Color Maps of the Ohio State University Bright Spiral Galaxy Survey

Melissa Butner, Austin Peay State University

Susana Deustua, advisor

Goal

Investigate the distribution and properties of the interstellar medium: dust and gas, and of the stellar population in each galaxy by undertaking a pixel by pixel analysis.

Questions we are interested in:• what is the star formation rate?• how is the dust distributed and how does this affect

extinction?• how do these properties compare to other spiral

galaxies?

The OSUBSGS

The Ohio State University Bright Spiral Galaxy Survey

~200 spiral galaxies B <= 12 Selected from RC3 BVRJHK band images D < 6.5’ −80◦ < δ < +50◦ (due to observational limits)

Advantages of using Multi-wavelength Data

Extinction measurement is independent of the dust temperature.

Probe the temperatures and masses of the dust components to better constrain the heating mechanism for the dust.

Helps in separating star and dust contributions to galaxy emission

Steps for pixel based analysis

Align (register) images Match PSFs Determine flux and color for each pixel in each

galaxy Use Pixel z or similar code to determine the

spectral energy distribution of stars (from models of star formation)

Use color maps to see the distribution of ISM components

Compare SED and color maps

ic5235 Before Registration

B image J image

Image Size - 6.8’ x 6.8 ‘Pixel Scale – 0.40 “/pixel

Image Size – 4.4’ x 4.6’Pixel Scale – 1.16 “/pixel

ic5325 After Registration

B image J image

PSF Match

Image FWHM Before

FWHM After

B 6.84 6.84

V 6.58 6.07

R 6.04 6.30

J 4.58 21.31 ?

H 4.66 5.73

K 4.77 5.74

Color Maps

B V B - V

Color Maps

B – K

B

K

Future Work

• Finish registering

• Apply technique of Matching PSFs and generating color maps.

• Determine the spectral energy distribution

• Compare color maps with SED