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: Simulation of the magnetic field distribution (represented by lines whose lengths are proportional to the field strength) in a “cool” white dwarf. The darker zone is a cooler region where the intense magnetic field has partially blocked th
    Isolated cool white dwarf stars more often have strong magnetic fields than young, hotter white dwarfs which has been a puzzle because magnetic fields are expected to decay with time but a cool surface suggests that the star is old. In addition, some white dwarfs with strong fields vary in brightness as they rotate, which has been variously attributed to surface brightness inhomogeneities similar to sunspots, chemical inhomogeneities  and other magnetooptical effects. Here we describe optical observations of the brightness and magnetic field of the cool white dwarf WD1953-011 taken over
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  • Tc slopes versus ages for the full sample (top panel) and for the solar analogs (bottom panel). Gray solid lines provide linear fits to the data points.
    We explore a sample of 148 solar-like stars to search for a possible correlation between the slopes of the abundance trends versus condensation temperature (known as the Tc slope) with stellar parameters and Galactic orbital parameters in order to understand the nature of the peculiar chemical signatures of these stars and the possible connection with planet formation. We find that the Tc slope significantly correlates (at more than 4σ) with the stellar age and the stellar surface gravity (see Figure 1). We also find tentative evidence that the Tc slope correlates with the mean
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  • Figure caption: This is the spectrum of a massive AGB star (white dots) together with the predictions of the new model atmospheres (yellow line), and of the previous models which did not include the envelope (blue line). The Rubidium is detected as a very
    Intermediate mass stars, in their last phases of evolution ("AGB stars"),produce a large number of heavy elements (rich in neutrons), some ofthem radioactive isotopes, such as Rubidium and Technetium. Theseelements are pushed outwards to the surface of the star, and afterwards released into the interstellar medium. Among this type of stars, those least studied have been the more massive ones (between 4 and 8 times the mass of the Sun). Massive AGB stars have been recently identified in our Galaxy and in other nearby galaxies, such as the Magellanic Clouds, thanks to the detection of strong
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  • Figure caption: Grey scale representation of the probability density distribution of the location of 575 Galactic stars in the spectroscopic Hertzsprung-Russell diagram. Three empirical borderlines between densely populated regions and empty regions are d
    The distribution of stars in the Hertzsprung-Russell diagram narrates their evolutionary history and directly assesses their properties. Placing stars in this diagram however requires the knowledge of their distances and interstellar extinctions, which are often poorly known for Galactic stars. The spectroscopic Hertzsprung-Russell diagram (sHRD) tells similar evolutionary tales, but is independent of distance and extinction measurements. Based on spectroscopically derived effective temperatures and gravities of almost 600 stars, we derive for the first time the observational distribution of
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  • Figure 1:  Trailed intensity image showing the orbital evolution of two emission lines in MWC 656. Fe II 4,583 Å  is formed in the equatorial disc of the Be star while  He II 4,686 Å  arises from gas encircling the companion black hole.
    Stellar-mass black holes have all been discovered through X-ray emission, which arises from the accretion of gas from their binary companions (this gas is either stripped from low-mass stars or supplied as winds from massive ones). Binary evolution models also predict the existence of black holes accreting from the equatorial envelope of rapidly spinning Be-type stars (stars of the Be type are hot blue irregular variables showing characteristic spectral emission lines of hydrogen).  Of the ~80 Be X-ray binaries known in the Galaxy, however, only pulsating neutron stars have been found as
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  • Figure CaptionLeft: SDSS image of Mrk 709 (RGB=zrg), which appears to be a pair of interacting dwarf galaxies. We designate the northern and southern galaxies Mrk 709 N and Mrk 709 S. A logarithmic scaling is used to show extended emission. The white circ
    The incidence and properties of present-day dwarf galaxies hosting massive black holes (BHs) can provide important constraints on the origin of high-redshift BH seeds. Here we present high-resolution X-ray and radio observations of the low-metallicity, star-forming, dwarf-galaxy system Mrk 709 with the Chandra X-ray Observatory and the Karl G. Jansky Very Large Array (VLA). These data reveal spatially coincident hard X-ray and radio point sources with luminosities suggesting the presence of an accreting massive BH (M BH ∼ 10 5−7 M ⊙). Based on imaging from the Sloan Digital Sky Survey (SDSS)
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