The Sun at millimeter wavelengths I. Introduction to ALMA Band 3 observations
Sven Wedemeyer, Mikolaj Szydlarski, Shahin Jafarzadeh, Henrik Eklund, Juan Camilo Guevara Gomez, Tim Bastian, Bernhard Fleck, Jaime de la Cruz Rodriguez, Andrew… 展开作者
Sven Wedemeyer, Mikolaj Szydlarski, Shahin Jafarzadeh, Henrik Eklund, Juan Camilo Guevara Gomez, Tim Bastian, Bernhard Fleck, Jaime de la Cruz Rodriguez, Andrew Rodger, Mats Carlsson
备注：
14 pages, 9 figures; accepted for publication in A&A
We present an initial study of one of the first ALMA Band 3 observations of the Sun with the aim to characterise the diagnostic potential of brightness temperatures measured with ALMA on the Sun. The observation covers 48min at a cadence of 2s targeting a Quiet Sun region at disk-centre. Corresponding time series of brightness temperature maps are constructed with the first version of the Solar ALMA Pipeline (SoAP) and compared to simultaneous SDO observations. The angular resolution of the observations is set by the synthesized beam (1.4x2.1as). The ALMA maps exhibit network patches, internetwork regions and also elongated thin features that are connected to large-scale magnetic loops as confirmed by a comparison with SDO maps. The ALMA Band 3 maps correlate best with the SDO/AIA 171, 131 and 304 channels in that they exhibit network features and, although very weak in the ALMA maps, imprints of large-scale loops. A group of compact magnetic loops is very clearly visible in ALMA Band 3. The brightness temperatures in the loop tops reach values of about 8000-9000K and in extreme moments up to 10 000K. ALMA Band 3 interferometric observations from early observing cycles already reveal temperature differences in the solar chromosphere. The weak imprint of magnetic loops and the correlation with the 171, 131, and 304 SDO channels suggests though that the radiation mapped in ALMA Band 3 might have contributions from a larger range of atmospheric heights than previously assumed but the exact formation height of Band 3 needs to be investigated in more detail. The absolute brightness temperature scale as set by Total Power measurements remains less certain and must be improved in the future. Despite these complications and the limited angular resolution, ALMA Band 3 observations have large potential for quantitative studies of the small-scale structure and dynamics of the solar chromosphere.
The (sub)millimeter radiation of solar flares is poorly understood. Without spatial resolution, it cannot be compared easily to flare emissions in other wavelengths. The Atacama Large Millimeter-submillimeter Array (ALMA) offers sufficient resolution for the first time. However, used as an interferometer, its field of view is smaller than an active region and ALMA cannot observe on demand when a flare occurs. We use readily available large scale single-dish ALMA observations of solar millimeter flares and compare them to well-known features observed in other wavelengths. The properties of thes…
Temporal variation of millimeter lines is a new direction of research for evolved stars. It has the potential to probe the dynamical wind launching processes from time dimension. We report here the first ALMA (Atacama Large Millimeter Array) results that cover 817 days of an on-going monitoring of 1.1 mm lines in the archetypal carbon star IRC +10216. The monitoring is done with the compact 7-m array (ACA) and in infrared with a 1.25 m telescope in Crimea. A high sensitivity of the cumulative spectra covering a total of ~7.2 GHz between 250 - 270 GHz range has allowed us to detect about 148 kn…
We report the results of the Atacama Large Millimeter/sub-millimeter Array (ALMA) observations of the solar chromosphere on the southern polar limb. Coordinated observations with the Interface Region Imaging Spectrograph (IRIS) are also conducted. ALMA provided unprecedented high spatial resolution in the millimeter band ($\approx$ 2.0 arcsec) at 100 GHz frequency with a moderate cadence (20 s). The results are as follows: (1) The ALMA 100 GHz images show saw-tooth patterns on the limb, and a comparison with SDO/AIA 171Å images shows a good correspondence of the limbs with each other. (2) The …
Solar observations with the Atacama Large Millimeter/sub-millimeter Array (ALMA) facilitate studying the atmosphere of the Sun at chromospheric heights at high spatial and temporal resolution at millimeter wavelengths. ALMA intensity data at mm-wavelengths are used for a first detailed systematic assessment of the occurrence and properties of small-scale dynamical features in the quiet Sun. ALMA Band 3 data (~ $3$ mm / $100$ GHz) with spatial resolution ~ $1.4$ - $2.1$ arcsec and a duration of ~ $40$ min are analysed together with SDO/HMI magnetograms. The temporal evolution of the mm-maps is …
The Periastron Passage of T Tauri South B as Viewed by ALMA: Millimeter Flux Variations and Dust Heating Triggered by Orbital Motion
