A5020929757- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Molecular Spectroscopy and Structure
- Solar and Space Plasma Dynamics
- Spectroscopy and Laser Applications
- Laser-induced spectroscopy and plasma
- Isotope Analysis in Ecology
- Planetary Science and Exploration
- Atmospheric Ozone and Climate
- Space Exploration and Technology
- Global Energy and Sustainability Research
- Robot Manipulation and Learning
- Spacecraft and Cryogenic Technologies
- Advanced machining processes and optimization
- Enzyme Structure and Function
- Pulsars and Gravitational Waves Research
- Methane Hydrates and Related Phenomena
- Manufacturing Process and Optimization
- Atmospheric and Environmental Gas Dynamics
- Astronomical and nuclear sciences
Kavli Institute for Theoretical Sciences
2022-2024
Peking University
2022-2024
The University of Tokyo
2017-2024
Tsinghua University
2019-2024
Graduate School USA
2017
Understanding the processes of planet formation and accretion in young systems is essential to unraveling initial conditions planetary systems. The PDS 70 system, which hosts two directly imaged protoplanets, provides a unique laboratory for studying these phenomena, particularly through H-alpha emission commonly used tracer. We present multi-epoch observations examine variability signatures within this focusing on b c. Using Hubble Space Telescope narrowband imaging from 2020 2024, we...
Abstract A planetary growth rate, i.e., the mass accretion is a fundamental parameter in planet formation, as it determines planet's final mass. Planetary rates have been estimated using hydrogen lines, based on models originally developed for accreting stars, known flow model. Recently, Aoyama et al. introduced shock model an alternative mechanism line emission. However, remains unclear which more appropriate planets and substellar objects. To address this, we applied both to archival data...
We report a new evaluation of the accretion properties PDS~70b obtained with VLT/MUSE. The main difference from previous studies in Haffert et al. (2019) and Aoyama & Ikoma is mass rate. Simultaneous multiple line observations, such as H$\alpha$ H$\beta$, can better constrain physical an accreting planet. While we clearly detected emissions PDS~70b, no H$\beta$ were detected. estimate flux 3-$\sigma$ upper limit to be 2.3~$\times$~10$^{-16}$~erg~s$^{-1}$~cm$^{-2}$. ratio $F_{\rm...
Abstract Giant planets embedded in protoplanetary disks (PPDs) can create annulus density gaps around their orbits the type-II regime, potentially responsible for ubiquity of annular substructures observed PPDs. Although a substantial amount works studying planetary migration and gap properties have been published, they almost exclusively all conducted under viscous accretion disk framework. However, recent studies established magnetized winds as primary mechanism driving evolution, which...
Context. Emission lines that are indicative of active accretion have been observed for a number low-mass companions ( M < 30 Jup ) to stars. Line variability is ubiquitous on stellar accretors, but it has never characterized in detail companions. Such characterizations can offer insights into the mechanism at play. Aims. We aim characterize short-to-long-term H I Paschen β emission line two 10 wide orbits: GQ Lup b and GSC 06214-00210 b. also clarify their mechanisms. Methods. used J-band...
Recent observations of protoplanets embedded in circumstellar disks have shed light on the planet formation process. In particular, detection hydrogen Balmer-line (H{\alpha}) emission gives direct constraints late-stage accretion onto gas giants. Very recently Haffert et al. (2019) measured spectral line-widths, addition to intensities, H{\alpha} from two orbiting PDS 70. Here, we study these by applying radiation-hydrodynamic models shock-heated flow that Aoyama (2018) has developed. As a...
Accreting planets have been detected through their hydrogen-line emission, specifically H$\alpha$. To interpret this, stellar-regime empirical correlations between the H$\alpha$ luminosity $L_\mathrm{H\alpha}$ and accretion $L_\mathrm{acc}$ or rate $\dot{M}$ extrapolated to planetary masses, however without validation. We present a theoretical $L_\mathrm{acc}$--$L_\mathrm{H\alpha}$ relationship applicable shock at surface of planet. consider wide ranges rates masses use detailed...
