A high-precision radial-velocity survey for other planetary systems

Cochran, William D.; Hatzes, A. P.

doi:10.1007/bf00984532

Cited by 40 publications

(26 citation statements)

References 9 publications

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“…The v sin i and macroturbulent velocity were taken as 8.4 and 12.8 km s~1, respectively. Radial velocities were computed from the synthetic proÐles by Ðrst combining them with an observed iodine spectrum and then processing them with the RV analysis software used in the McDonald Observatory planet search program (Cochran & Hatzes 1996).…”

Section: Cool Spotsmentioning

confidence: 99%

“…However, it seems that the announcement that Polaris was leaving the instability strip was premature for Kamper & Fernie (1998, hereafter KF98) recently reported that due to a miscommunication during the preparation of the earlier paper, the published amplitude was actually a semiamplitude and that the peak-to-peak radial velocity RV amplitude should be about 1.6 km s~1, or comparable to the value measured by Dinshaw et al If the decay in the amplitude had indeed been as rapid as was proposed by D89, then the pulsational amplitude would have quickly become undetectable by traditional RV measurements, which have a precision of order 1 km s~1. At McDonald Observatory we have been using precise stellar radial velocity measurements to search for extra solar planets (Cochran & Hatzes 1996) as well as to study lowamplitude pulsations in K giants (e.g., Hatzes & Cochran 1993). The precision of these measurements (p D 10È20 m s~1) was sufficient to enable us to measure the pulsational amplitude of Polaris well below 1 km s~1.…”

Section: Introductionmentioning

confidence: 99%

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The Radial Velocity and Spectral Line Bisector Variability of Polaris

Hatzes

Cochran

2000

The Astronomical Journal

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We present precise stellar radial velocity measurements for the Cepheid-type star Polaris taken in 1992È1993. The peak-to-peak amplitude of the pulsations was 1.555^0.056 km s~1 in epoch 1992.4 and 1.517^0.047 km s~1 in epoch 1993.2. These amplitudes are comparable to the one measured by Dinshaw et al. in 1987.75 and Mg I j5528 lines also show variations with the 40 day period, strongly indicating that this period is indeed real. The presence of line bisector variations excludes a low-mass companion object as a cause of the residual radial velocity variations. Two models are considered for the residual radial velocity and bisector span variations : starspots and nonradial pulsations. Although both can reproduce the amplitude and shape of the residual radial velocity variations, the spot models considered were unable to reproduce the overall shape and amplitude of the bisector span variations. The best-Ðt spot model was provided by a single spot with a temperature 500 K cooler than the photosphere with a macroturbulent velocity of zero in the spot. If surface features do exist on Polaris and are responsible for the residual radial variations for this star, then possibly they have a temperature structure and distribution more complicated than the simple models considered here. The best Ðt to all the observed variations was provided by a nonradial m \ 4 mode, although these were not entirely satisfactory having a phase shift of about 0.25 between the observed and predicted bisector variations. Possible explanations for this shift include temperature e †ects, a source function originating in a dynamic stellar atmosphere, or a di †erent pulsation mode than the one that was considered. Although the exact pulsational mode is yet to be identiÐed, we believe that the residual radial velocity variations are due to a long-period pulsation mode. Supporting evidence comes from the fact that three di †erent residual variations with periods near 40 days have now been seen in Polaris and it is unlikely that these variations are due to rotational modulation by surface features on a star that is di †erentially rotating.

