Selected Highlights of the Data Archive

The following programs have data available for download and analysis by the astronomy community; select the title of the observation for detailed information on each program and the results achieved. Data analysis tools are provided by the SOFIA Science Center, in addition to tutorials on using these tools to analyze SOFIA processed data. Information about the SOFIA data archive can be found here

Organic Inventories in Young Stellar Objects and Disks with EXES

The 5.5-8 microns spectral region is rich in vibrational and rovibrational transitions of organic molecules and their isotopologues, including pre-biotic molecules. Spectral signatures from water (in particular the ground state v2 vibrational band), formaldehyde, methane, ammonia, CH3, HCN, and more complex organics can be emitted from warm and hot regions around young stellar objects, as well as the inner regions (<a few AU) of protoplanetary disks. High resolution mid-IR spectra are hence an important tool to understand the mechanics of dust grain evaporation in stellar environments, and eventually to retrace chemical evolution during planet formation.

While the 5.5-8 microns region is inaccessible from the ground, it is observable with the EXES instrument aboard SOFIA. Thanks to its high spectral resolution modes up to R~90000, much higher than what Spitzer IRS could offer, profiles of blended and individual transitions can be analyzed to estimate molecular abundances and excitation temperatures. In addition, measurements of the gas velocity through Doppler-shifts can help to identify the source region for each molecule.

Over the past several years, EXES observations have contributed to a rich inventory of mid-IR spectra from YSOs and protoplanetary disks. The available public database includes sources such as: GV Tau's disk (project 05_0097, Carr et al., in prep), and massive protostars AFGL 2136, AFGL 2591 (projects 04_0120/05_0041 - Barr et al. 2020, 2018, Indriolo et al. 2020), Orion IRc2 (project 05_0043/06_0061, Nickerson et al. in prep) and high-mass YSOs NGC 7538 IRS 1 and IRS 9 (project 75_0024).All calibrated data is available from the IRSA SOFIA Archive.

Orion Molecular Cloud (OMC-1)

Combined analysis of mid- and far-IR spectroscopic and photometric data is key to the study of the chemistry, kinetics and thermal structure of star forming regions, probing warm dust as well as ionized and molecular gas. One of the nearest massive star forming regions, OMC-1, is situated just behind the Orion Nebula and has been extensively observed with all SOFIA instruments.

Through the SOFIA public data archive, anyone can access a large number of infrared high-quality infrared maps and spectra of OMC-1. Some of those datasets explore previously never-observed wavelengths, and many cover regions of interest such as the Orion Bar, considered to be the prototypical photon dominated region. These datasets include:

  • HAWC+ photometric and polarization maps at 53, 89, 154, and 214 microns (proposal ID: 70_0609). Chuss et al. (2019) derived the large-scale polarization structure of OMC-1, confirming the global hour-glass shape of its magnetic field. With a spatial resolution of 5-19”, the Orion Bar and other sub-structures can also be clearly resolved.
  • GREAT ionized carbon [CII] velocity-resolved map at 158 microns (proposal ID: 04_0066): this wide maps provide unique information on ISM kinematics near massive stars. Pabst et al. (2019) focused their analysis on the region of the stellar wind-bubble associated to the Orion Veil.
  • FORCAST and FLITECAM imaging of the Orion Bar at 3.3 and 11.2 microns  (proposal ID: 04_0058), targeting PAH's emission signatures and diagnostic of PAH’s size and abundance.
  • FIFI-LS maps of mid-J CO lines between 69 and 200 microns (proposal ID: 03_0044), which can trace the thermal structure of shocked gas.

Other available data include high resolution spectra of dust obscured compact sources observed with EXES, and large mid-IR photometric maps obtained with FORCAST.

Orion nebula

Betelgeuse High Resolution 25 Micron Spectra 2015-2020

An observing program was executed close to the Betelgeuse's V-band minimum in February 2020 under several Director's Discretionary Time (DDT) programs.

These observations obtained with the EXES instrument were focused on high-spectral resolution spectra around 25 microns, encompassing forbidden [Fe II], [S I] and two water absorption features. Similar data were already obtained in 2015 and 2017, allowing evaluations of variations in line flux and width over time, with sufficient resolution (R~50000) to identify gas velocity changes.

Preliminary data appear to show that the water features at 25.24 microns are significantly deeper in 2020 compared to 2017. However, modeling is needed to confirm the celestial origin of the variation of the water features.

Graham Harper, University of Colorado Boulder, and his team demonstrated that [Fe II] and [S I] emission lines, originating from circumstellar regions well above the photosphere, display no significant change from 2015 to 2020 (paper published in ApJL). Their results suggest that while dust heating can be very sensitive to photometric variations, circumstellar gas in the regions probed by [Fe II] and [S I] lines may not be significantly heated by dust.

