Related papers: Further investigation of changes in cometary rotat…

The apparent source region (or regions) of long-period comets as well as the definition of the dynamically new comet are still open questions.The aim of this investigation is to look for the apparent source of selected long period comets…

Since very recently, we acquired knowledge on the existence of comets in extrasolar planetary systems. The formation of comets together with planets around host stars now seems evident. As stars are often born in clusters of interstellar…

Aims. We use four observational data sets, mainly from the Rosetta mission, to constrain the activity pattern of the nucleus of comet 67P/Churyumov-Gerasimenko. Methods. We develop a numerical model that computes the production rate and…

We report the results obtained from the optical polarimetric study of the light scattered by comets C/2013 V1 (Boattini) and 290P/Jager at lower phase angles. The polarimetric observations of two comets have been performed with the 1.04-m…

We observed comet C/2012 S1 (ISON) during six nights in February 2013 when it was at 4.8 AU from the sun. At this distance and time the comet was not very active and it was theoretically possible to detect photometric variations likely due…

The complete sample of large-perihelion nearly-parabolic comets discovered during the period 1901-2010 is studied starting from their orbit determination. Next, an orbital evolution that includes three perihelion passages…

We present imaging and spectroscopic data on comet 19P/Borrelly that were obtained around the time of the Deep Space 1 encounter and in subsequent months. In the four months after perihelion, the comet showed a strong primary (sunward) jet…

We performed a monitoring observation of a Jupiter-Family comet, 17P/Holmes, during its 2014 perihelion passage to investigate its secular change in activity. The comet has drawn the attention of astronomers since its historic outburst in…

We have been modeling the envelope of the secular light curve (Ferr\'in, 2010) of comet 1P/Halley. As the first step we have modeled the water production rate of the comet, for several active regions as a function of visual albedo and…

We numerically study the dynamical evolution of observed samples of active and inactive Centaurs and clones that reach the Jupiter-Saturn region. Our aim is to compare the evolution between active and inactive Centaurs, their end states and…

A number of planet-host stars have been observed to rotate with a period equal to an integer multiple of the orbital period of their close planet. We expand this list by analyzing Kepler data of HAT-P-11 and finding a period ratio of 6:1.…

It is speculated that some weakly active comets may be transitional objects between active and dormant comets. These objects are at a unique stage of the evolution of cometary nuclei, as they are still identifiable as active comets, in…

We obtained broadband and narrowband images of the hyperactive comet 46P/Wirtanen on 33~nights during its 2018/2019 apparition, when the comet made an historic close approach to the Earth. With our extensive coverage, we investigated the…

To date, at least three comets -- 2I/Borisov, C/2016 R2 (PanSTARRS), and C/2009 P1 (Garradd) -- have been observed to have unusually high CO concentrations compared to water. We attempt to explain these observations by modeling the effect…

Comet 41P/Tuttle-Giacobini-Kresak (41P), a Jupiter family comet with three discoveries over about 100 years, is in a short-periodic orbit around the Sun with the perihelion close to the Earth distance. The 2017 apparition of 41P offered a…

The chemical composition of comets is frequently assumed to be directly provided by the observations of the abundances of volatile molecules in the coma. The present work aims to determine the relationship between the chemical composition…

We report on narrowband photometry and extensive imaging observations of comet C/Lulin (2007 N3) obtained at Lowell Observatory during 2008 and 2009. Enhanced CN images revealed a double corkscrew morphology with two near-polar jets…

Comets hold the key to the understanding of our solar system, its formation and its evolution, and to the fundamental plasma processes at work both in it and beyond it. A comet nucleus emits gas as it is heated by the sunlight. The gas…

In this work we aim to characterise the dust motion in the inner coma of comet 67P/Churyumov- Gerasimenko to provide constraints for theoretical 3D coma models. The OSIRIS camera onboard the Rosetta mission was able for the first time to…

We present CCD VR_C observations of 6 distant comets located at heliocentric distances of 3.4--7.2 AU. Time-series data were obtained on three nights in July, 2000 covering 16 hours. Each comet was observed after the perihelion, when a…