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Tennessee State University

2003

Articles 1 - 9 of 9

Full-Text Articles in Astrophysics and Astronomy

Rotational Velocities Of B, A, And Early‐F Narrow‐Lined Stars, Francis C. Fekel Jul 2003

Rotational Velocities Of B, A, And Early‐F Narrow‐Lined Stars, Francis C. Fekel

Information Systems and Engineering Management Research Publications

Projected rotational velocities for 58 B, A, and early‐F stars have been determined from high‐resolution spectroscopic observations made at Kitt Peak National Observatory with the coudé feed telescope. All the stars are slowly rotating with vsin i<60 km s−1. Because of their low rotational velocities, 15 of the stars have been observed as prospective, early‐type, radial velocity standards.

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Bv Photometry Of Ux Ari In The Period 1987–2002, Vidar Aarum Ulvås, Gregory W. Henry Apr 2003

Bv Photometry Of Ux Ari In The Period 1987–2002, Vidar Aarum Ulvås, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We present 14.3 years of previously unpublished photometric observations of UX Ari. The observations were obtained between 1987.9 and 2002.2 using the T3 0.4-metre Automatic Photoelectric Telescope at Fairborn Observatory and consist of 1228 B band and 1213 V band measurements. The comparison star was 62 Ari. We have analyzed the new data together with previously published photometric observations. The V magnitude shows variations with dominant periods of about 12 and 25 years, where the longest period seems to correspond to an activity cycle. The previously reported anticorrelation between the colour and V magnitude variations is confirmed.

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The Orbit And Pulsation Periods Of The Γ Doradus Variable Hr 6844 (V2502 Ophiuchi), Francis C. Fekel, Gregory W. Henry Apr 2003

The Orbit And Pulsation Periods Of The Γ Doradus Variable Hr 6844 (V2502 Ophiuchi), Francis C. Fekel, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We obtained spectroscopic and photometric observations of the γ Doradus variable HR 6844 (=V2502 Ophiuchi). Radial velocities show that this star is a single-lined binary with a period of 4.4852 days. The primary is an F1 V star, while the secondary is likely an M dwarf. Velocity residuals to a circular orbit have a period of 1.3071 days and an amplitude of ∼3 km s-1. Three periods of light variation were detected, 1.30702, 1.4350, and 0.62286 days. The first period is essentially identical to that found in the radial velocities and has the largest amplitude, a peak-to-peak value of 0.067 …

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Spectroscopy Of Early F Stars: Γ Doradus Candidates And Possible Metallic Shell Stars, Francis C. Fekel, Phillip B. Warner, Anthony B. Kaye Apr 2003

Spectroscopy Of Early F Stars: Γ Doradus Candidates And Possible Metallic Shell Stars, Francis C. Fekel, Phillip B. Warner, Anthony B. Kaye

Information Systems and Engineering Management Research Publications

We obtained high-resolution spectroscopic observations of 34 γ Doradus candidates. From the red-wavelength spectra, we determined spectral classes, radial velocities, and projected rotational velocities. The spectra of seven late A or early F stars show metallic lines that have composite profiles consisting of a narrow component near the center of a broad line, indicating that they may be shell stars or binaries. Several stars, including HD 152896, HD 173977, HD 175337, and HD 195068/9, show large line profile asymmetries. Two stars, HD 11443 (=α Trianguli) and HD 149420, are ellipsoidal variables and not γ Doradus stars. The percentage of binary …

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Seven New Keck Planets Orbiting G And K Dwarfs, R. Paul Butler, Geoffrey W. Marcy, Steve S. Vogt, Debra A. Fischer, Gregory W. Henry, Gregory Laughlin, Jason Wright Jan 2003

Seven New Keck Planets Orbiting G And K Dwarfs, R. Paul Butler, Geoffrey W. Marcy, Steve S. Vogt, Debra A. Fischer, Gregory W. Henry, Gregory Laughlin, Jason Wright

