8129( 4) - 05/10/99 09:22 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8129 Version: 4 Check-in Date: 10-May-1999 09:22:19 1.Proposal Title: Rapid UV Spectroscopy of Stellar Flares ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Richard Robinson Catholic University of America CoI: Dr. Kenneth Carpenter Goddard Space Flight Center N CoI: Dr. Bruce Woodgate Goddard Space Flight Center N ------------------------------------------------------------------------------------ 5. Abstract We propose to use STIS to obtain rapid time sequence spectra of stellar flares. The proposed observations will cover the wavelength range 2303-3111 Angstrom, which includes the expected peak of the continuum emission from the flare, numerous Fe II lines and the Mg II resonance lines, as well as the majority of the energy radiated in the UV/optical portion of the spectrum. This radiation is produced by the heating of the upper photosphere and/or chromosphere by energy propagating downward from the site of the original energy release in the lower corona. Groundbased photometry has shown that during the explosive phase of a stellar flare the continuum can change drastically on time scales of seconds or less. At present there is virtually no UV data with time resolutions capable of resolving these variations. With the proposed data we hope to study the variation of the continuum shape during the flare and thereby obtain some understanding of how and where the continuum is formed . Further, in conjunction with con temporaneous radio, optical and X-ray data, we hope to provide constraints on theoretical models of energy transport and flare dynamics. ------------------------------------------------------------------------------------ 8129( 4) - 05/10/99 09:22 - [ 2] Observations Description ------------------------ The proposed target for the observations is the M dwarf YZ CMi. This is a single star with a spectral type of dM4.5e, an apparent V magnitude of 11.2 and a distance from earth of 6 pc. It has been extensively studied for flares and is among the most active of all known flare stars, with an average flaring rate of 1.2 flares per hour for flares having a Johnson U band increase of 10\ more (Moffet, Ap.J. Supp, 29, 1, 1974). The star also generates a large number of energetic events, with nearly 30\ of 1 magnitude or more. We plan to observe the star using the E230M grating and the time-tag mode, so that a range of time resolutions can be examined. The IUE shows that the quiescent spectrum has a continuum flux of about 10^-14 erg cm^-2 s^-1 AA^-1 near 3000 A (Linsky et al, 1982). If we assume a flare with the same energy as that presented in Figure 2, then we expect a continuum intensity of ~ 3 * 10^-13 erg cm^-2 s^-1 AA^-1 near 2800 Angstrom\ (since YZ CMi is closer than AU M ic, which is at 10 pc). The peak o f the Mg II line would be ~ 1.5 * 10^-12 erg cm^-2 s^-1 AA^-1. Simulations show that the flare would have a count rate of 0.4 cnts s^-1 pix^-1 in the continuum and nearly 2 cnts s^-1 pix^-1 at the peak of the Mg II line. At 2800 Angstrom\ the resolution of the E230M grating is 0.045 Angstrom\ pix^- 1, so binning the data to 1 Angstrom\ resolution, which is acceptable for the continuum, gives a count rate of 9 cnts s^-1 bin^-1. This is suitable for examining rapid variability of the source. Integrating over the Mg II line gives an excess count rate (above the continuum) of more than 50 cnts s^-1. We propose to monitor the star for 6 HST orbits, which is the largest number of MAMA observations available in a single day. Given the flare rate for this star we expect about 6 detectable flares during this time, at least one of which has an energy comparable to the flare seen on AU Mic. It is hoped that the count rate from this large flare will be sufficient to study line profile va riations throughout the event. Real Time Justification ----------------------- We hope to coordinate with groundbased and satellite observations, as discussed in the scientific justification. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: Jennifer Sandoval, Code 681, Goddard Space Flight Center, Greenbelt, MD 20771 Ship Via: Email: stisdata@stis.gsfc.nasa.gov ------------------------------------------------------------------------------------ 8129( 4) - 05/10/99 09:22 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 YZCMI STAR, M V-IV, IRREGULAR RA=07H 44M 40.175S +/- 0.01S, J2000 V = 18 V = 11.2 VARIABLE, EMISSION LINE DEC=03D 33' 8.65" +/- 0.5" B-V = 1.59 STAR U-B = 1.00 TYPE=DM4.5E F-CONT(2400)=15+/-5e-14 F-CONT(2800)=20+/-5e-14 Comments: dM4.5e flare star Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 -0.023 -0.451 .169 8129( 4) - 05/10/99 09:22 - [ 4] Visit: 01 Visit Priority: Visit Requirements: BETWEEN 01-Jan-2000 AND 15-Feb-2000 SCHED 100% On Hold Comments: Additional Comments: We will attempt to coordinate these observations with groundbased and other satellite programs Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 YZCMI STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.2 S ONBOARD ACQ FOR 20, 30, CD P 40, 50, 60, 70 ------------------------------------------------------------------------------------------------------------------------------------ 20 YZCMI STIS/N TIME-TA 0.2X0.2 E230M 2707 BUFFER-TIME=5000 1 32 M UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 30 YZCMI STIS/N TIME-TA 0.2X0.2 E230M 2707 BUFFER-TIME=5000 1 40 M UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 40 YZCMI STIS/N TIME-TA 0.2X0.2 E230M 2707 BUFFER-TIME=5000 1 40 M UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 50 YZCMI STIS/N TIME-TA 0.2X0.2 E230M 2707 BUFFER-TIME=5000 1 40 M UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 60 YZCMI STIS/N TIME-TA 0.2X0.2 E230M 2707 BUFFER-TIME=5000 1 40 M UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 70 YZCMI STIS/N TIME-TA 0.2X0.2 E230M 2707 BUFFER-TIME=5000 1 40 M UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8129( 4) - 05/10/99 09:22 - [ 5] Summary Form for Proposal 8129 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 0.2X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT BUFFER-TIME=5000 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-Jan-2000 AND 15-Feb-2000 SCHED 100% ONBOARD ACQ FOR 20, 30, 40, 50, 60, 70 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E230M ------------------------------------------------------------------------------------------------------------------------------------ Target Names YZCMI ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 2707 ------------------------------------------------------------------------------------------------------------------------------------