[en] I present chromospheric-activity measurements of ∼670 F, G, K, and M main-sequence stars in the Southern Hemisphere, from ∼8000 archival high-resolution echelle spectra taken at Las Campanas Observatory since 2004. These stars were targets from the Old Magellan Planet Search, and are now potential targets for the New Magellan Planet Search that will look for rocky and habitable planets. Activity indices (S values) are derived from Ca II H and K line cores and then converted to the Mount Wilson system. From these measurements, chromospheric (log R'_HK) indices are derived, which are then used as indicators of the level of radial-velocity jitter, age, and rotation periods these stars present.

[en] We present a new precision radial velocity (RV) data set that reveals multiple planets orbiting the stars in the ∼360 au, G2+G2 “twin” binary HD 133131AB. Our six years of high-resolution echelle observations from MIKE and five years from the Planet Finder Spectrograph (PFS) on the Magellan telescopes indicate the presence of two eccentric planets around HD 133131A with minimum masses of 1.43 ± 0.03 and 0.63 ± 0.15 ${\mathcal{M}}_{\mathrm{J}}$ at 1.44 ± 0.005 and 4.79 ± 0.92 au, respectively. Additional PFS observations of HD 133131B spanning five years indicate the presence of one eccentric planet of minimum mass 2.50 ± 0.05 ${\mathcal{M}}_{\mathrm{J}}$ at 6.40 ± 0.59 au, making it one of the longest-period planets detected with RV to date. These planets are the first to be reported primarily based on data taken with the PFS on Magellan, demonstrating the instrument’s precision and the advantage of long-baseline RV observations. We perform a differential analysis between the Sun and each star, and between the stars themselves, to derive stellar parameters and measure a suite of 21 abundances across a wide range of condensation temperatures. The host stars are old (likely ∼9.5 Gyr) and metal-poor ([Fe/H] ∼ −0.30), and we detect a ∼0.03 dex depletion in refractory elements in HD 133131A versus B (with standard errors ∼0.017). This detection and analysis adds to a small but growing sample of binary “twin” exoplanet host stars with precise abundances measured, and represents the most metal-poor and likely oldest in that sample. Overall, the planets around HD 133131A and B fall in an unexpected regime in planet mass–host star metallicity space and will serve as an important benchmark for the study of long-period giant planets.

[en] Five new planets orbiting G and K dwarfs have emerged from the Magellan velocity survey. These companions are Jovian-mass planets in eccentric (e ≥ 0.24) intermediate- and long-period orbits. HD 86226b orbits a solar metallicity G2 dwarf. The M_P sin i mass of the planet is 1.5 M_JUP, the semimajor axis is 2.6 AU, and the eccentricity is 0.73. HD 129445b orbits a metal-rich G6 dwarf. The minimum mass of the planet is M_P sin i = 1.6 M_JUP, the semimajor axis is 2.9 AU, and the eccentricity is 0.70. HD 164604b orbits a K2 dwarf. The M_P sin i mass is 2.7 M_JUP, the semimajor axis is 1.3 AU, and the eccentricity is 0.24. HD 175167b orbits a metal-rich G5 star. The M_P sin i mass is 7.8 M_JUP, the semimajor axis is 2.4 AU, and the eccentricity is 0.54. HD 152079b orbits a G6 dwarf. The M_P sin i mass of the planet is 3 M_JUP, the semimajor axis is 3.2 AU, and the eccentricity is 0.60.

[en] We report low-mass companions orbiting five solar-type stars that have emerged from the Magellan precision Doppler velocity survey, with minimum (Msin i) masses ranging from 1.2 to 25 M _JUP. These nearby target stars range from mildly metal-poor to metal-rich, and appear to have low chromospheric activity. The companions to the brightest two of these stars have previously been reported from the CORALIE survey. Four of these companions (HD 48265-b, HD 143361-b, HD 28185-b, and HD 111232-b) are low-mass Jupiter-like planets in eccentric intermediate- and long-period orbits. On the other hand, the companion to HD 43848 appears to be a long-period brown dwarf in a very eccentric orbit.

[en] We present new, high-precision Doppler radial velocity (RV) data sets for the nearby K3V star HD 219134. The data include 175 velocities obtained with the HIRES Spectrograph at the Keck I Telescope and 101 velocities obtained with the Levy Spectrograph at the Automated Planet Finder Telescope at Lick Observatory. Our observations reveal six new planetary candidates, with orbital periods of P = 3.1, 6.8, 22.8, 46.7, 94.2, and 2247 days, spanning masses of $\mathcal{M}\mathrm{s}\mathrm{i}\mathrm{n}i=3.8,$ 3.5, 8.9, 21.3, 10.8, and $108{\mathcal{M}}_{\oplus <!--\; ???\; -->}$, respectively. Our analysis indicates that the outermost signal is unlikely to be an artifact induced by stellar activity. In addition, several years of precision photometry with the T10 0.8 m automatic photometric telescope at Fairborn Observatory demonstrated a lack of brightness variability to a limit of ∼0.0002 mag, providing strong support for planetary-reflex motion as the source of the RV variations. The HD 219134 system with its bright (V = 5.6) primary provides an excellent opportunity to obtain detailed orbital characterization (and potentially follow-up observations) of a planetary system that resembles many of the multiple-planet systems detected by Kepler, which are expected to be detected by NASA’s forthcoming TESS Mission and by ESA’s forthcoming PLATO Mission.

