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The Pennsylvania State University The Graduate School Eberly College of Science A SEARCH FOR PLANETS AROUND RED STARS A Dissertation in Astronomy and Astrophysics by Sara Gettel c 2012 Sara Gettel ! Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy December 2012 1 The dissertation of Sara Gettel was reviewed and approved by the following: Alex Wolszczan Evan Pugh Professor of Astronomy and Astrophysics Dissertation Adviser Chair of Committee Lawrence W. Ramsey Distinguished Senior Scholar & Professor of Astronomy and Astrophysics John D. Mathews Professor of Electrical Engineering Mercedes Richards Professor of Astronomy and Astrophysics Kevin Luhman Associate Professor of Astronomy and Astrophysics Jason T. Wright Assistant Professor of Astronomy and Astrophysics Donald P. Schneider Professor of Astronomy and Astrophysics Head of the Department of Astronomy and Astrophysics 1 Signatures on file in the Graduate School. iii Abstract Our knowledge of planets around other stars has expanded drastically in recent years, from a handful Jupiter-mass planets orbiting Sun-like stars, to encompass a wide range of planet masses and stellar host types. In this thesis, I review the development of radial velocity planet searches and present results from projects focusing on the detection of planets around two classes of red stars. The first project is part of the Penn State - Toru´nPlanet Search (PTPS) for substellar companions to K giant stars using the Hobby-Eberly Telescope (HET). The results of this work include the discovery of planetary systems around five evolved stars. These systems illustrate several of the differences between planet detection around giants and Solar-type stars, including increased masses and a lack of short period planets. One planet has a nearly six year orbit, the longest announced to date around a giant star, with an amplitude approaching the limits of detectability due to stellar ‘jitter’. Two more of these systems also show long-term radial velocity trends which are likely caused by the presence of an additional, more distant binary companion. The remaining two systems show increased radial velocity noise, typical of giant systems. Finally I show that, if the stellar jitter is caused by p-mode oscillations, the amplitude of this noise is anti-correlated with metallicity. The second project focuses on the expansion of the current radial velocity calibra- tion methods to a new wavelength regime. The absorption cell technique is modified to use the telluric O2 and water vapor bands found between 6000-9000 A.˚ These features ∼ iv 1 have been found to be stable to 10 m s− and allow access to the increased red flux ∼ of low-mass and evolved stars. I carry out a mock planet search of six early M dwarfs that are known to be radial velocity stable, providing a recoverable null result. Measure- ments are also made of several telluric standards, to improve the characterization of the atmospheric conditions at the time of observation. Radial velocities are measured by forward modeling the observations as a combi- nation of a best-fit model telluric spectrum and a deconvolved stellar template, convolved with a best-fit point-spread function (PSF). These measurements are tested using a small number of blocks and compared to analogous measurements made using the standard iodine calibration. This small sample of blocks is then extrapolated to the full wave- 1 length range, yielding a precision of 20 m s− for the iodine calibration and 30 m ∼ ∼ 1 s− for telluric calibration. These relatively modest precisions may be improved in the future both by improving portions of the PSF modeling and deconvolution algorithms, and by increasing the signal-to-noise ratio (S/N) of the observations. Nevertheless, it is reassuring to obtain relatively similar results with the two calibration methods and even with the present level of precision, telluric calibration would be able to detect a Neptune-mass planet in the habitable zone of an M dwarf. v Table of Contents List of Tables ...................................... vii List of Figures ..................................... viii Preface ......................................... x Acknowledgments ................................... xi Chapter 1. Introduction ................................ 