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Articles 271 - 300 of 402
Full-Text Articles in Astrophysics and Astronomy
Spectroscopy And Photometry Of The Double-Lined Binary Hd 149420, Francis C. Fekel, Gregory W. Henry
Spectroscopy And Photometry Of The Double-Lined Binary Hd 149420, Francis C. Fekel, Gregory W. Henry
Information Systems and Engineering Management Research Publications
We have used new spectroscopic and photometric observations of HD 149420 to obtain an improved orbital element solution and determine some basic properties of the system. This double-lined binary has an orbital period of 3.39430 days, a circular orbit, and a mass ratio of 0.52. The primary is somewhat evolved, with an A9 IV spectral type, while the secondary is estimated to be an F5: dwarf. The secondary may be synchronously rotating, but the primary is rotating substantially slower than its synchronous velocity. Our photometric observations confirm the light variability and period found by Hipparcos. We determine a photometric period …
The N2k Consortium. Iii. Short-Period Planets Orbiting Hd 149143 And Hd 109749, Debra A. Fischer, Gregory Laughlin, Geoffrey W. Marcy, R. Paul Butler, Steve S. Vogt, John A. Johnson, Gregory W. Henry, Chris Mccarthy, Mark Ammons, Sarah Robinson, Jay Strader, Jeff A. Valenti, Peter R. Mccullough, David Charbonneau, Joshua Haislip, Heather Knutson, Daniel E. Reichart, Padric Mcgee, Berto Monard, Jason T. Wright, Shigeru Ida, Bun'ei Sato, Dante Minniti
The N2k Consortium. Iii. Short-Period Planets Orbiting Hd 149143 And Hd 109749, Debra A. Fischer, Gregory Laughlin, Geoffrey W. Marcy, R. Paul Butler, Steve S. Vogt, John A. Johnson, Gregory W. Henry, Chris Mccarthy, Mark Ammons, Sarah Robinson, Jay Strader, Jeff A. Valenti, Peter R. Mccullough, David Charbonneau, Joshua Haislip, Heather Knutson, Daniel E. Reichart, Padric Mcgee, Berto Monard, Jason T. Wright, Shigeru Ida, Bun'ei Sato, Dante Minniti
Information Systems and Engineering Management Research Publications
We report the detection of two short-period planets discovered at Keck Observatory. HD 149143 is a metal-rich G0 IV star with a planet of M sin i = 1.33MJ and an orbital radius of 0.053 AU. The best-fit Keplerian model has an orbital period, P = 4.072 days, semivelocity amplitude, K = 149.6 m s-1, and eccentricity, e = 0.016 ± 0.01. The host star is chromospherically inactive and metal-rich, with [Fe/H] = 0.26. Based on the Teff and stellar luminosity, we derive a stellar radius of 1.49 R☉. Photometric observations of HD 149143 were carried out using the automated …
Sun In The Spectroscopic Binary Im Pegasi, The Guide Star For The Gravity Probe B Mission, Stephen C. Marsden, Svetlana Berdyugina, Jean-Francois Donati, Joel A. Eaton, Michael H. Williamson, Ilya Ilyin, Debra A. Fischer, Melesio Muñoz, Howard Isaacson, M. I. Ratner, Meïr Semel, Pascal Petit, Brad D. Carter
Sun In The Spectroscopic Binary Im Pegasi, The Guide Star For The Gravity Probe B Mission, Stephen C. Marsden, Svetlana Berdyugina, Jean-Francois Donati, Joel A. Eaton, Michael H. Williamson, Ilya Ilyin, Debra A. Fischer, Melesio Muñoz, Howard Isaacson, M. I. Ratner, Meïr Semel, Pascal Petit, Brad D. Carter
Information Systems and Engineering Management Research Publications
We present the first detection of the secondary of the spectroscopic binary system IM Pegasi (HR 8703), the guide star for the NASA-Stanford relativity gyroscope mission Gravity Probe B. In support of this mission, high-resolution echelle spectra of IM Peg have been obtained on an almost nightly basis. Applying the technique of least-squares deconvolution, we achieve very high signal-to-noise ratio line profiles and detect the orbit of the secondary of the system. Combining almost 700 new radial velocity measurements of both the primary and secondary of the system with previous measurements, we derive improved orbital parameters of the IM Peg …
