Browsing University of Hertfordshire by Title
Now showing items 3885-3904 of 24120
-
Constraining cosmic scatter in the Galactic halo through a differential analysis of metal-poor stars
(2017-12)Context. The chemical abundances of metal-poor halo stars are important to understanding key aspects of Galactic formation and evolution. Aims. We aim to constrain Galactic chemical evolution with precise chemical abundances ... -
Constraining Nucleosynthesis in Two CEMP Progenitors Using Fluorine
(2020-11-01)We present new fluorine abundance estimations in two carbon enhanced metal-poor (CEMP) stars, HE 1429-0551 and HE 1305+0007. HE 1429-0551 is also enriched in slow neutron-capture process (s-process) elements, a CEMP-s, and ... -
Constraining stellar assembly and active galactic nucleus feedback at the peak epoch of star formation
(2012-09-01)We study stellar assembly and feedback from active galactic nuclei (AGN) around the epoch of peak star formation (1 ≲ z ≲ 2), by comparing hydrodynamic simulations to rest-frame UV-optical galaxy colours from the Wide Field ... -
Constraining the astrophysical origin of the p-nuclei through nuclear physics and meteoritic data
(2013-06-01)A small number of naturally occurring, proton-rich nuclides (the p-nuclei) cannot be made in the s- and r-processes. Their origin is not well understood. Massive stars can produce p-nuclei through photodisintegration of ... -
Constraining the difference in convective blueshift between the components of alpha Centauri with precise radial velocities
(2002-04)New radial velocities of Cen A & B obtained in the framework the Anglo-Australian Planet Search programme as well as in the CORALIE programme are added to those by Endl et al. (2001) to improve the precision of the orbital ... -
A Constraint Satisfaction Method for Configuring Non-Local Service Interfaces
(Springer Nature, 2016-05-24)Modularity and decontextualization are core principles of a service-oriented architecture. However, the principles are often lost when it comes to an implementation of services due to rigid service interfaces. This paper ... -
Constraints on massive star formation : Cygnus OB2 was always an association
(2014-02-01)We examine substructure and mass segregation in the massive OB association Cygnus OB2 to better understand its initial conditions. Using a well-understood Chandra X-ray selected sample of young stars, we find that Cyg OB2 ... -
Constraints on photoevaporation models from (lack of) radio emission in the Corona Australis protoplanetary disks
(2014-10-21)Photoevaporation due to high-energy stellar photons is thought to be one of the main drivers of protoplanetary disk dispersal. The fully or partially ionized disk surface is expected to produce free-free continuum emission ... -
Constraints on positron annihilation kinematics in the inner Galaxy
(2019-07-01)Context. The annihilation of cosmic positrons with electrons in the interstellar medium results in the strongest persistent γ-ray line signal in the sky. For the past 50 yr, this 511 keV emission - predominantly from the ... -
Constraints on rotational mixing from surface evolution of light elements in massive stars
(2010-11)Context. Light elements and nitrogen surface abundances together can constrain the mixing efficiencies in massive stars on the main sequence, because moderate mixing in the surface layers leads to depletion of light elements ... -
Constraints on star-forming galaxies at z≥ 6.5 from HAWK-I Y-band imaging of GOODS-South
(2010)We present the results of our search for high-redshift Lyman-break galaxies over the GOODS-South field. We use Hubble Space Telescope (HST)-ACS data in B, V, i' & z', Very Large Telescope (VLT)-ISAAC J and Ks, Spitzer–Infrared ... -
Constraints on the circumstellar dust around KIC 8462852
(2016-05-01)We present millimetre (SMA) and sub-millimetre (SCUBA-2) continuum observations of the peculiar star KIC 8462852 which displayed several deep and aperiodic dips in brightness during the Kepler mission. Our observations are ... -
Constraints on the formation of the galactic bulge from Na, Al, and heavy-element abundances in Plaut's field.
(2012-04-05)We report chemical abundances of Na, Al, Zr, La, Nd, and Eu for 39 red giant branch (RGB) stars and 23 potential inner disk red clump stars located in Plaut's low-extinction window. We also measure lithium for a super ... -
Constraints on the nearby exoplanet Eps Ind Ab from deep near/mid-infrared imaging limits
(2021-07-21)The past decade has seen increasing efforts in detecting and characterising exoplanets by high contrast imaging in the near/mid-infrared, which is the optimal wavelength domain for studying old, cold planets. In this work, ... -
Constraints on the nuclear emission of the Circinus galaxy : optical and near-IR spectropolarimetry
(2000)We present optical and, for the first time, K-band spectropolarimetry of the nuclear region of the Circinus galaxy. In the optical we confirm the previous discovery of polarized broad Hα. We have not detected polarized ... -
Constraints on the ubiquity of coronal X-ray cycles
(2012-11-10)Stellar activity cycles are known to be a widespread phenomenon amongst moderately active solar- and late-type stars from long-term periodic variations in chromospheric Ca II H and K emission lines, yet to date, only a ...