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- Cepheids (5)
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- Cepheids – stars: Population II (1)
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- Stars—individual—V371 Per (1)
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Articles 1 - 30 of 51
Full-Text Articles in Physics
Spectra Of Type Ii Cepheid Candidates And Related Stars, Edward G. Schmidt, Danielle Rogalla, Lauren Thacker-Lynn
Spectra Of Type Ii Cepheid Candidates And Related Stars, Edward G. Schmidt, Danielle Rogalla, Lauren Thacker-Lynn
Edward Schmidt Publications
We present low-resolution spectra for variable stars in the Cepheid period range from the ROTSE-I Demonstration Project and the All Sky Automated Survey, some of which were previously identified as type II Cepheid candidates. We have derived effective temperatures, gravities, and metallicities from the spectra. Based on this, three types of variables were identified: Cepheid strip stars, cool stars that lie along the red subgiant and giant branch, and cool main-sequence stars. Many fewer type II Cepheids were found than expected and most have amplitudes less than 0.4 mag. The cool variables include many likely binaries as well as intrinsic …
The Double-Mode Cepheid V371 Persei Redux, Edward G. Schmidt
The Double-Mode Cepheid V371 Persei Redux, Edward G. Schmidt
Edward Schmidt Publications
A metallicity of [Fe/H] = –0.05 to –0.40 was derived from four spectra of the peculiar beat Cepheid V371 Per. This conflicts with previous estimates ranging from –0.7 to –1.0 based on the period ratio. It is suggested that the discrepancy may be resolved by assuming near solar metallicity but a low mass. This is in accord with a suggestion by Sandage and Tammann that the AHB3 (or BL Her) stars are Population I analogs of short-period type II Cepheids. Further pulsational modeling is needed to clarify the status of this star and to understand the AHB3 stars.
V371 Per — A Thick-Disk, Short-Period F/1o Cepheid, P. Wils, A. A. Henden, S. Kleidis, Edward G. Schmidt, D. L. Welch
V371 Per — A Thick-Disk, Short-Period F/1o Cepheid, P. Wils, A. A. Henden, S. Kleidis, Edward G. Schmidt, D. L. Welch
Edward Schmidt Publications
V371 Per was found to be a double-mode Cepheid with a fundamental mode period of 1.738 days, the shortest among Galactic beat Cepheids, and an unusually high period ratio of 0.731, while the other Galactic beat Cepheids have period ratios between 0.697 and 0.713. The latter suggests that the star has a metallicity [Fe/H] between −1 and −0.7. The derived distance from the Galactic plane places it in the thick disk or the Halo, while all other Galactic beat Cepheids belong to the thin disk. There are indications from historical data that both the fundamental and first overtone periods have …
Photometry Of Type Ii Cepheid Candidates From The Northern Part Of The All Sky Automated Survey, Edward G. Schmidt, Brian Hemen, Danielle Rogalla, Lauren Thacker-Lynn, University Of Nebraska - Lincoln
Photometry Of Type Ii Cepheid Candidates From The Northern Part Of The All Sky Automated Survey, Edward G. Schmidt, Brian Hemen, Danielle Rogalla, Lauren Thacker-Lynn, University Of Nebraska - Lincoln
Edward Schmidt Publications
We have obtained VR photometry of 282 Cepheid variable star candidates from the northern part of the All Sky Automated Survey (ASAS). These together with data from the ASAS and the Northern Sky Variability Survey (NSVS) were used to redetermine the periods of the stars. We divided the stars into four groups based on location in a plot of mean color, (V − R), versus period. Two of the groups fell within the region of the diagram containing known type II Cepheids and yielded 14 new highly probable type II Cepheids. The properties of the remaining stars in these two …
Mining Sky Surveys For Astrophysically Interesting Variable Stars: The Cepheid Period Range, Edward G. Schmidt
Mining Sky Surveys For Astrophysically Interesting Variable Stars: The Cepheid Period Range, Edward G. Schmidt
Edward Schmidt Publications
We have undertaken a project to discover new type II Cepheids in two large-area sky surveys. However, most of the candidates from the surveys differ from type II Cepheids in their amplitude and period distributions and they form a separate, cooler sequence relative to the Cepheids in a temperature-gravity plot. We refer to these objects as "Cepheid-lke" stars. Many exhibit unstable pulsation which we illustrate with representative light curves.
