The Planetary Nebula Spectrograph survey of S0 galaxy kinematics

Data and overview^⋆

¹ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
e-mail: aricorte@gmail.com
² University of Nottingham, School of Physics and Astronomy, University Park, NG7 2 RD Nottingham, UK
³ Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, 85741 Garching, Germany
⁴ University of California Observatories, 1156 High Street, Santa Cruz, CA 95064, USA
⁵ Department of Physics and Astronomy, San José State University, One Washington Square, San Jose, CA 95192, USA
⁶ Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Capodimonte, via Moiariello 16, 80131 Naples, Italy
⁷ Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
⁸ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
⁹ Dipartimento di Fisica, Università “Federico II”, Naples, Italy
¹⁰ Research School of Astronomy and Astrophysics, Australian National University, Canberra, Australia
¹¹ Centre for Astrophysics & Supercomputing, Swinburne University, Hawthorn VIC 3122, Australia

Received: 29 August 2012
Accepted: 10 October 2012

Abstract

Context. The origins of S0 galaxies remain obscure, with various mechanisms proposed for their formation, likely depending on environment. These mechanisms would imprint different signatures in the galaxies’ stellar kinematics out to large radii, offering a method for distinguishing between them.

Aims. We aim to study a sample of six S0 galaxies from a range of environments, and use planetary nebulae (PNe) as tracers of their stellar populations out to very large radii, to determine their kinematics in order to understand their origins.

Methods. Using a special-purpose instrument, the Planetary Nebula Spectrograph, we observe and extract PNe catalogues for these six systems.

Results. We show that the PNe have the same spatial distribution as the starlight, that the numbers of them are consistent with what would be expected in a comparable old stellar population in elliptical galaxies, and that their kinematics join smoothly onto those derived at smaller radii from conventional spectroscopy.

Conclusions. The high-quality kinematic observations presented here form an excellent set for studying the detailed kinematics of S0 galaxies, in order to unravel their formation histories. We find that PNe are good tracers of stellar kinematics in these systems. We show that the recovered kinematics are largely dominated by rotational motion, although with significant random velocities in most cases.