53756
2017
2017
eng
5591
5616
26
4
473
article
Oxford Univ. Press
Oxford
1
2017-10-23
2017-10-23
--
A stellar census in globular clusters with MUSE
This is the first of a series of papers presenting the results from our survey of 25 Galactic globular clusters with the MUSE integral-field spectrograph. In combination with our dedicated algorithm for source deblending, MUSE provides unique multiplex capabilities in crowded stellar fields and allows us to acquire samples of up to 20 000 stars within the half-light radius of each cluster. The present paper focuses on the analysis of the internal dynamics of 22 out of the 25 clusters, using about 500 000 spectra of 200 000 individual stars. Thanks to the large stellar samples per cluster, we are able to perform a detailed analysis of the central rotation and dispersion fields using both radial profiles and two-dimensional maps. The velocity dispersion profiles we derive show a good general agreement with existing radial velocity studies but typically reach closer to the cluster centres. By comparison with proper motion data, we derive or update the dynamical distance estimates to 14 clusters. Compared to previous dynamical distance estimates for 47 Tuc, our value is in much better agreement with other methods. We further find significant (>3 sigma) rotation in the majority (13/22) of our clusters. Our analysis seems to confirm earlier findings of a link between rotation and the ellipticities of globular clusters. In addition, we find a correlation between the strengths of internal rotation and the relaxation times of the clusters, suggesting that the central rotation fields are relics of the cluster formation that are gradually dissipated via two-body relaxation.
Monthly notices of the Royal Astronomical Society
the contribution of rotation to cluster dynamics studied with 200 000 stars
10.1093/mnras/stx2719
0035-8711
1365-2966
wos:2018
WOS:000424117300092
Kamann, S (reprint author), Georg August Univ, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany.; Kamann, S (reprint author), Liverpool John Moores Univ, Astrophys Res Inst, 146 Brownlow Hill, Liverpool L3 5RF, Merseyside, England., s.kamann@ljmu.ac.uk
German Ministry for Education and Science (BMBF Verbundforschung) through project MUSE-AO [05A14BAC, 05A14MGA, 05A17MGA]; German Research Foundation (DFG)German Research Foundation (DFG) [KA 4537/2-1, DR 281/35-1]; ESO Telescopes at the La Silla Paranal Observatory [094.D-0142, 095.D-0629, 096.D-0175, 097.D-0295]; NASANational Aeronautics & Space Administration (NASA) [NAS 5-26555]
2022-02-04T10:20:27+00:00
sword
importub
filename=package.tar
7c6b3ec9e5c9d4e7844684460587854b
Kamann, Sebastian
false
true
Sebastian Kamann
T. -O. Husser
S. Dreizler
E. Emsellem
Peter Michael Weilbacher
S. Martens
R. Bacon
M. den Brok
B. Giesers
Davor Krajnovic
Martin M. Roth
Martin Wendt
Lutz Wisotzki
eng
uncontrolled
techniques: imaging spectroscopy
eng
uncontrolled
stars: kinematics and dynamics
eng
uncontrolled
globular clusters: general
Astronomie und zugeordnete Wissenschaften
Physik
Institut für Physik und Astronomie
Referiert
Import
Green Open-Access
48495
2019
2019
eng
17
628
article
EDP Sciences
Les Ulis
1
--
2019-07-10
--
PG 1610+062: a runaway B star challenging classical ejection mechanisms
Hypervelocity stars are rare objects, mostly main-sequence (MS) B stars, traveling so fast that they will eventually escape from the Milky Way. Recently, it has been shown that the popular Hills mechanism, in which a binary system is disrupted via a close encounter with the supermassive black hole at the Galactic center, may not be their only ejection mechanism. The analyses of Gaia data ruled out a Galactic center origin for some of them, and instead indicated that they are extreme disk runaway stars ejected at velocities exceeding the predicted limits of classical scenarios (dynamical ejection from star clusters or binary supernova ejection). We present the discovery of a new extreme disk runaway star, PG 1610+062, which is a slowly pulsating B star bright enough to be studied in detail. A quantitative analysis of spectra taken with ESI at the Keck Observatory revealed that PG 1610+062 is a late B-type MS star of 4–5 M⊙ with low projected rotational velocity. Abundances (C, N, O, Ne, Mg, Al, Si, S, Ar, and Fe) were derived differentially with respect to the normal B star HD 137366 and indicate that PG 1610+062 is somewhat metal rich. A kinematic analysis, based on our spectrophotometric distance (17.3 kpc) and on proper motions from Gaia’s second data release, shows that PG 1610+062 was probably ejected from the Carina-Sagittarius spiral arm at a velocity of 550 ± 40 km s−1, which is beyond the classical limits. Accordingly, the star is in the top five of the most extreme MS disk runaway stars and is only the second among the five for which the chemical composition is known.
