UNIVERSIDAD DE CHILE FACULTAD DE CIENCIAS F´ISICAS Y MATEMATICAS´ DEPARTAMENTO DE ASTRONOM´IA SAFARI: BRIDGING THE GAP BETWEEN RADIAL VELOCITY AND DIRECT IMAGING TESIS PARA OPTAR AL GRADO DE DOCTOR EN CIENCIAS, MENCION´ ASTRONOM´IA BLAKE M PANTOJA PROFESOR GU´IA: JAMES JENKINS MIEMBROS DE LA COMISION:´ JULIEN GIRARD PAULINA LIRA TEILLERY PATRICIO ROJO RUBKE Este trabajo ha sido parcialmente financiado por la beca de doctorado nacional de CONICYT No. 21161783 del a~no2016 SANTIAGO DE CHILE 2019 RESUMEN DE LA MEMORIA PARA OPTAR AL T´ITULO DE DOCTOR EN CIENCIAS, MENCION´ ASTRONOM´IA POR: BLAKE M PANTOJA FECHA: 2019 PROF. GU´IA: JAMES JENKINS SAFARI: BRIDGING THE GAP BETWEEN RADIAL VELOCITY AND DIRECT IMAGING SAFARI: DISMINUYENDO LA BRECHA ENTRE VELOCIDADES RADIALES E IMAGENES´ DIRECTAS El m´etodo de velocidades radiales ha sido muy productivo en la b´usquedade exoplanetas, comen- zando con el descubrimiento de 51 Peg b en 1995 hasta los aproximadamente 800 planetas detec- tados por este m´etodo al d´ıade hoy. Aunque este m´etodo ha sido ´util en muchos descubrimientos, tambi´entiene limitaciones, como la gran cantidad de tiempo necesario para realizar detecciones de compa~neroslejanos a su estrella y la imposibilidad de medir la inclinaci´onde las ´orbitas.As´ı,esta t´ecnicas´olopermite medir la masa m´ınimade un compa~nero.El m´etodo de im´agenesdirectas, por otro lado, es m´assensible a la detecci´onde compa~nerosa distancias mas lejanas de sus estrellas primarias, debido al gran contraste de luminosidad entre compa~nerosde baja masa y sus estrellas. A´uncuando este m´etodo ha producido relativamente pocos descubrimientos, nos da la capacidad de mapear la orbita astrom´etricay medir la inclinaci´on.De esta forma, podemos combinar ambos m´etodos complementarios e investigar el r´egimenmasa-separaci´onentre sus detecciones. Surveys que utilizan la t´ecnicade velocidades radiales, a menudo presentan evidencia de perio- dos largos, en donde es posible que exista un compa~nerolejano que no se ha movido lo suficiente para poder determinar su ´orbitade manera precisa. En estos casos, podemos estudiarlos utilizando im´agenesdirectas. Para investigar el concepto de combinar estos dos m´etodos, utilizamos dichos periodos largos provenientes de surveys que utilizan velocidades radiales para luego observarlos utilizando instrumentos con ´opticaadaptativa (c´amarasy espectr´ografos)como VLT-SPHERE, Magellan AO y VLT-SINFONI. Se comprob´oel funcionamiento de este m´etodo en el descubrim- iento de un compa~neroestelar de tipo M3 a la estrella tipo Sol, rica en metales HD86006 y en el descubrimiento de dos enanas ultra fr´ıasde transici´onM/L orbitando la estrella de tipo M tem- prano que posee un planeta GJ 3634. De esta forma, podemos utilizar espectroscop´ıapara precisar sus caracter´ısticas, y con suficiente movimiento orbital, podemos utilizar astrometr´ıa para esti- mar masas din´amicas. Estos objetos pueden ser usados como referencia para estudiar la relaci´on masa-luminosidad-metalicidad, adem´asde servir como limite para los modelos evolutivos. Para investigar como mejorar el contraste de nuestras im´agenesdirectas, analizamos los efec- tos de dos t´ecnicasde post-procesamiento: im´agenesdiferenciales angulares ("angular differential imaging"; ADI), donde podemos aprovechar la rotaci´ondel campo durante una observaci´onpara hacer una colecci´onde datos referenciales con los que podemos sustraer la observaci´onde ciencia; e im´agenesdiferenciales de referencia ("reference differential imaging"; RDI), donde una similar (pero distinta) PSF puede ser usada como referencia en el objeto de inter´es.Encontramos que RDI produce el mejor resultado a separaciones peque~nasde la estrella. Podemos usar estas t´ecnicasjunto con nuestro survey de im´agenessin detecci´onde compa~neroscomo candidatos para instrumentos de futuros telescopios espaciales y terrestres para buscar peque~nosplanetas en ´orbitas cercanas en estrellas viejas similares al Sol. i ii RESUMEN DE LA MEMORIA PARA OPTAR AL T´ITULO DE DOCTOR EN CIENCIAS, MENCION´ ASTRONOM´IA POR: BLAKE M PANTOJA FECHA: 2019 PROF. GU´IA: JAMES JENKINS SAFARI: BRIDGING THE GAP BETWEEN RADIAL VELOCITY AND DIRECT IMAGING Radial velocities is a very productive method in the search of exoplanets starting with the landmark discovery of 51 Peg b in 1995 to the about 800 planets detected by the method today. Even though it has been advantageous in making many detections, the method has a few limitations as well, namely that extended amounts of time is needed to make detections of companions far from the star and that it is inherently impossible to constrain a compan- ion's inclination, thus limiting the technique to measuring a companion's minimum mass. Direct imaging, on the other hand, is more sensitive to the detection of companions