ForDyS Research Group at INAF Padova

This is the web page of the 'Formation and Dynamics of Stars' (ForDyS) research team at the Astronomical Observatory of Padova. We study the formation and dynamics of stars (and stellar remnants) by means of (many flavours of) N-body simulations. Most of us work in Padova, a lively town in Italy, where Galileo made his first discoveries. Contact us, if you are curious to know more about our research (michela.mapelli[at]!

Further information:


Formation and Dynamics of Stars in Galactic Nuclei:
Galactic nuclei are a unique laboratory to probe extreme physical processes, which occur in vicinity of supermassive black holes (SMBHs).
The innermost parsecs of a galaxy should be a hostile environment for star formation, since the SMBH' tidal shear disrupts any molecular cloud that approaches the galactic centre too much. Despite this, we DO observe hundreds of young stars in the innermost parsec of the Milky Way, and several hints point toward recent episodes of star formation in other nearby galactic nuclei. Recently, JVLA observations suggested even the presence of protoplanetary discs in the central parsec of our Galaxy.

What drives star formation so close to the monster?
We investigate the formation of stars around SMBHs, by means of N-body hydrodynamical simulations. We simulate the disruption of molecular clouds and the formation of circumnuclear rings in galactic nuclei. Our last and topmost challenge is to probe the existence of starless planets bound to SMBHs.
Do you remember Gravity, the movie?

People: Michela Mapelli, Alessandro Ballone, Elisa Bortolas, Mario Spera, Alessandro Trani
Recent publications: Trani et al. 2016; Trani et al. 2016; Mapelli & Trani 2016; Mapelli & Gualandris 2016; Mapelli & Ripamonti 2015; Mapelli, Gualandris & Hayfield 2013; Mapelli et al. 2012.

The nursery of stars: when dynamics meets gas physics and stellar evolution
[05.jpg] Simulating young star clusters is a challenge for computational astrophysics. Three main aspects must be accounted for: (i) the hydro-dynamics of the parent molecular cloud, (ii) the dynamics of the newly formed stars, and (iii) the evolution of stars and binary systems.
The hydrodynamical treatment of the gas is particularly demanding because it requires both very high resolution and a suitable cooling function. Given the high density that can be reached in the core of dense young star clusters, the stellar component requires direct-summation N-body integrators, coupled with up-to-date recipes for stellar evolution and stellar winds.

Our new group at the Observatory of Padova is involved in the most innovative simulations of molecular clouds and young star clusters. We make use of special purpose hardware, especially graphics processing units (GPUs), to meet the challenge of coupling collisional stellar dynamics and stellar evolution.

People: Michela Mapelli, Alessandro Ballone, Mario Spera, Alessandro Trani, Ugo Di Carlo
Recent publications: Spera, Mapelli and Jeffries 2016; Mapelli & the GES collaboration 2015; Trani, Mapelli & Bressan 2014; Mapelli & Bressan 2013.

Massive stellar black holes and intermediate-mass black holes: a keystone for the X-ray Universe and for gravitational waves
In 2009, Mapelli et al. proposed that black holes with mass >>20 Msun (up to 120 Msun) form from the direct collapse of massive stars with metallicity below solar. These massive stellar black holes (MSBHs) graze the mass range of intermediate mass black holes (IMBHs, 100-10 000 Msun) but are of merely stellar nature.
We investigate the impact of MSBHs and IMBHs on the evolution of the X-ray Universe (high-mass X-ray binaries, ultraluminous X-ray sources) from cosmic reionization to the local Universe.
Mergers of IMBHs and MSBHs with stellar black holes or other compact objects are expected to be a powerful source of gravitational waves in the frequency range of Advanced LIGO and Virgo. We are fond of multi-messenger astrophysics!

People: Michela Mapelli, Mario Spera, Nicola Giacobbo, Alessandro Trani, Enrico Montanari
Recent publications: Mapelli 2016; Kimpson, Spera, Mapelli & Ziosi 2016; Spera, Mapelli & Bressan 2015; Ziosi, Mapelli et al. 2014; Mapelli & Zampieri 2014; Mapelli, Annibali et al. 2013; Mapelli, Zampieri et al. 2013; Mapelli et al. 2010; Mapelli et al. 2009.


The Stellar EVolution for N-body (SEVN) code:

SEVN (presented in Spera, Mapelli & Bressan 2015) is our new open source population synthesis code. The mass spectrum of black holes we predicted with SEVN was recently used by the LIGO-Virgo collaboration to constrain the metallicity of the progenitors of GW150914 (Abbott et al. 2016).
SEVN includes (1) up-to-date stellar evolution (through look-up tables), (2) binary evolution, (3) five different recipes for core-collapse supernovae, and (4) an up-to-date formalism for pair-instability and pulsational pair-instability supernovae. Moreover, SEVN is designed to be interfaced with direct-summation N-body codes (such as STARLAB and HiGPUs). We are still developing SEVN and adding new features. You can download the most recent stable version from the link below, or go to our gitlab project. Comments are welcome!