Astronomy and astrophysics : an international weekly journal
10.1051/0004-6361/201935429
1432-0746
wos:2019
L5
WOS:000479055300002
Irrgang, A (reprint author), Friedrich Alexander Univ Erlangen Nuremberg EAU, Dr Karl Remeis Observ, Astron Inst, Sternwartstr 7, D-96049 Bamberg, Germany.; Irrgang, A (reprint author), Friedrich Alexander Univ Erlangen Nuremberg EAU, ECAP, Astron Inst, Sternwartstr 7, D-96049 Bamberg, Germany., andreas.irrgang@fau.de
La Silla Paranal Observatory [091.C-0713(A)]; Alfred P. Sloan FoundationAlfred P. Sloan Foundation; U.S. Department of Energy Office of ScienceUnited States Department of Energy (DOE); Center for High-Performance Computing at the University of Utah; NASANational Aeronautics & Space Administration (NASA) [NAS5-98034]; National Aeronautics and Space AdministrationNational Aeronautics & Space Administration (NASA) [NNX08AR22G]; National Science FoundationNational Science Foundation (NSF) [AST-1238877]; National Aeronautics and Space AdministrationNational Aeronautics & Space Administration (NASA); National Science FoundationNational Science Foundation (NSF); W.M. Keck FoundationW.M. Keck Foundation; Brazilian Participation Group; Carnegie Institution for Science; Carnegie Mellon University; Chilean Participation Group; French Participation Group; Harvard-Smithsonian Center for AstrophysicsSmithsonian InstitutionHarvard-Smithsonian Center for Astrophysics; Instituto de Astrofisica de Canarias; Johns Hopkins UniversityJohns Hopkins University; Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo; Lawrence Berkeley National LaboratoryUnited States Department of Energy (DOE); Leibniz Institut fur Astrophysik Potsdam (AIP); Max-Planck-Institut fur Astronomie (MPIA Heidelberg); Max-Planck-Institut fur Astrophysik (MPA Garching); Max-Planck-Institut fur Extraterrestrische Physik (MPE); National Astronomical Observatories of China; New Mexico State University; New York University; University of Notre Dame; Observatorio Nacional/MCTI; Ohio State UniversityOhio State University; Pennsylvania State University; Shanghai Astronomical Observatory; United Kingdom Participation Group; Universidad Nacional Autonoma de MexicoUniversidad Nacional Autonoma de Mexico; University of Arizona; University of Colorado Boulder; University of Oxford; University of Portsmouth; University of Utah; University of Virginia; University of WashingtonUniversity of Washington; University of Wisconsin; Vanderbilt University; Yale University
2020-12-02T16:43:05+00:00
sword
importub
filename=package.tar
010a0fa004e31489bdff6e97b5a87eb5
false
true
Andreas Irrgang
Stephan Alfred Geier
Ulrich Heber
Thomas Kupfer
F. Fürst
eng
uncontrolled
stars: abundances
eng
uncontrolled
stars: individual: HD 137366
eng
uncontrolled
stars: kinematics and dynamics
eng
uncontrolled
stars: individual: PG 1610+062
eng
uncontrolled
stars: early-type
Physik
Institut für Physik und Astronomie
Referiert
Import
Bronze Open-Access
46640
2017
2017
eng
3105
3121
17
467
article
Oxford Univ. Press
Oxford
1
--
--
--
WR 148: identifying the companion of an extreme runaway massive binary
WR 148 (HD 197406) is an extreme runaway system considered to be a potential candidate for a short-period (4.3173 d) rare WR + compact object binary. Provided with new high-resolution, high signal-to-noise spectra from the Keck observatory, we determine the orbital parameters for both the primary WR and the secondary, yielding respective projected orbital velocity amplitudes of 88.1 ± 3.8 km s−1 and 79.2 ± 3.1 km s−1 and implying a mass ratio of 1.1 ± 0.1. We then apply the shift-and-add technique to disentangle the spectra and obtain spectra compatible with a WN7ha and an O4-6 star. Considering an orbital inclination of ∼67°, derived from previous polarimetry observations, the system's total mass would be a mere 2–3M⊙⁠, an unprecedented result for a putative massive binary system. However, a system comprising a 37M⊙ secondary (typical mass of an O5V star) and a 33M⊙ primary (given the mass ratio) would infer an inclination of ∼18°. We therefore reconsider the previous methods of deriving the orbital inclination based on time-dependent polarimetry and photometry. While the polarimetric results are inconclusive requiring better data, the photometric results favour low inclinations. Finally, we compute WR 148’s space velocity and retrace the runaway's trajectory back to the Galactic plane (GP). With an ejection velocity of 198 ± 27 km s−1 and a travel time of 4.7 ± 0.8 Myr to reach its current location, WR 148 was most likely ejected via dynamical interactions in a young cluster.