Information Systems and Engineering Management Research Publications

Planetary mass companions orbiting seven nearby G and K dwarfs have been found from the Keck Precision Doppler Survey. A "51 Peg-like" planet orbiting HD 49674 has the smallest mass yet found, M sin i = 0.12 MJ. This system does not transit. A double-planet system orbits HD 37124, with periods of 153 days and 6 yr and minimum masses of 0.91 and 1.70 MJ. Single companions with moderate eccentricity have been found orbiting HD 108874, HD 72659, HD 114729, and HD 145675 with orbital periods ranging from 1.09 to 5.98 yr, yielding minimum masses ranging …

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Multiperiodicity In Five Small‐Amplitude Pulsating Red Giants, John R. Percy, Gurtina Besla, Vince Velocci, Gregory W. Henry Jan 2003

Multiperiodicity In Five Small‐Amplitude Pulsating Red Giants, John R. Percy, Gurtina Besla, Vince Velocci, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We report multiperiodicity in five small‐amplitude pulsating red giants: RZ Ari, V523 Mon, BC CMi, UX Lyn, and FS Com. For each of these stars, two or three periods recur in each season of our 5000 day database of V observations. The periods and their ratios are consistent with low‐order radial pulsation modes. The amplitudes of the modes change significantly on timescales of 1–5 yr; specifically, the amplitudes of the dominant periods vary on timescales of 2000–3500 days. Most often, the amplitudes of the modes in a given star rise and fall in unison.

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A Sub-Saturn Mass Planet Orbiting Hd 3651, Debra A. Fischer, R. Paul Butler, Geoffrey W. Marcy, Steve Vogt, Gregory W. Henry Jan 2003

A Sub-Saturn Mass Planet Orbiting Hd 3651, Debra A. Fischer, R. Paul Butler, Geoffrey W. Marcy, Steve Vogt, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We report precise Doppler velocities of HD 3651 obtained at Lick and Keck Observatories. The velocities reveal evidence of a planetary companion with an orbital period of 62.23 ± 0.03 days, an eccentricity of 0.63 ± 0.04, and a velocity semiamplitude of 15.9 ± 1.7 m s-1. With an assumed mass of 0.79 M☉ for this K0 V star, we derive M sin i = 0.20MJ and a semimajor axis of 0.284 AU. The star is chromospherically inactive, with log R = -5.01, and 10 years of observations at Fairborn Observatory show it to be …

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A Dozen New Γ Doradus Stars, Gregory W. Henry, Francis C. Fekel Jan 2003

A Dozen New Γ Doradus Stars, Gregory W. Henry, Francis C. Fekel

Information Systems and Engineering Management Research Publications

We use new high-dispersion spectroscopic and precise photometric observations to identify 12 new γ Doradus stars. Two of the 12 systems are double-lined binaries that show obvious velocity variability. Five other stars have metallic lines with composite profiles characterized by a narrow feature near the center of each broad component. Spectrograms of the Hα line indicate that all five stars are binaries rather than shell stars. The remaining five stars in our sample are probably single. All 12 stars are photometrically variable with amplitudes between 6 and 87 mmag in Johnson B and periods between 0.3 and 1.2 days. Four …

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A Planetary Companion To Hd 40979 And Additional Planets Orbiting Hd 12661 And Hd 38529, Debra A. Fischer, Geoffrey W. Marcy, R. Paul Butler, Steve Vogt, Gregory W. Henry, Dimitri Pourbaix, Bernard Walp, Anthony A. Misch, Jason T. Wright Jan 2003

A Planetary Companion To Hd 40979 And Additional Planets Orbiting Hd 12661 And Hd 38529, Debra A. Fischer, Geoffrey W. Marcy, R. Paul Butler, Steve Vogt, Gregory W. Henry, Dimitri Pourbaix, Bernard Walp, Anthony A. Misch, Jason T. Wright

Information Systems and Engineering Management Research Publications

We report the detection of three extrasolar planets from the Lick and Keck observatories. The F8 V star HD 40979 has a companion with orbital period P = 263.1 ± 3 days, eccentricity e = 0.25 ± 0.05, and velocity semiamplitude K = 101.2 ± 5.6 m s-1. The inferred semimajor axis is 0.83 AU and M sin i = 3.28MJup. Observations of planetary companions orbiting the G6 V star HD 12661 and the G4 IV star HD 38529 have already been published, and here we report additional, longer period companions for both of these stars. The outer companion to …

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