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The deep OB star population in Carina from the VST Photometric Hα Survey (VPHAS+)

Massive OB stars are critical to the ecology of galaxies and yet our knowledge of OB stars in the Milky Way, fainter than V ∼ 12, remains patchy. Data from the VST Photometric Hα Survey (VPHAS+) permit the construction of the first deep catalogues of blue excess-selected OB stars, without neglecting the stellar field. A total of 14 900 candidates with 2MASS cross-matches are ...

Universe opacity and EBL

The observed extragalactic background light (EBL) is affected by light attenuation due to absorption of light by galactic and intergalactic dust in the Universe. Even galactic opacity of 10–20 per cent and minute universe intergalactic opacity of 0.01 mag h Gpc−1 at the local Universe have a significant impact on the EBL because obscuration of galaxies and density of intergalactic ...

KiDS-450: cosmological parameter constraints from tomographic weak gravitational lensing

We present cosmological parameter constraints from a tomographic weak gravitational lensing analysis of ∼450 deg2 of imaging data from the Kilo Degree Survey (KiDS). For a flat Λ cold dark matter (ΛCDM) cosmology with a prior on H0 that encompasses the most recent direct measurements, we find $S_8\equiv \sigma _8\sqrt{\Omega _{\rm m}/0.3}=0.745\pm 0.039$. This result is in good ...

High-precision limit on variation in the fine-structure constant from a single quasar absorption system

The brightest southern quasar above redshift z = 1, HE 0515−4414, with its strong intervening metal absorption line system at zabs = 1.1508, provides a unique opportunity to precisely measure or limit relative variations in the fine-structure constant (Δα/α). A variation of just ∼3 parts per million (ppm) would produce detectable velocity shifts between its many strong metal ...

GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey – I. A low-frequency extragalactic catalogue

Using the Murchison Widefield Array (MWA), the low-frequency Square Kilometre Array precursor located in Western Australia, we have completed the GaLactic and Extragalactic All-sky MWA (GLEAM) survey, and present the resulting extragalactic catalogue, utilizing the first year of observations. The catalogue covers 24 831 square degrees, over declinations south of +30° and Galactic ...

A LOFAR mini-survey for low-frequency radio emission from the nearest brown dwarfs

We have conducted a mini-survey for low-frequency radio emission from some of the closest brown dwarfs to the Sun with rapid rotation rates: SIMP J013656.5+093347, WISEPC J150649.97+702736.0 and WISEPA J174124.26+255319.5. We have placed robust 3σ upper limits on the flux density in the 111–169 MHz frequency range for these targets: WISE 1506: <0.72 mJy; WISE 1741: <0.87 mJy; SIMP ...

Inference of magnetic field in the coronal streamer invoking kink wave motions generated by multiple EUV waves

We analyse the observations from Solar TErrestrial RElations Observatory (STEREO) of an oscillating coronal streamer. STEREO-B Extreme Ultraviolet Imaging (EUVI) temporal data on 2012 March 7 show an evolution of two consecutive EUV waves that interact with footpoint of a coronal streamer clearly evident in the co-spatial and co-temporal STEREO-B/COR-1 observations. The waves are ...

A PSF-based approach to Kepler/K2 data – II. Exoplanet candidates in Praesepe (M 44)★

In this work, we keep pushing K2 data to a high photometric precision, close to that of the Kepler main mission, using a point-spread function (PSF)-based, neighbour-subtraction technique, which also overcome the dilution effects in crowded environments. We analyse the open cluster M 44 (NGC 2632), observed during the K2 Campaign 5, and extract light curves of stars imaged on ...

About AGN ionization echoes, thermal echoes and ionization deficits in low-redshift Lyα blobs

We report the discovery of 14 Lyα blobs (LABs) at z ∼ 0.3, existing at least 4–7 billion years later in the Universe than all other LABs known. Their optical diameters are 20–70 kpc, and GALEX data imply Lyα luminosities of (0.4–6.3) × 1043 erg s−1. Contrary to high-z LABs, they live in low-density areas. They are ionized by AGN, suggesting that cold accretion streams as a power ...

On the resonant detonation of sub-Chandrasekhar mass white dwarfs during binary inspiral

White dwarfs (WDs) are believed to detonate via explosive Carbon-fusion in a Type Ia supernova (SN) when their temperature and/or density reach the point where Carbon is ignited in a runaway reaction. Observations of the Type Ia SN rate imply that all WD binaries that merge through the emission of gravitational radiation within a Hubble time should result in SNe, regardless of ...

Modelling the evolution of a comet subsurface: implications for 67P/Churyumov–Gerasimenko

Modelling the evolution of comets is a complex task aiming at providing constraints on physical processes and internal properties that are inaccessible to observations, although they could potentially bring key elements to our understanding of the origins of these primitive objects. This field has made a tremendous step forward in the post-Giotto area, owing to detailed space- and ...