Photometry Of Type Ii Cepheid Candidates From The Rotse-I Demonstration Project, Edward G. Schmidt, Shawn Langan, Danielle Rogalla, Lauren Thacker-Lynn
Photometry Of Type Ii Cepheid Candidates From The Rotse-I Demonstration Project, Edward G. Schmidt, Shawn Langan, Danielle Rogalla, Lauren Thacker-Lynn
Edward Schmidt Publications
We have obtained VR photometry of 205 Cepheid variable star candidates that were discovered in a small section of the Northern Sky Variability Survey. Given their locations and apparent magnitudes, any stars in this sample that are Cepheids are very likely to be type II Cepheids. On the basis of the regularity of variation, revised periods, light-curve morphology, slope of the color-magnitude relation, and color, we have identified 97 probable Cepheids and 17 possible Cepheids. While some of the photometric properties, particularly the colors, are consistent with the identification of these stars as Cepheids, the amplitudes are small compared to …
The Spectra Of Type Ii Cepheids. Ii. The Hα Line In Intermediate-Period Stars, Edward G. Schmidt, Shawn Langan, Kevin M. Lee, Dale Johnston, Peter R. Newman, Stephanie A. Snedden
The Spectra Of Type Ii Cepheids. Ii. The Hα Line In Intermediate-Period Stars, Edward G. Schmidt, Shawn Langan, Kevin M. Lee, Dale Johnston, Peter R. Newman, Stephanie A. Snedden
Edward Schmidt Publications
We present 98 Hα profiles for 21 pulsating variable stars with periods from 3 to 8 days. The strength, depth, and shape of Hα vary throughout the cycles of the stars in a way consistent with the temperature changes. Otherwise, they are quite uniform among all the stars, with a single exception. In FM Del, Hα is weaker and has a smaller central depth than in the other stars. This and the wavelength shifts of the core are attributed to incipient emission. The differential velocity of Hα relative to the metal lines is less than 25 km s-1 for …
The Spectra Of Type Ii Cepheids. I. The Hα Line In Short-Period Stars, Edward G. Schmidt, Kevin M. Lee, Dale Johnston, Peter R. Newman, Stephanie A. Snedden
The Spectra Of Type Ii Cepheids. I. The Hα Line In Short-Period Stars, Edward G. Schmidt, Kevin M. Lee, Dale Johnston, Peter R. Newman, Stephanie A. Snedden
Edward Schmidt Publications
We present 88 Hα profiles for 24 pulsating variable stars with periods between 1 and 3 days in order to explore the behavior of this line in type II as compared with classical Cepheids. Surprisingly, large velocity differences were found between Hα and the metal lines in some type II Cepheids. Strong emission was observed in three stars, VZ Aql, NW Lyr, and V439 Oph, while line filling by incipient emission is present in seven others. All of the stars with emission and most with incipient emission belong to Diethelm's AHB2 class, and the emission is associated with the secondary …
The Blazhko Effect Of The Rr Lyrae Star Gv Andromedae, Kevin M. Lee, Edward G. Schmidt, Shawn T. Langan
The Blazhko Effect Of The Rr Lyrae Star Gv Andromedae, Kevin M. Lee, Edward G. Schmidt, Shawn T. Langan
Edward Schmidt Publications
We have obtained 462 new V and R observations of the RR Lyrae star GV Andromedae. Our data set is consistent with a primary period of 0.528092 days; however, the light curve of GV And cannot be well described by a single period. We conclude that GV And demonstrates the Blazhko effect with a Blazhko period of approximately 32 days.
The Intermediate-Period Cepheid Strip Stars, Edward G. Schmidt
The Intermediate-Period Cepheid Strip Stars, Edward G. Schmidt
Edward Schmidt Publications
To explore the population of variable stars that fall between RR Lyrae stars and classical Cepheids, we have obtained extensive photometric observations for 56 stars with periods between 0.6 and 1.0 days. For these stars and an additional 10, we have examined the form and stability of the light curves to explore the variety of types of stars in this period regime. We conclude that the majority of the sample are Bailey type ab RR Lyrae stars. However, a surprising number that possibly exhibit the Blazhko effect are found. There are a half-dozen other stars that do not appear to …
The Blazhko Effect Of The Rr Lyrae Star Dr Andromedae, Kevin M. Lee, Edward G. Schmidt
The Blazhko Effect Of The Rr Lyrae Star Dr Andromedae, Kevin M. Lee, Edward G. Schmidt
Edward Schmidt Publications
We have obtained 551 new V and R observations of the RR Lyrae star DR Andromedae. Our data set is consistent with a primary period of 0.563118 days; however, the light curve of DR And cannot be well described by a single period. We conclude that DR And demonstrates the Blazhko effect with a Blazhko period of approximately 57.5 days.
