Maria Giuseppina Di Mauro - Academia.edu (original) (raw)
Papers by Maria Giuseppina Di Mauro
This paper presents a simple and efficient equation of state which can be used for quick and accu... more This paper presents a simple and efficient equation of state which can be used for quick and accurate computation of the thermodynamic functions of partly ionized and weakly coupled plasmas (Bi, Di Mauro and Christensen-Dalsgaard 2000). Based on the free energy minimization method, the improvement of the equation of state includes a detailed account of the physical processes of non-ideal effects consisting of electron degeneracy, Coulomb coupling and pressure ionization. The non-ideal corrections to the equation of state are calculated under solar interior conditions. The result reveals that the contribution is quite significant, and hence modifies the thermodynamic properties of the plasma substantially.
Frontiers in Astronomy and Space Sciences
We present a new synergic strategy that merges the potential of asteroseismology with solar space... more We present a new synergic strategy that merges the potential of asteroseismology with solar space weather/climate techniques in order to characterize solar-like stars and their interaction with hosted exoplanets. The method is based on the use of seismic data obtained by the space missions Kepler/K2 and TESS Transiting Exoplanet Survey Satellite, coupled with stellar activity estimates deduced from ground-based campaigns (e.g., Mount Wilson Observatory HK Project). Our investigation allows us to determine not only highly accurate fundamental parameters of the mother star and its orbiting planet, but also to study the stellar magnetic activity and the star-planet interaction: in analogy to the Sun-Earth system, it is possible to infer the mean stellar wind acting on the exoplanet in order to define the conditions of the exoplanetary environment and the erosion of its atmosphere with an impact on the habitability of the planet.
<p>The solar activity in form of coronal mass ejections or solar wind distu... more <p>The solar activity in form of coronal mass ejections or solar wind disturbances, such as slow or high speed streams, affects the circumterrestrial electromagnetic environment, with a primary effect on the magnetosphere, compressing and perturbing it. Here, in order to connect the long-term solar activity variations to solar wind properties, we use measurement of a proxy for chromospheric activity, the Ca II K index, and solar wind OMNI data for the time interval 1965-2021, which almost entirely covers the last 5 solar cycles. By using both a cross correlation and a mutual information approach, a 3.6-year mean lag has been found between Ca II K index and solar wind dynamic pressure. This result allows us to obtain a relationship between the solar UV emission and the solar wind dynamic pressure, enabling us to derive the Earth’s magnetospheric extension over the last 5 solar cycles.<br>Moreover, the advantage of having used the Ca II K index proxy is that the relation found for the Sun can be easily extended to other stars with similar properties (i.e. Sun-like stars). To this scope, the model is then used to study the effect of stellar wind dynamic pressure on the magnetosphere of Earth-like planets orbiting at 1 AU around a sample of Sun-like stars.</p>
During the last decades, numerous observational and theoretical efforts in the study of solar osc... more During the last decades, numerous observational and theoretical efforts in the study of solar oscillations, have brought to a detailed knowledge of the interior of the Sun. While this discipline has not yet exhausted its resources and scientists are still working on further refinements of the solar models and to solve the numerous still open questions, Asteroseismology, which aims to infer the structural properties of stars which display multimode pulsations, has just entered in its golden age. In fact, the space missions CoRoT and Kepler dedicated to the observation of stellar oscillations, have already unveiled primary results on the structural properties of the stars producing a revolution in the way we study the stellar interiors. Here, the modern era of Helio-and Asteroseismology is reviewed with emphasis on results obtained for the Sun and its solar-like counterparts.
