240 research outputs found

    Growing up with nature photography

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    I took up nature photography at a very young age. I embarked on this path first to satisfy the need to slow down and, somehow, stop the constant flow of emotions and experiences lived observing animals and exploring natural environments since my childhood. The images I took then offered me the opportunity to store those emotions forever, to relive them from time to time and to be even able to share them with others. In addition, I began to like the slow pace required by the photographic technique, which imposed patience, attention, empathy. A discipline that, compared to mere contemplation, urged me to look at things more in depth, teaching me to appreciate the constant variations of light, to look at animals in the eyes and to identify form and patterns in the apparent chaos that surrounds us. On the other hand, in the fleeting moment when you take a photograph, what is framed in the viewfinder becomes the most important thing in the world. This forced slowness then turned into a kind of initiation to the secrets of the subjects at the center of my photographic research. A very personal cultural journey that greatly increased my knowledge of nature things and gradually also the sense of belonging to something greater. With this baggage of awareness, I quickly went from a purely documentary photography to a more representative and, in some way, introspective one. What began as a moment of aesthetic contemplation soon became an inner dialogue, between the self and the world, regardless of the object or location. Even portraying a small insect, in fact, you notice your own image reflected in its eyes. Once I finished my university studies and with a degree in Biological Sciences in the bag, I chose to abandon a possible scientific career and instead undertake the profession of nature photographer. This is because, compared to the rigour and the greater depth required by scientific research, photography granted me instead the freedom to span between different topics, get to know very different realities and enter a deeper communication with the subjects of my work. It was then that, in order to overcome the apparent superficiality of the photographic approach and also to be able to build up a more robust professional portfolio, I chose to work exclusively on projects and not to seek the sensationalism of a single shot. Since then, all my photographic work has been carried out solely as a result of thorough research and meticulous planning and with a long-term approach. This allowed me eventually to turn the photo shoot into a research and the subsequent sharing of images into a process of dissemination and education. In this way, I discovered the fundamental role that photography can play in the conversation on our relationship with nature and in supporting the battle for the conservation of species and natural habitats. On the other hand, photography is a universal and very powerful language, that allows to overcome cultural, geographical and age barriers. Images can convey messages, arouse emotions and, therefore, become a useful communication tool to increase people's awareness toward certain issues. Despite the common perception, photography is not truth but can become "true" exclusively in the intentions of the photographer. It is at the end of the path taken by the photographer, in the honesty of this person, in the ethical sense and in the empathy with which she approaches her subjects that a photographic work can become truthful. Only a respectful and sincere photograph, both with regard to the well-being of the subject and the correctness of the message, can become a mirror of reality. I chose to share this personal experience with photography with fellow scientific researchers during the seminar “In Cammino al tempo dell'ecologia” organised by the LTER network at Feudozzo in 2019, in order to possibly offer a different perspective on ecology and invite them to use photography as a tool for discovery and education

    Geoeffectiveness and efficiency of CIR, Sheath and ICME in generation of magnetic storms

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    We investigate relative role of various types of solar wind streams in generation of magnetic storms. On the basis of the OMNI data of interplanetary measurements for the period of 1976-2000 we analyze 798 geomagnetic storms with Dst < -50 nT and their interplanetary sources: corotating interaction regions (CIR), interplanetary CME (ICME) including magnetic clouds (MC) and Ejecta and compression regions Sheath before both types of ICME. For various types of solar wind we study following relative characteristics: occurrence rate; mass, momentum, energy and magnetic fluxes; probability of generation of magnetic storm (geoeffectiveness) and efficiency of process of this generation. Obtained results show that despite magnetic clouds have lower occurrence rate and lower efficiency than CIR and Sheath they play an essential role in generation of magnetic storms due to higher geoeffectiveness of storm generation (i.e higher probability to contain large and long-term southward IMF Bz component).Comment: 23 pages, 4 figures, 3 tables, submitted to JGR special issue "Response of Geospace to High-Speed Streams