Context. Accreting planetary-mass objects have been detected at H α , but targeted searches mainly resulted in non-detections. Accretion tracers the regime could originate from shock itself, making them particularly susceptible to extinction by accreting material. High-resolution ( R > 50 000) spectrographs operating should soon enable one study how incoming material shapes line profile. Aims. We calculate much gas and dust onto a planet reduce flux planetary surface they affect shape....
Abstract Accretion signatures from bound brown dwarf and protoplanetary companions provide evidence for ongoing planet formation, accreting substellar objects have enabled new avenues to study the astrophysical mechanisms controlling formation accretion processes. Delorme 1 (AB)b, a ∼30–45 Myr circumbinary planetary-mass companion, was recently discovered exhibit strong H α emission. This suggests circumplanetary disk, somewhat surprising given canonical gas disk dispersal timescales of 5–10...
Context. Accretion at planetary-mass companions (PMCs) suggests the presence of a protoplanetary disc in system, likely accompanied by circumplanetary disc. High-resolution spectroscopy accreting PMCs is very difficult due to their proximity bright host stars. For well-separated companions, however, such spectra are feasible and they unique windows into accretion. Aims. We have followed up on our observations 40-Myr, still accreting, circumbinary PMC Delorme 1 (AB)b. used high-resolution...
Abstract TWA 27B (2M1207b) is the first directly imaged planetary-mass ( M p ≈ 5 J ) companion and was observed at 0.9–5.3 μ m with JWST/NIRSpec. To understand accretion properties of 27B, we search for continuum-subtracted near-infrared helium hydrogen emission lines measure their widths luminosities. We detect He i triplet 4.3 σ all Paschen-series covered by NIRSpec (Pa α , Pa β γ δ 4 –5 . The three brightest Brackett-series (Br Br as well Pf are tentative detections 2 –3 provide upper...
Context. Intrinsic H$\alpha$ emission can be advantageously used to detect substellar companions because it improves contrasts in direct imaging. Characterising this from accreting exoplanets allows for the testing of planet formation theories. Aims. We characterise young circumbinary planetary mass companion 2MASS J01033563-5515561 (AB)b (Delorme 1 (AB)b) through medium-resolution spectroscopy. Methods. new narrow-field mode (NFM) MUSE integral-field spectrograph, located on ESO Very Large...
Abstract We present a near-infrared direct imaging search for accretion signatures of possible protoplanets around the young stellar object (YSO) TW Hya, multi-ring disk exhibiting evidence planet formation. The Pa β line (1.282 μ m) is an indication onto protoplanet, and its intensity much higher than that blackbody radiation from protoplanet. focused on performed Keck/OSIRIS spectroscopic observations. Although spectral differential (SDI) reduction detected no signatures, results study...
Abstract Recent high-sensitivity observations reveal that accreting giant planets embedded in their parental circumstellar disks can emit H α at final formation stages. While the origin of this emission is not yet determined, magnetospheric accretion currently most plausible hypothesis. In order to test hypothesis further, we develop a simplified but physics-based model and apply it our taken toward HD 163296 with Subaru/SCExAO+VAMPIRES. We specify under which conditions undergo hydrogen...
Forbidden emission lines in protoplanetary disks are a key diagnostic studies of the evolution disk and host star. We report spatially resolved lines, [OI] 6300, 6363, [NII] 6548, 6583, H$\alpha$, [SII] 6716, 6730 Angstrom that believed to be associated with jets magnetically driven winds inner disks. Observations were carried out optical integral field spectrograph Multi Unit Spectroscopic Explorer (MUSE), at Very Large Telescope (VLT). With resolution 0.025 X arcsec$^{2}$, we aim derive...
