| Proposal Number | Subject Category | PI Name | Chandra Time | Title |
|---|---|---|---|---|
| 25200528 | STARS AND WD | Thomas Ayres | 104 ks | Activity at the Edge |
| 25200530 | STARS AND WD | Catherine Espaillat | 25 ks | A multiwavelength study of protoplanetary disk ionization |
Subject Category: STARS AND WD
Proposal Number: 25200528
Title: Activity at the Edge
PI Name: Thomas Ayres
Abstract: This is the Chandra part of a joint HST/Chandra program to obtain X-ray intensities and FUV spectra of 17 F5-G1 dwarf stars in the nearby 100-Myr-young Pleiades cluster. The objective is to test an aspect of the roto-convective magnetic dynamo, responsible for high-energy surface activity on Sunlike stars. The test involves the Rossby number, a ratio of the stellar rotation period to a convective turn-over time, which plays a key role in stellar (and terrestrial) dynamo theories. Empirical turn-over times can be estimated according to a correlation between a combined X-ray+FUV flux and the Rossby number, and then compared to models. However, there is a lack of suitable examples in the crucial range F5-G1, which this proposal seeks to remedy. Sixteen 6.5 ks pointings are proposed.
Subject Category: STARS AND WD
Proposal Number: 25200530
Title: A multiwavelength study of protoplanetary disk ionization
PI Name: Catherine Espaillat
Abstract: We aim to determine whether the magnetorotational instability (MRI) could be the elusive driver of turbulent accretion in protoplanetary disks. To accomplish this, we will measure the amount of X-ray induced disk ionization in a sample of three protoplanetary disks, leveraging the unique synergy provided by Chandra, HST, and JWST to measure simultaneously X-ray through UV luminosities and the fluxes of mid-infrared [Ne II] and [Ne III] fine structure lines. When combined with thermochemical modeling, these simultaneous Chandra, HST, and JWST observations will characterize the high-energy radiation spectrum impinging on the disk and lead to a measurement of the disk ionization fraction, which will test if the MRI is responsible for accretion in protoplanetary disks.