Stellar Population Gradients in Bulges along the Hubble Sequence: I. The Data

TL;DR

This paper introduces a comprehensive dataset of spectroscopic observations of 32 edge-on spiral galaxy bulges, detailing the methods for measuring their stellar population and dynamical gradients, laying groundwork for future analysis of bulge formation scenarios.

Contribution

It provides detailed spectroscopic data and measurement procedures for bulge stellar populations and dynamics, enabling future analysis of bulge formation.

Findings

Data set of dynamical parameters and line-strength indices for 32 bulges

Methodology for measuring gradients in stellar populations and dynamics

Foundation for future analysis of bulge formation scenarios

Abstract

This is the first paper presenting our long-term project aimed at studying the nature of bulges through the analysis of their stellar population gradients. We present deep spectroscopic observations along the minor axis and the data reduction for a sample of 32 bulges of edge-on spiral galaxies. We explain in detail our procedures to measure their dynamical parameters (rotation curves and velocity dispersion profiles) and line-strength indices, including the conversion to the Lick/IDS system. Tables giving the values of the dynamical parameters and line-strength indices at each galactocentric radius are presented (in electronic form) for each galaxy of the sample. The derived line-strength gradients from this dataset will be analyzed in a forthcoming paper to set constraints on the different scenarios for the formation of the bulges.