scholarly journals Expanding bubbles in Orion A: [C II] observations of M 42, M 43, and NGC 1977

2020 ◽  
Vol 639 ◽  
pp. A2 ◽  
Author(s):  
C. H. M. Pabst ◽  
J. R. Goicoechea ◽  
D. Teyssier ◽  
O. Berné ◽  
R. D. Higgins ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Massive Stars ◽  
Mechanical Energy ◽  
Cosmological Parameters ◽  
Analytical Models ◽  
High Spectral Resolution ◽  
Expansion Velocity ◽  
Stellar Winds ◽  
Orion Nebula ◽  
Expansion Time

Context. The Orion Molecular Cloud is the nearest massive-star forming region. Massive stars have profound effects on their environment due to their strong radiation fields and stellar winds. Stellar feedback is one of the most crucial cosmological parameters that determine the properties and evolution of the interstellar medium in galaxies. Aims. We aim to understand the role that feedback by stellar winds and radiation play in the evolution of the interstellar medium. Velocity-resolved observations of the [C II] 158 μm fine-structure line allow us to study the kinematics of UV-illuminated gas. Here, we present a square-degree-sized map of [C II] emission from the Orion Nebula complex at a spatial resolution of 16′′ and high spectral resolution of 0.2 km s−1, covering the entire Orion Nebula (M 42) plus M 43 and the nebulae NGC 1973, 1975, and 1977 to the north. We compare the stellar characteristics of these three regions with the kinematics of the expanding bubbles surrounding them. Methods. We use [C II] 158 μm line observations over an area of 1.2 deg2 in the Orion Nebula complex obtained by the upGREAT instrument onboard SOFIA. Results. The bubble blown by the O7V star θ1 Ori C in the Orion Nebula expands rapidly, at 13 km s−1. Simple analytical models reproduce the characteristics of the hot interior gas and the neutral shell of this wind-blown bubble and give us an estimate of the expansion time of 0.2 Myr. M 43 with the B0.5V star NU Ori also exhibits an expanding bubble structure, with an expansion velocity of 6 km s−1. Comparison with analytical models for the pressure-driven expansion of H II regions gives an age estimate of 0.02 Myr. The bubble surrounding NGC 1973, 1975, and 1977 with the central B1V star 42 Orionis expands at 1.5 km s−1, likely due to the over-pressurized ionized gas as in the case of M 43. We derive an age of 0.4 Myr for this structure. Conclusions. We conclude that the bubble of the Orion Nebula is driven by the mechanical energy input by the strong stellar wind from θ1 Ori C, while the bubbles associated with M 43 and NGC 1977 are caused by the thermal expansion of the gas ionized by their central later-type massive stars.

scholarly journals The interstellar medium local to HD 10125 (O9.7II)

2003 ◽  
Vol 212 ◽  
pp. 700-701
Author(s):  
Silvina Cichowolski ◽  
E. Marcelo Arnal ◽  
Cristina E. Cappa ◽  
Sergey Pineault ◽  
Nicole St-Louis
Keyword(s):  
High Temperature ◽  
Interstellar Medium ◽  
Massive Stars ◽  
Mechanical Energy ◽  
Volume Density ◽  
Stellar Winds ◽  
Gas Distribution ◽  
Huge Number ◽  
Structure And Dynamics ◽  
Low Volume

The structure and dynamics of the interstellar medium (ISM) are strongly affected by the action of massive stars. They deposit in the ISM a huge number of ionizing photons and transfer to it vast amounts of mechanical energy via their powerful stellar winds. As a consequence, massive stars create what is known as an interstellar bubble, i.e., a minimum in the gas distribution characterized by a low volume density and a high temperature, surrounded by an expanding envelope (Weaver et al. 1977). The star should be seen projected onto, or close to, the centre of the H i minimum.

scholarly journals Massive stars shaping the ISM: H I holes and shells in nearby galaxies