The Astrophysical Journal, 2018
We present the asteroseismic study of the early red-giant star KIC4448777, complementing and int... more We present the asteroseismic study of the early red-giant star KIC4448777, complementing and integrating a previous work, aimed at characterizing the dynamics of its interior by analyzing the overall set of data collected by the Kepler satellite during the four years of its first nominal mission. We adopted the Bayesian inference code DIAMONDS for the peak bagging analysis and asteroseismic splitting inversion methods to derive the internal rotational profile of the star. The detection of new splittings of mixed modes, which are more concentrated in the very inner part of the helium core, allowed us to reconstruct the angular velocity profile deeper into the interior of the star and to disentangle the details better than in Paper I: the helium core rotates almost rigidly about 6 times faster than the convective envelope, while part of the hydrogen shell seems to rotate at a constant velocity about 1.15 times lower than the He core. In particular, we studied the internal shear layer between the fast-rotating radiative interior and the slow convective zone and we found that it lies partially inside the hydrogen shell above r;0.05R and extends across the core-envelope boundary. Finally, we theoretically explored the possibility for the future capabilty to sound the convective envelope in the red-giant stars and we concluded that the inversion of a set of splittings with only low-harmonic degree l3, even supposing a very large number of modes, will not allow us to resolve the rotational profile of this region in detail.
The Astrophysical Journal, 2015
NASA's re-purposed Kepler mission-dubbed K2-has brought new scientific opportunities that were no... more NASA's re-purposed Kepler mission-dubbed K2-has brought new scientific opportunities that were not anticipated for the original Kepler mission. One science goal that makes optimal use of K2's capabilities, in particular its 360-degree ecliptic field of view, is galactic archaeology-the study of the evolution of the Galaxy from the fossil stellar record. The thrust of this research is to exploit high-precision, time-resolved photometry from K2 in order to detect oscillations in red giant stars. This asteroseismic information can provide estimates of stellar radius (hence distance), mass and age of vast numbers of stars across the Galaxy. Here we present the initial analysis of a subset of red giants, observed towards the North Galactic Gap, during the mission's first full science campaign. We investigate the feasibility of using K2 data for detecting oscillations in red giants that span a range in apparent magnitude and evolutionary state (hence intrinsic luminosity). We demonstrate that oscillations are detectable for essentially all cool giants within the log g range ∼ 1.9-3.2. Our detection is complete down to Kp ∼ 14.5, which results in a seismic sample with little or no detection bias. This sample is ideally suited to stellar population studies that seek to investigate potential shortcomings of contemporary Galaxy models.
ABSTRACT ADvanced Astronomy for HELIophysics (ADAHELI) is a Small Mission to study the structure ... more ABSTRACT ADvanced Astronomy for HELIophysics (ADAHELI) is a Small Mission to study the structure and fast dynamics of the low solar atmosphere, performing Visible-NIR monochromatic and broad-band observations. The mission will achieve millimeter full disk observations as well. The ADAHELI Team has succesfully completed, in December 2008, the Phase A study awarded by the Italian Space Agency (ASI). The Interferometer for SOlar Dynamics (ISODY), on board the ADAHELI satellite, comprises a Gregorian telescope and its focal plane suite. The advanced design focal plane suite uses fast CMOS cameras for investigating photospheric and chromospheric fast dynamics and structure. ISODY is equipped with a pioneering focal plane suite composed of a spectral channel, based upon a tandem of Fabry-Perot interferometers operating in the visible-NIR spectral region, a broad band channel for high resolution imaging, and a correlation tracker used as an image stabilization system. ADAHELI's mission profile has been tailored to limit the spacecraft' s radial velocity in the Sunward direction, to not exceed ?4 km/s, during 95% of the yearly orbit, to allow a continuous use of the on-board interferometer. © 2010 SPIE.
Proceedings of the International Astronomical Union, 2013
We discuss the potential of asteroseismic inversion to study the internal dynamics of solar-type ... more We discuss the potential of asteroseismic inversion to study the internal dynamics of solar-type stars and to reconstruct the evolution of the internal rotation from the main sequence to the red-giant phase. In particular, we consider the use of gravity and mixed modes and the application of different inversion methods.
Careful statistical study of the rotational split for each single mode of radial number n have be... more Careful statistical study of the rotational split for each single mode of radial number n have been carried out based on the different time series dedicated for the search of solar oscillations of low spherical degrees ell = 0, 1, 2, 3, 4. The data has been taken during 830 days by GONG. The frequency of a mode with fixed n,m,ell has been determined from different data sets, where this mode is well visible. Then the rotational splitting has been calculated from all possible combinations, and the histogram distributions for each n has been build to reveal the probablest value of the splitting and the statistical error of its estimation. The dependence of the rotational splitting on the radial order n is shown for ell = 1, 2, 3, 4. Finally, we infer the variation of the angular velocity of the Sun with latitude and radius by helioseismic inversion of the GONG set of data, which consists of the very accurate splittings of the low degree modes (ell = 1-4), derived as described above, co...
