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Observing the Galactic Center with SOFIA

Observing the Galactic Center with SOFIA. Mark Morris, UCLA. SOFIA is the successor to the Kuiper Airborne Observatory, a C141A transport stationed at NASA/Ames 1971 – 1995.

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Observing the Galactic Center with SOFIA

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  1. Observing the Galactic Center with SOFIA Mark Morris, UCLA

  2. SOFIA is the successor to the Kuiper Airborne Observatory, a C141A transport stationed at NASA/Ames 1971 – 1995. SOFIA’s telescope has 7.5 times the collecting area of the KAO telescope, a conventional Cassegrainreflector with a 36-inch mirror.

  3. A few KAO highlights, to make the case for airborne astronomy: The CircumNuclear Disk (the CND), discovered with the KAO (Becklin, Gatley & Werner 1982) H2Yusef-Zadeh et al (HST) J. Davidson et al1992 (using KAO) 90 µm The clumpy disk is heated approximately equally by central stellar cluster of old stars and by the UV flux from the bright young stars in the central cluster. Total UV flux implied: ~107 L.

  4. OI emission peaks in the interior of theCND, so the ionized gas there is mixed with atomic gas, presumably producedby photodissociation. An indication that there is far more gasinside the CND (300 M8) than the ionized gas in Sgr A West (30 M8) 63 µm OI emission measured with the KAO: Jackson et al. 1993FWHM: 22”

  5. Hot dust in the Arched Filaments, ionized & heated by the Arches Cluster 31.5 µm 37.7 µm KWIC on the KAO Latvakoski, H. M.; Stacey, G. J.; Gull, G. E.; Hayward, T. L. 1999

  6. Dotson et al. 2000 and 2003 Far-IR polarimetry ! 50 and 100 µmpolarimetry from theKAO, and 350 µm polarimetry using theHertz polarimeter on the CSO

  7. KAO experience  Airborne astronomy is exceptionally well suited for study of the Galactic center Stratospheric Observatory for Infrared Astronomy: SOFIA • This long-promised replacement for the KAO will carry the torch for the next 20 years. • A Boeing 747SP aircraft modified to accommodate a2.5-meter diameter reflecting telescope <> compare to Herschel – 3.5 m • SOFIA is a joint NASA +DLR sub-orbital observatory • 80% NASA • 20% DLR -- Germany’s Aerospace Agency

  8. USRA (Universities Space Research Association) will manage the science operations of SOFIA - science center: NASA/Ames Research Center - the German SOFIA science center is in Stuttgart • NASA’s Dryden FlightResearch Center willoperate the aircraft • Operating altitude: 37,000 – 45,000 ft.

  9. Advantages of SOFIA: • Long duration, once it starts • Portable observatory • Flexibility of operation, and instrument swapping • Real-time observer participation • High spectral resolution • High spatial resolution in mid to far IR, compared to any other existing platform. Disadvantages: timing, with respect to Herschel cost of jet fuel

  10. Telescope in Aircraft

  11. Looking aft toward the pressure bulkhead & telescope assembly

  12. Observatory Layout

  13. First Science Instruments: FORCAST Faint Object Infrared Camera for the SOFIA Telescope A mid-IR camera, 256 x 256 pixels, operating at 5-40 µm GREAT German Receiver for Astronomy at Terahertz Frequencies A heterodyne spectrometer operating at 60-200 µm other 1st generation instruments: HAWCHigh-resolution Airborne Wideband Camera EXESEchelon-Cross-Echelle Spectrograph FIFI-LSField Imaging Far-Infrared Line Spectrometer CASIMIRCaltech Submm Interstellar MediumInvestigations ReceiverFLITECAMFirst Light Infrared Test Experiment Camera SAFIRESubmillimeter and Far-Infrared ExperimentHIPOHigh-speed Imaging Photometer for Occultations

  14. SOFIA spectroscopy. EXES:[S III] 18.7 µm, [S I] 25.2 um, [O IV] 25.9 µm; H2 @ 17 & 28 µm R~20,000 (15 km/s) FIFI LS:[O III] 52, 88 µm, [O I] 63 µm, R~3000 (100 km/s) [O I] 145 µm, [C II] 158 µm, CO J=14-13, 17-16, 22-21, 27-26 R~2000 GREAT:[OI] 63 um; R~20,000 (15 km/s) CASIMIR:CO 8-7, 9-8, 10-9, 12-11, HCN 6-5, 8-7, 9-8, 12-11, 13-12, HCN 14-13, 16-15, HCO+ 11-10

