arXiv subjects

Piotr Guzik

Publications and source records attributed to Piotr Guzik.

5 recordsLinked to original sources

arXiv2025

ECOSoundSet: a finely annotated dataset for the automated acoustic identification of Orthoptera and Cicadidae in North, Central and temperate Western Europe

Currently available tools for the automated acoustic recognition of European insects in natural soundscapes are limited in scope. Large and ecologically heterogeneous acoustic datasets are currently needed for these algorithms to cross-contextually recognize the subtle and complex acoustic signatures produced by each species, thus making the availability of such datasets a key requisite for their development. Here we present ECOSoundSet (European Cicadidae and Orthoptera Sound dataSet), a dataset containing 10,653 recordings of 200 orthopteran and 24 cicada species (217 and 26 respective taxa when including subspecies) present in North, Central, and temperate Western Europe (Andorra, Belgium, Denmark, mainland France and Corsica, Germany, Ireland, Luxembourg, Monaco, Netherlands, United Kingdom, Switzerland), collected partly through targeted fieldwork in South France and Catalonia and partly through contributions from various European entomologists. The dataset is composed of a combination of coarsely labeled recordings, for which we can only infer the presence, at some point, of their target species (weak labeling), and finely annotated recordings, for which we know the specific time and frequency range of each insect sound present in the recording (strong labeling). We also provide a train/validation/test split of the strongly labeled recordings, with respective approximate proportions of 0.8, 0.1 and 0.1, in order to facilitate their incorporation in the training and evaluation of deep learning algorithms. This dataset could serve as a meaningful complement to recordings already available online for the training of deep learning algorithms for the acoustic classification of orthopterans and cicadas in North, Central, and temperate Western Europe.

cs.SD↗

arXiv2021

Gaseous atomic nickel in the coma of interstellar comet 2I/Borisov

On 31 August 2019, an interstellar comet was discovered as it passed through the Solar System (2I/Borisov). Based on initial imaging observations, 2I/Borisov appeared to be completely similar to ordinary Solar System comets - an unexpected characteristic after the multiple peculiarities of the only previous known interstellar visitor 1I/'Oumuamua. Spectroscopic investigations of 2I/Borisov identified the familiar cometary emissions from CN, C2, O I, NH2, OH, HCN, and CO, revealing a composition similar to that of carbon monoxide-rich Solar System comets. At temperatures >700 K, comets additionally show metallic vapors produced by the sublimation of metal-rich dust grains. However, due to the high temperature needed, observation of gaseous metals has been limited to bright sunskirting and sungrazing comets and giant star-plunging exocomets. Here we report spectroscopic detection of atomic nickel vapor in the cold coma of 2I/Borisov observed at a heliocentric distance of 2.322 au - equivalent to an equilibrium temperature of 180 K. Nickel in 2I/Borisov seems to originate from a short-lived nickelbearing molecule with a lifetime of $340^{+260}_{-200}$ s at 1 au and is produced at a rate of $0.9 \pm 0.3 \times 10^{22}$ atoms s$^{-1}$, or 0.002% relative to OH and 0.3% relative to CN. The detection of gas-phase nickel in the coma of 2I/Borisov is in line with the concurrent identification of this atom (as well as iron) in the cold comae of Solar System comets.