The N2k Consortium. Ii. A Transiting Hot Saturn Around Hd 149026 With A Large Dense Core, Bun'ei Sato, Debra A. Fischer, Gregory W. Henry, Gregory Laughlin, R. Paul Butler, Geoffrey W. Marcy, Steve Vogt, Peter Bodenheimer, Shigeru Ida, Eri Toyota, Aaron S. Wolf, Jeff A. Valenti, Louis J. Boyd, John A. Johnson, Jason T. Wright, Mark Ammons, Sarah E. Robinson, Jay Strader, Chris Mccarthy, Kok Leong Tah, Dante Minniti
The N2k Consortium. Ii. A Transiting Hot Saturn Around Hd 149026 With A Large Dense Core, Bun'ei Sato, Debra A. Fischer, Gregory W. Henry, Gregory Laughlin, R. Paul Butler, Geoffrey W. Marcy, Steve Vogt, Peter Bodenheimer, Shigeru Ida, Eri Toyota, Aaron S. Wolf, Jeff A. Valenti, Louis J. Boyd, John A. Johnson, Jason T. Wright, Mark Ammons, Sarah E. Robinson, Jay Strader, Chris Mccarthy, Kok Leong Tah, Dante Minniti
Information Systems and Engineering Management Research Publications
Doppler measurements from Subaru and Keck have revealed radial velocity variations in the V = 8.15, G0 IV star HD 149026 consistent with a Saturn-mass planet in a 2.8766 day orbit. Photometric observations at Fairborn Observatory have detected three complete transit events with depths of 0.003 mag at the predicted times of conjunction. HD 149026 is now the second-brightest star with a transiting extrasolar planet. The mass of the star, based on interpolation of stellar evolutionary models, is 1.3 ± 0.1 M☉; together with the Doppler amplitude K1 = 43.3 m s-1, we derive a planet mass M sin i …
System Parameters Of The Transiting Extrasolar Planet Hd 209458b, Robert A. Wittenmyer, William F. Welsh, Jerome A. Orosz, A. B. Schultz, Wayne Kinzel, M. Kochte, Frederick Bruhweiler, David Bennum, Gregory W. Henry, Geoffrey W. Marcy, Debra A. Fischer, R. Paul Butler, Steve Vogt
System Parameters Of The Transiting Extrasolar Planet Hd 209458b, Robert A. Wittenmyer, William F. Welsh, Jerome A. Orosz, A. B. Schultz, Wayne Kinzel, M. Kochte, Frederick Bruhweiler, David Bennum, Gregory W. Henry, Geoffrey W. Marcy, Debra A. Fischer, R. Paul Butler, Steve Vogt
Information Systems and Engineering Management Research Publications
We derive improved system parameters for the HD 209458 system using a model that simultaneously fits both photometric transit and radial velocity observations. The photometry consists of previous Hubble Space Telescope STIS and FGS observations, 12 I-band transits observed between 2001 and 2003 with the Mount Laguna Observatory 1 m telescope, and six Strömgren b + y transits observed between 2001 and 2004 with two of the Automatic Photometric Telescopes at Fairborn Observatory. The radial velocities were derived from Keck HIRES observations. The model properly treats the orbital dynamics of the system and thus yields robust and physically self-consistent solutions. …
A ~7.5 M⊕ Planet Orbiting The Nearby Star, Gj 876*, Eugenio Rivera, Jack J. Lissauer, R. Paul Butler, Geoffrey W. Marcy, Steve Vogt, Debra A. Fischer, Timothy M. Brown, Gregory Laughlin, Gregory W. Henry
A ~7.5 M⊕ Planet Orbiting The Nearby Star, Gj 876*, Eugenio Rivera, Jack J. Lissauer, R. Paul Butler, Geoffrey W. Marcy, Steve Vogt, Debra A. Fischer, Timothy M. Brown, Gregory Laughlin, Gregory W. Henry
Information Systems and Engineering Management Research Publications
High-precision, high-cadence radial velocity monitoring over the past 8 yr at the W. M. Keck Observatory reveals evidence for a third planet orbiting the nearby (4.69 pc) dM4 star GJ 876. The residuals of three-body Newtonian fits, which include GJ 876 and Jupiter-mass companions b and c, show significant power at a periodicity of 1.9379 days. Self-consistently fitting the radial velocity data with a model that includes an additional body with this period significantly improves the quality of the fit. These four-body (three-planet) Newtonian fits find that the minimum mass of companion "d" is m sin i = 5.89 ± …
Five New Multicomponent Planetary Systems, Steve Vogt, R. Paul Butler, Geoffrey W. Marcy, Debra A. Fischer, Gregory W. Henry, Gregory Laughlin, Jason T. Wright, John A. Johnson
Five New Multicomponent Planetary Systems, Steve Vogt, R. Paul Butler, Geoffrey W. Marcy, Debra A. Fischer, Gregory W. Henry, Gregory Laughlin, Jason T. Wright, John A. Johnson
