| Object | Mira, The Wonderful (omicron Ceti, SAO 129825) |
| Telescope | 14" Meade RCX400 at f/8 |
| Spectrograph / CCD | SBIG SGS, SBIG ST-7XME at -20C and -25C |
| Resolution | Low resolution mode (150 lines/mm grating, 4.3 Angstroms/pixel dispersion, ~ 9 Angstrom resolution (R ~ 720 at H-alpha) |
| Integration Details | 5 x 90s and 12 x 30s, dark subtracted and median combined |
| Date / Median Time (UTC) | 05-Feb-2007 0315 UTC and 06-Feb-2007 0340 UTC |
| Moon Phase | 92% and 86% |
| Approximate Airmass | 1.60 and 1.59 |
| CCD Response Curve Source | Epsilon Orionis |
| Wavelength Calibration | H and Ne lamps |
| Software Used | TheSky, CCDSoft, CCDStack, Iris, vSpec, Excel, Photoshop |
| Comments | Mira is a long-period variable and a binary star system.
It is the first in a class of long-period variables known as
"Mira Variables". The period of Mira is very roughly 11
months. The spectra taken in early February, 2007 were
taken near maximum brightness, when the star was at
approximately at visual magnitude 3. The star appeared
very red and was easily visible to the naked eye. In addition to many absorption lines from "metals", the spectrum of Mira exhibits emission lines in Hydrogen. The spectrum is dominated by broad absorption by the molecule titanium oxide (TiO). Near maximum, the spectral type is approximately M5e but it gradually grows later to type M9e at minimum. Mira is a huge star; if it were our sun, its thin atmosphere would probably reach out to Mars. It's also a very cool star (literally as well as figuratively!) The image was taken with a refractor on Feb. 20, 2007. |