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Large scale kinematics and dynamical modelling of the Milky Way nuclear star cluster

Titulo: 
Large scale kinematics and dynamical modelling of the Milky Way nuclear star cluster
Autores: 
Feldmeier, A; Neumayer, N; Seth, A; Schodel, R; Lutzgendorf, N; de Zeeuw, PT; Kissler-Patig, M; Nishiyama, S; Walcher, CJ
Resumen: 
Context. Within the central 10 pc of our Galaxy lies a dense cluster of stars. This nuclear star cluster forms a distinct component of the Galaxy, and similar nuclear star clusters are found in most nearby spiral and elliptical galaxies. Studying the structure and kinematics of nuclear star clusters reveals the history of mass accretion and growth of galaxy nuclei and central massive black holes. Aims. Because the Milky Way nuclear star cluster is at a distance of only 8 kpc, we can spatially resolve the cluster on sub-parsec scales. This makes the Milky Way nuclear star cluster a reference object for understanding the formation of all nuclear star clusters. Methods. We have used the near-infrared long-slit spectrograph ISAAC (VLT) in a drift-scan to construct an integral-field spectroscopic map of the central similar to 9.5 x 8 pc of our Galaxy, and six smaller fields out to 19 pc along the Galactic plane. We use this spectroscopic data set to extract stellar kinematics both of individual stars and from the unresolved integrated light spectrum. We present a velocity and dispersion map from the integrated light spectra and model these kinematics using kinemetry and axisymmetric Jeans models. We also measure radial velocities and CO bandhead strengths of 1375 spectra from individual stars. Results. We find kinematic complexity in the nuclear star clusters radial velocity map including a misalignment of the kinematic position angle by 9 degrees counterclockwise relative to the Galactic plane, and indications for a rotating substructure perpendicular to the Galactic plane at a radius of 20 '' or similar to 0.8 pc. We determine the mass of the nuclear star cluster within r = 4.2 pc to (1.4(-0.47)(+0.6)) x 10(7) M-circle dot. We also show that our kinematic data results in a significant underestimation of the supermassive black hole (SMBH) mass. Conclusions. The kinematic substructure and position angle misalignment may hint at distinct accretion events. This indicates that the MilkyWay nuclear star cluster grew at least partly by the mergers of massive star clusters. Compared to other nuclear star clusters, the Milky Way nuclear star cluster is on the compact side of the r(eff) - M-NSC relation. The underestimation of the SMBH mass might be caused by the kinematic misalignment and a stellar population gradient. But it is also possible that there is a bias in SMBH mass measurements obtained with integrated light, and this might affect SMBH mass determinations of other galaxies.
Autor principal: 
Feldmeier, A
Autor/es del IAA: 
Schoedel, R.
DOI: 
10.1051/0004-6361/201423777
Revista: 
ASTRONOMY & ASTROPHYSICS
Fecha de publicación: 
2014/10
Volumen: 
570
Tipo de documento: 
Article
Palabras clave: 
Galaxy: nucleus; Galaxy: kinematics and dynamics
Número de artículo: 
A2

Stellar population gradients in galaxy discs from the CALIFA survey

Titulo: 
Stellar population gradients in galaxy discs from the CALIFA survey
Autores: 
Sanchez-Blazquez, P; Rosales-Ortega, FF; Mendez-Abreu, J; Perez, I; Sanchez, SF; Zibetti, S; Aguerri, JAL; Bland-Hawthorn, J; Catalan-Torrecilla, C; Fernandes, RC; de Amorim, A; de Lorenzo-Caceres, A; Falcon-Barroso, J; Galazzi, A; Benito, RG; de Paz, AG; Delgado, RG; Husemann, B; Iglesias-Paramo, J; Jungwiert, B; Marino, RA; Marquez, I; Mast, D; Mendoza, MA; Molla, M; Papaderos, P; Ruiz-Lara, T; van de Ven, G; Walcher, CJ; Wisotzki, L
Resumen: 
While studies of gasphase metallicity gradients in disc galaxies are common, very little has been done towards the acquisition of stellar abundance gradients in the same regions. We present here a comparative study of the stellar metallicity and age distributions in a sample of 62 nearly face-on, spiral galaxies with and without bars, using data from the CALIFA survey. We measure the slopes of the gradients and study their relation with other properties of the galaxies. We find that the mean stellar age and metallicity gradients in the disc are shallow and negative. Furthermore, when normalized to the effective radius of the disc, the slope of the stellar population gradients does not correlate with the mass or with the morphological type of the galaxies. In contrast to this, the values of both age and metallicity at similar to 2.5 scale lengths correlate with the central velocity dispersion in a similar manner to the central values of the bulges, although bulges show, on average, older ages and higher metallicities than the discs. One of the goals of the present paper is to test the theoretical prediction that non-linear coupling between the bar and the spiral arms is an efficient mechanism for producing radial migrations across significant distances within discs. The process of radial migration should flatten the stellar metallicity gradient with time and, therefore, we would expect flatter stellar metallicity gradients in barred galaxies. However, we do not find any difference in the metallicity or age gradients between galaxies with and without bars. We discuss possible scenarios that can lead to this lack of difference.
Autor principal: 
Sanchez-Blazquez, P
Autor/es del IAA: 
Sanchez, S. F.; de Amorim, A.; Garcia Benito, R.; Gonzalez Delgado, R.; Husemann, B.; Marquez, I.; Mendoza, M. A.
DOI: 
10.1051/0004-6361/201423635
Revista: 
ASTRONOMY & ASTROPHYSICS
Fecha de publicación: 
2014/10
Volumen: 
570
Tipo de documento: 
Article
Palabras clave: 
galaxies: abundances; galaxies: evolution; galaxies: formation; galaxies: spiral; galaxies: stellar content