Space Telescope Science Insitute（太空望远镜科学研究所）；Laboratoire d’Astrophysique de Bordeaux, Université de Bordeaux, CNRS（波尔多大学天体物理学实验室，法国国家科学研究中心）；The CHARA Array of Georgia State University（佐治亚州立大学CHARA阵列）；The Institut de Radioastronomie Millimétrique (IRAM)（毫米射电天文研究所）
In the past few years, the ALMA radio telescope has become available for solar observations. ALMA diagnostics of the solar atmosphere are of high interest because of the theoretically expected linear relationship between the brightness temperature at mm wavelengths and the local gas temperature in the solar atmosphere. Key for the interpretation of solar ALMA observations is understanding where in the solar atmosphere the ALMA emission originates. Recent theoretical studies have suggested that ALMA bands at 1.2 (band 6) and 3 mm (band 3) form in the middle and upper chromosphere at significant…
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of a quiet-Sun region at a wavelength of 3 mm, obtained during the first solar ALMA cycle on April 27, 2017, and compare them with available chromospheric observations in the UV and visible as well as with photospheric magnetograms. ALMA images clearly reveal the presence of distinct particularly dark/cool areas in the millimeter maps having temperatures as low as 60% of the normal quiet Sun at 3 mm, which are not seen in the other data. We speculate that ALMA is sensing cool chromospheric gas, whose presence had earli…
Millimeter and sub-millimeter observations have made fundamental contributions to our current understanding of the transition from AGB stars to white dwarfs. The approaching era of ALMA brings significantly enhanced observing capabilities at these wavelengths and promises to push back the frontiers in a number of ways. We examine the scientific prospects of this new era for PNe, with an emphasis on how developments may contribute to the goals of the asymmetric PNe community.
The Atacama Large Millimeter-Submillimeter Array (ALMA) has opened a new window for studying the Sun via high-resolution high-sensitivity imaging at millimeter wavelengths. In this contribution I review the capabilities of the instrument for solar observing and describe the extensive effort taken to bring the possibility of solar observing with ALMA to the scientific community. The first solar ALMA observations were carried out during 2014 and 2015 in two ALMA bands, Band 3 (3 mm) and Band 6 (1.3 mm), in single-dish and interferometric modes, using single pointing and mosaicing observing techn…
Aims. The main aim of the present analysis is to decipher (i) the small-scale bright features in solar images of the quiet Sun and active regions obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) and (ii) the ALMA correspondence of various known chromospheric structures visible in the H-alpha images of the Sun. Methods. Small-scale ALMA bright features in the quiet Sun region were analyzed using single-dish ALMA observations (1.21 mm, 248 GHz) and in an active region using interferometric ALMA measurements (3 mm, 100 GHz). With the single-dish observations, a full-disk sola…
The well-studied M9 dwarf TVLM 513-46546 is a rapid rotator (P_rot ~ 2 hr) hosting a stable, dipolar magnetic field of ~3 kG surface strength. Here we report its detection with ALMA at 95 GHz at a mean flux density of $56 \pm 12$ uJy, making it the first ultracool dwarf detected in the millimeter band, excluding young, disk-bearing objects. We also report flux density measurements from unpublished archival VLA data and new optical monitoring data from the Liverpool Telescope. The ALMA data are consistent with a power-law radio spectrum that extends continuously between centimeter and millimete…
We have carried out high resolution observations with Atacama Large Millimeter/Submillimeter Array (ALMA) of continuum emission from Orion KL region. We identify 11 compact sources at ALMA band 6 (245 GHz) and band 7 (339 GHz), including Hot Core, Compact Ridge, SMA1, IRc4, IRc7, and a radio source I (Source I). Spectral energy distribution (SED) of each source is determined by using previous 3 mm continuum emission data. Physical properties such as size, mass, hydrogen number density and column density are discussed based on the dust graybody SED. Among 11 identified sources, Source I, a mass…
The Atacama Large Millimeter/submillimeter Array (ALMA) will be a valuable tool for observing the chromosphere of our Sun at (sub-)millimeter wavelengths at high spatial, temporal and spectral resolution and as such has great potential to address long-standing scientific questions in solar physics. In order to make the best use of this scientific opportunity, the Solar Simulations for the Atacama Large Millimeter Observatory Network has been initiated. A key goal of this international collaboration is to support the preparation and interpretation of future observations of the Sun with ALMA.