The Blazhko Effect Of The Rr Lyrae Star Fm Persei, Kevin M. Lee, Edward G. Schmidt
The Blazhko Effect Of The Rr Lyrae Star Fm Persei, Kevin M. Lee, Edward G. Schmidt
Edward Schmidt Publications
We have obtained 615 new V and R observations of the RR Lyrae star FM Per. A period search identified a primary period of 0.489256 days; however, the light curve of FM Per cannot be well described by a single period. We conclude that FM Per demonstrates the Blazhko effect with a Blazhko period of approximately 122 days.
The Rr Lyrae Star V442 Herculis: An Extreme Case Of Light-Curve Modulation, Edward G. Schmidt, Kevin M. Lee
The Rr Lyrae Star V442 Herculis: An Extreme Case Of Light-Curve Modulation, Edward G. Schmidt, Kevin M. Lee
Edward Schmidt Publications
We have obtained photometric observations of the peculiar RR Lyrae star V442 Her during six observing seasons spanning an elapsed time of nearly 9 years. The period has undergone two large, abrupt changes in the past 5 years. Although light-curve modulation is fairly common among RR Lyrae stars, the modulation of the light curve of V442 Her is highly unusual for its large amplitude, long period, extreme alterations in light-curve shape, and large period changes.
Stars Classified As Constant In The General Catalogue Of Variable Stars, Ii, Edward G. Schmidt
Stars Classified As Constant In The General Catalogue Of Variable Stars, Ii, Edward G. Schmidt
Edward Schmidt Publications
Photometric observations have been made of 36 stars classified as CST or CST: in the General Catalogue of Variable Stars. Six of these stars are found to vary and three others were deemed possible variables. Of the certain variables, two (MR Her and TY Sge) are red pulsators, one (V1585 Cyg) is a rapid irregular variable, one is apparently a short period Cepheid-strip star (V432 Oph), one is an eclipsing binary (AQ Boo), and one is of uncertain type (V351 Cyg). The stars we have observed as MR Her and TY Sge are the same ones which were identified on …
The Behlen Observatory Variable Star Survey, Iv, Edward G. Schmidt, Anil Seth
The Behlen Observatory Variable Star Survey, Iv, Edward G. Schmidt, Anil Seth
Edward Schmidt Publications
Finding charts, accurate coordinates, and light curves are presented for 106 variable stars including 6 which are newly discovered. Parameters descriptive of the light curves are tabulated including periods for 16 stars which lacked them. The periods from the General Catalog of Variable Stars for ten stars were found to be seriously in error. The classification of the stars is discussed. Revisions or refinements of the classifications from the General Catalogue of Variable Stars are suggested for 20 stars and classifications are given for 7 which were previously unclassified. 15%-23% of the Bailey type ab RR Lyrae stars show scatter …
Far-Ultraviolet Stellar Photometry: Fields Centered On Ρ Ophiuchi And The Galactic Center, Edward G. Schmidt, George R. Carruthers
Far-Ultraviolet Stellar Photometry: Fields Centered On Ρ Ophiuchi And The Galactic Center, Edward G. Schmidt, George R. Carruthers
Edward Schmidt Publications
Far-ultraviolet photometry is presented for 121 objects in a 20" diameter field centered on ρ Oph and for 649 objects in a field covering the Galactic center. Broadband magnitudes with effective wavelengths of 1375 Å and 1781 Å are given. The Galactic center field overlaps two fields which were discussed in an earlier paper. Eighty-eight percent of the ultraviolet objects in the ρ Oph field were identified with visible stars using the SIMBAD database, while only 9% of the objects are blends of early-type stars too close together to separate with our resolution. The photometric calibration was studied in detail, …
A Photometric Study Of V508 Cygni, S.N. Goderya, Kam-Ching Leung, Edward G. Schmidt
A Photometric Study Of V508 Cygni, S.N. Goderya, Kam-Ching Leung, Edward G. Schmidt
Edward Schmidt Publications
The Behlen observatory 0.76 m telescope CCD photometer has been used to obtain nearly 700 observations of the short period eclipsing binary V508 Cyg. These observations were done using V and R bandpass filters on 9 nights in 1992. Previously published light elements and the present eight determinations of eclipse timings are used to determine a new epoch and a more accurate orbital period of 0.7796587 days. The photometric observations and solutions which have been obtained with the 1993 version of the Wilson- Devinney model show that V508 Cyg is a W UMa type contact binary system. Analyses give two …
Far-Ultraviolet Stellar Photometry: Fields In Sagittarius And Scorpius, Edward G. Schmidt, George R. Carruthers
Far-Ultraviolet Stellar Photometry: Fields In Sagittarius And Scorpius, Edward G. Schmidt, George R. Carruthers
Edward Schmidt Publications
Far-ultraviolet photometry for 741 objects in a field in Sagittarius centered near M8 and 54 1 objects in a field centered near ζ Scorpii is presented. These data were extracted from electrographic images obtained with two cameras during a shuttle flight in 1991 April/May. The cameras provided band passes with λeff= 1375 Å and λeff= 1781 Å. Synthetic colors show that these bands are sensitive to effective temperature for hot stars. Our measurements were placed on a quantitative far-ultraviolet magnitude scale by convolving the spectra of stars observed by IUE with our cameras' spectral response functions. …
Be Stars In Young Clusters, Shaukat N. Goderya, Edward G. Schmidt
Be Stars In Young Clusters, Shaukat N. Goderya, Edward G. Schmidt
Edward Schmidt Publications
Photometric Hχ and Hβ line indices for 71 B stars in seven galactic clusters are presented. Some stars in three of the clusters were observed at two epochs. Using these data nine Be stars were identified. Three of them were previously detected as emission-line stars, while six do not appear to have been previously recognized as such. Of the 62 stars for which we find no indication of emission, three were previously found to exhibit emission. We find that emission-line objects are absent among the most luminous early B giants.