    Simultaneous MITSuME gRI monitoring of S5 0716+714

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    We present results of our intra-night optical flux monitoring observations of S5 0716+714 done simultaneously in gRI filters. The observations were done using Multicolor Imaging Telescopes for Survey and Monstrous Explosions (MITSuME) instrument on the 50 cm telescope at the Okayama Astrophysical Observatory over 30 nights between 11 March 2008 and 8 May 2008. Of these 30 nights, 22 nights have continuous (without any break) observations with duration ranging from 1 to 6 hours and hence were considered for intra-night optical variability (INOV). In total we have 4888 datapoints which were simultaneous in gR and I filters. Of the 22 nights considered for INOV, the object showed flux variability on 19 nights with the amplitude of variability in the I-band ranging from ~4% to ~55%. The duty cycle for INOV was thus found to be 83%. No time lag between different bands was noticed on most of the nights, except for 3 nights where the variation in g was found to lead that of the I band by 0.3 to 1.5 hrs. On inter-night timescales, no lag was found between g and I bands. On inter-night timescales as well as intra-night timescales on most of the nights, the amplitude of variability was found to increase toward shorter wavelengths. The flux variations in the different bands were not achromatic, with the blazar tending to become bluer when brighter both on inter-night and intra-night timescales; and this might be attributed to the larger amplitude variation at shorter wavelengths. A clear periodic variation of 3.3 hrs was found on 1 April 2008 and a hint for another possible periodic variability of 4 hrs was found on 31 March 2008. During our 30 days of observations over a 2 month period the source has varied with an amplitude of variability as large as ~80%.Comment: 11 pages, 8 figures and 5 tables, Accepted in MNRA

    The BL Lac objects OQ 530 and S5 0716+714. Simultaneous observations in the X-rays, radio, optical and TeV bands

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    We present the results of the BeppoSAX observations of two BL Lacs, OQ 530 and S5 0716+714, as part of a ToO program for the simultaneous observation at radio, optical, X-ray and TeV energies. Both sources are detected in the LECS and MECS, with S5 0716+714 visible also in the PDS band, up to about 60 keV. The X-ray spectra of both sources are better fitted by a double power-law model, with a steep soft X-ray component flattening at harder energies, with breaks at 0.3 and 1.5 keV, respectively. The concave shape of the spectra in both objects is consistent with soft X-rays being produced by the synchrotron and harder X-rays by the inverse Compton processes. Also the X-ray variability properties confirm this scenario, in particular for S5 0716+714 our observation shows variations by about a factor 3 over one hour below 3 keV and no variability above. Their simultaneous broad band energy spectral distributions can be successfully interpreted within the frame of a homogeneous synchrotron and inverse Compton model, including a possible contribution from an external source of seed photons with the different spectral states of S5 0716+714 being reproduced by changing the injected power. The resulting parameters are fully consistent with the two sources being intermediate objects within the "sequence" scenario proposed for blazars.Comment: 10 pages, 8 figures, accepted by A&

    Solar cycle variation of the statistical distribution of the solar wind ε parameter and its constituent variables

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    We use 20 years of Wind solar wind observations to investigate the solar cycle variation of the solar wind driving of the magnetosphere. For the first time, we use generalized quantile-quantile plots to compare the statistical distribution of four commonly used solar wind coupling parameters, Poynting flux, B 2, the ε parameter, and vB ,between the maxima and minima of solar cycles 23 and 24. We find the distribution is multicomponent and has the same functional form at all solar cycle phases; the change in distribution is captured by a simple transformation of variables for each component. The ε parameter is less sensitive than its constituent variables to changes in the distribution of extreme values between successive solar maxima. The quiet minimum of cycle 23 manifests only in lower extreme values, while cycle 24 was less active across the full distribution range

