| |
 |
| Paper: |
Photometric Metallicities in dSph Systems |
| Volume: |
448, 16th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun |
| Page: |
899 |
| Authors: |
Hughes, J.; Wallerstein, G. |
| Abstract: |
We present part of a project to test Strömgren, Washington, and Sloan filter systems for stellar population studies within SDSS-discovered dSph galaxies. We use the Boötes I dSph as a test case, finding that the Strömgren m1-index gives a more accurate metallicity estimate than the Washington filters for the individual upper-red giant branch stars, but only if 1% photometry is achieved. For individual stars, the resolution for the Strömgren filters in [Fe/H] is about 0.2-0.3 dex, but that very long exposures are necessary in the v-band to obtain useful data at the main-sequence turn-off. The faintness of the red giants in the bluer bands becomes problematic at Boötes I's distance of about 65 kpc. We conclude that Washington filters are better for systems with distances >50 kpc or so, except where there is considerable reddening present (although CT1T2 would still be better than ugriz by a factor of two). For future surveys using the Sloan filters, we recommend adding the Washington C-filter to the Sloan set: the (C–r)-color is the best (and cheapest) metallicity-sensitive compromise for stellar population studies. Using the m1-index and the (C–T1) color, we can detect a metallicity spread of -1.1 < [Fe/H] < -2.7, and we have been able to determine photometric metallicities on the lower red giant branch, which is not possible with the Strömgren system alone. |
|
|
|
|
|