The Behlen Observatory Variable Star Survey: Finding Charts And Light Curves For The First Ninety-Three Stars, Edward G. Schmidt, Darwin E. Reiswig
The Behlen Observatory Variable Star Survey: Finding Charts And Light Curves For The First Ninety-Three Stars, Edward G. Schmidt, Darwin E. Reiswig
Edward Schmidt Publications
In a previous paper, photometry for the first ninety-three stars in a photometric survey of variable stars was discussed. Finding charts, accurate coordinates, and light curves for those stars are presented here. The reliability of the coordinates from the General Catalogue of Variable Stars is discussed. The magnitude scale of the present photometry is compared with that of the Hubble Space Telescope Guide Star Catalogue.
Far-Ultraviolet Stellar Photometry: A Field In Orion, Edward G. Schmidt, George R. Carruthers
Far-Ultraviolet Stellar Photometry: A Field In Orion, Edward G. Schmidt, George R. Carruthers
Edward Schmidt Publications
Far-ultraviolet photometry for 625 objects in Orion is presented. These data were extracted from electrographic camera images obtained during sounding rocket flights in 1975 and 1982. The 1975 images were centered close to the belt of Orion while the 1982 images were centered ~9° further north. One hundred and fifty stars fell in the overlapping region and were observed with both cameras. Sixty-eight percent of the objects were tentatively identified with known stars using the SIMBAD database while another 24% are blends of objects too close together to separate with our resolution. As in previous studies, the majority of the …
Far-Ultraviolet Stellar Photometry: A Field In Monoceros, Edward G. Schmidt, George R. Carruthers
Far-Ultraviolet Stellar Photometry: A Field In Monoceros, Edward G. Schmidt, George R. Carruthers
Edward Schmidt Publications
Far-ultraviolet photometry of stars in a field in Monoceros in the wavelength rang from 1230 Å to 1600 Å has been carried out using data from an electrographic Schmidt camera carried on a sounding rocket. Ultraviolet magnitudes were extracted for 602 objects in the field. Fifty-eight percent were tentatively identified with visible stars using the SIMBAD data base while another 25% are blends of objects too close together to separate with our resolution. Eleven of the uv objects coincide with parts of the star clusters NGC 2169, NGC 2244, and KGC 2264 in which individual stars cannot be resolved. As …
The Behlen Observatory Variable Star Survey, Paper Iii, Edward G. Schmidt, John R. Chab, Darwin E. Reiswig
The Behlen Observatory Variable Star Survey, Paper Iii, Edward G. Schmidt, John R. Chab, Darwin E. Reiswig
Edward Schmidt Publications
Finding charts, accurate coordinates and light curves are presented for 146 variable stars including three which are newly discovered. Parameters descriptive of the light curves arc tabulated including periods for eight stars which lacked them in the General Catalogue of Variable Stars (the GCVS). GCVS periods of twelve stars were found to be seriously in error. The classification of the stars is discussed. Revisions or refinements of the classifications from the General Catalogue of Variable of Stars are suggested for thirty-one stars. Of the nineteen stars classified as Bailey type c RR Lyrae stars in the General Catalogue of Variable …
Stars Classified As Constant In The General Catalog Of Variable Stars, Edward G. Schmidt, John R. Chab, Darwin E. Reiswig
Stars Classified As Constant In The General Catalog Of Variable Stars, Edward G. Schmidt, John R. Chab, Darwin E. Reiswig
Edward Schmidt Publications
Photometric observations have been made of 16 stars classified as constant, CST or CST:, in the General Catalog of Variable Stars. One star, U Tauri, was found to be a rapid irregular variable and three others may vary at a low level. In two cases, FV Delphini and FP Geminorum, the star identified as the variable on published finding charts is not variable but a nearby star did vary. It is suggested that the wrong stars were marked on the charts but the possibility remains that the variables may have exhibited constancy during earlier observations.