Astrophysics and Space Science, 2010
arXiv: Solar and Stellar Astrophysics, 2017
During the last 50 years we have been witness of an extraordinary revolution in the knowledge and... more During the last 50 years we have been witness of an extraordinary revolution in the knowledge and understanding of our star thanks to the development of Helioseismology, the study of solar oscillations. Similar to what happens on the Earth during earthquakes, the interior of the Sun is continuously pervaded by seismic waves which produce small oscillations on the photosphere. These oscillations bring the signature of several processes which happen in the interior of the solar structure and the seismic frequencies of the oscillation modes detected on the solar surface are directly related to physical parameters of the internal layers crossed by the seismic waves. The study of oscillations represents, then, the only method to infer directly the internal structure and dynamics of the Sun. This article will present the general characteristics of solar oscillations, the main important results and the advances obtained in stellar physics thanks to the methods of Helioseismology.
We present an asteroseismic approach to study the dynamics of the stellar interior in red-giant s... more We present an asteroseismic approach to study the dynamics of the stellar interior in red-giant stars by asteroseismic inversion of the splittings induced by the stellar rotation on the oscillation frequencies. We show preliminary results obtained for the red giant KIC4448777 observed by the space mission Kepler.
Over the last decade, thanks to the successful space missions launched to detect stellar pulsatio... more Over the last decade, thanks to the successful space missions launched to detect stellar pulsations, Asteroseismology has produced an extraordinary revolution in astrophysics, unveiling a wealth of results on structural properties of stars over a large part of the H-R diagram. Particularly impressive has been the development of Asteroseismology for stars showing solar-like oscillations, which are excited and intrinsically damped in stars with convective envelopes. Here I will review on the modern era of Asteroseismology with emphasis on results obtained for solar-like stars and discuss its potential for the advancement of stellar physics.
Recent revisions of the determination of the solar composition have resulted in solar models in m... more Recent revisions of the determination of the solar composition have resulted in solar models in marked disagreement with helioseismic inferences. The effect of the composition change on the model is largely caused by the change in the opacity. Thus we wish to determine an intrinsic opacity change that would compensate for the revision of the composition. By comparing models computed with the old and revised composition we determine the required opacity change. Models are computed with the opacity thus modified and used as reference in helioseismic inversions to determine the difference between the solar and model sound speed. An opacity increase varying from around 30 per cent near the base of the convection zone to a few percent in the solar core results in a sound-speed profile, with the revised composition, which is essentially indistinguishable from the original solar model. As a function of the logarithm of temperature this is well represented by a simple cubic fit. The physica...
1 ESO 2 Thüringer Landessternwarte Tautenburg, Germany 3 Max-Planck-Institut für Astronomie, Heid... more 1 ESO 2 Thüringer Landessternwarte Tautenburg, Germany 3 Max-Planck-Institut für Astronomie, Heidelberg, Germany 4 Observatorio Nacional, Rio de Janeiro, Brazil 5 Departamento de Fisica, Universidade Federal do Rio Grande do Norte, Natal, Brazil 6 Kiepenheuer-Institut für Sonnenphysik, Freiburg, Germany 7 INAF – Osservatorio Astronomico di Trieste, Italy 8 INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica, Roma, Italy 9 Max-Planck-Institut für Astrophysik, Garching bei München, Germany
During the last decades, numerous observational and theoretical efforts in the study of solar osc... more During the last decades, numerous observational and theoretical efforts in the study of solar oscillations, have brought to a detailed knowledge of the interior of the Sun. While this discipline has not yet exhausted its resources and scientists are still working on further refinements of the solar models and to solve the numerous still open questions, Asteroseismology, which aims to infer the structural properties of stars which display multi-mode pulsations, has just entered in its golden age. In fact, the space missions CoRoT and Kepler dedicated to the observation of stellar oscillations, have already unveiled primary results on the structural properties of the stars producing a revolution in the way we study the stellar interiors. Here, the modern era of Helio- and Asteroseismology is reviewed with emphasis on results obtained for the Sun and its solar-like counterparts.