The Gaia-ESO Survey: The analysis of high-resolution UVES spectra of FGK-type stars

Titulo: 
The Gaia-ESO Survey: The analysis of high-resolution UVES spectra of FGK-type stars
Autores: 
Smiljanic, R; Korn, AJ; Bergemann, M; Frasca, A; Magrini, L; Masseron, T; Pancino, E; Ruchti, G; San Roman, I; Sbordone, L; Sousa, SG; Tabernero, H; Tautvaisiene, G; Valentini, M; Weber, M; Worley, CC; Adibekyan, VZ; Prieto, CA; Barisevicius, G; Biazzo, K; Blanco-Cuaresma, S; Bonifacio, P; Bragaglia, A; Caffau, E; Cantat-Gaudin, T; Chorniy, Y; de Laverny, P; Delgado-Mena, E; Donati, P; Duffau, S; Franciosini, E; Friel, E; Geisler, D; Hernandez, JIG; Gruyters, P; Guiglion, G; Hansen, CJ; Heiter, U; Hill, V; Jacobson, HR; Jofre, P; Jonsson, H; Lanzafame, AC; Lardo, C; Ludwig, HG; Maiorca, E; Mikolaitis, S; Montes, D; Morel, T; Mucciarelli, A; Munoz, C; Nordlander, T; Pasquini, L; Puzeras, E; Recio-Blanco, A; Ryde, N; Sacco, G; Santos, NC; Serenelli, AM; Sordo, R; Soubiran, C; Spina, L; Steffen, M; Vallenari, A; Van Eck, S; Villanova, S; Gilmore, G; Randich, S; Asplund, M; Binney, J; Drew, J; Feltzing, S; Ferguson, A; Jeffries, R; Micela, G; Negueruela, I; Prusti, T; Rix, HW; Alfaro, E; Babusiaux, C; Bensby, T; Blomme, R; Flaccomio, E; Francois, P; Irwin, M; Koposov, S; Walton, N; Bayo, A; Carraro, G; Costado, MT; Damiani, F; Edvardsson, B; Hourihane, A; Jackson, R; Lewis, J; Lind, K; Marconi, G; Martayan, C; Monaco, L; Morbidelli, L; Prisinzano, L; Zaggia, S
Resumen: 
Context. The ongoing Gaia-ESO Public Spectroscopic Survey is using FLAMES at the VLT to obtain high-quality medium-resolution Giraffe spectra for about 10(5) stars and high-resolution UVES spectra for about 5000 stars. With UVES, the Survey has already observed 1447 FGK-type stars. Aims. These UVES spectra are analyzed in parallel by several state-of-the-art methodologies. Our aim is to present how these analyses were implemented, to discuss their results, and to describe how a final recommended parameter scale is defined. We also discuss the precision (method-to-method dispersion) and accuracy (biases with respect to the reference values) of the final parameters. These results are part of the Gaia-ESO second internal release and will be part of its first public release of advanced data products. Methods. The final parameter scale is tied to the scale defined by the Gaia benchmark stars, a set of stars with fundamental atmospheric parameters. In addition, a set of open and globular clusters is used to evaluate the physical soundness of the results. Each of the implemented methodologies is judged against the benchmark stars to define weights in three different regions of the parameter space. The final recommended results are the weighted medians of those from the individual methods. Results. The recommended results successfully reproduce the atmospheric parameters of the benchmark stars and the expected T-eff-log g relation of the calibrating clusters. Atmospheric parameters and abundances have been determined for 1301 FGK-type stars observed with UVES. The median of the method-to-method dispersion of the atmospheric parameters is 55K for T-eff, 0.13dex for log g and 0.07 dex for [Fe/H]. Systematic biases are estimated to be between 50-100 K for T-eff, 0.10-0.25 dex for log g and 0.05-0.10 dex for [Fe/H]. Abundances for 24 elements were derived: C, N, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mo, Ba, Nd, and Eu. The typical method-to-method dispersion of the abundances varies between 0.10 and 0.20 dex. Conclusions. The Gaia-ESO sample of high-resolution spectra of FGK-type stars will be among the largest of its kind analyzed in a homogeneous way. The extensive list of elemental abundances derived in these stars will enable significant advances in the areas of stellar evolution and Milky Way formation and evolution.
Autor principal: 
Smiljanic, R
Autor/es del IAA: 
Alfaro, E.; Costado, M. T.
DOI: 
10.1051/0004-6361/201423937
Revista: 
ASTRONOMY & ASTROPHYSICS
Fecha de publicación: 
2014/10
Volumen: 
570
Tipo de documento: 
Article
Palabras clave: 
methods: data analysis; surveys; stars: abundances; stars: fundamental parameters; stars: late-type
Número de artículo: 
A122

