The Dead Moons of Aldebaran b

Benjamin Pope

NASA Sagan Fellow, NYU

Slides available at
benjaminpope.github.io/talks/aot/aot

Aldebaran

α Tauri

الدبران ,the follower

Hatzes & Cochran, 1993 claimed a detection of a \(628.96 \pm 0.90\) d planet around Aldebaran

finally confirmed in Hatzes et al., 2015!

All Data

A reanalysis of this data by Will Farr (Flatiron) detects additional variation with a ~ 6 day period

GP PSD
Stars ring like bells, with acoustic and buoyancy oscillations.

l=2, m=2 oscillation

Their frequencies tell us about stellar interior structure.

Frequencies of the Sun's 5-minute oscillations

Helioseismic Power Spectrum

Can we confirm this with Kepler?

Too bright to look at with Kepler!

What if we just look at unsaturated pixels?

Yes! We get the same frequency with K2!

Aldebaran K2 Light Curve
Without this asteroseismology, we have

\[M = 1.27^{+0.24}_{-0.20} \, \mathrm{M_{\odot}}\] and age \(4.9^{+3.6}_{-2.0} \, \rm Gyr \)
With this new constraint, we have

\[M = 1.16^{+0.07}_{-0.07} \, \mathrm{M_{\odot}}\] and age \(6.4^{+1.4}_{-1.1} \, \rm Gyr \)

Fitting stellar models, we find that on the main sequence Aldebaran b orbited at \(1.50 \pm 0.03 \) AU and the star had a luminosity \(2.0 \pm 0.7 \, L_\odot \)...

so Aldebaran b had an insolation comparable to Earth when its star was on the main sequence.