<=== observer ===> "DLEMKE",\ "Lemke,D.",\ "",\ "Max-Planck-Institut fur Astronomie",\ "Konigstuhl 17",\ "",\ "D-69117",\ "Heidelberg",\ "Germany",\ "49 6221 528259",\ "49 6221 528246",\ "lemke@mpia-hd.mpg.de" <=== proposal ===> "ISDUST12",1,2,\ {"diffuse interstellar medium","dust properties","molecular clouds"},\ {"Mezger,P.G.","Volk,H.","Kratschmer,W.,H.","Abolins,J.",\ "Mattila,K.","Haikala,L.","Liljestrom,T.","Guertler,J.","Henning,Th.",\ "Pfau,W."," Friedemann,Ch.","Reimann,H.-G."," Leger,A.", "Laureijs,R.",\ "Heske,A.","Prusti,T.","Burgdorf,M.", "Puget,J.-L.","Falgarone,E."} <=== title ===> Interstellar dust emission Part 12 <=== abstract ===> SCIENTIFIC ABSTRACT The aim of this proposal is to investigate the properties and life cycle of dust throughout the universe. We intend to fully study with ISOPHOT the dust in objects, too faint to be observed in the infrared by any other means than a cold telescope in space equipped with a sensitive photometer. This proposal will take advantage of the full spectral range 2.5-240 micrometres. We will utilize other studies of the central program (where often dust is not the scientific target) with the goal of building up a coherent data base for dust properties in different objects and locations. ISOPHOT has unique capabilities for the study of dust in the following two research areas and these have the highest priority: 1. The properties of dust in the cirrus clouds. 2. Search for and properties of very cold dust (ca. 10 K). OBSERVATION SUMMARY We emphasize that the various inter- and circumstellar sub-studies of this proposal will be analyzed and summarized with the goal to gain a comphrehensive picture of dust in the universe from the solar system to intergalactic space. The observational and technical approach is for most of our sub-studies similar, and is connected to the problems of measuring faint surface brightnesses and separating them from the often much brighter zodiacal emission. Observing parameters (e.g.filters) and target lists for the mapping are given separately under the Section Scientific_justification. 1. Cirrus and related clouds(autumn launch 72382 s/spring launch 72469s) Faint cirrus and Gas heating in cirrus/translucent clouds: Abundances and properties of the various dust particles ("PAH"s, small, large) will be studied in different areas of cirrus clouds. One of the targets, the Ursa Major Cloud, has areas which consist mainly of HI, the other target, G300.2-16.8 (Chamaeleon), is associated with molecular gas. L1780 (autumn launch) and L1642 (spring launch) contain a molecular gas core and associated HI gas with a distribution different from the molecular gas. Only PHT -P/C multifilter photometry is sensitive enough for these sources. Galactic line-of-sight, Reflection nebulae and Bright molecular filaments; study of the "PAH"s with PHT-S in cirrus and cirruslike emission: (1) A long galactic line of sight at G28.6+0.8, and a reference position at G31.5-3.8 will be observed. (2) Two reflection nebulae with different surface temperature of the central star (17000 K for NGC7023, 6800K for VdB133) will be studied in order to see differences in the "PAH" features and continumm emission. (3) Properties of dust particles (freshly) exposed to enhanced UV-radiation fields near hot stars and the gas heating will be studied in a bright cirrus- like molecular gas filament, the northern edge of the rho Ophiuchii cloud (autumn launch) or part of the lamda Orionis ring (L1582)(spring launch). 2. Mapping of cold dust in dark clouds at 90 and 200 microns(78037 s/ 72717 s) The distribution and properties of dust in nearby molecular clouds. Especially we are searching for condensations of very cold dust and for very early phases of newly-born (proto)stars. We will study the connection of dust distribution and dust properties to the presence of newly-formed stars. 