stellaR: A Package to Manage Stellar Evolution Tracks and Isochrones

Authors

Matteo Dell’Omodarme, Università di Pisa
Giada Valle, Università di Pisa

Date of this Version

6-2013

Document Type

Article

Citation

The R Journal (June 2013) 5(1); Editor: Hadley Wickham

Comments

Copyright 2013, The R Foundation. Open access material. License: CC BY 3.0 Unported

Abstract

We present the R package stellaR, which is designed to access and manipulate publicly available stellar evolutionary tracks and isochrones from the Pisa low-mass database. The procedures for extracting important stages in the evolution of a star from the database, for constructing isochrones from stellar tracks and for interpolating among tracks are discussed and demonstrated.

Due to the advance in the instrumentation, nowadays astronomers can deal with a huge amount of high-quality observational data. In the last decade impressive improvements of spectroscopic and photometric observational capabilities made available data which stimulated the research in the globular clusters field. The theoretical effort of recovering the evolutionary history of the clusters benefits from the computation of extensive databases of stellar tracks and isochrones, such as Pietrinferni et al. (2006); Dotter et al. (2008); Bertelli et al. (2008). We recently computed a large data set of stellar tracks and isochrones, “The Pisa low-mass database” (Dell’Omodarme et al., 2012), with up to date physical and chemical inputs, and made available all the calculations to the astrophysical community at the Centre de Données astronomiques de Strasbourg (CDS)1, a data center dedicated to the collection and worldwide distribution of astronomical data.

In most databases, the management of the information and the extraction of the relevant evolutionary properties from libraries of tracks and/or isochrones is the responsibility of the end users. Dueto its extensive capabilities of data manipulation and analysis, however, R is an ideal choice for these tasks. Nevertheless R is not yet well known in astrophysics; up to December 2012 only seven astronomical or astrophysical-oriented packages have been published on CRAN (see the CRAN Task View Chemometrics and Computational Physics).

The package stellaR (Dell’Omodarme and Valle, 2012) is an effort to make available to the astrophysical community a basic tool set with the following capabilities: retrieve the required calculations from CDS; plot the information in a suitable form; construct by interpolation tracks or isochrones of compositions different to the ones available in the database; construct isochrones for age not included in the database; extract relevant evolutionary points from tracks or isochrones.