The Solar Simulations for the Atacama Large Millimeter Observatory Network (SSALMON) was initiated in 2014 in connection with two ALMA development studies. The Atacama Large Millimeter/submillimeter Array (ALMA) is a powerful new tool, which can also observe the Sun at high spatial, temporal, and spectral resolution. The international SSALMONetwork aims at coordinating the further development of solar observing modes for ALMA and at promoting scientific opportunities for solar physics with particular focus on numerical simulations, which can provide important constraints for the observing mode…
We present the first high-resolution Atacama Large Millimeter/Submillimeter Array (ALMA) observations of a sunspot at wavelengths of 1.3 mm and 3 mm, obtained during the solar ALMA Science Verification campaign in 2015, and compare them with the predictions of semi-empirical sunspot umbral/penumbral atmosphere models. For the first time millimeter observations of sunspots have resolved umbral/penumbral brightness structure at the chromospheric heights, where the emission at these wavelengths is formed. We find that the sunspot umbra exhibits a radically different appearance at 1.3 mm and 3 mm,…
ALMA will open a new chapter in the study of the Sun by providing a leap in spatial resolution and sensitivity compared to currently available mm wave- length observations. In preparation of ALMA, we have carried out a large number of observational tests and state-of-the-art radiation MHD simulations. Here we review the best available observations of the Sun at millimeter wavelengths.Using state of the art radiation MHD simulations of the solar atmosphere we demonstrate the huge potential of ALMA observations for uncovering the nature of the solar chromosphere. We show that ALMA will not only …
We report the detection of three large millimeter flaring events from the nearby Sun-like, $ε$ Eridani, found in archival ALMA 12m and ACA observations at 1.33 mm taken from 2015 January 17-18 and 2016 October 24-November 23, respectively. This is the first time that flares have been detected from a Sun-like star at millimeter wavelengths. The largest flare among our data was detected in the ALMA observations on 2015 January 17 from 20:09:10.4-21:02:49.3 (UTC) with a peak flux density of 28 $\pm$ 7 mJy and a duration of 9 sec. The peak brightness of the largest flare is $ 3.4 \pm 0.9 \times 10…
The Atacama Large Millimeter/submillimeter Array (ALMA) is a new powerful tool for observing the Sun at high spatial, temporal, and spectral resolution. These capabilities can address a broad range of fundamental scientific questions in solar physics. The radiation observed by ALMA originates mostly from the chromosphere - a complex and dynamic region between the photosphere and corona, which plays a crucial role in the transport of energy and matter and, ultimately, the heating of the outer layers of the solar atmosphere. Based on first solar test observations, strategies for regular solar ca…
Solar observations at sub-mm, mm and cm wavelengths offer a straightforward diagnostic of physical conditions in the solar atmosphere because they yield measurement of brightness temperature which, for optically thick features, equals intrinsic temperature - much unlike solar diagnostics in other spectral ranges. The Atacama Large Millimeter and sub-millimeter Array (ALMA) has therefore opened a new, hitherto underexplored, spectral window for studying the enigmatic solar chromosphere. In this review we discuss initial ALMA studies of the quiet chromosphere that used both single-dish and compa…
Context: WISE J085510.83-071442.5 (W0855) is a unique object: with Teff ca. 250 K, it is the coldest known brown dwarf (BD), located at only ca.2.2 pc form the Sun. It is extremely faint, which makes any astronomical observations difficult. However, at least one remotely similar ultra-low-mass object, the M9 dwarf TVLM 513-46546, has been shown to be a steady radio emitter at frequencies up to 95 GHz with superimposed active states where strong, pulsed emission is observed. Aims: Our goal is to determine the millimeter radio properties of W0855 with deep observations around 93 GHz (3.2 mm) in …
Various solar features can be seen on maps of the Sun in the mm and sub-mm wavelength range. The recently installed Atacama Large Millimeter/submillimeter Array (ALMA) is capable of observing the Sun in that wavelength range with an unprecedented spatial, temporal and spectral resolution. To interpret solar observations with ALMA the first important step is to compare ALMA maps with simultaneous images of the Sun recorded in other spectral ranges. First we identify different structures in the solar atmosphere seen in the optical, IR and EUV parts of the spectrum (quiet Sun (QS), active regions…
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, low- contrast, 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 Milli…
We present new measurements of the millimeter wavelength continuum emission from the long period variable Mira ($o$ Ceti) at frequencies of 46 GHz, 96 GHz, and 229 GHz ($λ$~7 mm, 3 mm, and 1 mm) based on observations obtained with the Jansky Very Large Array (JVLA) and the Atacama Large Millimeter/submillimeter Array (ALMA). The measured millimeter flux densities are consistent with a radio photosphere model derived from previous observations, where flux density, $S_ν\proptoν^{1.86}$. The stellar disk is resolved, and the measurements indicate a decrease in the size of the radio photosphere at…
Identification of the mechanisms responsible for heating the solar chromosphere and corona remains an outstanding problem, one of great relevance to late-type stars as well. There has been tremendous progress in the past decade, largely driven by new instruments, new observations, and sophisticated modeling efforts. Despite this progress, gaps remain. We briefly discuss the need for radio coverage of the 3D solar atmosphere and discuss the requirements.
