ﻻ يوجد ملخص باللغة العربية
We present optical spectroscopic and photometric observations of Type Ia supernova (SN) 2006X from --10 to +91 days after the $B$-band maximum. This SN exhibits one of the highest expansion velocity ever published for SNe Ia. At premaximum phases, the spectra show strong and broad features of intermediate-mass elements such as Si, S, Ca, and Mg, while the O{sc i}$lambda$7773 line is weak. The extremely high velocities of Si{sc ii} and S{sc ii} lines and the weak O{sc i} line suggest that an intense nucleosynthesis might take place in the outer layers, favoring a delayed detonation model. Interestingly, Si{sc ii}$lambda$5972 feature is quite shallow, resulting in an unusually low depth ratio of Si{sc ii}$lambda$5972 to $lambda$6355, $cal R$(Si{sc ii}). The low $cal R$(Si{sc ii}) is usually interpreted as a high photospheric temperature. However, the weak Si{sc iii}$lambda$4560 line suggests a low temperature, in contradiction to the low $cal R$(Si{sc ii}). This could imply that the Si{sc ii}$lambda$5972 line might be contaminated by underlying emission. We propose that $cal R$(Si{sc ii}) may not be a good temperature indicator for rapidly expanding SNe Ia at premaximum phases.
We report initial observations and analysis on the Type IIb SN~2016gkg in the nearby galaxy NGC~613. SN~2016gkg exhibited a clear double-peaked light curve during its early evolution, as evidenced by our intensive photometric follow-up campaign. SN~2
We present extensive optical (UBVRI), near-infrared (JK) light curves and optical spectroscopy of the Type Ia supernova (SN) 2006X in the nearby galaxy NGC 4321 (M100). Our observations suggest that either SN 2006X has an intrinsically peculiar color
We present optical photometry and spectra for the Type Ia supernova (SN Ia) 2007gi in the nearby galaxy NGC 4036. SN 2007gi is characterized by extremely high-velocity (HV) features of the intermediate-mass elements (Si, Ca, and S), with expansion ve
We study the effect of different Type Ia SN nucleosynthesis prescriptions on the Milky Way chemical evolution. To this aim, we run detailed one-infall and two-infall chemical evolution models, adopting a large compilation of yield sets corresponding
We present photometry and time-series spectroscopy of the nearby type Ia supernova (SN Ia) SN 2015F over $-16$ days to $+80$ days relative to maximum light, obtained as part of the Public ESO Spectroscopic Survey of Transient Objects (PESSTO). SN 201