The Circumnuclear Ring (CNR) (11 Slides) – Quintuplet Proper Members (Qpms) (6 Slides)

Home , Pistol Nebula, Quintuplet Cluster

SOFIA/FORCAST Observations of the Galactic Center

Ryan M. Lau SOFIA Community Collaborators: T. L. Herter, M. R. Morris, E. E. Becklin, M. J. Hankins, Task Force Teletalks, J. D. Adams, G. E. Gull, C. P. Henderson, J. Schoenwald February 6, 2013 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Talk Outline

• Background – The Galactic Center – Observations

• Results and Science – The Circumnuclear Ring (CNR) (11 slides) – Quintuplet Proper Members (QPMs) (6 slides) – Pistol Nebula (10 slides)

• Further Work

2 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau The Galactic Center • ~500 pc unique region containing a 4,000,000 solar mass black hole, massive stars, supernovae, and star formation regions QC & Pistol • 10% of present SF activity in Galaxy occurs in GC yet only tiny fraction of a percent of volume in Galactic disk CNR 10 pc • Contains ~4/12 of the LBVs and ~90/240 of Wolf-Rayet stars in galaxy 3 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau The Galactic Center: Inner 50 Pc

• Circumnuclear Ring (CNR) – Dense ring of gas and dust surrounding Sgr A* by 1.4 pc • Quintuplet Cluster (QC) QC & Pistol – ~4 Myr cluster of hot, massive stars – Named after 5 bright IR sources within cluster (we observe 4 of them) • Pistol Nebula CNR – Asymmetric shell of dust and 10 pc gas surrounding the Pistol star – Appears to be shaped by 8 μm Spitzer/IRAC image of the inner interaction with QC winds 50 pc of the Galactic Center 4 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Observations • SOFIA/FORCAST Quintuplet Galactic Center Stars observations conducted during Basic Science flights 63 and 64 QC & Pistol Nebula Pistol on June 4, 2011 and 8, 2011, respectively.

40 pc CNR SOFIA/FORCAST images CNR at 19.7 (blue), 31.5 (green), 37.1 (red) mm

8 μm Spitzer/IRAC image of the inner

50 pc of the Galactic Center 5 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau FORCAST • Facility Instrument – LHe cooled (4.2 K), 700 lbs

• Dual-Channel 256x256 Camera w/ Si BIB arrays – BIB: Blocked-Impurity-Band – 5-25 mm with Si:As array – 25-38 mm with Si:Sb array

• Plate scale: 0.75 arcsec/pixel – 3.23.2 arcmin FOV

• Selectable filters over the 5 - 38 mm range FORCAST commissioning in mid-March 2013 and available for Cycle 1B Above: FORCAST mounted on the SOFIA Telescope observations in early Summer 2013 Below: FORCAST in the DAOF lab 6 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau

FORCASTFilter Profiles Filters 1.0 Filter (mm) R (l/Dl)

0.8 5.3 33 6.3 48 0.6 6.6 34 0.4 7.6 15

Filter Transmission 0.2 8.6 42 11.0 12 0.0 5 6 7 8 9 10 11 12 11.28 56 Wavelength (microns) Filter Profiles 19.5 3.8 1.0 19.7 31.5 37.1 24.4 7.5 0.8 30.6 5.7

0.6 33.4 18 34.8 8.3 0.4 37.1 8.8

Filter Transmission 0.2 Left: Representative FORCAST filter

0.0 curves (not including atmospheric 15 20 25 30 35 40 transmission or detector response). Wavelength (microns) Arrows indicate filters used in GC observations. 7 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Galactic Center Results: The Circumnuclear Ring

QC & Pistol

40 pc

CNR

8 μm Spitzer/IRAC image of the inner SOFIA/FORCAST false color image of the inner 6 pc of the GC at 19.7 50 pc of the Galactic Center 8 (blue), 31.5 (green), 37.1 (red) mm SOFIA/FORCAST Observations of the Galactic Center R. M. Lau The Ring around Sgr A* Face on View Observed View SOFIA/FORCAST

Sgr A* Northern Arm East-West Bar

Observed view of CNR model 1 pc Face-on view of CNR model SOFIA/FORCAST false-color CNR inclined by ~67 degrees and image of CNR

has a radius of 1.4 pc 9 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Observations of the CNR

