Giovanni Picogna

Giovanni Picogna

I am a post-doc in the Star and Planet Formation group led by Barbara Ercolano

Publications

Published works

Disk evolution and dispersal

Lowest accreting protoplanetary discs consistent with X-ray photoevaporation driving their final dispersal

Published in Monthly Notices of the Royal Astronomical Society, 2023

We use disc population synthesis models to interpret recent observations of the lowest accreting protoplanetary discs, comparing predictions from EUV-driven, FUV-driven, and X-ray-driven photoevaporation models. We show that the recent observational data of stars with low accretion rates (low accretors) point to X-ray photoevaporation as the preferred mechanism driving the final stages of protoplanetary disc dispersal.

Recommended citation: Ercolano, Picogna & Monsch (2023). "Lowest accreting protoplanetary discs consistent with X-ray photoevaporation driving their final dispersal." Monthly Notices of the Royal Astronomical Society. 526, 1. https://academic.oup.com/mnrasl/article-abstract/526/1/L105/7260862

Observability of photoevaporation signatures in the dust continuum emission of transition discs

Published in Monthly Notices of the Royal Astronomical Society, 2023

We study a sample of transition discs obtained from radiation-hydrodynamic simulations of internally photoevaporated discs, and focus on the dust dynamics relevant for current Atacama Large Millimetre Array observations. We then compared our results with gaps opened by a super-Earth/giant planets, finding that the photoevaporated cavity steepness depends mildly on gap size. However, the spectral index is higher at the cavity edge with respect to the planetary case. The combination of cavity steepness and spectral index might reveal the true nature of transition discs.

Recommended citation: Picogna et al. (2023). "Observability of photoevaporation signatures in the dust continuum emission of transition discs." Monthly Notices of the Royal Astronomical Society. 523, 3. https://academic.oup.com/mnras/article-abstract/523/3/3318/7170048

The dispersal of protoplanetary discs - III. Influence of stellar mass on disc photoevaporation

Published in Monthly Notices of the Royal Astronomical Society, 2021

We study the influence of stellar mass on circumstellar disc mass-loss rates due to internal X-ray irradiation. We find a linear relationship between stellar mass and mass-loss rates, and provide analytical relations. Out models correctly predict the observed trend of inner-disc lifetime as a function of stellar mass.

Recommended citation: Picogna et al. (2021). "The dispersal of protoplanetary discs - III. Influence of stellar mass on disc photoevaporation." Monthly Notices of the Royal Astronomical Society. 508, 3. https://academic.oup.com/mnras/article-abstract/508/3/3611/6385760

The dispersal of protoplanetary discs - II: photoevaporation models with observationally derived irradiating spectra

Published in Monthly Notices of the Royal Astronomical Society, 2021

We presented model spectra based on spectral parameters derived from the observations of young stars in the Orion nebula cluster. The spectra are then used to calculate new photoevaporation prescriptions that can be used in disc and planet population synthesis models. Our models clearly show that disc wind mass loss rates are controlled by the stellar luminosity in the soft (100eV to 1keV) X-ray band.

Recommended citation: Ercolano, Picogna et al. (2021). "The dispersal of protoplanetary discs - II: photoevaporation models with observationally derived irradiating spectra." Monthly Notices of the Royal Astronomical Society. 508, 2. https://academic.oup.com/mnras/article/508/2/1675/6373466

The interpretation of protoplanetary disc wind diagnostic lines from X-ray photoevaporation and analytical MHD models

Published in Monthly Notices of the Royal Astronomical Society, 2020

The combination of MHD and photoevaporative winds could reproduce the main features of the observed line profiles. Our results suggest that the Gaussian decomposition does not allow for a clear distinction of flux from different wind regions and that the line broadening is often dominated by the velocity gradient in the outflow rather than by Keplerian rotation. We show that observed correlations between BLVC and NLVC do not necessarily imply a common origin in an extended MHD wind.

Recommended citation: Weber, Ercolano, Picogna et al. (2020). "The interpretation of protoplanetary disc wind diagnostic lines from X-ray photoevaporation and analytical MHD models." Monthly Notices of the Royal Astronomical Society. 496, 1. https://academic.oup.com/mnras/article/496/1/223/5850787

The dispersal of protoplanetary discs – I. A new generation of X-ray photoevaporation models

Published in MNRAS, 2019

Roughly half of observed transition discs cavities and accretion rates could be reproduced by internal X-ray photo-evaporation.

Recommended citation: Picogna et al. (2019). "The dispersal of protoplanetary discs – I. A new generation of X-ray photoevaporation models." Monthly Notices of the Royal Astronomical Society. Volume 487, Issue 1, p.691-701. http://giovannipicogna.github.io/files/X-ray-photoevaporation-1.pdf

A photoevaporative gap in the closest planet-forming disc

Published in Monthly Notices of the Royal Astronomical Society, 2017

We show that the disc around TW Hya, the closest protoplanetary disc to Earth, may be the first object where a photoevaporative gap has been imaged around the time at which it is being created. The detected gap in the ALMA images is consistent with the expectations of X-ray photoevaporation models, thus not requiring the presence of a planet.

