News

This section includes scientific and technological news from the IAC and its Observatories, as well as press releases on scientific and technological results, astronomical events, educational projects, outreach activities and institutional events.

  • Abundance ratios of oxygen, magnesium and silicon relative to iron for the five stars in the bulge discovered by APOGEE (black filled circles) and literature values for other populations in the bulge (open circles), halo (squares), thin disk (crosses) and
    Despite its importance for understanding the nature of early stellar generations and for constraining Galactic bulge formation models, at present little is known about the metal-poor stellar content of the central Milky Way. This is a consequence of the great distances involved and intervening dust obscuration, which challenge optical studies. However, the Apache Point Observatory Galactic Evolution Experiment (APOGEE), a wide-area, multifiber, high-resolution spectroscopic survey within Sloan Digital Sky Survey III (SDSS-III), is exploring the chemistry of all Galactic stellar populations
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  • This figure displays the results from the Bayesian comparison for coronal loop models as: M0: uniform flux tubes; M1: density stratified flux tubes; M2: expanding magnetic flux tubes. (a) Marginal likelihood as a function of the observed period ratio, r,
    We present the first application of Bayesian model comparison techniques for solar atmospheric seismology. The detection of multiple mode harmonic kink oscillations in coronal loops enables to obtain information on coronal density stratification and magnetic field expansion using seismology inversion techniques. The inference is based on the measurement of the period ratio between the fundamental mode and the first overtone and theoretical results for the period ratio under the hypotheses of coronal density stratification and magnetic field expansion of the wave guide. We present a Bayesian
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  • Rotation plays a key role in the life cycles of stars with masses above 8 Msun. Hence, accurate knowledge of the rotation rates of such massive stars is critical for understanding their properties and for constraining models of their evolution.This paper investigates the reliability of current methods used to derive projected rotation speeds v sin i from line-broadening signatures in the photospheric spectra of massive stars, focusing on stars that are not rapidly rotating.We use slowly rotating magnetic O-stars with well-determined rotation periods to test the Fourier transform (FT) and
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  • Upper panel: composite image of NGC 6946 obtained by adding all the wavelengths for the Hα scan. The circle indicates the position of region at RA: 308.6998566 degrees, DEC: +60.1772541 degrees. Lower panel: spectral energy distribution for Hα + [NII] (le
    Using the OSIRIS tunable narrow band imager on the 10.4m GTC (La Palma) we have mapped the SAB(rs)cd galaxy NGC 6946 over a 7.3x7.5 square arcminutes field in the emission lines of the [SII]\lambda\lambda, 6717, 6731 doublet, and in H\alpha. From these maps we have produced catalogs of the H\alpha luminosities and effective radii of 557 HII regions across the disk, and derived the [SII] emission line ratios of 370 of these. The H\alpha observations were used to derive the mean luminosity-weighted electron densities for the regions of the sample, while the [SII] line ratios allowed us to
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  • Redshift evolution of the ratio of the relic galaxies to the total number of massive galaxies. The three different lines represent the three considered models. Coloured areas, orange (orange-red) show galaxies that have increased their masses less than a
    The number of present-day massive galaxies that has survived untouched since their formation at high-z is an important observational constraint to the hierarchical galaxy formation models. Using three different semianalytical models based on the Millenium simulation, we quantify the expected fraction and number densities of the massive galaxies form at z>2 which have evolved in stellar mass less than 10% and 30%. We find that only a small fraction of the massive galaxies already form at z~2 have remained almost unaltered since their formation (<2% with Delta_M*/M*<0.1 and <8% with Delta_M*/M
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  • Image en banda z of a Y dwarf, WISE1217+1626. The red circle indicates the position of the Y dwarf on the GTC image whereas the black circle denominates the position of the discovery image.
    The aim of the project is to contribute to the characterisation of the spectral energy distribution of the coolest brown dwarfs discovered to date, the Y dwarfs.We obtained z-band far-red imaging for six Y dwarfs and a T9+Y0 binary with the OSIRIS (Optical System for Imaging and low Resolution Integrated Spectroscopy) instrument on the 10.4-m Gran Telescopio de Canarias (GTC).We detect five of the seven known Y dwarfs in the z-band, infer theioptical-to-infrared colours, and measure their proper motions. We find a higher dispersion in the z-J and z-H colours of Y0 dwarfs than in T dwarfs
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