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Evidence of the nonstationarity of the terrestrial bow shock from multi-spacecraft observations: methodology, results, and quantitative comparison with particle-in-cell (PIC) simulations
Mazelle, Christian; Lembège, Bertrand
The nonstationarity of the terrestrial bow shock is analyzed in detail from in situ magnetic field measurements issued from the fluxgate magnetometer (FGM) experiment of the Cluster mission. Attention is focused on statistical analysis of quasi-perpendicular supercritical shock crossings. The present analysis stresses for the first time the import…
Rotational excitation of highly excited H2O by H2
Żóltowski, Michal; Lique, François; Karska, Agata +1 more
Water is a key molecule for interstellar chemistry. Observations with Herschel telescope show significant population of very high rotational transitions (j ≳ 8) in young stellar objects, indicating significant amounts of water in hot (T ≳ 1500 K) and dense (n ≳ 106 cm-3) gas. Non-local thermodynamic equilibrium (LTE) modellin…
High-resolution CARMA Observation of Molecular Gas in the North America and Pelican Nebulae
Mairs, Steve; Nakamura, Fumitaka; Klessen, Ralf S. +15 more
In this paper, we present the first results from a CARMA high-resolution 12CO(1-0), 13CO(1-0), and C18O(1-0) molecular line survey of the North America and Pelican (NAP) Nebulae. CARMA observations have been combined with single-dish data from the Purple Mountain 13.7 m telescope, to add short spacings and to produ…
K2, Spitzer, and TESS Transits of Four Sub-Neptune Exoplanets
Deming, Drake; Crossfield, Ian; Harada, Caleb K. +5 more
We present new Spitzer transit observations of four K2 transiting sub-Neptunes: K2-36 c, K2-79b, K2-167b, and K2-212b. We derive updated orbital ephemerides and radii for these planets based on a joint analysis of the Spitzer, TESS, and K2 photometry. We use the EVEREST pipeline to provide improved K2 photometry, by detrending instrumental noise a…
Orbital eccentricities as indicators of stellar populations. A kinematical analysis of the local disc from Gaia DR2 catalogue
Cubarsi, R.; Stojanović, M.; Ninković, S.
Aims: Based on a local sample from Gaia DR2 catalogue composed of 74 339 stars, we are able to derive more accurate kinematic statistics defining the local stellar populations and classify the stars in terms of their planar and vertical orbital eccentricities.
Methods: Firstly, we carried out a kinematical characterisation of stellar pop…
Optical counterparts of ULXs in two dwarf galaxies: NGC 4861 and NGC 4449
Ozdogan Ela, M.; Akyuz, A.; Aksaker, N. +7 more
We present the results of a search for optical candidates of ultraluminous X-ray sources (ULXs) in two dwarf galaxies, NGC 4861 and NGC 4449, using Hubble Space Telescope (HST) archival data. With precise astrometry, we confirm that NGC 4861 X1 is associated with an H II complex and we conclude that NGC 4861 X2 resides in a young star group of mas…
The destruction of the cometary nucleus - The case of 73P/Schwassmann-Wachmann
Wesołowski, M.
The paper presents an analysis of the actual brightness change of comet 73P/Schwassmann-Wachmann, which took place in 1995. The consequence of a cometary outburst is the destruction of a fragment of its surface. This causes the emission of comet material from both the surface and from exposed subsurface layers. Therefore, the calculations take int…
Partitioning the Galactic halo with Gaussian Mixture Models
Zhao, Gang; Zhao, Jing-Kun; Liang, Xi-Long +1 more
The Galactic halo is supposed to form from merging with nearby dwarf galaxies. In order to probe different components of the Galactic halo, we have applied the Gaussian Mixture Models method to a selected sample of metal poor stars with [Fe/H] < -0.7 dex in the APOGEE DR16 catalogue based on four-parameters, metallicity, [Mg/Fe] ratio and spati…
Evidence for Cold Plasma in Planetary Nebulae From Radio Observations With the LOw Frequency ARray (LOFAR)
White, Glenn J.; Haverkorn, Marijke; Shimwell, Timothy +6 more
We present observations of planetary nebulae with the LOw Frequency ARray (LOFAR) between 120 and 168 MHz. The images show thermal free-free emission from the nebular shells. We have determined the electron temperatures for spatially resolved, optically thick nebulae. These temperatures are 20%-60% lower than those estimated from collisionally exc…
On the unified view of extragalactic sources based on their broadband emission properties
Iyida, E. U.; Eya, I. O.; Odo, F. C.
Our understanding of the unification of jetted active galactic nuclei (AGNs) has advanced greatly as the size of extragalactic sources increased. In this paper, based on the large sample of radio sources, we compiled 680 blazars (279 flat spectrum radio quasars (FSRQs) and 401 BL Lacertae (BL Lacs)) from the 3FGL sample and 64 Seyfert galaxies (3 …