1 1.1 RadialVelocityPlanetDetection . .1 1.1.1 Method .............................. 1 1.1.2 Stellar Contamination . 5 1.1.3 Development ........................... 7 1.1.4 Formation & Characteristics of the Exoplanet Population . 9 1.2 Detecting Planets around Giant Stars . 13 1.2.1 Stellar Evolution . 14 1.2.2 Lack of Hot Jupiters . 16 1.2.3 Metallicity - Planet Frequency Correlation . 18 1.2.4 Stellar Mass - Planet Mass Correlation . 19 1.2.5 Stellar Variability . 20 1.3 Radial Velocity Measurements with Telluric Features . 22 1.3.1 Previous Work . 22 1.3.2 Detecting Planets around Low Mass Stars . 25 1.3.3 Radial Velocity Information Content . 26 1.3.4 Potential Uses of Telluric Calibration . 28 1.4 Outline .................................. 29 Chapter 2. Penn State - Toru´nPlanet Search .................... 42 2.1 Overview ................................. 42 2.2 Observations . 44 2.3 Measuring Stellar Parameters . 45 2.4 Measurements & Modeling of Radial Velocity Variations . 47 2.5 Bisector&PhotometryAnalysis . 49 2.6 ‘Fuzzy’Systems.............................. 50 2.6.1 HD 240237 . 51 2.6.2 HD 96127 . 52 2.6.3 Jitter - Metallicity Correlation . 54 2.7 LongPeriodSystems........................... 56 2.7.1 HD 219415 . 56 2.7.2 Noise Floor . 58 2.8 SystemswithRamps........................... 59 vi 2.8.1 BD+48 738 . 59 2.8.2 BD+20 274 . 61 2.8.3 Binary Companions . 63 2.9 UnresolvedSystems............................ 65 2.9.1 HD 102103 . 65 2.10 HighlightsofthePTPSSurvey . 68 Chapter 3. Observations of Radial Velocity Stable M Dwarfs ........... 100 3.1 Targets . 101 3.2 Data Collection . 101 3.3 Data Reduction . 103 3.4 Wavelength Calibration with ThAr . 106 Chapter 4. Forward Modeling of Radial Velocity Measurements ......... 111 4.1 IodineTechnique ............................. 111 4.1.1 Requirements for Precise Doppler Measurements . 111 4.1.2 Modeling the Observations . 113 4.1.3 Results with Iodine Calibration . 116 4.2 Modification of the Iodine Technique for Telluric Features . 118 4.3 ModelingTelluricSpectra . 119 4.4 GeneratingStellarTemplates . 121 4.5 Testing at 5900 A.............................˚ 122 4.6 Extrapolation to Other Bands . 124 Chapter 5. Summary & Future Prospects ...................... 148 5.1 Summary . 148 5.1.1 Planets around Giant Stars . 148 5.1.2 Measuring Radial Velocities with Telluric Lines . 152 Bibliography ...................................... 155 Appendix. Permissions ................................ 167 vii List of Tables 1.1 GiantStarswithPlanets. 37 2.1 StellarParameters .............................. 69 2.2 OrbitalParameters.............................. 70 2.3 Possible Orbital Solutions for HD 102103 . 70 2.4 Planet-Hosting Giants with Published RMS Values . 71 2.5 Relative Radial Velocity Measurements of HD 240237 . 72 2.6 Relative Radial Velocity Measurements of HD 96127 . 73 2.7 Relative Radial Velocity Measurements of HD 219415 . 74 2.8 Relative Radial Velocity Measurements of BD+48 738 . 75 2.9 Relative Radial Velocity Measurements of BD+20 274 . 76 2.10 Relative Radial Velocity Measurements of HD 102103 . 78 3.1 Radial Velocity Stable Targets . 108 4.1 PhotonLimitedVelocityPrecision . 143 viii List of Figures 1.1 RadialVelocityDiscoverySpace . 30 1.2 Starspot Contamination . 31 1.3 LineBisectorVariations . 32 1.4 Lack of Hot Jupiters around Giant Stars . 33 1.5 MetallicityDependenceofDwarfs&Giants . 