GTC spectra of z approximate to 2.3 quasars: comparison with local luminosity analogs

Titulo: 
GTC spectra of z approximate to 2.3 quasars: comparison with local luminosity analogs
Autores: 
Sulentic, JW; Marziani, P; del Olmo, A; Dultzin, D; Perea, J; Negrete, CA
Resumen: 
Context. The advent of 8-10 m class telescopes for the first time makes it possible to compare in detail quasars with similar luminosity and very different redshifts. Aims. We conducted a search for z-dependent gradients in line-emission diagnostics and derived physical properties by comparing, in a narrow bolometric luminosity range (log L similar to 46.1 +/- 0.4 [erg s(-1)]), some of the most luminous local z < 0.6 quasars with some of the lowest luminosity sources yet found at redshift z = 2.1-2.5. Methods. Moderate signal-to-noise ratio spectra for 22 high-redshift sources were obtained with the 10.4 m Gran Telescopio Canarias (GTC), for which the HST (largely the Faint Object Spectrograph) archive provides a low-redshift control sample. We compared the spectra in the context of the 4D Eigenvector 1 formalism, meaning that we divided both source samples into highly accreting population A and population B sources accreting at a lower rate. Results. CIV lambda 1549, the strongest and most reliable diagnostic line, shows very similar properties at both redshifts, which confirms the CIV lambda 1549 profile differences at high redshift between populations A and B, which are well established in local quasars. The CIV lambda 1549 blueshift that appears quasi-ubiquitous in higher L sources is found in only half (population A) of the quasars observed in the two samples. A CIV lambda 1549 evolutionary Baldwin effect is certainly disfavored. We find evidence for lower metallicity in the GTC sample that may point toward a gradient with z. No evidence for a gradient in M-BH or L/L-Edd is found. Conclusions. Spectroscopic differences established at low z are also present in much higher redshift quasars. Our results on the CIV lambda 1549 blueshift suggest that it depends both on source luminosity and L/L-Edd. Given that our samples involve sources with very similar luminosity, the evidence for a systematic metallicity decrease, if real, points toward an evolutionary effect. Our samples are not large enough to effectively constrain possible changes of M-BH or L/L-Edd with redshift. The two samples appear representative of a slowly evolving quasar population that is most likely present at all redshifts.
Autor principal: 
Sulentic, JW
Autor/es del IAA: 
Sulentic, Jack W.; del Olmo, Ascension; Perea, Jaime
DOI: 
10.1051/0004-6361/201423975
Revista: 
ASTRONOMY & ASTROPHYSICS
Fecha de publicación: 
2014/10
Volumen: 
570
Tipo de documento: 
Article
Palabras clave: 
quasars: emission lines; quasars: supermassive black holes; ISM: abundances; line: profiles; cosmology: observations

Molecular line emission in NGC 1068 imaged with ALMA II. The chemistry of the dense molecular gas