1999 ◽  
Vol 193 ◽  
pp. 636-644
Author(s):  
Elias Brinks ◽  
Fabian Walter
Keyword(s):  
Interstellar Medium ◽  
Dwarf Galaxy ◽  
Massive Stars ◽  
Neutral Hydrogen ◽  
Neutral Medium ◽  
Stellar Winds ◽  
X Ray ◽  
Left Behind ◽  
Neutral Gas ◽  
Nearby Galaxies

Neutral hydrogen (H I) is a magnificent tool when studying the structure of the interstellar medium (ISM) as it is relatively easily observable and can be mapped at good spatial and velocity resolution with modern instruments. Moreover, it traces the cool (∼ 100 K) and warm (∼ 5000 K) neutral gas which together make up about 60%, or the bulk, of the ISM. The currently accepted picture is that stellar winds and subsequent supernovae are the origin for the clearly defined holes or bubbles within the more or less smooth neutral medium. The H I can therefore serve indirectly as a tracer of the hot interstellar medium (HIM) left behind after the most massive stars within an OB association have gone off as supernovae. A splendid example is the dwarf galaxy IC 2574 for which we discuss H I, optical and X-ray observations.

scholarly journals X-ray Emission from Massive Stars at the Core of Very Young Clusters

2016 ◽  
Vol 12 (S329) ◽  
pp. 362-365
Author(s):  
Norbert S. Schulz
Keyword(s):  
Massive Stars ◽  
Stellar Winds ◽  
X Rays ◽  
Stellar Clusters ◽  
Orion Nebula ◽  
X Ray ◽  
The Core ◽  
Hot Plasma ◽  
Young Clusters ◽  
Massive Cluster

AbstractMost cores of very young stellar clusters contain one or more massive stars at various evolutionary stages. Observations of the Orion Nebula Cluster, Trumpler 37, NGC 2362, RCW38, NGC 3603 and many others provide the most comprehensive database to study stellar wind properties of these massive cluster stars in X-rays. In this presentation we review some of these observations and results and discuss them in the context of stellar winds and possible evolutionary implications. We argue that in very young clusters such as RCW38 and M17, shock heated remnants of a natal shell could serve as an alternate explanation to the colliding wind paradigm for the hot plasma components in the X-ray spectra.

scholarly journals Magnetic fields, winds and X-rays of massive stars in the Orion Nebula Cluster

2008 ◽  
Vol 4 (S259) ◽  
pp. 449-452 ◽  
Author(s):  
Véronique Petit ◽  
G. A. Wade ◽  
L. Drissen ◽  
T. Montmerle ◽  
E. Alecian
Keyword(s):  
Magnetic Fields ◽  
Massive Stars ◽  
Magnetic Confinement ◽  
Stellar Winds ◽  
X Rays ◽  
Orion Nebula ◽  
X Ray ◽  
Ob Stars ◽  
Complex Processes ◽  
The Relationship

AbstractIn massive stars, magnetic fields are thought to confine the outflowing radiatively-driven wind, resulting in X-ray emission that is harder, more variable and more efficient than that produced by instability-generated shocks in non-magnetic winds. Although magnetic confinement of stellar winds has been shown to strongly modify the mass-loss and X-ray characteristics of massive OB stars, we lack a detailed understanding of the complex processes responsible. The aim of this study is to examine the relationship between magnetism, stellar winds and X-ray emission of OB stars. In conjunction with a Chandra survey of the Orion Nebula Cluster, we carried out spectropolarimatric ESPaDOnS observations to determine the magnetic properties of massive OB stars of this cluster.

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 Evolution of massive stars, supergiants and Wolf-Rayet stars

1984 ◽  
Vol 105 ◽  
pp. 299-319
Author(s):  
André Maeder
Keyword(s):  
Interstellar Medium ◽  
Massive Stars ◽  
Stellar Winds ◽  
H Ii Regions ◽  
Chemical Interactions ◽  
Chemical Surface

Massive stars (say M ≳ 9 M⊙) play a major role in Astrophysics. They are the main agents of nucleosynthesis and galactic enrichment and present many interesting properties, like high stellar winds, chemical surface enhancements, instabilities etc. which deserve further investigation. Furthermore, massive stars also are the powering sources of giant H II regions and have important radiative, mechanical and chemical interactions with the interstellar medium.