Recommended citation: Ercolano, Rosotti, Picogna & Testi (2017). "A photoevaporative gap in the closest planet-forming disc." Monthly Notices of the Royal Astronomical Society. 464, 1. https://academic.oup.com/mnrasl/article/464/1/L95/2264423

Dust evolution

Observability of photoevaporation signatures in the dust continuum emission of transition discs

Published in Monthly Notices of the Royal Astronomical Society, 2023

We study a sample of transition discs obtained from radiation-hydrodynamic simulations of internally photoevaporated discs, and focus on the dust dynamics relevant for current Atacama Large Millimetre Array observations. We then compared our results with gaps opened by a super-Earth/giant planets, finding that the photoevaporated cavity steepness depends mildly on gap size. However, the spectral index is higher at the cavity edge with respect to the planetary case. The combination of cavity steepness and spectral index might reveal the true nature of transition discs.

Recommended citation: Picogna et al. (2023). "Observability of photoevaporation signatures in the dust continuum emission of transition discs." Monthly Notices of the Royal Astronomical Society. 523, 3. https://academic.oup.com/mnras/article-abstract/523/3/3318/7170048

Particle accretion onto planets in discs with hydrodynamic turbulence

Published in Astronomy & Astrophysics, 2018

Planetesimal accumulation in circumbinary disks appears to be prevented close to the stellar pair by the gravitational perturbations of the circumbinary disk. The observed planets possibly formed in the outer regions of the disk and then migrated inside by tidal interaction with the disk.

Recommended citation: Picogna et al. (2018). "Particle accretion onto planets in discs with hydrodynamic turbulence." Astronomy & Astrophysics. 616, A116. https://www.aanda.org/articles/aa/full_html/2018/08/aa32523-17/aa32523-17.html

Anisotropic hydrodynamic turbulence in accretion disks

Published in Astronomy & Astrophysics, 2017

We investigated whether the VSI can possibly explain the observed anomalous angular momentum transport in accretion disks, and meridional circulation patterns. We found that the vertical stress is significantly stronger than the radial stress, providing additional evidence for the anisotropy with important consequences for the dust evolution.

Recommended citation: Stoll, Kley & Picogna (2017). "Anisotropic hydrodynamic turbulence in accretion disks." Astronomy & Astrophysics. 599, L6. https://www.aanda.org/articles/aa/full_html/2017/03/aa30226-16/aa30226-16.html

A photoevaporative gap in the closest planet-forming disc

Published in Monthly Notices of the Royal Astronomical Society, 2017

We show that the disc around TW Hya, the closest protoplanetary disc to Earth, may be the first object where a photoevaporative gap has been imaged around the time at which it is being created. The detected gap in the ALMA images is consistent with the expectations of X-ray photoevaporation models, thus not requiring the presence of a planet.

Recommended citation: Ercolano, Rosotti, Picogna & Testi (2017). "A photoevaporative gap in the closest planet-forming disc." Monthly Notices of the Royal Astronomical Society. 464, 1. https://academic.oup.com/mnrasl/article/464/1/L95/2264423

How do giant planetary cores shape the dust disk? HL Tauri system

Published in Astronomy & Astrophysics, 2015

The features observed in the HL Tau system can be explained through the presence of several massive cores that shape the dust disk where the inner planet(s) have a mass of the order of $0.07 M_{Jup}$ and the outer one(s) of the order of $0.35 M_{Jup}$.

Recommended citation: Picogna & Kley (2015). "How do giant planetary cores shape the dust disk? HL Tauri system." Astronomy & Astrophysics. 584, A110. http://GiovanniPicogna.github.io/files/HLTau.pdf

Planet formation in binary stars

Circumbinary discs: Numerical and physical behaviour

Published in Astronomy & Astrophysics, 2017

For varying binary eccentricities $e_bin$ we find two separate branches in the gap size and eccentricity diagram. The bifurcation occurs at around $e_{crit} \approx 0.18$ where the gap is smallest with the shortest $T_{prec}$.

Recommended citation: Thun, Kley & Picogna. (2017). "Circumbinary discs: Numerical and physical behaviour." Astronomy & Astrophysics. Volume 604, id.A102, 19 pp.. https://www.aanda.org/articles/aa/abs/2017/08/aa30666-17/aa30666-17.html

Three-dimensional modeling of radiative disks in binaries

Published in Astronomy & Astrophysics, 2013

We perform 3D numerical simulations of disks in binaries with different initial dynamical configurations and physical parameters. The disk is significantly heated up by spiral waves and mass transfer, and the high gas temperature moves the snow line outwards. The strength of the spiral arms, disk heating, and mass exchange depends strongly on the binary separation.

Recommended citation: Picogna & Marzari (2013). "Three-dimensional modeling of radiative disks in binaries." Astronomy & Astrophysics. 556, A148. https://www.aanda.org/articles/aa/full_html/2013/08/aa21860-13/aa21860-13.html

Influence of the circumbinary disk gravity on planetesimal accumulation in the Kepler-16 system

Published in Astronomy & Astrophysics, 2013

Planetesimal accumulation in circumbinary disks appears to be prevented close to the stellar pair by the gravitational perturbations of the circumbinary disk. The observed planets possibly formed in the outer regions of the disk and then migrated inside by tidal interaction with the disk.

Recommended citation: Marzari et al. (2013). "Influence of the circumbinary disk gravity on planetesimal accumulation in the Kepler-16 system." Astronomy & Astrophysics. 553, A71. https://www.aanda.org/articles/aa/full_html/2013/05/aa20893-12/aa20893-12.html