October 2024 - Double Star of the Month
In the north of Andromeda near the border with Cassiopeia and close to the line of zero RA lies 22 And, a star of visual magnitude 5.0. Moving about one degree west and slightly south brings us to BU 997 (00 04 57.53 +45 40 25.6), a pair of stars of magnitudes 7.6 and 9.4 and currently 3".8 apart. They should be easily seen in 15-cm although they were discovered by S. W. Burnham with the Dearborn 18.5-inch refractor. The stars show little motion, apart from a slight reduction in the pair's separation.
In addition to his numbered discoveries, Burnham also noted a number of wide, faint pairs which have since been placed into the Washington Double Star catalog. One of these, BU 9001 (formerly BU 997a but renumbered to fit in with the new format of three letters and four numbers) lies about 30' due south. The stars are very unequal (6.7 and 10.6) and the companion lies at 235 degrees and 21". Larger apertures might see the 13.7 star added by Thomas Espin in 1914 at 107 degrees and 16".
LAL 192 (23 54 21.40 -27 02 34.5) is another example of a pair being re-catalogued. It appeared in Dunlop's catalogue of 1826 as DUN 253 but was apparently changed to its current moniker at Lick Observatory when the double star catalogue existed on index cards but no-one seems to know why. It is, in any case, well worth seeking out. Easily seen in 10-cm the 6.8 and 7.4 magnitude components are presently 6".5 apart, a distance which is slowly increasing. Ross Gould using 10-cm records colours of pale yellow with a slight difference in shade
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LAL 193 is in the neighbourhood. It is 1.5 degrees ENE of LAL 192 and the magnitude 6.2 SAO 192262, a distinctly orange-hued star lies between the two. LAL 193 consists of two early-F dwarfs of magnitudes 8.1 and 8.3. The current separation and position angle are 19".4 and 169 degrees and they also appear to comprise a physical system.
Bob Argyle - Double Star Section Director
