scholarly journals Massive Stars: Their Contribution to Energy and Element Budget in Chemo-Dynamical Galaxy Evolution

2007 ◽  
Vol 24 ◽  
pp. 113-118 ◽  
Author(s):  
G. Hensler
Keyword(s):  
Galaxy Evolution ◽  
Massive Stars ◽  
Element Budget

scholarly journals Simulated X-Ray Emission from Starburst Driven Winds

1998 ◽  
Vol 188 ◽  
pp. 287-288
Author(s):  
D. K. Strickland ◽  
I. R. Stevens ◽  
T. J. Ponman
Keyword(s):  
Galaxy Evolution ◽  
Massive Stars ◽  
Temperature Structure ◽  
Mass Loading ◽  
X Ray ◽  
Chemical Enrichment ◽  
Hot Gas ◽  
Galactic Winds ◽  
Complex Temperature ◽  
Initial Results

Winds from massive stars and supernovae in starburst galaxies drive global outflows of hot X-ray emitting plasma, as seen in M82 and NGC 253. These galactic winds are important for understanding galaxy evolution & formation, chemical enrichment of the IGM, and the starburst phenomenon itself.X-ray observations provide the only direct probe of the hot gas in these winds. However, the limitations of current X-ray observatories and factors such as complex temperature structure, mass loading by ambient material and projection effects all make the link between the observed data and existing 1 & 2-D modeling and theory difficult to make.We have therefore begun a program of numerical simulations of galactic winds, concentrating on predicting their observable X-ray properties. We present some initial results, comparing them to the archetypal starburst wind system M82.

Star formation at low rates: impact of lacking massive stars on the evolution of dwarf galaxies

2018 ◽  
Vol 14 (S344) ◽  
pp. 186-189
Author(s):  
P. Steyrleithner ◽  
G. Hensler ◽  
S. Recchi ◽  
S. Ploeckinger
Keyword(s):  
Star Formation ◽  
Numerical Simulations ◽  
Galaxy Evolution ◽  
Dwarf Galaxies ◽  
Massive Stars ◽  
Self Regulation ◽  
Mass Function ◽  
Initial Mass Function ◽  
Single Star ◽  
The Imf

AbstractIn recent years dedicated observations have uncovered star formation at extremely low rates in dwarf galaxies, tidal tails, ram-pressure stripped gas clouds, and the outskirts of galactic disks. At the same time, numerical simulations of galaxy evolution have advanced to higher spatial and mass resolutions, but have yet to account for the underfilling of the uppermost mass bins of stellar initial mass function (IMF) at low star-formation rates. In such situations, simulations may simply scale down the IMF, without realizing that this unrealistically results in fractions of massive stars, along with fractions of massive star feedback energy (e.g., radiation and SNII explosions). Not properly accounting for such parameters has consequences for the self-regulation of star formation, the energetics of galaxies, as well as for the evolution of chemical abundances. Here we present numerical simulations of dwarf galaxies with low star-formation rates allowing for two extreme cases of the IMF: a “filled” case with fractional massive stars vs. a truncated IMF, at which the IMF is built bottom-up until the gas reservoir allows the formation of a last single star at an uppermost mass. The aim of the study is to demonstrate the different effects on galaxy evolution with respect to self-regulation, feedback, and chemistry. The case of a stochastic sampled IMF is situated somewhere in between these extremes.

scholarly journals Role of massive stars in the evolution of primitive galaxies

2012 ◽  
Vol 10 (H16) ◽  
pp. 370-370
Author(s):  
Sara Heap
Keyword(s):  
Galaxy Evolution ◽  
Dwarf Galaxy ◽  
Massive Stars ◽  
Stellar Winds ◽  
Stellar Feedback ◽  
Low Metallicity ◽  
Low Mass ◽  
Blue Compact Dwarf Galaxy

