| 1. |
- Kehoe, Laura, et al.
(författare)
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Make EU trade with Brazil sustainable
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
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| 3. |
- Fensch, Jeremy, et al.
(författare)
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Massive star cluster formation and evolution in tidal dwarf galaxies
- 2019
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The formation of globular clusters remains an open debate. Dwarf starburst galaxies are efficient at forming young massiveclusters with similar masses as globular clusters and may hold the key to understanding their formation.Aims.We study star cluster formation in a tidal debris - including the vicinity of three tidal dwarf galaxies - in a massive gas dominatedcollisional ring around NGC 5291. These dwarfs have physical parameters which differ significantly from local starbursting dwarfs.They are gas-rich, highly turbulent, have a gas metallicity already enriched up to half-solar, and are expected to be free of dark matter.The aim is to study massive star cluster formation in this as yet unexplored type of environment.Methods.We use imaging from theHubble Space Telescopeusing broadband filters covering the wavelength range from the near-ultraviolet to the near-infrared. We determine the masses and ages of the cluster candidates by using the spectral energy distribution-fitting code CIGALE, carefully considering age-extinction degeneracy effects on the estimation of the physical parameters.Results.We find that the tidal dwarf galaxies in the ring of NGC 5291 are forming star clusters with an average efficiency of∼40%,comparable to blue compact dwarf galaxies. We also find massive star clusters for which the photometry suggests that they wereformed at the very birth of the tidal dwarf galaxies and have survived for several hundred million years. Therefore our study showsthat extended tidal dwarf galaxies and compact clusters may be formed simultaneously. In the specific case observed here, the youngstar clusters are not massive enough to survive for a Hubble time. However one may speculate that similar objects at higher redshift,with higher star formation rate, might form some of the long lived globular clusters.Key words.galaxies: dwarf, galaxies: star clusters: general, galaxies: irregular, galaxies: star formation, galaxies: stellar content,galaxies: interactions
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| 4. |
- Odelstad, Elias, et al.
(författare)
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Plasma density and magnetic field fluctuations in the ion gyro-frequency range near the diamagnetic cavity of comet 67P
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We report the detection of large-amplitude, quasi-harmonic density-fluctuations with associated magnetic field oscillations in the region surrounding the diamagnetic cavity of comet 67P. Typical frequencies are ~0.1 Hz, corresponding to ~10 times the water and <0.5 times the proton gyro-frequencies, respectively. Magnetic field oscillations are not always clearly observed in association to these density fluctuations, but when they are, they consistently have wave vectors perpendicular to the background magnetic field, with the principal axis of polarization close to field-aligned and with a ~90° phase lag w.r.t. the density fluctuations. The fluctuations are observed in association with asymmetric plasma and magnetic field enhancements previously found in the region surrounding the diamagnetic cavity, occurring predominantly on their descending slopes. We speculate that they are Ion Bernstein waves (IBWs) excited by the drift-cyclotron instability resulting from strong plasma inhomogeneities in the region surrounding the diamagnetic cavity.
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| 5. |
- Odelstad, Elias, et al.
(författare)
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Plasma density and magnetic field fluctuations in the ion gyro-frequency range near the diamagnetic cavity of comet 67P
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We report the detection of large-amplitude, quasi-harmonic density-fluctuations with associated magnetic field oscillations in the region surrounding the diamagnetic cavity of comet 67P. Typical frequencies are ~0.1 Hz, corresponding to ~10 times the water and <0.5 times the proton gyro-frequencies, respectively. Magnetic field oscillations are not always clearly observed in association to these density fluctuations, but when they are, they consistently have wave vectors perpendicular to the background magnetic field, with the principal axis of polarization close to field-aligned and with a ~90° phase lag w.r.t. the density fluctuations. The fluctuations are observed in association with asymmetric plasma and magnetic field enhancements previously found in the region surrounding the diamagnetic cavity, occurring predominantly on their descending slopes. We speculate that they are Ion Bernstein waves (IBWs) excited by the drift-cyclotron instability resulting from strong plasma inhomogeneities in the region surrounding the diamagnetic cavity.
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