We report the results of a 3 year-long dedicated monitoring campaign of a restless Luminous Blue Variable (LBV) in NGC 7259. The object, named SN 2009ip, was observed photometrically and spectroscopically in the optical and near-infrared domains. We monitored a number of erupting episodes in the past few years, and increased the density of our observations during eruptive episodes. In this paper we present the full historical data set from 2009-2012 with multi-wavelength dense coverage of the two high luminosity events between August -September 2012. We construct bolometric light curves and measure the total luminosities of these eruptive or explosive events. We label them the 2012a event (lasting ∼ 50 days) with a peak of 3 × 10 41 ergs −1 , and the 2012b event (14 day rise time, still ongoing) with a peak of 8 × 10 42 ergs −1 . The latter event reached an absolute Rband magnitude of about -18, comparable to that of a core-collapse supernova (SN). Our historical monitoring has detected high-velocity spectral features (∼13000 km s −1 ) in September 2011, one year before the current SN-like event. This implies that the detection of such high velocity outflows cannot, conclusively, point to a core-collapse SN origin. We suggest that the initial peak in the 2012a event was unlikely to be due to a faint core-collapse SN. We propose that the high intrinsic luminosity of the latest peak, the variability history of SN 2009ip, and the detection of broad spectral lines indicative of high-velocity ejecta are consistent with a pulsational pair-instability event, and that the star may have survived the last outburst. The question of the survival of the LBV progenitor star and its future fate remain open issues, only to be answered with future monitoring of this historically unique explosion.
We present an extensive optical and near-infrared photometric and spectroscopic campaign of the type IIP supernova SN 2012aw. The dataset densely covers the evolution of SN 2012aw shortly after the explosion up to the end of the photospheric phase, with two additional photometric observations collected during the nebular phase, to fit the radioactive tail and estimate the 56 Ni mass. Also included in our analysis is the already published Swift UV data, therefore providing a complete view of the ultraviolet-optical-infrared evolution of the photospheric phase. On the basis of our dataset, we estimate all the relevant physical parameters of SN 2012aw with our radiation-hydrodynamics code: envelope mass M env ∼ 20M ⊙ , progenitor radius R ∼ 3 × 10 13 cm (∼ 430R ⊙ ), explosion energy E ∼ 1.5 foe, and initial 56 Ni mass ∼ 0.06 M ⊙ . These mass and radius values are reasonably well supported by independent evolutionary models of the progenitor, and may suggest a progenitor mass higher than the observational limit of 16.5 ± 1.5M ⊙ of the Type IIP events.
We present the spectroscopic and photometric study of five intermediate-luminosity red transients (ILRTs), namely AT 2010dn, AT 2012jc, AT 2013la, AT 2013lb, and AT 2018aes. They share common observational properties and belong to a family of objects similar to the prototypical ILRT SN 2008S. These events have a rise time that is less than 15 days and absolute peak magnitudes of between −11.5 and −14.5 mag. Their pseudo-bolometric light curves peak in the range 0.5–9.0 × 1040 erg s−1 and their total radiated energies are on the order of (0.3–3) × 1047 erg. After maximum brightness, the light curves show a monotonic decline or a plateau, resembling those of faint supernovae IIL or IIP, respectively. At late phases, the light curves flatten, roughly following the slope of the 56Co decay. If the late-time power source is indeed radioactive decay, these transients produce 56Ni masses on the order of 10−4 to 10−3 M⊙. The spectral energy distribution of our ILRT sample, extending from the optical to the mid-infrared (MIR) domain, reveals a clear IR excess soon after explosion and non-negligible MIR emission at very late phases. The spectra show prominent H lines in emission with a typical velocity of a few hundred km s−1, along with Ca II features. In particular, the [Ca II] λ7291,7324 doublet is visible at all times, which is a characteristic feature for this family of transients. The identified progenitor of SN 2008S, which is luminous in archival Spitzer MIR images, suggests an intermediate-mass precursor star embedded in a dusty cocoon. We propose the explosion of a super-asymptotic giant branch star forming an electron-capture supernova as a plausible explanation for these events.
We present a study of optical spectra of the Wolf–Rayet star AzV 336a (=SMC WR7) in the Small Magellanic Cloud. Our study is based on data obtained at several Observatories between 1988 and 2001. We find SMC WR7 to be a double‐lined WN+O6 spectroscopic binary with an orbital period of 19.56 d. The radial velocities of the He absorption lines of the O6 component and the strong He ii emission at λ4686 Å of the WN component describe anti‐phased orbital motions. However, they show a small phase shift of ∼1 d. We discuss possible explanations for this phase shift. The amplitude of the radial velocity variations of He ii emission is twice that of the absorption lines. The binary components have fairly high minimum masses, ∼18 and 34 M⊙ for the WN and O6 components, respectively.
El presente trabajo se propone analizar el modo en que los saberes psi definieron ciertas concepciones en torno a la maternidad y la infancia, difundidas a través de la revista Madre y Niño, publicada en la Argentina a mediados de la década de 1930. La utilización de la psicología contribuyó a la legitimación del saber médico sobre la infancia a partir de definir su especificidad y combatir las nociones y prácticas populares, consideradas perjudiciales y anticientíficas. En la Argentina, la articulación de tales discursos y prácticas ha configurado el proceso de disciplinarización e institucionalización de la psicología y su utilización por parte de los saberes médicos como una estrategia de intervención social.
Observations of WR stars in binary systems are discussed, emphasizing constraints on our knowledge of the binary frequency of WR stars, and of WR stars as a distinctive class of objects. Radial velocity orbits of newly discovered binaries, e.g., WR29, a short period WN7+0B binary in our Galaxy, and SMCjAB7, a massive WN+07 binary in the Small Magellanic Cloud, are presented. New spectroscopic observations of binary systems with previously known orbits are also reported, showing in the case of WR 21 evidence of change of the orbital elements as derived from different spectral lines. An elliptic orbit for CV Ser is also illustrated.
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