Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/vscience/schedule/tpfiles/BaniatagA2351tp.pdf Дата изменения: Thu Nov 17 22:10:42 2011 Дата индексирования: Mon Feb 4 19:24:51 2013 Кодировка: Поисковые слова: ceres

Proposal Identification No.:

A2351

Date Received: 2007 -Oct-05 16:37:05

Technical Page
Proposal Type: General Category: Sub-Category: Observation Category: Total Time Requested: Minimum Useful Time: Prop osal Title: ABSTRACT: Regular Astronomy Spectroscopy Galactic 84 Hours full sideral pass is the minimum

Stalking the Cosmic 3-Helium Abundance

Our measurements of 3-He in the Galaxy have led to "The 3-He Problem" whereby HII region abundances do not show the 3-He enrichment expected from standard stellar nucleosynthesis yet some planetary nebulae (PNe) have 3-He abundances that are in accord with standard models. Recently Eggleton et al. used a new 3D hydrodynamic code to model a low-mass star at the tip of the red giant branch. They claim to have discovered an instability that leads to extra-mixing and a concomitant destruction of 3-He. They claim this is a Raleigh-Taylor instability caused by a molecular weight inversion that is produced by 3-He burning at the edge of the hydrogen burning shell. This scenario predicts that ALL stars should experience this instability and destroy the 3-He produced during main sequence evolution. This is inconsistent with our detections of 3-He at canonical abundances in NGC3242 and J320. We will use the unique spectral sensitivity of the Arecibo telescope to confirm our J320 detection and to improve the tentative detections we have for 2 more PNe. Robust 3-He PNe detections at canonical abundances will falsify the universality of the Eggleton et al. mixing hypothesis.

Name Thomas M Bania

Institution Boston University

E-mail bania@bu.edu

Phone 617.353.3652

Student no

Remote Observing Request

X

Observer will travel to AO Remote Observing In Absentia (instructions to operator)

Instrument Setup
X-high Atmospheric Observation Instruments:

1


Sp ecial Equipment or setup:

none

RFI Considerations Frequency Ranges Planned
8 - 10 GHz experience shows RFI at relevant bands is not an issue.

2