Titulo: 
Molecular line emission in NGC 1068 imaged with ALMA II. The chemistry of the dense molecular gas
Autores: 
Viti, S; Garcia-Burillo, S; Fuente, A; Hunt, LK; Usero, A; Henkel, C; Eckart, A; Martin, S; Spaans, M; Muller, S; Combes, F; Krips, M; Schinnerer, E; Casasola, V; Costagliola, F; Marquez, I; Planesas, P; van der Werf, PP; Aalto, S; Baker, AJ; Boone, F; Tacconi, LJ
Resumen: 
Aims. We present a detailed analysis of Atacama Large Millimeter/submillimeter Array (ALMA) Bands 7 and 9 data of CO, HCO+, HCN, and CS, augmented with Plateau de Bure Interferometer (PdBI) data of the similar to 200 pc circumnuclear disc (CND) and the similar to 1.3 kpc starburst ring (SB ring) of NGC 1068, a nearby (D = 14 Mpc) Seyfert 2 barred galaxy. We aim to determine the physical characteristics of the dense gas present in the CND, and to establish whether the different line intensity ratios we find within the CND, as well as between the CND and the SB ring, are due to excitation effects (gas density and temperature differences) or to a different chemistry. Methods. We estimate the column densities of each species in local thermodynamic equilibrium (LTE). We then compute large one-dimensional, non-LTE radiative transfer grids (using RADEX) by using only the CO transitions first, and then all the available molecules to constrain the densities, temperatures, and column densities within the CND. We finally present a preliminary set of chemical models to determine the origin of the gas. Results. We find that, in general, the gas in the CND is very dense (> 10(5) cm(-3)) and hot (T > 150 K), with differences especially in the temperature across the CND. The AGN position has the lowest CO/HCO+, CO/HCN, and CO/CS column density ratios. The RADEX analyses seem to indicate that there is chemical differentiation across the CND. We also find differences between the chemistry of the SB ring and some regions of the CND; the SB ring is also much colder and less dense than the CND. Chemical modelling does not succeed in reproducing all the molecular ratios with one model per region, suggesting the presence of multi-gas phase components. Conclusions. The LTE, RADEX, and chemical analyses all indicate that more than one gas-phase component is necessary to uniquely fit all the available molecular ratios within the CND. A higher number of molecular transitions at the ALMA resolution is necessary to determine quantitatively the physical and chemical characteristics of these components.
Autor principal: 
Viti, S
Autor/es del IAA: 
Costagliola, F.; Marquez, I.
DOI: 
10.1051/0004-6361/201424116
Revista: 
ASTRONOMY & ASTROPHYSICS
Fecha de publicación: 
2014/10
Volumen: 
570
Tipo de documento: 
Article
Palabras clave: 
galaxies: active; galaxies: individual: NGC 1068; galaxies: ISM; galaxies: nuclei; molecular processes; radio lines: galaxies
Número de artículo: 
A28

