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.

  • Figure caption: The Stokes I and Q/I profiles of the IR triplet of O I calculated in the FAL-C semi-empirical model for a line of sight with μ = 0.1. The positive reference direction for Stokes Q is the parallel to the nearest limb. Top panels: the Stokes
    We present multilevel radiative transfer modeling of the scattering polarization observed in the solar O I infrared triplet around 777 nm. We demonstrate that the scattering polarization pattern observed on the solar disk forms in the chromosphere, far above the photospheric region where the bulk of the emergent intensity profiles originate. We investigate the sensitivity of the polarization pattern to the thermal structure of the solar atmosphere and to the presence of weak magnetic fields (0.01 –100 G) through the Hanle effect, showing that the scattering polarization signals of the oxygen
    Advertised on
  • Keck and GTC spectra for the microquasar ULS-1 in M81. (a) Labeled over the lines are the broad Balmer lines (Hα and Hβ), the very broad blue-shifted H-α at 564.8 nm and roughly symmetric red-shifted H+α at 752.4 nm. The power-law like continuum and the b
    Microquasars are compact binary stars (a normal very massive star and a compact object), which have an accretion disk around the compact object and an intense and variable radio emission, normally as bipolar jets (symmetric jets of matter in opposite directions). The unusual characteristic of the discovered microquasar in M81 is that the speed of the ejected material is close to the speed of light (that is known as relativistic jets), with a measured velocity of 17% that of light. The main properties of this microquasar all point to a black hole accreting at rates far exceeding the critical
    Advertised on
  • Figure caption: Zooming into the core of the sigma Orionis cluster, from the Orion constellation to the sigma Ori Aa,Ab,B triple system. Image credits: Gabriel Pérez (SMM, IAC), Sergio Simón-Díaz (IAC/ULL) and J.A. Caballero (CAB/CSIC), from a composition
    We provide a complete characterization of the astrophysical properties of the σ Ori Aa, Ab, B hierarchical triple system and an improved set of orbital parameters for the highly eccentric σ Ori Aa, Ab spectroscopic binary. We compiled a spectroscopic data set comprising 90 high-resolution spectra covering a total time span of 1963 days. We applied the Lehman-Filhés method for a detailed orbital analysis of the radial velocity curves and performed a combined quantitative spectroscopic analysis of the σ Ori Aa, Ab, B system by means of the stellar atmosphere code FASTWIND. We used our own plus
    Advertised on
  • Figure caption: Astronomy, architecture, and symbolism at Dahshur: the Red (left) and Bent (right) Pyramids as symbolic representation of the Red and White Crowns, respectively, as petrified counterparts of relevant respective reddish and whitish celestia
    The two pyramids built during the Old Kingdom by the Fourth Dynasty King Sneferu at Dahshur are usually considered as two consecutive projects, the second – that of the Red Pyramid – being generated by a presumably failure of the first, the Bent Pyramid. In the present paper, we show that the archaeological proofs of such a scenario are far from obvious and that, on the contrary, a series of architectural, topographical, epigraphic, and astronomical hints point to a unitary project probably conceived from the very beginning in terms of the two pyramids and their annexes. Altogether the two
    Advertised on