38 



KNOWLEDGE & SCIENTIFIC NEWS. 



[Feuruarv, 1907. 



ASTRONOMICAL. 



By Charles P. Butlek, A.R.C.Sc. (Lond.), F.R.P.S. 



Solar Disturbances and the Corona. 



An interesting paper is cniiinniiiicated to the Astiopliysical 

 Jounuil for Meceniber, 190(1, by F.itlier A. L. Cortie, in which 

 he discusses the relation of certain well-marked features of the 

 corona with areas of distnrbance on the solar surface as evi- 

 denced by various phenomena. That there exists a general 

 connection between the state of disturbance of the sun's 

 surface and immediate surroundings and the form of the 

 coronal appendages is sutTiciently well established. There is 

 a great similarity in type in the photographs of the solar 

 corona as photographed in the years 1.S70, 1882, 1893, and 

 ig05, all of them years of maximum sun-spot activity, marked 

 by many and great outbursts of spots and prominences. A 

 quite different type of corona corresponds to the years of 

 minimum solar activity, as illustrated by the photographs of 

 187S, iS8(), and igoi, while we have also examples of inter- 

 mediate or transition types in the eclipses of 1SS6 and 1896. 

 The uncertainty comes in when we attempt to decide whether 

 the spots or prominences are the more intimately connected 

 with the changes. Careful examination of the Stonyhurst 

 photographs (taken on a large scale) of the solar corona of 

 August 30, 1905, at \'inaro2, Spain, shows that the streamers 

 appear in general to mark the regions of the prominences 

 rather than of the sun spots. The longest streamers, consist- 

 ing of two long wings with an intermediate shorter streamer, 

 extend from latitude ~ 40" to — go" S., quite outside the spot 

 zone, while another streamer is located near the sun's north 

 pole. The fine group of prominences in the north-east quad- 

 rant was manifestly associated with three fine coronal 

 streamers. In the lower corona the complicated structure of 

 arches and vortex rings are seen to be attached to the pro- 

 minences. 



Detailed measurements have been made on several of the 

 photographs in order to determine as accurately as possible 

 the exact area on the sun's surface from which the chief 

 streamers appear to be projected, and comparisons made with 

 other measurements made on the standard series of drawings 

 of the sun at Stonyhurst, thereby enabling the history of the 

 various spots visible before and after the eclipse to be studied. 

 The results apparently confirm the coincidences, and further 

 studies of the eclipse photographs of 1893 giving the same 

 conclusions, the author considers that not only in general is 

 a characteristic type of solar corona associated with sun-spot 

 and prominence activity, but that definite structures in the 

 corona are associated with definite areas of activity of sun 

 spots and faculje. 



Prominences Observed During 190S. 



In l-5ulletin Xo. \TI. of the Kodaikanal Observatory, the 

 Director gives the individual observations of prominences 

 observed during the latter half of igo5 and an abstract sum- 

 mary, showing the mean daily values and zone distribution for 

 the whole year. 



Observations being made on 305 days, the total number of 

 prominences measured was 4757, giving a mean daily frequency 

 of 15-6. 



A very noticeable feature is the slight variation noted in 

 the mean height for each month, the minimum of which is 

 28-4" and the maximum 357", giving a mean for the year 

 of 31-4". 



The distribution with respect to the Solar equator is shown 

 to be very nearly balanced, being 7'8 for each 1 eniisphere. 

 The mean latitudes vary slightly in the two hemispheres, being 

 37'3° for the North and 3S-3° for the South. 



A detailed analysis of the numbers of prominences observed 

 fcr each quarter and half-year in zones of 10' width from 



pole to pole is also included, enabling the prominence record 

 to be compared in dutail with other solar phenomena. 



Observations of Phcebe. 



Professor E. C. Pickering gives a list ol nine additional 

 photographs of Saturn, showing images of the ninth satellite, 

 Phn.bc, which have been obt.iined with the 24inch Bruce 

 telescope at Arequipa during August and September, 1906. 

 The exposures for these plates varied from lo^ to 120 minutes. 

 Reductions of the photographsshowiug the position angles, and 

 distances are given, these varying from 251° and 12'4' on 

 .Xugnst II to joo" and 2'o' on September 17. (Harvard 

 College Observatory ("irciil.ir No. 119.) 



Nova Veiorum. 



During the examination of photographs taken at the Harvard 

 College Observatory with the i-inch Cooke lens, a new object 

 was found in the Constellation Vela, with position as follows : — 

 K.A. = 10 h. 58 m. 20 s. ; Decl. = — 53" srg" (1900). It 

 follows a fifteenth magnitude star by about 2 s., and is 15' 

 south of it. Owing to the small scale of these plates, measure- 

 ments of position and brightness were ditTicult. The object 

 does not appear on any plate taken before December 5, 1905, 

 hut is seen on fourteen plates since that date ; and on July 2, 

 1906, it had again fallen below magnitude ii'2. The greatest 

 brilliancy occurred about Jatui.ary 1, 1900, when the magnitude 

 was 9'72; but during the period covered by the ol)ser\ations 

 the Nova exhibited considerable lluctuations in light, and it 

 seems not impossible that it may again become sufficiently 

 bright for its spectrum to be obtained, but even without such 

 proof there is apparently little doubt that the object observed 

 is actually a Nova. (Harvard College Observatory Circular 

 No. 121.) 



Companion to the Observatory for 1907. 



Except for a fesv minor alterations the present issue of this 

 most useful compendium resembles closely those of previous 

 years. 



The section dealing with variable stars has been slightly 

 re-arranged, this b?ing necessitated by the continued increase 

 in the number of known variables, which now total 574 in 

 M. Loewy's list. The complete list of stars with their places 

 is not now given, and the dates of maxima and mimima of 

 long-period variables are shown in a somewhat different form. 

 These Ephemerides are j^iven in Gi-cnni'icli incait astronomical 

 time, counting from noon to noon, and not from midnight to 

 midnight, as in former years. The range of magnitude is added 

 at the top of each column. 



The occultations of stars by the moon are alsoincreased^in 

 number by the inclusion of stars fainter than 6-8. No diagram 

 of the orbit of Saturn's satellites is given, as their plane passes 

 through the Earth during 1907. 



New Variable Stars. 



The study of the distribution of variable stars by super- 

 posing a negative on a positive of different date has been 

 continued by Miss Leavitt at Harvard College Observatory 

 with very interesting results. From photographs taken with 

 the 24-inch Bruce telescope thirty-one new variables have 

 been discovered, including one in the region of the Pleiades, 

 two near the nebula of Orion, and twenty-eight in the region 

 of the " Southern Cross " and " Coalsack." From the 

 absence of variables in the first group it would appear that 

 the conditions in the vicinity of the Pleiades favour unusual 

 constancy in light, as no other stars were ever suspected of 

 variability, though there are many suspected variables in the 

 other regions examined in this way. 



On photographs taken with the i-inch Cooke lens, covering 

 a region 30° square, and showing stars down to the eleventh 

 magnitude, thirty-six new variables have been discovered, and 

 in addition most of those already known have been re-detected. 

 Six of them belong to the Algol type, and a full discussion of 

 their periods wilFbe given later in the annals. (Harvard 

 College Observatory Circulars Nos. 120, 122.) 



Total Eclipse of the Sun, January 14, 1907, 



Only meagre reports are to hand as to the total solar eclipse 

 which took place on Monday, January 14. In a message from 

 Renter's Agency at Samarkand, it was stated that the eclipse 

 of the sun was observed from a point on the railway between 

 Kuropatkino and Mijulnsk^ja. The first stage of the eclipse 