Information Systems and Engineering Management Research Publications
We report Doppler measurements for six nearby G- and K-type main-sequence stars that show multiple low-mass companions, at least one of which has planetary mass. One system has three planets, the fourth triple-planet system known around a normal star, and another has an extremely low minimum mass of 18 M⊕. HD 128311 (K0 V) has two planets (one previously known) with minimum masses (M sin i) of 2.18MJ and 3.21MJ and orbital periods of 1.26 and 2.54 yr, suggesting a possible 2 : 1 resonance. For HD 108874 (G5 V), the velocities reveal two planets (one previously known) having minimum …
Chromospherically Active Stars. Xxv. Hd 144110=Ev Draconis, A Double-Lined Dwarf Binary, Francis C. Fekel, Gregory W. Henry, Ceteka Lewis
Chromospherically Active Stars. Xxv. Hd 144110=Ev Draconis, A Double-Lined Dwarf Binary, Francis C. Fekel, Gregory W. Henry, Ceteka Lewis
Information Systems and Engineering Management Research Publications
New spectroscopic and photometric observations of HD 144110 have been used to obtain an improved orbital element solution and determine some basic properties of the system. This chromospherically active, double-lined spectroscopic binary has an orbital period of 1.6714012 days and a circular orbit. We classify the components as G5 V and K0 V and suggest that they are slightly metal-rich. The photometric observations indicate that the rotation of HD 144110 is synchronous with the orbital period. Despite the short orbital period, no evidence of eclipses is seen in our photometry.
Eleven New Γ Doradus Stars, Gregory W. Henry, Francis C. Fekel, Stephen M. Henry
Eleven New Γ Doradus Stars, Gregory W. Henry, Francis C. Fekel, Stephen M. Henry
Information Systems and Engineering Management Research Publications
We present new high-dispersion spectroscopic and precise photometric observations to identify 11 new γ Doradus variables. Seven of these new γ Doradus stars appear to be single, three are primaries of single-lined binaries, and one has two distant visual companions; none are double-lined or close visual binaries. Several of the stars show spectroscopic line-profile and low-amplitude radial velocity variability indicative of pulsation. All 11 stars are photometrically variable with amplitudes between 8 and 93 mmag in Johnson B and periods between 0.398 and 2.454 days. One star is monoperiodic; the rest have between two and five independent periods. The variability …
Hd 8801: A Unique Single Am Star With Γ Doradus And Δ Scuti Pulsations, Gregory W. Henry, Francis C. Fekel
Hd 8801: A Unique Single Am Star With Γ Doradus And Δ Scuti Pulsations, Gregory W. Henry, Francis C. Fekel
Information Systems and Engineering Management Research Publications
We have discovered the first example of a star pulsating intrinsically with both γ Doradus and δ Scuti frequencies. The star, HD 8801, is an Am metallic-line star that appears to be single. Since the vast majority of Am stars are members of binary systems with periods less than 1000 days and also do not pulsate, HD 8801 possesses a very unusual, if not unique, combination of physical properties. Our photometry, acquired with an automatic telescope at Fairborn Observatory, resolves six independent pulsation periods between 0.048 and 0.404 days. The two longest periods lie within the range of γ Dor …
Chromospherically Active Stars. Xxiv. The Giant, Single-Lined Binaries Hd 37824, Hd 181809, And Hd 217188, Francis C. Fekel, Gregory W. Henry
Chromospherically Active Stars. Xxiv. The Giant, Single-Lined Binaries Hd 37824, Hd 181809, And Hd 217188, Francis C. Fekel, Gregory W. Henry
Information Systems and Engineering Management Research Publications
We have obtained spectroscopy and photometry of three chromospherically active, single-lined spectroscopic binaries, HD 37824 (V1149 Ori), HD 181809 (V4138 Sgr), and HD 217188 (AZ Psc). HD 37824 has a circular orbit with a period of 53.57 days. Its primary is a K0 III star, while the secondary is likely a G or K dwarf. HD 181809 has an orbit with a period of 13.04667 days and a low eccentricity of 0.040. The primary has a spectral type of K0 III-IV, and its secondary is probably an M dwarf. The orbit of HD 217188 has a period of 47.1209 days …
