Browsing by Author "Morales-Garoffolo, A."

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The evolution of luminous red nova at 2017jfs in NGC4470?
(2019-01-01) Pastorello, A.; Chen, T. W.; Cai, Y. Z.; Morales-Garoffolo, A.; Cano, Z.; Mason, E.; Barsukova, E. A.; Benetti, S.; Berton, M.; Bose, S.; Bufano, F.; Callis, E.; Cannizzaro, G.; Cartier, R.; Chen, Ping; Dong, Subo; Dyrbye, S.; Elias-Rosa, N.; Flörs, A.; Fraser, M.; Geier, S.; Goranskij, V. P.; Kann, D. A.; Kuncarayakti, H.; Onori, F.; Reguitti, A.; Reynolds, T.; Losada, I. R.; Sagués Carracedo, A.; Schweyer, T.; Smartt, S. J.; Tatarnikov, A. M.; Valeev, A. F.; Vogl, C.; Wevers, T.; De Ugarte Postigo, A.; Izzo, L.; Inserra, C.; Kankare, E.; Maguire, K.; Smith, K. W.; Stalder, B.; Tartaglia, L.; Thöne, C. C.; Valerin, G.; Young, D. R.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
We present the results of our photometric and spectroscopic follow-up of the intermediate-luminosity optical transient AT 2017jfs. At peak, the object reaches an absolute magnitude of Mg = -15:46 ± 0:15 mag and a bolometric luminosity of 5:5 × 1041 erg s-1. Its light curve has the doublepeak shape typical of luminous red novae (LRNe), with a narrow first peak bright in the blue bands, while the second peak is longer-lasting and more luminous in the red and near-infrared (NIR) bands. During the first peak, the spectrum shows a blue continuum with narrow emission lines of H and Fe II. During the second peak, the spectrum becomes cooler, resembling that of a K-type star, and the emission lines are replaced by a forest of narrow lines in absorption. About 5 months later, while the optical light curves are characterized by a fast linear decline, the NIR ones show a moderate rebrightening, observed until the transient disappears in solar conjunction. At these late epochs, the spectrum becomes reminiscent of that of M-type stars, with prominent molecular absorption bands. The late-time properties suggest the formation of some dust in the expanding common envelope or an IR echo from foreground pre-existing dust. We propose that the object is a common-envelope transient, possibly the outcome of a merging event in a massive binary, similar to NGC4490-2011OT1.
Luminous red novae : Stellar mergers or giant eruptions?
(2019-09-24) Pastorello, A.; Mason, E.; Taubenberger, S.; Fraser, M.; Cortini, G.; Tomasella, L.; Botticella, M. T.; Elias-Rosa, N.; Kotak, R.; Smartt, S. J.; Benetti, S.; Cappellaro, E.; Turatto, M.; Tartaglia, L.; Djorgovski, S. G.; Drake, A. J.; Berton, M.; Briganti, F.; Brimacombe, J.; Bufano, F.; Cai, Y-Z; Chen, S.; Christensen, E. J.; Ciabattari, F.; Congiu, E.; Dimai, A.; Inserra, C.; Kankare, E.; Magill, L.; Maguire, K.; Martinelli, F.; Morales-Garoffolo, A.; Ochner, P.; Pignata, G.; Reguitti, A.; Sollerman, J.; Spiro, S.; Terreran, G.; Wright, D. E.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
We present extensive datasets for a class of intermediate-luminosity optical transients known as luminous red novae. They show double-peaked light curves, with an initial rapid luminosity rise to a blue peak (at -13 to -15 mag), which is followed by a longer-duration red peak that sometimes is attenuated, resembling a plateau. The progenitors of three of them (NGC 4490-2011OT1, M 101-2015OT1, and SNhunt248), likely relatively massive blue to yellow stars, were also observed in a pre-eruptive stage when their luminosity was slowly increasing. Early spectra obtained during the first peak show a blue continuum with superposed prominent narrow Balmer lines, with P Cygni profiles. Lines of Fe II are also clearly observed, mostly in emission. During the second peak, the spectral continuum becomes much redder, H alpha is barely detected, and a forest of narrow metal lines is observed in absorption. Very late-time spectra (similar to 6 months after blue peak) show an extremely red spectral continuum, peaking in the infrared (IR) domain. H alpha is detected in pure emission at such late phases, along with broad absorption bands due to molecular overtones (such as TiO, VO). We discuss a few alternative scenarios for luminous red novae. Although major instabilities of single massive stars cannot be definitely ruled out, we favour a common envelope ejection in a close binary system, with possibly a final coalescence of the two stars. The similarity between luminous red novae and the outburst observed a few months before the explosion of the Type IIn SN 2011ht is also discussed.