Monthly notices of the Royal Astronomical Society
10.1093/mnras/stw2283
0035-8711
1365-2966
wos:2017
WOS:000398419400047
Munoz, M; Moffat, AFJ (reprint author), Univ Montreal, Dept Phys, CP 6128,Succursale C-V, Montreal, PQ H3C 3J7, Canada.; Munoz, M; Moffat, AFJ (reprint author), Ctr Rech Astrophys Quebec, CP 6128,Succursale C-V, Montreal, PQ H3C 3J7, Canada.; Hill, GM (reprint author), WM Keck Observ, 65-1120 Mamalohoa, Kamuela, HI 96743 USA., munoz@astro.umontreal.ca; moffat@astro.umontreal.ca; ghill@keck.hawaii.edu
NSERC (Canada); FQRNT (Quebec); University of Toledo; Helen Luedtke Brooks Endowed Professorship; Canadian Space Agency grant FAST
importub
2020-04-20T03:09:01+00:00
filename=package.tar
8095aea2a35f56d05e76fff0487c5f4b
Melissa Munoz
Anthony F. J. Moffat
Grant M. Hill
Tomer Shenar
Noel D. Richardson
Herbert Pablo
Nicole St-Louis
Tahina Ramiaramanantsoa
eng
uncontrolled
binaries: spectroscopic
eng
uncontrolled
stars: individual: WR 148
eng
uncontrolled
stars: kinematics and dynamics
eng
uncontrolled
stars: mass-loss
eng
uncontrolled
stars: winds, outflows
eng
uncontrolled
stars: Wolf-Rayet
Institut für Physik und Astronomie
Referiert
Import
45467
2016
2016
eng
12
588
article
EDP Sciences
Les Ulis
1
--
--
--
MUSE crowded field 3D spectroscopy of over 12 000 stars in the globular cluster NGC 6397
We present a detailed analysis of the kinematics of the Galactic globular cluster NGC 6397 based on more than similar to 18 000 spectra obtained with the novel integral field spectrograph MUSE. While NGC 6397 is often considered a core collapse cluster, our analysis suggests a flattening of the surface brightness profile at the smallest radii. Although it is among the nearest globular clusters, the low velocity dispersion of NGC 6397 of < 5 km s(-1) imposes heavy demands on the quality of the kinematical data. We show that despite its limited spectral resolution, MUSE reaches an accuracy of 1 km s(-1) in the analysis of stellar spectra. We find slight evidence for a rotational component in the cluster and the velocity dispersion profile that we obtain shows a mild central cusp. To investigate the nature of this feature, we calculate spherical Jeans models and compare these models to our kinematical data. This comparison shows that if a constant mass-to-light ratio is assumed, the addition of an intermediate-mass black hole with a mass of 600 M-circle dot brings the model predictions into agreement with our data, and therefore could be at the origin of the velocity dispersion profile. We further investigate cases with varying mass-to-light ratios and find that a compact dark stellar component can also explain our observations. However, such a component would closely resemble the black hole from the constant mass-to-light ratio models as this component must be confined to the central similar to 5 ' of the cluster and must have a similar mass. Independent constraints on the distribution of stellar remnants in the cluster or kinematic measurements at the highest possible spatial resolution should be able to distinguish the two alternatives.
Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth
10.1051/0004-6361/201527065
1432-0746
wos2016:2019
A149
WOS:000373207800161
Kamann, S (reprint author), Univ Gottingen, Inst Astrophys, Friedrich Hund Pl 1, D-37077 Gottingen, Germany., skamann@astro.physik.uni-goettingen.de
BMBF Verbundforschung (project MUSE-AO) [05A14BAC, 05A14MGA]; DFG [SFB 963/1]
importub
2020-03-22T18:47:01+00:00
filename=package.tar
a892b97efef80098e936d9380aa41e3b
S. Kamann
T. -O. Husser
Jarle Brinchmann
E. Emsellem
Peter Michael Weilbacher
Lutz Wisotzki
Martin Wendt
D. Krajnovic
M. M. Roth
Roland Bacon
S. Dreizler
eng
uncontrolled
globular clusters: individual: NGC 6397
eng
uncontrolled
stars: kinematics and dynamics
eng
uncontrolled
techniques: radial velocities
eng
uncontrolled
techniques: imaging spectroscopy
eng
uncontrolled
black hole physics
Institut für Physik und Astronomie
Referiert
Import
37032
2011
2011
eng
147
152
6
2
332
article
Wiley-Blackwell
Malden
1
--
--
--
First detection of a magnetic field in the fast rotating runaway Oe star zeta Ophiuchi
The star zeta Ophiuchi is one of the brightest massive stars in the northern hemisphere and was intensively studied in various wavelength domains. The currently available observational material suggests that certain observed phenomena are related to the presence of a magnetic field. We acquired spectropolarimetric observations of zeta Oph with FORS 1 mounted on the 8-m Kueyen telescope of the VLT to investigate if a magnetic field is indeed present in this star. Using all available absorption lines, we detect a mean longitudinal magnetic field < B(z)>(all) = 141 +/- 45 G, confirming the magnetic nature of this star. We review the X-ray properties of zeta Oph with the aim to understand whether the X-ray emission of zeta Oph is dominated by magnetic or by wind instability processes.
