Calendar
Speaker: F. Mirabello (INAF)
Titolo: Il Cerchio di Ramsden, un prodigio tecnologico
Abstract: IL CERCHIO DI RAMSDEN, UN PRODIGIO TECNOLOGICO
Più di 30 anni fa, Paolo Brenni (1954-2021), esperto di strumentazione scientifica di fama internazionale, si recava a Palermo presso l’Osservatorio Astronomico “G. S. Vaiana” per valutare lo stato conservativo del più importante strumento storico dell’Osservatorio, il cerchio astronomico altazimutale realizzato dal costruttore londinese Jesse Ramsden (1735-1800), e gestirne la spedizione a Firenze per un intervento di restauro presso la Fondazione Scienza e Tecnica. Il relatore ha avuto l’onore di collaborare con Brenni in quella circostanza e con questo articolo vuole rendergli un meritato tributo. Presso la Fondazione fiorentina, sotto la supervisione di Brenni, lo strumento fu smontato e ogni parte revisionata e pulita, preservando, ove presente, la lacca protettiva originaria. I due cerchi che costituiscono le parti più complesse dello strumento, ovvero il grande cerchio verticale e il cerchio orizzontale, non furono disassemblati: Brenni, infatti, non ritenne necessario effettuare questo tipo di intervento, sostenendo che scomporre un manufatto assemblato con grande lavoro di aggiustaggio manuale potesse provocare danni irreversibili allo strumento. Nel 1992, lo strumento, tornato a Palermo, fu collocato nella sua sede originaria presso l’Osservatorio Astronomico.
Con questo strumento, padre Giuseppe Piazzi (1746-1826), fondatore e primo direttore dell’Osservatorio Astronomico di Palermo, scoprì nel 1801 il primo asteroide, Cerere Ferdinandea, e svolse le osservazioni per le due edizioni del suo famoso catalogo stellare (pubblicate nel 1803 e nel 1814). Piazzi considerava il cerchio di Ramsden un capolavoro della tecnica. Ancora oggi, dopo più di due secoli, il talento di un costruttore come Ramsden stupisce chiunque. Egli seppe infatti realizzare, con gli strumenti dell’epoca, uno strumento genialmente progettato, inserendo un telescopio in una scala circolare per ottenere una maggiore precisione nelle misurazioni della posizione delle stelle.
In questo seminario verranno presentati dettagli inediti relativi alla tecnica costruttiva, soluzioni che ancora oggi, a distanza di secoli, squarciano l’alone del tempo e rivelano la genialità di Ramsden. Considerando le conoscenze tecnologiche dell’epoca, la sua costruzione fu davvero impegnativa (Ramsden stesso la definì “titanica”).
Interpretando gli indizi presenti sul Cerchio e ripercorrendo la storia della tecnologia del XVIII secolo con i suoi illustri protagonisti, verranno presentati i risultati di un lungo (e ancora non concluso) studio, frutto di ricerche, passione e competenze tecniche del relatore, che cerca di chiarire come Ramsden sia riuscito nella costruzione di uno strumento unico nel suo genere e che ha fornito importanti contributi allo sviluppo dell’astronomia.
Speaker: Manami Sasaki (Universita’ di Bamberg – Germania)
Titolo: The hot phase of the interstellar medium
Abstract:
The interstellar medium (ISM) is heated and ionized by radiation, by stellar winds, and finally, by supernova explosions of massive stars. Since these processes are often correlated in space and time, they can form large interstellar structures called superbubbles, which are filled with hot thin plasma. Supernova remnants and superbubbles can be studied best in X-rays since the plasma in their interiors is very hot (10^6 − 10^7 K), while particles are also accelerated in the shock waves. I will present recent results of studies of the hot phase of the ISM in the Milky Way and nearby galaxies, in particular in the Magellanic Clouds, and discuss the physics of the hot plasma, the evolution and energetics of supernova remnants and superbubbles, and the implications for the star formation history of the galaxies.