AbstractAn important factor controlling galaxy evolution is feedback from massive stars. It is believed that the nature and intensity of stellar feedback changes as a function of galaxy mass and metallicity. At low mass and metallicity, feedback from massive stars is mainly in the form of photoionizing radiation. At higher mass and metallicity, it is in stellar winds. I Zw 18 is a local blue, compact dwarf galaxy that meets the requirements for a primitive galaxy: low halo mass <109M⊙, strong photoionizing radiation, no galactic outflow, and very low metallicity, log(O/H)+12=7.2. We will describe the properties of massive stars and their role in the evolution of I Zw 18, based on analysis of ultraviolet images and spectra obtained with HST.

Poster abstracts

2007 ◽  
Vol 3 (S250) ◽  
pp. 525-568
Keyword(s):  
Galaxy Evolution ◽  
Early Universe ◽  
Massive Star ◽  
Massive Stars

SESSION I: Atmospheres of Massive StarsSESSION II: Physics and Evolution of Massive StarsSESSION III: Massive Star Populations in the Nearby UniverseSESSION IV: Hydrodynamics and Feedback from Massive Stars in Galaxy EvolutionSESSION V: Massive Stars as Probes of the Early Universe

scholarly journals A Missing Link in Galaxy Evolution: The Mysteries of Dissolving Star Clusters

2006 ◽  
Vol 2 (S235) ◽  
pp. 128-128
Author(s):  
Anne Pellerin ◽  
Martin Meyer ◽  
Jason Harris ◽  
Daniela Calzetti
Keyword(s):  
Galaxy Evolution ◽  
Massive Stars ◽  
Star Clusters ◽  
Starburst Galaxies ◽  
Stellar Clusters ◽  
Diffuse Emission ◽  
Missing Link ◽  
Normal Galaxies ◽  
Uv Emission

Assuming that most stars form in clusters (Lada & Lada 2003), one might initially expect to find most massive stars in stellar clusters and to detect most of the UV emission in young compact stellar clusters. However, Meurer et al. (1995) showed that in starburst galaxies only 20% of the UV emission at 2200Å is detected in clusters while 80% is diffuse emission from sources in the inter-cluster medium. This phenomenon is also observed for normal galaxies (Hoopes et al. 2001).

scholarly journals The earliest phases of galaxy evolution: massive stars

1999 ◽  
Vol 193 ◽  
pp. 734-735
Author(s):  
Cristina Chiappini ◽  
Francesca Matteucci ◽  
Timothy C. Beers ◽  
Ken'Ichi Nomoto
Keyword(s):  
Galaxy Evolution ◽  
Chemical Evolution ◽  
Massive Stars ◽  
Solar Neighborhood ◽  
Evolution Model ◽  
Elemental Abundances ◽  
Extended Range ◽  
Solar Abundances ◽  
Early Phases ◽  
Chemical Evolution Model

In this work we study the very early phases of the evolution of our Galaxy by means of a chemical evolution model which reproduces most of the observational constraints in the solar vicinity and in the disk. We have restricted our analysis to the solar neighborhood and present the predicted abundances of several elements (C, N, 0, Mg, Si, S, Ca, Fe) over an extended range of metallicities [Fe/H] = −4.0 to 0.0 compared to previous models. We adopted the most recent yield calculations for massive stars taken from different authors (Woosley & Weaver 1995; Thielemann et al. 1996) and compared the results with a very large sample of data, one of the largest ever used to this purpose. We have obtained this by selecting the most rec.ent and higher quality abundance data from a number of sources and renormalizing them to the same solar abundances. These data have been analysed with a new and powerful statistical method which allows us to quantify the observational spread in measured elemental abundances and obtain a more meaningful comparison with the predictions from our chemical evolution model.

scholarly journals Forming an “Impossible” 85 solar mass Black Hole

2020 ◽  
Author(s):  
Jorick Vink ◽  
Erin Higgins ◽  
Andreas Sander ◽  
Gautham Sabhahit
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Galaxy Evolution ◽  
Heavy Element ◽  
Massive Stars ◽  
Fundamental Problem ◽  
Cosmic Time ◽  
Host Galaxy ◽  
Solar Mass ◽  
The Masses