This paper presents a simple and efficient equation of state which can be used for quick and accu... more This paper presents a simple and efficient equation of state which can be used for quick and accurate computation of the thermodynamic functions of partly ionized and weakly coupled plasmas (Bi, Di Mauro and Christensen-Dalsgaard 2000). Based on the free energy minimization method, the improvement of the equation of state includes a detailed account of the physical processes of non-ideal effects consisting of electron degeneracy, Coulomb coupling and pressure ionization. The non-ideal corrections to the equation of state are calculated under solar interior conditions. The result reveals that the contribution is quite significant, and hence modifies the thermodynamic properties of the plasma substantially.
Frontiers in Astronomy and Space Sciences
We present a new synergic strategy that merges the potential of asteroseismology with solar space... more We present a new synergic strategy that merges the potential of asteroseismology with solar space weather/climate techniques in order to characterize solar-like stars and their interaction with hosted exoplanets. The method is based on the use of seismic data obtained by the space missions Kepler/K2 and TESS Transiting Exoplanet Survey Satellite, coupled with stellar activity estimates deduced from ground-based campaigns (e.g., Mount Wilson Observatory HK Project). Our investigation allows us to determine not only highly accurate fundamental parameters of the mother star and its orbiting planet, but also to study the stellar magnetic activity and the star-planet interaction: in analogy to the Sun-Earth system, it is possible to infer the mean stellar wind acting on the exoplanet in order to define the conditions of the exoplanetary environment and the erosion of its atmosphere with an impact on the habitability of the planet.
<p>The solar activity in form of coronal mass ejections or solar wind distu... more <p>The solar activity in form of coronal mass ejections or solar wind disturbances, such as slow or high speed streams, affects the circumterrestrial electromagnetic environment, with a primary effect on the magnetosphere, compressing and perturbing it. Here, in order to connect the long-term solar activity variations to solar wind properties, we use measurement of a proxy for chromospheric activity, the Ca II K index, and solar wind OMNI data for the time interval 1965-2021, which almost entirely covers the last 5 solar cycles. By using both a cross correlation and a mutual information approach, a 3.6-year mean lag has been found between Ca II K index and solar wind dynamic pressure. This result allows us to obtain a relationship between the solar UV emission and the solar wind dynamic pressure, enabling us to derive the Earth’s magnetospheric extension over the last 5 solar cycles.<br>Moreover, the advantage of having used the Ca II K index proxy is that the relation found for the Sun can be easily extended to other stars with similar properties (i.e. Sun-like stars). To this scope, the model is then used to study the effect of stellar wind dynamic pressure on the magnetosphere of Earth-like planets orbiting at 1 AU around a sample of Sun-like stars.</p>
During the last decades, numerous observational and theoretical efforts in the study of solar osc... more During the last decades, numerous observational and theoretical efforts in the study of solar oscillations, have brought to a detailed knowledge of the interior of the Sun. While this discipline has not yet exhausted its resources and scientists are still working on further refinements of the solar models and to solve the numerous still open questions, Asteroseismology, which aims to infer the structural properties of stars which display multimode pulsations, has just entered in its golden age. In fact, the space missions CoRoT and Kepler dedicated to the observation of stellar oscillations, have already unveiled primary results on the structural properties of the stars producing a revolution in the way we study the stellar interiors. Here, the modern era of Helio-and Asteroseismology is reviewed with emphasis on results obtained for the Sun and its solar-like counterparts.
The Astrophysical Journal, 2018
We present the asteroseismic study of the early red-giant star KIC4448777, complementing and int... more We present the asteroseismic study of the early red-giant star KIC4448777, complementing and integrating a previous work, aimed at characterizing the dynamics of its interior by analyzing the overall set of data collected by the Kepler satellite during the four years of its first nominal mission. We adopted the Bayesian inference code DIAMONDS for the peak bagging analysis and asteroseismic splitting inversion methods to derive the internal rotational profile of the star. The detection of new splittings of mixed modes, which are more concentrated in the very inner part of the helium core, allowed us to reconstruct the angular velocity profile deeper into the interior of the star and to disentangle the details better than in Paper I: the helium core rotates almost rigidly about 6 times faster than the convective envelope, while part of the hydrogen shell seems to rotate at a constant velocity about 1.15 times lower than the He core. In particular, we studied the internal shear layer between the fast-rotating radiative interior and the slow convective zone and we found that it lies partially inside the hydrogen shell above r;0.05R and extends across the core-envelope boundary. Finally, we theoretically explored the possibility for the future capabilty to sound the convective envelope in the red-giant stars and we concluded that the inversion of a set of splittings with only low-harmonic degree l3, even supposing a very large number of modes, will not allow us to resolve the rotational profile of this region in detail.
