F. Di Mille

SN 2005cs in M51 – II. Complete evolution in the optical and the near-infrared

We present the results of the one-year long observational campaign of the type II plateau SN 2005cs, which exploded in the nearby spiral galaxy M51 (the Whirlpool galaxy). This extensive data set makes SN 2005cs the best observed low-luminosity, ^(56)Ni-poor type II plateau event so far and one of the best core-collapse supernovae ever. The optical and near-infrared spectra show narrow P-Cygni lines characteristic of this SN family, which are indicative of a very low expansion velocity (about 1000 km s^(−1) ) of the ejected material. The optical light curves cover both the plateau phase and the late-time radioactive tail, until about 380 d after core-collapse. Numerous unfiltered observations obtained by amateur astronomers give us the rare opportunity to monitor the fast rise to maximum light, lasting about 2 d. In addition to optical observations, we also present near-infrared light curves that (together with already published ultraviolet observations) allow us to construct for the first time a reliable bolometric light curve for an object of this class. Finally, comparing the observed data with those derived from a semi-analytic model, we infer for SN 2005cs a ^(56)Ni mass of about 3 × 10^(−3) M⊙, a total ejected mass of 8–13 M⊙ and an explosion energy of about 3 × 10^(50) erg .

Exploring Narrow-Line Seyfert 1 Galaxies through the Physical Properties of Their Hosts*

In this work we address the still open question of the nature of narrow-line Seyfert 1 galaxies (NLS1s): are they really active nuclei with lower mass black holes (BHs) than Seyfert 1 galaxies (S1s) and quasars? Our approach is based on the recently discovered physical connections between nuclear supermassive BHs and their hosting spheroids (spiral bulges or elliptical galaxies). In particular, we compare BH masses of NLS1s and S1s, analyzing the properties of their hosts by means of spectroscopic and photometric data in the optical wavelength domain. We find that NLS1s fill the low BH mass and bulge luminosity values of the MBH-MB relation, a result strongly suggesting that NLS1s are active nuclei in which less massive BHs are hosted by less massive bulges. The correlation is good, with a relatively small scatter fitting simultaneously NLS1s, S1s, and quasars. On the other hand, NLS1s seem to share the same stellar velocity dispersion range as S1s in the MBH-σ* relation, indicating that NLS1s have a smaller BH/bulge mass ratio than S1s. These two conflicting results support in any case the idea that NLS1s could be young S1s. Finally, we do not confirm the significantly nonlinear BH-bulge relation claimed by some authors.

The carbon-rich type Ic SN 2007gr: the photospheric phase

The first 2 months of spectroscopic and photometric monitoring of the nearby Type Ic SN 2007gr are presented. The very early discovery (less than 5 days after the explosion) and the relatively short distance of the host galaxy motivated an extensive observational campaign. SN 2007gr shows an average peak luminosity but unusually narrow spectral lines and an almost flat photospheric velocity profile. The detection of prominent carbon features in the spectra is shown and suggests a wide range in carbon abundance in stripped-envelope supernovae. SN 2007gr may be an important piece in the puzzle of the observed diversity of CC SNe.

A spectroscopic analysis of a sample of narrow-line Seyfert 1 galaxies selected from the Sloan Digital Sky Survey

We revisited the spectroscopic characteristics of narrow-line Seyfert 1 galaxies (NLS1s) by analysing a homogeneous sample of 296 NLS1s at redshift between 0.028 and 0.345, extracted from the Sloan Digital Sky Survey (SDSS-DR7) public archive. We confirm that NLS1s are mostly characterized by Balmer lines with Lorentzian profiles, lower black hole masses and higher Eddington ratios than classic broad-line Seyfert 1 (BLS1s), but they also appear to be active galactic nuclei (AGNs) contiguous with BLS1s and sharing with them common properties. Strong Fe II emission does not seem to be a distinctive property of NLS1s, as low values of Fe II/H

Balmer Emission Line Profiles and Complex Properties of Broad-Line Regions in Active Galactic Nuclei

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The origin of gas in extended narrow-line regions of nearby Seyfert galaxies – I. NGC 7212

are equally observed in these AGNs. Our data indicate that Fe II and Ca II kinematics are consistent with the one of H

[O III] line properties in two samples of radio-emitting narrow-line Seyfert 1 galaxies

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New photometric and spectroscopic observations of the Seyfert galaxy Mrk 315

. On the contrary, O I

Symbiotic Stars in OGLE Data I. Large Magellanic Cloud Systems

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Monitoring the late decline of the old nova RW Ursae Minoris

8446 seems to be systematically narrower and it is likely emitted by gas of the broad-line region more distant from the ionizing source and showing different physical properties. Finally, almost all NLS1s of our sample show radial motions of the narrow-line region highly-ionised gas. The mechanism responsible for this effect is not yet clear, but there are hints that very fast outflows require high continuum luminosities (>