Massive Stars in the Arches Cluster

Figer, Donald F.; Najarro, F.; Gilmore, Diane; Morris, Mark; Kim, Sungsoo S.; Serabyn, Eugene; McLean, Ian S.; Gilbert, Andrea M.; Graham, James R.; Larkin, James E.; Levenson, N. A.; Teplitz, Harry I.

doi:10.1086/344154

Cited by 304 publications

(391 citation statements)

References 58 publications

(82 reference statements)

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“…The age of the Arches cluster is estimated as 3.5 ± 0.7 Myr and the Quintuplet cluster as 4.8 ± 1.1 Myr (see Schneider et al 2014) thus supporting the idea of a number of local starburst events in the Galactic Center neighbourhood during the last 10 Myrs. The ionizing photon luminosity of the Arches cluster is about 4×10 51 photons s −1 with the total luminosity of about 6× 10 7 L and its stellar IMF appears to be of "top-heavy" type for the cluster with the estimated index α ∼ 1.6 ± 0.1 (Figer et al 2002), which is similar to that of NGC 3603. The Arches cluster is very compact, its radius is about 0.2 pc providing a very high mass density 3×10 5 M pc −3 , while the size of the Quintuplet star cluster is about a parsec.…”

Section: Galactic Center Clustersmentioning

confidence: 67%

Nonthermal particles and photons in starburst regions and superbubbles

Bykov

2014

Astron Astrophys Rev

109

100

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Starforming factories in galaxies produce compact clusters and loose associations of young massive stars. Fast radiation-driven winds and supernovae input their huge kinetic power into the interstellar medium in the form of highly supersonic and superalfvenic outflows. Apart from gas heating, collisionless relaxation of fast plasma outflows results in fluctuating magnetic fields and energetic particles. The energetic particles comprise a long-lived component which may contain a sizeable fraction of the kinetic energy released by the winds and supernova ejecta and thus modify the magnetohydrodynamic flows in the systems. We present a concise review of observational data and models of nonthermal emission from starburst galaxies, superbubbles, and compact clusters of massive stars. Efficient mechanisms of particle acceleration and amplification of fluctuating magnetic fields with a wide dynamical range in starburst regions are discussed. Sources of cosmic rays, neutrinos and multi-wavelength nonthermal emission associated with starburst regions including potential galactic "PeVatrons" are reviewed in the global galactic ecology context.

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Section: Galactic Center Clustersmentioning

confidence: 67%

Nonthermal particles and photons in starburst regions and superbubbles

Bykov

2014

Astron Astrophys Rev

109

100

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“…Figer et al 2002;Crowther et al 2002;Hillier et al 2003;Bouret et al 2003;Repolust et al 2004;Markova et al 2004;Bouret et al 2005;Fullerton et al 2006). This implies that empirical mass-loss rates may have to be scaled down by factors 2-10.…”