The Astrophysical Journal, 2015
NASA's re-purposed Kepler mission-dubbed K2-has brought new scientific opportunities that were no... more NASA's re-purposed Kepler mission-dubbed K2-has brought new scientific opportunities that were not anticipated for the original Kepler mission. One science goal that makes optimal use of K2's capabilities, in particular its 360-degree ecliptic field of view, is galactic archaeology-the study of the evolution of the Galaxy from the fossil stellar record. The thrust of this research is to exploit high-precision, time-resolved photometry from K2 in order to detect oscillations in red giant stars. This asteroseismic information can provide estimates of stellar radius (hence distance), mass and age of vast numbers of stars across the Galaxy. Here we present the initial analysis of a subset of red giants, observed towards the North Galactic Gap, during the mission's first full science campaign. We investigate the feasibility of using K2 data for detecting oscillations in red giants that span a range in apparent magnitude and evolutionary state (hence intrinsic luminosity). We demonstrate that oscillations are detectable for essentially all cool giants within the log g range ∼ 1.9-3.2. Our detection is complete down to Kp ∼ 14.5, which results in a seismic sample with little or no detection bias. This sample is ideally suited to stellar population studies that seek to investigate potential shortcomings of contemporary Galaxy models.
ABSTRACT ADvanced Astronomy for HELIophysics (ADAHELI) is a Small Mission to study the structure ... more ABSTRACT ADvanced Astronomy for HELIophysics (ADAHELI) is a Small Mission to study the structure and fast dynamics of the low solar atmosphere, performing Visible-NIR monochromatic and broad-band observations. The mission will achieve millimeter full disk observations as well. The ADAHELI Team has succesfully completed, in December 2008, the Phase A study awarded by the Italian Space Agency (ASI). The Interferometer for SOlar Dynamics (ISODY), on board the ADAHELI satellite, comprises a Gregorian telescope and its focal plane suite. The advanced design focal plane suite uses fast CMOS cameras for investigating photospheric and chromospheric fast dynamics and structure. ISODY is equipped with a pioneering focal plane suite composed of a spectral channel, based upon a tandem of Fabry-Perot interferometers operating in the visible-NIR spectral region, a broad band channel for high resolution imaging, and a correlation tracker used as an image stabilization system. ADAHELI's mission profile has been tailored to limit the spacecraft' s radial velocity in the Sunward direction, to not exceed ?4 km/s, during 95% of the yearly orbit, to allow a continuous use of the on-board interferometer. © 2010 SPIE.
Proceedings of the International Astronomical Union, 2013
We discuss the potential of asteroseismic inversion to study the internal dynamics of solar-type ... more We discuss the potential of asteroseismic inversion to study the internal dynamics of solar-type stars and to reconstruct the evolution of the internal rotation from the main sequence to the red-giant phase. In particular, we consider the use of gravity and mixed modes and the application of different inversion methods.
Careful statistical study of the rotational split for each single mode of radial number n have be... more Careful statistical study of the rotational split for each single mode of radial number n have been carried out based on the different time series dedicated for the search of solar oscillations of low spherical degrees ell = 0, 1, 2, 3, 4. The data has been taken during 830 days by GONG. The frequency of a mode with fixed n,m,ell has been determined from different data sets, where this mode is well visible. Then the rotational splitting has been calculated from all possible combinations, and the histogram distributions for each n has been build to reveal the probablest value of the splitting and the statistical error of its estimation. The dependence of the rotational splitting on the radial order n is shown for ell = 1, 2, 3, 4. Finally, we infer the variation of the angular velocity of the Sun with latitude and radius by helioseismic inversion of the GONG set of data, which consists of the very accurate splittings of the low degree modes (ell = 1-4), derived as described above, co...
