Combing the Brown Dwarf Desert with APOGEE NICHOLAS TROUP UNIVERSITY OF VIRGINIA SESAPS 2016
Brown Dwarfs (BDs) Missing link between low mass stars and gas giant planets. Lack the mass to ignite Hydrogen fusion (~80 M jup ) Enough mass to fuse Deuterium (~13 M jup ) Image Credit: Joergens, Viki
Detecting Companions Orbiting companion tugs on host star Detect Doppler shifts in the star s spectrum. Measure periodic changes in the radial velocities (RV) of the star Fit orbital parameters to RV data: Period (P) Amplitude (K) Eccentricity (e) P K
The Brown Dwarf Desert 1000 s of planets and stellar companions now known Only a few dozen BD companions Paucity of BD companions extends out to 3 AU* Primarily Sun-like hosts *AU = Astronomical Unit = Avg. Distance between Earth and Sun Grether & Lineweaver 2006
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Purpose: Chemical and Kinematical Survey of the Milky Way Telescope: SDSS 2.5m @ Apache Point Observatory (APO) Instrument: R ~ 22,500 H-band (1.5-1.7 μm) Massively Multiplexed (300 fiber) Spectrograph Survey Length: 3 Years Stars Observed: >150,000 Data Products: - Radial Velocities for Every Visit - Stellar Parameters - -- - Chemical Abundances Requirements: - Final Combined Spectra with S/N ~ 100 Majewski, et al. 2015, sub.
Troup, et al. 2016 APOGEE s Search for RV Companions S/N of spectrum APOGEE survey requirements gives us: RV precision to detect close-in Jupiter-Mass Planets Heavy elements compared to Sun
Troup, et al. 2016 APOGEE s Search for RV Companions S/N of spectrum APOGEE survey requirements gives us: RV precision to detect close-in Jupiter-Mass Planets Baseline to detect companions with P < 3 years Heavy elements compared to Sun
Troup, et al. 2016 APOGEE s Search for RV Companions APOGEE survey requirements gives us: RV precision to detect close-in Jupiter-mass Planets Baseline to detect companions with P < 3 years 14,000 Stars with enough visits to fit orbits Visits to S/N>100 H Magnitude 1 7.0 H 11.0 3 7.0 H 12.2 6 12.2 < H 12.8 12 12.8 < H 13.3 24 12.8 < H 13.8 Targets outside This paradigm: + Tellurics + Calibration Targets + Ancillary Programs
Combing the Brown Dwarf Desert 382 Stars -- 376 with no previously known companions 213 Binaries 57 Hot Jupiters Troup, et al. 2016 112 BD Companions Jupiter
Combing the Brown Dwarf Desert Grether & Lineweaver 2006 382 Stars -- 376 with no previously known companions 213 Binaries 112 BD Companions 57 Hot Jupiters Troup, et al. 2016 Jupiter
Known BD Companions Adopted from Wilson, et al. 2016 Mars s Orbit Earth s Orbit Venus s Orbit Mercury s Orbit Sun
APOGEE BD Companion Candidates Mars s Orbit Adopted from Troup, et al. 2016 Earth s Orbit Venus s Orbit Mercury s Orbit Sun
Why is our Desert so Fertile? Catalog reproduces desert, but only out to 0.1-0.2 AU Traditionally: 3 AU and only G dwarfs* *G dwarf = A Star like the Sun
Why is our Desert so Fertile? Catalog reproduces desert, but only out to 0.1-0.2 AU Traditionally: 3 AU and only G dwarfs* Giants APOGEE = Cornucopia of stellar types Many giant/evolved stars Hotter/cooler dwarfs Why does this matter? F G More Dwarfs K M *G dwarf = A Star like the Sun Troup et al., 2016
Known BD Companions Adopted from Wilson, et al. 2016 Mars s Orbit Earth s Orbit Venus s Orbit Mercury s Orbit Sun
Known BD Companions Adopted from Wilson, et al. 2016 Mars s Orbit Earth s Orbit Venus s Orbit Mostly stars hotter/more massive than the Sun Mercury s Orbit Sun
The F dwarf Oasis BD desert exists for G dwarfs, but not F dwarfs* F dwarfs are rapid rotators = Suppressed tidal dissipation *F dwarf = Stars like the Sun, but a little hotter Guillot, et al. 2014
The F dwarf Oasis BD desert exists for G dwarfs, but not F dwarfs* F dwarfs are rapid rotators = Suppressed tidal dissipation More details on tidal interactions in the next talk. *F dwarf = Stars like the Sun, but a little hotter Guillot, et al. 2014
APOGEE BD Companion Candidates Mars s Orbit Adopted from Troup, et al. 2016 Earth s Orbit Venus s Orbit Mercury s Orbit Sun
The F dwarf Oasis BD desert exists for G dwarfs, but not F dwarfs* F dwarfs are rapid rotators = Suppressed tidal dissipation Most of the giants + in our sample evolved from F dwarfs Evidence for the F dwarf Oasis BD Desert a Special Case? *F dwarf = Stars like the Sun, but a little hotter + Giant stars = Dying stars that have exhausted H fusion and expanded in size Guillot, et al. 2014
BD Desert: A Special Case? Contribution of BDs to total number of companions decreases with primary mass BD Desert a Special Case of a more general lack of extreme mass ratio systems?
Binary Star Systems Planets A Continuum of Formation Mechanisms for BDs + Giants (Not shown) Credit: NASA, ESA, and A. Feild (STScI).
Conclusions and Future Work APOGEE has discovered 376 new companion candidates Over 100 are brown dwarfs A cornucopia of hosts (not just Sun-like) A much more fertile BD desert than previously found Related to they types of stars APOGEE observed Further evidence of the F dwarf oasis Moving Forward: Lots of follow up observations Continue this effort in 6-year extension of APOGEE2 and beyond Survey Baseline a (M * = M sun ) APOGEE-1 3 years 2 AU (>Mars) APOGEE-1+2 8-9 years 4 AU (>Ceres) APOGEE-1+2+AS4 13-15 years 6 AU (>Jupiter)
Acknowledgements Advisor & APOGEE PI - Steve Majewski UVa Theorists - Phil Arras, Zhi-Yun Li, Meng Sun APOGEE Hardware and Software Teams SDSS Management and Observers APOGEE RV Variability Team Nathan De Lee (NKU), Joleen Carlberg (STScI), David Nidever (UA), Kevin Covey (WWU), Joshua Pepper (Lehigh), Keivan Stassun (Vanderbilt), John Wisniewski (UO), Guy Stringfellow (CU), Scott Fleming (STSci), Chad Bender (UA), Johanna Teske (Carnegie), Carles Badenes (Pitt) and several others.