Author
Stefano Mottola
Other affiliations: Max Planck Society, University of Padua
Bio: Stefano Mottola is an academic researcher from German Aerospace Center. The author has contributed to research in topics: Asteroid & Comet. The author has an hindex of 59, co-authored 286 publications receiving 12257 citations. Previous affiliations of Stefano Mottola include Max Planck Society & University of Padua.
Topics: Asteroid, Comet, Population, Physics, Geometric albedo
Papers published on a yearly basis
Papers
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TL;DR: Dawn's results confirm predictions that Vesta differentiated and support its identification as the parent body of the HEDs, and present the mineralogical characterization of Vesta, revealing that this asteroid underwent a complex magmatic evolution that led to a differentiated crust and mantle.
Abstract: The Dawn spacecraft targeted 4 Vesta, believed to be a remnant intact protoplanet from the earliest epoch of solar system formation, based on analyses of howardite-eucrite-diogenite (HED) meteorites that indicate a differentiated parent body. Dawn observations reveal a giant basin at Vesta's south pole, whose excavation was sufficient to produce Vesta-family asteroids (Vestoids) and HED meteorites. The spatially resolved mineralogy of the surface reflects the composition of the HED meteorites, confirming the formation of Vesta's crust by melting of a chondritic parent body. Vesta's mass, volume, and gravitational field are consistent with a core having an average radius of 107 to 113 kilometers, indicating sufficient internal melting to segregate iron. Dawn's results confirm predictions that Vesta differentiated and support its identification as the parent body of the HEDs.
470 citations
Max Planck Society1, University of Padua2, Aix-Marseille University3, International Space Science Institute4, Spanish National Research Council5, European Space Research and Technology Centre6, Uppsala University7, German Aerospace Center8, Braunschweig University of Technology9, University of Maryland, College Park10, Pierre-and-Marie-Curie University11, Centre national de la recherche scientifique12, INAF13, University of Trento14, Planetary Science Institute15, Macau University of Science and Technology16, National Central University17, European Space Agency18, NASA Lunar Science Institute19, Instituto Nacional de Técnica Aeroespacial20, University of Bern21, University of Cologne22
TL;DR: Images from the OSIRIS scientific imaging system onboard Rosetta show that the nucleus of 67P/Churyumov-Gerasimenko consists of two lobes connected by a short neck, which raises the question of whether the two Lobes represent a contact binary formed 4.5 billion years ago, or a single body where a gap has evolved via mass loss.
Abstract: Images from the OSIRIS scientific imaging system onboard Rosetta show that the nucleus of 67P/Churyumov-Gerasimenko consists of two lobes connected by a short neck. The nucleus has a bulk density less than half that of water. Activity at a distance from the Sun of >3 astronomical units is predominantly from the neck, where jets have been seen consistently. The nucleus rotates about the principal axis of momentum. The surface morphology suggests that the removal of larger volumes of material, possibly via explosive release of subsurface pressure or via creation of overhangs by sublimation, may be a major mass loss process. The shape raises the question of whether the two lobes represent a contact binary formed 4.5 billion years ago, or a single body where a gap has evolved via mass loss.
421 citations
INAF1, Parthenope University of Naples2, Max Planck Society3, Spanish National Research Council4, Aix-Marseille University5, International Space Science Institute6, European Space Agency7, Polish Academy of Sciences8, Uppsala University9, Braunschweig University of Technology10, University of Maryland, College Park11, University of Padua12, Paris Diderot University13, Versailles Saint-Quentin-en-Yvelines University14, European Space Research and Technology Centre15, Selex ES16, University of Trento17, Virginia Tech18, University of Florida19, Open University20, German Aerospace Center21, National Central University22, University of Kent23, University of Granada24, Centre national de la recherche scientifique25, Instituto Nacional de Técnica Aeroespacial26, University of Bern27, Jet Propulsion Laboratory28
TL;DR: In this article, the GIADA (Grain Impact Analyser and Dust Accumulator) experiment on the European Space Agency's Rosetta spacecraft orbiting comet 67P/Churyumov-Gerasimenko was used to detect 35 outflowing grains of mass 10−10 to 10−7 kilograms.