Astrophysics and Space Science, 2010
arXiv: Solar and Stellar Astrophysics, 2017
During the last 50 years we have been witness of an extraordinary revolution in the knowledge and... more During the last 50 years we have been witness of an extraordinary revolution in the knowledge and understanding of our star thanks to the development of Helioseismology, the study of solar oscillations. Similar to what happens on the Earth during earthquakes, the interior of the Sun is continuously pervaded by seismic waves which produce small oscillations on the photosphere. These oscillations bring the signature of several processes which happen in the interior of the solar structure and the seismic frequencies of the oscillation modes detected on the solar surface are directly related to physical parameters of the internal layers crossed by the seismic waves. The study of oscillations represents, then, the only method to infer directly the internal structure and dynamics of the Sun. This article will present the general characteristics of solar oscillations, the main important results and the advances obtained in stellar physics thanks to the methods of Helioseismology.
We present an asteroseismic approach to study the dynamics of the stellar interior in red-giant s... more We present an asteroseismic approach to study the dynamics of the stellar interior in red-giant stars by asteroseismic inversion of the splittings induced by the stellar rotation on the oscillation frequencies. We show preliminary results obtained for the red giant KIC4448777 observed by the space mission Kepler.
Over the last decade, thanks to the successful space missions launched to detect stellar pulsatio... more Over the last decade, thanks to the successful space missions launched to detect stellar pulsations, Asteroseismology has produced an extraordinary revolution in astrophysics, unveiling a wealth of results on structural properties of stars over a large part of the H-R diagram. Particularly impressive has been the development of Asteroseismology for stars showing solar-like oscillations, which are excited and intrinsically damped in stars with convective envelopes. Here I will review on the modern era of Asteroseismology with emphasis on results obtained for solar-like stars and discuss its potential for the advancement of stellar physics.
Recent revisions of the determination of the solar composition have resulted in solar models in m... more Recent revisions of the determination of the solar composition have resulted in solar models in marked disagreement with helioseismic inferences. The effect of the composition change on the model is largely caused by the change in the opacity. Thus we wish to determine an intrinsic opacity change that would compensate for the revision of the composition. By comparing models computed with the old and revised composition we determine the required opacity change. Models are computed with the opacity thus modified and used as reference in helioseismic inversions to determine the difference between the solar and model sound speed. An opacity increase varying from around 30 per cent near the base of the convection zone to a few percent in the solar core results in a sound-speed profile, with the revised composition, which is essentially indistinguishable from the original solar model. As a function of the logarithm of temperature this is well represented by a simple cubic fit. The physica...
1 ESO 2 Thüringer Landessternwarte Tautenburg, Germany 3 Max-Planck-Institut für Astronomie, Heid... more 1 ESO 2 Thüringer Landessternwarte Tautenburg, Germany 3 Max-Planck-Institut für Astronomie, Heidelberg, Germany 4 Observatorio Nacional, Rio de Janeiro, Brazil 5 Departamento de Fisica, Universidade Federal do Rio Grande do Norte, Natal, Brazil 6 Kiepenheuer-Institut für Sonnenphysik, Freiburg, Germany 7 INAF – Osservatorio Astronomico di Trieste, Italy 8 INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica, Roma, Italy 9 Max-Planck-Institut für Astrophysik, Garching bei München, Germany
During the last decades, numerous observational and theoretical efforts in the study of solar osc... more During the last decades, numerous observational and theoretical efforts in the study of solar oscillations, have brought to a detailed knowledge of the interior of the Sun. While this discipline has not yet exhausted its resources and scientists are still working on further refinements of the solar models and to solve the numerous still open questions, Asteroseismology, which aims to infer the structural properties of stars which display multi-mode pulsations, has just entered in its golden age. In fact, the space missions CoRoT and Kepler dedicated to the observation of stellar oscillations, have already unveiled primary results on the structural properties of the stars producing a revolution in the way we study the stellar interiors. Here, the modern era of Helio- and Asteroseismology is reviewed with emphasis on results obtained for the Sun and its solar-like counterparts.