Astronomische Nachrichten = Astronomical notes
10.1002/asna.201111516
0004-6337
wos:2011-2013
WOS:000287738000006
Hubrig, S (reprint author), Astrophys Inst Potsdam, Sternwarte 16, D-14482 Potsdam, Germany., shubrig@aip.de
NASA; [FKZ 50 OR 1101]
Swetlana Hubrig
Lida M. Oskinova
M. Schoeller
eng
uncontrolled
stars: mass-loss
eng
uncontrolled
stars: early-type
eng
uncontrolled
stars: magnetic field
eng
uncontrolled
stars: kinematics and dynamics
eng
uncontrolled
X-rays: stars
eng
uncontrolled
stars: individual: zeta Ophiuchi
Institut für Physik und Astronomie
Referiert
35176
2013
2013
eng
13
551
article
EDP Sciences
Les Ulis
MAGORI Collaboration
1
--
--
--
Exploring the origin of magnetic fields in massive stars - II. New magnetic field measurements in cluster and field stars
Context. Theories on the origin of magnetic fields in massive stars remain poorly developed, because the properties of their magnetic field as function of stellar parameters could not yet be investigated. Additional observations are of utmost importance to constrain the conditions that are conducive to magnetic fields and to determine first trends about their occurrence rate and field strength distribution.
Aims. To investigate whether magnetic fields in massive stars are ubiquitous or appear only in stars with a specific spectral classification, certain ages, or in a special environment, we acquired 67 new spectropolarimetric observations for 30 massive stars. Among the observed sample, roughly one third of the stars are probable members of clusters at different ages, whereas the remaining stars are field stars not known to belong to any cluster or association.
Methods. Spectropolarimetric observations were obtained during four different nights using the low-resolution spectropolarimetric mode of FOcal Reducer low dispersion Spectrograph (FORS 2) mounted on the 8-m Antu telescope of the VLT. Furthermore, we present a number of follow-up observations carried out with the high-resolution spectropolarimeters SOFIN mounted at the Nordic Optical Telescope (NOT) and HARPS mounted at the ESO 3.6 m between 2008 and 2011. To assess the membership in open clusters and associations, we used astrometric catalogues with the highest quality kinematic and photometric data currently available.
Results. The presence of a magnetic field is confirmed in nine stars previously observed with FORS 1/2: HD36879, HD47839, CPD-28 2561, CPD-47 2963, HD93843, HD148937, HD149757, HD328856, and HD164794. New magnetic field detections at a significance level of at least 3 sigma were achieved in five stars: HD92206c, HD93521, HD93632, CPD-46 8221, and HD157857. Among the stars with a detected magnetic field, five stars belong to open clusters with high membership probability. According to previous kinematic studies, five magnetic O-type stars in our sample are candidate runaway stars.
Astronomy and astrophysics : an international weekly journal
10.1051/0004-6361/201220721
0004-6361
wos:2011-2013
A33
WOS:000316460600033
Hubrig, S (reprint author), Leibniz Inst Astrophys Potsdam AIP, Sternwarte 16, D-14482 Potsdam, Germany., shubrig@aip.de
Deutsche Forschungsgemeinschaft [Hu532/17-1]
Swetlana Hubrig
M. Schoeller
Ilya Ilyin
N. V. Kharchenko
Lida M. Oskinova
N. Langer
J. F. Gonzalez
A. F. Kholtygin
Maryline Briquet
eng
uncontrolled
polarization
eng
uncontrolled
stars: early-type
eng
uncontrolled
stars: kinematics and dynamics
eng
uncontrolled
stars: magnetic field
eng
uncontrolled
stars: massive
eng
uncontrolled
open clusters and associations: general
Institut für Physik und Astronomie
Referiert