Abstract: Critical measurements for understanding accretion and the dust/gas ratio in the solar nebula, where planets were forming 4.5 billion years ago, are being obtained by the GIADA (Grain Impact Analyser and Dust Accumulator) experiment on the European Space Agency’s Rosetta spacecraft orbiting comet 67P/Churyumov-Gerasimenko. Between 3.6 and 3.4 astronomical units inbound, GIADA and OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) detected 35 outflowing grains of mass 10−10 to 10−7 kilograms, and 48 grains of mass 10−5 to 10−2 kilograms, respectively. Combined with gas data from the MIRO (Microwave Instrument for the Rosetta Orbiter) and ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) instruments, we find a dust/gas mass ratio of 4 ± 2 averaged over the sunlit nucleus surface. A cloud of larger grains also encircles the nucleus in bound orbits from the previous perihelion. The largest orbiting clumps are meter-sized, confirming the dust/gas ratio of 3 inferred at perihelion from models of dust comae and trails.
373 citations
INAF1, Pierre-and-Marie-Curie University2, German Aerospace Center3, University of Grenoble4, University of California, Los Angeles5, European Space Research and Technology Centre6, Centre national de la recherche scientifique7, University of Salento8, Polish Academy of Sciences9, California Institute of Technology10, University of Michigan11, University of Perugia12, University of Arizona13, National Central University14, University of Oxford15, Free University of Berlin16, Parthenope University of Naples17, Jet Propulsion Laboratory18, University of Maryland, College Park19
TL;DR: The VIRTIS instrument on board the Rosetta spacecraft has provided evidence of carbon-bearing compounds on the nucleus of the comet 67P/Churyumov-Gerasimenko, and no ice-rich patches are observed, indicating a generally dehydrated nature for the surface currently illuminated by the Sun.
Abstract: The VIRTIS (Visible, Infrared and Thermal Imaging Spectrometer) instrument on board the Rosetta spacecraft has provided evidence of carbon-bearing compounds on the nucleus of the comet 67P/Churyumov-Gerasimenko The very low reflectance of the nucleus (normal albedo of 0060 ± 0003 at 055 micrometers), the spectral slopes in visible and infrared ranges (5 to 25 and 15 to 5% kA−1), and the broad absorption feature in the 29-to-36–micrometer range present across the entire illuminated surface are compatible with opaque minerals associated with nonvolatile organic macromolecular materials: a complex mixture of various types of carbon-hydrogen and/or oxygen-hydrogen chemical groups, with little contribution of nitrogen-hydrogen groups In active areas, the changes in spectral slope and absorption feature width may suggest small amounts of water-ice However, no ice-rich patches are observed, indicating a generally dehydrated nature for the surface currently illuminated by the Sun
350 citations
University of Bern1, Max Planck Society2, University of Padua3, Aix-Marseille University4, Instituto Nacional de Técnica Aeroespacial5, Polish Academy of Sciences6, European Space Agency7, Braunschweig University of Technology8, German Aerospace Center9, University of Maryland, College Park10, Paris Diderot University11, Centre national de la recherche scientifique12, Uppsala University13, University of Trento14, INAF15, Spanish National Research Council16, National Central University17, NASA Lunar Science Institute18
TL;DR: Images of comet 67P/Churyumov-Gerasimenko acquired by the OSIRIS imaging system onboard the European Space Agency’s Rosetta spacecraft offer some support for subsurface fluidization models and mass loss through the ejection of large chunks of material.
Abstract: Images of comet 67P/Churyumov-Gerasimenko acquired by the OSIRIS (Optical, Spectroscopic and Infrared Remote Imaging System) imaging system onboard the European Space Agency’s Rosetta spacecraft at scales of better than 0.8 meter per pixel show a wide variety of different structures and textures. The data show the importance of airfall, surface dust transport, mass wasting, and insolation weathering for cometary surface evolution, and they offer some support for subsurface fluidization models and mass loss through the ejection of large chunks of material.
305 citations
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TL;DR: A review of nearly a decade of short gamma-ray bursts and their afterglow and host-galaxy observations is presented in this article, where the authors use this information to shed light on the nature and properties of their progenitors, the energy scale and collimation of the relativistic outflow, and the properties of the circumburst environments.