scholarly journals Massive star evolution: from the early to the present day Universe

2008 ◽  
Vol 4 (S252) ◽  
pp. 317-327 ◽  
Author(s):  
Georges Meynet ◽  
Sylvia Ekström ◽  
Cyril Georgy ◽  
André Maeder ◽  
Raphael Hirschi
Keyword(s):  
Interstellar Medium ◽  
Mass Loss ◽  
Radiation Field ◽  
Massive Star ◽  
Massive Stars ◽  
Mechanical Energy ◽  
Axial Rotation ◽  
Star Evolution ◽  
Massive Star Evolution ◽  
Hr Diagram

AbstractMass loss and axial rotation are playing key roles in shaping the evolution of massive stars. They affect the tracks in the HR diagram, the lifetimes, the surface abundances, the hardness of the radiation field, the chemical yields, the presupernova status, the nature of the remnant, the mechanical energy released in the interstellar medium, etc. . . In this paper, after recalling a few characteristics of mass loss and rotation, we review the effects of these two processes at different metallicities. Rotation probably has its most important effects at low metallicities, while mass loss and rotation deeply affect the evolution of massive stars at solar and higher than solar metallicities.

scholarly journals The Violent Interstellar Medium of Nearby Dwarf Galaxies

1999 ◽  
Vol 16 (1) ◽  
pp. 106-112 ◽  
Author(s):  
Fabian Walter
Keyword(s):  
Interstellar Medium ◽  
Gamma Ray ◽  
Dwarf Galaxies ◽  
Young Star ◽  
Stellar Winds ◽  
Star Forming ◽  
Star Forming Regions ◽  
Supernova Explosions ◽  
High Velocity Clouds ◽  
Ob Associations

AbstractHigh resolution HI observations of nearby dwarf galaxies (most of which are situated in the M81 group at a distance of about 3·2 Mpc) reveal that their neutral interstellar medium (ISM) is dominated by hole-like features most of which are expanding. A comparison of the physical properties of these holes with the ones found in more massive spiral galaxies (such as M31 and M33) shows that they tend to reach much larger sizes in dwarf galaxies. This can be understood in terms of the galaxy's gravitational potential. The origin of these features is still a matter of debate. In general, young star forming regions (OB-associations) are held responsible for their formation. This picture, however, is not without its critics and other mechanisms such as the infall of high velocity clouds, turbulent motions or even gamma ray bursters have been recently proposed. Here I will present one example of a supergiant shell in IC 2574 which corroborates the picture that OB associations are indeed creating these structures. This particular supergiant shell is currently the most promising case to study the effects of the combined effects of stellar winds and supernova explosions which shape the neutral interstellar medium of (dwarf) galaxies.

scholarly journals What Do We Really Know About the Winds of Massive Stars?

2007 ◽  
Vol 3 (S250) ◽  
pp. 89-96
Author(s):  
D. John Hillier
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Standard Theory ◽  
Stellar Winds ◽  
X Rays ◽  
X Ray ◽  
Stellar Photosphere ◽  
Weak Winds ◽  
Ionization Balance ◽  
Loss Rates

AbstractThe standard theory of radiation driven winds has provided a useful framework to understand stellar winds arising from massive stars (O stars, Wolf-Rayet stars, and luminous blue variables). However, with new diagnostics, and advances in spectral modeling, deficiencies in our understanding of stellar winds have been thrust to the forefront of our research efforts. Spectroscopic observations and analyses have shown the importance of inhomogeneities in stellar winds, and revealed that there are fundamental discrepancies between predicted and theoretical mass-loss rates. For late O stars, spectroscopic analyses derive mass-loss rates significantly lower than predicted. For all O stars, observed X-ray fluxes are difficult to reproduce using standard shock theory, while observed X-ray profiles indicate lower mass-loss rates, the potential importance of porosity effects, and an origin surprisingly close to the stellar photosphere. In O stars with weak winds, X-rays play a crucial role in determining the ionization balance, and must be taken into account.

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