Popular Astronomy

Share to Facebook Share to Twitter Stumble It More...

Sun, 15 May 2016 - T Cephei is near maximum

The Mira type variable star T Cephei is currently near its peak brightness and is readily visible in binoculars

T Cephei has an extreme brightness range between magnitudes 5.4 and 11.0, although the average peak brightness is around mag 6.0. The average interval between maxima is 389 days (just under 13 months), although individual maxima do sometimes occur several weeks earlier or later than expected.

The brightness variations of T Cephei are not fully predictable.  For example, it does not rise and fall in brightness at a constant rate.  In particular, it often pauses around mag 8.0 during the rise. This pause seems to have become unusually prolonged in recent years, lasting for 6 weeks or more before the brightening then resumes.

Predictions for 2016 suggested that the latest maximum would occur in late May or early June. However, by late April, T Cephei was already close to mag 6.0. No significant further brightening occurred in early May and there are some indications that T Cephei might  actually have faded slightly, raising the possibility that maximum actually occurred near the start of May. However, the true picture will not become clear for several more weeks.

T Cephei is located near the star Beta Cephei and is circumpolar from the UK. You can follow its brightness changes using this finder chart in which the comparison stars are labelled with their magnitudes (with the decimal points omitted). Thus, for example, '64' labels a  star of magnitude 6.4.

Additional finder charts an more information about T Cephei can be found in this guide


Added by: Tracie Heywood