Advantages of Automated Observing with Small Telescopes

Eaton, J. A.; Henry, Gregory W.; Fekel, Francis C.

doi:10.1007/978-94-010-0253-0_38

Cited by 54 publications

(51 citation statements)

References 25 publications

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“…4, 8, and 12, top three panels). We interpret these results in the context of the random-spot model (RSM ) of Eaton et al (1996). The RSM uses large numbers (10-40) of moderately sized dark spots placed randomly on a differentially rotating star to reproduce the light curves of chromospherically active stars.…”

Section: Spot Cyclesmentioning

confidence: 89%

“…If the spots are also allowed to decay and appear at random on the star, with typical lifetimes of several years, then, in addition to further changes in the shape of the light curves, the RSM also predicts the kind of long-term light variations observed in most chromospherically active stars without the necessity of magnetic cycles to drive these changes. Eaton et al (1996) demonstrated that the RSM does an excellent job of producing light curves that strongly resemble the actual light curves of chromospherically active stars on both rotational and decadal timescales. The appearances of the light curves of HD 37824, HD 181809, and HD 217188, as well as the lack of long-term periodic changes in brightness, amplitude, and period in these stars, are also consistent with the RSM.…”

Section: Spot Cyclesmentioning

confidence: 97%

“…Prior to 1992, when a new precision photometer was installed on the telescope, the precision of the observations was approximately 0.012 mag. Further information on the operation of our APTs can be found in Henry (1995aHenry ( , 1995bHenry ( , 1999 and Eaton et al (2003).…”

Section: Photometric Observations and Reductionsmentioning

confidence: 99%

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Chromospherically Active Stars. XXIV. The Giant, Single-lined Binaries HD 37824, HD 181809, and HD 217188

Fekel

Henry

2005

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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 and a moderately high eccentricity of 0.470. The spectral type of the primary is K0 III, while the secondary is likely an M dwarf. All three systems are estimated to have near solar iron abundances. Photometric observations spanning 15-16 years for all three stars yield mean photometric periods of 53.12, 59.85, and 90.89 days for HD 37824, HD 181809, and HD 217188, respectively. Thus, HD 37824 is rotating synchronously with the orbital period, while HD 181809 and HD 217188 are both rotating considerably slower than synchronously. All three stars show longterm variations in mean brightness and photometric amplitude, but no correlations are observed between the seasonal mean brightness, photometric amplitude, and seasonal photometric period in any of the stars. No clear evidence for long-term periodic variations in any of these parameters is present. The circular orbit of HD 37824 and the synchronous rotation of its K giant argue that the star is in the core helium-burning phase of its evolution. The giant components of HD 181809 and HD 217188 are asynchronous rotators, and both systems have eccentric orbits. Thus, those two stars are likely first-ascent giants.

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Section: Spot Cyclesmentioning

confidence: 89%

Section: Spot Cyclesmentioning

confidence: 97%

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Chromospherically Active Stars. XXIV. The Giant, Single-lined Binaries HD 37824, HD 181809, and HD 217188

Fekel

Henry

2005

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“…The automatic telescopes, photometers, observing procedures, and data reduction techniques are described in Henry (1999). Further details on the development and operation of the automated telescopes can be found in Henry (1995aHenry ( , 1995b and Eaton et al (2003).…”

