Precision Stellar & Planetary Astrophysics with SPHEREx, Gaia & TESS Daniel J. Stevens OSU Presidential Fellow The Ohio State University
SPHEREx Synergies Workshop January 31, 2018 Know Thy Star, Know Thy Planet
● Precise, accurate stellar parameters needed to: ○ constrain planet interiors ○ calibrate empirical relations ● Often impose constraints on stellar params from models ○ Assumes models Gettel+(16) (and inputs to models) are accurate...not always true! M Dwarf Models: Too Small, Too Hot KELT J041621-620046 ● Underpredict radii by ~5% ≳ ○ Rp/R* precision of M dwarf transit surveys
● Overpredict T by similar KELT J041621-620046 eff amount ● What physics is missing? ● What’s the effect of binary companions? Lubin+ (17) M Dwarf Models: Too Small, Too Hot KELT J041621-620046 ● Underpredict radii by ~5% ≳ ○ Rp/R* precision of M dwarf transit surveys
● Overpredict T by similar KELT J041621-620046 eff amount ● What physics is missing? ● What’s the effect of binary companions? Lubin+ (17) The Bright Star (and M Dwarf) Opportunity with TESS
● TESS: ~100k eclipsing binaries and transiting planets
Golden opportunity for:
Sullivan+(15,17) ● characterizing stars & planets ● calibrating empirical relations ● testing models ● comparative exoplanetology We Need Precise:
● SED fitting: Radii, effective temperatures ○ SPHEREx, Gaia spectrophot.; broad-band photometry ● SED + transits + RVs: EB masses, radii, temperatures ○ TESS, PLATO, Kepler/K2 ○
(see Stevens, Gaudi, & Stassun, in review; arXiv:1712.05046) We Need Precise:
● SED fitting: Radii, effective temperatures ○ SPHEREx, Gaia spectrophot.; broad-band photometry ● SED + transits + RVs: EB masses, radii, temperatures ○ TESS, PLATO, Kepler/K2, ground-based follow-up ○
(see Stevens, Gaudi, & Stassun, in review; arXiv:1712.05046) Parameters from Single-lined EBs ▪ Measure period P, depth , durations T, Winn (2010) → a/(R1+R2), R2/R1
▫ Infer primary’s density ⍴: Ingress duration Depth ▪ RV semiamplitude K:
No individual masses or radii; FWHM need more constraints (SED!) duration Gaia Parallaxes Give Stellar Radii ● Fit for bolometric flux & extinction:
GALEX Bolometric flux (SED) Tycho-2, WISE W1-W4 FUV APASS... 2MASS Parallax NUV JHK
(Gaia)
Effective temperature (SED; spectra) ● Can be performed in bulk for bright stars* ○ GALEX, Tycho-2, APASS, 2MASS, WISE: *e.g. Stevens, Stassun, & All-sky & data already exist! Gaudi (2017) Gaia: Exquisite Distances
as) ● 5-10 micro-arcsec precision expected for bright stars
→ 0.1% uncertainty at KELT targets 300 pc End-of-mission parallax error ( Gaia G-band magnitude (ESA) T , Ingress Duration Dominate Errors
eff
Gaia M 1 M 2 Gaia parallaxes contribute negligibly. Error (%)
Parallax Error (%)
Teff contributes greatly: R 1 -2 R1 ~ Teff R 2 3
Error (%) M1 ~ R1 T Error (%) -6 eff → M ~ T 1 eff
Stevens, Gaudi, & Stassun Ground-based (in review; arXiv:1712.05046) transits Precise ingress/egress
Error (%) durations: tough from Ingress Duration Error (%) the ground... Precise Stellar Densities with TESS
▪ Densities at the Density uncertainty dominates mass couple-percent uncertainties level
▪ With <1% R1: ▫ M to < 5% 1 4% ▫ M to < 3% (required for 2 Teff, radius (w/ precise RVs) <5% masses uncertainties (w/ 1% radius) dominate ▪ Are <1% radii achievable? Example SEDs with Broad-band Photometry
Measure 68% of total flux Mid-A Dwarf Early-M Dwarf
Measure 40% of total flux
Measure 68% of total flux Late-F Dwarf Example SEDs with SPHEREx and Gaia
Measure 90% of total flux
Mid-A Dwarf Early-MEarly-M Dwarf Dwarf
Measure 99% of total flux!
Measure 98% of total flux!