Long Period Variables In The Globular Cluster 47 Tuc: Radial Velocity Variations, Thomas Lebzelter, Peter R. Wood, Kenneth H. Hinkle, Richard R. Joyce, Francis C. Fekel
Long Period Variables In The Globular Cluster 47 Tuc: Radial Velocity Variations, Thomas Lebzelter, Peter R. Wood, Kenneth H. Hinkle, Richard R. Joyce, Francis C. Fekel
Information Systems and Engineering Management Research Publications
We present near infrared velocity curves for 12 long period variables (LPVs) in the globular cluster 47 Tuc (NGC 104). New light curves are also presented for these variables. Results are compared with the period-luminosity sequences occupied by the LPVs in the LMC. Sequence C variables (fundamental mode pulsators) have larger velocity amplitudes than sequence B variables (first overtone pulsators). We show that, at similar luminosities, higher mass loss rates are associated with larger pulsation amplitudes. One variable (V18) does not fit the normal period luminosity sequences and it has an unusually large amount of circumstellar dust, suggesting that it …
The N2k Consortium. I. A Hot Saturn Planet Orbiting Hd 88133, Debra A. Fischer, Gregory Laughlin, Paul Butler, Geoff W. Marcy, John Johnson, Greg Henry, Jeff Valenti, Steve Vogt, Mark Ammons, Sarah Robinson, Greg Spear, Jay Strader, Peter Driscoll, Abby Fuller, Teresa Johnson, Elizabeth Manrao, Chris Mccarthy, Melesio Muñoz, Kok Leong Tah, Jason Wright, Shigeru Ida, Bun'ei Sato, Eri Toyota, Dante Minniti
The N2k Consortium. I. A Hot Saturn Planet Orbiting Hd 88133, Debra A. Fischer, Gregory Laughlin, Paul Butler, Geoff W. Marcy, John Johnson, Greg Henry, Jeff Valenti, Steve Vogt, Mark Ammons, Sarah Robinson, Greg Spear, Jay Strader, Peter Driscoll, Abby Fuller, Teresa Johnson, Elizabeth Manrao, Chris Mccarthy, Melesio Muñoz, Kok Leong Tah, Jason Wright, Shigeru Ida, Bun'ei Sato, Eri Toyota, Dante Minniti
Information Systems and Engineering Management Research Publications
The N2K ("next 2000") consortium is carrying out a distributed observing campaign with the Keck, Magellan, and Subaru telescopes, as well as the automatic photometric telescopes of Fairborn Observatory, in order to search for short-period gas giant planets around metal-rich stars. We have established a reservoir of more than 14,000 main-sequence and subgiant stars closer than 110 pc, brighter than V = 10.5, and with 0.4 < B - V < 1.2. Because the fraction of stars with planets is a sensitive function of stellar metallicity, a broadband photometric calibration has been developed to identify a subset of 2000 stars with [Fe/H] > 0.1 dex for this survey. We outline the strategy and report the detection of a planet orbiting the metal-rich G5 IV star HD 88133 with a period of 3.41 days, semivelocity amplitude K = …
A Study Of Bright Southern Long Period Variables, Thomas Lebzelter, Kenneth H. Hinkle, Peter R. Wood, Richard R. Joyce, Francis C. Fekel
A Study Of Bright Southern Long Period Variables, Thomas Lebzelter, Kenneth H. Hinkle, Peter R. Wood, Richard R. Joyce, Francis C. Fekel
Information Systems and Engineering Management Research Publications
In this paper we present radial velocity curves of AGB variables that exhibit various kinds of anomalies: semiregular variables (SRVs) with typical mira periods, SRVs exceeding the mira 2.5 mag amplitude limit, miras with secondary maxima in their light curves, and a SRV with a long secondary period. The stars with reliable Hipparcos parallaxes from this and from previous studies are plotted in a -diagram. Our objects nicely follow the -relations determined for the LMC. This allows the pulsation mode to be identified. While all miras fall on the fundamental mode sequence, the SRVs fall on both the first overtone …
Hd 166181 = V815 Herculis, A Single-Lined Spectroscopic Multiple System, Francis C. Fekel, David J. Barlow, Colin D. Scarfe, Sylvie Jancart, Dimitri Pourbaix
