Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/vscience/schedule/2013Spring/WolszczantagA2776.pdf Дата изменения: Tue Sep 11 04:14:24 2012 Дата индексирования: Tue Feb 5 00:31:28 2013 Кодировка: Поисковые слова: р р р р р р рер р

Proposal Identification No.:

A2776 Arecibo Observatory

Date Received: 2012-Sep-04 13:39:29 William E. Gordon Telescope Observing Time Request COVER SHEET

Section I - General Information
Submitted for Sep 1 2012. This proposal has not been submitted before. Proposal Type: General Category: Sub-Category: Observation Category: Time Requested this semester: Hours already used for this pro ject: Additional Hours required to complete pro ject: Minimum Useful Time: Expected Data Storage: Prop osal Title: ABSTRACT: Regular Astronomy Continuum Galactic 170

2 hours 100-500 GB

A continuation of the Arecibo survey of ultracool dwarfs

We have been interested in exploring the brown dwarf - massive planet boundary using magnetic fields as a diagnostic tool. A possibility to probe magnetic fields of the coolest, lowest-mass dwarfs may shed new light on the much debated transition from brown dwarfs to planets, the associated differences in structure, and the most proper way to distinguish between these two types of ob jects. In addition, magnetic field detections in the coolest dwarfs indicate that they may also be detectable in hot, young, but less massive exoplanets, which would have very interesting consequences for studies of planetary habitability. Encouraged by the results of our previous surveys (detection of flares from two ultracool dwarfs), we propose to continue this program using the Arecibo telescope with the S-band "high" and C-band receivers, and the Mock spectrometer to search for flares from a list of 40 recently discovered brown dwarf targets. Outreach Abstract: The high brightness temperature, highly polarized bursts from ultracool dwarfs at gigahertz frequencies are best explained by the coherent electron cyclotron maser emission from high plasma density regions at the presence of magnetic fields exceeding 1 kGauss. However, the mechanism (or mechanisms) by which a hot coronal plasma is generated in cool atmospheres of the L/T dwarfs are still to be identified. Similarly, it remains unclear, what sort of change of magnetic field generation occurs at the M7/M8 spectral type boundary, although the role of stellar rotation in this process appears to be clear enough. Our survey is designed to help addressing these problems. It also aims at using the magnetic field detection and measurements in the coolest dwarfs to find the best way to do the same with the hottest exoplanets. This may have important consequences for the studies of planetary habitability, as the presence of planetary magnetic fields is needed to protect life from stellar winds.

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Name Alexander Wolszczan Matthew Route

Institution Penn State University Penn State University

E-mail alex@astro.psu.edu mroute@astro.psu.edu

Phone 814 863 1756 814 865 0418

Student no G

This work is part of a PhD thesis.

Remote Observing Request

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

Section I I - Time Request
The following times are in LST. For these observations night-time is required.

Begin ­ End Interval­Interval 6:00 ­ 14:00 21:00 ­ 2:00 ­ ­

Days Needed at This Interval 16 10

Time Constraints (Must Be Justified in the Prop osal Text) Because of the weather and radio interference concerns, we request the observing time to be allocated at night and in the winter/early spring months. The RAs of our targets have been selected to fall in the LST ranges that are crowded by the observing time requests. We need two hour observing runs per target at each frequency. The DECs of the targets are within appropriate limits to achieve this. The above numbers of day estimates are based on 6 hour time allocations per day and are flexible.

Section I I I - Instruments Needed
C S-high

Atmospheric Observation Instruments: 2


Sp ecial Equipment or setup:

none

Section IV - RFI Considerations Frequency Ranges Planned

Section V - Observing List Target List
See the additional page of the proposal.

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