astro-ph.EP↗

arXiv2019

Initial characterization of interstellar comet 2I/Borisov

Interstellar comets penetrating through the Solar System had been anticipated for decades. The discovery of asteroidal-looking 'Oumuamua was thus a huge surprise and a puzzle. Furthermore, the physical properties of the 'first scout' turned out to be impossible to reconcile with Solar System objects, challenging our view of interstellar minor bodies. Here, we report the identification and early characterization of a new interstellar object, which has an evidently cometary appearance. The body was discovered by Gennady Borisov on 30 August 2019 UT and subsequently identified as hyperbolic by our data mining code in publicly available astrometric data. The initial orbital solution implies a very high hyperbolic excess speed of ~32 km/s, consistent with 'Oumuamua and theoretical predictions. Images taken on 10 and 13 September 2019 UT with the William Herschel Telescope and Gemini North Telescope show an extended coma and a faint, broad tail. We measure a slightly reddish colour with a g'-r' colour index of 0.66 +/- 0.01 mag, compatible with Solar System comets. The observed morphology is also unremarkable and best explained by dust with a power-law size-distribution index of -3.7 +/- 1.8 and a low ejection speed (44 +/- 14 m/s for $β$ = 1 particles, where $β$ is the ratio of the solar gravitational attraction to the solar radiation pressure). The nucleus is probably ~1 km in radius, again a common value among Solar System comets, and has a negligible chance of experiencing rotational disruption. Based on these early characteristics, and putting its hyperbolic orbit aside, 2I/Borisov appears indistinguishable from the native Solar System comets.

astro-ph.EP↗

arXiv2018

The Excited Spin State of 1I/2017 U1 `Oumuamua

We show that `Oumuamua's excited spin could be in a high energy LAM state, which implies that its shape could be far from the highly elongated shape found in previous studies. CLEAN and ANOVA algorithms are used to analyze `Oumuamua's lightcurve using 818 observations over 29.3~days. Two fundamental periodicities are found at frequencies (2.77$\pm$0.11) and (6.42$\pm$0.18)~cycles/day, corresponding to (8.67$\pm$0.34)~h and (3.74$\pm$0.11)~h, respectively. The phased data show that the lightcurve does not repeat in a simple manner, but approximately shows a double minimum at 2.77~cycles/day and a single minimum at 6.42~cycles/day. This is characteristic of an excited spin state. `Oumuamua could be spinning in either the long (LAM) or short (SAM) axis mode. For both, the long axis precesses around the total angular momentum vector with an average period of (8.67$\pm$0.34)~h. For the three LAMs we have found, the possible rotation periods around the long axis are 6.58, 13.15, or 54.48~h, with 54.48~h being the most likely. `Oumuamua may also be nutating with respective periods of half of these values. We have also found two possible SAM states where `Oumuamua oscillates around the long axis with possible periods at 13.15 and 54.48~h, the latter as the most likely. In this case any nutation will occur with the same periods. Determination of the spin state, the amplitude of the nutation, the direction of the TAMV, and the average total spin period may be possible with a direct model fit to the lightcurve. We find that `Oumuamua is "cigar-shaped"', if close to its lowest rotational energy, and an extremely oblate spheroid if close to its highest energy state for its total angular momentum.

astro-ph.EP↗

arXiv2017

Tumbling motion of 1I/'Oumuamua reveals body's violent past

Models of the Solar System evolution show that almost all the primitive material leftover from the formation of the planets was ejected to the interstellar space as a result of dynamical instabilities. Accordingly, minor bodies should also be ejected from other planetary systems and should be abundant in the interstellar space. The number density of such objects, and prospects for their detection as they penetrate through the Solar System, were speculated about for decades, recently rising high hopes with the Pan-STARRS and LSST surveys. These expectations materialized on 18 October 2017 with the Pan-STARRS's discovery of 1I/'Oumuamua. Here we report homogeneous photometric observations of this body from Gemini North, which densely cover a total of 8 hr over two nights. A combined ultra-deep image of 1I/'Oumuamua shows no signs of cometary activity, confirming the results from earlier, less sensitive searches. Our data also show an enormous range of brightness variations > 2.5 mag, larger than ever observed in the population of Solar System objects, suggesting a very elongated shape of the body. But most significantly, the light curve does not repeat exactly from one rotation cycle to another and its double-peaked periodicity of 7.5483 $\pm$ 0.0073 hr from our data is inconsistent with earlier determinations. These are clear signs of a tumbling motion, a remarkable characteristic of 1I/'Oumuamua's rotation, consistent with a catastrophic collision in the distant past. This first example of an impacted minor body of exosolar origin indicates that collisional evolution of minor body populations in other planetary systems is not uncommon.

astro-ph.EP↗