13432( 4) - 27-Jun-2013 14:46:42 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13432 Version: 4 Check-in Time: 27-Jun-2013 14:46:42 STScI Edit Number: 0 Title To be or not to be the progenitor: The question about Tycho-B ------------------------------------------------------------------------------------ Type Cycle GO 21 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Wolfgang E Kerzendorf University of Toronto Y CoI: Dr. Knox S. Long Space Telescope Science Institute N CoI: Dr. P. Frank Winkler Middlebury College N CoI: Dr. Marten H. van Kerkwijk University of Toronto N CoI: Prof. Kim A. Venn University of Victoria N ------------------------------------------------------------------------------------ Abstract Despite the importance of Type Ia SNe, we still do not know whether they result from mass transfer onto a WD from a non-degenerate companion, from the coalescence of two degenerate stars, or perhaps a from a combination of these two pathways. Here we seek to show, by identifying the donor star, that SN1572--the prototypical Galactic SN Ia reported by Tycho--resulted from the single-degenerate scenario. We know from ground-based high-resolution spectra that many stars near the projected center of SN1572 lack the characteristics expected for a donor companion. But one of them, the unusual A-star denoted Tycho-B, exhibits fast rotation and an unusual abundance pattern of low overall metallicity ([Fe/H]~-1) yet high abundances of C and O. Tycho-B is a few arcsec from the geometric center of SN1572, and our distance estimate is consistent with that for SN1572. If Tycho-B is in fact the surviving companion, it must be located within the SNR shell. In this case, we expect it will show broad, blue-shifted absorption in Fe II from undecelerated cold ejecta that have long-since swept past the companion star, but have not yet encountered a reverse shock. We propose to use HST/STIS to obtain UV spectra that will clearly reveal such absorption. While a positive result is not guaranteed, the potential payoff of establishing Tycho-B as the donor is large. If Tycho-B is instead a background object, these spectra will still provide an important probe for the cold ejecta in SN1572, as we have done for the older Ia remnant of SN1006. ------------------------------------------------------------------------------------ Observations Description ------------------------ We are aiming to acquire a STIS NUV spectrum of the the star Tycho-B (U=16.78). Tycho-B is located roughly 3 arcseconds from Tycho-A (U=15.96), which we will use as a acquisition and "guide" star. We want to have the slit over both these stars so we know about the contamination of Tycho-B from Tycho-A. We plan to acquire once and then spent our two orbits observing. Real Time Justification ----------------------- Calibration Justification ------------------------- 13432( 4) - 27-Jun-2013 14:46:42 - [ 2] Additional Comments ------------------- ------------------------------------------------------------------------------------ 13432( 4) - 27-Jun-2013 14:46:42 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 RCM2004-TYCH STAR, A0-A3 V-IV RA=00H25M20.0406S +/- 0.1", J2000 V = -45 V = 15.4 +/- 0.03 B=16.35, U=16.78 O-B DEC=+64D08'17.37" +/- 0.1" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 2 RCM2004-TYCH STAR, F0-F2 RA=00H25M19.8082S, J2000 V = 13.3 U=15.96 O-A DEC=+64D08'19.99" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 13432( 4) - 27-Jun-2013 14:46:42 - [ 4] Visit: 01 Visit Requirements: ORIENT 15D TO 15 D; ORIENT 195D TO 195 D 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 RCM2004-TYC STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=POINT 1 1 S (1 S) HO-A ------------------------------------------------------------------------------------------------------------------------------------ 2 RCM2004-TYC STIS/NUV ACCUM 52X0.5 G230L 2376 2 1860 S HO-B -MAMA see below (5868 S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ RCM2004-TYCHO-A 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A RCM2004-TYCHO-B 2 STIS/NUV ACCUM 52X0.5 G230L 2376 none none 1 none 1 2630.0 S -MAMA RCM2004-TYCHO-B 2 STIS/NUV ACCUM 52X0.5 G230L 2376 none none 2 none 2 3238.0 S -MAMA 13432( 4) - 27-Jun-2013 14:46:42 - [ 5] Summary Form for Proposal 13432 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.5, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 15D TO 15 D, ORIENT 195D TO 195 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G230L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names RCM2004-TYCHO-A, RCM2004-TYCHO-B ------------------------------------------------------------------------------------------------------------------------------------