Images of the Sun at millimeter wavelengths obtained by ALMA show a significant correspondence with the magnetograms. In this paper, we investigate this correspondence by comparing ALMA full-disk solar image taken at 1.2 mm with a SDO/HMI magnetogram and analyze their correlation. It is found that chromospheric network and active regions show a positive correlation where brightness temperature is increasing with the line-of-sight magnetic field strength, while sunspots have a negative correlation. Quiet Sun regions do not show any dependence of the brightness temperature with the magnetic fiel…
Using Atacama Large Millimeter/submillimeter Array (ALMA) observations of the quiet Sun at 1.26 and 3 mm, we study spatially resolved oscillations and transient brightenings, i.e. small, weak events of energy release. Both phenomena may have a bearing on the heating of the chromosphere. At 1.26 mm, in addition to power spectra of the original data, we degraded the images to the spatial resolution of the 3 mm images and used fields of view of equal area for both data sets. The detection of transient brightenings was made after the oscillations were removed. At both frequencies we detected p-mod…
Debris disks can be seen as the left-overs of giant planet formation and the possible nurseries of rocky planets. While M-type stars out-number more massive stars we know very little about the time evolution of their circumstellar disks at ages older than $\sim 10$\,Myr. Sub-millimeter observations are best to provide first order estimates of the available mass reservoir and thus better constrain the evolution of such disks. Here, we present ALMA Cycle\,3 Band\,7 observations of the debris disk around the M2 star TWA\,7, which had been postulated to harbor two spatially separated dust belts, b…
The Atacama Large Millimeter/submillimeter Array offers an unprecedented view of our Sun at sub-/millimeter wavelengths. The high spatial, temporal, and spectral resolution facilitates the measurement of gas temperatures and magnetic fields in the solar chromosphere with high precision. The anticipated results will revolutionize our understanding of the solar atmosphere and may in particular result in major steps towards solving the coronal heating problem. Based on state-of-the-art 3D radiation magnetohydrodynamic simulations, we calculate the emergent continuum intensity (and thus brightness…
Interferometric observations of the Sun with ALMA provide valuable diagnostic tools for studying the small-scale dynamics of the solar atmosphere. Estimations of the observability of the small-scale dynamics as a function of spatial resolution for regions with different characteristic magnetic field topology facilitate a more robust analysis of ALMA observations of the Sun. A 3D model of the solar atmosphere from the MHD code Bifrost was used to produce high-cadence observables at mm and submm wavelengths. The synthetic observables for receiver bands 3-10 were degraded to the angular resolutio…
We present millimeter, optical, and soft X-ray observations of a stellar flare with an energy squarely in the regime of typical X1 solar flares. The flare was observed from Proxima Cen on 2019 May 6 as part of a larger multi-wavelength flare monitoring campaign and was captured by Chandra, LCOGT, du Pont, and ALMA. Millimeter emission appears to be a common occurrence in small stellar flares that had gone undetected until recently, making it difficult to interpret these events within the current multi-wavelength picture of the flaring process. The May 6 event is the smallest stellar millimeter…
We present observations of a solar plage in the millimeter-continuum with the ALMA and in the Ca 8542 and Na 5896 spectral lines with the Interferometric BIdimensional Spectrometer (IBIS). Our goal is to compare the measurement of local gas temperatures provided by ALMA with the temperature diagnostics provided by non-LTE inversions using STIC. In performing these inversions, we find that using column mass as the reference height scale, rather than optical depth, provides more reliable atmospheric profiles above the temperature minimum and that the treatment of non- LTE hydrogen ionization bri…
The aim of this study is to demonstrate how the logarithmic millimeter continuum gradient observed using the Atacama Large Millimeter/submillimeter Array (ALMA) may be used to estimate optical thickness in the solar atmosphere. We discuss how using multi-wavelength millimeter measurements can refine plasma analysis through knowledge of the absorption mechanisms. Here we use sub-band observations from the publicly available science verification (SV) data, whilst our methodology will also be applicable to regular ALMA data. The spectral resolving capacity of ALMA SV data is tested using the enha…