Deconvolved and reconvolved to 2.5’’ beamsize

Left: Observed SOFIA/FORCAST images of the CNR at different intensity stretches

Right: Deconvolved and reconvolved CNR images

10 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Evidence for Central Heating

a c

b c a

e e d d

Above: 37.1 mm intensity map Shifts in peaks across wavelengths indicate a Upper Right: Intensity line cut through center of ring radial temperature gradient and central heating11 Lower Right: Intensity line cut through south of ring

SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Temperatures Across the Ring • Temperatures range from 70 - 85 K – Consistent with temperature calculations assuming central 7 L ~ 2 x 10 Lsun heating source.

• Fairly uniform temperature around ring – Heating dominated by radiation from central cluster Color temperature map of the inner – No star formation 6 pc of the GC derived from 19.7 and 37.1 µm intensity maps occurring in rung 12 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau CNR Column Density • Column densities range from 0.025 – 0.4 – They peak at the northern and southern clumps

• A majority of the material in this region lies in the ring (not the Northern arm or East-West bar)

• Total CNR gas mass is ~450 Solar masses* Optical depth map at 37.1 mm of the inner 6 pc of the GC. Contours at 0.025, 0.05, 0.1, 0.2, and 0.4 (dark) 13 *Assuming dust to gas mass ratio of 1/100 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Ring Morphology • We can determine the width of the CNR given our 2.5’’ resolution images Rin φo – We can also find the Sky Plane inclination angle θi (67°), θi and inner radius Rin (1.4 pc) • From the width we Line of determine the Sight opening angle φo (14°) h and ring height Cross section through CNR. The h (0.35 pc) orange regions indicate the illuminated region of the ring 14 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau CNR Intensity Model

37.1 µm 37.1 µm MODEL OBS

Model 37.1 µm Intensity map of CNR Observed 37.1 µm Intensity map of Density at inner edge is n = 104 cm-3 the inner 6 pc of the GC Model has been convolved with 2.5’’ Gaussian to match beamsize of the observed image 15 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Model vs Observed 37.1 Intensity Map Radial Line Cuts: East-West

37.1 µm East-West Intensity Line Cut OBS Western Arc 15 Observed

10 Model Intensity (Jy) Intensity

-60 -40 -20 0 20 40 60 Pixel Western Arc Observed 37.1 µm Intensity map of the inner 6 pc of the GC with East- Model vs. Observed 37.1 µm West cut overlaid intensity line cut through CNR Model intensity peak location, width, and value at Western arc are consistent with observed data 16 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Model vs Observed 37.1 Intensity Map Radial Line Cuts: Diagonal

37.1 µm Diagonal Intensity Line Cut OBS Western Arc 15 Observed Model

10 Intensity (Jy) Intensity

-50 0 50 Pixel Western Arc Observed 37.1 µm Intensity map of the inner 6 pc of the GC with Model vs. Observed 37.1 µm intensity diagonal cut overlaid line cut through CNR. Model intensity peak location, width, and value at Western arc are consistent with observed data 17 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Inner Edge “Clumps” • We resolve “clumps” at the inner edge of the CNR

• “Clumps” due to density enhancements (not embedded sources) • n ~ 2-3 x 104 cm-3

SOFIA/FORCAST false color image of the inner 6 pc of the GC at 19.7 • Periodic? (blue), 31.5 (green), 37.1 (red) mm. Inset shows zoom of inner edge “clumps”

18 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau CNR Results Summary • The CNR is heated by central cluster of stars

• Observed temperatures consistent with heating by central source with total luminosity 7 L ~ 2 x 10 Lsun

• No star formation occurring in

CNR

• Dust emission from CNR can be modeled as an inclined ring • Possibly periodic “clumps” occur SOFIA/FORCAST false color image in the inner edge of the CNR of the inner 6 pc of the GC at 19.7 (blue), 31.5 (green), 37.1 (red) mm 19 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Galactic Center Results: The Quintuplet Proper Members*