All EXES Betelgeuse calibrated data, including from 2020 observations, are publicly available on the IRSA archive under program IDs 75_0051, 05_0073, and 02_004.

SOFIA high-resolution spectra of Betelgeuse

Galactic Center Legacy Program

The inaugural Legacy Program used the FORCAST instrument to observe the Galactic Center using the 25-micron and 37-micron bands. The data have unprecedented spatial resolution – six times higher than past observations — resulting in a vastly improved view of warm dust in the center of the galaxy and revealing signatures of star formation in exquisite detail.

FORCAST created high-quality mosaics of the most active star forming portions of the inner ~200 pc of the galaxy with an angular resolution of 2.3" and 3.4" for the 25 and 37 μm observations, respectively. They cover more than 99% of the hard saturated area in the corresponding Spitzer/MIPS mosaic. An overview paper meant to accompany the first survey data release has recently been published in ApJ. The data are available publicly available in the archive for further research. The composite image shows SOFIA data taken at 25 and 37 μm in blue and green, data from Herschel in red (70 μm), and the Spitzer Space Telescope in white (8 μm).

SOFIA Galactic Center Composite

[OI] and CO Maps of Pillars in the Carina Nebula

The Carina Nebula is home to several massive star clusters and more than 65 O stars. The Trumpler 16 cluster, including its famous member eta Carina, is thought to power the winds and radiation responsible for carving out the complex structures seen in Figure 1. Based on the morphology of these structures, this region of the Carina Nebula known as the South Pillars. Because these pillars are likely formed by the strong winds and radiation of massive stars, they are ideal places to investigate the interaction between this stellar feedback and dense molecular gas. Using the fully-sampled and velocity-resolved GREAT maps of these pillars, scientists can probe the kinematics, morphology, and physical conditions within these interesting regions.

GREAT maps of G287P77 in [OI], CO (11-10), CO (8-7), and CO (5-4)

GREAT maps of G287P77 in [OI] (top-left), CO (11-10) (top-right), CO (8-7) (bottom-right), and CO (5-4) (bottom-right). For each map, four panels are shown. The top-left panel shows the channel map at the velocity indicated by the red line in the top-right panel. The top-right panel shows the spectrum at the position indicated by the intersection of the two black lines. The bottom-left panel shows the integrated intensity image summed over the velocities indicated by the yellow shading on the bottom-right. The bottom right shows the average spectrum of the map (if there is a polygon drawn on the bottom-left image, the spectrum is an average over the area of the polygon).

[C II] Map of the M51 Galaxy

The entire galaxy M51 was imaged using both FIFI-LS and GREAT. The FIFI-LS observations took only 7 hr of observatory (wall-clock) time. The image is shown with a surface brightness scale in units of erg/s/cm2/sr. Read more here.

A SOFIA Survey of [C II] in the Galaxy M51. I. [C II] as a Tracer of Star Formation
J.L.Pineda et al (2018), ApJL, 869, L30

SOFIA [C II] Map of M51

30 Doradus

Polarization maps of the star-forming region 30 Doradus in the Large Magellanic Cloud using HAWC+. The maps were taken at 53, 89, 154, and 214 μm, revealing dust emission between 10-100 K and allowing for an inferred morphology study of the magnetic field. Read more here.

"SOFIA Community Science I: HAWC+ Polarimetry of 30 Doradus"
Gordon, et al, 2018, arXiv:1811.03100.

30 Dor plots

Horsehead Nebula [C II] Map

Velocity resolved map of the Horsehead Nebula—a dark nebula and photodissociation region in the Orion Molecular Cloud Complex—using GREAT. The map was taken in the [C II] line at 158 μm. Read more here.

"Kinematics of the Horsehead Nebula and IC 434 Ionization Front in CO and C+"
Bally, John, et al., 2018, AJ, 155, 80.

upGREAT data

SN 2014J Imaging and Spectroscopy

Imaging and grism spectroscopic data to probe the ejecta and surroundings of the bright Type Ia Supernova, SN 2014J, in M82. The observations were taken using FORCAST and the now retired instruments FLITECAM and HIPO. Read more here.

"Observations of Type Ia Supernova 2014J with FLITECAM/SOFIA"
Vacca, W. D., et al., 2015, ApJ, 804, 66.

SOFIA near-IR image of Supernova 2014J
SN 2014J Spectrum
Vacca, W. D. et al., 2015, ApJ, 804, 66.

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