3. Multi-filter photometry of cold dust in dark clouds (26134 s/26134 s) Locations with different degrees of star formation activity and optical extinction,and positions probably representative for very cold dust. L183 (autumn launch) and L1521B (spring) are clouds with high optical extinction and no star formation known. Chamaeleon I is a molecular cloud which has areas with different degrees of star formation. 4. Spectrophotometry of dust emission from circumstellar environments (6568 s/5952 s) We include planetary nebulae, IRAS sources showing a strong 21 micron dust feature, oxygen rich giants, one OH/IR star (CRL 2199), and one carbon rich post AGB star (CRL 618). The objects cover different strengths of the unidentified infrared features at 21 micron and 30 micron. Another important aspect is the search for the C60 molecule in the circustellar space (strong spectral lines at 7.1, 8.8 micron). We will test the hypothesis that the Very Broad Structure in the interstellar extinction curve is caused by dust in circumstellar environment. 5. Dust emission from the Magellanic Clouds(10934s/10934s) The metallicity, the dust-to-gas ratio and the UV radiation field in the Magellanic clouds are known to be very different from the Galaxy. For each of the Magellanic Clouds, 3 positions on cold and warm sources have been chosen to derive the spectral distribution of the surrounding extended component. In addition, the molecular cloud complex N159 will be mapped. 6. Searches for cold dust in intergalactic and high velocity clouds (9772 s/9772s) Linear raster strip scans are made at 120 and 180 microns across three objects, representative of environments where dust has so far not been detected by IRAS or any other means: Leo Intergalactic Cloud, Coma Cluster of Galaxies, and the (galactic) MI High Velocity Cloud. <=== scientific_justification ===> Time distribution for autumn launch targets (whole proposal) Team top 40% second 30% last 30% total time --------------------------------------------------------------------- PHT 57873 25964 22790 106627s = 29.62h SOT 28800 21600 21600 72000s = 20.0 h JLP 10000tbc 7600tbc 7600tbc 25200s = 7.0 h --------------------------------------------------------------------- Total 96673 55164 51990 203827 = 56.62 h Time distribution for spring launch targets (whole proposal) Team top 40% second 30% last 30% total time --------------------------------------------------------------------- PHT 56807 21433 22560 100800s = 28.00h SOT 28800 21600 21600 72000s = 20.0 h JLP 10000tbc 7600tbc 7600tbc 25200s = 7.0 h --------------------------------------------------------------------- Total 95607 50633 51760 198000s = 55.00h OBSERVING PARAMETERS AND TARGET LISTS ================================= Section 1. Cirrus and related clouds ================================= Faint cirrus: Two faint cirrus clouds are to be observed with multi-filter photometry with PHT-P (AOT17/18/19) and PHT-C (AOT37/38/39). In UMa two ON-positions and two REFERENCE-positions are observed, in G300.2-16.8 three ON-positions and two REF-positions. In the near and mid-infrared the cirrus signals to be measured are only a few per cent of the zodiacal foreground intensity. This has lead us to adopt measuring cycles as follows: UMa: Cycle A: ref1 ref1 on1 on2 ref2 ref1 on1 on2 ref2 ref1 on1 on2 ref2 Cycle B: ref1 ref1 on1 on2 ref2 ref1 on1 on2 ref2 Cycle C: ref1 ref1 on1 on2 ref2 G300.2-16.8: Cycle B: ref1 ref1 on1 on2 on3 ref2 ref1 on1 on2 on3 ref2 Cycle C: ref1 ref1 on1 on2 on3 ref2 For each filter a separate sparse map is performed according to Cycle A,B or C. The sparse maps are concatenated. We use the following set of filters to cover both the "PAH" lines in the near- and mid-IR as well as the mid- and far-IR energy distribution. Wide beam will be used, ie. 180" for PHT-P, and full camera frame (pixels co-added) for PHT-C100 and -C200: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Filter P 3.29 3.60 4.85 7.3 7.7 10.0 11.3 11.5 12.8 16 20 25 60 100 Cycle(UMa) A A A C C A B B B B B B C C Cycle(G300) B B B C C B B B B B B B C C Integr.time 64 64 64 32 32 32 32 32 32 32 32 32 32 32 Filter C 70 120 135 200 Cycle C C C C Integr.time 32 32 32 32 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - For a limited set of