Quintuplet Proper Members

QC & Pistol

40 pc

*Work lead by Matt Hankins, CNR senior undergrad at UCA

8 μm Spitzer/IRAC image of the inner SOFIA/FORCAST false color image of the Quintuplet cluster at 19.7 (blue), 50 pc of the Galactic Center 31.5 (green), 37.1 (red) mm 20 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau The Quintuplet Proper Members (QPMs) • Quintuplet cluster age ~4 Myrs – Cluster of hot, massive stars – Coeval formation Q9 Q4* Q1 Q2 • QPMs very luminous (L~105 Q3 LSun), cool (600-1200 K) sources with featureless K- band spectra – Extremely dusty

Pistol • Late-type dusty Wolf-Rayet Nebula stars (DWCL) (Figer et al. 1999) SOFIA/FORCAST false color image of 1 pc the Quintuplet cluster at 19.7 (blue), 21 31.5 (green), 37.1 (red) mm *we barely observe Q4

SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Are the QPMs “Pinwheels”? • Tuthill et al. (2006) find QPMs are likely WR + O/B binary

Q4 Q9 systems Q1 – Q2 Box scale: ~2400 AU x Q3 2400 AU

• Q1, Q9, and Q4 were only partially resolved, Tuthill et al. claims they have tighter winding Fig. S1 from Tuthill et al. (2006). angles or have different Background field is from HST/NICMOS near-IR imaging. Inset images of Q2 and orientations Q3 were taken by Keck in the K-band 22 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Spectral Energy Distribution Model Fits

• Models generated by the DUSTY radiative transfer code assuming spherical geometry

• Cool Blackbodies (650- 1000K) added to fit the near-IR for Q1, Q2, and Q9.

• Q1 and Q9 models exhibit different physical properties from Q2 and Q3 models

DUSTY models and model parameters

23 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Implications

• Given the models, Q9 QPMs appear to be Q4 Q1 Q2 quite different from Q3 each other – A shallower density power law for Q1 and Q9 indicate a decreasing mass loss rate

Pistol • Differences in Nebula morphological properties indicate the 1 pc QPMS are in different evolutionary phases? SOFIA/FORCAST false color image of the Quintuplet cluster at 19.7 (blue), 31.5 (green), 37.1 (red) mm 24 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Quintuplet Results Summary

• Spectra reveal different Q9 morphological properties Q4 Q1 amongst QPMs Q2 Q3 • DUSTY model of Q1 and Q9 require an additional cool blackbody to fit near-IR part of observed spectra – Are we looking through Pistol “holes” in the dust shell? Nebula • Some work still needs to be 1 pc done to check robustness of model fits SOFIA/FORCAST false color image of the Quintuplet cluster at 19.7 (blue), 31.5 (green), 37.1 (red) mm 25

SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Galactic Center Results: The Pistol Nebula

QC & Pistol

40 pc Pistol Nebula

CNR

8 μm Spitzer/IRAC image of the inner SOFIA/FORCAST false color image of the Quintuplet cluster at 19.7 (blue), 50 pc of the Galactic Center 31.5 (green), 37.1 (red) mm 26 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau The Pistol Star and Nebula

• Pistol Star is a Luminous Blue Variable (LBV) – One of the most luminous “Barrel” stars in the Milky Way (L~1.6 x “Handle” 6 10 LSun)

– Fairly cool (Teff = 11800 K) Pistol Star • Nebula formed from Pistol star ejecta – Shaped like a pistol due to interaction with QC winds HST/NICMOS image of the Paschen-alpha emission from the Pistol star and nebula 27 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Not Quite a “Pistol” in the Mid-IR…

“Home Plate”

“Baseball Diamond?” “Ballpark?” “Home Plate?”

“Home Plate” on Mars taken by HiRISE 28 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Morphology of the “Pistol” Nebula

Quintuplet Cluster Stars • Optically thin, asymmetric shell – Pistol star displaced from center of nebula

• Northern edged likely Pistol Star shaped by interaction with QC winds based on projected location

1 pc • Also shaped by the ambient 1.4 pc magnetic field (Figer et al.

SOFIA/FORCAST false color image 1999)? of the Pistol Nebula at 19.7 (blue), 31.5 (green), 37.1 (red) mm 29

SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Consistency Across Wavebands

1 pc

SOFIA/FORCAST deconvolved Apparent morphology extremely consistent across images of the Pistol nebula at 19.7, 31.5, and 37.1 µm images 19.7, 31.5, and 37.1 µm (note the filamentary structures within the nebula)

NOT like a classic HII region (compare to the CNR!)