THE FORMATION AND DISINTEGRATION OF MAGNETIC BRIGHT POINTS OBSERVED BY SUNRISE/IMaX

Titulo: 
THE FORMATION AND DISINTEGRATION OF MAGNETIC BRIGHT POINTS OBSERVED BY SUNRISE/IMaX
Autores: 
Utz, D; Iniesta, JCDT; Rubio, LRB; Jurcak, J; Pillet, VM; Solanki, SK; Schmidt, W
Resumen: 
The evolution of the physical parameters of magnetic bright points (MBPs) located in the quiet Sun (mainly in the interwork) during their lifetime is studied. First, we concentrate on the detailed description of the magnetic field evolution of three MBPs. This reveals that individual features follow different, generally complex, and rather dynamic scenarios of evolution. Next, we apply statistical methods on roughly 200 observed MBP evolutionary tracks. MBPs are found to be formed by the strengthening of an equipartition field patch, which initially exhibits a moderate downflow. During the evolution, strong downdrafts with an average velocity of 2.4 km s(-1) set in. These flows, taken together with the concurrent strengthening of the field, suggest that we are witnessing the occurrence of convective collapses in these features, although only 30% of them reach kG field strengths. This fraction might turn out to be larger when the new 4mclass solar telescopes are operational as observations of MBPs with current state of the art instrumentation could still be suffering from resolution limitations. Finally, when the bright point disappears (although the magnetic field often continues to exist) the magnetic field strength has dropped to the equipartition level and is generally somewhat weaker than at the beginning of the MBP's evolution. Also, only relatively weak downflows are found on average at this stage of the evolution. Only 16% of the features display upflows at the time that the field weakens, or the MBP disappears. This speaks either for a very fast evolving dynamic process at the end of the lifetime, which could not be temporally resolved, or against strong upflows as the cause of the weakening of the field of these magnetic elements, as has been proposed based on simulation results. It is noteworthy that in about 10% of the cases, we observe in the vicinity of the downflows small-scale strong (exceeding 2 km s-1) intergranular upflows related spatially and temporally to these downflows. The paper is complemented by a detailed discussion of aspects regarding the applied methods, the complementary literature, and in depth analysis of parameters like magnetic field strength and velocity distributions. An important difference to magnetic elements and associated bright structures in active region plage is that most of the quiet Sun bright points display significant downflows over a large fraction of their lifetime (i.e., in more than 46% of time instances/measurements they show downflows exceeding 1 km s(-1)).
Autor principal: 
Utz, D
Autor/es del IAA: 
Utz, D.; Iniesta, J. C. del Toro; Rubio, L. R. Bellot
DOI: 
10.1088/0004-637X/796/2/79
Revista: 
ASTROPHYSICAL JOURNAL
Fecha de publicación: 
2014/12/01
Volumen: 
796
Issue: 
2
Tipo de documento: 
Article
Palabras clave: 
instrumentation: high angular resolution; instrumentation: polarimeters; Sun: magnetic fields; Sun: photosphere; techniques: imaging spectroscopy
Número de artículo: 
79

Wind circulation regimes at Venus' cloud tops: Ground-based Doppler velocimetry using CFHT/ESPaDOnS and comparison with simultaneous cloud tracking measurements using VEx/VIRTIS in February 2011

Titulo: 
Wind circulation regimes at Venus' cloud tops: Ground-based Doppler velocimetry using CFHT/ESPaDOnS and comparison with simultaneous cloud tracking measurements using VEx/VIRTIS in February 2011
Autores: 
Machado, P; Widemann, T; Luz, D; Peralta, J
Resumen: 
We present new results based on ground-based Doppler spectroscopic measurements, obtained with the ESPaDOnS spectrograph at Canada-France-Hawaii telescope (CFHT) and simultaneous observations of velocity fields, obtained from space by the VIRTIS-M instrument on board the Venus Express spacecraft. These measurements are based on high-resolution spectra of Fraunhofer lines in the visible to NIR range (0.37-1.05 mu m) acquired on February 19-21, 2011 at a resolution of about 80,000, measuring Venus' winds at 70 km, using incoming solar radiation scattered by cloud top particles in the observer's direction (Widemann, T., et al., [2007]. Planet. Space Sci. 55, 1741-1756; Widemann, T., et al., [2008]. Planet. Space Sci. 56, 1320-1334). The zonal wind field has been characterized by latitudinal bands, at a phase angle Phi = (68.7 +/- 0.3)degrees, between +10 degrees N and 60 degrees S, by steps of 10 degrees, and from [phi - phi(E)] = -50 degrees to sub-Earth longitude phi(E) = 0 degrees, by steps of 12 degrees. From space, VIRTIS-M UV (0.38 mu m) imaging exposures on the dayside were acquired simultaneously in orbit 1786, providing the first simultaneous cloud-tracking measurements with Doppler velocimetry. From the ground, we measured a zonal mean background velocity of (nu) over bar (z)= (117.3 +/- 18.0) m s(-1) on February 19, and (nu) over bar (z) = (117.5 +/- 14.5) m s(-1) on February 21. We detect an unambiguous poleward meridional flow on the morning dayside hemisphere of (18.8 +/- 12.3) m s(-1) on February 19/21. Latitudinal variations of the zonal and meridional winds are further compared with the simultaneous VIRTIS data. We discuss temporal variability as well as its statistical significance. (C) 2014 Elsevier Inc. All rights reserved.
Autor principal: 
Machado, P
Autor/es del IAA: 
Peralta, Javier
DOI: 
10.1016/j.icarus.2014.08.030
Revista: 
ICARUS
Fecha de publicación: 
2014/11/15
Volumen: 
243
Páginas: 
249-263
Tipo de documento: 
Article
Palabras clave: 
Venus, atmosphere; Atmospheres, dynamics; Spectroscopy

Effect of Amorphous Ammonia-Water Ice onto Adsorption of Glycine on Cometary Dust Grain and IR Spectroscopy