distant from their primary stars, owing to the huge contrast in luminosity between close low-mass companions and their stars. While the method has been responsible for relatively few exo- planet discoveries, it provides the ability to map an astrometric orbit and find an inclination. We can thus combine these complementary methods and study the mass-separation regime between their detections. Radial velocity surveys turn up a number of long-period or linear trends where there is distant companion that has not moved enough for precise constraint of its orbit. As we know there to be a distant companion, we can follow up with imaging to search for it. To further investigate this concept of combining these methods, we used long-period trends as targets from planet-search radial velocity surveys to image with the adaptive optics imagers and spectrographs VLT-SPHERE, Magellan AO, and VLT-SINFONI. This concept is proved to work with the discoveries of an M3 companion to the metal-rich Sun-like star HD 86006 and of two M/L transition ultracool dwarfs orbiting the planet-hosting early M dwarf GJ 3634. Following these detections, we can use spectroscopy to constrain their characteristics, and with enough orbital motion, we can use astrometric measurements to constrain dynamical masses. These objects can be used as benchmarks to study the mass-luminosity-metallicity relation, as well as observational constraints on evolutionary models. To investigate into improving the contrast performance of our direct images, we studied the effects of the two post-processing techniques angular differential imaging (ADI), where the field rotation during an observation can be used to make a reference data set with which to subtract the science observation, and reference differential imaging (RDI), where a similar but separate point spread function can be used as a reference to the science target. We found RDI to provide the best result at short separations from the star. We can use the techniques along with our sample of imaging non-detections as targets for future space-based and ground-based imagers to search for close low-mass planets around old Sun-like stars. iii iv Agradecimientos First of all, I would like to thank my two advisors from Cal´anand ESO, James and Julien, who provided me with their expertise, knowledge, advice, and support. James helped me orient in a totally new country when I started this program while also being patient with my learning a new field of study, and Julien trained me firsthand in a more technical area of astronomy involving instrumentation in an observatory setting. Without them, this thesis and my PhD as a whole would not have been possible. I would also like to thank my committee including Paulina and Pato and I appreciate their taking the time to be a part of this work. I also want to thank my collaborators Arthur, Graeme, Mat´ıas,Ga¨el,Bartek, Mikko, Anne-Marie, Julien, and others. Thank all of you for all the support in my work. Thank you to Dr. Williger and Dr. Morrison for your support in my undergraduate studies. Y grac´ıasa Natalie, Marta, y Gissela por su paciencia en hacer las cosas administrativas. Y grac´ıasSra. Mari por el almuerzo diario. I would like to thank my Mom and Dad. They have each provided me the patience, perseverance, and love of learning that led me to go this far in my studies. Thank you for your support in my whole education, without which I could not have studied astronomy at the doctoral level. I also thank my brothers Corey and Landon and sister Marissa for being there with me while growing up and now. I also thank my aunts, uncles, cousins, grandpa y familia en Per´u.Y muchas gracias a mi abuelita. Es por ella que quer´ıaestudiar en un pa´ıs hispanofono. Being so far away from home, I have had the chance to meet new friends here in Chile as well as keep up with old friends. Thank you to my friends from other countries who also came to Chile including Sudeep, Valentin, Robert, Nina, Armin, Nathen, Carla, Jonathan, Alessandro, and Murat who really made a family away from home for me with unforgetable trips and times spent together. Muchas grac´ıasa mis amigos y compa~nerosde mi generaci´on Mat´ıas (tambi´engracias por la ayuda con este resumen en espa~nol!),Jorge, Juan, Seba, Grecco y Juanpi por su apoyo en mi primer a~no y el resto de mi doctorado y paciencia con mi espa~nolmalo. <Sin ustedes no ser´ıaposible! Tambi´ena mis otros amigos ac´aen Chile incluyendo Ricardo, Maritza, Paula, Pablo, Tere, Jos´e,Pato, Daniela, Bica, Gabriela, Gus, Seba, Piera, Mia, Alexander y Cambrilo por su consejo y apoyo en un pa´ısextranjero para m´ı. I want to thank my great friends back home who have stuck with me and gave me so much support through this long program away including Tommy, Doug, Dylan, Sadaf, Thomas, and Meena.