Explanipedia

Chapter V: Report of the Executive Committee 1997-2000 Open

Robert P. Kraft, F. Pacini, J. Andersen, H. Rickman, Claudio Anguita , et al. · 2001

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Revision and Calibration of MK Luminosity Classes for Cool Giants by<i>Hipparcos</i>Parallaxes Open

Philip C. Keenan, C. Barnbaum · 1999

The Hipparcos parallaxes of cool giants are utilized in two ways in this paper. First, a plot of reduced parallaxes of stars brighter than 6.5, as a function of spectral type, for the first time separates members of the clump from stars in…

The Spectrum Near Maximum Light of the Unusual R Coronae Borealis Variable DY Persei Open

Philip C. Keenan, C. Barnbaum · 1997

DY Per was confirmed photometrically as an R CrB variable by Alksnis in 1994. Spectra near maximum light show the high-speed ejection of matter (sodium at -174 km/sec in DY Per) characteristic of many of these variable stars. Moderate hydr…

Revised MK spectral classification of the red carbon stars Open

Philip C. Keenan · 1993

The spectral classification of the red carbon stars has been brought into the Revised MK system by combining some of the features of the old R, N, and C classifications, as modified by Yamashita, and adding numerical abundance indices. The…

Spectral Classification of Peculiar Red Giants Open

Philip C. Keenan · 1993

Among field stars recent work includes development of classification notation of the strong-CN stars, and the recognition that the barium star with weak CN (HD 130255) may actually be a dwarf barium star. The now established presence of we…

Is the spectral type of the sun constant? Open

Philip C. Keenan · 1991

The spectral type of the whole sun was monitored from August 25, 1988 through October 2, 1990. No changes as large as half a spectral subdivison were detected. The spectral type remained at G2 V.

Spectral types and their uses Open

Philip C. Keenan · 1987

The principles involved in setting up any viable system of spectral classification are discussed. Their application is illustrated by reviewing the essential features of the original MK system of two dimensions and its extension to additio…

Recognition and classification of strong-CN giants Open

Philip C. Keenan, S. B. Yorka, O. C. Wilson · 1987

Fifty of the stars designated as super-metal-rich by Spinrad and Taylor (1969) are classified here on the Revised MK System. Positive CN indices are assigned in recognition of the characteristic excesses of carbon and nitrogen in their atm…

Spectral types and luminosities of supergiants in open clusters Open

Philip C. Keenan, Ronald E. Pitts · 1985

Revised MK spectral types of supergiants and bright giants in open clusters are combined with published cluster moduli to calibrate the luminosity classes in terms of visual absolute magnitudes.

The MK Classification and Its Calibration Open

Philip C. Keenan · 1985

I have been asked to describe the system of spectral classification as it has developed from the original Yerkes Atlas (Morgan, Keenan, Kellman, 1943) until to-day. I use the word “developed” because any system that is to remain useful mus…

Problems in the temperature classification of the red giant stars Open

Philip C. Keenan · 1982

Effective temperatures determined by Tsuji (1981) by the infrared-flux method were shown by him to remain nearly constant in the range M0 to M2. It is easily shown that this is not due to any luminosity effect in the spectral types. Rather…

Changing Emphases in Spectral Classification Open

Philip C. Keenan · 1979

The definitions and general principles of the MK system given in the statement by Dr. Morgan, which Dr. McCarthy has read to you, are an expression of my views also. It is mainly in specifying the MK domains that modifications are necessar…

The Problem of Spectral Classification of Stars in the Sequence S-SC-C Open

P. C. Boeshaar, Philip C. Keenan · 1979

The sequence of stars starting with type S and extending through the SC stars into the red carbon stars are brought into the following revised system of classification: In this table X stands for the temperature type and the number to the …

A More Accurate HR Diagram for the Cooler Stars Open

Philip C. Keenan · 1978

Even if we confine ourselves to the classical HR diagram, postponing the transformation of spectral types and visual absolute magnitudes into basic physical variables, there are several ways to choose the data. If, for example, we want the…

45. Spectral Classifications and Multi-Band Colour Indices (Commissions des Classifications Spectrales et Indices de Couleur à Plusieurs Bandes) Open

C. Jaschek, E. K. Kharadze, A. P. Cowley, B. Hauck, W. Iwanowska , et al. · 1976

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Effects of Heavy-Element Abundance on Classification of G-Type Giants Open

Philip C. Keenan · 1976

Five stars, including ζ Cyg, which had been classified as G6 II to G8 II bright giants, were found by O. C. Wilson to have K-line luminosities close to those of class III giants. These stars show enhancement of the lines of Ba II and other…

Is There NbO in S-Type Stars? Open

Dorothy N. Davis, Philip C. Keenan · 1969

Semiregular Red Variables with High Velocities and Balmer Emission. Open

Philip C. Keenan, Warren Melvin Young · 1964

Spectrograms taken for the classification of red variable stars revealed one, CZ Del, which has one of the largest radial velocities yet observed for a semi- regular variable of class SRb (and spectral type M or S). In the General Catalogu…

Absolute magnitude of the Mira variable X Monocerotis. Open

Philip C. Keenan · 1959

The sharpness of the stellar absorption lines in the spectra of the Mira variables allows their interstellar D-lines to be observed if their peculiar radial velocities exceed 30 to 40 km/sec. X Mon is a particularly favorable case, since i…

Luminosity classification of long-period variable stars. Open

Philip C. Keenan · 1957

Search Bar to Enter New Query quick field: Author First Author Abstract Year Fulltext Select a field or operator abstract abstract only acknowledgements affiliation arXiv category author count author bibcode bibliographic group bib abbrev,…

On the Spectral Type and Luminosity of VV Cephei Open

Philip C. Keenan, Jon Wright · 1957

Stellar Spectra in the Red and Near Infrared Open

Philip C. Keenan · 1957

The spectrum of R Geminorum at its unusually bright maximum in 1955. Open

Philip C. Keenan, Richard G. Teske · 1956

R Geminorum, which is one of the brightest long-period variables having a nearly pure S-type spectrum, normally reaches a visual magnitude near 7.1 at maximum. In 1955 the maximum occurred early in March, about 20 days ahead of the predict…

The spectrum-luminosity diagram for the high-velocity stars. Open

Philip C. Keenan, Geoffrey Keller · 1951

The position of the giant branch of the high- velocity stars has been determined by means of spectroscopic absolute magnitudes and types. A check on the luminosity scale was furnished by 19 giants and subgiants with apparent magnitudes bet…

Luminosity Characteristics on Low-Dispersion Spectra of Stars of Types M0-M4. Open

Philip C. Keenan, J. J. Nassau · 1946

An Atlas of Stellar Spectra Open

W. W. Morgan, Philip C. Keenan, Edith Kellman · 1943

On the Spectral Type of the Sun Open

W. W. Morgan, Philip C. Keenan · 1939

Note on the Effect of Phase Angle on Lunar Eclipse Photometry Open

Philip C. Keenan · 1930

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