HIGHLIGHTS

  • 2020

    DON'T STOP NOVAE

    • Ancients coined the term “novae” to describe the appearance of new stars in the sky that faded away after a few weeks or months. As comets and eclipses, these were considered premonition for future events. Nowadays, astronomers use this term to designate an explosive event on the surface of a white dwarf star, a compact stellar remnant with the mass of our Sun compressed to the size of the Earth. In a nova event, the material accreted onto the surface of the white dwarf from a late type binary companion reaches a critical mass and, under the effects of the high gravity of the white dwarf, a thermonuclear runaway is ignited. Material is ejected at speeds of hundreds to even a few thousands km/s in a nova explosion. This material forms a nova shell that expands swiftly, and soon can be resolved by space and ground-based telescopes.

      The expansion of nova shells can be witnessed in time-scales of decades or even only a few years in some cases (e.g., Sab 142, Santamaría et al. 2019). Textbook models based on simple assumptions predict that the expansion velocity of a nova shell slows down to 50% of its initial value after 50—100 years. To test this classical prediction, high-quality images of nova shells in astronomical archives have been complemented with contemporary sub-arcsec images obtained at the Nordic Optical Telescope in the island of La Palma to investigate the present expansion of five nova shells with ages ranging from 50 to 130 years (Santamaría et al. 2020). Contrary to the theoretical expectations, the nova shells in our sample have a free expansion that will take effect until their very end, when they dilute into the interstellar medium. Apparently, the mechanical energy and momentum of the material in a nova shell is sufficiently large to sweep away the circumstellar material around the white dwarf. The expansion of the nova shells included in this study is notable in the “timelapse” movie of DQ Her, a cataclysmic variable system that experienced an outburst on December 1934.




    EXTENDED X-RAY EMISSION FROM THE CLASSIC NOVA DQ HER -- ON THE POSSIBLE PRESENCE OF A MAGNETIZED JET

    Monthly Notices of the Royal Astronomical Society
    • Intrigued by the fast expansion of DQ Her, we used Chandra and XMM-Newton X-ray observations to investigate its hot gas content. The Chandra observations confirm previous claims on the presence of extended X-ray emission around DQ Her and reveals that it actually corresponds to a bipolar jet-like structure extending 32" along a direction from NE to SW, whereas the XMM-Newton observations detect diffuse X-ray emission from a hot bubble filling the nova shell. The synchrotron emission from the outflow reveals it is magnetised outflow, implying that the strong magnetic field of the intermediate polar white dwarf at the core of DQ Her has taken control of the material being accreted onto its surface after the nova event.




    H2 EMISSION IN THE LOW-IONIZATION STRUCTURES
    OF THE PLANETARY NEBULAE NGC 7009 AND NGC 6543

    Monthly Notices of the Royal Astronomical Society
    • Despite the many studies in the last decades, the low-ionization structures (LISs) of planetary nebulae (PNe) still hold several mysteries. Recent imaging surveys have demonstrated that LISs are composed of molecular gas. Here, we report H2 emission in the LISs of NGC 7009 and NGC 6543 by means of very deep narrow-band H2 images taken with NIRI@Gemini.




    Jesús Alberto Toalá Sanz
    Winner Cátedra de Investigación Marcos Moshinsky 2020

    • Fundación Marcos Moshinsky
      With this project, Jesús Toalá intend to search and characterise the extended X-ray emission produced in novae explosions through the analysis of high quality observations and unprecedented numerical simulations trying to search for clues in order to understand nova events.















  • 2019

    MEASURING THE EXPANSION AND AGE OF THE
    NOVA SHELL IPHASX J210204.7 + 471015

    • Monthly Notices of the Royal Astronomical Society
      Multi-epoch images and high-dispersion spectroscopic observations of the recently discovered classical nova shell IPHASX J210204.7 + 471015 around a nova-like system have been used to derive a present day expansion rate and an expansion velocity. (MNRAS 483, 3773–3780, 2019)




    HIDDEN IR STRUCTURES IN NGC40:
    SIGNPOST OF AN ANCIENT BORN-AGAIN EVENT

    • Monthly Notices of the Royal Astronomical Society
      We present the analysis of infrared (IR) observations of the planetary nebula NGC40 together with spectral analysis of its [WC]-type central starHD826. Spitzer IRS observations were used to produce spectral maps centred at polycyclic aromatic hydrocarbons (PAH) bands and ionic transitions to compare their spatial distribution. (MNRAS 485, 3360–3369, 2019)




    Laurence Sabin
    Winner Cátedra de Investigación Marcos Moshinsky 2019

    • Fundación Marcos Moshinsky
      Through the development of Magneto-Hydrodynamic models combined with polarimetric (spectrum and observations), Laurence Sabin will study the magnetic fields in evolved Solar-type stars. The project aims to define the dynamic effects of stellar magnetism on the envelopes of these objects and to study the processes of magnetic release of material.




















  • 2018

    THE INSIDE-OUT PLANETARY NEBULA AROUND A BORN AGAIN STAR

    • Nature Astronomy
      Here, we report on the exceptional case of HuBi1, a double-shell planetary nebula whose inner shell presents emission from low-ionization species close to the star and emission from high-ionization species farther away. Spectral analysis demonstrates that the inner shell of HuBi 1 is excited by shocks, whereas its outer shell is recombining. (Nature Astronomy | Vol 2 | October 2018 | 784–789)




























  • 2017

    HOT GAS IN THE WOLF-RAYET NEBULA NGC 3199

    • The Astrophysical Journal
      The Wolf–Rayet (WR) nebula NGC 3199 has been suggested to be a bow shock around its central star, WR 18, which is presumably a runaway star, because optical images of the nebula show a dominating arc of emission southwest of the star. We present the XMM-Newton detection of extended X-ray emission from NGC 3199, unveiling the powerful effect of the fast wind from WR 18. The X-ray emission is brighter in the region southeast of the star and an analysis of the spectral properties of the X-ray emission reveals abundance variations.




    PUSHING THE LIMITS: DETECTING H2 EMISSION FROM FAINT
    BIPOLAR PLANETARY NEBULAE IN THE IPHAS SAMPLE

    • Monthly Notices of the Royal Astronomical Society
      We have obtained deep narrowband images in the near-infrared H2 λ2.122 μm emission line for a sample of 15 faint Isaac Newton Telescope Photometric Hα Survey (IPHAS) bipolar planetary nebulae (PNe) to search for molecular material. H2 emission is found in most of them (14 out of 15), mostly associated with rings at their equatorial regions and with their bipolar lobes. These detections add to the high occurrence of H2 emission among bipolar PNe reported in previous works, resulting from the large reservoir of molecular material in these sources and the suitable excitation conditions for H2 emission.





    Gerardo Ramos Larios
    Winner Cátedra de Investigación Marcos Moshinsky 2017

    • Fundación Marcos Moshinsky
      Through high-resolution 2D hydrodynamic simulations, our group studied evolved stars and planetary nebulae that have rings and arcs around them. We found that the interaction of the central star's fast wind and the ionization flux, eventually disrupt and destroy these arcs and rings.








  • Gallery
      Morelia, Mexico 2018
      Guadalajara, Mexico 2019
      APN7, Hong Kong 2017

      Granada, Spain 2018
      Granada, Spain 2019
      Granada, Spain 2019

      Granada, Spain 2018
      Ensenada, Mexico 2019
      Leiden, Netherlands 2019

      APN6, Mexico 2013
      OAN-SPM, Mexico 2020
      Morelia, Mexico 2019






Contact:
Group for the Research on Nebulae around Evolved Stars
group.rnes@gmail.com