment through their ionizing photons and strong stellar winds. Here, I present coupled radiation-hydrodynamic calculations of the evolution of the bubbles and nebulae surrounding massive stars. The evolution is followed from the main sequence through the Wolf-Rayet stage and shows that structures are formed in the ISM out to some tens of parsecs radius. Closer to the star, instabilities lead to the breakup of swept-up wind shells. The photoevaporated flows from the resulting clumps interact with the stellar wind from the central star, which leads to the production of soft X-rays. I examine the consequences for the different observable structures at all time and size scales and evaluate the impact that the massive star has on its environment.

Multiple Feedback in Low-Metallicity Massive Star Formation

2018 ◽  
Vol 14 (S344) ◽  
pp. 190-194
Author(s):  
Kei E. I. Tanaka ◽  
Jonathan C. Tan ◽  
Yichen Zhang ◽  
Takashi Hosokawa
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Massive Stars ◽  
Lower Surface ◽  
Mass Star ◽  
Massive Star Formation ◽  
Cluster Galaxy ◽  
Prestellar Cores ◽  
Low Metallicity ◽  
The Impact

AbstractWe theoretically investigate the impact of feedback and its metallicity dependence in massive star formation from prestellar cores at all metallicity range. We include the feedback by MHD disk winds, radiation pressure, and photoevaporation solving the evolution of protostars and accretion flows self-consistently. Interestingly, we find that the feedback does not set the upper mass limit of stellar birth mass at any metallicity. At the solar metallicity, the MHD disk wind is the dominant feedback to set the star formation efficiencies (SFEs) from the prestellar cores similar to low-mass star formation. The SFE is found to be lower at lower surface density environment. The photoevaporation becomes significant at the low metallicity of Z < 10−2 Z⊙. Considering this efficient photoevaporation, we conclude that the IMF slope is steeper, i.e., massive stars are rarer at the extremely metal-poor environment of 10−5 − 10−3Z⊙. Our study raises a question on the common assumption of the universal IMF with a truncated at 100M⊙. Since the total feedback strength in the cluster/galaxy scale is sensitive to the number fraction of massive stars, the re-evaluations of IMF at various environments are necessary.

scholarly journals Stellar wind and supernova feedback from massive stars

2012 ◽  
Vol 10 (H16) ◽  
pp. 586-586
Author(s):  
Julian M. Pittard ◽  
Hazel Rogers
Keyword(s):  
Stellar Wind ◽  
Massive Star ◽  
Massive Stars ◽  
Three Dimensional ◽  
Energy Fluxes ◽  
Hydrodynamical Models ◽  
Stellar Cluster ◽  
Molecular Material ◽  
The Impact ◽  
Supernova Feedback

AbstractWe have constructed three-dimensional hydrodynamical models to simulate the impact of massive star feedback, via winds and SNe, on inhomogeneous molecular material left over from the formation of a massive stellar cluster. We are studying the timescales for the molecular material to be removed from the environment of a massive stellar cluster and the mass and energy fluxes into the wider environment.

scholarly journals Turbulent structure and star formation in a stratified, supernova-driven, interstellar medium

2006 ◽  
Vol 2 (S237) ◽  
pp. 358-362
Author(s):  
M. K. Ryan Joung ◽  
Mordecai-Mark Mac Low
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Adaptive Mesh Refinement ◽  
Formation Rate ◽  
Three Dimensional ◽  
Adaptive Mesh ◽  
Mass Function ◽  
Initial Mass Function ◽  
Interstellar Turbulence ◽  
Self Gravity

AbstractWe report on a study of interstellar turbulence driven by both correlated and isolated supernova explosions. We use three-dimensional hydrodynamic models of a vertically stratified interstellar medium run with the adaptive mesh refinement code Flash at a maximum resolution of 2 pc, with a grid size of 0.5 × 0.5 × 10 kpc. Cold dense clouds form even in the absence of self-gravity due to the collective action of thermal instability and supersonic turbulence. Studying these clouds, we show that it can be misleading to predict physical properties such as the star formation rate or the stellar initial mass function using numerical simulations that do not include self-gravity of the gas. Even if all the gas in turbulently Jeans unstable regions in our simulation is assumed to collapse and form stars in local freefall times, the resulting total collapse rate is significantly lower than the value consistent with the input supernova rate. The amount of mass available for collapse depends on scale, suggesting a simple translation from the density PDF to the stellar IMF may be questionable. Even though the supernova-driven turbulence does produce compressed clouds, it also opposes global collapse. The net effect of supernova-driven turbulence is to inhibit star formation globally by decreasing the amount of mass unstable to gravitational collapse.

scholarly journals The Formation of Massive Stars

2010 ◽  
Vol 6 (S270) ◽  
pp. 57-64
Author(s):  
Ian A. Bonnell ◽  
Rowan J Smith
Keyword(s):  
Star Formation ◽  
Magnetic Fields ◽  
Massive Star ◽  
Massive Stars ◽  
Cluster Formation ◽  
High Mass ◽  
Prestellar Cores ◽  
Stellar Mergers ◽  
Massive Clusters ◽  
Viable Mechanism

AbstractThere has been considerable progress in our understanding of how massive stars form but still much confusion as to why they form. Recent work from several sources has shown that the formation of massive stars through disc accretion, possibly aided by gravitational and Rayleigh-Taylor instabilities is a viable mechanism. Stellar mergers, on the other hand, are unlikely to occur in any but the most massive clusters and hence should not be a primary avenue for massive star formation. In contrast to this success, we are still uncertain as to how the mass that forms a massive star is accumulated. there are two possible mechanisms including the collapse of massive prestellar cores and competitive accretion in clusters. At present, there are theoretical and observational question marks as to the existence of high-mass prestellar cores. theoretically, such objects should fragment before they can attain a relaxed, centrally condensed and high-mass state necessary to form massive stars. Numerical simulations including cluster formation, feedback and magnetic fields have not found such objects but instead point to the continued accretion in a cluster potential as the primary mechanism to form high-mass stars. Feedback and magnetic fields act to slow the star formation process and will reduce the efficiencies from a purely dynamical collapse but otherwise appear to not significantly alter the process.

scholarly journals Radiative Feedback Effects during Cosmic Reionization

2014 ◽  
Vol 11 (S308) ◽  
pp. 372-377
Author(s):  
David Sullivan ◽  
Ilian T. Iliev
Keyword(s):  
Star Formation ◽  
Radiation Field ◽  
Early Universe ◽  
Galaxy Formation ◽  
Analytical Models ◽  
Feedback Effects ◽  
Radiative Feedback ◽  
Hydrodynamical Simulations ◽  
Matching Models ◽  
The Impact

AbstractWe present coupled radiation hydrodynamical simulations of the epoch of reionization, aimed at probing self-feedback on galactic scales. Unlike previous works, which assume a (quasi) homogeneous UV background, we self-consistently evolve both the radiation field and the gas to model the impact of previously unresolved processes such as spectral hardening and self-shielding. We find that the characteristic halo mass with a gas fraction half the cosmic mean, Mc(z), a quantity frequently used in semi-analytical models of galaxy formation, is significantly larger than previously assumed. While this results in an increased suppression of star formation in the early Universe, our results are consistent with the extrapolated stellar abundance matching models from Moster et al. 2013.

Sign in / Sign up

Export Citation Format

Share Document