01 / Contract Profile

80NSSC21K0571 Federal Contract Award

Agency code 8000

WE LEARNED FROM THE NASA KEPLER AND K-2 MISSIONS THAT BETWEEN ~20-50% OF MAIN SEQUENCE STARS HOST SMALL PLANETS (HAVING A RADIUS BETWEEN 1-4 EARTH RADII). DESPITE THE SHORT ORBITAL PERIODS OF MOST OF THESE TRANSITING PLANET DETECTIONS, SIMILAR DETECTIONS OF SMALL MASS PLANETS HAVE ELUDED RADIAL VELOCITY (RV) SURVEYS. ROCKY PLANETS, EVEN ON SHORT ORBITS, INDUCE STELLAR VELOCITIES SMALLER THAN THE 1-2 M/S PRECISION OF THE PREVIOUS GENERATION OF RADIAL VELOCITY INSTRUMENTS. WITH ADDITIONAL NOISE FROM STELLAR PHOTOSPHERES AND TYPICAL RV OBSERVING CADENCES, EVEN MINI-NEPTUNES ON MONTHS LONG ORBITS COULD HAVE BEEN MISSED. THIS PROJECT WILL RECONCILE THE DIFFERENT PLANET POPULATIONS AT PERIODS LESS THAN 100 DAYS SEEN BY TRANSIT AND RADIAL VELOCITY SURVEYS BY COMBINING DRAMATICALLY IMPROVED RADIAL VELOCITY PRECISION WITH AN EXTENDED HIGH CADENCE OBSERVING PROGRAM. WE WILL ALSO SAMPLE THE OCCURRENCE RATE OF LOW MASS PLANETS AT PERIODS LONGER THAN 100 DAYS THAT WILL BE LEFT UNEXPLORED BY CURRENT TRANSIT SURVEYS. IT IS IN THIS SPACE WHERE EARTH-LIKE PLANETS AT HABITABLE ZONE DISTANCES MAY BE FOUND AROUND G AND K STARS. THE EXTREME PRECISION SPECTROGRAPH (EXPRES) (JURGENSON ET AL. 2016) HAS DEMONSTRATED DOPPLER PRECISION OF BETTER THAN 30 CM/ S (BLACKMAN ET AL. 2020, PETERSBURG ET AL. SUBMITTED). THIS PRECISION IS SUFFICIENT TO DETECT THE TYPE OF SMALL ROCKY PLANETS DETECTED BY KEPLER. EXPRES IS ON THE 4.3 METER, LOWELL DISCOVERY TELESCOPE (LDT) WHERE WE HAVE UP TO 70 NIGHTS/YEAR THAT CAN BE SPLIT AS SMALL AS QUARTER NIGHTS FOR NEARLY 200 NIGHTS ON-SKY AFTER ACCOUNTING FOR NORMAL LOSSES DUE TO WEATHER. MORE THAN 2 YEARS AT THAT CADENCE ARE ALREADY BANKED WITH LOWELL OR HAVE FIRM COMMITMENTS FROM OUTSIDE FUNDING IN ADDITION TO THE YEAR OF SCIENCE OBSERVATIONS ALREADY OBTAINED. OUR PROGRAM TARGETS A ROTATING LIST OF 45 STARS THAT WE OBSERVE AT HIGH CADENCE FOR SEVERAL WEEKS BEFORE SPACING THEM OUT TO WEEKLY OBSERVATIONS, ALL AT SNR~500. THIS STRATEGY HAS ALREADY RESULTED IN THE DETECTION OF A SHORT PERIOD MINI-NEPTUNE (BREWER ET AL. IN PREP) AROUND A STAR WITH ~20 YEARS OF KECK HIRES OBSERVATIONS. THE HIGH PRECISION, HIGH RESOLUTION, AND HIGH CADENCE OF OUR SURVEY WITH EXPRES ALSO ENABLES CHARACTERIZATION OF PLANETS AND THEIR HOST STARS. WE WILL BE MEASURING SPIN-ORBIT ALIGNMENTS AND ATMOSPHERES OF SMALL PLANETS AND CHARACTERIZING THE BEHAVIOR OF STELLAR PHOTOSPHERES. WE HAVE DETECTED FE II IN THE TRANSIT SPECTROSCOPY FOR A HOT JUPITER AND MEASURED THE ROSSITER-MCLAUGHLIN EFFECT FOR A SMALL PLANET ORBITING A BRIGHT STAR. THESE DISCOVERIES REVEAL THE INTRINSIC NATURE OF PLANETS, PROVIDING HINTS ABOUT FORMATION AND EVOLUTION. CO-I LLAMA WILL ALSO BE ADDING AN ADDITIONAL 10-15 NIGHTS/YEAR FOR RV FOLLOW-UP CHARACTERIZATION OF TESS PLANETS. FINDING AND CHARACTERIZING HABITABLE EXOPLANETS IS ONE OF THE PRIMARY GOALS OF NASA'S EXOPLANET EXPLORATION PROGRAM (EXEP) SCIENCE PLAN. RECONCILING TEMPERATE ROCKY PLANET OCCURRENCE RATES, AND INDEED ALL PLANETARY ARCHITECTURES, BETWEEN TRANSIT AND RADIAL VELOCITY SURVEYS IS SPECIFICALLY IDENTIFIED AS A PRIORITY IN THE EXEP SCIENCE GAP LIST. THIS PROJECT WILL BE UNIQUE IN DETECTING LOW MASS PLANETS THAT HAVE ELUDED OTHER LOWER PRECISION RV SURVEYS AND WILL IMPROVE OUR UNDERSTANDING OF THE COMPLEXITY OF MULTI-PLANET ARCHITECTURES.