Welcome to KROME

(better science through chemistry)


KROME is a nice and friendly chemistry package for a wide range of astrophysical simulations.

Given a chemical network (in CSV format) it automatically generates all the routines needed to solve the kinetic of the system, modelled as a system of coupled Ordinary Differential Equations. It provides different options which make it unique and very flexible. Any suggestions and comments are welcomed.

Please use the krome's users mailing list for any problem related to the package or if you have additional comments.

KROME is developed and maintained by Tommaso Grassi, Stefano Bovino, and many others.

KROME is an open-source package, GNU-licensed, and any improvements provided by the users is well accepted.


2015 edition

Visit the website by clicking here

2014 edition

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Get in touch with the KROME's developers and the community by downloading, forking, and discussing the main issues


Download the latest tested version of KROME from the test page


Clone, fork, and contribute to the developement of KROME on bitbucket

Get Help

Discuss the issues of KROME with the developers and the other users



Take a look at the KROME's paper on arXiv

User Guide

Read the Wiki to get started

Quick Start

Get started with KROME!


KROME has been employed in the following papers:
  1. Connecting the evolution of thermally pulsing asymptotic giant branch stars to the chemistry in their circumstellar envelopes, Marigo et al. (2015)
  2. Modelling the chemistry of star forming filaments, Seifried et al. (2015)
  3. Modelling the chemical evolution in galaxies with KROME, Bovino et al. (2015)
  4. Witnessing the birth of a supermassive protostar, Latif et al. (2015)
  5. Impact of dust cooling on direct collapse black hole formation, Latif et al. (2015)
  6. Seeding High Redshift QSOs by Collisional Runaway in Primordial Star Clusters, Katz et al. (2015)
  7. Assessing inflow rates in atomic cooling halos: implications for direct collapse black holes, Latif et al. (2015)
  8. The origin of spin in galaxies: clues from simulations of atomic cooling haloes, Prieto et al. (2015)
  9. The formation of supermassive black holes in rapidly rotating disks, Latif et al. (2015)
  10. How realistic UV spectra and X-rays suppress the abundance of direct collapse black holes, Latif et al. (2015)
  11. Disc fragmentation and the formation of Population III stars, Latif et al. (2015)
  12. The chemical evolution of self-gravitating primordial disks, Schleicher et al. (2015)
  13. KROME - a package to embed chemistry in astrophysical simulations, Grassi et al. (2014)
  14. Effects of turbulence and rotation on protostar formation as a precursor to seed black holes, Van Borm et al. (2014)
  15. Dark-matter halo mergers as a fertile environment for low-mass Population III star formation, Bovino et al. (2014)
  16. Formation of carbon-enhanced metal-poor stars in the presence of far ultraviolet radiation, Bovino et al. (2014)
  17. The formation of massive primordial stars in the presence of moderate UV backgrounds, Latif et al. (2014)
  18. A UV flux constraint on the formation of direct collapse black holes, Latif et al. (2014)
  19. Primordial star formation: relative impact of H2 three-body rates and initial conditions, Bovino et al. (2014)
  20. Reducing Si population in the ISM by charge exchange collisions with He+: a quantum modelling of the process, Satta et al. (2013)
  21. Impact of an accurate modelling of primordial chemistry in high-resolution studies, Bovino et al. (2013)
  22. CH+ depletion by atomic hydrogen: accuracy of new rates in photo-dominated and self-shielded environments, Bovino et al. (2013)
  23. Exploring planetary biomarkers: a new physical method coupled with new computational tool, Simoncini and Grassi (2013)


Astrophysicists model the formation of the oldest-known star in our galaxy

The astrochemistry package KROME has been employed by scientists at the Universities of Göttingen and Copenhagen to model the formation of the oldest-known star in the Milky Way, SMSS J031300.36-670839.3, with the cosmological hydrodynamics code Enzo. The simulations included the observed stellar abundance patterns for the metals, as well as the dynamics of gas and dark matter. The star modeled is part of the class of the carbon-enhanced metal poor stars, with tiny abundances of metals but relatively enhanced fractions of carbons. The simulations show that efficient cooling is still possible under these conditions, and that the gas reaches the temperature of the cosmic microwave background during the collapse. As a result, efficient fragmentation may occur, and the formation of low-mass stars becomes possible.

The attached illustration shows projections of the gas density, temperature and the fraction of ionized carbon in the central region where the star forms, in simulations with different abundances of the heavy elements, from 0.01 to 0.0001 times the solar value. The results show that a strong transition occurs for a carbon abundance of 0.01 times the solar value, providing a pathway for the formation of low-mass stars.

phys.org | SNM | UniGoe | INAF (Italian) | ApJL | arXiv

About Us

KROME is developed by several astrophysicists and chemists from different host institutions

Main developer:    Tommaso GrassiSTARPLAN, Natural History Museum of Denmark / NBI(tgrassi AT nbi.dk)
Co-developer and Enzo interface: Stefano BovinoHamburg Observatory, Hamburg (stefano.bovino AT uni-hamburg.de)
RAMSES interface:    Joaquìn PrietoICC, University of Barcelona (IEEC-UB) (joaquin.prieto.brito AT gmail.com)
FLASH interface:    Daniel SeifriedUniversity of Köln (seifried AT ph1.uni-koeln.de)
Planetary atmospheres:   Eugenio SimonciniINAF - Arcetri, Florence, Italy (eugenio.simoncini AT gmail.com)
Supervisor / RAMSES:   Troels HaugbølleSTARPLAN, Natural History Museum of Denmark / NBI(haugboel AT nbi.dk)
Supervisor:   Dominik SchleicherDepartamento de Astronomía, Universidad de Concepción (dschleicher AT astro-udec.cl)
Supervisor:   Francesco GianturcoIntitut fuer Ionenphysik und Angewandte Physik, Innsbruck (francesco.gianturco AT uibk.ac.at)