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We review the possible formation and orbital stability of Earth-mass or super Earth-mass planets around either of the stars Alpha Centauri A or B and describe a program at Mt John University Observatory using the Doppler method that aims to detect such planets. From New Zealand, we are able to observe the Alpha Centauri system year-round. This is critical in order to acquire data of sufficient quantity and phase coverage to detect the orbit of a terrestrial-mass planet in the habitable zone. Our observations are being made at high resolution (R = 70,000) and high signal-to-noise with the Hercules vacuum echelle spectrograph attached to the 1-m McLellan telescope by a 25-m long optical fibre and using an iodine cell. We discuss the velocity precision and instrumental stability required for success and outline the progress of the observations so far. At present we are collecting about 10,000 observations of each star, A and B, per year with a typical precision of 2.5 m/s per observation.

The MINiature Exoplanet Radial Velocity Array (MINERVA) is a dedicated observatory of four 0.7 m robotic telescopes fiber-fed to a KiwiSpec spectrograph. The MINERVA mission is to discover super-Earths in the habitable zones of nearby stars. This can be accomplished with MINERVA's unique combination of high precision and high cadence over long time periods. In this work, we detail changes to the MINERVA facility that have occurred since our previous paper. We then describe MINERVA's robotic control software, the process by which we perform 1D spectral extraction, and our forward modeling Doppler pipeline. In the process of improving our forward modeling procedure, we found that our spectrograph's intrinsic instrumental profile is stable for at least nine months. Because of that, we characterized our instrumental profile with a time-independent, cubic spline function based on the profile in the cross dispersion direction, with which we achieved a radial velocity precision similar to using a conventional \"sum-of-Gaussians\" instrumental profile: 1.8 m s−1 over 1.5 months on the RV standard star HD 122064. Therefore, we conclude that the instrumental profile need not be perfectly accurate as long as it is stable. In addition, we observed 51 Peg and our results are consistent with the literature, confirming our spectrograph and Doppler pipeline are producing accurate and precise radial velocities.

The ‘holy grail’ in planet hunting is the detection of an Earth-analogue: a planet with similar mass as the Earth and an orbit inside the habitable zone. If we can find such an Earth-analogue around one of the stars in the immediate solar neighbourhood, we could potentially even study it in such great detail to address the question of its potential habitability. Several groups have focused their planet detection efforts on the nearest stars. Our team is currently performing an intensive observing campaign on the α Centauri system using the High Efficiency and Resolution Canterbury University Large Échelle Spectrograph (Hercules) at the 1 m McLellan telescope at Mt John University Observatory in New Zealand. The goal of our project is to obtain such a large number of radial velocity (RV) measurements with sufficiently high temporal sampling to become sensitive to signals of Earth-mass planets in the habitable zones of the two stars in this binary system. Over the past few years, we have collected more than 45 000 spectra for both stars combined. These data are currently processed by an advanced version of our RV reduction pipeline, which eliminates the effect of spectral cross-contamination. Here we present simulations of the expected detection sensitivity to low-mass planets in the habitable zone by the Hercules programme for various noise levels. We also discuss our expected sensitivity to the purported Earth-mass planet in a 3.24-day orbit announced by Dumusque et al. (2012).

The MINiature Exoplanet Radial Velocity Array (MINERVA) is a dedicated observatory of four 0.7 m robotic telescopes fiber-fed to a KiwiSpec spectrograph. The MINERVA mission is to discover super-Earths in the habitable zones of nearby stars. This can be accomplished with MINERVA’s unique combination of high precision and high cadence over long time periods. In this work, we detail changes to the MINERVA facility that have occurred since our previous paper. We then describe MINERVA’s robotic control software, the process by which we perform 1D spectral extraction, and our forward modeling Doppler pipeline. In the process of improving our forward modeling procedure, we found that our spectrograph’s intrinsic instrumental profile is stable for at least nine months. Because of that, we characterized our instrumental profile with a time-independent, cubic spline function based on the profile in the cross dispersion direction, with which we achieved a radial velocity precision similar to using a conventional “sum-of-Gaussians” instrumental profile: 1.8 m s−1 over 1.5 months on the RV standard star HD 122064. Therefore, we conclude that the instrumental profile need not be perfectly accurate as long as it is stable. In addition, we observed 51 Peg and our results are consistent with the literature, confirming our spectrograph and Doppler pipeline are producing accurate and precise radial velocities.

Abstract The 'holy grail' in planet hunting is the detection of an Earth-analogue: a planet with similar mass as the Earth and an orbit inside the habitable zone. If we can find such an Earth-analogue around one of the stars in the immediate solar neighbourhood, we could potentially even study it in such great detail to address the question of its potential habitability. Several groups have focused their planet detection efforts on the nearest stars. Our team is currently performing an intensive observing campaign on the [alpha] Centauri system using the High Efficiency and Resolution Canterbury University Large Échelle Spectrograph (Hercules) at the 1 m McLellan telescope at Mt John University Observatory in New Zealand. The goal of our project is to obtain such a large number of radial velocity (RV) measurements with sufficiently high temporal sampling to become sensitive to signals of Earth-mass planets in the habitable zones of the two stars in this binary system. Over the past few years, we have collected more than 45 000 spectra for both stars combined. These data are currently processed by an advanced version of our RV reduction pipeline, which eliminates the effect of spectral cross-contamination. Here we present simulations of the expected detection sensitivity to low-mass planets in the habitable zone by the Hercules programme for various noise levels. We also discuss our expected sensitivity to the purported Earth-mass planet in a 3.24-day orbit announced by Dumusque et al. (2012).

