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Astrophysics and Astronomy

Tennessee State University

2001

Articles 1 - 7 of 7

Full-Text Articles in Physical Sciences and Mathematics

Chromospherically Active Stars. Xx. The Giant Single-Lined Binary Hd 161570, Francis C. Fekel, Gregory W. Henry, Stephen M. Henry Dec 2001

Chromospherically Active Stars. Xx. The Giant Single-Lined Binary Hd 161570, Francis C. Fekel, Gregory W. Henry, Stephen M. Henry

Information Systems and Engineering Management Research Publications

Spectroscopy of HD 161570 shows it to be a single-lined spectroscopic binary with a period of 45.623 days and a nearly circular orbit. The primary star has spectral type G7 III, and the secondary is most likely a G or K dwarf. A high-resolution spectrum of the 3950 Å region confirms that the primary has Ca II H and K emission lines. The logarithm of the giant's lithium abundance is less than 0.9, indicating that it is not lithium-rich. From photometric observations covering six seasons, we detected periodic short-term light variability with an amplitude ranging from 0.02 to 0.04 mag. …

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No Planet For Hd 166435, Didier Queloz, Gregory W. Henry, Jean-Pierre Sivan, Sallie L. Baliunas, Jean-Luc Beuzit, Robert A. Donahue, Michel Mayor, Dominique Naef, Christian Perrier, Stephane Udry Nov 2001

No Planet For Hd 166435, Didier Queloz, Gregory W. Henry, Jean-Pierre Sivan, Sallie L. Baliunas, Jean-Luc Beuzit, Robert A. Donahue, Michel Mayor, Dominique Naef, Christian Perrier, Stephane Udry

Information Systems and Engineering Management Research Publications

The G0 V star HD 166435 has been observed by the fiber-fed spectrograph ELODIE as one of the targets in the large extra-solar planet survey that we are conducting at the Observatory of Haute-Provence. We detected coherent, low-amplitude, radial-velocity variations with a period of 3.7987 days, suggesting a possible close-in planetary companion. Subsequently, we initiated a series of high-precision photometric observations to search for possible planetary transits and an additional series of Ca II H and K observations to measure the level of surface magnetic activity and to look for possible rotational modulation. Surprisingly, we found the star to be …

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Chromospherically Active Stars. Xix. A Reexamination Of The Variability Of Hd 10909=Uv Fornacis, Francis C. Fekel, Gregory W. Henry, Keinon Brooks, Douglas S. Hall Aug 2001

Chromospherically Active Stars. Xix. A Reexamination Of The Variability Of Hd 10909=Uv Fornacis, Francis C. Fekel, Gregory W. Henry, Keinon Brooks, Douglas S. Hall

Information Systems and Engineering Management Research Publications

We have obtained new spectroscopy and photometry of the K0 IV, chromospherically active, single-lined spectroscopic binary HD 10909. Those observations show that the previously reported orbital and light variability periods are incorrect. HD 10909 has an orbital period of 30.1067 days and an eccentricity of 0.499. Its rotation period of 64.1 days is more than twice as long as its orbital period. The primary is situated near the base of the first-ascent red giant branch. Thus, its asynchronous rotation is likely the result of its recent evolution through the Hertzsprung gap, combined with its relatively long orbital period and high …

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First Results From The Anglo-Australian Planet Search: A Brown Dwarf Candidate And A 51 Peg-Like Planet, Chris G. Tinney, R. Paul Butler, Geoffrey W. Marcy, Hugh R. A. Jones, Alan J. Penny, Steve S. Vogt, Kevin Apps, Gregory W. Henry Apr 2001

First Results From The Anglo-Australian Planet Search: A Brown Dwarf Candidate And A 51 Peg-Like Planet, Chris G. Tinney, R. Paul Butler, Geoffrey W. Marcy, Hugh R. A. Jones, Alan J. Penny, Steve S. Vogt, Kevin Apps, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We report results from the Anglo-Australian Planet Search, a survey for planets around 200 solar-type stars in the southern hemisphere that is being carried out on the 3.9 m Anglo-Australian Telescope. Limiting Doppler precisions of 3 m s-1 have been demonstrated from the first 2.5 years of operation, making this the highest-precision planet search in the southern hemisphere. From these data we report results for two new substellar detections. The first is a 51 Peg-like planet around the star HD 179949 with M sin i = 0.84 MJUP. Photometric study reveals this is not a transiting system. The second is …

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Infrared Spectroscopy Of Symbiotic Stars. Iii. First Orbits For Three S-Type Systems, Francis C. Fekel, Kenneth H. Hinkle, Richard Joyce, Michael F. Skrutskie Apr 2001

Infrared Spectroscopy Of Symbiotic Stars. Iii. First Orbits For Three S-Type Systems, Francis C. Fekel, Kenneth H. Hinkle, Richard Joyce, Michael F. Skrutskie

Information Systems and Engineering Management Research Publications

Infrared radial velocities have been used to derive the first well-determined orbital elements for the cool giants of three symbiotic systems, BF Cyg, V1329 Cyg, and V343 Ser=AS 289. Periods found for BF Cyg and V1329 Cyg from the radial velocity data are in good agreement with periods previously determined for their light variations, and the orbits are circular. Masses for the components of BF Cyg and V1329 Cyg were determined by combining our orbital elements for the cool giants with elements for their hot stars. BF Cyg and V1329 Cyg are shown to be detached binary systems. The third …

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Long‐Term Vri Photometry Of Small‐Amplitude Red Variables. I. Light Curves And Periods, John R. Percy, Joseph B. Wilson, Gregory W. Henry Jan 2001

Long‐Term Vri Photometry Of Small‐Amplitude Red Variables. I. Light Curves And Periods, John R. Percy, Joseph B. Wilson, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We report up to 5000 days of VRI photometry, from a robotic photometric telescope, of 34 pulsating red giants, namely, TV Psc, EG And, Z Psc, RZ And, 4 Ori, RX Lep, UW Lyn, η Gem, μ Gem, ψ1 Aur, V523 Mon, V614 Mon, HD 52690, Y Lyn, BC CMi, X Cnc, UX Lyn, RS Cnc, VY UMa, ST UMa, TU CVn, FS Com, SW Vir, 30 Her, α1 Her, V642 Her, R Lyr, V450 Aql, V1293 Aql, δ Sge, EU Del, V1070 Cyg, W Cyg, and μ Cep, as well as a few variable comparison stars. V …

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10 New Γ Doradus And Δ Scuti Stars, Gregory W. Henry, Francis C. Fekel, Anthony B. Kaye, Ann Kaul Jan 2001

10 New Γ Doradus And Δ Scuti Stars, Gregory W. Henry, Francis C. Fekel, Anthony B. Kaye, Ann Kaul

Information Systems and Engineering Management Research Publications

We present high-resolution spectroscopy and precision photometry of five new γ Doradus and five new δ Scuti variables. The five new γ Doradus variables substantially increase the number of confirmed stars of this class. All 10 stars fall in the spectral class range F0–F2, but they are cleanly separated into two groups by their luminosity and photometric periods. However, the period gap between the γ Doradus and δ Scuti stars is becoming very narrow since we confirm that HD 155154 is a γ Doradus star with the shortest periods reported to date (the shortest of its four periods is ∼0.312 …

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