Wide Separation Planets in Time (WISPIT): Discovery of a Gap H<i>α</i> Protoplanet WISPIT 2b with MagAO-X
Laird M. Close, Richelle van Capelleveen, Gabriel Weible, Kevin Wagner, Sebastiaan Y. Haffert, Jared R. Males, Ilya Ilyin, Matthew A. Kenworthy, Jialin Li, Joseph D. Long, Steve Ertel, C. Ginski, Alycia J. Weinberger, Katherine B. Follette, Joshua Liberman, Katie Twitchell, Parker Johnson, Jay K. Kueny, Dániel Apai, René Doyon, Warren B. Foster, Victor Gasho, Kyle Van Gorkom, Olivier Guyon, Maggie Kautz, A. McLeod, Eden McEwen, Logan Pearce, Lauren Schatz, Alexander D. Hedglen, Ya-Lin Wu, J. W. Isbell, Jenny Power, Jared Carlson, Emmeline Close, Elena Tonucci, Matthijs Mars
Abstract
Abstract Excellent (<25 mas) H α images of the star TYC 5709-354-1 led to the discovery of a rare H α protoplanet. This star was discovered by the WISPIT survey to have a large multi-ring transitional disk, and is hereafter WISPIT 2. Our H α images of 2025 April 13 and 16 discovered an accreting (H α in emission) protoplanet: WISPIT 2b ( r = 309.43 ± 1.56 mas; (∼54 au deprojected), PA = 242 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>°</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 21 ± 0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>°</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 41) likely clearing a dust-free gap between the two brightest dust rings in the transitional disk. Our signal-to-noise ratio of 12.5 detection gave an H α ASDI contrast of (6.5 ± 0.5) × 10 −4 and an H α line flux of (1.29 ± 0.28) × 10 −15 erg s −1 cm −2 . We also present L ′ photometry from LBT/LMIRcam of the planet ( L ′ = 15.30 ± 0.05 mag), which, when coupled with an age of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>5</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mn>1</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> <mml:mo>.</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2</mml:mn> <mml:mo>.</mml:mo> <mml:mn>4</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> Myr, yields a planet mass estimate of 5.3 ± 1.0 M jup from the DUSTY evolutionary models. WISPIT 2b is accreting at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>2</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mn>25</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0</mml:mn> <mml:mo>.</mml:mo> <mml:mn>17</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>3</mml:mn> <mml:mo>.</mml:mo> <mml:mn>75</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> × 10 −12 M Sun yr −1 . WISPIT 2b is very similar to the other H α protoplanets in terms of mass, age, flux, and accretion rate. The inclination of the system ( i = 44°) is also, surprisingly, very similar to the other known H α protoplanet systems, which all cluster from 37° ≤ i ≤ 52°. We argue this clustering has only a ∼1.0% (2.6 σ ) probability of occurring randomly, and so we speculate that magnetospherical accretion might have a preferred inclination range (∼37°–52°) for the direct (cloud free, low extinction) line of sight to the H α line formation/shock region. We also find at 110 mas (∼15 au deprojected) a close companion candidate (CC1) that may be consistent with an inner dusty 9 ± 4 M jup planet.