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Photometric Study of RX Cephei
Photoelectric observations of RX Cephei from Zsoldas and McAdam (1993)and the authors, and long term visual observations from Schmude and theAAVSO were analyzed. RX Cep, whose variability has been questioned,appears to have become 0.15 magnitude brighter between 1990 and 2000.There is also some evidence of a 350-day period. The B-V color index ofthis star may also be calculated as 1.12+/-0.04.
| The Chemical Compositions of the SRD Variable Stars. III. KK Aquilae, AG Aurigae, Z Aurigae, W Leo Minoris, and WW Tauri
Chemical compositions are derived from high-resolution spectra for fivefield SRd variables. These supergiants not previously analyzed are shownto be metal poor: KK Aql with [Fe/H]=-1.2, AG Aur with [Fe/H]=-1.8, ZAur with [Fe/H]=-1.4, W LMi with [Fe/H]=-1.1, and WW Tau with[Fe/H]=-1.1. Their compositions are, except for two anomalies, identicalto within the measurement errors to the compositions of subdwarfs,subgiants, and less evolved giants of the same [Fe/H]. One anomaly is ans-process enrichment for KK Aql, the first such enrichment reported foran SRd variable. The second and more remarkable anomaly is a stronglithium enrichment for W LMi, also a first for field SRd variables. TheLi I λ6707 profile is not simply that of a photospheric line butincludes strong absorption from redshifted gas, suggesting, perhaps,that lithium enrichment results from accretion of Li-rich gas. Thispotential clue to lithium enrichment is discussed in light of variousproposals for lithium synthesis in evolved stars.
| Is RX Cep a Variable Star?
Not Available
| The Chemical Compositions of the SRD Variable Stars. II. WY Andromedae, VW Eridani, and UW Librae
Chemical compositions are derived from high-resolution spectra for threestars classed as SRd variables in the General Catalogue of VariableStars. These stars are shown to be metal-poor supergiants: WY And with[Fe/H]=-1.0, VW Eri with [Fe/H]=-1.8, and UW Lib with [Fe/H]=-1.2. Theircompositions are identical to within the measurement errors to thecompositions of subdwarfs, subgiants, and less evolved giants of thesame [Fe/H]. The stars are at the tip of the first giant branch or inthe early stages of evolution along the asymptotic giant branch (AGB).There is no convincing evidence that these SRd variables areexperiencing thermal pulsing and the third dredge-up on the AGB. The SRdvariables appear to be at the cool limit of the sequence of RV Taurivariables.
| The Chemical Compositions of the SRd Variable Stars. I. XY Aquarii, RX Cephei, AB Leonis, and SV Ursae Majoris
Chemical compositions are derived from high-resolution spectra for fourstars classed as SRd variables in the General Catalogue of VariableStars. Two stars-XY Aquarii and RX Cephei-are of solar metallicity andmost likely not variable stars. Their spectroscopic effectivetemperatures and surface gravities correspond to the spectral types G0 Vfor XY Aqr and G8 III for RX Cep. Two stars are undisputed variables andshown here to be metal-poor supergiants: AB Leonis with [Fe/H] ~=-1.6and SV Ursae Majoris with [Fe/H] ~=-1.4. The metallicities and highradial velocities show them to be halo stars.
| Professional-amateur collaboration in variable star research: V. Observations of yellow semi-regular variables
Not Available
| The computerisation of the Variable Star Section records
Since its formation in 1890, the Association's Variable Star Section(VSS) has collected about two million variable star observations fromits members. In spite of the fact that these records form a potentiallyvaluable source of data for research, many of them have never beenanalysed or published. The great bulk of the observations consists ofvisual magnitude estimates recorded on hand-written report forms. Since1978, a lot of work has been carried out 'behind the scenes' in the VSSin implementing a computer system to automate the processing. Thepurpose of this paper is to give an account of this work.
| The real nature of RX Cephei
Not Available
| What is RX Cephei?
Not Available
| The Perkins catalog of revised MK types for the cooler stars
A catalog is presented listing the spectral types of the G, K, M, and Sstars that have been classified at the Perkins Observatory in therevised MK system. Extensive comparisons have been made to ensureconsistency between the MK spectral types of stars in the Northern andSouthern Hemispheres. Different classification spectrograms have beengradually improved in spite of some inherent limitations. In thecatalog, the full subclasses used are the following: G0, G5, G8, K0, K1,K2, K3, K4, K5, M0, M1, M2, M3, M4, M5, M6, M7, and M8. Theirregularities are the price paid for keeping the general scheme of theoriginal Henry Draper classification.
| Catalog of Indidual Radial Velocities, 0h-12h, Measured by Astronomers of the Mount Wilson Observatory
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJS...19..387A&db_key=AST
| Photoelectric Observations of RR Lyrae Stars.
Abstract image available at:http://adsabs.harvard.edu/abs/1959ApJ...130..539S
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