30 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Similarity of Intensity Profiles

Diagonal Intensity Line Cut “Barrel” 2.5 19.7 µm - Red “Barrel” 31.5 µm - Blue 2.0 37.1 µm - Green

1.5 Intensity (Jy) Intensity 1.0

0.5

1 pc 0.0

-20 0 20 Pixel SOFIA/FORCAST deconvolved Similar intensity line profiles across wavebands image of the Pistol nebula at indicate uniform temperature throughout nebula 19.7 µm

31 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau How is the Pistol Nebula Heated?

Gas Emission Dust Emission Because the Pistol star is relatively cool, The Pistol star will contribute much the gas is primarily ionized by hot O and B more to heating the dust than it does Quintuplet cluster stars to the North-East for ionizing the gas 32 of the Pistol (Figer et al. 1999)

SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Pistol Nebula Temperature Map

19/37 CT • Pistol nebula exhibits almost uniform temperature distribution (~100 K) 140 – Slight decreasing gradient from 100 120 east to west – Gradient is consistent with heating by both Pistol and hot QC stars

1 pc • However, the color Error ±12 K temperature is higher than Color temperature map of Pistol nebula derived from 19.7 and what calculations predict for 37.1 µm intensity maps typical silicate grains (~ 70 K)

33 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Introducing a Small Grain Component Grain Size (SGs): 3.25 – 210 Ang Dual grain size distribution (small grains & large grains) Grain Size (LGs): 2.2e4 – 8e4 Ang Models generated using DustEM radiative transfer code Pistol Nebula SED F Large + Small Grains – Blue 16 ISOCAM FORCAST Small Grains – Red 2 10 Large Grains – Yellow 1 1016

15 5 10 TP = 12000 K TQC = 40000 K 6.6 2 1015 LP = 10 L Sun 7.3 LQC = 10 L Sun 15 1 10 dP = 0.6 pc dQC = 1.5 pc 5 1014

2 1014 1 1014 Wavelength m 10 15 20 25 30 35 40 34 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Pistol Nebula Results Summary • Pistol nebula is an asymmetric shell composed of ejecta from the Pistol star • Likely being shaped by interactions with QC winds • Dust in nebula heated by hot QC stars and the Pistol star, itself

SOFIA/FORCAST false color image • Requires dual grain size of the Pistol Nebula at 19.7 (blue), 31.5 (green), 37.1 (red) mm components (large AND small grains) to fit SED 35 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Further Work

• Circumnuclear Ring SOFIA/FORCAST false color – Explore the hydrodynamics in the image of the inner 6 pc of CNR environment to explain the GC at 19.7 (blue), 31.5 “clumps” and striations. (green), 37.1 (red) mm

• Quintuplet Proper Members – Study the formation and evolution of dusty, binary WR systems

• Pistol Nebula – Draw comparison to 2nd LBV SOFIA/FORCAST false nebula in region (Mauerhan et al. color image of 2010), which appears much more Quintuplet Cluster at 19.7 (blue), 31.5 spherically symmetric than the (green), 37.1 (red) Pistol Nebula. mm

36 SunriseThanks! and SOFIA

37 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau

Extra Slides

38 CNR Properties

39 Model Parameters: Dust Properties • 53% Silicate and 47% Graphite type dust grains (dust to gas mass ratio of 1/100) • Grain Size dist: amin – 0.1 µm, amax – 2 µm • Dust density profile: n(r) = n0 (r/Rin)^q – n0 = 10^4 cm^-3 – q = -1.5 • Dust temperature profile: T(r) = T0 (r/Rin)^m – T0 = 80 K These dust properties are checked with – m = -1 DUSTY in comparison with our temperature map from observations

40 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Model vs Observed 37.1 Intensity Map Line Cut: East-West

Observed 37.1 µm Intensity map of Model vs. Observed 37.1 µm intensity the inner 6 pc of the GC with line cut through CNR. Southern East-West overlaid Eastern arm of CNR lies slightly inward of model 41 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Pistol Nebula Spectral Energy Distribution and Model Fit Attempts Observed Pistol SED South F 1015 ISOCAM FORCAST

1014

1013

T = 170 K T = 70 K 1012

1011 m 10 15 20 30