Section: Introductionmentioning

confidence: 99%

Predictions of the effect of clumping on the wind properties of O-type stars

Muijres

Koter

Vink

et al. 2010

A&A

100

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Aims. Both empirical evidence and theoretical findings indicate that the stellar winds of massive early-type stars are inhomogeneous, i.e., porous and clumpy. For relatively dense winds, empirically derived mass-loss rates might be reconciled with predictions if these empirical rates are corrected for clumping. The predictions, however, do not account for structure in the wind. To allow for a consistent comparison, we investigate and quantify the effect of clumpiness and porosity of the outflow on the predicted wind energy and the maximal effect on the mass-loss rate of O-type stars. Methods. Combining non-LTE model atmospheres and a Monte Carlo method to compute the transfer of momentum from the photons to the gas, the effect of clumping and porosity on the energy transferred from the radiation field to the wind is computed in outflows in which the clumping and porosity stratification is parameterized by heuristic prescriptions. Results. The impact of structure in the outflow on the wind energy is complex and is a function of stellar temperature, the density of gas in the clumps, and the physical scale of the clumps. If the medium is already clumped in the photosphere, the emergent radiation field will be softer, slightly increasing the wind energy of relatively cool O stars (30 000 K) but slightly decreasing it for relatively hot O stars (40 000 K). More important is that as a result of recombination of the gas in a clumped wind the line force increases. However, because of porosity the line force decreases, simply because photons may travel in-between the clumps, avoiding interactions with the gas. If the changes in the wind energy only affect the mass-loss rate and not the terminal velocity of the flow, we find that the combined effect of clumpiness and porosity is a small reduction in the mass-loss rate if the clumps are smaller than 1/100th the local density scale height H ρ . In this case, empirical mass-loss determinations based on Hα fitting and theory match for stars with dense winds (Ṁ > ∼ 10 −7 M yr −1 ) if the overdensity of gas in the clumps, relative to the case of a smooth wind, is modest. For clumps larger than 1/10th H ρ , the predicted mass-loss rates exhibit almost the same dependence on clumpiness as do empirical rates. We show that this implies that empirical and predicted mass-loss rates can no longer be matched. Very high overdensities of gas in clumps of such large size may cause the predictedṀ to decrease by a factor of from 10 to 100. This type of structure is likely not to be the cause of the "weak-wind problem" in early-type stars, unless a mechanism can be identified that causes extreme structure to develop in winds for whichṀ < ∼ 10 −7 M yr −1 (weak winds) that is not active in denser winds.

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“…CWB system WR25 is a near twin of CXO J1745-28. Moreover, it appears difficult to reconcile both the youth and extreme mass inferred for CXO J1745-28 and the Arches sources with the requirement for a SN to have occurred in order to yield a relativistic companion − however we note that if they are HMXBs then they will provide a unique insight into the final The cluster list follows that of Crowther et al (2006), supplemented with the WNLh rich Arches (Figer et al 2002) and 30 Dor (Walborn & Blades 1989) clusters. Column 4 summarises the number of stars in each cluster for which a RV survey has been carried out.…”

Section: Discussion and Concluding Remarksmentioning

confidence: 88%

The binary nature of the Galactic centre X-ray source CXOGC J174536.1-285638

Clark

Crowther

Mikles

2009

A&A

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Context. The combination of X-ray and near-IR surveys of the central 2 o × 0.8 o of the Galactic centre have revealed a population of X-ray bright massive stars. However, the nature of the X-ray emission, originating in wind collision zones or via accretion onto compact objects, is uncertain. Aims. In order to address this we investigated the nature of one of the most luminous X-ray sources − CXOGC J174536.1-285638. Methods. This was accomplished by an analysis of the near-IR spectrum with a non-LTE model atmosphere code to determine the physical parameters of the primary.Results. This was found to be an highly luminous WN9h star, which is remarkably similar to the most massive stars found in the Arches cluster, for which comparison to evolutionary tracks suggest an age of 2-2.5 Myr and an initial mass of ∼110 M . The X-ray properties of CXOGC J174536.1-285638 also resemble those of 3 of the 4 X-ray detected WN9h stars within the Arches and in turn other very massive WNLh colliding wind binaries, of which WR25 forms an almost identical "twin". Simple analytical arguments demonstrate consistency between the X-ray emission and a putative WN9h+mid O V-III binary, causing us to favour such a scenario over an accreting binary. However, we may not exclude a high mass X-ray binary interpretation, which, if correct, would provide a unique insight into the (post-SN) evolution of extremely massive stars. Irrespective of the nature of the secondary, CXOGC J174536.1-285638 adds to the growing list of known and candidate WNLh binaries. Of the subset of WNLh stars subject to a radial velocity survey, we find a lower limit to the binary fraction of ∼45%; of interest for studies of massive stellar formation, given that they currently possess the highest dynamically determined masses of any type of star.

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Massive Stars in the Arches Cluster

Cited by 304 publications

References 58 publications

Nonthermal particles and photons in starburst regions and superbubbles

Nonthermal particles and photons in starburst regions and superbubbles

Predictions of the effect of clumping on the wind properties of O-type stars

The binary nature of the Galactic centre X-ray source CXOGC J174536.1-285638

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