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Discovery and mass measurements of a cold, 10 earth mass planet and its host star

journal contribution
posted on 2023-05-17, 09:17 authored by Muraki, Y, Han, C, Bennett, DP, Suzuki, D, Monard, LAG, Street, R, Jorgensen, UG, Kundurthy, P, Skowron, J, Becker, AC, Albrow, MD, Fouque, P, Heyrovsky, D, Barry, RK, Beaulieu, JP, Wellnitz, DD, Bond, IA, Sumi, T, Dong, S, Gaudi, BS, Bramich, M, Dominik, M, Abe, F, Botzler, CS, Freeman, M, Fukui, A, Furusawa, K, Hayashi, F, Hearnshaw, JB, Hosaka, S, Itow, Y, Kamiya, K, Korpela, AV, Kilmartin, PM, Lin, W, Ling, CH, Makita, S, Masuda, K, Matsubara, Y, Miyake, N, Nishimoto, K, Ohnishi, K, Perrott, YC, Rattenbury, NJ, Saito, T, Skuljan, L, Sullivan, DJ, Sweatman, WL, Tristram, PJ, Wada, K, Yock, PCM, Christie, GW, DePoy, DL, Gorbikov, E, Gould, A, Kaspi, S, Lee, CU, Mallia, F, Maoz, D, McCormick, J, Moorhouse, D, Natusch, T, Park, BG, Pogge, RW, Polishook, D, Shporer, A, Thornley, G, Yee, JC, Allan, A, Browne, P, Horne, K, Kains, N, Snodgrass, C, Steele, I, Tsapras, Y, Batista, V, Bennett, CS, Brillant, S, Caldwell, JAR, Cassan, A, Andrew ColeAndrew Cole, Corrales, R, Coutures, C, Dieters, S, Prester, DD, Donatowicz, J, Greenhill, J, Kubas, D, Marquette, JB, Martin, R, Menzies, J, Sahu, KC, Waldman, I, Williams, A, Zub, M, Bourhrous, H, Matsuoka, Y, Nagayama, T, Oi, N, Randriamanakoto, Z, Bozza, V, Burgdorf, MJ, Novati, SC, Dreizler, S, Finet, F, Glitrup, M, Harpsoe, K, Hinse, TC, Hundertmark, M, Liebig, C, Maier, G, Mancini, L, Mathiasen, M, Rahvar, S, Ricci, D, Scarpetta, G, Skottfelt, J, Surdej, J, Southworth, J, Wambsganss, J, Zimmer, F, Udalski, A, Poleski, R, Wyrzykowski, L, Ulaczyk, K, Szymanski, MK, Kubiak, M, Pietrzynski, G, Soszynski, I
We present the discovery and mass measurement of the cold, low-mass planet MOA-2009-BLG-266Lb, performed with the gravitational microlensing method. This planet has a mass of mp = 10.4 ± 1.7 M⊕ and orbits a star of mass M sstarf = 0.56 ± 0.09 Msun at a semimajor axis of $a = 3.2{+1.9\atop -0.5}$ AU and an orbital period of $P = 7.6{+7.7\atop -1.5}$ yrs. The planet and host star mass measurements are enabled by the measurement of the microlensing parallax effect, which is seen primarily in the light curve distortion due to the orbital motion of the Earth. But the analysis also demonstrates the capability to measure the microlensing parallax with the Deep Impact (or EPOXI) spacecraft in a heliocentric orbit. The planet mass and orbital distance are similar to predictions for the critical core mass needed to accrete a substantial gaseous envelope, and thus may indicate that this planet is a "failed" gas giant. This and future microlensing detections will test planet formation theory predictions regarding the prevalence and masses of such planets.


Publication title

The Astrophysical Journal: An International Review of Astronomy and Astronomical Physics



Article number









School of Natural Sciences


Institute of Physics Publishing Inc

Place of publication

United States

Rights statement

Copyright 2011 The American Astronomical Society.

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Expanding knowledge in the physical sciences

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