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Probable detection of hydrogen sulphide (H2S) in Neptune's atmosphere
Fletcher, Leigh N.; Bézard, Bruno; Irwin, Patrick G. J. +4 more
Recent analysis of Gemini-North/NIFS H-band (1.45-1.8 µm) observations of Uranus, recorded in 2010, with recently updated line data has revealed the spectral signature of hydrogen sulphide (H2S) in Uranus's atmosphere (Irwin et al., 2018). Here, we extend this analysis to Gemini-North/NIFS observations of Neptune recorded in 2009 …
Optically Faint Massive Balmer Break Galaxies at z > 3 in the CANDELS/GOODS Fields
Barro, Guillermo; Pérez-González, Pablo G.; Eliche-Moral, M. Carmen +7 more
We present a sample of 33 Balmer break galaxies (BBGs) selected as Hubble Space Telescope/F160W dropouts in the deepest CANDELS/GOODS fields (H ≳ 27.3 mag) but relatively bright in Spitzer/IRAC ([3.6], [4.5] < 24.5 mag), implying red colors (median and quartiles: < H-[3.6]> ={3.1}2.83.4 {mag}). Half of these BBGs are…
General Physical Properties of Gamma-Ray-emitting Narrow-line Seyfert 1 Galaxies
Ajello, M.; Fabian, A. C.; Brenneman, L. +4 more
We present the results of a detailed multiwavelength study of a sample of 16 narrow-line Seyfert 1 (NLSy1) galaxies known in γ-rays so far. This includes a focused X-ray spectral analysis, to compare them with a more general NLSy1 population, and a broadband spectral energy distribution (SED) modeling considering the leptonic radiative processes t…
A Catalog of Wide Binary and Multiple Systems of Bright Stars from Gaia-DR2 and the Virtual Observatory
Solano, E.; Rodrigo, C.; Jiménez-Esteban, F. M.
Binary and multiple stars have long provided an effective empirical method of testing stellar formation and evolution theories. In particular, the existence of wide binary systems (separations >20,000 au) is particularly challenging to binary formation models as their physical separations are beyond the typical size of a collapsing cloud core (…
Non-LTE chemical abundances in Galactic open and globular clusters
Ting, Yuan-Sen; Kovalev, Mikhail; Rix, Hans-Walter +1 more
Aims: We study the effects of non-local thermodynamic equilibrium (NLTE) on the determination of stellar parameters and abundances of Fe, Mg, and Ti from the medium-resolution spectra of FGK stars.
Methods: We extended the Payne fitting approach to draw on NLTE and LTE spectral models. These were used to analyse the spectra of the Gaia-E…
Stringent limits on the magnetic field strength in the disc of TW Hya. ALMA observations of CN polarisation
Testi, L.; Williams, J. P.; Facchini, S. +8 more
Despite their importance in the star formation process, measurements of magnetic field strength in proto-planetary discs remain rare. While linear polarisation of dust and molecular lines can give insight into the magnetic field structure, only observations of the circular polarisation produced by Zeeman splitting provide a direct measurement of m…
H α morphologies of star clusters: a LEGUS study of H II region evolution time-scales and stochasticity in low-mass clusters
Herrero, A.; Cignoni, M.; Calzetti, D. +25 more
The morphology of H II regions around young star clusters provides insight into the time-scales and physical processes that clear a cluster's natal gas. We study ∼700 young clusters (≤10 Myr) in three nearby spiral galaxies (NGC 7793, NGC 4395, and NGC 1313) using Hubble Space Telescope (HST) imaging from LEGUS (Legacy ExtraGalactic Ultraviolet Su…
A Photometric and Spectroscopic Investigation of the DB White Dwarf Population Using SDSS and Gaia Data
Genest-Beaulieu, C.; Bergeron, P.
We present a comprehensive analysis of DB white dwarfs drawn from the Sloan Digital Sky Survey, based on model fits to ugriz photometry and medium-resolution spectroscopy from the Sloan Digital Sky Survey. We also take advantage of the exquisite trigonometric parallax measurements recently obtained by the Gaia mission. Using the so-called photomet…
Quasar and galaxy classification in Gaia Data Release 2
Fouesneau, Morgan; Bailer-Jones, Coryn A. L.; Andrae, Rene
We construct a supervised classifier based on Gaussian Mixture Models to probabilistically classify objects in Gaia data release 2 (GDR2) using only photometric and astrometric data in that release. The model is trained empirically to classify objects into three classes - star, quasar, galaxy - for G ≥ 14.5 mag down to the Gaia magnitude limit of …
Separating extended disc features from the protoplanet in PDS 70 using VLT/SINFONI
Pinte, C.; Quanz, S. P.; Casassus, S. +12 more
Transition discs are prime targets to look for protoplanets and study planet-disc interactions. We present VLT/SINFONI observations of PDS 70, a transition disc with a recently claimed embedded protoplanet. We take advantage of the angular and spectral diversity present in our data for an optimal PSF modelling and subtraction using principal compo…