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PRODID:-//Osservatorio Astronomico di Roma - ECPv6.15.19//NONSGML v1.0//EN
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X-WR-CALNAME:Osservatorio Astronomico di Roma
X-ORIGINAL-URL:https://www.oa-roma.inaf.it
X-WR-CALDESC:Eventi per Osservatorio Astronomico di Roma
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BEGIN:VTIMEZONE
TZID:Europe/Rome
BEGIN:DAYLIGHT
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
TZNAME:CEST
DTSTART:20170326T010000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:20171029T010000
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BEGIN:DAYLIGHT
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
TZNAME:CEST
DTSTART:20180325T010000
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BEGIN:STANDARD
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:20181028T010000
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TZOFFSETFROM:+0100
TZOFFSETTO:+0200
TZNAME:CEST
DTSTART:20190331T010000
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TZOFFSETFROM:+0200
TZOFFSETTO:+0100
TZNAME:CET
DTSTART:20191027T010000
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BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20180109T114500
DTEND;TZID=Europe/Rome:20180109T124500
DTSTAMP:20260408T141507
CREATED:20170728T202118Z
LAST-MODIFIED:20170728T202118Z
UID:3362-1515498300-1515501900@www.oa-roma.inaf.it
SUMMARY:Microlensing
DESCRIPTION:I will review the microlensing and pixel lensing techniques and show how they play a\nfundamental role in the searches for galactic dark matter\, in the study of the galactic structure and in\ndetecting planets around faint stars whose cahacteristics are in general not accessible to other methods.\nWe show that dedicated and well planned experiments would even allow to detect more exotic objects\nas primordial massive black holes (if any) in nearby galaxies and/or to put strong constraints on\ntheir existence.
URL:https://www.oa-roma.inaf.it/event/seminar-by-raffaella-margutti/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20180109T114500
DTEND;TZID=Europe/Rome:20180109T124500
DTSTAMP:20260408T141507
CREATED:20170728T202118Z
LAST-MODIFIED:20170728T202118Z
UID:4718-1515498300-1515501900@www.oa-roma.inaf.it
SUMMARY:Microlensing
DESCRIPTION:I will review the microlensing and pixel lensing techniques and show how they play a\nfundamental role in the searches for galactic dark matter\, in the study of the galactic structure and in\ndetecting planets around faint stars whose cahacteristics are in general not accessible to other methods.\nWe show that dedicated and well planned experiments would even allow to detect more exotic objects\nas primordial massive black holes (if any) in nearby galaxies and/or to put strong constraints on\ntheir existence.
URL:https://www.oa-roma.inaf.it/event/seminar-by-raffaella-margutti-2/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20180112T114500
DTEND;TZID=Europe/Rome:20180112T124500
DTSTAMP:20260408T141507
CREATED:20171215T072607Z
LAST-MODIFIED:20171215T072607Z
UID:3845-1515757500-1515761100@www.oa-roma.inaf.it
SUMMARY:Not all stars are the Sun: rethinking the Mixing Length
DESCRIPTION:Characterizing heat transport in stars is notoriously complicated\, and the task of reproducing the physics involved with high precision on stellar evolutionary timescales is a long-standing problem in stellar modeling. For this reason\, convection in 1-D stellar evolution codes is addressed primarily through a framework known as mixing length theory (MLT). In this simplified picture\, the efficiency of convective heat transport is encapsulated by the mixing length parameter alpha_{MLT}\, measured in pressure scale heights.\nWhile it is well understood that our nearest star is not a valid representation of stars in general\, it remains the standard procedure to calibrate alpha_{MLT} according to solar specifications\, and then to apply this value in any stellar model\, regardless of mass or composition. However\, there has been growing evidence that the use of a solar-calibrated mixing length is not always appropriate.\nIn this study\, we investigate the scope of validity of a solar-calibrated mixing length over a range of evolutionary phases and input physics for very metal-poor stars\, and find that the solar-calibrated mixing length is widely ineffective at reproducing the observed properties of such stars.
