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Astrophysics and Astronomy

2004

Series

Information Systems and Engineering Management Research Publications

Articles 1 - 10 of 10

Full-Text Articles in Physical Sciences and Mathematics

A Neptune-Mass Planet Orbiting The Nearby M Dwarf Gj 436, R. Paul Butler, Steve S. Vogt, Geoffrey W. Marcy, Debra A. Fischer, Jason T. Wright, Gregory W. Henry, Gregory Laughlin, Jack J. Lissauer Dec 2004

A Neptune-Mass Planet Orbiting The Nearby M Dwarf Gj 436, R. Paul Butler, Steve S. Vogt, Geoffrey W. Marcy, Debra A. Fischer, Jason T. Wright, Gregory W. Henry, Gregory Laughlin, Jack J. Lissauer

Information Systems and Engineering Management Research Publications

We report precise Doppler measurements of GJ 436 (M2.5 V) obtained at Keck Observatory. The velocities reveal a planetary companion with orbital period of 2.644 days, eccentricity of 0.12 (consistent with zero), and velocity semiamplitude of K = 18.1 m s-1. The minimum mass (M sin i) for the planet is 0.067MJup = 1.2MNep = 21MEarth, making it the lowest mass exoplanet yet found around a main-sequence star and the first candidate in the Neptune-mass domain. GJ 436 (mass = 0.41 M☉) is only the second M dwarf found to harbor a planet, joining the two-planet system around GJ 876. …

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Spectroscopic Orbits Of Potential Interferometric Binaries, Francis C. Fekel, Jocelyn Tomkin Oct 2004

Spectroscopic Orbits Of Potential Interferometric Binaries, Francis C. Fekel, Jocelyn Tomkin

Information Systems and Engineering Management Research Publications

We are obtaining high-resolution, red-wavelength spectra at McDonald and Kitt Peak National Observatory to improve the orbits of known spectroscopic binaries that are potential targets for ground-based optical interferometers. The combination of such observations will produce three-dimensional orbits from which very accurate masses and orbital parallaxes can be obtained for double-lined systems. This spectroscopic program will be expanded and placed on the menu of the 2 meter Automatic Spectroscopic Telescope of Tennessee State University once it commences routine operation. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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Managing The Operations Of The Tsu 2-M Automatic Spectroscopic Telescope, Joel A. Eaton, Michael Williamson Oct 2004

Managing The Operations Of The Tsu 2-M Automatic Spectroscopic Telescope, Joel A. Eaton, Michael Williamson

Information Systems and Engineering Management Research Publications

Tennessee State University has built and is now operating a completely automatic 2-m telescope for highdispersion spectroscopy. This system consists of an alt-azimuth f/8 Cassegrain telescope, housed in an enclosure with a roll-off roof, coupled to a white-pupil echelle spectrograph through a fiber-optic cable. We discuss managing this facility over the Internet with emphasis on 1) the configuration of the control system, 2) logging, 3) troubleshooting and quality control, 4) updating the target lists, and 5) archiving and handling the data.

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Sb9: The Ninth Catalogue Of Spectroscopic Binary Orbits, Dimitri Pourbaix, Andrei A. Tokovinin, Alan H. Batten, Francis C. Fekel, William I. Hartkopf, Hugo Levato, Nidia I. Morrell, Guillermo Torres, Stephane Udry Aug 2004

Sb9: The Ninth Catalogue Of Spectroscopic Binary Orbits, Dimitri Pourbaix, Andrei A. Tokovinin, Alan H. Batten, Francis C. Fekel, William I. Hartkopf, Hugo Levato, Nidia I. Morrell, Guillermo Torres, Stephane Udry

Information Systems and Engineering Management Research Publications

The Ninth Catalogue of Spectroscopic Binary Orbits (http://sb9.astro.ulb.ac.be) continues the series of compilations of spectroscopic orbits carried out over the past 35 years by Batten and collaborators. As of 2004 May 1st, the new Catalogue holds orbits for 2386 systems. Some essential differences between this catalogue and its predecessors are outlined and three straightforward applications are presented: (1) completeness assessment: period distribution of SB1s and SB2s; (2) shortest periods across the H-R diagram; (3) period-eccentricity relation.

