HEAT OF STARS

Evening Post, Volume CXVIII, Issue 33, 8 August 1934, Page 3

HEAT OF STARS

LIGHT-COLOUR TEST

HIGHER HEATS SUGGESTED

Stars may bo thousands of degrees hotter than scientists have hitherto believed, state's the London "Morning Post." Our o\vn sun is affected, but only to the extent of a few hundred degrees. It is chiefly about the hotter stars that astronomers will have to adjust their ideas.

.These arc some, of the conclusions reached at Greenwich Observatory as the result of the redetermiuation of the "colour standard" oil which the temperatures of all the stars are based. This latest triumph of Greenwich accuracy was announced by Dr. 11. Spencer Jones, the Astronomer Eoyal, when lie made his annual i-cpovt to the Board of Visitors of the Observatory. It was especially opportune, for the chief event in the afternoon's programme was the formal opening of a now 36----inch telescope, which is to be first used for measuring star temperatures. The telescope has been presented at a cost of £15,000, including the necessary building and dome, by Mr. William Johnston Yapp, and the opening ceremony was performed by Sir Bolton Eyres-Monsell, First Lord of the Admiralty. The surface temperatures of stars, it was explained to a representative of the "Morning Post," are estimated by the quality of the light which they predominantly emit. Merely on the strength of their colours, accurately analysed, they can be placed in order of heat. ' That will be the part of tho Johnston Yapp telescope. But if definite temperatures are to be assigned to individual stars measurements must first be made on a standard of artificial "star," the temperature of which is already known. The standard "star" used on this occasion was a special electric lamp. But the most dramatic role in the tests was assigned to an acetylene burner, used as a subsidiary standard. In order to test the difference between the analysis of light in a laboratory and through a telescope the burner was mounted on the roof of one of the observatory buildings and its light examined at night, like that of any other star, through a big telescope a hundred yards or so away. , Describing the new telescope, which ho intended to commemorate tho work of his predecessor, Sir Frank Dyson, Dr. Spencer Jones said that it was forty years since the observatory was last given a big telescope, and never in its 259 years' history had a.big telescope and the necessary building been simultaneously presented. Tho JohnstonYapp telescope, he said, had a larger light-gathering power than any which the observatory had possessed, and was about as large an instrment ns could bo made to complete advantage in London's climate. It is entirely British made.