SHARP – A Near-IR Multi-mode Spectrograph Conceived for the Multi-Conjugate Adaptive Optics Module MORFEO@ELT
Abstract:
The world’s largest aperture combined with state-of-the-art Adaptive Optics systems will enable the ELT to capture better data than the JWST in both sharpness and depth. Therefore, the spectrograph intended for the 2nd port of the Multi-Conjugate Adaptive Optics (MCAO) system MORFEO@ELT will be the most powerful instrument of the JWST era, revealing phenomena beyond the reach of others. SHARP (http://sharp.brera.inaf.it) is a near-IR spectrograph designed for the 2nd port of MORFEO@ELT, intended to be submitted in the upcoming ESO instrument call. Composed of a Multi-Object Spectrograph, NEXUS, and a multi-Integral Field Unit, VESPER, SHARP covers the wavelength range to 0.95-2.45 μ. Coupled with MCAO-assisted observations, it delivers unprecedented high angular (~30 mas) and spectral resolution, outperforming NIRSpec@JWST (100 mas). MORFEO-SHARP will allow us to study the nearby and the early Universe in unprecedented detail, resolving the first galaxies and the star forming regions within galaxies far back in cosmic time, and providing spectra of individual nearby young stellar objects. This presentation introduces the scientific rationale behind SHARP, showcasing its features and inviting those interested to join the SHARP team.
Ref. Miceli 40 pax
Speaker: Salvatore Sciortino (INAF)
Titolo: ” `Time` and Physics: A strange marriage and more …”
Abstract:
The physical nature of Space and Time has been always at the core of the
physical theories. After General Relativity and Quantum Mechanics have become
consolidated main-stream theories some of the attempts to reconcile them have
required to consider a world where Space have more than 3 dimensions, like in
the string theories, or Time is not fundamental, like in the some proposed GR
reformulations, or in the Loop Quantum Gravity, or Space and Time are not
fundamental, like seems to imply the Twistor theory. Following L. Smoolin
analysis and arguments I will discuss why one arrives to the conclusion
(contrary to rooted and somehow hidden ideas) that Time is fundamental and
illustrates some of the key implications on our effort to understand the
physical world, and the conceptual difficulty to apply “standard” physical
theory to the Universe.
Speaker: Salvatore Sciortino (INAF)
Titolo: “Is Quantum Mechanics the last word ? Why not ? Some alternative ideas toward (re-)introducing realism in Physics”
Abstract:
The General Relativity (GR) and Quantum Mechanics (QM) are the two pillars of
today Physics. They have been verified in a huge number of conditions and have
survived to all falsification attempts. Several key aspects of our life and our
societies are based on them, among them the entire internet “world”, mobile
phones and GPS assisted navigation. Despite these astonishing successes, after
about 100 years of efforts of the smartest worldwide physicists GR and QM still
remain essentially incompatible. Most of the past “merging” efforts have mostly
concentrated on attempts to “quantize” general relativity but they have been so
far either unsuccessful or have ended up to unfalsifiable theories. This has
stimulated a critical rethinking of the basis of today physics pillar theories,
especially of QM. I will present some of this alternative ideas, their pro and
con following the analysis path championed by R. Penrose and L. Smoolin whose
ultimate aim is to build a new physical theory based on the idea that a real
world exists (independently from one of us watching it) and Physics is the
science to understand how it really works.
Titolo X-exoplanets and the quest for the He I 10830 triplet in exoplanets
Abstract
Exoplanet atmospheres photoevaporate because of XUV stellar irradiation.
Evaporation signs are mainly detected through the h Lyman-alpha line, or
more recently in the He I 10830 triplet. Despite of early efforts back
in 2000, it was not until 2018 that the line was detected in exoplanet
atmospheres. The He I line is not affected by interstellar medium
absorption, and that is pushing a number of observations to search for
its presence in exoplanet atmospheres. The stellar high energy
irradiation also plays a role in this line formation. But all the
attempts to relate the stellar XUV irradiation and the presence of the
line in exoplanets have ended in just a suggestive trend. Studies
related to photoevaporation, and also on the He I 10830 line, show the
importance of having good models of the XUV stellar emission. Along this
talk I will describe the update done to our early X-exoplanet models,
and how this accurate work has allowed us to define a clear correlation
between XUV stellar irradiation and the detection of He I 10830 triplet
in exoplanet atmospheres. Some hints on the future development of XUV
modelling will be discussed.