Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5487 Report Date: 18-Jul-95:17:31 Version: ********** Check-in Date: ********** 1.Proposal Title: CHEMICAL AND PHYSICAL PROCESSES IN DENSE IS CLOUDS CYCLE4MEDIUM ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID INTERSTELLAR MEDIUM GO Sub Category ABSORPTION LINES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Theodore P. Snow 1762 USA (303) 492-4050 ------------------------------------------------------------------------------------ 7. Abstract We propose to continue a study of translucent clouds that was begun during Cycle 1, by observing several atomic and molecule transitions in the spectrum of HD24534 (X Persei). Existing data demonstrate that this line of sight has extremely high molecular column densities (e.g. N(H2) in excess of 10(21) cm-2) and low far-UV extinction (in strong contrast with other well-studied sightlines in the Perseus cloud complex). The high column densities, combined with the high UV flux levels, resulting from the low extinction, make X Per perhaps the best candidate of all for HST detections of new molecular species. Very high S/N can be obtained in reasonably short exposure times. We propose to observe 19 wavelength settings using the echelle modes of the GHRS, obtaining S/N levels ranging from 30 to 300, in a total of 15.85 hours exposure time. The results of this study will: (1) provide perhaps the most complete picture yet of chemical and physical processes in translucent clouds; and (2) provide a complementary case study for our ongoing studies of other clouds (one in Perseus) having steep far-UV extinction, hence contrasting UV radiation environments. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 20.00 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5487 PI: Theodore P. Snow Proposal Title: CHEMICAL AND PHYSICAL PROCESSES IN DENSE IS CLOUDS CYCLE4MEDIUM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Theodore P Snow 1762 USA John H Black 1210 USA Richard M Crutcher 2250 USA Barry L Lutz 3000 USA Ewine F Van Dishoeck 6870 NETHERLANDS X ------------------------------------------------------------------------------------ 3. Description of proposed observations. Table 1. Grating settings. ============================================================= Wavelength Grating Species ------------------------------------------------------------- 1240.3 Ech -A* H2O, Mg II, S I, N V 1262.0 C I, Si II, S I, S II, Fe II, CO 1279.2 H2*, C I, CO, P I, S I* 1288.2 HCl, CO, P I, P II*, Ti III, H2* 1304.2 O I, Si II, P II, S I, CO, 13CO 1335.5 C II, S I], Cl I, H2* 1342.0 C2 1358.9 O I], B II, Cu II, H2*, Zn I 1370.5 CH, CO, 13CO, P I, Cl I, Ni II, Cu II 1414.0 CH2, S I, S I**, Ni II, Ni II*, H2*, Ga II 1706.4 Mg I, Mg I], Si I*, Ni II, Cu I, Ge I 1806.7 Ech-B Si II, S I, Ni II, Ge I, As I, O2 2026.0 Zn II, Co II, Mg I 2299.0 SiO 2313.0 C2 2326.0 C II], Ni I 2369.0 Fe II, Cr I, Co I, Al I, Mn I 2582.0 Fe II, CS, SO, Mn II 3078.0 OH, Ti II, Al I *Ech-A provides superior data quality for these short- wavelength settings, but very useful information can be derived from G160M spectra, as we have found from analysis of our Cycle 1 data on HD 154368; hence we expect to petition for G160M observations to replace these Ech-A settings if the attempt to restore the use of Ech-A fails. All observations will be made using the Small Science Aperture, unless the attempt to restore image quality through the installation of COSTAR fails; if the current degraded image quality is still in effect for these observa- tions, then we will use the Large Science Aperture and accept some loss of resolving power. Platinum calibration lamp exposures will be obtained at a few settings, to aid in analyzing molecular band structure. Substepping will be used, along with the FPSLIT feature, to minimize fixed-pattern noise due to diode-to-diode sensitivity variations. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The research goals of this proposal require ultraviolet spectra having high S/N and high spectral resolution. The only existing instrument that could contribute toward these goals is the IUE, but the throughput of the IUE is inferior to that of the HST/GHRS combination, and the data from the IUE are inferior in S/N and spectral resolution as well. We do have IUE data for our target star, and these data will supplement the information that we obtain with the HST (for example, the IUE data have provided information on the extinction curve of the star, and will also yield equivalent-width measures of strong lines, which can be applied toward a curve-of-growth analysis in which data from IUE and HST are combined). But the IUE spectra cannot be used to accomplish any of the goals given in Section 2 of this proposal. We are proposing observations of 19 wavelength settings using the Echelle modes of the GHRS. We have computed exposure times based on the UV fluxes obtained by the IUE, the sensitivity curves given in the Cycle 4 GHRS User's Manual, and our required S/N levels (ranging from 30 for strong atomic lines up to 300 for very weak features such as the C II] line at 2325A). The table below lists the exposure times. ============================================================= Wavelength S/N Exposure time -------------------------------------------------------------- 1240.3A 100 70 min. 1262.0 50 15 1279.2 100 30 1288.2 100 30 1304.2 100 35 1335.5 50 10 1342.0 100 35 1358.9 100 45 1370.5 100 40 1414.0 200 200 1706.4 50 11 1806.7 50 20 2026.0 50 20 2313.0 100 20 2326.0 300 200 2369.0 100 25 2582.0 200 65 3078.0 100 80 ___ 951=15.85 hrs ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. none ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. none ------------------------------------------------------------------------------------ 8. Additional comments or special requests. We stress that we view this proposal as a vital step in a continuing program to explore the properties of interstellar clouds that bridge the gap between the diffuse clouds that have already been fairly well understood, and the dark clouds which are known only through their radio (and in some cases infrared) emission lines. We also stress the unique character of the X Per line of sight, in that it has perhaps the highest total molecular column densities of any diffuse cloud yet observed, but at the same time is bright enough in the UV to permit the acquisition of high-quality data in a modest amount of time. We also wish to stress the long history of our combined efforts to explore these interstellar cloud regimes; all five of us have been working toward this end for years, and have accumulated a legacy of data on the physics and chemistry of the translucent clouds. Page 4 ------------------------------------------------------------------------------------ 9. Description of previous HST work. Our previous program was entitled "Physical and Chemical Processes in Dense Interstellar Clouds" (Program ID Number 2415). This study, for which the first data were obtained in April of last year, consists of the detailed analysis of a single dense-cloud line of sight (toward the star HD154368), with the aims of determining the overall atomic and molecular composition of the cloud, as well as physical conditions which can be derived from fine structure atomic and molecular rotational populations. There is a strong connection between this study and the one now being proposed, since the present proposal is a follow-on in which we are asking for GHRS observations designed to further explore the physics and chemistry of dense clouds. We also were placed in the "moderate priority" category for Cycle 3 (but awarded a minimal amount of observing time, barely enough to observe a half dozen lines in a single target, HD21483) for a follow-on program; as yet these observations have not been scheduled. In addition one of us (T.P.S.) was awarded "supplemental" status for another program (no word yet as to whether observations will be done) and two of us (E. F. v.D. and J.H.B.) have been awarded Cycle 3 time for a study of high-altitude clouds; again, no Our Cycle 1 program on physical and chemical processes in dense clouds (ID2415) mentioned above, and its Cycle 3 continuation, are the only existing programs related to the present proposal. Each is a study of a single cloud (toward the stars HD154368 and HD21483, respectively), and each has similar goals to those of this proposal. As explained in the text, our overall aim is to analyze a few selected clouds for comparison with each other (e.g. note the large contrast in extinction curve type between X Per, which has low UV extinction, and our previous two targets which have steep UV extinction). The only data obtained so far are the HD154368 observations, which are not yet complete due to a loss of data in transmission (a re-observation of the missing wavelength settings should be scheduled soon). Our analysis so far shows: (1) high data quality for all settings; (2) clear detection of OH; possible detection of CS; strong CO bands (at G160M resolution); (3) high C I column density (in excess of 10(15) cm-2); and (4) accurate column densities of numerous atomic species. We expect to complete a major paper on the data as soon as the missing wavelength settings have been re-observed; most of the work will be done this summer. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The University of Colorado will provide academic time for the PI, Theodore P. Snow, as well as access to the Regional Data Analysis Facility. In addition, the University of Colorado, through the Center for Astrophysics and Space Astronomy, will provide access to computer systems, both hardware and software, as needed in support of the data analysis for the proposed study. This support includes a variety of computer programs developed previously for the analysis of interstellar absorption lines, as well programs currently under development for HST research by other Colorado personnel. Thus the proposed research program using the HST will benefit fully from the accumulated experience of Colorado astronomers, and will be provided full access to all facilities and systems developed for this purpose. Each Co-Investigator will be supported by his or her home institution as well, through academic-year salary and through access to local resources. In each case, these resources include existing computer systems and associated support. Existing software for analyzing data and for computing chemical and physical models (particularly at Leiden and Arizona) will be available and will be applied to the analysis of our proposed HST data. ------------------------------------------------------------------------------------ 11. Address Information Page 5 Name: THEODORE P SNOW Category: PI Institution: 1762 Address: CENTER FOR ASTROPHYSICS AND SPACE ASTRONOMY CAMPUS BOX 389 City: BOULDER State: CO Zip Code: 803090389 Country: USA Telephone: (303) 492-4050 Telex (or e-mail): snow@casa.colorado.edu ------------------------------------------------------------------------------------ Name: THEODORE P SNOW Category: CON Institution: 1762 Address: CENTER FOR ASTROPHYSICS AND SPACE ASTRONOMY CAMPUS BOX 389 City: BOULDER State: CO Zip Code: 803090389 Country: USA Telephone: (303) 492-4050 Telex (or e-mail): snow@casa.colorado.edu ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5487 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD24534 A,104, G, RA = 3H 55M 23.0S +/- 0.1S, 2000.0 V = +15 1 V = 6.39 +/- 0.3 508, 513 DEC = +31D 2' 44.7" +/- 0.5" 2 TYPE=O9.5PE 3 B-V = 0.30 +/- 0.03 4 E(B-V) = 0.59 +/- 0.1 5 F-CONT(1240) = 40 +/- 5 E-12 6 F-CONT(1262) = 60 +/- 5 E-12 7 F-CONT(1279) = 64 +/- 5 E-12 8 F-CONT(1288) = 68 +/- 5 E-12 9 F-CONT(1304) = 72 +/- 5 E-12 Comments: F-CONT(1414) = 76 +/- 5 E-12 F- 10 F-CONT(1359) = 75 +/- 5 E-12 CONT(1706) = 60 +/- 5 E-12 F-CONT(1806) = 43 +/- 5 E-12 F-CONT(2026) = 15 +/- 3 E-12 F-CONT(2326) = 18 +/- 3 E-12 F-CONT(2369) = 18 +/- 3 E-12 F-CONT(2582) = 20 +/- 3 E- 12 F-CONT(3078) = 19 +/- 3 E-12 F- CONT(1370) = 80 +/- 5 E-12 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5487 [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD24534 HRS ACQ 2.0 MIRROR-A2 LOCATE=YES 1 9S 35 1 1 ONBOARD ACQ FOR SEARCH-SIZE=3 1.100 BRIGHT=RETURN CYCLE 4 / 1-37 ------------------------------------------------------------------------------------------------------------------------------------ 1.1 HD24534 HRS ACQ/ 0.25 MIRROR-A2 SEARCH-SIZE=5 1 25S 35 1 1 ONBOARD ACQ FOR PEAKUP 3.000-21.000 ------------------------------------------------------------------------------------------------------------------------------------ 3 HD24534 HRS ACCUM 0.25 ECH-A 1240.3 FP-SPLIT=STD 4 1000S 100 5 1 STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ 5 HD24534 HRS ACCUM 0.25 ECH-A 1262.0 FP-SPLIT=STD 1 850S 50 6 1 STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ 7 HD24534 HRS ACCUM 0.25 ECH-A 1279.2 FP-SPLIT=STD 2 850S 100 7 1 STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ 9 HD24534 HRS ACCUM 0.25 ECH-A 1288.2 FP-SPLIT=STD 2 900S 100 8 1 STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ 11 HD24534 HRS ACCUM 0.25 ECH-A 1304.2 FP-SPLIT=STD 2 1000S 100 9 1 STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ 13 HD24534 HRS ACCUM 0.25 ECH-A 1335.5 FP-SPLIT=STD 1 600S 50 9 1 STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ 15 HD24534 HRS ACCUM 0.25 ECH-A 1342.0 FP-SPLIT=STD 2 1000S 100 10 1 STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ 17 HD24534 HRS ACCUM 0.25 ECH-A 1358.9 FP-SPLIT=STD 3 850S 100 10 1 STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ 19 HD24534 HRS ACCUM 0.25 ECH-A 1370.5 FP-SPLIT=STD 2 1100S 100 1 STEP-PATT=7 Comments: S_TO_N ESTIMATE 100 FLUX REF. #01 IN TARG. LIST COMMENT_9 ------------------------------------------------------------------------------------------------------------------------------------ 21 HD24534 HRS ACCUM 0.25 ECH-A 1414.0 FP-SPLIT=STD 10 1100S 200 1 STEP-PATT=7 Comments: S_TO_N ESTIMATE 200 FLUX REF. #01 IN TARG. LIST COMMENT_1 ------------------------------------------------------------------------------------------------------------------------------------ 21.5 HD24534 HRS ACQ 2.0 MIRROR-A2 LOCATE=YES 1 9S 35 1 1 ONBOARD ACQ FOR SEARCH-SIZE=3 21.6 BRIGHT=RETURN CYCLE 4 / 1-37 ------------------------------------------------------------------------------------------------------------------------------------ 21.6 HD24534 HRS ACQ/ 0.25 MIRROR-A2 SEARCH-SIZE=5 1 25S 35 1 1 ONBOARD ACQ FOR PEAKUP 23.000-37.000 ------------------------------------------------------------------------------------------------------------------------------------ 23 HD24534 HRS ACCUM 0.25 ECH-B 1706.2 FP-SPLIT=STD 1 660S 50 1 STEP-PATT=7 Comments: S_TO_N ESTIMATE 50 FLUX REF. #01 IN TARG. LIST COMMENT_2 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5487 [ 8] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 25 HD24534 HRS ACCUM 0.25 ECH-B 1806.7 FP-SPLIT=STD 1 1145S 50 3 1 STEP-PATT=7 Comments: S_TO_N ESTIMATE 50 FLUX REF. #01 IN TARG. LIST COMMENT_3 ------------------------------------------------------------------------------------------------------------------------------------ 27 HD24534 HRS ACCUM 0.25 ECH-B 2026.0 FP-SPLIT=STD 1 1100S 50 1 STEP-PATT=7 Comments: S_TO_N ESTIMATE 50 FLUX REF. #01 IN TARG. LIST COMMENT_4 ------------------------------------------------------------------------------------------------------------------------------------ 29 HD24534 HRS ACCUM 0.25 ECH-B 2313.0 FP-SPLIT=STD 1 1145S 100 1 STEP-PATT=7 Comments: S_TO_N ESTIMATE 100 FLUX REF. #01 IN TARG. LIST COMMENT_5 ------------------------------------------------------------------------------------------------------------------------------------ 31 HD24534 HRS ACCUM 0.25 ECH-B 2326.0 FP-SPLIT=STD 10 1200S 300 1 STEP-PATT=7 Comments: S_TO_N ESTIMATE 300 FLUX REF. #01 IN TARG. LIST COMMENT_5 ------------------------------------------------------------------------------------------------------------------------------------ 33 HD24534 HRS ACCUM 0.25 ECH-B 2369.0 FP-SPLIT=STD 2 700S 100 1 STEP-PATT=7 Comments: S_TO_N ESTIMATE 100 FLUX REF. #01 IN TARG. LIST COMMENT_6 ------------------------------------------------------------------------------------------------------------------------------------ 35 HD24534 HRS ACCUM 0.25 ECH-B 2582.0 FP-SPLIT=STD 4 925S 200 1 STEP-PATT=7 Comments: S_TO_N ESTIMATE 200 FLUX REF. #01 IN TARG. LIST COMMENT_7 ------------------------------------------------------------------------------------------------------------------------------------ 37 HD24534 HRS ACCUM 0.25 ECH-B 3078.0 FP-SPLIT=STD 4 1200S 100 1 STEP-PATT=7 Comments: S_TO_N ESTIMATE 100 FLUX REF. #01 IN TARG. LIST COMMENT_8 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5487 [ 9] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters LOCATE=YES SEARCH-SIZE=3 BRIGHT=RETURN SEARCH-SIZE=5 FP-SPLIT=STD STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 20.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ABSORPTION LINES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 1.100; CYCLE 4 / 1-37 ONBOARD ACQ FOR 3.000-21.000; ONBOARD ACQ FOR 21.6; ONBOARD ACQ FOR 23.000-37.000; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-A2 ECH-A ECH-B ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD24534 ------------------------------------------------------------------------------------------------------------------------------------