Late-F Dwarf Ex: Mid-A Dwarf (V ~ 10)
Par. Broad-band + Gaia + SPHEREx
AV 0.15 + 0.05 0.09 + 0.03 0.069 + 0.014
Teff (K) 8000 + 130 (2%) 7900 + 100 (1%) 8000 + 11* (0.1%) 2x10-9 + 8x10-11 F (cgs) 2x10-9 + 10-10 (5%) 2x10-9 + 3x10-11 (2%) bol (4%)
R* (R☉) 2.17 + 0.06 (3%) 2.20 + 0.05 (2%) 2.10 + 0.01 (0.5%) Ex: F Dwarf (KELT-3; V ~ 10)
Par. Broad-band + Gaia + SPHEREx
AV 0.04 + 0.01 0.037 + 0.01 0.036 + 0.007
Teff (K) 6300 + 100 (2%) 6290 + 50 (0.8%) 6265 + 15* (0.2%)
-9 -10 -9 -11 -9 -11 Fbol (cgs) 3x10 + 10 (3%) 3x10 + 5x10 (2%) 3x10 + 2x10 (0.6%)
R* (R☉) 1.59 + 0.04 (2%) 1.62 + 0.02 (1%) 1.589 + 0.005 (0.3%)
*Teff from NextGen, Kurucz model atmospheres differ by 20 K Ex: Early M Dwarf (NGTS-1; V ~ 16)
Par. Broad-band + Gaia + SPHEREx
AV 0.04 + 0.01 0.034 + 0.003 0.036 + 0.005
Teff (K) 3900 + 50 (1%) 3888 + 25 (0.6%) 3912 + 8* (0.2%)
-11 -12 -11 -13 -11 -13 Fbol 5x10 + 2x10 5x10 + 9x10 4x10 + 3x10 (cgs) (4%) (2%) (0.6%)
R* (R☉) 0.58 + 0.03 (5%) 0.582 + 0.014 (2%) 0.570 + 0.005 (0.8%) Putting it Together:
Broad-band phot:
○ 6% Fbol
○ 4% R1
○ 14% M* + SPHEREx + Gaia:
○ <2% Fbol
○ <1% Teff
○ <1% R1 + TESS: ○ 2% density
○ 2% M* AV = 0.0 Able to explore systematics in model atmospheres...
AV = 0.0 ...and to measure AV = 1.0 extinction Gaia “Cardelli-free!” SPHEREx Gaia+SPHEREx with SPHEREx Dan’s Deliverables Wish List
● Reduced spectrophotometry ○ Per-element wavelength, mag/flux, error (covariances?) ● Cross-matched catalogs or queryable database (IPAC!) ● Postage stamps and quality flags ○ Saturation, blending, upper limits The Next Era of Precision Stellar Astrophysics ● Bright, single-lined EBs will be benchmarks for: ○ Testing stellar and planetary models ○ Comparative exoplanetology ○ Galactic archaeology with abundances (Milky Way Mapper) and six phase-space coordinates (Gaia) ● SPHEREx spectrophotometry will enhance or enable:
○ Stellar radius/Teff precision ○ Atmosphere model tests → radius/Teff accuracy ○ Empirical interstellar reddening determination Bonus Slides! Secondary Eclipses with TESS Precise secondary eclipse depths probe
Teff suppression
M-M EBs KELT J041621-620046
Lubin+ (17) M dwarfs in the best-characterized double-lined EBs to date:
KELT J041621-620046 KELT J041621-620046
Adapted from Lubin+(17) ...plus 73 KELT SB1s in the southern ecliptic with TESS photometry: Ex: KELT-11 Beatty, Stevens+(17) (Pepper+16) ▪ Highly inflated Saturn around retired A star ~7 hours
▪ Can test stellar models & empirical relations: Parameter Spitzer+Ground+Torres Spitzer+Ground+Final Gaia
Stellar Mass (M☉) 1.44 ± 0.07 (5%) 1.80 ± 0.07 (4%)
Stellar Radius (R☉) 2.69 ± 0.04 (1%) 2.90 ± 0.02 (0.7%)
Planet Mass (MJup) 0.17 ± 0.02 (9%) 0.22 ± 0.02 (9%)
Planet Radius (RJup) 1.35 ± 0.10 (7%) 1.51 ± 0.09 (6%) Ex: F-M Eclipsing Binaries
● ~4.6-day, circular ● ~16-day, eccentric
Kepler CROW (Ic)
short-cadence
MORC (i’)
~10 hours Flux + Offset Normalized Flux
WCO (I) Time - Tc (hours) Time - Tc (hours) Preliminary Results Assuming 7 micro-arcsecond parallax error: Parameter Short-period EB Long-period EB
Primary Mass (M☉) 1.563 + 0.060 (4%) 1.350 + 0.110 (8%)
Primary Radius (R☉) 2.014 + 0.024 (1%) 1.704 + 0.029 (2%)
Secondary Mass (M☉) 0.216 + 0.006 (3%) 0.221 + 0.013 (6%)
Secondary Radius (R☉) 0.228 + 0.003 (1%) 0.258 + 0.012 (5%) Transit observables dominate mass uncertainties Double-lined EBs: The Gold Standard ▪ Eclipses + 2 RV orbits
→radii & masses Fully Convective ▪ < 3% precision ▪ Few with [Fe/H]
▪ M dwarf challenges:
▫ Dimness, flares, spots... 95 binaries from Torres+(10) Single-lined EBs: A New Gold Standard Like Double-lined EBs: Unlike Double-lined EBs: ● Found for free by ▪ Exoplanets! exoplanet transit/RV ▪ One set of (optical) surveys spectral lines
● Mass, radius of each ▫ Easier primary log(g), Teff, component is measured abundances ▫ Need more than (nearly) empirically RV+eclipse for masses, radii...