[en] We report two low-mass companions orbiting the nearby K7 dwarf GJ 221 that have emerged from reanalyzing 4.4 yr of publicly available HARPS spectra complemented with 2 years of high-precision Doppler measurements with Magellan/PFS. The HARPS measurements alone contain the clear signal of a low-mass companion with a period of 125 days and a minimum mass of 53.2 M_⊕ (GJ 221b), falling in a mass range where very few planet candidates have been found (sub-Saturn desert). The addition of 17 PFS observations allows the confident detection of a second low-mass companion (6.5 M_⊕) in a hot orbit (3.87 day period, GJ 221c). Spectroscopic and photometric calibrations suggest that GJ 221 is slightly depleted ([Fe/H] ∼ –0.1) compared to the Sun, so the presence of two low-mass companions in the system confirms the trend that slightly reduced stellar metallicity does not prevent the formation of planets in the super-Earth to sub-Saturn mass regime.

[en] We present precise Doppler observations of WASP-47, a transiting planetary system featuring a hot Jupiter with both inner and outer planetary companions. This system has an unusual architecture and also provides a rare opportunity to measure planet masses in two different ways: the Doppler method, and the analysis of transit-timing variations (TTV). Based on the new Doppler data, obtained with the Planet Finder Spectrograph on the Magellan/Clay 6.5 m telescope, the mass of the hot Jupiter is $370\pm <!--\; ??\; -->29M_{\oplus <!--\; ???\; -->}.$ This is consistent with the previous Doppler determination as well as the TTV determination. For the inner planet WASP-47e, the Doppler data lead to a mass of $12.2\pm <!--\; ??\; -->3.7M_{\oplus <!--\; ???\; -->},$ in agreement with the TTV-based upper limit of <22 M_⊕ (95% confidence). For the outer planet WASP-47d, the Doppler mass constraint of $10.4\pm <!--\; ??\; -->8.4M_{\oplus <!--\; ???\; -->}$ is consistent with the TTV-based measurement of ${15.2}_{-<!--\; ???\; -->7.6}^{+6.7}{M}_{\oplus <!--\; ???\; -->}.$

[en] We provide evidence that the obliquities of stars with close-in giant planets were initially nearly random, and that the low obliquities that are often observed are a consequence of star-planet tidal interactions. The evidence is based on 14 new measurements of the Rossiter-McLaughlin effect (for the systems HAT-P-6, HAT-P-7, HAT-P-16, HAT-P-24, HAT-P-32, HAT-P-34, WASP-12, WASP-16, WASP-18, WASP-19, WASP-26, WASP-31, Gl 436, and Kepler-8), as well as a critical review of previous observations. The low-obliquity (well-aligned) systems are those for which the expected tidal timescale is short, and likewise the high-obliquity (misaligned and retrograde) systems are those for which the expected timescale is long. At face value, this finding indicates that the origin of hot Jupiters involves dynamical interactions like planet-planet interactions or the Kozai effect that tilt their orbits rather than inspiraling due to interaction with a protoplanetary disk. We discuss the status of this hypothesis and the observations that are needed for a more definitive conclusion.

[en] We present high-contrast Magellan adaptive optics images of HD 7449, a Sun-like star with one planet and a long-term radial velocity (RV) trend. We unambiguously detect the source of the long-term trend from 0.6–2.15 μm at a separation of ∼0.″54. We use the object’s colors and spectral energy distribution to show that it is most likely an M4–M5 dwarf (mass ∼0.1–0.2 $M_{\odot <!--\; ???\; -->}$) at the same distance as the primary and is therefore likely bound. We also present new RVs measured with the Magellan/MIKE and Planet Finder Spectrograph spectrometers and compile these with archival data from CORALIE and HARPS. We use a new Markov chain Monte Carlo procedure to constrain both the mass ($><!--\; >\; -->0.17$ $M_{\odot <!--\; ???\; -->}$ at 99% confidence) and semimajor axis (∼18 AU) of the M dwarf companion (HD 7449B). We also refine the parameters of the known massive planet (HD 7449Ab), finding that its minimum mass is ${1.09}_{-<!--\; ???\; -->0.19}^{+0.52}$ M_J, its semimajor axis is ${2.33}_{-<!--\; ???\; -->0.02}^{+0.01}$ AU, and its eccentricity is ${0.8}_{-<!--\; ???\; -->0.06}^{+0.08}$. We use N-body simulations to constrain the eccentricity of HD 7449B to ≲0.5. The M dwarf may be inducing Kozai oscillations on the planet, explaining its high eccentricity. If this is the case and its orbit was initially circular, the mass of the planet would need to be ≲1.5 M_J. This demonstrates that strong constraints on known planets can be made using direct observations of otherwise undetectable long-period companions.

[en] We re-analyze 4 years of HARPS spectra of the nearby M1.5 dwarf GJ 667C available through the European Southern Observatory public archive. The new radial velocity (RV) measurements were obtained using a new data analysis technique that derives the Doppler measurement and other instrumental effects using a least-squares approach. Combining these new 143 measurements with 41 additional RVs from the Magellan/Planet Finder Spectrograph and Keck/High Resolution Echelle Spectrometer spectrometers reveals three additional signals beyond the previously reported 7.2 day candidate, with periods of 28 days, 75 days, and a secular trend consistent with the presence of a gas giant (period ∼10 years). The 28 day signal implies a planet candidate with a minimum mass of 4.5 M_⊕ orbiting well within the canonical definition of the star's liquid water habitable zone (HZ), that is, the region around the star at which an Earth-like planet could sustain liquid water on its surface. Still, the ultimate water supporting capability of this candidate depends on properties that are unknown such as its albedo, atmospheric composition, and interior dynamics. The 75 day signal is less certain, being significantly affected by aliasing interactions among a potential 91 day signal, and the likely rotation period of the star at 105 days detected in two activity indices. GJ 667C is the common proper motion companion to the GJ 667AB binary, which is metal-poor compared to the Sun. The presence of a super-Earth in the HZ of a metal-poor M dwarf in a triple star system supports the evidence that such worlds should be ubiquitous in the Galaxy.