The First Habitable-zone Earth-sized Planet from TESS. II. Spitzer Confirms TOI-700 d
Barclay, Thomas; Vanderburg, Andrew; Latham, David W.; Quinn, Samuel N.; Muirhead, Philip S.; Lee, Eve J.; Kane, Stephen R.; Schlieder, Joshua E.; Kreidberg, Laura; Collins, Karen A.; Ricker, George R.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Caldwell, Douglas A.; Günther, Maximilian N.; Ciardi, David R.; Mann, Andrew W.; Morley, Caroline V.; Rodriguez, Joseph E.; Colón, Knicole D.; Eastman, Jason D.; Huang, Chelsea X.; Levine, Alan M.; Twicken, Joseph D.; Boyd, Patricia T.; Vanderspek, Roland K.; Gan, Tianjun; Guerrero, Natalia; Dressing, Courtney D.; Charbonneau, David; Zieba, Sebastian; Christiansen, Jessie L.; Doty, John; Gilbert, Emily; Newton, Elisabeth; Quintana, Elisa V.; Cloutier, Ryan; Rose, Mark E.; Chiang, Eugene; Berta-Thompson, Zachory; Lopez, Eric; Villaseñor, Jesus Noel; Spencer, Alton; Suissa, Gabrielle; Kopparapu, Ravi kumar
United States, Sweden, Austria, Spain, China, Canada
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).