filters(P7.3,P25,P100) we will make measurements using the 99" aperture in order to match the LWS aperture. LWS has agreed to observe the same positions as PHT. Gas heating in cirrus/translucent clouds: In order to study the dust emission in cirrus/translucent clouds, especially with regard to the gas heating mechanism, we will perform multifilter PHT-P/C photometry of one cloud (L1780 for autumn, L1642 for spring launch). We include the most important "PAH" features as well as filters to measure in detail the far-IR energy distribution: Filter P 7.3 10.0 11.3 11.5 20 60 C 60 70 120 200 Integration time per filter is 32 sec. In L1780 a raster strip scan (AOT P03+P22) with 13 positions will be performed centered at R.A.=15:37:01 Decl.= -7:03:0 (1950.0) with a tilt angle of 104.5 deg (N to E). This scan passes through the different maximum regions ("cold dust",100 microns, 25 microns, 12 microns) in the cloud. At the NW end of the scan a good back- ground position is reached. The scan will be run through twice: first from NW to SE, and then, shifted by 90", back from SE to NW. This measuring method will guarantee a good control of the detector drift effects. In case of spring launch the cloud L1642 will be observed using sparse mapping (cycle B) as described above for UMa cirrus. Cirrus along a galactic line-of-sight: PHT_S is used to measure both the ON-position G28.6+0.8 and one REFERENCE position G31.5-3.8 some 5 deg away using 2048 sec integration time for both. In addition PHT-P photometry is to be carried out in the filters P3.6,7.7,11.3,12.8,16,20,25,60,100, and C135,and 200 with 32 sec integration time using absolute photometry (P05/P25). FIXTIME OBSERVATIONS are needed to get the ON and REF positions measured during the same orbit (to have the same zodiacal emission ). Suitable times are: orbit 120 +- 20 (autumn launch) orbit 140 + - 2 (spring launch). Reflection nebulae: Two reflection nebulae will be observed in the same way as G28.6+0.8 except that the PHT_S integration times will be 128 sec and 256 sec. For NGC7023 PHT-P/C photometry will be performed with 23" aperture and 32 sec integration time for the filters P3.6,7.7,12.8,16.0,20,25, and PHT-C photometry with filters C60,70, 90,120,135, and 200. For VdB133 the filters are P3.6,7.7,25 and C60,100, and 200. Bright molecular filaments: The filaments are bright enough to enable PHT-S observations: in rho Oph 2 on- positions plus one reference with 1024sec integration time. Each position will in addition be observed with multifilter photometry wit 32 sec integration time: P3.6,7.7,12.8,16,20,25,60, and C60,70,100,135,and 200. In the case of L1582 three ON-positions plus 2 REFs are observed with PHT-S with 1024 sec integration time. Photometry is performed with 32 sec integration time in the filters: P3.6,7.3,12.8,16,20,60, and C60,70,90,135,and 200. ================================================================= Section 2. Mapping of cold dust in dark clouds at 90 and 200 microns ================================================================== The far_IR mapping of dark clouds will be performed using the raster mapping AOT P22, for which we select the following parameters: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Detector C200 C100 Step in Y-direction 180" 135" Step in Z-direction 180" 92" Integration time per raster position(sec) 16 10 Typical surface brightness(MJy/sr) 15 10 S/N for single pixel 280 200 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Mapping proceeds along legs which are parallel to the S/C Y-axis. Along each leg good linking between the raster points is achieved since the detectors are gathering data also during the micro-slews between the raster positions. Along the Z-axis linking of the subsequent legs is achieved by one overlapping pixel row in C100. For C200 no overlapping in Z-direction is foreseen. We define the areas to be mapped in terms of a circle which will be circumscribed by the square which is being mapped. An exception is the cloud L1641, for which the mapping is performed parallel to the R.A. and