Andy's Astronomy Page

A Blurb about My Research

The primary goal of my work over recent years has been to determine how our Galaxy (the Milky Way) formed. The kinematics (motions within the Galaxy), spatial distribution, and chemical composition of the stars in our Galaxy have "locked in" the memory of the properties of the gas clouds which formed them. By selecting RR Lyrae stars (radially pulsating variable stars which are also found on the "horizontal branches" of globular clusters) to study, I ensure that I am looking at stars that were born at least 10-12 billion years ago, when the Galaxy itself was forming.

My current focus is on four samples of RR Lyrae stars, each in a different region of the Galaxy. By comparing the properties of the stars in different regions, I hope to place more constraints on pictures of how our Galaxy formed. The regions I am studying are:

• Solar Neighborhood: about 300 stars within 2.5 kpc of the Sun.
• The Inner Halo: 3 to 6 kpc from the Galactic Center.
• The High Halo: >5 kpc from the Galactic Plane, above/below the Sun.
• The Bulge/Halo Interface: 2 kpc from the Galactic Center, where the bulge and halo overlap.

Since moving to BGSU, I have also used our 0.5-m telescope, along with other small-aperture telescopes around the world, to measure the brightness and color of several types of variable stars including RR Lyrae and Long-Period Variables. This work has engaged many BGSU undergraduate and Masters students in astronomical research.

Links to Different Aspects of My Research

• Current Preprints (pre-publication)
• Refereed Publications, including DATA tables (ascii).
• Recent Conference Proceedings
• Photometry of RR Lyrae in Globular Clusters

Links to Related Work by Other People

• Doug Welch's RR Lyrae database.
• Bill Harris's catalog of parameters for Milky Way Globular Clusters .
• Bill Harris's catalog of Extra-Galactic Globular Clusters .
• Jean-Marc Perelmuter's Globular Cluster Homepage

Education Resources.

Some Fun, Non-professional Astronomy

• Weighing Jupiter -- Computing the mass and mean density of Jupiter from simple observations of the Galillean moons.
• How to observe orbiting satellites.
• Meteor showers.
• Fred Espenak's eclipse page contains excellent info on uncoming eclipses (both solar and B lunar), past eclipses, and on how to observe eclipses.

Links to Out-of-the-Way Astro Utilities

• Where in the world is Dr. Carmen San Diego? Link to STARLINK's ASTRO database of astronomy addresses for Individuals, Establishments, etc.
• Searchable access to the HST Guide Star Catalog -- returns positions and magnitudes of GSC stars within a given radius of given coordinates.
• Super-Mongo graphics package, online manual and tutorial.