    Multi-colour optical monitoring of eight red blazars

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    We present the observational results of multi-colour optical monitoring of eight red blazars from 2003 September to 2004 February. The aim of our monitoring is to investigate the spectral variability as well as the flux variations at short and long time scales. The observations were carried out using the 1.0 m robotic telescope of Mt. Lemmon Optical Astronomy Observatory, in Arizona, USA, the 0.6 m telescope of Sobaeksan Optical Astronomy Observatory and the 1.8 m telescope of Bohyunsan Optical Astronomy Observatory, in the Republic of Korea. During the observations, all sources show strong flux variations with amplitudes of larger than 0.5 mag. Variations with amplitudes of over 1 mag are found in four sources. Intraday variations with amplitudes larger than 0.15 mag, and a rapid brightness increase with a rate of ~0.2 mag per day in four days, are detected in S5 0716+71. We investigate the relationship between the colour index and source brightness for each source. We find that two out of three FSRQs tend to be redder when they are brighter, and, conversely, all BL Lac objects tend to be bluer. In particular, we find a significant anti-correlation between the V-I colour index and R magnitude for 3C 454.3. This implies that the spectrum became steeper when the source was brighter, which is opposite to the common trend for blazars. In contrast, significant positive correlations are found in 3C 66A, S5 0716+71, and BL Lac. However, there are only very weak correlations for PKS 0735+17 and OJ 287. We propose that the different relative contributions of the thermal versus non-thermal radiation to the optical emission may be responsible for the different trends of the colour index with brightness in FSRQs and BL Lac objects.Comment: 15 pages, 12 figures. Accepted for publication in A&

    Observations of IMF coherent structures and their relationship to SEP dropout events

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    Abstract. The solar energetic particle (SEP) events from impulsive solar flares are often characterized by short-timescale modulations affecting, at the same time, particles with different energies. Several models and simulations suggest that these modulations are observed when SEPs propagate through magnetic structures with a different connection with the flare site. However, in situ observations rarely showed clear magnetic signatures associated with these modulations. In this paper we used the Grad–Shafranov reconstruction to perform a detailed analysis of the local magnetic field topology during the SEP event of 9–10 January 1999, characterized by several SEP dropouts. An optimization procedure is used to identify, during this SEP event, the magnetic structures which better satisfy the Grad–Shafranov assumptions and to evaluate the direction of their invariant axis. We found that these two-dimensional structures, which are flux ropes or current sheets with a more complex field topology, are generally associated with the maxima in the SEP counts. This association suggests that the SEPs propagate within these structures and, since their gyration radii is much smaller than the transverse dimension of these structure, cannot escape from them

    On the Origin of Highly Alfvénic Slow Solar Wind

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    Alfvénic fluctuations are a common feature in the solar wind and are found especially in the trailing edges of fast wind streams. The slow wind usually has a lower degree of Alfvénicity, being more strongly intermixed with structures of non-Alfvénic nature. In the present paper we show the first evidence in the interplanetary space of two different kinds of slow solar wind: one coming from coronal streamers or active regions and characterized by non-Alfvénic structures and the other one being highly Alfvénic and originating from the boundary of coronal holes. The Alfvénic character of fluctuations, either outward or inward, can be studied by means of the normalized cross-helicity, {{σ }C}, which is an indicator of the {\boldsymbol{v}} -{\boldsymbol{b}} alignment. The evolution of {{σ }C} toward lower values with increasing radial distance is interpreted both as a decrease of the presence of the outward modes and as a continuous production of inward modes within those regions such as stream shears where some plasma instability is active. On the other hand, the decrease of {{σ }C} is often related also to magnetic field and/or density enhancements which specifically act on the destruction of the {\boldsymbol{v}} -{\boldsymbol{b}} alignment. In the present analysis we study the role of compressibility presenting both case studies and a statistical analysis over different phases of solar cycle 23. Our findings indicate that the presence of regions of magnetic field compression generally play a major role in the depletion of {{σ }C} and thus in the destruction of the {\boldsymbol{v}} -{\boldsymbol{b}} alignment
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