During the month of November 2011 three bright Mira type stars reach peak brightness and all are easy binocular targets.
The three stars are R Aquilae (R Aql), R Trianguli (R Tri) and R Andromedae (R And). Of these R Aql and R Tri should peak at around magnitude 6 with R And a little bit fainter at magnitude 7. The first two are even visible to the naked eye under dark skies. For most of us living in or near towns and cities some sort of optical aid, such as binoculars or a finderscope, will be required.
The following sky charts show how to locate R Aql, R Tri and R And. For Northern hemisphere observers R Tri and R And are well placed high in the sky this month. In the case of R Aql, since it is located close to the celestial equator and is visible from most parts of the planet. For mid-latitude observers R Aql appears towards the west after sunset.
As typical of Mira stars the minimum brightness is much fainter than the maximum; R Aql and R Tri drop down to at least 12th magnitude with R And bottoming out at magnitude 14. At these sorts of magnitudes ideally a minimum 200mm (8-inch) telescope is required to see R Aql and R Tri, with a much larger scope required to pick out R And.
Since all three stars are currently at or near their peak brightness, now is an excellent opportunity to look outside on a clear night and take time to observe these wonderful variable stars.
R Aql, R Tri, R And - Data Table
|Name||R Aquilae (R Aql)||R Trianguli (R Tri)||R Andromedae (R And)|
|RA (J2000)||19h 06m 22s||02h 37m 02s||00h 24m 02s|
|Dec (J2000)||+08d 13m 48s||+34d 15m 51s||+38d 34m 37s|
|Apparent Magnitude - Extreme range||5.5 -> 12.0||5.4 -> 12.6||5.8 -> 14.9|
|Apparent Magnitude - Average range||6.0 -> 11.6||6.0 -> 11.9||6.9 -> 14.3|
|Spectral type||M7 IIIe||M4 IIIe||S65 III|
|Other Designations||HR 7243, BD+08 3970, SAO 124266||HR 758||HR 90, BD +37° 58, SAO 53860|
|Approx Peak Date||23rd Nov 2011||25th Nov 2011||16th Nov 2011|