Atacama Large Millimeter/submillimeter Array

Karl G. Jansky Very Large ArrayRobert C. Byrd Green Bank Telescope

Very Long Baseline Array

ALMA Science HighlightsApril 10, 2014

Science Highlights

ALMADisrupting comets in β Pic

• Protoplanetary disks of dusty debris around young stars are formed by collisions of asteroids, comets and dwarf planets.

• ALMA observations of the archetypal debris disk around β Pictoris show that 0.3% of a Moon mass of CO orbits in its debris belt. The gas distribution is highly asymmetric, with 30% found in a single clump 85 AU from the star, in a plane closely aligned with the orbit of the inner planet, β Pic b.

• CO will dissociate in 100 yrs so close to the star, implying active CO deposition in the disk. This gas clump likely delineates a region of enhanced cometary collisions, either from a mean motion resonance with an unseen giant planet, or from the remnants of a collision of icy Mars-mass planets.

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ALMA image of the dust continuum, and CO emission (observed and deprojected) from β Pic (Dent et al. 2014)

ALMAHot Stars evaporate PP Disks in Orion

• ALMA has imaged the submm thermal continuum emission from a large sample of protoplanetary disks in Orion, known as proplyds, seen in HST images as dusty shadows or reflected light.

• ALMA detects most of these systems, with implied dust masses from 0.3 to 79 Mjup

• An anti-correlation is seen between regions of the most intense UV interstellar radiation field and the existence of massive PP disks, indicating the extreme impact O stars have on their local environments.

• These results suggest that a rapid dissipation of disk masses likely inhibits potential planet formation in the extreme-UV-dominated regions of OB associations.

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ALMA and HST images of proplyds in Orion: large and small scales (Mann et al. 2014)

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ALMA Observations Give New Insights into ProtostarsCO emission from the outflow in HH46/47 imaged by ALMA has revealed ultrafast gas, depositing energy and momentum into the nearby medium.

ALMA Science Results

• In this ALMA image, blue colors show gas approaching us from HH46/47 and red shows receding gas.

• The outflow shows both broad and collimated components; near the source velocities reach >30 km s-1

• Discontinuities suggest episodic bursts on 100 yr timescales

Arce, Mardones, Corder et al. 2013 ApJ 774, 39

ESO/ALMA (ESO/NAOJ/NRAO)/ H. Arce

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ALMA Images ‘Dust Trap’ Around Distant Star

• IRS 48 dust and gas observations.The inclined disk around IRS 48 as observed with ALMA 0.44mm observations, centered on the star (white star symbol). – A: ALMA observations, dashed ellipse shows a

63AU radius circle.– B: Integrated CO J=6-5 emission showing

symmetric gas disk with Keplerian rotation (i=50o)

– C: VLT VISIR image at 18.7μm• Proposed mechanism creates a dust trap in the disk of IRS

48: – A massive planet creates an annular gap in the gas disk.– A high-pressure vortex forms at the gap edge, collecting

and trapping millimeter-sized dust particles that would otherwise spiral rapidly inward through the disk.

ALMA Science ResultsVan der Marel, van Dishoeck, Bruderer, et al. Science 340,1199

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ALMA and SMA images of dust, CO and N2H+ emission toward TW Hya. The red circle is the CO snow line prediction.

Imaging of the CO Snow Line in a Solar Nebula AnalogALMA has imaged the CO ‘snow line’ around TW Hya, an analog of the solar nebula. Planets form in the disks around young stars. Their formation efficiency and composition are intimately linked to the protoplanetary disk locations of "snow lines" of abundant volatiles. The chemical imaging used high spatial and spectral resolution observations of N2H+, a reactive ion present in large abundance only where CO is frozen out. The N2H+ emission is distributed in a large ring, with an inner radius that matches CO snow line model predictions. The extracted CO snow line radius of ~ 30 AU is a key parameter in constraining models of the formation dynamics of planetary systems.

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ALMA Observation of the CO-Snowline RingHD163296• HD163296: 122 pc Ae star, 4Myr old, ~0.08Msun disk

• Luminous: snowline distant from star. Massive: high column of gas– Qi et al (2011): Snowline at 155 AU; T~19K from 13CO

SMA data– Mathews et al (2013): DCO+ with ALMA directly images

snowline.• DCO+ limited by CO freezeout, T-dependent D

enhancement

ALMA Science Results

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Imaging a galaxy-scale molecular outflowALMA has imaged expanding molecular shells in the starburst nucleus of NGC 253 at 50-parsec resolution. The extraplanar molecular gas closely tracks the Hα filaments, and connects to expanding molecular shells located in the starburst region. The molecular outflow rate is 9 Mo/yr, implying a ratio of mass-outflow rate to star-formation rate of about 3, indicating that the starburst-driven wind limits the star-formation activity and the final stellar content. These observations support the idea that the growth of large galaxies may be limited by strong wind-driven outflows.

