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Stars, Interstellar Medium and the Galaxy Commons™

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Physics and Astronomy Faculty Publications

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Full-Text Articles in Stars, Interstellar Medium and the Galaxy

Radial-Velocity And Light Variations Of Ir Cephei, Laurence A. Marschall, Michael A. Seeds, Robert J. Davis Sep 1993

Radial-Velocity And Light Variations Of Ir Cephei, Laurence A. Marschall, Michael A. Seeds, Robert J. Davis

Physics and Astronomy Faculty Publications

Radical-velocity observations of the short-period Cepheid, IR Cephei, have been used to derive a complete radial-velocity versus phase curve for the variable, to investigate the presence of a possible binary companion, and to address the question of its membership in the Cepheus OB2 association. The observations are consistent with the absence of a close binary companion and shed doubt on its membership in the association. Photoelectric observations made with the Phoenix 10 Automated Photometric Telescope confirm the single nature of the star. We present simulations to show the effects of an equiluminous companion on the light curve of a Cepheid, …

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Ccd Photometry Of The Old Open Cluster M67, Kent A. Montgomery, Laurence A. Marschall, Kenneth A. Janes Jul 1993

Ccd Photometry Of The Old Open Cluster M67, Kent A. Montgomery, Laurence A. Marschall, Kenneth A. Janes

Physics and Astronomy Faculty Publications

We present a CCD photometric survey of the central one-half degree of the old open cluster, M67, in U, B, V, and I colors to magnitude V=20. Extensive comparison of our photometry with other published datasets shows excellent agreement, indicating that CCD photometry is capable of producing a uniform set of measurements consistent with the photometric system defined primarily by the Landolt standard sequence. The color-magnitude diagram of the cluster shows a well-defined main sequence extending at least to the limit of the photometry at Mv=10.55 and a substantial binary sequence. At least 38% of cluster stars are …

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Photometric And Spectroscopic Observations Of Sn 1990e In Ngc 1035: Observational Constraints For Models Of Type Ii Supernovae, Brian P. Schmidt, Robert P. Kirshner, Rudolph Schild, Bruno Leibundgut, David Jeffery, S. P. Willner, Reynier Peletier, Ann I. Zabludoff, Mark M. Phillips, Nicholas B. Suntzeff, Mario Hamuy, Lisa A. Wells, Chris Smith, Jack A. Baldwin, W. G. Weller, M. Navarette, L. Gonzalez, Alexei V. Filippenko, Joseph C. Shields, Charles C. Steidel, Saul Perlmutter, Carlton R. Pennypacker, Craig K. Smith, Alain C. Porter, Todd A. Boroson, Raylee Stathakis, Russell Cannon, J. Peters, E. Horine, Kenneth C. Freeman, Donna S. Womble, Remington P.S. Stone, Laurence A. Marschall, Andrew C. Phillips, A. Saha, Howard E. Bond Jun 1993

Photometric And Spectroscopic Observations Of Sn 1990e In Ngc 1035: Observational Constraints For Models Of Type Ii Supernovae, Brian P. Schmidt, Robert P. Kirshner, Rudolph Schild, Bruno Leibundgut, David Jeffery, S. P. Willner, Reynier Peletier, Ann I. Zabludoff, Mark M. Phillips, Nicholas B. Suntzeff, Mario Hamuy, Lisa A. Wells, Chris Smith, Jack A. Baldwin, W. G. Weller, M. Navarette, L. Gonzalez, Alexei V. Filippenko, Joseph C. Shields, Charles C. Steidel, Saul Perlmutter, Carlton R. Pennypacker, Craig K. Smith, Alain C. Porter, Todd A. Boroson, Raylee Stathakis, Russell Cannon, J. Peters, E. Horine, Kenneth C. Freeman, Donna S. Womble, Remington P.S. Stone, Laurence A. Marschall, Andrew C. Phillips, A. Saha, Howard E. Bond

Physics and Astronomy Faculty Publications

We present 126 photometric and 30 spectral observation of SN 1990E spanning from 12 days before B maximum to 600 days past discovery. These observations show that SN 1990E was of type II-P, displaying hydrogen in its spectrum, and the characteristic plateau in its light curve. SN 1990E is one of the few SNe II which has been well observed before maximum light, and we present evidence that this SN was discovered very soon after its explosion. In the earliest spectra we identify, for the first time, several N II lines. We present a new technique for measuring extinction to …

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Chromospherically Active Stars Ix Hd 33798 = V390 Aurigae: A Lithium-Rich Rapidly Rotating Single Giant, Francis C. Fekel, Laurence A. Marschall Oct 1991

Chromospherically Active Stars Ix Hd 33798 = V390 Aurigae: A Lithium-Rich Rapidly Rotating Single Giant, Francis C. Fekel, Laurence A. Marschall

Physics and Astronomy Faculty Publications

HD 33798 is a chromospherically active, rapidly rotating, lithium-rich, late-type giant. Analysis of 40 radial velocities indicates no periodic velocity variations, suggesting that the star is single, so its rapid rotation (v sin i = 29 km s-1) is highly unusual. Such rotation is inconsistent with the rotational brake hypothesis of Gray [ApJ, 262, 682 (1982); 347, 1021 (1989)] and the results of Rutten & Pylyser [A&A, 191, 227 (1988)]. Although there are many similarities to the supposed pre-main-sequence star HDE 283572, the lithium abundance and space motion of HD 33798 appears to be in a post-main-sequence phase of …

