11716( 3) - 01-Jul-2009 14:48:35 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 11716 Version: 3 Check-in Time: 01-Jul-2009 14:48:35 STScI Edit Number: 0 Title In Search of the Lost Remnant of M31 RV: Shedding Light on the New Class of Luminous Red Transients ------------------------------------------------------------------------------------ Type Cycle GO 17 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Howard E. Bond Space Telescope Science Institute ------------------------------------------------------------------------------------ Abstract M31 RV is a luminous red variable star that appeared in the bulge of M31 in 1988. During its outburst, which lasted a few months, it was one of the brightest stars in the Local Group. Unlike a classical nova, it was extremely cool during the eruption, and it never became optically thin or exposed a hot, blue source. There has been renewed interest in M31 RV recently, because of its remarkable similarities to V838 Mon, a luminous Galactic variable star that underwent a similar rapid expansion to become a red supergiant, and which is currently illuminating a spectacular light echo, extensively observed by HST. The outburst mechanism for this new class of luminous transients remains unknown, and is one of the major current challenges to our understanding of stellar physics. Bond and Siegel have examined WFPC2 frames of the site of M31 RV, obtained fortuitously in 1999 as parallel observations during spectroscopic studies of the nucleus of M31. The explosion site shows only a pure old population of red giants, with no obvious remnant of M31 RV. I propose now to obtain second-epoch images of the site, in the same filters, to determine whether there is an object in the field that has faded or varied, and if so what its brightness and color is. This information may provide new constraints on proposed outburst mechanisms, such as stellar mergers or collisions, and could lead to a spectroscopic observation in a future HST cycle. ------------------------------------------------------------------------------------ Observations Description ------------------------ Previous description: I will obtain ACS/HRC images of the site of M31 RV in F555W and F814W. A three-point dither pattern will be used, with exposures of 450 sec in V and 300 sec in I at each of the 3 points. June 2009 revision: Since ACS/HRC was not repaired in AM4, I am changing to WFC3/UVIS. A three-point dither will be used, with exposures of 565 sec in V and 325 sec in I at each of the 3 points. I am greatly increasing the total exposure time possible during the single orbit by using the UVIS1-M512-SUB subarray. Real Time Justification ----------------------- Calibration Justification 11716( 3) - 01-Jul-2009 14:48:35 - [ 2] ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 11716( 3) - 01-Jul-2009 14:48:35 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-RV EXT-STAR, BULGE, M RA=00H43M2.4330S +/- 0.1", J2000 V = 22 III-I DEC=+41D12'56.17" +/- 0.1" Reference Frame: ICRS Comments: ------------------------------------------------------------------------------------------------------------------------------------ 11716( 3) - 01-Jul-2009 14:48:35 - [ 4] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-RV WFC3/UVI ACCUM UVIS1-M51 F555W CR-SPLIT=NO 1 565 S POS TARG -0.0924, S 2-SUB see below -0.0917 ------------------------------------------------------------------------------------------------------------------------------------ 2 M31-RV WFC3/UVI ACCUM UVIS1-M51 F814W CR-SPLIT=NO 1 325 S POS TARG -0.0924, S 2-SUB see below -0.0917 ------------------------------------------------------------------------------------------------------------------------------------ 3 M31-RV WFC3/UVI ACCUM UVIS1-M51 F814W CR-SPLIT=NO 1 325 S POS TARG 0, 0 S 2-SUB see below ------------------------------------------------------------------------------------------------------------------------------------ 4 M31-RV WFC3/UVI ACCUM UVIS1-M51 F555W CR-SPLIT=NO 1 565 S POS TARG 0, 0 S 2-SUB see below ------------------------------------------------------------------------------------------------------------------------------------ 5 M31-RV WFC3/UVI ACCUM UVIS1-M51 F555W CR-SPLIT=NO 1 565 S POS TARG 0.0924, 0.0917 S 2-SUB see below ------------------------------------------------------------------------------------------------------------------------------------ 6 M31-RV WFC3/UVI ACCUM UVIS1-M51 F814W CR-SPLIT=NO 1 325 S POS TARG 0.0924, 0.0917 S 2-SUB see below ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ M31-RV 1 WFC3/UVI ACCUM UVIS1-M5 F555W none none none none 1 569.0 S S 12-SUB M31-RV 2 WFC3/UVI ACCUM UVIS1-M5 F814W none none none none 1 329.0 S S 12-SUB M31-RV 3 WFC3/UVI ACCUM UVIS1-M5 F814W none none none none 1 329.0 S S 12-SUB M31-RV 4 WFC3/UVI ACCUM UVIS1-M5 F555W none none none none 1 569.0 S S 12-SUB M31-RV 5 WFC3/UVI ACCUM UVIS1-M5 F555W none none none none 1 569.0 S S 12-SUB M31-RV 6 WFC3/UVI ACCUM UVIS1-M5 F814W none none none none 1 329.0 S S 12-SUB 11716( 3) - 01-Jul-2009 14:48:35 - [ 5] Summary Form for Proposal 11716 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS1-M512-SUB ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements POS TARG -0.0924, -0.0917, POS TARG 0, 0, POS TARG 0.0924, 0.0917 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names M31-RV ------------------------------------------------------------------------------------------------------------------------------------