  15. The Galactic Center from Spitzer

  16. Galactic center issues that SOFIA can address: I. Thermal balance of GC clouds – what is the dominant heating source? Candidates: shocks, X-rays, dissipation of hydromagneticwaves Shock heating – investigate with the 63 and 149 µm fine structure lines of OI, produced in both shocks and PDRs. <> But compare to [CII] 158 µm line, which is much less affected by shocks. <> Use the intensity ratio of the two [OI] lines to control for density II. Heat flow through the GC ISM – dust and gas luminosities III. Magnetic field measurements <> equip the HAWC far-IR imager with a polarimeter to measure alignment direction of dust grains using the polarization vector of their thermal emission. IV. Chemistry – into the THz regime

  17. SOFIA Schedule • First open door flight: November 2009 • First Science: August 2010 • Full operations: 2014 • 160 flights per year, 8-hr flights • Operation for 20 years Let’s go……

  18. Flight Profile 1 Performance with P&W JT9D-7J Engines: Observations - start FL410, duration 7.1 Hr ASSUMPTIONS ZFW 381,000 LBS. ENGINES OPERATE AT 95% MAX CONT THRUST AT CRUISE 25,000 LBS. FUEL TO FIRST LEVEL OFF CLIMB TO FIRST LEVEL-OFF AT MAX CRUISE WT LANDING WITH 20,000 LBS. FUEL BASED ON NASA AMI REPORT: AMI 0423 IR BASED ON 747 SP FLIGHT MANUAL TABULATED DATA STANDARD DAY PLUS 10 DEGREES C CRUISE SPEED-MACH .84 FL430, 2.9 Hr GW 458.0 FL410, 4.2 Hr GW 542.0 CRUISE 52,000 LBS.FUEL F.F. 17,920 LBS/HR. CRUISE 84,000 LBS. FUEL F.F. 20,200 LBS/HR. DESCENT GW 406.0 5,000 LBS. FUEL .5 HRS. CLIMB 25,000 LBS. FUEL .5 HRS. TOTAL FUEL USED = 169,000 LBS. (24,708 Gallons) TOTAL CRUISE TIME = 7.05 HRS. TOTAL FLIGHT TIME = 8.05 HRS START, TAXI, TAKEOFF GW 570.0 3000 LBS TAXI FUEL LANDING GW 401.0 20,000 LBS FUEL

  19. Flight Profile 2 Performance with P&W JT9D-7J Engines: Observations - start FL390, duration 10.2 Hr ASSUMPTIONS ZFW 381,000 LBS. ENGINES OPERATE AT 95% MAX CONT THRUST AT CRUISE 25,000 LBS. FUEL TO FIRST LEVEL OFF CLIMB TO FIRST LEVEL-OFF AT MAX CRUISE WT LANDING WITH 20,000 LBS. FUEL BASED ON NASA AMI REPORT: AMI 0423 IR BASED ON 747 SP FLIGHT MANUAL TABULATED DATA STANDARD DAY PLUS 10 DEGREES C CRUISE SPEED-MACH .84 FL430, 2.9 Hr GW 458.0 FL410, 4.2 Hr GW 542.0 CRUISE 52,000 LBS.FUEL F.F. 17,920 LBS/HR. FL390, 3.1 Hr GW 610.0 CRUISE 84,000 LBS. FUEL F.F. 20,200 LBS/HR. DESCENT GW 406.0 5,000 LBS. FUEL .5 HRS. CRUISE 68,000 LBS. FUEL F.F. 21,930 LBS/HR. CLIMB 25,000 LBS. FUEL .5 HRS. TOTAL FUEL USED = 237,000 LBS. (34,650 Gallons) TOTAL CRUISE TIME = 10.15 HRS. TOTAL FLIGHT TIME = 11.15 HRS. LANDING GW 401.0 20,000 LBS FUEL START,TAXI,TAKEOFF GW 638.0 3000 LBS TAXI FUEL

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