Decl. axes. Background positions: Since the molecular clouds extend in most cases beyond the mapped area, a separate measurement is needed to determine the background level. For this purpose sparse maps (AOT P37/38/39) will be observed both at 90 and 200 microns including a few positions inside the area mapped with P22 and a few dark OFF positions inside the 1.5 x 1.5 deg allowed area. Zodiacal emission gradients over the sparse map area are not severe, since the ZL background is only of the order of 2 to 4 and 0.5 to 1 MJy/sr at the wavelengts of 90 and 200 microns, respectively. Table 1. Mapping of cold dust in molecular clouds Cloud Field Center Diam. Int. Progr. R.A. Decl. time h m s o ' " ' (h) -------------------------------------------------------------------------------- L1457 @1 02:54:37 20:23:30 24.5 1.6 2 L1457 @2 02:55:50 20:15:30 23 1.6 2 Taurus/L1521 04:21:08 26:30:00 30 1.0 2 ChaI North 11:08:20 -76:18:00 12 0.5 2 ChaI Centre 11:06:30 -77:12:00 39.5 3.9 1 2 ChaI South 11:03:00 -77:35:00 19.5 1.2 1 2 ChaIII 12:48:20 -79:19:10 30 2.3 2 ChaIII/TPN 12:41:19 -78:32:00 12 0.5 1 2 L1780 15:37:33 -07:02:50 39.5 3.9 1 L183 15:51:46 -02:46:40 30 2.5 1 R CrA/N 18:58:56 -37:03:54 21 1.5 1 R CrA/S 18:58:56 -37:03:54 12 0.5 1 -------------------------------------------------------------------------------- Table 2. Mapping of cold dust in molecular clouds Cloud Field Center Diam. Int. Progr. R.A. Decl. time h m s o ' " ' (h) -------------------------------------------------------------------------------- Polaris 01:45:07 87:27:20 30 2.1 1,2 Perseus 03:07:27 30:05:00 30 2.1 2 Taur/Heiles2 04:38:00 25:41:00 42 4.3 2 Taurus/L1538 04:45:58 25:19:30 25 1.8 2 L1512 05:00:54 32:39:00 12 0.5 2 L1630/NGC2071 tbd 18 2 L1630/NGC2068 tbd 18 2 L1630/NGC2024 tbd 21 4.9 2 L1630/NGC2023 tbd 18 2 L1630/LBS23 tbd 18 2 Orion 05:32:49 -05:25:10 15 0.7 2 L1641 05:33:52 -06:23:53 30x9 0.8 2 G300-15 11:52:00 -78:51:00 20 1.1 1 RhoOph/Main 16:23:30 -24:20:00 48 5.4 1 RhoOph/IR1629 16:29:22 -24:20:10 15 0.7 1 RhoOph/East 16:36:40 -24:05:00 15 0.7 1 Serpens 18:27:25 01:07:30 36 3.1 1 R CrA 18:58:56 -37:05:00 39 3.6 2 -------------------------------------------------------------------------------- REMARK: The targets in Table 2 will be studied collaboratively by the PHT-, SOT-, and JLP-teams. This target list will be shortened to a total of 7.0 hours. =========================================================== Section 3. Multi-filter photometry of cold dust in dark clouds =========================================================== A representative set of molecular cloud positions will be observed in the following PHT-P and C filters: Filter P 3.6 4.85 7.3 7.7 10 11.3 11.5 20 60 Integr.time 128 128 32 32 32 32 32 32 32 Filter C 60 90 135 160 200 Integr.time 32 32 32 32 32 We will observe in one cloud a 30 arc min long raster strip scan (AOTs P03 and P22) with 20 positions, 10 positions going in one direction (from N to S) and 10 positions (shifted by 90" in the E-W direction) on the return trip (S to N). This procedure will guarantee best possible control of the detector drifts and zodiacal light gradients and it allows investigation of the changing contributions from different grain populations at dense cloud edges/central parts. The primary target is L183 (autumn launch) and its substitute for spring launch is L1521B. In Chamaeleon I we will observe 8 positions along a raster strip scan of length 24 arc min (AOTs P03 and P22). In addition,two OFF-positions outside the cloud are oberved, concatenated with the strip scans. For the Cha I measuring cycle the filters P3.6 and P4.85 are not included. ========================================================================== Section 4. Spectrophotometry of dust emission from circumstellar environments ========================================================================== We propose to observe these objects with PHT-S (AOT P40) to investigate (unidentified) dust features in the PHT-S wavelength range, and correlate them with the 21 and 30 micron features. PHT-P staring observations at 3.6 and 7.3 