NEW VARIABLE STAR, T CORONA. 



Table {continued). 



281 



Date. 



Mag. 



Colour, &c. 



1866. 









Oct. 6 



8 



10 



7-6 

 7-6 



7'5 



Greyish yellow. 

 Yellow. 





14 

 19 



28 



7-5 

 7"7 

 7-8 



Light yellow. 

 Light yellow. 

 Yellow. 





Nov. 6 

 19 



7-9 

 8-3 



Smyth's orange No. 4. 

 Dull ruddy orange. 





It will be seen that the brightness of the star diminished 

 with great rapidity for several days after my first observa- 

 tion, and afterwards more gradually, and that on the 26th 

 of June it had sunk to the 9*7 magnitude. It then re- 

 mained with little change till about the 20th of August, 

 when another rise commenced, and on the 15th of Sep- 

 tember it had attained the 7*8 magnitude. On the loth 

 and 14th of October it was of the 7*5 magnitude, and 

 since the latter date its brightness has again slightly 

 diminished. 



It wiU also be noticed that in the recent observations 

 no mention is made of the blae tinge which formed so 

 striking a feature in the colour of the star for some time 

 after its first appearance. In connexion with this the 

 following extract of a letter from Mr. Huggins, F.R.S., 

 dated October 1 3th, will be interesting to the Members 

 of the Society. Heferring to T Coronse the writer says, 

 "I observed its spectrum on Sept. i6th, 27th, 28th, and 

 October 8th. The bright lines are not now to be dis- 

 tinguished. If they exist they cannot be much, if any, 

 brighter than the parts of the spectrum where they occur. 

 The observation of its spectrum is now very difficult. ^^ 



In the scale of magnitudes I have employed, the light- 

 ratio is 2*512; but the expression in magnitudes of the 

 brightness of a variable star gives a very imperfect idea of 

 the nature and extent of its changes ; and as any specula- 



SER. III. VOL. III. u 



