Campaign continued through 2017 at least. Also, campaign updated in AAVSO Special Notice #408 (20151002).
March 13, 2015: Dr. George Rieke (University of Arizona) and colleagues have requested AAVSO assistance in monitoring four stars with developing planetary systems. The targets are RZ Psc, HD 15407A, V488 Per, and HD 23514. This campaign is similar to the one conducted in 2013 (see AAVSO Alert Notice 482).
Dr. Rieke writes: "We have obtained 130 hours of time on the Spitzer Space Telescope to continue monitoring planetary debris disks for variability. We are asking for help from AAVSO for this program.
"Debris disks - systems of dust and particles associated with planetary systems - are most easily observed from the infrared emission of their dust when it is warmed by the star, although a small number have also been observed in scattered emission, mostly by HST. They are a powerful approach to understanding planetary systems and their evolution because they can be detected at all phases of the development of a planetary system, and to large distances. Hundreds of them are known from IRAS, ISO, Spitzer, WISE, and Herschel. Among these hundreds, there are about a dozen where there is evidence that massive collisions are occurring right now, collisions that are building planets in much the same way that a large body added most of its mass to that of the Earth and created the Moon as a byproduct when the Solar System was young... A paper from Science describing the most thoroughly studied such system [may be found here]. A second paper on a larger number of variable debris disks has been submitted and we have received the referee report; the necessary revisions will be complete soon for final publication.
"A key part of our program is to obtain optical photometry of the same stars that we are observing in the infrared under the Spitzer program. The optical data are needed to verify that any changes we see in the infrared are not just driven by changes in the brightness of the star, but are truly due to changes in the structure or dust content of the debris disk. AAVSO observers provided this support for our previous program, as summarized in the paper about to go back to the journal after refereeing; all of those who contributed data are co-authors of the paper.
"We request AAVSO to take similar observations for the new program. The table below lists the stars we are observing and basic information about them, and the two visibility windows for Spitzer (all observations will be obtained within the range of dates indicated)."
This campaign begins immediately and runs in two segments, now through May and September through December.
Target
|
SpT
|
Age
(Myr)
|
Vmag
|
R.A. (2000)
|
Dec. (2000)
|
Sptizer visibility
First segment
|
Sptizer visibility
Second segment
|
|---|---|---|---|---|---|---|---|
| RZ Psc | KOIV | 35 | 11.29 | 01 09 42.06 | +27 57 01.95 | Mar 14-Apr 24 | Oct 10-Nov 20 |
| HD 15407A | F5V | 80 | 6.95 | 02 30 50.66 | +55 32 54.2 | Apr 5-May 24 | Nov 7-Dec 28 |
| V488 Per | KOIV | 60 | 12.83 | 03 28 18.68 | +48 39 48.2 | Apr 17-May 30 | Nov 15-Dec 31 |
| HD 23514 | F5V | 150 | 9.43 | 03 46 38.40 | +22 55 11.2 | Apr 18-May 26 | Nov 13-Dec 23 |
Dr. Rieke and we recognize that all of these targets will be very near conjunction between now and the end of May, and so may be extremely difficult if not impossible to observe from the ground until nearly the end of the first segment. However, they are all observable with Spitzer during the first segment because of its orbit. Any morning observations that you are able to make will be greatly appreciated! During the second segment, the stars will be much better placed for observations from the ground; these observations will also be greatly appreciated. We will issue an AAVSO Special Notice to remind observers before the second segment begins.
Observations in V are requested, with a S/N of about 100 so that the accuracy will be 1-2%. Observations should begin at least one week before the visibility window opens and finish one week after the window closes.
No specific comparison stars are assigned for each target, but observers are requested to use only those in the sequences available via the AAVSO Variable Star Plotter (VSP). It is essential that observers report the comparison stars used when submitting their observations to the AAVSO.
Observations should be submitted to the AAVSO International Database using the names RZ PSC, HD 15407A, HD 23514, and V488 PER, respectively.
This campaign is being followed on the AAVSO Observing Campaigns page.
This AAVSO Alert Notice was compiled by Elizabeth Waagen.
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