IDENTIFICATION CHARTS FOR 42 VARIABLE STARS DISCOVERED AT HARVARD. Arville D. Walker and Margaret Olmsted Harvard College Observatory

Transcription

1 IDENTIFICATION CHARTS FOR 42 VARIABLE STARS DISCOVERED AT HARVARD Arville D. Walker and Margaret Olmsted Harvard College Observatory Some time ago Dr. G. H. Herbig, acting for Commissions 27 and 29 of thé International Astronomical Union, sent to the director of the Harvard College Observatory a list of 45 variable stars for which identification charts were desired. These stars liad been discovered at Harvard, are of current interest, and had proved unidentifiable from the descriptions in existing literature. Charts have now been prepared for 42 of the 45 stars in the list. One of the variables is a catalogue star, a chart for a second lias previously been published, and a third has not yet been identified. Miss Walker made the identifications in part from old records, but she also examined the published position of each star on a sufficiently large number of Harvard plates to prove the variability of the star at that position. Two identifications were provided by Dr. Dorrit Hoffleit of the Maria Mitchell Observatory. Miss Olmsted checked both the variability and the position of each variable star and constructed the charts. Each star has been treated as a separate problem. The individual charts do not follow a uniform system of representing size, area, or magnitude scale. The best plate available was placed in film-to-film contact with a photographic millimeter reseau, and an area was chosen that contained a conspicuous configuration of stars ; the stars were then plotted to simulate as closely as possible their actual appearance on the plate. Only plates with blue-sensitive emulsions were used. When the variable star was fairly bright at minimum and easily recognizable by the pattern of the surrounding bright stars, or when the fainter stars were not very numerous, only one diagram was made. If the variable star appeared in a field rich in faint stars, we plotted those faint stars included inside a small area indicated by a frame within the main chart, but omitted the faint stars outside the frame. In some cases where catalogue stars were scarce in the vicinity of the variable, two charts were made, one small-scale, and one of smaller area but considerably larger scale. A few of the variables were so 495

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9 IDENTIFICATION CHARTS 503 closely surrounded by faint stars of the same or brighter magnitude that it seemed best to include a very small area of even greater enlargement. A catalogue star in each field, identified in Table I, is designated by the letter A. TABLE I Chart No. 1* * 15 16* 17* 18* 19* * * 29* 30* 31* 32* 33 34* 35* Name UFor XZ Eri AH Eri TW Mon SV Pup ST Hya AG Hya XAnt V436 Cen V591 Cen EX Hya V485 Cen NN Cen BV Cen UZ Boo TT Boo BE Cen BR Lup AT Ara V699 Oph TU Oph X Ser YY Sco MM Sco V810 Oph V812 Oph CQ Sco V551 Sgr V557 Sgr HV 7864 YCrA WW Sgr VW Set AA Ser BV Set List of Individual Star Charts 3 h a (1900) 17 s ' Catalogue Star, A CoD BD BD BD BD BD CoD CoD CoD CoD CoD CoD CPD No chart made BD BD No chart made CoD CPD BD BD BD CoD CoD BD BD CoD CoD No chart made CoD CoD CoD BD BD BD Plate A MF MF MC 6746 A B MF B MF MF MF MF MF IR 2204 IR 9971 MF MF MF A A 7701 A 2520 A MF MC B ADH 346 MF B MF MC A A 1072

10 504 WALKER AND OLMSTED Chart No. Name 36 SV Set 18 37* V604=N2 Aql 18 38* HV * CGVul 19 40* V606=N1 Aql KX Aql 19 42* OT Aql 19 43* OW Aql RX Cap CVAqr 21 a (1900) s Catalogne Star, A BD BD BD BD BD BD BD BD BD BD Plate A 4091 MF MF MC A MF MF MF B MF * Notes to Table I : 1. U For. Position given by E. C. Pickering, Harvard Cire. No. 167, BV Cen. There is a variable star at a = 13 h 25 1?1, ô = 54 27'5. No star was found at the given position on 36 plates examined. 16. TT Boo. Enlargement from same plate. 17. BE Cen. Star is CoD BR Lup. Identified from sketch in original record book. Enlargement from same plate. 19. AT Ara. Enlargement from A MM Sco. Framed section is repeated with different magnitude scale and with faint stars added. 28. V551 Sgr. Var. 2 FU Sgr. ; var. 3 not investigated. Enlargement from same plate. 29. V557 Sgr. See chart by L. Plaut, Leiden Ann., 20, 1, 1948 (star 78). 30. HV Enlargement from ADH Y CrA. Enlargement from A WW Sgr. Enlargement from ADH AA Ser. Identified from sketch provided by Dr. Hoffleit. 35. BV Set. Identified from sketch provided by Dr. Hoffleit. 37. V604 = N2 Aql. Enlargement from same plate. Nova is bright on C HV Very slight variation seen. 39. CG Vul. Variable has large color index. 40. V606 = N1 Aql. Identified from chart in H. Shapley s Nebular Catalogue. 42. OT Aql. Var. 2 not investigated. Enlargement from same plate. 43. OW Aql. Var. 2 not investigated. [Editor s Note: In the process of reproducing these charts, a few points representing nonexistent stars have appeared. It is hoped that these will not affect the usefulness of the charts.]