Now showing items 1-13 of 13

• #### An ALMA Survey of DCN/H13CN and DCO+/H13CO+in Protoplanetary Disks ﻿

(American Astronomical Society, 2017-01-31)
The deuterium enrichment of molecules is sensitive to their formation environment. Constraining patterns of deuterium chemistry in protoplanetary disks is therefore useful for probing how material is inherited or reprocessed ...
• #### Applications of High-Resolution Observations of Millimeter Wavelengths ﻿

(2015-12-17)
nterferometric observations at millimeter wavelengths provide a precious, detailed view of certain astrophysical objects. This thesis is composed of studies that both rely on and enable this technique to study the structure ...
• #### Chemical Imaging of the CO Snow Line in the HD 163296 Disk ﻿

(IOP Publishing, 2015)
The condensation fronts (snow lines) of H2O, CO, and other abundant volatiles in the midplane of a protoplanetary disk affect several aspects of planet formation. Locating the CO snow line, where the CO gas column density ...
• #### The comet-like composition of a protoplanetary disk as revealed by complex cyanides ﻿

(Nature Publishing Group, 2015)
Observations of comets and asteroids show that the Solar Nebula that spawned our planetary system was rich in water and organic molecules. Bombardment brought these organics to the young Earth's surface, seeding its early ...
• #### The distribution and chemistry of H2CO in the DM Tau protoplanetary disk ﻿

(IOP Publishing, 2015)
H2CO ice on dust grains is an important precursor of complex organic molecules (COMs). H2CO gas can be readily observed in protoplanetary disks and may be used to trace COM chemistry. However, its utility as a COM probe ...
• #### Double DCO+ rings reveal CO ice desorption in the outer disk around IM Lup ﻿

(IOP Publishing, 2015)
In a protoplanetary disk, a combination of thermal and non-thermal desorption processes regulate where volatiles are liberated from icy grain mantles into the gas phase. Non-thermal desorption should result in volatile-enriched ...
• #### The Fundamental Properties of Young Stars ﻿

(2016-05-18)
Accurate knowledge of the fundamental properties of stars--mass, temperature, and luminosity--is key to our understanding of stellar evolution. In particular, empirical measurements of stellar mass are difficult to make ...
• #### H2CO Distribution and Formation in the TW HYA Disk ﻿

(American Astronomical Society, 2017-04-12)
H2CO is one of the most readily detected organic molecules in protoplanetary disks. Yet its distribution and dominant formation pathway(s) remain largely unconstrained. To address these issues, we present ALMA observations ...
• #### Imaging of the CO Snow Line in a Solar Nebula Analog ﻿

(American Association for the Advancement of Science (AAAS), 2013)
Planets form in the disks around young stars. Their formation efficiency and composition are intimately linked to the protoplanetary disk locations of “snow lines” of abundant volatiles. We present chemical imaging of the ...
• #### A Multi-Ringed, Modestly Inclined Protoplanetary Disk Around AA Tau ﻿

(American Astronomical Society, 2017-05-02)
AA Tau is the archetype for a class of stars with a peculiar periodic photometric variability thought to be related to a warped inner disk structure with a nearly edge-on viewing geometry. We present high resolution ...
• #### An Old Disk Still Capable of Forming a Planetary System ﻿

(Nature Publishing Group, 2013)
From the masses of the planets orbiting the Sun, and the abundance of elements relative to hydrogen, it is estimated that when the Solar System formed, the circumstellar disk must have had a minimum mass of around 0.01 ...
• #### Protoplanetary Disks in Multiple Star Systems ﻿

(2013-10-18)
Most stars are born in multiple systems, so the presence of a stellar companion may commonly influence planet formation. Theory indicates that companions may inhibit planet formation in two ways. First, dynamical ...
• #### Variable H13CO+ Emission in the IM Lup Disk: X-Ray Driven Time-dependent Chemistry? ﻿

(American Astronomical Society, 2017-06-23)
We report the first detection of a substantial brightening event in an isotopologue of a key molecular ion, HCO+, within a protoplanetary disk of a T Tauri star. The H13CO+ $J=3-2$ rotational transition was observed three ...