The First Habitable-zone Earth-sized Planet from TESS. II. Spitzer Confirms TOI-700 d

September 2020 • 2020AJ....160..117R

Authors • Rodriguez, Joseph E. • Vanderburg, Andrew • Zieba, Sebastian • Kreidberg, Laura • Morley, Caroline V. • Eastman, Jason D. • Kane, Stephen R. • Spencer, Alton • Quinn, Samuel N. • Cloutier, Ryan • Huang, Chelsea X. • Collins, Karen A. • Mann, Andrew W. • Gilbert, Emily • Schlieder, Joshua E. • Quintana, Elisa V. • Barclay, Thomas • Suissa, Gabrielle • Kopparapu, Ravi kumar • Dressing, Courtney D. • Ricker, George R. • Vanderspek, Roland K. • Latham, David W. • Seager, Sara • Winn, Joshua N. • Jenkins, Jon M. • Berta-Thompson, Zachory • Boyd, Patricia T. • Charbonneau, David • Caldwell, Douglas A. • Chiang, Eugene • Christiansen, Jessie L. • Ciardi, David R. • Colón, Knicole D. • Doty, John • Gan, Tianjun • Guerrero, Natalia • Günther, Maximilian N. • Lee, Eve J. • Levine, Alan M. • Lopez, Eric • Muirhead, Philip S. • Newton, Elisabeth • Rose, Mark E. • Twicken, Joseph D. • Villaseñor, Jesus Noel

Abstract • We present Spitzer 4.5 μm observations of the transit of TOI-700 d, a habitable-zone Earth-sized planet in a multiplanet system transiting a nearby M-dwarf star (TIC 150428135, 2MASS J06282325-6534456). TOI-700 d has a radius of ${1.144}_{-0.061}^{+0.062}{R}_{\oplus }$ and orbits within its host star's conservative habitable zone with a period of 37.42 days (Teq ∼ 269 K). TOI-700 also hosts two small inner planets (Rb = ${1.037}_{-0.064}^{+0.065}{R}_{\oplus }$ and Rc = ${2.65}_{-0.15}^{+0.16}{R}_{\oplus }$ ) with periods of 9.98 and 16.05 days, respectively. Our Spitzer observations confirm the Transiting Exoplanet Survey Satellite (TESS) detection of TOI-700 d and remove any remaining doubt that it is a genuine planet. We analyze the Spitzer light curve combined with the 11 sectors of TESS observations and a transit of TOI-700 c from the LCOGT network to determine the full system parameters. Although studying the atmosphere of TOI-700 d is not likely feasible with upcoming facilities, it may be possible to measure the mass of TOI-700 d using state-of-the-art radial velocity (RV) instruments (expected RV semiamplitude of ∼70 cm s-1).


IPAC Authors


Jessie Christiansen

Associate Scientist


David Ciardi

Senior Scientist