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Section: Cool Spotsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Radial Velocity and Spectral Line Bisector Variability of Polaris

Hatzes

Cochran

2000

The Astronomical Journal

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“…A list of the most productive ones includes the Geneva Southern Planet Search Programme, carried out with the CORALIE spectrograph mounted on the 1.2-m Euler swiss telescope Udry et al 2000a) at ESO-La Silla observatory, the California & Carnegie Planet Search with the HAMILTON spectrograph at the Lick Observatory (Marcy & Butler 1992) and the HIRES spectrograph mounted on the 10-m Keck-1 telescope (Vogt et al 1994) at the W. M. Keck Observatory, the G-Dwarf Planet Search also performed with the HIRES spectrograph at Keck Observatory , the Anglo-Australian Planet Search with the UCLES echelle spectrograph mounted on the 3.92-m Anglo-Australian Telescope (Tinney et al 2001), the AFOE Planet Search (Korzennik et al 1998) using the AFOE spectrograph mounted on the 1.5-m telescope at the Whipple Observatory and the McDonald Planetary Search (Cochran & Hatzes 1994) using the McDonald Observatory 2.7-m telescope coude spectrograph.…”

Section: Introductionmentioning

confidence: 99%

The ELODIE survey for northern extra-solar planets

Perrier

Sivan

Naef

et al. 2003

A&A

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Abstract. Precise radial-velocity observations at Haute-Provence Observatory (OHP, France) with the ELODIE echelle spectrograph have been undertaken since 1994. In addition to several discoveries described elsewhere, including and following that of 51 Peg b, they reveal new sub-stellar companions with essentially moderate to long periods. We report here about such companions orbiting five solar-type stars (HD 8574, HD 23596, HD 33636, HD 50554, HD 106252) and one sub-giant star (HD 190228). The companion of HD 8574 has an intermediate period of 227.55 days and a semi-major axis of 0.77 AU. All other companions have long periods, exceeding 3 years, and consequently their semi-major axes are around or above 2 AU. The detected companions have minimum masses m 2 sin i ranging from slightly more than 2 M Jup to 10.6 M Jup . These additional objects reinforce the conclusion that most planetary companions have masses lower than 5 M Jup but with a tail of the mass distribution going up above 15 M Jup . The orbits are all eccentric and 4 out of 6 have an eccentricity of the order of 0.5. Four stars exhibit solar metallicity, one is metal-rich and one metal-poor. With 6 new extra-solar planet candidates discovered, increasing their total known to-date number to 115, the ELODIE Planet Search Survey yield is currently 18. We emphasize that 3 out of the 6 companions could in principle be resolved by diffraction-limited imaging on 8 m-class telescopes depending on the achievable contrast, and therefore be primary targets for first attempts of extra-solar planet direct imaging.

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“…Campbell et al 1988, Walker et al 1994. The remaining three have been ongoing for seven years and have involved 20 stars , 13 stars (McMillan et al 1994), and 30 stars (Cochran & Hatzes 1994). The searches by Duquennoy & Mayor led to nine cases where the inferred wipsini value was <0.08Af o ; that is, possible cases of brown dwarf companions.…”

Section: Search Results Since 1980mentioning

confidence: 99%

Completing the Copernican Revolution: The Search for Other Planetary Systems

Black¹

1995

Annual Review of Astronomy and Astrophysics

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The past few decades have witnessed significant advances in our understanding of how stars form, and there has been an associated increase in our knowledge of conditions and phenomena in the early solar system. These have led to the formulation of a paradigm for the origin of the solar system that is sufficiently complete that its basic elements can be tested directly through observations. A simple, but profound, consequence of the paradigm is that most if not all stars should be accompanied by planetary systems. The accuracy of instruments that can be used in such searches has improved to the point that Jupiter-like companions to a number of nearby stars could be detected. However, the results to date are that no other planetary systems have been detected, and the absence of detection is becoming statistically significant, particularly as it relates to the existence of brown dwarf companions to main-sequence stars.

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A high-precision radial-velocity survey for other planetary systems

Cited by 40 publications

References 9 publications

The Radial Velocity and Spectral Line Bisector Variability of Polaris

The Radial Velocity and Spectral Line Bisector Variability of Polaris

The ELODIE survey for northern extra-solar planets

Completing the Copernican Revolution: The Search for Other Planetary Systems

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