Alert Notice 482: Monitoring requested for dust production study in developing planetary systems
April 4, 2013: Huan Meng and Dr. George Rieke (University of Arizona) have requested AAVSO assistance in monitoring three bright stars with developing planetary systems. The stars have been observed with NASA's Spitzer Space Telescope to have varying levels of dust in the circumstellar disk. These varying levels are thought to be produced through collisions among the asteroid-size debris in the disk. AAVSO monitoring is requested to make certain that the variations are not caused by variability in the stars themselves and for correlation with Spitzer data being obtained. For a more comprehensive explanation of the basis for this campaign, please see their article.
This campaign begins immediately and runs in two segments, now through May and September through December. The targets are BD+20 307, HD 15407A, and HD 23514; two are 9th magnitude in V and one is 7th in V. For each target the coordinates, basic photometry, desired time coverage, and comparison star information are given below.
Observations in V are requested, with a S/N of about 100 so that the accuracy will be 1-2%. The comparison stars have been chosen to be within the same field of view as the variable.
TARGET 1: BD+20 307
Coordinates: R.A. 01 54 50.34 Dec. +21 18 22.5 (J2000)
B = 9.5, V = 9.0, R = 8.7
Desired Time Coverage: 2013 ASAP - April 21; September 24 - November 17
Comparison star for BD+20 307: choice between two unnamed stars
12th magnitude unnamed star
Coordinates: R.A. 01 54 45.78 Dec. +21 16 55.1 (J2000)
V = 12.45
separation on the sky 1.8 arcmin
magnitude difference 3.4
or 10th magnitude unnamed star
Coordinates: R.A. 01 54 27.38 Dec. +21 10 46.7 (J2000)
V = 10.75
separation on the sky 9.3 arcmin
magnitude difference 1.75
TARGET 2: HD 15407A
Coordinates: R.A. 02 30 50.66 Dec. +55 32 54.2 (J2000)
B = 7.4, V = 7.0, R = 6.7
Desired Time Coverage: 2013 ASAP - May 14; October 14 - December 18
Comparison star for HD 15407A: HD 15407B
Coordinates: R.A. 02 30 48.6 Dec. +55 33 06.4 (J2000)
V = 9.60
separation on the sky 21 arcsec
magnitude difference 2.7
TARGET 3: HD 23514
Coordinates: R.A. 03 46 38.40 Dec. +22 55 11.2 (J2000)
B = 9.9, V = 9.5, R = 9.2
Desired Time Coverage: 2013 ASAP - May 17; October 21 - December 14
Comparison star for HD 23514 (BD+22 550): BD+22 552
Coordinates: R.A. 03 46 47.06 Dec. +22 54 52.43 (J2000)
V = 10.76
separation on the sky 2 arcmin
magnitude difference 1.3
Charts for these targets may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp).
Observations should be submitted to the AAVSO International Database using the names BD+20 307, HD 15407A, and HD 23514, respectively.
Regular observations of these stars during these intervals will be very important in analyzing the complex behavior of these systems. All contributions will be appreciated by the astronomers, and continuous monitoring especially so. The astronomers have indicated that observers who have done a significant amount of meaningful work would be co-authors of the resulting paper.
This campaign is being followed on the AAVSO Observing Campaigns page (http://www.aavso.org/observing-campaigns).
This AAVSO Alert Notice was compiled by Elizabeth Waagen.
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