URL:https://www.oa-roma.inaf.it/event/seminar-by-meridith-joyce/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20180112T114500
DTEND;TZID=Europe/Rome:20180112T124500
DTSTAMP:20260408T141507
CREATED:20171215T072607Z
LAST-MODIFIED:20171215T072607Z
UID:4743-1515757500-1515761100@www.oa-roma.inaf.it
SUMMARY:Not all stars are the Sun: rethinking the Mixing Length
DESCRIPTION:Characterizing heat transport in stars is notoriously complicated\, and the task of reproducing the physics involved with high precision on stellar evolutionary timescales is a long-standing problem in stellar modeling. For this reason\, convection in 1-D stellar evolution codes is addressed primarily through a framework known as mixing length theory (MLT). In this simplified picture\, the efficiency of convective heat transport is encapsulated by the mixing length parameter alpha_{MLT}\, measured in pressure scale heights.\nWhile it is well understood that our nearest star is not a valid representation of stars in general\, it remains the standard procedure to calibrate alpha_{MLT} according to solar specifications\, and then to apply this value in any stellar model\, regardless of mass or composition. However\, there has been growing evidence that the use of a solar-calibrated mixing length is not always appropriate.\nIn this study\, we investigate the scope of validity of a solar-calibrated mixing length over a range of evolutionary phases and input physics for very metal-poor stars\, and find that the solar-calibrated mixing length is widely ineffective at reproducing the observed properties of such stars.
URL:https://www.oa-roma.inaf.it/event/seminar-by-meridith-joyce-2/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20180116T114500
DTEND;TZID=Europe/Rome:20180116T124500
DTSTAMP:20260408T141507
CREATED:20170917T091053Z
LAST-MODIFIED:20170917T091053Z
UID:3513-1516103100-1516106700@www.oa-roma.inaf.it
SUMMARY:Rossby number calculations for fully convective stars
DESCRIPTION:The Rossby number is a quantity that gauges the relative importance of\nrotation in astrophysical flows. In particular\, it plays a significant role\nin mean-field\, alpha-Omega dynamo models as it is directly related to the\n“dynamo number” which\, in turn\, measures the efficiency of the magnetic field\ngeneration. From an observational standpoint\, the Rossby number has been\nwidely used to correlate either coronal or chromospheric magnetic activity of\nlow-mass stars with their rotation. A fundamental problem with this\nrotation-activity relationship is the determination of the convective turnover\ntime tau_c\, on which the Rossby number depends\, and that can be obtained\nfrom some empirical relations or from stellar models. The ATON stellar\nevolution code has been used in the near past to calculate Rossby numbers\nfor solar-type stars and now\, in view of the recent discovery of fully\nconvective stars in the non-saturated region of the rotation-activity\nrelationship\, is being used to extend those calculations to very low mass\nstars.
URL:https://www.oa-roma.inaf.it/event/seminar-by-louiz-temistoklis-mendes/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20180116T114500
DTEND;TZID=Europe/Rome:20180116T124500
DTSTAMP:20260408T141507
CREATED:20170917T091053Z
LAST-MODIFIED:20170917T091053Z
UID:4730-1516103100-1516106700@www.oa-roma.inaf.it
SUMMARY:Rossby number calculations for fully convective stars
DESCRIPTION:The Rossby number is a quantity that gauges the relative importance of\nrotation in astrophysical flows. In particular\, it plays a significant role\nin mean-field\, alpha-Omega dynamo models as it is directly related to the\n“dynamo number” which\, in turn\, measures the efficiency of the magnetic field\ngeneration. From an observational standpoint\, the Rossby number has been\nwidely used to correlate either coronal or chromospheric magnetic activity of\nlow-mass stars with their rotation. A fundamental problem with this\nrotation-activity relationship is the determination of the convective turnover\ntime tau_c\, on which the Rossby number depends\, and that can be obtained\nfrom some empirical relations or from stellar models. The ATON stellar\nevolution code has been used in the near past to calculate Rossby numbers\nfor solar-type stars and now\, in view of the recent discovery of fully\nconvective stars in the non-saturated region of the rotation-activity\nrelationship\, is being used to extend those calculations to very low mass\nstars.
