Frequency of low-mass exoplanets. . what about the non -detections? SIMON O’TOOLE (AAO/HERTFORDSHIRE), CHRIS TINNEY, JEREMY BAILEY, ROB WITTENMYER (UNSW), PAUL BUTLER (CARNEGIE), BRAD CARTER (SOUTHERN QUEENSLAND) Hugh Jones
Planet mass function Earth Neptune Jupiter
Exoplanet distributions
AAPS (Anglo-Australian Planet Search) Nearly 300 nights over last 10 years on 250, V< 7. 7 F, G, K, M IV, V stars selected on Ca. HK and observed with S/N=200 has yielded more than 30 nearby exoplanets (and 18 spectroscopic binaries) Recent programme of operational upgrades Observing sequencer Automated iodine cell Exposure meter Near future – fibre feed
Many ‘noise’ components e. g. , asteroseismological signal
asteroseismological signal function of L/M Based on Sun, Kjeldsen et al. 2008, Alpha Cen A varies by ~20% plus ~10% over Solar cycle
Strategy continuous long blocks of telescope time
48 night run on 24 bright stars
Exoplanets
Development of robust simulation system for AAPS data ¯ ¯ ¯ Use AAPS time stamps and internal errors Log 10 P = 0. 3, 0. 6, 0. 9, 1. 2 (or 2 to 20 days) e = 0. 0 -0. 2 in steps of 0. 1 Mass = 0. 02, 0. 05, 0. 1, 0. 2, 0. 5 MJ 7, 200 simulations/dataset ¯ Detectability criteria RMS (sim) < RMS (res) Km > 2 d. K + RMS (res) Pm > 2 d. P Chi 2 < 3 works for detections of HD 16417 and HD 4308
Differences between by star-by-star simulations
Differences between by star-by-star simulations
Detectability on 48 night run
Detectability sensitive to mass function 0. 01 -10 MJ lines of increasing thickness
Mass function d. N/d. M ~M-1 (~17% of planets host planets with >3 ME and <16 days)
Conclusions ¯ Simulation system can provide assessment of exoplanetary architectures based on RV data ¯ With multiple telescopes and long campaigns (1 m/s precision) can constrain ¬Saturn mass planets out to 6 AU ¬Neptune mass planets out to 1 AU ¬Super-Earths out to 0. 3 AU ¬Earth-mass planets out to 0. 1 AU
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