HST mid-cycle 30 to confirm a protoplanetary candidate in AS209 initially detected with MagAO-X-1114202963Assigned ID: 3816
----- Attempting Submission 1 (Mon Oct 17 16:25:38 GMT 2022) -----First Phase II submission for HST program 172831845793460----- Attempting Submission 1 (Thu Dec 15 02:41:36 GMT 2022) -----Confirming an accreting planet in a very young protoplanetary diskWe will attempt to confirm the detection of an accreting protoplanet detected after the Cycle 30 deadline with the MagAO-X instrument in a narrow-band H-alpha filter. The observations were taken under exceptional conditions, and it is highly unlikely that similar conditions will be met during a second epoch observation from the ground. The protoplanet, detected with >4 sigma fidelity, is located at ~1 arcsec from the central star, and it is accreting at a relatively low rate (Macc = 8.5 x 10^-9 MJ/yr assuming zero extinction).
The analysis will allow us to (1) confirm the existence of the accreting protoplanet, (2) investigate its accretion history, (3) search for indications of accretion variability, (4) provide valuable information to numerical simulations of planet formation and planet-disk interactions. Given the young age of the star (<1-2 Myr), the protoplanet candidate AS209c has the potential of revolutionize the field of planet formation, demonstrating that planets can form quickly at large separation from their star via disk instability. Indeed, core accretion requires much longer timescales for the protoplanet candidate to form.
We will use the narrow-band filter F656N of the HST/WFC3 instrument for 3 orbit in order to achieve the sensitivity necessary to confirm the companion detection.
If confirmed, this candidate would be HST's first bona fide discovery of a protoplanet.The primary goal of our observations is to use the direct-imaging technique to confirm the presence of an accreting gas giant planet in the disk surrounding AS209. We will observe each target using WFC3/UVIS with the F656N filter for three consecutive orbits. The F656N filter will capture the H-alpha emission from the accreting planets. For all observations, we will use the UVIS2-C512C-SUB subarray to reduce readout time and improve observing efficiency. The images will be taken using a box dithering pattern with a dithering distance of 0.02 arcsec (0.5 pixels) on both sides. This will allow reconstructing Nyquist-sampled images, which are necessary for the post-processing of high-contrast images. At each dithering position, several copies of exposures will be taken. The exposure time and iteration numbers are determined to maximize the point spread function signal to noise ratio, avoid saturation and maximize the usage of orbital visibility.
Every visit contains one orbit. Observations are linked by timing requirements and will be executed continuously. To facilitate two-roll angular differential imaging, the second visit will have a 25 to 35 degrees difference in telescope orientation compared to those of the first and third visits. The first and third visits will have the same orientation. The orientation constraints ensure that in no visit the planet signal (PA 196 deg) coincides with the position of one of the PSF spike.
Based on suggestions from STScI and the contact scientist on a similar program executed during the past cycles, we switch on the FLASH and set the level to 20 to mitigate the CTE loss, which has been aggravated in the past cycles.
Reduced gyro operations will affect this program only in relation to the orientation of the spacecraft compared to the position of the planet. It is crucial to avoid the diffraction spikes, where the noise caused by the PSF is larger. Thus, we included some tight constraints on the orientation of HST and reduced gyro mode might limit our schedulability.This proposal contains expertise in the observational and theoretical aspect of detecting and characterizing embedded planets. The team has extensive experience in both ground- and space-based observations, in particular with high contrast imaging of exoplanets.
PI Gabriele Cugno has broad expertise in direct imaging of young exoplanets, particularly those embedded in their natal disks. His past experience includes a ground-based survey to search for H-alpha signals from accreting protoplanet. He led the analysis of the MagAO-X data.
Co-I Yifan Zhou has PI'd several successful proposal to search for H-alpha emission from accreting planets with HST and will provide an excellent reduction of the HST data.
Co-I Michael Meyer led the initial MagAO-X proposal and has been involved in several ground- and space-based projects to unveil forming protoplanets with high-contrast imaging.
Co-I Jared Males is the Principal Investigator of the MagAO-X instrument and has broad experience in optical ground-based high-contrast imaging.
Co-Is Myriam Benisty, Per Calissendorff and Matthew De Furio have broad experience in the analysis of high-contrast imaging data of disks and young companions.
Co-Is Richard Teague, Stefano Facchini and Edwin Bergin are all experts of sub-mm interferometric observations of protoplanetary disks, in particular studying the gas dyanamics associated with planet-disk interactions. These will focus primarily on extracting the crucial properties of the circumstellar and circumplanetary disks and mass of AS 209c necessary to interpret the observed Halpha emission. Co-I Stefano Facchini is the PI of a JWST/NIRCam program (Prog. ID: 2487) to search for protoplanets in this system.
Co-I Jaehan Bae is an expert in the theory of planet-disk interactions and running 3D numerical simluations of planet formation and will provide access to state-of-the-art numerical simulations of planet-disk interactions for the analysis of the data.Exoplanets and Exoplanet Formation3falsefalsefalsefalsefalsetruefalseSUPPORTEDEXT-STARK V-IVPROTOPLANETARY DISKT TAURI STARYSOThis object was generated by the targetselector and retrieved from the SIMBAD database.J2000J2000WFC3/UVISImagingNoNoF656NPOS-TARGDITHER0.02LINE0.02falsefalse9040BOX1false/Users/gcugno/Job/Proposals/HST_Cycle30/midcycle/OP-cache/AS209_P2-v01.xmlTiming link suitability includes constraints ([02 After 01 by 0.0 to 0.1 days])The scheduling data was generated by CASM 30.3.CASM was run in Phase II mode.The orientation requirements are meant to avoid the PSF spikes to end up at the position of the planet. The planet is located at a position angle of 196 deg East of North.(Tic-Visit
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)true10From MagAO-X data (assuming the emission is constant in time) we know that continuum emission and H-alpha line emission have roughly similar intensity in filters 9nm wide. Considering V=11.3 mag in the continuum, and taking into account that the UVIS filter has a width 1/5 of the width of the MagAO-X filter (i.e., the continuum contribution in the HST data will be lower, while the H-alpha contribution remains unchanged), we estimated the flux measured by HST (see ETC). The exposure time to reach saturation is estimated to be 10 seconds. Given the large separation of the candidate, we plan to observe with exposures of 13 s, slightly saturating the PSF core. This will not affect our ability to center the image, as we can use the PSF spikes for that. This has been shown in past works on accreting exoplanets./Users/gcugno/Job/Proposals/HST_Cycle30/midcycle/OP-cache/AS209_P2-v02.xmlTiming link suitability includes constraints ([02 After 01 by 0.0 to 0.1 days] [03 After 02 by 0.0 to 0.1 days])The scheduling data was generated by CASM 30.3.CASM was run in Phase II mode.The orientation requirements are meant to avoid the PSF spikes to end up at the position of the planet. The planet is located at a position angle of 196 deg East of North.(Tic-Visit
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)true10/Users/gcugno/Job/Proposals/HST_Cycle30/midcycle/OP-cache/AS209_P2-v03.xmlTiming link suitability includes constraints ([03 After 02 by 0.0 to 0.1 days])The scheduling data was generated by CASM 30.3.CASM was run in Phase II mode.The orientation requirements are meant to avoid the PSF spikes to end up at the position of the planet. The planet is located at a position angle of 196 deg North through East.(Tic-Visit
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