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Mixed inflaton and spectator field models after Planck
Takahashi, Tomo; Enqvist, Kari
We investigate the possibility that the primordial perturbation has two sources: the inflaton and a spectator field, which is not dynamically important during inflation but which after inflation can contribute to the curvature perturbation. We derive the constraints on the model by using recent Planck results on the spectral index, tensor-to-scala…
Gas-phase CO depletion and N2H+ abundances in starless cores
Henning, Th.; Krause, O.; Balog, Z. +10 more
Context. In the dense and cold interiors of starless molecular cloud cores, a number of chemical processes allow for the formation of complex molecules and the deposition of ice layers on dust grains. Dust density and temperature maps of starless cores derived from Herschel continuum observations constrain the physical structure of the cloud cores…
Energetic neutral atom imaging of the lunar surface
Barabash, S.; Holmström, M.; Futaana, Y. +7 more
Since the Moon is not shielded by a global magnetic field or by an atmosphere, solar wind plasma impinges onto the lunar surface almost unhindered. Until recently, it was assumed that almost all of the impinging solar wind ions are absorbed by the surface. However, recent Interstellar Boundary Explorer, Chandrayaan-1, and Kaguya observations showe…
Hemispheric asymmetries of the Venus plasma environment
Kallio, E.; Jarvinen, R.; Dyadechkin, S.
We study the Venus-solar wind interaction and the hemispheric asymmetries of the Venus plasma environment in the global HYB-Venus hybrid simulation. We concentrate especially on the role of the flow-aligned interplanetary magnetic field (IMF) component (i.e., the Parker spiral angle or the IMF cone angle) and analyze the dawn-dusk and Esw
A detailed X-ray investigation of ζ Puppis. III. Spectral analysis of the whole RGS spectrum
Nazé, Y.; Rauw, G.; Hervé, A.
Context. ζ Pup is the X-ray brightest O-type star of the sky. This object was regularly observed with the RGS instrument onboard XMM-Newton for calibration purposes, which led to an unprecedented set of high-quality spectra.
Aims: We have previously reduced and extracted this data set and integrated it into the most detailed high-resolution X…
Mars impact ejecta in the regolith of Phobos: Bulk concentration and distribution
Head, James W.; Ramsley, Kenneth R.
The gravity of Mars and the observation of a thick Phobos regolith suggest that nearly all Phobos ejecta returns to Phobos and re-impacts on Phobos. Primary ejecta from Mars typically impacts Phobos at velocities of ~2-3 km/s and due to the low escape velocity from Phobos of ~4-10 m/s, ~95-99% of the secondary ejecta from Phobos is inserted into t…
The Distance to the Massive Galactic Cluster Westerlund 2 from a Spectroscopic and HST Photometric Study
Kobulnicky, Henry A.; Vargas Álvarez, Carlos A.; Bradley, David R. +4 more
We present a spectroscopic and photometric determination of the distance to the young Galactic open cluster Westerlund 2 using WFPC2 imaging from the Hubble Space Telescope (HST) and ground-based optical spectroscopy. HST imaging in the F336W, F439W, F555W, and F814W filters resolved many sources previously undetected in ground-based observations …
Full halo coronal mass ejections: Do we need to correct the projection effect in terms of velocity?
Wang, Yuming; Shen, Chenglong; Wang, S. +3 more
The projection effect is one of the biggest obstacles in learning the real properties of coronal mass ejections (CMEs) and forecasting their geoeffectiveness. To evaluate the projection effect, 86 full halo CMEs (FHCMEs) listed in the Coordinated Data Analysis Workshop CME catalog from 1 March 2007 to 31 May 2012 are investigated. By applying the …
Variable Stars in the Globular Cluster NGC 2808
Kunder, Andrea; Walker, Alistair R.; Stetson, Peter B. +2 more
The first calibrated broadband BVI time-series photometry is presented for the variable stars in NGC 2808, with observations spanning a range of 28 years. We have also redetermined the variability types and periods for the variable stars identified previously by Corwin et al., revising the number of probable fundamental-mode RR Lyrae variables (RR…
RX J1301.9+2747: A Highly Variable Seyfert Galaxy with Extremely Soft X-Ray Emission
Shu, Xinwen; Wang, Tinggui; Sun, Luming
In this paper we present a temporal and spectral analysis of X-ray data from XMM-Newton and Chandra observations of the ultrasoft and variable Seyfert galaxy RX J1301.9+2747. In both observations the source clearly displays two distinct states in the X-ray band: a long quiescent state and a short flare (or eruptive) state which differs in count ra…