Abstract: Gamma-ray bursts (GRBs) display a bimodal duration distribution with a separation between the short- and long-duration bursts at about 2 s. The progenitors of long GRBs have been identified as massive stars based on their association with Type Ic core-collapse supernovae (SNe), their exclusive location in star-forming galaxies, and their strong correlation with bright UV regions within their host galaxies. Short GRBs have long been suspected on theoretical grounds to arise from compact object binary mergers (neutron star–neutron star or neutron star–black hole). The discovery of short GRB afterglows in 2005 provided the first insight into their energy scale and environments, as well as established a cosmological origin, a mix of host-galaxy types, and an absence of associated SNe. In this review, I summarize nearly a decade of short GRB afterglow and host-galaxy observations and use this information to shed light on the nature and properties of their progenitors, the energy scale and collimation of the relativistic outflow, and the properties of the circumburst environments. The preponderance of the evidence points to compact object binary progenitors, although some open questions remain. On the basis of this association, observations of short GRBs and their afterglows can shed light on the on- and off-axis electromagnetic counterparts of gravitational wave sources from the Advanced LIGO/Virgo experiments.
1,061 citations
Queen Mary University of London1, Spanish National Research Council2, Open University3, Carnegie Institution for Science4, University of Göttingen5, University of Texas at Austin6, University of Chile7, University of Hertfordshire8, University of Warsaw9, Max Planck Society10, University of Montpellier11, Weizmann Institute of Science12, Heidelberg University13
TL;DR: Observations reveal the presence of a small planet with a minimum mass of about 1.3 Earth masses orbiting Proxima with a period of approximately 11.2 days at a semi-major-axis distance of around 0.05 astronomical units.
Abstract: At a distance of 1.295 parsecs, the red dwarf Proxima Centauri (α Centauri C, GL 551, HIP 70890 or simply Proxima) is the Sun's closest stellar neighbour and one of the best-studied low-mass stars. It has an effective temperature of only around 3,050 kelvin, a luminosity of 0.15 per cent of that of the Sun, a measured radius of 14 per cent of the radius of the Sun and a mass of about 12 per cent of the mass of the Sun. Although Proxima is considered a moderately active star, its rotation period is about 83 days (ref. 3) and its quiescent activity levels and X-ray luminosity are comparable to those of the Sun. Here we report observations that reveal the presence of a small planet with a minimum mass of about 1.3 Earth masses orbiting Proxima with a period of approximately 11.2 days at a semi-major-axis distance of around 0.05 astronomical units. Its equilibrium temperature is within the range where water could be liquid on its surface.
1,052 citations
TL;DR: It is observed that the matter wave field of the Bose–Einstein condensate undergoes a periodic series of collapses and revivals; this behaviour is directly demonstrated in the dynamical evolution of the multiple matter wave interference pattern.
Abstract: A Bose–Einstein condensate represents the most ‘classical’ form of a matter wave, just as an optical laser emits the most classical form of an electromagnetic wave. Nevertheless, the matter wave field has a quantized structure owing to the granularity of the discrete underlying atoms. Although such a field is usually assumed to be intrinsically stable (apart from incoherent loss processes), this is no longer true when the condensate is in a coherent superposition of different atom number states1,2,3,4,5,6. For example, in a Bose–Einstein condensate confined by a three-dimensional optical lattice, each potential well can be prepared in a coherent superposition of different atom number states, with constant relative phases between neighbouring lattice sites. It is then natural to ask how the individual matter wave fields and their relative phases evolve. Here we use such a set-up to investigate these questions experimentally, observing that the matter wave field of the Bose–Einstein condensate undergoes a periodic series of collapses and revivals; this behaviour is directly demonstrated in the dynamical evolution of the multiple matter wave interference pattern. We attribute the oscillations to the quantized structure of the matter wave field and the collisions between individual atoms.
980 citations
TL;DR: The authors show the operational environment of asteroid Bennu, validate its photometric phase function and demonstrate the accelerating rotational rate due to YORP effect using the data acquired during the approach phase of OSIRIS-REx mission.
Abstract: During its approach to asteroid (101955) Bennu, NASA’s Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft surveyed Bennu’s immediate environment, photometric properties, and rotation state. Discovery of a dusty environment, a natural satellite, or unexpected asteroid characteristics would have had consequences for the mission’s safety and observation strategy. Here we show that spacecraft observations during this period were highly sensitive to satellites (sub-meter scale) but reveal none, although later navigational images indicate that further investigation is needed. We constrain average dust production in September 2018 from Bennu’s surface to an upper limit of 150 g s–1 averaged over 34 min. Bennu’s disk-integrated photometric phase function validates measurements from the pre-encounter astronomical campaign. We demonstrate that Bennu’s rotation rate is accelerating continuously at 3.63 ± 0.52 × 10–6 degrees day–2, likely due to the Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect, with evolutionary implications.
905 citations