A Plane-Grating Spectrograph for the Red and Infra-Red Regions of Stellar Spectra

Abstract

view Abstract Citations (4) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Plane-Grating Spectrograph for the Red and Infra-Red Regions of Stellar Spectra Merrill, Paul W. Abstract A brief history of the use of gratings for stellar spectrographs is included in the intro- duction. Description of spectrograph-The optical parts consist of a reflecting slit; a 2~-rnch telephoto collimator lens of 4° inches equivalent focal length; a Jacomini plane grating having 600 lines per millimeter; and interchangeable camera lenses of various focal lengths. The mechanical design is described by Mr. Nichols. The main casting, of aluminum alloy, is in the form of a trussed V with a boxlike extension and is very rigid. It is supported in a tubular steel cradle in such a manner as to eliminate cramping and distortion. Miscellaneous results-In the yellow and red regions numerous lines may be studied to advantage. In spectra of early type these include the detached D lines and emission Ha, ifiustrated in Plate VIII. In K and M spectra certain calcium lines show a strong absolute-magnitude effect. Mr. Sanford has used this spectrograph to extend his radial-velocity determinations of N-type stars. Miss Burwell gives data indicating the accuracy of measurement of radial velocities in stars of classes G-M. Plate IX shows the spectrum of Y Canum Venaticorum, class N3, from X 6800 to X 7650. The instru- ment promises tq be useful in the infra-red as far as X 8700. Of special interest are the (nebular) forbidden Oii multiplet near X 7325, the Oi triplet XX 7772-7774-7775, and the strong Caii triplet XX 8498, 8542, 8662. Numerous Ti lines near X 8400 are strong in the spectrum of o Ceti Publication: The Astrophysical Journal Pub Date: October 1931 DOI: 10.1086/143338 Bibcode: 1931ApJ....74..188M full text sources ADS | Related Materials (1) Reprint: 1931CMWCI.432....1M