The MINiature Exoplanet Radial Velocity Array (MINERVA) is a dedicated observatory of four 0.7m robotic telescopes fiber-fed to a KiwiSpec spectrograph. The MINERVA mission is to discover super-Earths in the habitable zones of nearby stars. This can be accomplished with MINERVA's unique combination of high precision and high cadence over long time periods. In this work, we detail changes to the MINERVA facility that have occurred since our previous paper. We then describe MINERVA's robotic control software, the process by which we perform 1D spectral extraction, and our forward modeling Doppler pipeline. In the process of improving our forward modeling procedure, we found that our spectrograph's intrinsic instrumental profile is stable for at least nine months. Because of that, we characterized our instrumental profile with a time-independent, cubic spline function based on the profile in the cross dispersion direction, with which we achieved a radial velocity precision similar to using a conventional \"sum-of-Gaussians\" instrumental profile: 1.8 m s\\(^{-1}\\) over 1.5 months on the RV standard star HD 122064. Therefore, we conclude that the instrumental profile need not be perfectly accurate as long as it is stable. In addition, we observed 51 Peg and our results are consistent with the literature, confirming our spectrograph and Doppler pipeline are producing accurate and precise radial velocities.

The MINiature Exoplanet Radial Velocity Array (MINERVA) is a US-based observational facility dedicated to the discovery and characterization of exoplanets around a nearby sample of bright stars. MINERVA employs a robotic array of four 0.7 m telescopes outfitted for both high-resolution spectroscopy and photometry, and is designed for completely autonomous operation. The primary science program is a dedicated radial velocity survey and the secondary science objective is to obtain high precision transit light curves. The modular design of the facility and the flexibility of our hardware allows for both science programs to be pursued simultaneously, while the robotic control software provides a robust and efficient means to carry out nightly observations. In this article, we describe the design of MINERVA including major hardware components, software, and science goals. The telescopes and photometry cameras are characterized at our test facility on the Caltech campus in Pasadena, CA, and their on-sky performance is validated. New observations from our test facility demonstrate sub-mmag photometric precision of one of our radial velocity survey targets, and we present new transit observations and fits of WASP-52b -- a known hot-Jupiter with an inflated radius and misaligned orbit. The facility is now in the process of being relocated to its final destination at the Fred Lawrence Whipple Observatory in southern Arizona, and science operations will begin in 2015.

We present a mass determination for the transiting super-Earth rho 1 Cancri e based on nearly 700 precise radial velocity (RV) measurements. This extensive RV data set consists of data collected by the McDonald Observatory planet search and published data from Lick and Keck observatories (Fischer et al. 2008). We obtained 212 RV measurements with the Tull Coude Spectrograph at the Harlan J. Smith 2.7 m Telescope and combined them with a new Doppler reduction of the 131 spectra that we have taken in 2003-2004 with the High-Resolution-Spectrograph (HRS) at the Hobby-Eberly Telescope (HET) for the original discovery of rho 1 Cancri e. Using this large data set we obtain a 5-planet Keplerian orbital solution for the system and measure an RV semi-amplitude of K = 6.29 +/- 0.21 m/s for rho 1 Cnc e and determine a mass of 8.37 +/- 0.38 M_Earth. The uncertainty in mass is thus less than 5%. This planet was previously found to transit its parent star (Winn et al. 2011, Demory et al. 2011), which allowed them to estimate its radius. Combined with the latest radius estimate from Gillon et al. (2012), we obtain a mean density of rho = 4.50 +/- 0.20 g/cm^3. The location of rho 1 Cnc e in the mass-radius diagram suggests that the planet contains a significant amount of volitales, possibly a water-rich envelope surrounding a rocky core.

We present 8 years of high-precision radial velocity (RV) data for HD 204313 from the 2.7 m Harlan J. Smith Telescope at McDonald Observatory. The star is known to have a giant planet (M sin i = 3.5 M_J) on a ~1900-day orbit, and a Neptune-mass planet at 0.2 AU. Using our own data in combination with the published CORALIE RVs of Segransan et al. (2010), we discover an outer Jovian (M sin i = 1.6 M_J) planet with P ~ 2800 days. Our orbital fit suggests the planets are in a 3:2 mean motion resonance, which would potentially affect their stability. We perform a detailed stability analysis, and verify the planets must be in resonance.

We present high-precision radial velocity (RV) observations of four solar-type (F7-G5) stars - HD 79498, HD 155358, HD 197037, and HD 220773 - taken as part of the McDonald Observatory Planet Search Program. For each of these stars, we see evidence of Keplerian motion caused by the presence of one or more gas giant planets in long-period orbits. We derive orbital parameters for each system, and note the properties (composition, activity, etc.) of the host stars. While we have previously announced the two-gas-giant HD 155358 system, we now report a shorter period for planet c. This new period is consistent with the planets being trapped in mutual 2:1 mean-motion resonance. We therefore perform an in-depth stability analysis, placing additional constraints on the orbital parameters of the planets. These results demonstrate the excellent long-term RV stability of the spectrometers on both the Harlan J. Smith 2.7 m telescope and the Hobby-Eberly telescope.