Search Publications
Characterisation of red supergiants in the Gaia spectral range
Negueruela, Ignacio; González-Fernández, Carlos; Dorda, Ricardo
Context. The infrared calcium triplet and its nearby spectral region have been used for spectral and luminosity classification of late-type stars, but the samples of cool supergiants (CSGs) used have been very limited (in size, metallicity range, and spectral types covered). The spectral range of the Gaia Radial Velocity Spectrograph (RVS) covers …
Hubble Space Telescope Snapshot Survey for Resolved Companions of Galactic Cepheids
Schaefer, Gail H.; Bond, Howard E.; Evans, Nancy Remage +4 more
We have conducted an imaging survey with the Hubble Space Telescope Wide Field Camera 3 (WFC3) of 70 Galactic Cepheids, typically within 1 kpc, with the aim of finding resolved physical companions. The WFC3 field typically covers the 0.1 pc area where companions are expected. In this paper, we identify 39 Cepheids having candidate companions, base…
Suprathermal Electrons at Saturn's Bow Shock
Coates, A. J.; Dougherty, M. K.; Fujimoto, M. +4 more
The leading explanation for the origin of galactic cosmic rays is particle acceleration at the shocks surrounding young supernova remnants (SNRs), although crucial aspects of the acceleration process are unclear. The similar collisionless plasma shocks frequently encountered by spacecraft in the solar wind are generally far weaker (lower Mach numb…
Deep Herschel PACS point spread functions
Abergel, A.; Bianchi, S.; Bocchio, M.
The knowledge of the point spread function (PSF) of imaging instruments represents a fundamental requirement for astronomical observations. The Herschel PACS PSFs delivered by the instrument control centre are obtained from observations of the Vesta asteroid, which provides a characterisation of the central part and, therefore, excludes fainter fe…
Scaling laws of coronal loops compared to a 3D MHD model of an active region
Peter, H.; Bingert, S.; Bourdin, Ph. -A.
Context. The structure and heating of coronal loops have been investigated for decades. Established scaling laws relate fundamental quantities like the loop apex temperature, pressure, length, and coronal heating.
Aims: We test these scaling laws against a large-scale 3D magneto-hydrodynamics (MHD) model of the solar corona, which became feas…
Collisional excitation of doubly and triply deuterated ammonia ND2H and ND3 by H2
Roueff, E.; Lis, D. C.; Daniel, F. +6 more
The availability of collisional rate coefficients is a prerequisite for an accurate interpretation of astrophysical observations, since the observed media often harbour densities where molecules are populated under non-local thermodynamic equilibrium conditions. In the current study, we present calculations of rate coefficients suitable to describ…
Direct search for features in the primordial bispectrum
Appleby, Stephen; Hazra, Dhiraj Kumar; Gong, Jinn-Ouk +2 more
We study features in the bispectrum of the primordial curvature perturbation correlated with the reconstructed primordial power spectrum from the observed cosmic microwave background temperature data. We first show how the bispectrum can be completely specified in terms of the power spectrum and its first two derivatives, valid for any configurati…
The Candidate Cluster and Protocluster Catalog (CCPC) of Spectroscopically Identified Structures Spanning 2.74 < z < 3.71
Franck, J. R.; McGaugh, S. S.
We developed a search methodology to identify galaxy protoclusters at z\gt 2.74 and implemented it on a sample of ∼14,000 galaxies with previously measured redshifts. The results of this search are recorded in the Candidate Cluster and Protocluster Catalog (CCPC). The catalog contains 12 clusters that are highly significant overdensities ({δ }
The Nucleus of the Planetary Nebula EGB 6 as a Post-Mira Binary
Bond, Howard E.; Munari, Ulisse; Ciardullo, Robin +3 more
EGB 6 is a faint, large, ancient planetary nebula (PN). Its central star, a hot DAOZ white dwarf (WD), is a prototype of a rare class of PN nuclei associated with dense, compact emission-line knots. The central star also shows excess fluxes in both the near-infrared (NIR) and mid-infrared (MIR). In a 2013 paper, we used Hubble Space Telescope (HST…
X-ray emission from the Wolf-Rayet bubble NGC 6888 - II. XMM-Newton EPIC observations
Gruendl, R. A.; Chu, Y. -H.; Guerrero, M. A. +3 more
We present deep XMM-Newton European Photon Imaging Camera observations of the Wolf-Rayet (WR) bubble NGC 6888 around the star WR 136. The complete X-ray mapping of the nebula confirms the distribution of the hot gas in three maxima spatially associated with the caps and north-west blowout hinted at by previous Chandra observations. The global X-ra…