Abstract Accretion rates ( <?CDATA $\dot{M}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mo>̇</mml:mo> </mml:mover> </mml:math> ) of young stars show a strong correlation with object mass M ); however, extension the $\dot{M}\mbox{--}M$?> <mml:mo>–</mml:mo> relation into substellar regime is less certain. Here, we present Comprehensive Archive Substellar and Planetary Rates (CASPAR),...
Abstract Hydrogen lines from forming planets are crucial for understanding planet formation. However, the number of planetary hydrogen line detections is still limited. Recent JWST/NIRSpec observations have detected Paschen and Brackett at TWA 27 B (2M1207b). Although classified as a planetary- mass companison (PMC) rather than due to its large ratio central star, B’s emissions expected be same one, given small (≈5 M J ). We aim constrain accretion properties geometry B, contributing our...
GQ Lup B is a young and accreting, substellar companion that appears to drive spiral arm in the circumstellar disk of its host star. We report high-contrast imaging observations with VLT/NACO at 4-5 $\mu$m medium-resolution integral field spectroscopy VLT/MUSE. The optical spectrum consistent an M9 spectral type, shows characteristics low-gravity atmosphere, exhibits strong H$\alpha$ emission. $H-M'$ color $\gtrsim$1 mag redder than dwarfs similar types detailed analysis energy distribution...
Context . Accretion among planetary mass companions is a poorly understood phenomenon, due to the lack of both observational and theoretical studies. The detection emission lines from accreting gas giants facilitates detailed investigations into this process. Aims This work presents analysis Balmer one few known young, planetary-mass objects with observed emission, isolated L2 γ dwarf 2MASS J11151597+1937266 between 7 21 M Jup an age 5–45 Myr, located at 45 ± 2 pc. Methods We obtained first...
Progress in understanding of giant planet formation has been hampered by a lack observational constraints to growing protoplanets. Recently, detection an H{\alpha}-emission excess via direct imaging was reported for the protoplanet LkCa15b orbiting pre-main-sequence star LkCa15. However, physical mechanism H{\alpha} emission is poorly understood. According recent high-resolution three-dimensional hydrodynamic simulations flow accreting onto protoplanets, disk gas flows down almost vertically...
Abstract We present a high-contrast imaging search for Pa β line emission from protoplanets in the PDS 70 system with Keck/OSIRIS integral field spectroscopy. applied high-resolution spectral differential technique to OSIRIS J -band data but did not detect at level predicted using parameters of Hashimoto et al. (2020). This lack suggests MUSE-based study may have overestimated width H α . compared our detection limits previous flux and estimated A V be ∼0.9 2.0 b c, respectively. In...
Understanding how giant planets form requires observational input from directly imaged protoplanets. We used VLT/NACO and VLT/SPHERE to search for companions in the transition disc of 2MASS J19005804-3645048 (hereafter CrA-9), an accreting M0.75 dwarf with estimated age 1-2 Myr. found a faint point source at $\sim$0.7'' separation CrA-9 ($\sim$108 au projected separation). Our 3-epoch astrometry rejects fixed background star $5\sigma$ significance. The near-IR absolute magnitudes object...
Hydrogen-line emission from an accretion shock has recently been observed at planetary-mass objects. Our previous work predicted the spectrum and luminosity for a on circumplanetary disc. We extend this to planet-surface shock. calculate global spectral energy distribution (SED) of accreting planets by combining our model spectra with photospheric SEDs, predict line-integrated flux several hydrogen lines, especially H alpha, but also beta, Pa gamma, Br gamma. apply non-equilibrium surface...
Recent observations have detected excess H$\alpha$ emission from young stellar systems with an age of several Myr such as PDS 70. One-dimensional radiation-hydrodynamic models shock-heated flows that we developed previously demonstrate planetary accretion $>$ a few ten km s$^{-1}$ can produce emission. It is, however, challenge to understand the process proto-giant planets shock-originated because huge gap in scale between circumplanetary disk (CPD) and microscopic shock. To overcome...