Mira, or Omicron Ceti, is now visible to the naked eye. Mira was predicted to return to maximum brightness in October, but is already visible with the naked eye at around magnitude four. Hopefully, Mira will remain visible to the naked eye, or at least in binoculars, for the remainder of the autumn.
Also, Eta Geminorum, which is currently visible in the pre-dawn sky, is unusually faint at magnitude 3.6.
Hopefully, this autumn will present us with plenty of opportunities to observe both stars.
Two new stars have been added to the observing program: R Lyrae and RY Draconis. Both of these stars are suitable for the beginner, or more experienced observer, who likes a challenge. While both stars are easy to find, both are very red stars, and that means it hard to make accurate visual estimates. However, with patience and perseverance, it is still possible to make accurate observations. Hopefully, you’ll try your hand at observing either, or both, of these stars.
The Annual Report for 2019 is now available for download. Look under the Section Report heading, or click the link below:
Variable Star Reports
Chi Cygni is a favourite long-period variable on the SPA programme and it is due to reach maximum at the end of January. It has already reached the sixth magnitude, so should be easily seen in binoculars. It may even be visible to the naked eye from dark sky sites.
Unfortunately, from the UK, Cygnus is very low in the western sky as night is falling, and after sunset, there will only be an interval of a couple of hours in which to make some observations.
If you’re able to observe in the early evening, then please send any observations to the SPA.
Betelgeuse, or Alpha Orionis, has been usually faint over the past few weeks.
Usually, Betelgeuse varies between magnitudes 0.2 and 1.0, however, Betelgeuse is now below the first magnitude. This is not unprecedented behaviour for Betelgeuse, but it is the faintest this star has been for fifty years.
Like all massive stars, Betelgeuse will end its life as a supernova, possibly in the next million years or so. Although it’s unlikely, it is possible that this unusual behaviour could be indicative of pre-supernova behaviour. When Betelgeuse does go supernova, it will outshine the Moon and be visible in the daytime.
The chances of Betelgeuse going supernova in our lifetime is slim, however, it does pay to keep an eye on Betelgeuse’s behaviour, just in case!
The long period variable Mira (Omicron Ceti) is now bright enough to be seen in binoculars, even from light polluted sites. From dark sky sites it may be visible with the naked eye as it approaches maximum in November. For UK observers, Cetus is low in the south-east in the early evening, but over the course of the night, it will be rising higher in the sky.
Conversely, there have been some observations suggesting that R CrB has faded slightly over the course of September (from magnitude 6.1 to 6.9). This could only be a slight fade, with R CrB remaining visible in binoculars until such time as it brightens again. However, this could be the start of other long fade to minimum brightness. Corona Borealis is low in the western sky as darkness descends, but provided you have good western horizons, it should be possible to make some more observations before the star disappears behind the Sun.
The long-period variable, R Trianguli, varies between magnitudes of about six and twelve with a period of seven and a half months. It is predicted to reach maximum brightness in October and is already bright enough to be seen in binoculars.
If your not already observing this star, now is a good time to start. Finder charts can be found on the SPA’s website.
If you are looking to add some new variables to your observing list, then here are some stars you may want to consider.
Delphinus contains two easy to find variables: EU Del and U Del. Both EU Del and U Del are pulsating red giants and both are classified as semi-regulars (SRB). EU Del has an amplitude of 5.4 – 6.7 and a period of about 59 days. U Del has an amplitude of 6.1 – 7.6 and a period of about 120 days.
In the nearby constellation of Serpens, the bright variable Tau 4 Ser can be found not far from R Serpentis. Tau 4 Ser is another semi-regular variable (SRB) with an amplitude of 5.9 – 7.1, and a period of 87 days.
Below are finder charts for these stars, which have been adapted from the BAA Charts.
Three of the Mira stars on the SPA program are will be visible in binoculars during May. T Cephei, a popular circumpolar star with a typical range of 6.0 – 10.5 was recently observed at about the seventh magnitude. It is currently on the rise and is predicted to reach maximum brightness in May.
Two more easy to find Mira stars on the SPA program are R Serpentis and R Bootis. R Serpentis variability was first observed by the German astronomer K.L.Harding in 1826. Harding is now best remembered as the discoverer of Juno; the third asteroid to be discovered. R Serpentis has a typical range of 6.9 – 13.4 and is predicted to reach maximum brightness in May. At the end of April, it was observed to be around the eighth magnitude.
R Bootis variability was first observed by the two German astronomers, E.Schonfeld and F.W.Argelander of Bonn Observatory while they complied their star atlas; Bonner Durchmusterung. R Bootis has a typical range of 7.2 – 12.3 and when it was last observed in April, it had a magnitude of 9.5. As it is also predicted to reach maximum this month, it should become visible in
binoculars over the course of May.
If you out in the early evening you can still see the constellation of Orion low in the west; not long after sunset. Not far above Betelgeuse is U Orionis; a Mira type variable that typically varies between magnitudes six and twelve. During April we’ll have a brief chance to observe this star, in binoculars or a small telescope, before it disappears behind the Sun, at the end of the month.
U Orionis is predicted to reach maximum brightness in April and is just becoming bright enough to be seen in binoculars. One member, Johnathan Shanklin, has already observed U Orionis at just below the tenth magnitude. Hopefully, if the weather co-operates, we will all get a chance to observe this star before it disappears below the horizon.