|Proposal Number||Subject Category||PI Name||Target Name||Total Chandra Time||Title|
|14200978||Extra-Solar Planets||David Ehrenreich||GJ 436b||60ks||Properties and dynamics of the upper atmosphere of the hot- Neptune GJ 436b|
|14500977||Hot Stars||Oleg Kargaltsev||Crab PWN||10ks||Multiwavelength spectra of the fine structure of the Crab|
|14910976||ISM and Circumstellar Matter||Yangsen Yao||4U 0512-401||200ks||Multiwavelength Spectroscopy of the Interstellar Medium: O and Ne Abundance ratio|
Subject Category: Extra-Solar Planets
Proposal Number: 14200978
Properties and dynamics of the upper atmosphere of the hot- Neptune GJ 436b
PI Name: David Ehrenreich
Atmospheric escape of highly-irradiated exoplanets can be detected as strong absorption in the stellar Lyman-alpha line during planetary transits. The observed evaporation is thought to be driven by absorption of stellar X/EUV radiation. Here we propose to detect atmospheric escape from a hot-Neptune, GJ 436b. We demonstrated with HST/STIS that this star is a bright Lyman-alpha target. Hence, we will use this same instrument to measure the properties of the upper atmosphere of this hot-Neptune, constrain its escape rate, and search for temporal variations in its exosphere. We also propose coordinated Chandra observations of GJ 436bĘs transits to measure the atmospheric escape efficiency factor and test the impact of stellar X-ray variability on the atmospheric properties of the planet.
Subject Category: Hot Stars
Proposal Number: 14500977
Title: Multiwavelength spectra of the fine structure of the Crab
PI Name: Oleg Kargaltsev
Observations with HST and Chandra have resolved the remarkable dynamic PWN structure and advanced the theory of relativistic magnetized outflows in general and pulsar winds in particular. However, contemporaneous, multiwavelength spectra of the prominent PWN features are still lacking. We propose a joint HST-Chandra-EVLA campaign to understand multiwavelength spectral changes across the PWN. Thanks to the brightness of the Crab PWN and superb resolution of all the three observatories, spectral changes can be mapped on ~1 arcsecond scales in a very short time. This program is very efficient, highly synergistic, and will also provide a legacy set of contemporaneous, high-resolution images of the Crab PWN that will serve as a reference for years to come.
Subject Category: ISM and Circumstellar Matter
Proposal Number: 14910976
Title: Multiwavelength Spectroscopy of the Interstellar Medium: O and Ne Abundance ratio
PI Name: Yangsen Yao
The recent downward revision of several light elements has broken the accordance with helioseismological measurements. A much higher Ne/O abundance ratio may solve this problem, but this scenario has not been tested observationally. The interstellar medium (ISM) provides a natural laboratory for testing such a hypothesis. We propose a joint program by requesting COS-HST and LETG-Chandra observations of the low mass X-ray binary 4U 0512-401. The required observations will utilize the high resolving power of the COS to resolve the kinematic velocity components of the ISM absorbers, and then utilize LETG observations to measure column densities of OI, OII, NeI, NeII, NeIII, and HI. The results will enable us to examine whether the Ne/O ratio is substantially higher than that usually adopted.