9415( 2) - 01/24/02 09:51 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9415 Version: 2 Check-in Date: 24-Jan-2002 09:51:16 1.Proposal Title: Is the Compact HVC Toward Ton S210 Remnant Debris from the Formation of the Local Group? ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Kenneth Sembach Space Telescope Science Institute CoI: Dr. Brad Gibson Swinburne University of Technology N CoI: Dr. Christopher Howk The Johns Hopkins University N CoI: Dr. Blair Savage University of Wisconsin-Madison N CoI: Dr. Mary Putman University of Colorado N ------------------------------------------------------------------------------------ 5. Abstract There is a fortuitous coincidence in the positions of the quasar Ton S210 and a compact ionH1 high velocity cloud on the sky that makes it possible to test the hypothesis that such clouds are extragalactic entities located in the Local Group. The HVC toward Ton S210 has H I 21 cm emission properties similar to those of isolated compact HVCs suspected of being Local Group clouds. It has recently been detected in O VI absorption by FUSE, which suggests that either there is hot gas associated with the collapse of the cloud or that the HVC is interacting with a hot, tenuous Galactic halo or Local Group medium. We propose to observe the HVC in absorption against the smooth ultraviolet continuum of Ton S210 with HST/STIS. To answer the question posed in the proposal title, we will combine the STIS observation with extant FUSE and H I 21 cm data to determine the metallicity, elemental abundances, and ionization properties of the HVC. To date, such information has been difficult to obtain for all but a few HVCs, and this is the first time such an opportunity has been available for a compact HVC. The results of this study will bear directly upon the issues of the locations of compact HVCs, the ionization conditions of HVCs detected in O VI absorption, and the possible influence HVCs might have on the chemical evolution of galaxies. ------------------------------------------------------------------------------------ 9415( 2) - 01/24/02 09:51 - [ 2] Observations Description ------------------------ Our proposed STIS observations are designed to study the metallicity, elemental abundances, and ionization of the compact high velocity cloud toward Ton S210. We will use the intermediate-resolution STIS echelle gratings (E140M and E230M) to observe neutral and ionized gas species in the 1150-1735A and 2011-2819A spectral regions. Neutral and weakly ionized gas tracers covered include H I LyAlpha, C II 1334; C II* 1335; the N I 1200 triplet; O I 1302, Mg II 2796, 2803; Al II 1670; Si II 1190, 1260, 1304, 1526; S II 1250, 1253, 1259; and Fe II 1608, 2343, 2374, 2382, 2585, 2600. Additional weak lines of C I, Mg I, Mg II, Cr II, Mg II, Fe II, Ni II, and Zn II are also covered by these integrations. The primary diagnostics of ionized gas in these wavelength ranges include C IV 1548, 1550; N V 1238, 1242; Si III 1206; Si IV 1393, 1402; and S III 1190. We will obtain the observations through the 0.2"*0.06" aperture to maintain the high spectral resolution (E140M: ~7 km/s; E230M: ~10 km/s) required to determine accurate column densities and line widths in the HVC gas. Ton S210 has not been observed with HST. Real Time Justification ----------------------- None. None necessary. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9415( 2) - 01/24/02 09:51 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 TONS210 GALAXY, QSO RA=01H 21M 51.52S +/- 0.4", DEC= J2000 Z = F(1250)=4.0+/-0.2e-14 -28D 20' 57.6" +/- 0.4", PLATE- 0.116 F(1400)=4.0+/-0.2e-14 ID=00DA V = 14.7+/-0.3 Coordinate Source: GUIDE_STAR_CATALOG 9415( 2) - 01/24/02 09:51 - [ 4] Visit: 01 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 TONS210 STIS/C ACQ F28X50L MIRROR 1 3.0 S CD P Comments: Expect a peak of about 5000 e- in brightest pixel. Expected S/N ~ 90. Target acquisition ETC used with QSO energy distribution and F(1400)=4E-14 and z = 0.116. ------------------------------------------------------------------------------------------------------------------------------------ 20 TONS210 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 3.0 S CD K 6 Comments: Expect about 37, 000 counts total for clear filter, so expect about 50% of that for 0.2x0.06 slit. So this should work fine. Other input parameters same as above. ------------------------------------------------------------------------------------------------------------------------------------ 30 TONS210 STIS/F ACCUM 0.2X0.0 E140M 1425 1 2000 S UV-MAM 6 A Comments: Far-UV MAMA exposure covers 1150-1700 A at ~7 km/s res. ------------------------------------------------------------------------------------------------------------------------------------ 40 TONS210 STIS/F ACCUM 0.2X0.0 E140M 1425 4 3000 S UV-MAM 6 A Comments: Far-UV MAMA exposure covers 1150-1700 A at ~7 km/s res. ------------------------------------------------------------------------------------------------------------------------------------ 9415( 2) - 01/24/02 09:51 - [ 5] Visit: 02 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 TONS210 STIS/C ACQ F28X50L MIRROR 1 3.0 S CD P Comments: Expect a peak of about 5000 e- in brightest pixel. Expected S/N ~ 90. Target acquisition ETC used with QSO energy distribution and F(1400)=4E-14 and z = 0.116. ------------------------------------------------------------------------------------------------------------------------------------ 20 TONS210 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 3.0 S CD K 6 Comments: Expect about 37, 000 counts total for clear filter, so expect about 50% of that for 0.2x0.06 slit. So this should work fine. Other input parameters same as above. ------------------------------------------------------------------------------------------------------------------------------------ 30 TONS210 STIS/N ACCUM 0.2X0.0 E230M 2415 1 2000 S UV-MAM 6 A Comments: Near-UV MAMA exposure covers 1150-1700 A at ~10 km/s res. ------------------------------------------------------------------------------------------------------------------------------------ 41 TONS210 STIS/N ACCUM 0.2X0.0 E230M 2415 1 3000 S UV-MAM 6 A Comments: Near-UV MAMA exposure covers 1150-1700 A at ~10 km/s res. ------------------------------------------------------------------------------------------------------------------------------------ 50 TONS210 STIS/F ACCUM 0.2X0.0 E140M 1425 3 3000 S UV-MAM 6 A Comments: Far-UV MAMA exposure covers 1150-1700 A at ~7 km/s res. ------------------------------------------------------------------------------------------------------------------------------------ 9415( 2) - 01/24/02 09:51 - [ 6] Summary Form for Proposal 9415 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 0.2X0.06 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140M E230M ------------------------------------------------------------------------------------------------------------------------------------ Target Names TONS210 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 2415 ------------------------------------------------------------------------------------------------------------------------------------