Related papers: CO-Driven Activity in Comet C/2017 K2 (PANSTARRS)
The discovery of interstellar comet 2I/Borisov offered the unique opportunity to obtain a detailed analysis of an object coming from another planetary system, and leaving behind material in our interplanetary space. We continuously observed…
On 21 March 2013 high-resolution slit spectrographs of comet C/2011 L4 (Panstarrs), at the heliocentric distance r = 0.46 Astronomical Units (AU), were obtained at the Osservatorio Astronomico Campo dei Fiori, Italy. Emission lines of…
We present observations using the Baade Magellan and Canada-France-Hawaii telescopes showing that main-belt comet 324P/La Sagra, formerly known as P/2010 R2, has become active again for the first time since originally observed to be active…
Infrared observations of the coma of 67P/Churyumov-Gerasimenko were carried out from July to September 2015, i.e., around perihelion (13 August 2015), with the high-resolution channel of the VIRTIS instrument onboard Rosetta. We present the…
We extend an existing thermophysical activity model of comet 67P/Churyumov-Gerasimenko to include pressure buildup inside the pebbles making up the nucleus. We test various quantities of H$_{2}$O and CO$_{2}$, in order to simulate the…
Here we report that the activity of comet Hale--Bopp ceased between late 2007 and March, 2009, at about 28 AU distance from the Sun. At that time the comet resided at a distance from the Sun that exceeded the freeze-out distance of regular…
Comet 7P/Pons-Winnecke was observed from the Calar Alto Observatory (Spain) for four months during the 2021 inbound apparition. Broad-band visible images were taken between 1.71 and 1.25 AU pre-perihelion, while long-slit spectrophotometric…
The ionisation cones of NGC5728 have a deficit of molecular gas based on millimetre observations of CO(2-1) emission. Although photoionisation from the active nucleus may lead to suppression of this transition, warm molecular gas can still…
The recently announced Oort-cloud comet C/2014 UN271 (Bernardinelli-Bernstein) is remarkable in at least three respects: (i) it was discovered inbound as far as ~29 au from the Sun (with prediscovery images up to ~34 au); (ii) it showed…
The population of comets hosted by the Oort cloud is heterogeneous. Most studies in this area focused on highly active objects, those with small perihelion distances or examples of objects with peculiar physical properties and/or unusual…
We analyzed spectral cubes of Callisto's leading and trailing hemispheres, collected with the NIRSpec Integrated Field Unit (G395H) on the James Webb Space Telescope. These spatially resolved data show strong 4.25-micron absorption bands…
Methods. We algorithmically tracked thousands of individual particles through four OSIRIS/NAC image sequences of 67P's near-nucleus coma. We then traced concentrated particle groups back to the nucleus surface, and estimated their potential…
We present high-resolution $^{12}$CO and $^{13}$CO 2-1 ALMA observations, as well as optical and near-infrared spectroscopy, of the highly-inclined protoplanetary disk around SSTC2D J163131.2-242627. The spectral type we derive for the…
Aims. Rotation periods of cometary nuclei are scarce, though important when studying the nature and origin of these objects. Our aim is to derive a rotation period for the nucleus of comet C/2004 Q2 (Machholz). Methods. C/2004 Q2 (Machholz)…
We report Spitzer Space Telescope observations of comet 67P/Churyumov-Gerasimenko at 5.5 and 4.3 AU from the Sun, post-aphelion. Comet 67P is the primary target of the European Space Agency's Rosetta mission. The Rosetta spacecraft will…
We present a study of two newly discovered heliocentric hyperbolic objects -- 2017 U7 and 2018 C2. Both are possibly thermally evolved comets. Observations of the latter in 2018 March from Xingming Observatory revealed that it has a color…
We present APEX 218 GHz observations of molecular emission in a complete sample of embedded protostars in the Ophiuchus star-forming region. To study the physical properties of the cores, we calculate H$_2$CO and c-C$_3$H$_2$ rotational…
We present unique spectroscopic radio observations of comets C/2002 X5 (Kudo-Fujikawa), C/2002 V1 (NEAT), and C/2006 P1 (McNaught), which came within $r_h ~ 0.2 AU of the Sun in 2003 and 2007. The molecules OH, HCN, HNC, CS, and CH3OH were…
Context: CO is an abundant species in comets, creating CO$^+$ ion with emission lines that can be observed in the optical spectral range. A good modeling of its fluorescence spectrum is important for a better measurement of the CO$^+$…
The discovery of the transient Jupiter co-orbital comet P/2019 LD2 (ATLAS) drew significant interest. Not only will LD2 transition between being a Centaur and a Jupiter Family Comet (JFC) in 2063, the first time this process can be observed…