Search Publications
Chemo-dynamics of outer halo dwarf stars, including Gaia-Sausage and Gaia-Sequoia candidates
Monty, Stephanie; Venn, Kim A.; Lane, James M. M. +2 more
The low-metallicity, kinematically interesting dwarf stars studied by Stephens & Boesgaard (2002, SB02) are re-examined using Gaia DR2 astrometry, and updated model atmospheres and atomic line data. New stellar parameters are determined based on the Gaia DR2 parallactic distances and Dartmouth Stellar Evolution Database isochrones. These are i…
Elevated ionizing photon production efficiency in faint high-equivalent-width Lyman-α emitters
Bacon, Roland; Inami, Hanae; Brinchmann, Jarle +16 more
While low-luminosity galaxies dominate number counts at all redshifts, their contribution to cosmic reionization is poorly understood due to a lack of knowledge of their physical properties. We isolate a sample of 35 z ≈ 4-5 continuum-faint Lyman-α emitters from deep VLT/MUSE spectroscopy and directly measure their H α emission using stacked Spitz…
Is multiphase gas cloudy or misty?
Gronke, Max; Oh, S. Peng
Cold T ∼ 104 K gas morphology could span a spectrum ranging from large discrete clouds to a fine 'mist' in a hot medium. This has myriad implications, including dynamics and survival, radiative transfer, and resolution requirements for cosmological simulations. Here, we use 3D hydrodynamic simulations to study the pressure-driven fragme…
The first six months of the Advanced LIGO's and Advanced Virgo's third observing run with GRANDMA
Bertin, E.; Kann, D. A.; Berthier, J. +74 more
We present the Global Rapid Advanced Network Devoted to the Multi-messenger Addicts (GRANDMA). The network consists of 21 telescopes with both photometric and spectroscopic facilities. They are connected together thanks to a dedicated infrastructure. The network aims at coordinating the observations of large sky position estimates of transient eve…
Unlocking Galactic Wolf-Rayet stars with Gaia DR2 - I. Distances and absolute magnitudes
Crowther, Paul A.; Rate, Gemma
We obtain distances to 383 Galactic Wolf-Rayet (WR) stars from Gaia DR2 parallaxes and Bayesian methods, with a prior based on H II regions and dust extinction. Distances agree with those from Bailer-Jones et al. for stars up to 2 kpc from the Sun, though deviate thereafter due to differing priors, leading to modest reductions in luminosities for …
Interpreting the Spitzer/IRAC colours of 7 ≤ z ≤ 9 galaxies: distinguishing between line emission and starlight using ALMA
Laporte, N.; Ellis, R. S.; Roberts-Borsani, G. W.
Prior to the launch of JWST, Spitzer/IRAC photometry offers the only means of studying the rest-frame optical properties of z >7 galaxies. Many such high-redshift galaxies display a red [3.6]-[4.5] micron colour, often referred to as the 'IRAC excess', which has conventionally been interpreted as arising from intense [O III]+H β emission within…
Star cluster formation in the most extreme environments: insights from the HiPEEC survey
Östlin, G.; Larsen, S. S.; Sabbi, E. +14 more
We present the Hubble imaging Probe of Extreme Environments and Clusters (HiPEEC) survey. We fit HST NUV to NIR broad-band and H α fluxes to derive star cluster ages, masses, and extinctions and determine the star formation rate (SFR) of six merging galaxies. These systems are excellent laboratories to trace cluster formation under extreme gas phy…
How comets work: nucleus erosion versus dehydration
Blum, J.; Güttler, C.; Gundlach, B. +3 more
We develop an activity model based on ice sublimation and gas diffusion inside cm-sized pebbles making-up a cometary nucleus. Our model explains cometary activity assuming no free parameters and fixing the nucleus surface temperature Ts, its gradient below the nucleus surface at thermal equilibrium, the pressure inside the porous pebble…
Nebular spectra of 111 Type Ia supernovae disfavour single-degenerate progenitors
Kochanek, C. S.; Galbany, L.; Kumar, S. +15 more
We place statistical constraints on Type Ia supernova (SN Ia) progenitors using 227 nebular-phase spectra of 111 SNe Ia. We find no evidence of stripped companion emission in any of the nebular-phase spectra. Upper limits are placed on the amount of mass that could go undetected in each spectrum using recent hydrodynamic simulations. With these nu…
Completeness of the Gaia verse II: what are the odds that a star is missing from Gaia DR2?
Everall, Andrew; Boubert, Douglas
The second data release of the Gaia mission contained astrometry and photometry for an incredible 1692 919 135 sources, but how many sources did Gaiamiss and where do they lie on the sky? The answer to this question will be crucial for any astronomer attempting to map the Milky Way with Gaia DR2. We infer the completeness of Gaia DR2 by exploiting…