1,731,145 research outputs found
Analisi spettroscopica della prima cometa interstellare 2I/Borisov
No full textLa scoperta del passaggio di oggetti interstellari attraverso il Sistema
Solare ci permette di poter studiare processi chimici e fisici in corpi sconosciuti. Lo studio di questi corpi permette anche di investigare le condizioni di formazione
nel loro luogo d'origine e di formulare ipotesi sui processi che hanno portato alla loro dispersione nel mezzo interstellare. 2I/Borisov è la prima cometa interstellare
ad essere stata osservata. Scoperta il 30 Agosto 2019 da Gennady Borisov, questa cometa è già stata oggetto di numerosi studi che ne hanno delineato delle prime proprietà. Lo scopo di
questa tesi è quello d fornire un'analisi spettroscopica preliminaredi 2I/Borisov e di sperimentare alcune tecniche di riduzione degli spettri. Nel capitolo 1 vengono descritte le proprietà fisiche e chimiche finora conosciute delle comete appartenenti al Sistema Solare. Vengono descritte anche le varie classificazioni dinamiche. Nel capitolo 2 si riassumono le principali scoperte sulla cometa interstellare 2I/Borisov, già pubblicate in numerosi articoli. Nel terzo capitolo si descrivono i passaggi effettuati nell'analisi spettroscopica che portano ad una discussione finale dei risultati.ope
The class of the affine line is a zero divisor in the Grothendieck ring
No full textWe show that the class of the affine line is a zero divisor in the Grothendieck ring of algebraic varieties over complex numbers. The argument is based on the Pfaffian-Grassmannian double mirror correspondence.Peer reviewe
Unusual polarimetric properties for interstellar comet 2I/Borisov
No full textSo far, only two interstellar objects have been observed within our Solar System. While the first one, 1I/‘Oumuamua, had asteroidal characteristics, the second one, 2I/Borisov, showed clear evidence of cometary activity. We performed polarimetric observations of comet 2I/Borisov using the European Southern Observatory Very Large Telescope to derive the physical characteristics of its coma dust particles. Here we show that the polarization of 2I/Borisov is higher than what is typically measured for Solar System comets. This feature distinguishes 2I/Borisov from dynamically evolved objects such as Jupiter-family and all short- and long-period comets in our Solar System. The only object with similar polarimetric properties as 2I/Borisov is comet C/1995 O1 (Hale-Bopp), an object that is believed to have approached the Sun only once before its apparition in 1997. Unlike Hale-Bopp and many other comets, though, comet 2I/Borisov shows a polarimetrically homogeneous coma, suggesting that it is an even more pristine object.This work is based on observations made with ESO Telescopes at the La Silla Paranal Observatory thanks to Director Discretionary Time under programme ID 2104.C-5003. The work of T.S.-R. was carried out through grant APOSTD/2019/046 by Generalitat Valenciana (Spain). This work was supported by the MINECO (Spanish Ministry of Economy) through grant RTI2018-095076-B-C21 (MINECO/FEDER, UE)
A JOURNEY FROM THE OCTONIONIC P2 TO A FAKE P2
No full textWe discover a family of surfaces of general type with K2 = 3 and pg = q = 0 as free C13 quotients of special linear cuts of the octonionic projective plane OP2. A special member of the family has 3 singularities of type A2, and is a quotient of a fake projective plane. We use the techniques of earlier work of Borisov and Fatighenti to define this fake projective plane by explicit equations in its bicanonical embedding
A journey from the octonionic P2 to a fake P2
No full textWe discover a family of surfaces of general type with K2=3
and pg=q=0 as free C13 quotients of special linear cuts of the octonionic projective plane OP2. A special member of the family has
3 singularities of type A2, and is a quotient of a fake projective plane. We use the techniques of earlier work of Borisov and Fatighenti to define this fake projective plane by explicit equations in its bicanonical embedding
Professor Aleksandr Evgenevich Borisov (on the 70th anniversary of the birth).
No full textAlexander Evgenievich Borisov – head of the Department of surgery named after N. D. Monastyrskii (Available at: https://www.livelib.ru/author/733938/series-aleksandr-borisov
Kurven und Flächen im dreidimensionalen Raum mit Absolutem, das aus zwei reellen Ebenen und zwei reellen Punkten ihrer gemeinsamen Geraden besteht
No full text[Borisov Adrian; Borisov A.; Borisov Adrijan V.; Borisov Adriyan V.; Borisov Andriyan; Борисов Адриян]Bulgarian. Russian, German summar
О конгруэнциях прямых в трехмерном пространстве с абсолютом двумя реальными точками и одной реальной плоскостью, проходящей через одну из них
No full text[Borisov Adrian; Borisov A.; Borisov Adrijan V.; Borisov Adriyan V.; Borisov Andriyan; Борисов Адриян]Bulgarian. Russian, English summar
Cometary observations in light-polluted environments: a case study of interstellar comet 2I/Borisov
No full textComets and asteroids have long captured human curiosity, and until recently, all documented examples belonged to our Solar System. That changed with the discovery of the first known interstellar object, 1I/2017 U1 (‘Oumuamua), in 2017. Two years later, on August 30, 2019, Gennady Borisov discovered a second interstellar object, 2019 Q4, which was officially designated 2I/Borisov. From its initial images, the object’s diffuse appearance hinted at its cometary nature. To better understand the photometric evolution of comet 2I/Borisov as it traveled through the inner Solar System, we compiled observations using medium-sized telescopes. This data is crucial for gaining insights into its size and composition, as well as how such objects, after millions of years in interstellar space, behave when exposed to the Sun’s radiation. Given that 2I/Borisov is the first interstellar comet ever observed, constraining its behavior is of great scientific interest. In this paper, we present photometric data gathered from observatories in Crimea and Catalonia, highlighting the importance of systematic photometric studies of interstellar objects using meter-class telescopes. Our observations showed a steady increase in the comet’s brightness as it approached perihelion, likely due to the slow sublimation of ices. Over the five-month pre-perihelion observation period, we did not detect any significant changes in magnitude. The analysis of observations reveals a steady increase in comet 2I/Borisov brightness as it approached perihelion, likely due to the sublimation of ices, with no observable outbursts during the five-month pre-perihelion period. Additionally, we discuss the challenges in ground-based observation of comets posed by light pollution today, particularly in urban areas, where visual observations are severely limited. Using sample surface brightness measurements, we demonstrate the impact of light pollution and outline the importance of systematic photometric studies for interstellar objects.We acknowledge support from the Spanish Ministry of Science and Innovation, research projects PGC2018-097374-B-I00 and PID2021-128062NB-I00 (PI: JMTR), funded by FEDER/Ministerio de Ciencia e Innovación – Agencia Estatal de Investigación, the Academy of Finland project no. 325806 “PlanetS” (PI: MG), and the Centre for Innovation and Transfer of Natural Sciences and Engineering Knowledge, University of Rzeszów, Poland (RPPK.01.03.00-18-001/10-00). The programme of development within Priority-2030 is acknowledged for supporting the research at UrFU. We thank Herbert Raab for his kind support with Astrometrica software. We also thank the feedback received from A. Fraser Gillan. TJO images at OAdM were scheduled by Toni Santana (UB).Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.Peer reviewe
Geradenkongruenzen im dreidimensionalen Raum, dessen absolutes Gebilde aus zwei reellen Ebenen und zwei reellen Punkten auf deren Schnittlinie besteht
No full text[Borisov Adrian V.; Borisov A.; Borisov Adrijan V.; Borisov Adriyan V.; Borisov Andriyan; Борисов Адриян В.]Bulgarian. Russian, German summar
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