Presentation #105.04 in the session Molecular Clouds and the ISM — iPoster Session.
The Triangulum Galaxy (M33) is the third most massive galaxy in the Local Group (after the Andromeda and Milky Way galaxies). It is an actively star-forming dwarf spiral galaxy and is located at a distance of 859 kpc. M33’s relatively face-on orientation makes it ideal for studying the distribution of stars and gas in its well-defined spiral structure. It houses some of the largest known stellar nurseries, sites of the birth of short-lived but massive stars, dispersed along loose spiral arms that twist into the core. Hot young stars in these star-forming regions ionize the surrounding interstellar medium (ISM) making M33 an excellent laboratory for the study of the energetics of the ISM. In this the second of a series of three AAS posters, we present a study of the physical and chemical properties of the ionized gas component of M33’s ISM. The study uses the DEep Imaging Multi-Object Spectrograph (DEIMOS) multi-slit spectroscopic data from the Triangulum Extended (TREX) survey. The primary purpose of the survey is to study M33’s resolved stellar population. A by-product of this survey is a set of “blank sky” spectra that contain emission lines associated with the ionized gas in the projected vicinity of the primary stellar targets. As explained in the first poster of this series, we have carried out optimal subtraction of the atmospheric airglow emission lines from these sky spectra. We measure M33’s ionized gas ISM emission line fluxes and analyze the flux ratios in a BPT diagram in order to derive constraints on the physical processes that ionized the gas. The regions with the most intense emission lines are used to detect and characterize faint and rare emission lines associated with M33’s ISM.
This research was supported in part by the National Science Foundation and NASA/STScI. This research was conducted under the auspices of the Science Internship Program (SIP) at the University of California Santa Cruz. We wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to work with observations from this mountain.