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Photometry Of The Chromospherically Active Binary Hd 197010, Laurence A. Marschall, Harold L. Nations, B. W. Taylor, T. L. Huard Jul 1991

Photometry Of The Chromospherically Active Binary Hd 197010, Laurence A. Marschall, Harold L. Nations, B. W. Taylor, T. L. Huard

Physics and Astronomy Faculty Publications

For the past several years we have been conducting a study of the spectroscopic and photometric characteristics of a sample X-ray emitting stars from the Einstein Observatory Medium Sensitivity Survey identified as probable binary systems by Fleming (1988) and Fleming, et al.(1989). One of these stars, HD 197010 ( = 1E2038.3-0046 = SAO 144692 = BD -1degree 4025) was discovered to be a short period eclipsing binary by Robb, et al.(1990). The ephemeris he presented was based on observations in 1989 and 1990, but only the 1990 observations included points at eclipse minimum. We report here on first results of …

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Photometry Of The Young Open Cluster Trumpler 37, Laurence A. Marschall, Neil F. Comins, Gary B. Karshner May 1990

Photometry Of The Young Open Cluster Trumpler 37, Laurence A. Marschall, Neil F. Comins, Gary B. Karshner

Physics and Astronomy Faculty Publications

Photoelectric UBV observations of 120 stars in the young open cluster Trumpler 37 are presented, primarily in the magnitude range 10.0<V

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Sao 23229: A New Double-Lined Spectroscopic Eclipsing Binary, Laurence A. Marschall, Robert P. Stefanik, Harold L. Nations, Robert J. Davis Mar 1990

Sao 23229: A New Double-Lined Spectroscopic Eclipsing Binary, Laurence A. Marschall, Robert P. Stefanik, Harold L. Nations, Robert J. Davis

Physics and Astronomy Faculty Publications

The discovery of eclipses of the bright star SAO 23229 (HD 14384; V=6.9; Spectral Type F5 V) by Indiana observer Dan Kaiser was described in a recent article in Sky and Telescope magazine (MacRobert, 1990). Photoelectric observations by H. Landis and D. Williams, reproduced in that article, show eclipses of 0.55 mag depth and period of 2.111 days. No secondary eclipses are reported, leaving open the question of whether the system contains a very dim secondary or whether it consists of two identical stars with an actual period of 4.2 days. We report here observations that favor the latter interpretation. …

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Parenago 1540: A Pre-Main-Sequence Double-Lined Spectroscopic Binary Near The Orion Trapezium, Laurence A. Marschall, Robert D. Mathieu Dec 1988

Parenago 1540: A Pre-Main-Sequence Double-Lined Spectroscopic Binary Near The Orion Trapezium, Laurence A. Marschall, Robert D. Mathieu

Physics and Astronomy Faculty Publications

Spectroscopic and photometric observations of the star Parenago 1540 (V = 11.3), located 10 arcmin west of the Trapezium in Orion, have shown the star to be a pre-main-sequence double-lined spectroscopic binary. Thirty-seven radial-velocity measurements were obtained from which the orbital elements of the binary were determined, in particular an orbital period P = 33.73 + 0.03 days and an eccentricity of e = 0.12 + 0.01. High-dispersion spectra reveal strong Li 6707 A absorption lines in each of the components of P1540. A spectrum at lower dispersion also shows strong Ca II H and K emission lines, not …

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Membership In The Young Cluster Trumpler 37, Laurence A. Marschall, William F. Van Altena Jul 1987

Membership In The Young Cluster Trumpler 37, Laurence A. Marschall, William F. Van Altena

Physics and Astronomy Faculty Publications

Astrometric positions for 1387 stars and proper motions for a subset of 1135 stars brighter than V=15 in a 1.5 degree surrounding the young open cluster Trumpler 37 are presented. Membership probabilities are presented for those stars with measured proper motions, and 486 stars with probabilities of >80% are identified.

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Membership Of The Rosette Nebula Cluster, Ngc 2244, Laurence A. Marschall, William F. Van Altena, Liang-Tai George Chiu Nov 1982

Membership Of The Rosette Nebula Cluster, Ngc 2244, Laurence A. Marschall, William F. Van Altena, Liang-Tai George Chiu

Physics and Astronomy Faculty Publications

Relative proper motions for 287 stars in the region of the young open cluster NGC 2244, located in the Rsette Nebula, have been determined from plates taken with the Yerkes 40-in. and the Allegheny 30-in. refractors. Probabilities of membership based on these proper motions are derived. Because probable members are chosen primarily from kinematic considerations, the sample should show a minimum photometric bias. Differential extinction across the cluster, however, is identified as a complication in the immediate interpretation of the sample in terms of color-magnitude diagrams or luminosity functions.

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Interferometric Studies Of Interstellar Calcium Lines, Laurence A. Marschall, L. M. Hobbs Apr 1972

Interferometric Studies Of Interstellar Calcium Lines, Laurence A. Marschall, L. M. Hobbs

Physics and Astronomy Faculty Publications

Interferometric, photoelectric scans of the interstellar calcium K-lines in the spectra of 65 stars are presented. The scans were obtained with a PEPSIOS spectrometer having a passband with a full half-intensity width of 1.0 kms(-1) or 0.013A. The fivefold improvement in resolution over that used by Adams reveals numerous line components which correspond very well to those of the interstellar sodium lines, apart from frequent differences in relative intensities.

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