The Behlen Observatory Variable Star Survey: First Results, Edward G. Schmidt
The Behlen Observatory Variable Star Survey: First Results, Edward G. Schmidt
Edward Schmidt Publications
Various light curve parameters are presented for the first 93 objects in a photometric survey of poorly studied variable stars. Stars from the General Catalogue of Variable Stars (GCVS) fainter than tenth magnitude, north of the equator which were classified as pulsating variables (but excluding the long period, semiregular, and irregular variables) were included. It is shown that two parameters, the acuteness and the rise time, are useful for characterizing the light curves. Several criteria are applied to the photometric data to test the classification of the stars. For 26 stars new or improved classifications are suggested. In particular, there …
The Long-Period Field Rr Lyrae Stars, Edward G. Schmidt, Charles G. Loomis, Andrew T. Groebner, Chris T. Potter
The Long-Period Field Rr Lyrae Stars, Edward G. Schmidt, Charles G. Loomis, Andrew T. Groebner, Chris T. Potter
Edward Schmidt Publications
VR light curve3 have been obtained for 16 faint variable stars with periods shorter than 1 day. Although, as expected, most of the light curves are typical of Bailey-type ab RR Lyrae stars, some have slower rises to maximum and flatter tops. Fourier decomposition was performed to further explore these trends. Combining these data with previously published Fourier decompositions of RR Lyrae light curves, we find that the Fourier coefficients are essentially constant for periods shorter than three-quarters of a day for Bailey-type ab RR Lyrae stars but that the amplitude ratios, R (12), R (13), and R (14), decrease …
Two New Short-Period Cepheids, Edward G. Schmidt, Bradley A. Gross
Two New Short-Period Cepheids, Edward G. Schmidt, Bradley A. Gross
Edward Schmidt Publications
The General Catalogue of Variable Stars gives periods of slightly less than three-quarters of a day for the stars NO Cas and CN Tau. However, new photometry demonstrates that their periods are actually 2.6 and 1.8 days, respectively, and they are thus classical Cepheids. Fourier decompositions of their light curves are performed, and they are found to be members of a class of Cepheids with periods less than three days which may be related to the s-Cepheids. These two stars represent the shortest and longest known members of this class and thus are very useful in defining its properties in …
Hr Aurigae: An Active Binary ?, Charles G. Loomis, Edward G. Schmidt
Hr Aurigae: An Active Binary ?, Charles G. Loomis, Edward G. Schmidt
Edward Schmidt Publications
Photometric and spectral observations of the variable star HR Aurigae are presented. Based on these data we conclude that this star, previously regarded as a type II Cepheid, is, in fact, an active binary.
The Period-Decline-Rate Relation For Pulsating Stars, Edward G. Schmidt, Kathryn H. Wiese
The Period-Decline-Rate Relation For Pulsating Stars, Edward G. Schmidt, Kathryn H. Wiese
Edward Schmidt Publications
The relationships between the periods and the rate of decline in V and R for pulsating stars are investigated. It is shown that these relationships are useful for making preliminary estimates of periods for stars with little data. These estimates can then be used to optimize times of further observations.
The Chromosphere Of Beta Cassiopeiae, Terry J. Teays, Edward G. Schmidt, Massimo Fracassini, Laura E. Pasinetti Fracassini
The Chromosphere Of Beta Cassiopeiae, Terry J. Teays, Edward G. Schmidt, Massimo Fracassini, Laura E. Pasinetti Fracassini
Edward Schmidt Publications
We have carried out high-resolution, long-wavelength IUE observations and ground-based photometry of the δ Scuti star β Cas. The ground-based observations were used together with previous results of Antonello et al. to ensure that the IUE observations were correctly phased relative to the photometric variation. Fluxes for the emission core of the Mg II k λ2796 line were obtained from the ultraviolet spectra over several cycles in 1986 and 1987. We found that there is an increase in the emission during part of the cycle but it occurs near minimum light in contrast to another δ Scuti star, ρ Pup, …