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Photospheric Temperature Measurements In Young Main Sequence Stars, Katia Biazzo, Antonio Frasca, Gregory W. Henry, S. Catalano, Ettore Marilli Jul 2004

Photospheric Temperature Measurements In Young Main Sequence Stars, Katia Biazzo, Antonio Frasca, Gregory W. Henry, S. Catalano, Ettore Marilli

Information Systems and Engineering Management Research Publications

As part of our program to study stellar photospheric and chromospheric activity, we have examined several young solar type stars with activity levels intermediate between the Sun and the very active RS CVn binaries. We have analysed contemporaneous spectroscopic data obtained at Catania Observatory (Serra La Nave station, Mt. Etna) and photometric data acquired in the Stromgren bands with an automatic photometric telescope (APT) at Fairborn Observatory (Arizona, USA). Surface inhomogeneities have been detected from the rotational modulation of stellar brightness as well as from the modulation of several photospheric line-depth ratios (LDRs). The presence of chromospheric plage-like regions has …

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Why Do Some Spotted Stars Become Bluer As They Become Fainter?, Vidar Aarum-Ulvås, Gregory W. Henry Jul 2004

Why Do Some Spotted Stars Become Bluer As They Become Fainter?, Vidar Aarum-Ulvås, Gregory W. Henry

Information Systems and Engineering Management Research Publications

Chromospherically active, spotted stars generally become redder as well as fainter when large starspots rotate into view on the stellar disc. However, the RS CVn system UX Ari (a triple-lined system), becomes bluer as it gets fainter. One possible explanation is that hot, bright facular regions accompany the cool, dark photospheric spots of the active component. The bluer flux of the hotter, inactive component does not appear to be sufficient to explain the observed behaviour. We have begun a search for additional chromospherically active stars with a similar relation between colour and brightness, to investigate whether these relations can be …

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Chromospherically Active Stars. Xxiii. The Triple System Hd 7205=Qu Andromedae, Francis C. Fekel May 2004

Chromospherically Active Stars. Xxiii. The Triple System Hd 7205=Qu Andromedae, Francis C. Fekel

Information Systems and Engineering Management Research Publications

HD 7205 is a recently discovered visual binary. The primary star is a chromospherically active, single-lined binary, making the system triple. From spectroscopic observations, the orbit of the primary has a period of 18.01335 days and a moderate eccentricity of 0.197. The primary's spectral type is G8 IV-V. The unseen secondary of the short-period binary is likely an M dwarf, while the visual binary secondary is probably a K3 dwarf. From solar-abundance evolutionary tracks, the primary has a mass of ~1.0 Msolar and an age of about 10. It has evolved off the main sequence and is approaching the base …

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Chromospherically Active Stars. Xxii. Hd 18955, A Massive K Dwarf Binary, Francis C. Fekel, Gregory W. Henry, Frank M. Alston Apr 2004

Chromospherically Active Stars. Xxii. Hd 18955, A Massive K Dwarf Binary, Francis C. Fekel, Gregory W. Henry, Frank M. Alston

Information Systems and Engineering Management Research Publications

HD 18955 is a double-lined spectroscopic binary with a period of 43.3214 days and a high eccentricity of 0.761. The spectral types of the components are K0 V and K2-K3 V. The secondary is a typical early K dwarf, although its minimum mass is greater than canonical values. However, this larger mass is consistent with other early K dwarf, spectroscopic binary results. The primary is anomalous, being substantially underluminous for its radius and mass, which are equal to or slightly greater than solar values. A lack of lithium argues that the components are not pre-main-sequence stars. The large minimum masses …

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Searching For Planets In The Hyades. Iii. The Quest For Short-Period Planets, Diane B. Paulson, Steven H. Saar, William D. Cochran, Gregory W. Henry Mar 2004

Searching For Planets In The Hyades. Iii. The Quest For Short-Period Planets, Diane B. Paulson, Steven H. Saar, William D. Cochran, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We have been using the Keck I High Resolution Spectrograph to search for planetary companions in the Hyades cluster. We selected four stars from this sample that showed significant radial velocity variability on short timescales to search for short-period planetary companions. The radial velocities of these four stars were monitored regularly with the Hobby-Eberly Telescope for approximately 2 months, while sparse data were also taken over ∼4 months: we also obtained near-simultaneous photometric observations with one of the automatic photoelectric telescopes at Fairborn Observatory. For three of the stars, we detect photometric variability with the same period present in the …

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Hd 207651: A Triple System With Δ Scuti And Ellipsoidal Variations But No Γ Doradus Pulsations, Gregory W. Henry, Francis C. Fekel, Stephen M. Henry Mar 2004

Hd 207651: A Triple System With Δ Scuti And Ellipsoidal Variations But No Γ Doradus Pulsations, Gregory W. Henry, Francis C. Fekel, Stephen M. Henry

Information Systems and Engineering Management Research Publications

We examine HD 207651 as a possible example of a star exhibiting both γ Doradus and δ Scuti type pulsations. We find photometric periods of 0.06479 and 0.06337 days with peak-to-peak amplitudes in Johnson B of 21 and 13 mmag, respectively, clearly indicating δ Scuti pulsations. Additional light variation with a period of 0.73540 days and an even larger amplitude of 31 mmag is within the range of γ Doradus pulsation periods but results instead from the ellipticity effect. HD 207651 has a composite spectrum with a weak, narrow absorption line superposed near the center of each broad metal line. …

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