Hd 166181 = V815 Herculis, A Single-Lined Spectroscopic Multiple System, Francis C. Fekel, David J. Barlow, Colin D. Scarfe, Sylvie Jancart, Dimitri Pourbaix
Information Systems and Engineering Management Research Publications
We have obtained extensive spectroscopic and velocity spectrometer observations of HD 166181, a previously known single-lined spectroscopic binary. Our improved orbit for the G6 V primary has a period of 1.8098343 days and is circular. Although the lines of additional components have not been detected, radial velocity measurements confirm that the system has additional velocity variations with a period of 2092 days, or 5.73 yr. This long-period orbit has an eccentricity of 0.76. An analysis of the Hipparcos observations produces a well-determined astrometric orbit for the long-period system that has an inclination of 78°. Mass estimates of the components in …
Five New Extrasolar Planets, Geoffrey W. Marcy, R. Paul Butler, Steve Vogt, Debra A. Fischer, Gregory W. Henry, Gregory Laughlin, Jason T. Wright, John A. Johnson
Five New Extrasolar Planets, Geoffrey W. Marcy, R. Paul Butler, Steve Vogt, Debra A. Fischer, Gregory W. Henry, Gregory Laughlin, Jason T. Wright, John A. Johnson
Information Systems and Engineering Management Research Publications
We report multiple Doppler measurements of five nearby FGK main-sequence stars and subgiants obtained during the past 4-6 yr at the Keck Observatory. These stars, namely, HD 183263, HD 117207, HD 188015, HD 45350, and HD 99492, all exhibit coherent variations in their Doppler shifts consistent with a planet in Keplerian motion. The five new planets occupy known realms of planetary parameter space, including a wide range of orbital eccentricities, e = 0-0.78, and semimajor axes, 0.1-3.8 AU, that provide further statistical information about the true distributions of various properties of planetary systems. One of the planets, HD 99492b, has …
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
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. …
Spectroscopic Orbits Of Potential Interferometric Binaries, Francis C. Fekel, Jocelyn Tomkin
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)
Managing The Operations Of The Tsu 2-M Automatic Spectroscopic Telescope, Joel A. Eaton, Michael Williamson
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.
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
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.
Photospheric Temperature Measurements In Young Main Sequence Stars, Katia Biazzo, Antonio Frasca, Gregory W. Henry, S. Catalano, Ettore Marilli
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 …
Why Do Some Spotted Stars Become Bluer As They Become Fainter?, Vidar Aarum-Ulvås, Gregory W. Henry
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 …
Chromospherically Active Stars. Xxiii. The Triple System Hd 7205=Qu Andromedae, Francis C. Fekel
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 …
Chromospherically Active Stars. Xxii. Hd 18955, A Massive K Dwarf Binary, Francis C. Fekel, Gregory W. Henry, Frank M. Alston
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 …
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
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 …
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
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. …
Rotational Velocities Of B, A, And Early‐F Narrow‐Lined Stars, Francis C. Fekel
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.
Bv Photometry Of Ux Ari In The Period 1987–2002, Vidar Aarum Ulvås, Gregory W. Henry
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.
The Orbit And Pulsation Periods Of The Γ Doradus Variable Hr 6844 (V2502 Ophiuchi), Francis C. Fekel, Gregory W. Henry
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 …
Spectroscopy Of Early F Stars: Γ Doradus Candidates And Possible Metallic Shell Stars, Francis C. Fekel, Phillip B. Warner, Anthony B. Kaye
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 …