Search Publications
Constraining neutrino mass and extra relativistic degrees of freedom in dynamical dark energy models using Planck 2015 data in combination with low-redshift cosmological probes: basic extensions to ΛCDM cosmology
Zhang, Jing-Fei; Zhang, Xin; Li, Yun-He +1 more
We investigate how the properties of dark energy affect the cosmological measurements of neutrino mass and extra relativistic degrees of freedom. We limit ourselves to the most basic extensions of Λ cold dark matter (CDM) model, I.e. the wCDM model with one additional parameter w, and the w0waCDM model with two additional par…
Hertzsprung-Russell diagram and mass distribution of barium stars
Jorissen, A.; Pourbaix, D.; Escorza, A. +6 more
With the availability of parallaxes provided by the Tycho-Gaia Astrometric Solution, it is possible to construct the Hertzsprung-Russell diagram (HRD) of barium and related stars with unprecedented accuracy. A direct result from the derived HRD is that subgiant CH stars occupy the same region as barium dwarfs, contrary to what their designations i…
A Comet Active Beyond the Crystallization Zone
Mutchler, Max; Jewitt, David; Agarwal, Jessica +3 more
We present observations showing inbound long-period comet C/2017 K2 (PANSTARRS) to be active at a record heliocentric distance. Nucleus temperatures are too low (60-70 K) either for water ice to sublimate or for amorphous ice to crystallize, requiring another source for the observed activity. Using the Hubble Space Telescope we find a sharply boun…
Hybrid modelling of cometary plasma environments. I. Impact of photoionisation, charge exchange, and electron ionisation on bow shock and cometopause at 67P/Churyumov-Gerasimenko
Kallio, E.; Gunell, H.; Behar, E. +7 more
Context. The ESA/Rosetta mission made it possible to monitor the plasma environment of a comet, from near aphelion to perihelion conditions. To understand the complex dynamics and plasma structures found at the comet, a modelling effort must be carried out in parallel.
Aims: Firstly, we present a 3D hybrid model of the cometary plasma environ…
Astrochemical Properties of Planck Cold Clumps
Sanhueza, Patricio; Choi, Minho; Di Francesco, James +26 more
We observed 13 Planck cold clumps with the James Clerk Maxwell Telescope/SCUBA-2 and with the Nobeyama 45 m radio telescope. The N2H+ distribution obtained with the Nobeyama telescope is quite similar to SCUBA-2 dust distribution. The 82 GHz HC3N, 82 GHz CCS, and 94 GHz CCS emission are often distributed differentl…
A Parameter Study for Modeling Mg II h and k Emission during Solar Flares
Kleint, Lucia; Rubio da Costa, Fatima
Solar flares show highly unusual spectra in which the thermodynamic conditions of the solar atmosphere are encoded. Current models are unable to fully reproduce the spectroscopic flare observations, especially the single-peaked spectral profiles of the Mg II h and k lines. We aim to understand the formation of the chromospheric and optically thick…
HST Imaging of the Brightest z ∼ 8-9 Galaxies from UltraVISTA: The Extreme Bright End of the UV Luminosity Function
Holwerda, Benne W.; Franx, Marijn; Illingworth, Garth D. +13 more
We report on the discovery of three especially bright candidate {z}{phot}≳ 8 galaxies. Five sources were targeted for follow-up with the Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3), selected from a larger sample of 16 bright (24.8≲ H≲ 25.5 mag) candidate z≳ 8 Lyman break galaxies (LBGs) identified over 1.6 degrees2
UVI colour gradients of 0.4 < z < 1.4 star-forming main-sequence galaxies in CANDELS: dust extinction and star formation profiles
Kocevski, Dale D.; Koekemoer, Anton M.; Pacifici, Camilla +10 more
This paper uses radial colour profiles to infer the distributions of dust, gas and star formation in z = 0.4-1.4 star-forming main-sequence galaxies. We start with the standard UVJ-based method to estimate dust extinction and specific star formation rate (sSFR). By replacing J with I band, a new calibration method suitable for use with ACS+WFC3 da…
MUSE deep-fields: the Ly α luminosity function in the Hubble Deep Field-South at 2.91 < z < 6.64
Bacon, Roland; Blaizot, Jérémy; Garel, Thibault +14 more
We present the first estimate of the Ly α luminosity function using blind spectroscopy from the Multi Unit Spectroscopic Explorer, MUSE, in the Hubble Deep Field-South. Using automatic source-detection software, we assemble a homogeneously detected sample of 59 Ly α emitters covering a flux range of -18.0 < log10 (F) < -16.3 (erg …
Discovery of a variable lead-rich hot subdwarf: UVO 0825+15
Reed, M. D.; Jeffery, C. S.; Woolf, V. M. +8 more
UVO 0825+15 is a hot bright helium-rich subdwarf which lies in K2 Field 5 and in a sample of intermediate helium-rich subdwarfs observed the Subaru High Dispersion Spectrograph. The K2 light curve shows low-amplitude variations, whilst the Subaru spectrum shows Pb IV absorption lines, indicative of a very high lead overabundance. UVO 0825+15 also …