Section: Photometry Of the Host Starsmentioning

confidence: 99%

Five New Multicomponent Planetary Systems

Vogt

Butler

Marcy

et al. 2005

ApJ

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233

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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 È . HD 128311 ( K0 V ) has two planets (one previously known) with minimum masses (M sin i) of 2.18M J and 3.21M J 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 masses and periods of (M sin i b ¼ 1:36M J , P b ¼ 1:08 yr) and (M sin i c ¼ 1:02M J , P c ¼ 4:4 yr). HD 50499 (G1 V ) has a planet with P ¼ 6:8 yr and M sin i ¼ 1:7M J , and the velocity residuals exhibit a trend of À4.8 m s À1 yr À1 , indicating a more distant companion with P > 10 yr and minimum mass of 2M J . HD 37124 (G4 IV-V ) has three planets, one having M sin i ¼ 0:61M J and P ¼ 154:5 days, as previously known. We find two plausible triple-planet models that fit the data, both having a second planet near P ¼ 840 days, with the more likely model having its third planet in a 6 yr orbit and the other one in a 29 day orbit. For HD 190360, we confirm the planet having P ¼ 7:9 yr and M sin i ¼ 1:5M J as found by the Geneva team, but we find a distinctly noncircular orbit with e ¼ 0:36 AE 0:03, rendering this not an analog of Jupiter as had been reported. Our velocities also reveal a second planet with P ¼ 17:1 days and M sin i ¼ 18:1 M È . HD 217107 (G8 IV) has a previously known ''hot Jupiter'' with M sin i ¼ 1:4M J and P ¼ 7:13 days, and we confirm its high eccentricity, e ¼ 0:13. The velocity residuals reveal an outer companion in an eccentric orbit, having minimum mass of M sin i > 2M J , eccentricity e $ 0:5, and a period P > 8 yr, implying a semimajor axis a > 4 AU and providing an opportunity for direct detection. We have obtained high-precision photometry of five of the six planetary host stars with three of the automated telescopes at Fairborn Observatory. We can rule out significant brightness variations in phase with the radial velocities in most cases, thus supporting planetary reflex motion as the cause of the velocity variations. Transits are ruled out to very shallow limits for HD 217107 and are also shown to be unlikely for the prospective inner planets of the HD 37124 and HD 108874 systems. HD 128311 is photometrically variable with an amplitude of 0.03 mag and a period of 11.53 days, which is much shorter than the orbital periods of its two planetary companions. This rotation period explains the origin of periodic velocity residuals to the two-planet model of this star. All of the planetary systems here would be further constrained with astrometry by the Space Interferometry Mission.

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“…Six transits were obtained in [2001][2002][2003][2004] with the T8 and T10 Automatic Photometric Telescopes (APTs) located at Fairborn Observatory in the Patagonia Mountains of southern Arizona ( Henry 1999;Eaton et al 2003). The transits of HD 209458b were codiscovered in 2000 using data from the T8 APT ( Henry et al 2000).…”

Section: Automatic Photometric Telescopementioning

confidence: 99%

System Parameters of the Transiting Extrasolar Planet HD 209458b

Wittenmyer

Welsh

Orosz

et al. 2005

ApJ

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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, 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. Our set of system parameters agrees with previously published results, although with improved accuracy. For example, applying robust limits on the stellar mass of 0.93-1.20 M , we find 1:26R J < R planet < 1:42R J and 0:59M J < M planet < 0:70M J . We can reduce the uncertainty of these estimates by including a stellar mass-radius relation constraint, yielding R planet ¼ 1:35 AE 0:07 ð Þ R J and M planet ¼ 0:66 AE 0:04 ð Þ M J . Our results verify that the planetary radius is 10%-20% larger than predicted by irradiated planet evolution models, confirming the need for an additional mechanism to slow the evolutionary contraction of the planet. A revised ephemeris is derived, T 0 ¼ 2; 452; 854:82545 þ 3:52474554E ( HJD), which now contains an uncertainty in the period of 0.016 s and should facilitate future searches for planetary satellites and other bodies in the HD 209458 system. Subject headingg s: planetary systems -stars: individual ( HD 209458)

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Advantages of Automated Observing with Small Telescopes

Cited by 54 publications

References 25 publications

Chromospherically Active Stars. XXIV. The Giant, Single-lined Binaries HD 37824, HD 181809, and HD 217188

Chromospherically Active Stars. XXIV. The Giant, Single-lined Binaries HD 37824, HD 181809, and HD 217188

Five New Multicomponent Planetary Systems

System Parameters of the Transiting Extrasolar Planet HD 209458b

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