成長中の惑星を初めて暗黒のリング内で撮影（A growing baby planet photographed for first time in a ring of darkness）

2025-08-26 アリゾナ大学

Laird Close, University of Arizona

＜関連情報＞

• https://news.arizona.edu/news/growing-baby-planet-photographed-first-time-ring-darkness
• https://iopscience.iop.org/article/10.3847/2041-8213/adf7a5
• https://iopscience.iop.org/article/10.3847/2041-8213/adf721

時間軸における広間隔惑星（WISPIT）：MagAO-XによるギャップHα原始惑星WISPIT 2bの発見 Wide Separation Planets in Time (WISPIT): Discovery of a Gap Hα Protoplanet WISPIT 2b with MagAO-X

Laird M. Close, Richelle F. van Capelleveen, Gabriel Weible, Kevin Wagner, Sebastiaan Y. Haffert, Jared R. Males, Ilya Ilyin, Matthew A. Kenworthy, Jialin Li, Joseph D. Long,…
The Astrophysical Journal Letters  Published: 2025 August 26
DOI:10.3847/2041-8213/adf7a5

Abstract

Excellent (<25 mas) Hα images of the star TYC 5709-354-1 led to the discovery of a rare Hα protoplanet. This star was discovered by the WISPIT survey to have a large multi-ring transitional disk, and is hereafter WISPIT 2. Our Hα images of 2025 April 13 and 16 discovered an accreting (Hα in emission) protoplanet: WISPIT 2b (r = 309.43 ± 1.56 mas; (∼54 au deprojected), PA = 242:21 ± 0:41) 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 Hα ASDI contrast of (6.5 ± 0.5) × 10⁻⁴ and an Hα 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 5.1^+2.4_-1.3 Myr, yields a planet mass estimate of 5.3 ± 1.0 M_jup from the DUSTY evolutionary models. WISPIT 2b is accreting at 2.25^+3.75_-0.17 × 10⁻¹² M_Sun yr⁻¹. WISPIT 2b is very similar to the other Hα 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 Hα protoplanet systems, which all cluster from 37° ≤ i ≤ 52°. We argue this clustering has only a ∼1.0% (2.6σ) 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 Hα 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.

時間的に広く分離した惑星（WISPIT）：若い太陽型星WISPIT 2を回る多環状円盤における隙間除去惑星 WIde Separation Planets In Time (WISPIT): A Gap-clearing Planet in a Multi-ringed Disk around the Young Solar-type Star WISPIT 2

Richelle F. van Capelleveen, Christian Ginski, Matthew A. Kenworthy, Jake Byrne, Chloe Lawlor, Dan McLachlan, Eric E. Mamajek, Tomas Stolker, Myriam Benisty, Alexander J. Bohn,…
The Astrophysical Journal Letters  Published: 2025 August 26
DOI:10.3847/2041-8213/adf721

Abstract

In the past decades, several thousand exoplanet systems have been discovered around evolved, main-sequence stars, revealing a wide diversity in their architectures. To understand how the planet formation process can lead to vastly different outcomes in system architecture, we have to study the starting conditions of planet formation within the disks around young stars. In this study, we are presenting high-resolution direct imaging observations with the Very Large Telescope/SPHERE of the young (∼5 Myr), nearby (∼133 pc), solar-analog designated as WISPIT 2 (= TYC 5709-354-1). These observations were taken as part of our survey program that explores the formation and orbital evolution of wide-separation gas giants. WISPIT 2 was observed in four independent epochs using polarized light and total intensity observations. They reveal for the first time an extended (380 au) disk in scattered light with a multi-ringed substructure. We directly detect a young protoplanet, WISPIT 2b, embedded in a disk gap and show that it is comoving with its host star. Multiple SPHERE epochs demonstrate that it shows orbital motion consistent with Keplerian motion in the observed disk gap. Our H– and K_s-band photometric data are consistent with thermal emission from a young planet. By comparison with planet evolutionary models, we find a mass of the planet of  4.9^+0.9_-0.6M_Jup. This mass is also consistent with the width of the observed disk gap, retrieved from hydrodynamic models. WISPIT 2b is the first unambiguous planet detection in a multi-ringed disk, making the WISPIT 2 system the ideal laboratory to study planet–disk interaction and subsequent evolution.