34 1.6 MetallicityDependenceofGiants . 35 1.7 StellarMass-PlanetMassDependence . 36 1.8 R-band Atmospheric Transmission . 38 1.9 K&MDwarfFlux.............................. 39 1.10 Reflex Amplitude in the Habitable Zone . 40 1.11GiantStarFlux................................ 41 2.1 HR Diagram of PTPS Targets . 81 2.2 Radial Velocity Measurements of HD 240237 . 82 2.3 Bisector & Photometry Measurements of HD 240237 . 83 2.4 Radial Velocity Measurements of HD 96127 . 84 2.5 Bisector & Photometry Measurements of HD 96127 . 85 2.6 StellarJitterv.Metallicity . 86 2.7 Radial Velocity Measurements of HD 219415 . 87 2.8 Bisector & Photometry Measurements of HD 219415 . 88 2.9 GiantStarDiscoverySpace . 89 2.10 Radial Velocity Measurements of BD+48 738 . 90 2 2.11 χ grid of BD+48 738 . 91 2.12 Bisector & Photometry Measurements of BD+48 738 . 92 2.13 Radial Velocity Measurements of BD+20 274 . 93 2.14 Bisector & Photometry Measurements of BD+20 274 . 94 2.15 Radial Velocity Measurements of HD 102103 . 95 2.16 Radial Velocity Measurements of HD 102103 . 96 2.17 Bisector & Photometry Measurements of HD 102103 . 97 2.18 Bisector & Photometry Measurements of HD 102103 . 98 2 2.19 χ grid of HD 102103 . 99 3.1 Sample Target and Telluric Standard Spectra . 108 3.2 Cross-DisperserRepeatability . 109 3.3 Cross-Disperser Repeatability with Consecutive Measurements . 110 4.1 SampleIodineBlock ............................. 128 4.2 Iodine Radial Velocities of GJ 184 . 129 4.3 Iodine Radial Velocities of GJ 272 . 130 4.4 Iodine Radial Velocities of GJ 277.1 . 131 4.5 Iodine Radial Velocities of GJ 281 . 132 4.6 Iodine Radial Velocities of GJ 328 . 133 ix 4.7 Iodine Radial Velocities of GJ 353 . 134 4.8 SampleTelluricBlock ............................ 135 4.9 TelluricModelingwithTERRASPEC . 136 4.10 Radial Velocities Measured with Telluric Features
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  • Gliese 49: Activity Evolution and Detection of a Super-Earth? a HADES and CARMENES Collaboration

    Gliese 49: Activity Evolution and Detection of a Super-Earth? a HADES and CARMENES Collaboration

    Astronomy & Astrophysics manuscript no. Gl49b ©ESO 2020 December 4, 2020 Gliese 49: Activity evolution and detection of a super-Earth? A HADES and CARMENES collaboration M. Perger1; 2, G. Scandariato3, I. Ribas1; 2, J. C. Morales1; 2, L. Affer4, M. Azzaro5, P. J. Amado6, G. Anglada-Escudé6; 7, D. Baroch1; 2, D. Barrado8, F. F. Bauer6, V. J. S. Béjar9; 10, J. A. Caballero8, M. Cortés-Contreras8, M. Damasso11, S. Dreizler12, L. González-Cuesta9; 10, J. I. González Hernández9; 10, E. W. Guenther13, T. Henning14, E. Herrero1; 2, S.V. Jeffers12, A. Kaminski15, M. Kürster14, M. Lafarga1; 2, G. Leto3, M. J. López-González6, J. Maldonado4, G. Micela4, D. Montes16, M. Pinamonti11, A. Quirrenbach15, R. Rebolo9; 10; 17, A. Reiners12, E. Rodríguez6, C. Rodríguez-López6, J. H. M. M. Schmitt18, A. Sozzetti11, A. Suárez Mascareño9; 19, B. Toledo-Padrón9; 10, R. Zanmar Sánchez3, M. R. Zapatero Osorio20, and M. Zechmeister12 (Affiliations can be found after the references) Accepted: 11 March 2019 ABSTRACT Context. Small planets around low-mass stars often show orbital periods in a range that corresponds to the temperate zones of their host stars which are therefore of prime interest for planet searches. Surface phenomena such as spots and faculae create periodic signals in radial velocities and in observational activity tracers in the same range, so they can mimic or hide true planetary signals. Aims. We aim to detect Doppler signals corresponding to planetary companions, determine their most probable orbital configurations, and understand the stellar activity and its impact on different datasets. Methods. We analyzed 22 years of data of the M1.5 V-type star Gl 49 (BD+61 195) including HARPS-N and CARMENES spec- trographs, complemented by APT2 and SNO photometry.