FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W3182194902> ?p ?o ?g. }

• W3182194902 abstract "The central parsec is one of the most interesting regions of our Galaxy. It is populated by a nuclear stellar cluster where massive, energetic and young stars coexist with colder evolved stars, hot plasma and streams of interstellar matter. A compact object called SgrA* with a mass of several million solar masses lies in its center becoming the closest supermassive black hole candidate, but being fainter in all wavelengths than other galactic nuclei. One of the closest stars to SgrA*, S2, completes an orbit around it in just 16 years and is bright enough to be used as a robust probe the gravitational potential of the central source by orbit tracking. In the infrared, SgrA* presents a quiescent emission with random short episodes called flares where its brightness sharply increases up to a factor 4, lasting several hours before dimming. The origin of these flares is likely due to the presence of accretion processes in the close environment of the black hole and their study can provide essential information about the exotic nature of SgrA*. Unfortunately, these events are random and require a sufficiently sampled monitoring over time.The GRAVITY instrument, part of the second generation of VLTI, enables the use of optical interferometry to study the Galactic Center. It is able to track the orbit of the star S2 with unprecedented accuracy, up to 10 micro-arcseconds. This thesis work is focused on the data analysis of the first products of the GRAVITY instrument in the Galactic Center.In the first part of the thesis, the astrometry of the star S2 is obtained by the use of the first two years of GRAVITY observations, in which I have actively participated. For that purpose, abinary star model is used to reproduce the interferometric data. Right before and after the pericenter passage, who took place in 2018, I have obtained the positions of S2 with respect to SgrA* reaching an astrometric accuracy of 30 micro-arcseconds, comparable with the expected size of the shadow of the supermassive black hole. In addition, I have obtained a new light curve of SgrA* which complements the data already published and confirms the quiescent-flare scenario. The results obtained are part of a larger study involving orbit fitting where several tests of General Relativity have been successfully performed, as well as interpretations of the flares as a product of accretion processes in the near SgrA* orbit.The second part of the thesis is focused on an evolved star called GCIRS 7, which is also located in the central parsec and serves as a reference for GRAVITY observations. This star, which has a large variability in the infrared, is known to contribute to the interstellar medium of the Galactic Center. By complementing GRAVITY archival data from 2017 with observations I have taken in 2019, I have implemented an atmosphere model, widely used for the study of other advanced stars, to explain the visibility curves of GCIRS 7 obtained by GRAVITY. The model consists of a photosphere and a thin molecular shell. The results show that the data can be interpreted as a photosphere with the same diameter for both epochs, but with a shell being colder and larger in 2019 compared to 2017. An estimation of the density of the thin shell reveals a saturation of the model for 2017 due to a high density, but 2019 data is partially reproduced. The results can be explained by a layer expansion and cooling likely due to an episode of mass loss." @default.
• W3182194902 created "2021-07-19" @default.
• W3182194902 creator A5049999845 @default.
• W3182194902 date "2020-11-30" @default.
• W3182194902 modified "2023-09-27" @default.
• W3182194902 title "Exploring the supermassive black hole Sgr A* at the Galactic Center with astrometry of flares" @default.
• W3182194902 hasPublicationYear "2020" @default.
• W3182194902 type Work @default.
• W3182194902 sameAs 3182194902 @default.
• W3182194902 citedByCount "0" @default.
• W3182194902 crossrefType "dissertation" @default.
• W3182194902 hasAuthorship W3182194902A5049999845 @default.
• W3182194902 hasConcept C104954878 @default.
• W3182194902 hasConcept C105500671 @default.
• W3182194902 hasConcept C121332964 @default.
• W3182194902 hasConcept C1276947 @default.
• W3182194902 hasConcept C132552067 @default.
• W3182194902 hasConcept C150846664 @default.
• W3182194902 hasConcept C173120059 @default.
• W3182194902 hasConcept C18609725 @default.
• W3182194902 hasConcept C190330329 @default.
• W3182194902 hasConcept C2778952920 @default.
• W3182194902 hasConcept C31258907 @default.
• W3182194902 hasConcept C32602459 @default.
• W3182194902 hasConcept C41008148 @default.
• W3182194902 hasConcept C43481613 @default.
• W3182194902 hasConcept C44870925 @default.
• W3182194902 hasConcept C50341732 @default.
• W3182194902 hasConcept C74172769 @default.
• W3182194902 hasConcept C89305328 @default.
• W3182194902 hasConcept C98444146 @default.
• W3182194902 hasConceptScore W3182194902C104954878 @default.
• W3182194902 hasConceptScore W3182194902C105500671 @default.
• W3182194902 hasConceptScore W3182194902C121332964 @default.
• W3182194902 hasConceptScore W3182194902C1276947 @default.
• W3182194902 hasConceptScore W3182194902C132552067 @default.
• W3182194902 hasConceptScore W3182194902C150846664 @default.
• W3182194902 hasConceptScore W3182194902C173120059 @default.
• W3182194902 hasConceptScore W3182194902C18609725 @default.
• W3182194902 hasConceptScore W3182194902C190330329 @default.
• W3182194902 hasConceptScore W3182194902C2778952920 @default.
• W3182194902 hasConceptScore W3182194902C31258907 @default.
• W3182194902 hasConceptScore W3182194902C32602459 @default.
• W3182194902 hasConceptScore W3182194902C41008148 @default.
• W3182194902 hasConceptScore W3182194902C43481613 @default.
• W3182194902 hasConceptScore W3182194902C44870925 @default.
• W3182194902 hasConceptScore W3182194902C50341732 @default.
• W3182194902 hasConceptScore W3182194902C74172769 @default.
• W3182194902 hasConceptScore W3182194902C89305328 @default.
• W3182194902 hasConceptScore W3182194902C98444146 @default.
• W3182194902 hasLocation W31821949021 @default.
• W3182194902 hasOpenAccess W3182194902 @default.
• W3182194902 hasPrimaryLocation W31821949021 @default.
• W3182194902 hasRelatedWork W1651593697 @default.
• W3182194902 hasRelatedWork W1894883222 @default.
• W3182194902 hasRelatedWork W2008600579 @default.
• W3182194902 hasRelatedWork W2030776989 @default.
• W3182194902 hasRelatedWork W2031106768 @default.
• W3182194902 hasRelatedWork W2049374454 @default.
• W3182194902 hasRelatedWork W2094689709 @default.
• W3182194902 hasRelatedWork W2109737215 @default.
• W3182194902 hasRelatedWork W2779016419 @default.
• W3182194902 hasRelatedWork W2807453391 @default.
• W3182194902 hasRelatedWork W2936349953 @default.
• W3182194902 hasRelatedWork W2986001559 @default.
• W3182194902 hasRelatedWork W3100372210 @default.
• W3182194902 hasRelatedWork W3100487131 @default.
• W3182194902 hasRelatedWork W3103090356 @default.
• W3182194902 hasRelatedWork W3113329333 @default.
• W3182194902 hasRelatedWork W3122494504 @default.
• W3182194902 hasRelatedWork W3123927616 @default.
• W3182194902 hasRelatedWork W3124154380 @default.
• W3182194902 hasRelatedWork W2141852208 @default.
• W3182194902 isParatext "false" @default.
• W3182194902 isRetracted "false" @default.
• W3182194902 magId "3182194902" @default.
• W3182194902 workType "dissertation" @default.