Blue and magenta contours are CO emission at +/- 100 km/s around the nucleus of NGC 253 (Bollato ea. 2013)

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ALMA Reveals Dust Production and Particle Acceleration in Supernova 1987A

• ALMA has produced resolved images at 0.45mm to 3 mm, of the nearest and most recent supernova since the invention of the telescope (Indebetouw et al. 2014)

• Emission from the largest mass of dust measured in a supernova remnant (>0.2 Msun) dominates at shorter wavelengths (to 0.45mm) while synchrotron radiation from shock-accelerated particles dominates emission at longer wavelengths (3mm)

• ALMA images show the dust has formed in the inner ejecta (the cold remnants of the exploded star's core). The extent corresponds well to CO and SiO emission imaged previously by ALMA expanding at 1250 km/s (Kamenetzky et al 2013). ALMA's high resolution demonstrates that the dust emission is concentrated to the center of the remnant, a region not yet affected by the shocks.

• If SN 1987A is typical, supernovae are important cosmological dust producers.

Left: ALMA data in Red shows newly formed dust. Hubble data (green) and Chandra data (blue) show the expanding supernova shock wave. (R. Indebetouw et. al, ) Right: Artists illustration shows the cold inner region of the supernova’s remnants. The outer regions are where the ejected gas are colliding with the gas ejected from the star before its supernova detonation.

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ALMA Open a Powerful New Window into Supernova Ejecta• ALMA’s unprecedented

sensitivity and resolution identify CO in the SN87A inner ejecta. SiO is also seen.

• The C/O clumps in SN1987A contain at least 0. 01 M⊙ of 12 CO, an order of magnitude greater than measured in the first few years after the explosion: 12CO has continued to form over the past 25 years.

• ALMA views the full velocity range of emission, unobscured by dust. Doppler tomography will be possible in CO and other molecules (SiO) to probe the spatial, chemical and kinetic environment within the inner ejecta.

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Kamenetzk, McCray, Indebetouw et al ApJ, in press

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ALMA Reveals Feeding of a Seyfert 1 Nucleus

• ALMA imaging on 25pc scales of the dense nuclear molecular gas disk in NGC 1566 reveals an open arm nuclear spiral seen in CO, HCN and HCO+, in regions obscured in HST images

• Molecular gas shows rotation, and no nuclear outflow

– Between 200pc and 300pc in the disk, the gas loses half its angular momentum in a rotation period implying gravitational torques drive AGN fueling

– Dynamical friction drives the gas to the nucleus in ~1 Myr

– The supermassive black hole is influencing gas dynamics, reversing the gravity torque, driving gas to the nucleus, perhaps fueling the AGN

• First example of trailing molecular arm spiral within the inner Lindblad resonance ring of a bar

Combes et al (2014) Velocity field (top) and integrated intensity (bottom) of the CO(3-2) emission in the center of NGC 1566.

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ALMA images molecular gas dynamics in a nearby AGN/starburst• The Seyfert 2 galaxy NGC 1433 was imaged with ALMA in CO 3-2 at the

unprecedented spatial resolution of 0.''5 = 24 pc.• ALMA reveals a nuclear bar of 400 pc radius embedded in the large-scale

primary bar. The CO map also reveals a nuclear gaseous spiral structure, inside the nuclear ring encircling the nuclear stellar bar.

• Most of the gas show ordered rotation, although a strong (200 km/s, 7 Mo/yr) outflow is seen in the nucleus, likely driven by the inner radio jets, possibly boosted by star formation.

ALMA and HST images of the central parts of the nearby active galaxy NGC 1433. The dim blue background image, showing the central dust lanes of this galaxy (HST). The red colored structures show the ALMA observations of dust and molecular gas (Combes ea).

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ALMA Reveals Ghostly Shape of ‘Coldest Place in the Universe’ • The pre-planetary nebula, the Boomerang Nebula, is the coldest known place in

the Universe, refrigerated by an expanding molecular outflow (Joule-Thomson effect), to roughly 1K. Planetary nebula correspond to the dying moments of Solar-analog stars, the transition from AGB to PN stages.

• HST shows a classic double-lobed ‘hour-glass’ shape with a very narrow central region, expected for expanding gas outflows.

• ALMA CO observations show the inner double structure, but also a more spherical, high velocity outflow on large scales, and a central dust-lane of mm-sized grains. The HST image is most like the result of illumination of the cold outflow material.

The Boomerang Nebula image with ALMA. Blue: HST, shows a classic double-lobe shape with a very narrow central region. ALMA shows a more extended CO distribution, plus a narrow dust lane in the center (Sahai et al).