High Frequency Radio Emission from Stars within 2pc of Sgr A* F. Yusef-Zadeh Sub-mm Northwestern University

• Overview of some recent measurements

q ~100 WR/O stars: few million yrs old q ~40-100 proplyd candidates few 105-6 yrs old q Bipolar Outflows: few 103-4 yrs

q IRS3: a luminous and extended star

• Conclusions

Collaborators: W. Cotton, M. Royster, D. Kunneriath, M. Wardle, D. A. Roberts, A. Wootten & R. Schoedel Massive Stars: 2 Microns VLT: 2µm A Three-Earths Mass Cloud: G2

Gillessen et •E al. 2009

4” (0.16pc) Massive Stars: 44 GHz (128 MHz BW)

VLA: 7mm A Three-Earths Mass Cloud: G2

•E

Sgr A*

4” (0.16pc) Broad Band Continuum: 35 GHz (8GHz BW) 168 154 156

300 147 146 252 298 185 153 148 133 295 283 121 137 290 141 291 135 136 125 134 282 123 234 118 120 132 179 102 130 158 183 96 139 304 128 109 299 89 296 284 289 280 218 92 97 286 209 131 111 105 160 277 157 119 100 273 72 215 267 152 275 258 244 221 98 103 150 181 268 256 248 222 211 75 777981 163 251 243 212 86 99 247241 225 204 95 263 196 68 107 287 260 242 87 265 245 230 180 15 94 216 197 6663 6771 88 101 220 11 184 4 281 22 142 240 85 12 3 149 155 177 164 124 161166 172 1 2 84 116 144 10 3343 104 151 159 9 35 39 26 21 40 18 27 47 205 187 8 7 90 122 28 5 2425 36 42 5437 6 20 23 29 62 170 13 30 6165 14 38 53 46 217 49 69 219 16 70 5048 17 45 64 140 227 56 41 7376 138 239 207200 60 52 19 34 5955 57 31 32 51 80 228 44 294 58 93 110 78 74 106 83

198 112 259 127 213 108 182 145 91 129 143 214 226 171 250 203 255 232 126 210 238 195

237 115 • Ionized orbiting gas, compact and partially resolved sources • 320 compact radio sources • 1/3 of massive stars have radio counterparts • A number of compact sources with no IR counterparts Massive Stars: 35 and 44 GHz

10–4 10–4

M Radio Cometary ) NIR vs 34 GHz 45 1 GHz – IRS 16NW yr IRS 16NE (M sun 45 vs 34 GHz Ridge sun

(M IRS 16C yr NIR – M Sgr A* 1 ) IRS 13N 10–5 10–5 Magnetar

10–5 10–4 –1 M34 GHz (Msun yr )

• Radio vs IR mass loss rates • Mass loss rate is reduced by a factor of ~10 • Reduce the accretion rate onto Sgr A* • Astrometry, proper motion Low-mass Proplyds: 105-6 yrs

Sgr A* Radio Continuum image at 34 GHz

RC4

RC3 P26

P8

Cometary Features IRS 7E2 Northern Arm IRS 7E1 IRS 7

-20 0 20 40 60 80 0 50 100 150

3.8

• ~ 44 radioP26 sources2800 with cometary •Cometary morphology 3.7 appearance with no near-IR counterparts •Size scale ~500AU FYZ et al. 2015 3.6 2700 P8 2 2 • Size scale ~500AU •[NLy /d ] (GC) ~ [NLy /d ] (Orion) •3.5 [NLy /d2] ~ [NLy /d2] •Protostellar disk candidates (GC) 2600 (Orion) •3.4 Protostellar disk candidates •Multiple sources of illumination

•3.3 Multiple sources2500 of illumination

Arc seconds 3.2 2400 MilliArc seconds

3.1

2300 3.0

2.9 2200

2.8 2100

16.20 16.10 16.00 15.90 14500 14400 14300 14200 14100 14000 13900 Arc seconds MilliArc seconds • Two arguments in favor of protoplanetary disks

• 1) Gas needs to be replenished • t (expansion)~ 240 yrs • 2) Must be bound by self-gravity to be stable against tidal disruption • n(H) ~ 106 cm-3 << Roche density ~ Star Formation near Sgr A*: ALMA DATA

0 100 200 300

1 -29 00 24.5 4

2,3 25.0 5

25.5 2

) 4 3 26.0 sun 1 1 0.1 (M 26.5 disk M

Declination (J2000) 27.0

27.5

28.0

0.01 ç 10 100 28.5 17 45 41.30 41.25 41.20 41.15 41.10 41.05 41.00 40.95 40.90 Tdust (K) Right Ascension (J2000)

•Disk mass 0.03-0.06 Msun Millimeter contours over 7mm •Size scale ~500AU Radio proplyds have mm counterparts •Minimum Mass Solar Nebula ~ 0.01Msun 13CO (2-1) 22 GHz: ALMA c.

•The lobe mass 0.32 Msolar •Momentum rate L/c ~5.7x102 Lsolar •A population of low-mass bipolar outflow sources •Mean dynamical age is 6500 yrs IRS 3: Evolved AGB Star vs a Dusty Young Star

•IRS 3: brightest most extended @8.3µm with R=1” (8000AU) IRS 7 •Asymmetric envelope IRS 3

•No OH masers

•4.5” (0.18pc) from Sgr A*

Sgr A* IRS 3: Evolved AGB Star vs a Dusty Young Star

•a=1.85+/-1.13 between 44, 226 GHz

• a=1.32+/-0.32 between 34, 44 GHz

•a=1.17+/-.33 between 226, 350 GHz

•Consistent with an •AGB star

•Asymmetric shell Millimeter contours over 0.7mm •in the direction of Radio proplyds have mm counterparts •proper motion Tidal Disruption of IRS 3: ALMA DATA

z = − 0.8 pc z = + 0.6 pc

5 •Envelope mass ~ 0.3 Ms0lar

0 •If texpansion ~ torbital then tidal distorted z = − 0.7 pc z = + 0.5 pc •Fluid elements expanding as they 5

orbit Sgr A* Dec (arcsec) ∆ 0

•The strength of distortion: z = − 0.6 pc z = + 0.4 pc IRS 3 is 0.7 pc in front or 0.5 pc behind 5

0 •Radial and tangential velocities are known 10 5 0 −5 −10 −15 10 5 0 −5 −10 −15 ∆ RA (arcsec) ∆ RA (arcsec) Tidal distortion of IRS 3 envelope

7500, 5000 and 2500 years red, blue and black Evolved Stars: ~109 yrs

Sgr A* Evolved Stars: ~109 yrs

Sgr A* IRS 3: 13CO velocity Cube

ç

•Disk mass 0.03-0.06 Msun Millimeter contours over 0.7mm •Size scale ~500AU Radio proplyds have mm counterparts •Minimum Mass Solar Nebula ~ 0.1Msun • Conclusions Sub-mm

q Sensitive radio and mm observations q Large number of protostellar candidates and bipolar CO outflows q Implying ongoing low-mass star formation near Sgr A*