Titulo: 
Effect of Amorphous Ammonia-Water Ice onto Adsorption of Glycine on Cometary Dust Grain and IR Spectroscopy
Autores: 
Escamilla-Roa, E; Sainz-Diaz, CI
Resumen: 
The extraterrestrial origin of glycine has become a topic of great interest for astrobiology and it has been detected bonded to mineral surfaces in the dust of comet 81P/Wild 2 by the Stardust mission. The interactions of organic molecules with the dust grain surfaces shed light on possible routes for life from extraterrestrial space to Earth. The NH3 is one of the volatile components of cometary and interstellar ices. In this work we propose models that describe this scenario that consist of a quaternary system of one glycine molecule, a mixture of amorphous ammoniawater ice, and forsterite (100) surfaces (dipolar and nondipolar). Our quantum mechanical calculations show that the presence of amorphous ammonia/water ice increases the adsorption energy of glycine on the forsterite surface with respect to only amorphous water ice. In addition, we calculated the infrared (IR) frequencies to characterize the most reactive sites in the chemisorption processes with the mineral surface.
Autor principal: 
Escamilla-Roa, E
Autor/es del IAA: 
Escamilla-Roa, Elizabeth
DOI: 
10.1021/jp507650w
Revista: 
JOURNAL OF PHYSICAL CHEMISTRY C
Fecha de publicación: 
2014/11/13
Volumen: 
118
Issue: 
45
Páginas: 
26080-26090
Tipo de documento: 
Article

Transient Upper Atmospheric Plasmas:Sprites and Halos

Titulo: 
Transient Upper Atmospheric Plasmas:Sprites and Halos
Autores: 
Passas, M; del Rio, JS; Luque, A; Gordillo-Vazquez, FJ
Resumen: 
Sprites and halos are two types of the so-called transient luminous events occurring in the upper layers (40-90 km) of the earth atmosphere. Their spectacular appearance is due to the optical emissions from mesospheric plasmas caused by the electric breakdown of the high-altitude rarified air. While halos look like flattened diffuse flashes of light appearing between 80 and 85 km, sprites exhibit a sharp transition between the upper diffuse and lower plasma streamer regions, as observed in one of the images shown here.
Autor principal: 
Passas, M
Autor/es del IAA: 
Passas, Maria; Sanchez del Rio, Justo; Luque, Alejandro; Gordillo-Vazquez, Francisco J.
DOI: 
10.1109/TPS.2014.2329320
Revista: 
IEEE TRANSACTIONS ON PLASMA SCIENCE
Fecha de publicación: 
2014/10
Volumen: 
42
Issue: 
10
Páginas: 
2664-2665
Tipo de documento: 
Article
Palabras clave: 
Geophysics; geoscience and remote sensing; meteorology; nuclear and plasma sciences; plasmas

The nuclear cluster of the Milky Way: our primary testbed for the interaction of a dense star cluster with a massive black hole

Titulo: 
The nuclear cluster of the Milky Way: our primary testbed for the interaction of a dense star cluster with a massive black hole
Autores: 
Schodel, R; Feldmeier, A; Neumayer, N; Meyer, L; Yelda, S
Resumen: 
This article intends to provide a concise overview, from an observational point-of-view, of the current state of our knowledge of the most relevant properties of the Milky Way's nuclear star cluster (MWNSC). The MWNSC appears to be a typical specimen of nuclear star clusters, which are found at the centers of the majority of all types of galaxies. Nuclear clusters represent the densest and most massive stellar systems in the present-day Universe and frequently coexist with central massive black holes. They are therefore of prime interest for studying stellar dynamics, and the MWNSC is the only one that allows us to obtain data on milli-parsec scales. After discussing the main observational constraints, we start with a description of the overall structure and kinematics of the MWNSC, then focus on a comparison to extragalactic systems, summarize the properties of the young, massive stars in the immediate environment of the Milky Way's central black hole, Sagittarius A*, and finally focus on the dynamics of stars orbiting the black hole at distances of a few to a few tens of milli parsecs.
Autor principal: 
Schodel, R
Autor/es del IAA: 
Schoedel, R.
DOI: 
10.1088/0264-9381/31/24/244007
Revista: 
CLASSICAL AND QUANTUM GRAVITY
Fecha de publicación: 
2014/12/21
Volumen: 
31
Issue: 
24
Tipo de documento: 
Article
Palabras clave: 
Milky Way: center; nuclear star clusters; massive black holes; star clusters; observations: high angular resolution; observations: infrared
Número de artículo: 
244007

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