Search Publications
The lowest detected stellar Fe abundance: the halo star SMSS J160540.18-144323.1
Schmidt, B. P.; Da Costa, G. S.; Marino, A. F. +12 more
We report the discovery of SMSS J160540.18-144323.1, a new ultra metal-poor halo star discovered with the SkyMapper telescope. We measure [{Fe}/{H}]= -6.2 ± 0.2 (1D LTE), the lowest ever detected abundance of iron in a star. The star is strongly carbon-enhanced, [{C}/{Fe}] = 3.9 ± 0.2, while other abundances are compatible with an α-enhanced solar…
Multiphase circumgalactic medium probed with MUSE and ALMA
Pettini, Max; York, Donald G.; Hamanowicz, Aleksandra +9 more
Galaxy haloes appear to be missing a large fraction of their baryons, most probably hiding in the circumgalactic medium (CGM), a diffuse component within the dark matter halo that extends far from the inner regions of the galaxies. A powerful tool to study the CGM gas is offered by absorption lines in the spectra of background quasars. Here, we pr…
Common origin for Hercules-Aquila and Virgo Clouds in Gaia DR2
Belokurov, Vasily; Koposov, Sergey E.; Simion, Iulia T.
We use a sample of ∼350 RR Lyrae stars with radial velocities and Gaia Data Release 2 proper motions to study orbital properties of the Hercules-Aquila Cloud (HAC) and Virgo Over-density (VOD). We demonstrate that both structures are dominated by stars on highly eccentric orbits, with pericentres around ∼1 kpc and apocentres at 15-25 kpc from the …
The period-luminosity relation for δ Scuti stars using Gaia DR2 parallaxes
Bedding, Timothy R.; Murphy, Simon J.; Hey, Daniel R. +2 more
We have examined the period-luminosity (P-L) relation for δ Scuti stars using Gaia DR2 parallaxes. We included 228 stars from the catalogue of Rodríguez et al., as well as 1124 stars observed in the 4-yr Kepler mission. For each star, we considered the dominant pulsation period, and used DR2 parallaxes and extinction corrections to determine absol…
NGTS-4b: A sub-Neptune transiting in the desert
Jackman, James A. G.; Wheatley, Peter J.; Bayliss, Daniel +48 more
We report the discovery of NGTS-4b, a sub-Neptune-sized planet transiting a 13th magnitude K-dwarf in a 1.34 d orbit. NGTS-4b has a mass M = 20.6 ± 3.0 M⊕ and radius R = 3.18 ± 0.26 R⊕, which places it well within the so-called `Neptunian Desert'. The mean density of the planet (3.45 ± 0.95 g cm-3) is consistent wi…
Cosmological constraints on an exponential interaction in the dark sector
Yang, Weiqiang; Pan, Supriya; Paliathanasis, Andronikos
Cosmological models where dark matter (DM) and dark energy (DE) interact with each other are the general scenarios in compared to the non-interacting models. The interaction is usually motivated from the phenomenological ground and thus there is no such rule to prefer a particular interaction between DM and DE. Being motivated, in this work, allow…
A contribution of star-forming clumps and accreting satellites to the mass assembly of z ∼ 2 galaxies
Daddi, E.; Le Floc'h, E.; Bournaud, F. +14 more
We investigate the contribution of clumps and satellites to the galaxy mass assembly. We analysed spatially resolved HubbleSpace Telescope observations (imaging and slitless spectroscopy) of 53 star-forming galaxies at z ∼ 1-3. We created continuum and emission line maps and pinpointed residual `blobs' detected after subtracting the galaxy disc. T…
Early- and late-stage mergers among main sequence and starburst galaxies at 0.2 ≤ z ≤ 2
Daddi, E.; Elbaz, D.; Le Floc'h, E. +12 more
We investigate the fraction of close pairs and morphologically identified mergers on and above the star-forming main sequence (MS) at 0.2 ≤ z ≤2.0. The novelty of our work lies in the use of a non-parametric morphological classification performed on resolved stellar mass maps, reducing the contamination by non-interacting, high-redshift clumpy gal…
A volume-limited survey of mCP stars within 100 pc - I. Fundamental parameters and chemical abundances
Wade, G. A.; Neiner, C.; Sikora, J. +1 more
We present the first results of a volume-limited survey of main-sequence (MS) magnetic chemically peculiar (mCP) stars. The sample consists of all identified intermediate-mass MS stars (mCP and non-mCP) within a heliocentric distance of 100 pc as determined using Hipparcos parallaxes. The two populations are compared in order to determine the uniq…
Radial velocity confirmation of K2-100b: a young, highly irradiated, and low-density transiting hot Neptune
Tamura, M.; Aigrain, S.; Pagano, I. +37 more
We present a detailed analysis of HARPS-N radial velocity observations of K2-100, a young and active star in the Praesepe cluster, which hosts a transiting planet with a period of 1.7 d. We model the activity-induced radial velocity variations of the host star with a multidimensional Gaussian Process framework and detect a planetary signal of 10.6…