3.16 Instituto de Astrofísica

Permanent URI for this community

https://repositorio.uc.cl/handle/11534/21909

Browse

Browsing 3.16 Instituto de Astrofísica by Author "Clocchiatti, Alejandro"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Estimadores de metalicidad en SN tipo II-P
    (2023) Castro Morales, Nicolás Manuel; Clocchiatti, Alejandro; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
    Uno de los parámetros más difíciles de estimar en supernovas es su metalicidad, basicamente por lo complejo de sus espectros y por la imposibilidad de haber observado con el detalle apropiado al progenitor en la gran mayoría de los casos. Los espectros de las supernovas de tipo IIP durante la fase fotosférica, sin embargo, revelan información directa sobre la metalicidad de la estrella progenitora que es posible interpretar. Los pseudo anchos equivalentes de los perfiles P Cygni de líneas de elementos químicos complejos ya han sido utilizados como indicadores de metalicidad, pero tienen algunas limitaciones. Presentamos un nuevo método que añade a las líneas de los espectros un indicador fotométrico basado en la evolución del brillo de las supernovas en la banda B, y/o la U, de Johnson, siempre en supernovas tipo IIP. Usando modelos teóricos de la atmósfera en estas supernovas encontramos que la variación de la magnitud en B entre las fases temprana y tardía de la curva de luz (EtoLC, por las siglas en inglés, de ``Early to Late Contrast'') está relacionada tanto con la masa como con la metalicidad del progenitor. Mostramos además que con el uso combinado de los anchos equivalentes de una línea de hierro y estos EtoLCS es posible discriminar con bastante sensibilidad y separar supernovas provenientes de la explosión de progenitores muy masivos de las provenientes de progenitores poco masivos, así como los que tenían metalicidad elevada de los que la tenían baja. Utilizando esta técnica a una muestra de supernovas reales, con buenos conjuntos de datos como para poder medir estos parámetros, se encuentra concordancia con lo ilustrado por los modelos indicando que, una vez calibrado, el método tendrá el potencial de poder encontrar con observaciones directas las características de masa y metalicidad de los progenitores de SN tipo IIP.
  • Thumbnail Image
    Item
    Exploring Super-Chandrasekhar Supernova SN2007if with radiative transfer code TARDIS
    (2024) Silva Beyer, Joaquín; Clocchiatti, Alejandro; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
    Super-Chandrasekhar Supernovae (SNe) are a peculiar case of Type Ia SNthat show very high luminosities, slow light-curve evolution, and low expan-sion velocities, consistent with progenitor masses over the Chandrasekharlimit (≳ 1.4M⊙). SN 2007if is one of those events, with a still unknownexplosion scenario. Its early spectra are smooth and near featureless, butat later epochs, they seem to morph into a normal Type Ia. I exploredits spectra with radiative transfer code TARDIS, using three models, con-sidering the envelope interaction and the violent merger hypotheses. Thebest model, based on the envelope interaction scenario, resulted in a verygood match for early epochs, and a better match in the later epochs than theother models. I performed abundance tomography and adapted its chemicalstructure, resulting in my model 07if-tail. While it had a good agree-ment with the observed low velocities and some lines, many still featuredtoo deep absorption profiles, and the lines suggested a lower temperaturethan the overall continuum. I found that SN2007if probably lacks S and hasno Fe on its outer regions. In order to explain SN2007if’s light curve andspectra, a secondary source of continuum brightness is needed. My findingssupport the scenario of a WD-WD slow merger, forming a CO envelope thatinteracts with the explosion’s ejecta.
  • Thumbnail Image
    Item
    Supersoft X-rays nebulae in the Large Magellanic Cloud.
    (2019) Farías Hinojosa, Diego Andrés; Clocchiatti, Alejandro; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
    Supersoft X-rays binaries sources (SSSs) are said to be potential SN Ia progenitors. Surrounding these sources, due to X-rays emission of a steady-state accreting white dwarf (WD), there should be an associated [O III]λ5007 nebulae. If a SN Ia occurs at this SSS phase, these nebulae should be present in early images surrounding supernova remnants (SNRs). The aim of this work is to find these expected nebulae surrounding four SSSs, CAL 83, CAL 87, RX J0513.9-6751 and RX J0550.0-7151, and three SNRs, SNR 0509-67.5, SNR 0519.69.0 and SNR N103B, in the Large Magellanic Cloud (LMC). In order to do this, we obtain images from the Inamori Magellan Areal Camera and Spectrograph (IMACS) using a broadband Bessell V filter, and a narrowband [O III] filter, centered at ≈ 5007 ˚A. The images were processed by the pipeline PHOTPIPE, which does the astrometry, stacking and differencing of the images, the last step using the well-known HOTPANTS code. By measuring the flux around the coordinates of the source, we study the surface brightness profiles up to 25 pc of the diffuse nebula, to later compare them to the theoretical profiles made by the photoionization code CLOUDY. Our [O III] flux measurements for CAL 83 are consistent within 2σ with previous results (Remillard et al., 1995), probably due to systematic effects in our calibration technique. In spite of this quantitative difference we confirm that CAL 83 is the only SSS with an associated [O III] ionized region of the seven candidates. The [O III] luminosity for the other objects at 7.5 pc from the central source, are . 15% of that of CAL 83. CLOUDY models of the nebulae allow us to constrain physical conditions, such as the ISM density of the source. For typical SSS parameters e.g., luminosity between 1037 − 1037.5 erg/s and effective temperature of the order of 5 × 105 K, the density of the CAL 83 nebula at 7.5 pc is suspected to be slightly lower than, but still consistent with, the range of 4 − 10 cm−3 found by Remillard et al. (1995). For all the other regions, CLOUDY models indicate ISM densities unrealistically low to be consistent with the observed luminosity upper limits.
  • Thumbnail Image
    Item
    The extraplanar type II supernova ASASSN-14jb in the galaxy ESO 467-G051
    (2018) Meza Retamal, Nicolás Eduardo; Clocchiatti, Alejandro; Prieto Katunaric, José Luis; Pontificia Universidad Católica de Chile. Facultad de Física