SEVN Release 1.0: this release includes single stellar evolution (through PARSEC stellar tracks, Bressan et al. 2012; Chen et al. 2015), core-collapse supernovae (through Belczynski et al. 2010; Fryer et al. 2012; O'Connor and Ott 2011; Ertl et al. 2016), pair-instability and pulsational pair-instability supernovae (through Woosley 2017), and tools for binary evolution (orbital angular momentum change, wind accretion, tidal evolution, following Hurley et al. 2002). More recipes for binary evolution are still being tested and will be added in the next release. Stay tuned!


Michela Mapelli (PhD) Alessandro Ballone (PhD) Mario Spera (PhD)
Assistant professor, team leader Postdoctoral fellow Postdoctoral fellow
[Elisa Bortolas]
[Nicola Giacobbo]
Elisa Bortolas (Ms) Nicola Giacobbo (Mr) Alessandro Alberto Trani (Mr)
PhD student PhD student PhD student
University of Padova University of Padova SISSA, INAF-OAPD
[Ugo Di Carlo.jpg]
[Adam Dacroury]
Ugo N. Di Carlo (Mr) Enrico Montanari (Mr) Adam Dakroury (Mr)
Master Student Master Student ERASMUS Master Student
University of Padova University of Padova University of Surrey

FORMER MEMBERS (now collaborators):

[Ben Czaja]
[Giulio Dondi]
[Matteo Mazzarini]
Ben Czaja (Mr) Giulio Dondi (Mr) Tom Kimpson (Mr) Matteo Mazzarini (Mr) Brunetto Marco Ziosi (PhD)
Former Master student Master student PhD student PhD student ERP developer
Astromundus fellow University of Padova University College of London Heidelberg University Pixartprinting


  • April 2017: Elisa Bortolas is awarded the first Stefano Magini prize for her Master Thesis. Congratulation Elisa!

  • April 2017: New paper about "Supernova kicks in the Galactic centre" online

  • February 2017: New paper about "Rotation in young massive star clusters" online

  • January 16 2017: First release of SEVN available on our website

  • November 2 2016: Alessandro Ballone joins the ForDyS team as new postdoctoral fellow. Welcome Alessandro!

  • October 1 2016: Nicola Giacobbo starts his PhD at University of Padova, with the ForDyS team. Congratulations Nicola!

  • September 27-28 2016: Ben Czaja, Giulio Dondi and Nicola Giacobbo successfully defended their Theses. Congratulations!

  • Summer 2016: We have got many new publications online. You can find them on ADS. It was a terrific spring for the ForDyS group!

  • August 1 2016: Adam Dakroury joins our team as ERASMUS student. Welcome Adam!

  • May 15 2016: Giulio Dondi joins our team as Bachelor student. Welcome Giulio!

  • April 15 2016: Nicola Giacobbo joins our team as Master student. Welcome Nicola!

  • March 15 2016: Ben Czaja joins our team as Master student. Welcome Ben!

  • March 10 2016: Matteo Mazzarini and Enrico Montanari successfully defended their theses. Congratulations!

  • March 3 2016: ForDyS on 'il Bo' (online magazine of the University of Padova) about the LIGO detection of two massive stellar black holes. Read our outreach paper (in Italian).

  • February 22 2016: ForDyS on MEDIA INAF about the LIGO detection of two massive stellar black holes. Read our outreach paper (in Italian).

  • February 11 2016: LIGO/Virgo's first direct detection of gravitational waves! The mass range of the two black holes (~36,29 Msun) is what we predicted since 2009! Recent paper by Mario Spera and the ForDys group referred to in the detection paper and in the astrophysics implication paper.
    A dream comes true: MASSIVE STELLAR BLACK HOLES EXIST!!!

  • December 15 2015: Michela Mapelli joins the MAORY Science Team. If you do not know what MAORY is read this. ForDyS gives a tiny contribution to the E-ELT!

  • December 10 2015: New paper on the dynamics of circumnuclear rings (by Alessandro Trani et al.) on astroph.

  • November 19 2015: Scighera, the new server of ForDyS is up and running. Welcome Scighera!

  • November 16 2015: Brunetto Ziosi successfully defends his PhD Thesis. Congratulations Brunetto!

  • October 20 2015: New paper on the formation of the circumnuclear ring in the Galactic Centre (by Michela Mapelli & Alessandro Trani) is on astroph.

  • October 1 2015: Elisa Bortolas joins our team as a new PhD student. Welcome Elisa!

  • September 23 2015: A NEW postdoctoral fellowship is available in our group. See the details at this link

  • July 9 2015: Tom Kimpson joins our team for an ERASMUS project. Welcome Tom!

  • June 24 2015: Michela Mapelli is awarded the MERAC prize for theoretical astrophysics!


  • Several PhD projects are available in our group (follow this link). Do not hesitate to contact me if you are intersted!