URL:https://www.oa-roma.inaf.it/event/seminar-by-louiz-temistoklis-mendes-2/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20180123T114500
DTEND;TZID=Europe/Rome:20180123T124500
DTSTAMP:20260408T141507
CREATED:20170907T063712Z
LAST-MODIFIED:20170907T063712Z
UID:3437-1516707900-1516711500@www.oa-roma.inaf.it
SUMMARY:Deep\, multi-band photometry of low-mass stars to reveal young clusters: a blind study of the NGC 2264 region
DESCRIPTION:The LSST survey will provide multi-epoch\, multi-wavelength (u\,g\,r\,i\,z\,y) mapping of the Southern Hemisphere\, with a single-visit depth of r~24.5 and a gain of three magnitudes by the end of the program. This unprecedented spatial coverage will enable detection of young\, pre-main sequence stars and stellar clusters down to distances of 5-10 kpc. A crucial and challenging step for spatial analyses of large stellar populations is measuring the extinction Av of individual objects. Multi-color photometry on a (r-i\, g-r) or (i-J\, r-i) diagram offers a direct solution to this issue for M-type stars: indeed\, while the color locus of early-type (< K7) stars on these diagrams is parallel to the reddening vector\, the color locus traced by M-type stars is tilted with respect to the reddening vector\, which enables a straightforward and empirical measurement of their Av. By investigating the correlation between extinction and spatial properties of M-type stars in a given field\, it is therefore possible to reconstruct the structure of the region and probe the nature of its population. In this study\, we test the method on the NGC 2264 field. We selected a 2°x2° area centered on the NGC 2264 cluster\, and collected the available r\,i\,J photometry from existing large-scale surveys (notably Pan-STARRS and UKIDSS). Then\, assuming no prior knowledge on the nature of stars in the field\, we used the (i-J\, r-i) diagram to identify and deredden M-type stars in the sample\, and the (r-i\, r) + (RA\, Dec) diagrams to investigate the nature and spatial distribution of stars as a function of their Av. We derived a non-uniform distribution of Av across the region\, and could distinguish between a diffuse field population and a clustered stellar population toward the center of the field. An a posteriori comparison between the inferred spatial density map of the clustered population and the literature census of the NGC 2264 cluster enabled us to assess the performance of the method and its predictive capability.
URL:https://www.oa-roma.inaf.it/event/seminar-by-laura-venuti/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20180123T114500
DTEND;TZID=Europe/Rome:20180123T124500
DTSTAMP:20260408T141507
CREATED:20170907T063712Z
LAST-MODIFIED:20170907T063712Z
UID:4728-1516707900-1516711500@www.oa-roma.inaf.it
SUMMARY:Deep\, multi-band photometry of low-mass stars to reveal young clusters: a blind study of the NGC 2264 region
DESCRIPTION:The LSST survey will provide multi-epoch\, multi-wavelength (u\,g\,r\,i\,z\,y) mapping of the Southern Hemisphere\, with a single-visit depth of r~24.5 and a gain of three magnitudes by the end of the program. This unprecedented spatial coverage will enable detection of young\, pre-main sequence stars and stellar clusters down to distances of 5-10 kpc. A crucial and challenging step for spatial analyses of large stellar populations is measuring the extinction Av of individual objects. Multi-color photometry on a (r-i\, g-r) or (i-J\, r-i) diagram offers a direct solution to this issue for M-type stars: indeed\, while the color locus of early-type (< K7) stars on these diagrams is parallel to the reddening vector\, the color locus traced by M-type stars is tilted with respect to the reddening vector\, which enables a straightforward and empirical measurement of their Av. By investigating the correlation between extinction and spatial properties of M-type stars in a given field\, it is therefore possible to reconstruct the structure of the region and probe the nature of its population. In this study\, we test the method on the NGC 2264 field. We selected a 2°x2° area centered on the NGC 2264 cluster\, and collected the available r\,i\,J photometry from existing large-scale surveys (notably Pan-STARRS and UKIDSS). Then\, assuming no prior knowledge on the nature of stars in the field\, we used the (i-J\, r-i) diagram to identify and deredden M-type stars in the sample\, and the (r-i\, r) + (RA\, Dec) diagrams to investigate the nature and spatial distribution of stars as a function of their Av. We derived a non-uniform distribution of Av across the region\, and could distinguish between a diffuse field population and a clustered stellar population toward the center of the field. An a posteriori comparison between the inferred spatial density map of the clustered population and the literature census of the NGC 2264 cluster enabled us to assess the performance of the method and its predictive capability.
