MIRA Observations

The objective of this research will be to detect OH masers around old Mira stars, which in the Northern Hemisphere can be found around: U Her, S CrB, W Hya, and R Cas. For radio measurements at T-22 we’ll have to use dark skies as a control measure of cold sky between 2 and 3 degrees off from these Miras. This will be a program for collecting data over a couple of years or more. Mira stars are old variable red giants with an average period of 331 days. However, their magnitudes may vary from a visual minimum magnitude to greater than 4 or 5 magnitude increase (very bright). The hope is that we can detect their OH masers at 1.665GHz and 1.667GHz with circular polarization during the entire cycle of variability. If detection is possible with this receiver on the 18 meter dish[es], then data can be collected on the weekends or whenever the stars are above the horizon. Variable star observations are normally done in the optical, however these OH masers have been rated greater than 1 Jansky in flux. (see article) Previous calibrations with T-22′s 1.420GHz receiver have shown that this is about the limit of sensitivity for our 18 meter dish[es]. However, with suitable tracking capability and dwell time, we may be able to detect these OH maser signatures. Should our data be statistically significant, the hope will be to submit our results to the AAVSO Mira program:http://www.aavso.org/vstar/vsots/archive.shtml#mira which would certaintly be a first, as there are no radio observations of Mira stars in the AAVSO database of variable stars.