ALMA: status report on construction and early results from commissioning

Hills, R. E.; Kurz, R.; Peck, A. B.

doi:10.1117/12.857017

Cited by 28 publications

(20 citation statements)

References 3 publications

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“…The Atacama Large Millimeter/submillimeter Array (ALMA) is a powerful, general purpose radio telescope designed to address a broad program of forefront astrophysics at millimeter and submillimeter (mm/submm) wavelengths (Wootten and Thompson, 2009;Hills, Kurz, and Peck, 2010). Briefly, ALMA is an interferometric array that will ultimately be comprised of 66 antennas: 50 × 12 m antennas (the 12-m array); 12 × 7 m antennas (the 7-m array); and 4 × 12 m "total power" antennas (the TP array)…”

Section: Introductionmentioning

confidence: 99%

Observing the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA): High-Resolution Interferometric Imaging

et al. 2017

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Observations of the Sun at millimeter and submillimeter wavelengths offer a unique probe into the structure, dynamics, and heating of the chromosphere; the structure of sunspots; the formation and eruption of prominences and filaments; and energetic phenomena such as jets and flares. High-resolution observations of the Sun at millimeter and submillimeter wavelengths are challenging due to the intense, extended, lowcontrast, and dynamic nature of emission from the quiet Sun, and the extremely intense and variable nature of emissions associated with energetic phenomena. The Atacama Large Millimeter/submillimeter Array (ALMA) was designed with solar observations in mind. The requirements for solar observations are significantly different from observations of sidereal sources and special measures are necessary to successfully carry out this type of observations. We describe the commissioning efforts that enable the use of two frequency bands, the 3 mm band (Band 3) and the 1.25 mm band (Band 6), for continuum interferometric-imaging observations of the Sun with ALMA. Examples of high-resolution synthesized images obtained using the newly commissioned modes during the solar commissioning campaign held in December 2015 are presented. Although only 30 of the eventual 66 ALMA antennas were used for the campaign, the solar images synthesized from the ALMA commissioning data reveal new features of the solar atmosphere that demonstrate the potential power of ALMA solar observations. The ongoing expansion of ALMA and solar-commissioning efforts will continue to enable new and unique solar observing capabilities.

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Section: Introductionmentioning

confidence: 99%

Observing the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA): High-Resolution Interferometric Imaging

et al. 2017

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“…The inability to resolve the different structures limits the ability to infer the actual umbral temperature from the observations. The high spatial resolution of the Atacama Large Millimeter/sub-millimeter Array (ALMA: Hills, et al 2010) in the millimeter and sub-millimeter range is sufficient to well-resolve the umbra of a typical sunspot. The purpose of this study is to explore the structure of a sunspot at λ=3 mm in high-resolution ALMA images and to compare it with ultraviolet (UV) and extreme ultraviolet (EUV) images obtained by the Interface Region Imaging Spectrograph (IRIS) and the Solar Dynamics Observatory (SDO).…”

Section: Introductionmentioning

confidence: 99%

ALMA Discovery of Solar Umbral Brightness Enhancement at λ = 3 mm

Iwai

Loukitcheva

Shimojo

et al. 2017

ApJL

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We report the discovery of a brightness enhancement in the center of a large sunspot umbra at a wavelength of 3 mm using the Atacama Large Millimeter/sub-millimeter Array (ALMA). Sunspots are amongst the most prominent features on the solar surface, but many of their aspects are surprisingly poorly understood. We analyzed a λ=3 mm (100 GHz) mosaic image obtained by ALMA, which includes a large sunspot within the active region AR12470 on December 16, 2015. The 3 mm map has a 300"×300" field-of-view and 4".9×2".2 spatial resolution, which is the highest spatial-resolution map of an entire sunspot in this frequency range. We find a gradient of 3 mm brightness from a high value in the outer penumbra to a low value in the inner penumbra/outer umbra. Within the inner umbra, there is a marked increase in 3mm brightness temperature, which we call an umbral brightness enhancement. This enhanced emission corresponds to a temperature excess of 800 K relative to the surrounding inner penumbral region and coincides with excess brightness in the 1330 and 1400 Å slitjaw images of the Interface Region Imaging Spectrograph (IRIS), adjacent to a partial lightbridge. This λ=3 mm brightness enhancement may be an intrinsic feature of the sunspot umbra at chromospheric heights, such as a manifestation of umbral flashes, or it could be related to a coronal plume since the brightness enhancement was coincident with the footpoint of a coronal loop observed at 171 Å.

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“…IRAS 16547−4247 was observed with ALMA (Hills et al 2010) during Early Science Cycle 0 in its extended configuration using the band 7 receivers. The observations were performed in four executions with 32 12 m antennas at an angular resolution of ∼0.…”

Section: Observationsmentioning

confidence: 99%

Iras 16547–4247: A New Candidate of a Protocluster Unveiled With Alma

Higuchi¹,

Saigo²,

Chibueze³

et al. 2014

ApJ

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We present the results of continuum and 12 CO(3-2) and CH 3 OH(7-6) line observations of IRAS 16547−4247 made with the Atacama Large Millimeter/submillimeter Array (ALMA) at an angular resolution of ∼0. 5. The 12 CO(3-2) emission shows two high-velocity outflows whose driving sources are located within the dust continuum peak. The alignment of these outflows does not coincide with that of the wide-angle, large-scale, bipolar outflow detected with the Atacama Pathfinder Experiment in previous studies. The CH 3 OH(7-6) line emission traces an hourglass structure associated with the cavity walls created by the outflow lobes. Taking into account our results together with the position of the H 2 O and class I CH 3 OH maser clusters, we discuss two possible scenarios that can explain the hourglass structure observed in IRAS 16547−4247: (1) precession of a biconical jet, (2) multiple, or at least two, driving sources powering intersecting outflows. Combining the available evidence, namely, the presence of two cross-aligned bipolar outflows and two different H 2 O maser groups, we suggest that IRAS 16547−4247 represents an early formation phase of a protocluster.

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ALMA: status report on construction and early results from commissioning

Cited by 28 publications

References 3 publications

Observing the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA): High-Resolution Interferometric Imaging

Observing the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA): High-Resolution Interferometric Imaging

ALMA Discovery of Solar Umbral Brightness Enhancement at λ = 3 mm

Iras 16547–4247: A New Candidate of a Protocluster Unveiled With Alma

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