Search Publications
Searching for the GD-1 stream progenitor in Gaia DR2 with direct N-body simulations
Bovy, Jo; Webb, Jeremy J.
We perform a large suite of direct N-body simulations aimed at revealing the location of the progenitor, or its remnant, of the GD-1 stream. Data from Gaia DR2 reveal that the GD-1 stream extends over ≈100°, allowing us to determine the stream's leading and trailing ends. Our models suggest that the length of the stream is consistent with a dynami…
The magnetic early B-type Stars II: stellar atmospheric parameters in the era of Gaia
Wade, G. A.; Neiner, C.; Shultz, M. E. +6 more
Atmospheric parameters determined via spectral modelling are unavailable for many of the known magnetic early B-type stars. We utilized high-resolution spectra together with non-local thermodynamic equilibrium models to measure effective temperatures Teff and surface gravities log g of stars for which these measurements are not yet avai…
Brown dwarf census with the Dark Energy Survey year 3 data and the thin disc scale height of early L types
Bechtol, K.; Smith, M.; Abbott, T. M. C. +46 more
In this paper we present a catalogue of 11 745 brown dwarfs with spectral types ranging from L0 to T9, photometrically classified using data from the Dark Energy Survey (DES) year 3 release matched to the Vista Hemisphere Survey (VHS) DR3 and Wide-field Infrared Survey Explorer (WISE) data, covering ≈2400 deg2 up to iAB = 22.…
Strong lensing reveals jets in a sub-microJy radio-quiet quasar
Jackson, N.; Sluse, D.; Stacey, H. R. +2 more
We present e-MERLIN and European VLBI Network observations which reveal unambiguous jet activity within radio-quiet quasar HS 0810+2554. With an intrinsic flux density of 880 nJy, this is the faintest radio source ever imaged. The findings present new evidence against the idea that radio-loud and radio-quiet quasars are powered by different underl…
The haloes and environments of nearby galaxies (HERON) - I. Imaging, sample characteristics, and envelope diameters
Sales, Laura; Kormendy, John; Rich, R. Michael +16 more
We use a dedicated 0.7-m telescope to image the haloes of 119 galaxies in the Local Volume to µr ∼ 28-30 mag arcsec-2. The sample is primarily from the Two Micron All Sky Survey Large Galaxy Atlas (Jarrett et al. 2003) and extended to include nearby dwarf galaxies and more distant giant ellipticals, and spans fully the …
The VISCACHA survey - I. Overview and first results
Piatti, Andrés E.; Barbuy, Beatriz; Bica, Eduardo +15 more
The VISCACHA (VIsible Soar photometry of star Clusters in tApii and Coxi HuguA) Survey is an ongoing project based on deep photometric observations of Magellanic Cloud star clusters, collected using the SOuthern Astrophysical Research (SOAR) telescope together with the SOAR Adaptive Module Imager. Since 2015 more than 200 h of telescope time were …
Evidence for an emerging disc wind and collimated outflow during an X-ray flare in the narrow-line Seyfert 1 galaxy Mrk 335
Kriss, G. A.; Fabian, A. C.; Pinto, C. +13 more
A triggered 140{ ks}XMM-Newton observation of the narrow-line Seyfert 1 (NLS1) Mrk 335 in 2015 December caught the active galaxy at its lowest X-ray flux since 2007. The NLS1 is relatively quiescent for the first {∼ }120{ ks} of the observation before it flares in brightness by a factor of about five in the last 20{ ks}. Although only part of the …
Stellar activity analysis of Barnard's Star: very slow rotation and evidence for long-term activity cycle
Rebolo, R.; Amado, P. J.; Caballero, J. A. +58 more
The search for Earth-like planets around late-type stars using ultrastable spectrographs requires a very precise characterization of the stellar activity and the magnetic cycle of the star, since these phenomena induce radial velocity (RV) signals that can be misinterpreted as planetary signals. Among the nearby stars, we have selected Barnard's S…
Expected intermediate-mass black holes in the Virgo cluster - I. Early-type galaxies
Soria, Roberto; Graham, Alister W.
We expand upon the AMUSE-Virgo survey which imaged 100 early-type Virgo cluster galaxies with the Chandra X-ray Observatory, and we place an emphasis on potential intermediate-mass black holes (IMBHs). Virgo early-type galaxies with absolute magnitudes M_B≳ -20.5 mag have B-band luminosities that scale with the square of the stellar velocity dispe…
Simulating and interpreting deep observations in the Hubble Ultra Deep Field with the JWST/NIRSpec low-resolution `prism'
Charlot, Stéphane; Chevallard, Jacopo; Maseda, Michael V. +16 more
The James Webb Space Telescope (JWST) will enable the detection of optical emission lines in galaxies spanning a broad range of luminosities out to redshifts z ≳ 10. Measurements of key galaxy properties, such as star formation rate and metallicity, through these observations will provide unique insight into, e.g. the role of feedback from stars a…