Abstract At the end of its life, a very massive star is expected to collapse into a black hole. The masses of these black holes are pivotal for our understanding of the evolution and fate of these stars, as well as for galaxy evolution and the build-up of black hole masses through Cosmic time. The recent detection of an 85 solar mass black hole from the gravitational wave event GW 190521 appears to present a fundamental problem as to how such heavy black holes exist above the approximately 50 solar mass pair-instability limit where stars are expected to be blown to pieces with no remnant left. Here we show that for stellar models at reduced heavy element content, 90-100 solar mass stars can produce core masses sufficiently small to remain below the fundamental pair-instability limit, yet at the same time lose an amount of mass small enough to end up in an 85 solar mass black hole. A key point is that the amount of mass-loss scales with the host galaxy heavy element fraction, and not with the total amount of element enrichment that occurs naturally during the life of massive stars. Our study shows how our Universe is capable of producing heavy black holes, which are important seeds for the production of supermassive black holes that regulate the evolution of galaxies. Our evolutionary channel to the formation of an 85 solar mass black hole is of fundamental relevance for the manner in which metals are released in the outflows and explosions of the most massive stars, which is shown to be a strong function of Cosmic time.

Central kiloparsec of NGC 1326 observed with SINFONI

2020 ◽  
Vol 638 ◽  
pp. A53
Author(s):  
Nastaran Fazeli ◽  
Gerold Busch ◽  
Andreas Eckart ◽  
Françoise Combes ◽  
Persis Misquitta ◽  
...  
Keyword(s):  
Black Hole ◽  
Galaxy Evolution ◽  
Near Infrared ◽  
Velocity Fields ◽  
Molecular Gas ◽  
Nearby Galaxy ◽  
Stellar Content ◽  
Stellar Rotation ◽  
Supermassive Black Hole ◽  
Integral Field Spectrograph

Gas inflow processes in the vicinity of galactic nuclei play a crucial role in galaxy evolution and supermassive black hole growth. Exploring the central kiloparsec of galaxies is essential to shed more light on this subject. We present near-infrared H- and K-band results of the nuclear region of the nearby galaxy NGC 1326, observed with the integral-field spectrograph SINFONI mounted on the Very Large Telescope. The field of view covers 9″ × 9″ (650 × 650 pc2). Our work is concentrated on excitation conditions, morphology, and stellar content. The nucleus of NGC 1326 was classified as a LINER, however in our data we observed an absence of ionised gas emission in the central r ∼ 3″. We studied the morphology by analysing the distribution of ionised and molecular gas, and thereby detected an elliptically shaped, circum-nuclear star-forming ring at a mean radius of 300 pc. We estimate the starburst regions in the ring to be young with dominating ages of < 10 Myr. The molecular gas distribution also reveals an elongated east to west central structure about 3″ in radius, where gas is excited by slow or mild shock mechanisms. We calculate the ionised gas mass of 8 × 105 M⊙ completely concentrated in the nuclear ring and the warm molecular gas mass of 187 M⊙, from which half is concentrated in the ring and the other half in the elongated central structure. The stellar velocity fields show pure rotation in the plane of the galaxy. The gas velocity fields show similar rotation in the ring, but in the central elongated H2 structure they show much higher amplitudes and indications of further deviation from the stellar rotation in the central 1″ aperture. We suggest that the central 6″ elongated H2 structure might be a fast-rotating central disc. The CO(3–2) emission observations with the Atacama Large Millimeter/submillimeter Array reveal a central 1″ torus. In the central 1″ of the H2 velocity field and residual maps, we find indications for a further decoupled structure closer to a nuclear disc, which could be identified with the torus surrounding the supermassive black hole.

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