Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Keyword
Articles 1 - 4 of 4
Full-Text Articles in Astrophysics and Astronomy
Analysis Of The Primary Volatile Compositions In The Oort Cloud And Jupiter-Family Comets Towards The Goal Of Understanding Their Origin And Diversity, Mohammad Saki
Doctoral Dissertations
“Knowledge of the initial conditions present in the early solar nebula is required to understand the evolution and its current volatile content. Comets were some of the first objects to accrete in the solar nebula. They are among the most pristine (primitive) remnants of the solar system formation, and their present-day volatile composition likely reflects the composition and conditions where (and when) they formed. Therefore, they are fossils of the solar system formation. High-resolution near-infrared spectroscopy is a valuable tool for sampling the parent volatile (i.e., ices subliming directly from the nucleus) composition of comets via analysis of fluorescence emission …
A Spectroscopic And Photometric Survey Of The W4 Hii Region And Its Young Stellar Population, Matt Wentzel-Long
A Spectroscopic And Photometric Survey Of The W4 Hii Region And Its Young Stellar Population, Matt Wentzel-Long
Doctoral Dissertations
”The W4 HII region is home to a large number of O and B-type stars as well as the young open cluster IC 1805. OB-type produce intense photoionizing radiation and stellar winds that can induce star formation in surrounding molecular clouds and sometimes carve out large regions of decreased particle density called superbubbles. During the star- formation process, young stellar objects (YSOs) are initially surrounded by circumstellar disks made of gas and dust which naturally dissipate after several million years. The dissipation of the disk is thought to occur for a variety of reasons, including photoevaporation by the encompassed protostar …
The Dynamical State Of A Young Stellar Cluster, Timothy Sullivan
The Dynamical State Of A Young Stellar Cluster, Timothy Sullivan
Doctoral Dissertations
"The dynamical state of the young star-forming cluster Rho Ophiuchi is considered, with emphasis on the L1688 cloud. Radial velocities are derived for 32 YSOs, with some being multi-epoch, using Markov-Chain Monte Carlo routines based upon the package emcee. Sources are chosen based upon their spectral index to focus on the earlier stages of star formation, in this case, Class I and Flat spectrum objects, and compared with a sample of Class II and III objects from the same embedded cluster. It is found that the radial velocity dispersion for these younger objects is Δv = 2.8 ± 0:6 …
Spectroscopic And Spectro-Astrometric Analysis Of T Tauri Stars, Logan Ryan Brown
Spectroscopic And Spectro-Astrometric Analysis Of T Tauri Stars, Logan Ryan Brown
Doctoral Dissertations
"To understand our own solar origins, we must investigate the composition of the protoplanetary disk from which the solar system formed. To infer this, we study analogs to the early solar system called T Tauri stars. These objects are low-mass, pre-main sequence stars surrounded by circumstellar disks of material from which planets are believed to form. We present high-resolution, near-infrared spectroscopic data for the T Tauri stars DR Tau and AA Tau using NIRSPEC at the Keck II telescope. For DR Tau, a spectro-astrometric analysis was performed, obtaining sub-seeing spatial information on water emission. Alongside a disk model, we constrained …