Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/vscience/schedule/2014Spring/WolszczantagA2856.pdf Дата изменения: Fri Sep 6 19:44:21 2013 Дата индексирования: Sat Mar 1 02:28:43 2014 Кодировка:

Proposal Identification No.:

A2856 Arecibo Observatory

Date Received: 2013-Aug-23 12:02:18 William E. Gordon Telescope Observing Time Request COVER SHEET

Section I - General Information
Submitted for Sep 1 2013. 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: We have recently used the Arecibo telescope and the Mock spectrometer to make timing measurements of an ultracool dwarf (UCD), TVLM 513-46546, at 5 GHz. The astonishing result of these measurements was that the 1.96 hour period of radio flares from this ob ject had been systematically decreasing over 6 months in 2012/2013 at the average rate of 10 ms/day. A plausible explanation of this effect is that it is caused by a differential rotation of the dwarf, combined with the migration of radio active regions toward the equator, in a manner similar to the behavior of sunspots that create the famous "butterfly" diagram for the Sun. If true, this would be the first detection of a differential rotation of an UCD, and a demonstration of the usefulness of flare timing as a tool to better understand the internal structure of these ob jects. We propose to observe TVLM 513 and two other similar UCDs to verify the above idea and to explore any alternative interpretations of our observations. Outreach Abstract: Stars do not rotate as rigid bodies. This effect is easiest to observe by measuring the rotation of spots on the Sun, which do so once every 25 days close to the solar equator, but slow down at higher altitudes. This effect, called the differential rotation, and the migration of spots toward the equator during the solar cycle, create the famous "butterfly" pattern that plays an important role in our efforts to better understand the workings of the solar interior and their effect on solar activity. Not surprisingly, differential rotation has been detected in other stars. However, nothing is known about it in the case of brown dwarfs, the very dim, Jupiter-sized ob jects, which are not massive enough to shine like stars. We propose to use the Arecibo radio telescope to observe radio flares from three brown dwarfs and use measurements of flare arrival times to detect their differential rotation. Regular Astronomy Continuum Galactic 100 0 2 hours less than 100 GB

Timing the periodically flaring ultracool dwarfs, TVLM 513-46546, 2M J0746+2000, and LSR 1835+3259

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Name Alexander Wolszczan Gabriel Ortiz Pena

Institution Penn State University Penn State University

E-mail alex@astro.psu.edu gho5001@psu.edu

Phone 814 863 1756 814 865 0418

Student no U

This work is not part of a 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 06:40 ­ 08:40 14:00 ­ 16:00 17:30 ­ 19:30 ­

Days Needed at This Interval 26 42 26

Time Constraints (Must Be Justified in the Prop osal Text) Observations should be restricted to nighttime, to minimize the RFI and avoid the solar radiation. The exact observing patterns for the three targets, as specified in the science part of the proposal, are dictated by the logic of the development of timing models for periodically emitting sources (high cadence observations initially, followed by gradually less frequent measurements). Two- hour runs are needed to maximize chances of actually observing a flare, given the flaring periods of the sources (1.96, 2.07, 2.84 hours).

Section I I I - Instruments Needed
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Atmospheric Observation Instruments:

Sp ecial Equipment or setup:

none

Section IV - RFI Considerations Frequency Ranges Planned
4200 - 5100

Section V - Observing List Target List
07:46:43 20 00 32 15:01:08 22:50:02 18:35:38 32:59:55

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