URL:https://www.oa-roma.inaf.it/event/seminar-by-laura-venuti-2/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20180125T114500
DTEND;TZID=Europe/Rome:20180125T124500
DTSTAMP:20260408T141507
CREATED:20180117T053837Z
LAST-MODIFIED:20180117T053837Z
UID:3891-1516880700-1516884300@www.oa-roma.inaf.it
SUMMARY:Modern core-collapse supernova nucleosynthesis
DESCRIPTION:Massive stars and their core-collapse supernovae are key contributors to the evolution and chemical enrichment of galaxies. Despite over 50 years of research\, the explosion mechanism of core-collapse supernovae is still not fully understood\, which hinders nucleosynthesis predictions. In a previous\, proof-of-principle study\, we have established a modern method to induced explosions in spherically symmetric (otherwise non-exploding) simulations to calculate the nucleosynthesis. This method (PUSH method) includes two aspects that are crucial for nucleosynthesis: One\, the mass cut is emerging from the simulation\, consistently with the explosion energy. And two\, neutrino-interactions with matter are included. In this talk\, I will discuss the nucleosynthesis predictions from our PUSH models and put the results in the context of other nucleosynthesis predictions
URL:https://www.oa-roma.inaf.it/event/talk-by-carla-frohlich/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20180125T114500
DTEND;TZID=Europe/Rome:20180125T124500
DTSTAMP:20260408T141507
CREATED:20180117T053837Z
LAST-MODIFIED:20180117T053837Z
UID:4744-1516880700-1516884300@www.oa-roma.inaf.it
SUMMARY:Modern core-collapse supernova nucleosynthesis
DESCRIPTION:Massive stars and their core-collapse supernovae are key contributors to the evolution and chemical enrichment of galaxies. Despite over 50 years of research\, the explosion mechanism of core-collapse supernovae is still not fully understood\, which hinders nucleosynthesis predictions. In a previous\, proof-of-principle study\, we have established a modern method to induced explosions in spherically symmetric (otherwise non-exploding) simulations to calculate the nucleosynthesis. This method (PUSH method) includes two aspects that are crucial for nucleosynthesis: One\, the mass cut is emerging from the simulation\, consistently with the explosion energy. And two\, neutrino-interactions with matter are included. In this talk\, I will discuss the nucleosynthesis predictions from our PUSH models and put the results in the context of other nucleosynthesis predictions
URL:https://www.oa-roma.inaf.it/event/talk-by-carla-frohlich-2/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20180130T080000
DTEND;TZID=Europe/Rome:20180130T170000
DTSTAMP:20260408T141507
CREATED:20170728T202224Z
LAST-MODIFIED:20170728T202224Z
UID:3364-1517299200-1517331600@www.oa-roma.inaf.it
SUMMARY:The wee free magnetic elements on the photosphere: a turbulent story
DESCRIPTION:The study of the dynamics of the photosphere allow us to investigate the physical processes occurring in both the interior of the Sun and in the higher layers of the solar atmosphere due the magnetic coupling between the photosphere and the corona. This field concerns many basic stellar processes such as: global dynamo\, turbulent convection and super-hot corona.\nIn this talk\, we report on the recent results on the transport of small scale magnetic field by advection/diffusion as seen on different data-sets from ground-based and space telescopes. We compare those results with simplified advective models that mimic the motion scales observed on the solar surface.\nWe will digress on how the advection of the smallest magnetic elements on the solar surface affects the toroidal-to-poloidal conversion in the solar cycle\, on how it can be used to estimate the possible nano-flare contribution to the coronal heating and on its consequences on transiting exo-planet detection.
URL:https://www.oa-roma.inaf.it/event/seminar-by-dario-del-moro/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Rome:20180130T080000
DTEND;TZID=Europe/Rome:20180130T170000
DTSTAMP:20260408T141507
CREATED:20170728T202224Z
LAST-MODIFIED:20170728T202224Z
UID:4719-1517299200-1517331600@www.oa-roma.inaf.it
SUMMARY:The wee free magnetic elements on the photosphere: a turbulent story
DESCRIPTION:The study of the dynamics of the photosphere allow us to investigate the physical processes occurring in both the interior of the Sun and in the higher layers of the solar atmosphere due the magnetic coupling between the photosphere and the corona. This field concerns many basic stellar processes such as: global dynamo\, turbulent convection and super-hot corona.\nIn this talk\, we report on the recent results on the transport of small scale magnetic field by advection/diffusion as seen on different data-sets from ground-based and space telescopes. We compare those results with simplified advective models that mimic the motion scales observed on the solar surface.\nWe will digress on how the advection of the smallest magnetic elements on the solar surface affects the toroidal-to-poloidal conversion in the solar cycle\, on how it can be used to estimate the possible nano-flare contribution to the coronal heating and on its consequences on transiting exo-planet detection.
URL:https://www.oa-roma.inaf.it/event/seminar-by-dario-del-moro-2/
LOCATION:Aula Gratton
CATEGORIES:Seminari
END:VEVENT
END:VCALENDAR