micron (AOT P03) are necessary to calibrate the photometry in the PHT-S spectra. All objects are coordinated with LWS. Carrier of the very broad structure (VBS) of interstellar extinction: Measurements with PHT-S with 128 sec on-source integration time,and chopping against an Off-position 30" away. ================================================ Section 5. Dust emission from the Magellanic Clouds ================================================ For each of the Magellanic Clouds, 3 positions on cold and warm sources have been chosen, which are complemented by 2 reference positions in each cloud to derive the spectral distribution of the surrounding extended component. The filter sequence is for all positions: with P1: 4.85, 7.3, 10, 12.8, 16 microns; with P2: 25 microns; with C100: 60, 100 microns; with C200: 160, 200 microns. With each of these filter sequences a sparse map will be performed. With an integration time of 32 sec per position per filter S/N of 5 - 10 can be reached, based on: flux densities between 0.3 (at 5 microns) and 1.5 (at 200 microns) MJy/sr have to be detected on background levels between 4 (5 microns) and 100 MJy/sr. N159 will be mapped with two 7 by 7 point rasters, one in the 60 micron filter (C100), one in the 120 and 180 micron filters (C200), with 16 sec integration time per point. ========================================================================= Section 6. Searches for cold dust in intergalactic and high velocity clouds ========================================================================= We propose to make linear raster strip scans with AOT P22 across three objects, the C200 camera will be used with the C_180 and C_120 micron filters. Combination of data at two wavelengths is essential to disentangle the contibution of the galactic foreground cirrus which is expected to be warmer. The spacing of the raster will be 180", integration time is 32 sec per raster position. For Leo and Coma two (crossed) scans of 48 arc min lenth each will be performed. For the MI HVC a single 96 arc min long scan will be performed. For an expected flux of 0.03 MJy/sr we will obtain a S/N of 4 (pixels co-added) or, in fact, even somewhat better since data is gathered also during the micro-slews between raster points. <=== autumn_launch_targets ===> 1, "PHT22", 3.0, "N", "Leo_IGC C_180 ", 10.75000, 12.50000, 1950, 0.000, 0.000, 950, 2 2, "PHT22", 3.0, "N", "Leo_IGC C_180 ", 10.75000, 12.50000, 1950, 0.000, 0.000, 790, 3 3, "PHT22", 3.0, "N", "Leo_IGC C_120 ", 10.75000, 12.50000, 1950, 0.000, 0.000, 790, 4 4, "PHT22", 3.0, "N", "Leo_IGC C_120 ", 10.75000, 12.50000, 1950, 0.000, 0.000, 790, 0 5, "PHT22", 3.0, "N", "Coma_CoG C_180 ", 12.96250, 28.25000, 1950, 0.000, 0.000, 950, 6 6, "PHT22", 3.0, "N", "Coma_CoG C_180 ", 12.96250, 28.25000, 1950, 0.000, 0.000, 790, 7 7, "PHT22", 3.0, "N", "Coma_CoG C_120 ", 12.96250, 28.25000, 1950, 0.000, 0.000, 790, 8 8, "PHT22", 3.0, "N", "Coma_CoG C_120 ", 12.96250, 28.25000, 1950, 0.000, 0.000, 790, 0 9, "PHT22", 3.0, "N", "MI_HVC C_180 ", 11.40000, 43.25000, 1950, 0.000, 0.000, 1646, 10 10, "PHT22", 3.0, "N", "MI_HVC C_120 ", 11.40000, 43.25000, 1950, 0.000, 0.000, 1486, 0 <=== spring_launch_targets ===> 1, "PHT22", 3.0, "N", "Leo_IGC C_180 ", 10.75000, 12.50000, 1950, 0.000, 0.000, 950, 2 2, "PHT22", 3.0, "N", "Leo_IGC C_180 ", 10.75000, 12.50000, 1950, 0.000, 0.000, 790, 3 3, "PHT22", 3.0, "N", "Leo_IGC C_120 ", 10.75000, 12.50000, 1950, 0.000, 0.000, 790, 4 4, "PHT22", 3.0, "N", "Leo_IGC C_120 ", 10.75000, 12.50000, 1950, 0.000, 0.000, 790, 0 5, "PHT22", 3.0, "N", "Coma_CoG C_180 ", 12.96250, 28.25000, 1950, 0.000, 0.000, 950, 6 6, "PHT22", 3.0, "N", "Coma_CoG C_180 ", 12.96250, 28.25000, 1950, 0.000, 0.000, 790, 7 7, "PHT22", 3.0, "N", "Coma_CoG C_120 ", 12.96250, 28.25000, 1950, 0.000, 0.000, 790, 8 8, "PHT22", 3.0, "N", "Coma_CoG C_120 ", 12.96250, 28.25000, 1950, 0.000, 0.000, 790, 0 9, "PHT22", 3.0, "N", "MI_HVC C_180 ", 11.40000, 43.25000, 1950, 0.000, 0.000, 1646, 10 10, "PHT22", 3.0, "N", "MI_HVC C_120 ", 11.40000, 43.25000, 1950, 0.000, 0.000, 1486, 0