Výsledky vyhledávání - "Dieter H. Nickeler"

Akademický článek

Rings, Shells, and Arc Structures Around B[e] Supergiants. I. Classical Tools of Nonlinear Hydrodynamics

Autor: Dieter H. Nickeler, Michaela Kraus

Publikováno v: The Astrophysical Journal, Vol 963, Iss 2, p 131 (2024)

Structures in circumstellar matter reflect both fast processes and quasi-equilibrium states. A geometrical diversity of emitting circumstellar matter is observed around evolved massive stars, in particular around B[e] supergiants. We recapitulate cla

Externí odkaz: https://doaj.org/article/973fe8cab0c9470182af20d95f5d6cad

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Akademický článek

Dense Molecular Environments of B[e] Supergiants and Yellow Hypergiants

Autor: Michaela Kraus, Michalis Kourniotis, María Laura Arias, Andrea F. Torres, Dieter H. Nickeler

Publikováno v: Galaxies, Vol 11, Iss 3, p 76 (2023)

Massive stars expel large amounts of mass during their late evolutionary phases. We aim to unveil the physical conditions within the warm molecular environments of B[e] supergiants (B[e]SGs) and yellow hypergiants (YHGs), which are known to be embedd

Externí odkaz: https://doaj.org/article/dec091d0e4e74470b0a4093f95551293

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Resolving the circumstellar environment of the Galactic B[e] supergiant star MWC 137, II : nebular kinematics and stellar variability

Autor: Alexei Moiseev, David O. Jones, Dieter H. Nickeler, Julieta Paz Sánchez Arias, Lydia Sonia Cidale, T. Liimets, Michaela Kraus

Publikováno v: CONICET Digital (CONICET)
Consejo Nacional de Investigaciones Científicas y Técnicas
instacron:CONICET
The Astronomical Journal

The Galactic B[e] supergiant MWC 137 is surrounded by a large-scale optical nebula. To shed light on the physical conditions and kinematics of the nebula, we analyze the optical forbidden emission lines [NII] 6548,6583 and [SII] 6716,6731 in long-sli

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::50ded3c1d8e2a5ebe95f41b0a1079ad0

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Topological structures of velocity and electric field in the vicinity of a cusp-type magnetic null point

Autor: Michaela Kraus, Marian Karlický, Dieter H. Nickeler

Topological characteristics reveal important physical properties of plasma structures and astrophysical processes. Physical parameters and constraints are linked with topological invariants, which are important for describing magnetic reconnection sc

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::7487746a01db155d864ff7c7b115b14c

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Electric current filamentation induced by 3D plasma flows in the solar corona

Autor: Thomas Wiegelmann, Michaela Kraus, Marian Karlický, Dieter H. Nickeler

Many magnetic structures in the solar atmosphere evolve rather slowly so that they can be assumed as (quasi-)static or (quasi-)stationary and represented via magneto-hydrostatic (MHS) or stationary magneto-hydrodynamic (MHD) equilibria, respectively.

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::73527c6356e3784cb02a64ec32f4a9a1

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Inhomogeneous molecular ring around the B[e] supergiant LHA 120-S 73

Autor: Grigoris Maravelias, Michel Curé, M. Borges Fernandes, R. Vallverdú, Rodolfo H. Barbá, M. L. Arias, Dieter H. Nickeler, Manfred Kraus, Lydia Sonia Cidale, Anna Aret, Andrea Fabiana Torres

Publikováno v: SEDICI (UNLP)
Universidad Nacional de La Plata
instacron:UNLP
CONICET Digital (CONICET)
Consejo Nacional de Investigaciones Científicas y Técnicas
instacron:CONICET

Context. B[e] supergiants are evolved massive stars, enshrouded in a dense wind and surrounded by a molecular and dusty disk. The mechanisms that drive phases of enhanced mass loss and mass ejections, responsible for the shaping of the circumstellar

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c0e321630513ddf9409dcabd60a4624f

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Are heliospheric flows magnetic line- or flux-conserving?

Autor: Dieter H. Nickeler, Marian Karlický

Publikováno v: Astrophysics and Space Sciences Transactions. 2:63-72

This article discusses and tests the validity of the frozen in magnetic field paradigm (or 'ideal magnetohydro- dynamics (MHD) constraint') which is usually adopted by many authors dealing with heliospheric physics. To show the problem of using ideal

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::ce87c27b5d33466d7ac86335497e7c2a
https://doi.org/10.5194/astra-2-63-2006

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Resolving the Circumstellar Environment of the Galactic B[e] Supergiant Star MWC 137 from Large to Small Scales

Autor: Grigoris Maravelias, Dieter H. Nickeler, D. S. Gunawan, Michel Curé, Cristina Elisabet Cappa, N. U. Duronea, T. Liimets, Miguel Santander-García, Mary E. Oksala, M. L. Arias, Lydia Sonia Cidale, Michaela Kraus, Marcelo Borges Fernandes

Publikováno v: SEDICI (UNLP)
Universidad Nacional de La Plata
instacron:UNLP
CONICET Digital (CONICET)
Consejo Nacional de Investigaciones Científicas y Técnicas
instacron:CONICET
The Astronomical Journal
The Astronomical Journal, American Astronomical Society, 2017, 154 (5), pp.186. ⟨10.3847/1538-3881/aa8df6⟩
The Astronomical Journal, 2017, 154 (5), pp.186. ⟨10.3847/1538-3881/aa8df6⟩

The Galactic object MWC 137 has been suggested to belong to the group of B[e] supergiants. However, with its large-scale optical bipolar ring nebula and high-velocity jet and knots, it is a rather atypical representative of this class. We performed m

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::572f0cafbebe6556cb8dbf99418c3e7c
https://doi.org/10.3847/1538-3881/aa8df6

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Pulsations as a mass-loss trigger in evolved hot stars

Autor: Dieter H. Nickeler, Michel Curé, Marcelo Borges Fernandes, S. Tomic, Lydia Sonia Cidale, Michaela Kraus, R. O. J. Venero, M. Haucke

During the post-main sequence evolution massive stars pass through several short-lived phases, in which they experience enhanced mass loss in the form of clumped winds and mass ejection events of unclear origin. The discovery that stars populating th

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::e24c7110c1a6b1baabca3529d81a4c23
http://arxiv.org/abs/1309.4904

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Fragmentation of electric currents in the solar corona by plasma flows

Autor: Dieter H. Nickeler, Michaela Kraus, Thomas Wiegelmann, Marian Karlicky

Publikováno v: Astronomy & Astrophysics. 556:A61

We consider a magnetic configuration consisting of an arcade structure and a detached plasmoid, resulting from a magnetic reconnection process, as is typically found in connection with solar flares. We study spontaneous current fragmentation caused b

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::1da5320812eab56413f0744750db43ca
https://doi.org/10.1051/0004-6361/201321847

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