We present an overview of high resolution quiet Sun observations, from disk center to the limb, obtained with the Atacama Large mm and sub-mm Array (ALMA) at 3 mm. Seven quiet Sun regions were observed with resolution of up to 2.5" by 4.5". We produced both average and snapshot images by self-calibrating the ALMA visibilities and combining the interferometric images with full disk solar images. The images show well the chromospheric network, which, based on the unique segregation method we used, is brighter than the average over the fields of view of the observed regions by $\sim 305$ K while …
Millimeter emission from debris disks around stars of different ages provides constraints on the collisional evolution of planetesimals. We present ALMA 1.3 millimeter observations of a sample of 76 Solar-type stars in the ~115 Myr old Pleiades star cluster. These ALMA observations complement previous infrared observations of this sample by providing sensitivity to emission from circumstellar dust at lower temperatures, corresponding to debris at radii comparable to the Kuiper Belt and beyond. The observations obtain a beam size of 1.5 arcsec (200 au) and a median rms noise of 54 mircoJy/beam,…
Modeling brightness temperature of sunspots using ALMA single-dish observations
Hvar Observatory, Faculty of Geodesy, University of Zagreb（萨格勒布大学测量学学院哈弗尔天文台）；Landessternwarte, Zentrum für Astronomie der Universität Heidelberg（海德堡大学天文学中心州立天文台）；University of Applied Sciences and Arts Northwestern Switzerland（瑞士西北应用科学与艺术大学）；NAT - Núcleo de Astrofísica, Universidade Cidade de São Paulo（圣保罗城市大学天体物理核心）；Center for Solar-Terrestrial Research, New Jersey Institute of Technology（新泽西理工学院太阳-地球研究数据中心）；Protostar Labs d.o.o.（原恒星实验室有限责任公司）；Institute of Physics, University of Graz（格拉茨大学物理研究所）
The brightness temperature of the radio free-free emission at millimeter range is an effective tool for characterizing the vertical structure of the solar chromosphere. In this paper, we report on the first single-dish observation of a sunspot at 85 and 115 GHz with sufficient spatial resolution for resolving the sunspot umbra using the Nobeyama 45 m telescope. We used radio attenuation material, i.e. a solar filter, to prevent the saturation of the receivers. Considering the contamination from the plage by the side-lobes, we found that the brightness temperature of the umbra should be lower t…
ALMA observations of the Sun at mm-$λ$ offer a unique opportunity to investigate the temperature structure of the solar chromosphere. In this article we expand our previous work on modeling the chromospheric temperature of the quiet Sun, by including measurements of the brightness temperature in the network and cell interiors, from high resolution ALMA images at 3 mm (Band 3) and 1.26 mm (Band 6). We also examine the absolute calibration of ALMA full-disk images. We suggest that the brightness temperature at the center of the solar disk in Band 6 is $\sim440$ K above the value recommended by W…
The Atacama Large Millimeter-submillimeter Array (ALMA), sited on the high desert plains of Chajnantor in Chile, has opened a new window onto solar physics in 2016 by providing continuum observations at millimeter and sub-millimeter wavelengths with an angular resolution comparable to that available at optical (O), ultraviolet (UV), extreme ultraviolet (EUV), and X-ray wavelengths, and with superior time resolution. In the intervening years, progress has been made testing and commissioning new observing modes and capabilities, in developing data calibration strategies, and in data imaging and …
The Atacama Large Millimeter/submillimeter Array (ALMA) offers new diagnostic possibilities that complement other commonly used diagnostics for the study of our Sun. In particular, ALMA's ability to serve as an essentially linear thermometer of the chromospheric gas at unprecedented spatial resolution at millimetre wavelengths and future polarisation measurements have great diagnostic potential. Solar ALMA observations are therefore expected to contribute significantly to answering long-standing questions about the structure, dynamics and energy balance of the outer layers of the solar atmosph…
Aims: The aim of this paper is to demonstrate that millimeter wave data can be used to distinguish between various atmospheric models of sunspots, whose temperature structure in the upper photosphere and chromosphere has been the source of some controversy. Methods: We use observations of the temperature contrast (relative to the quiet Sun) above a sunspot umbra at 3.5 mm obtained with the Berkeley-Illinois-Maryland Array (BIMA), complemented by submm observations from Lindsey & Kopp (1995) and 2 cm observations with the Very Large Array. These are compared with the umbral contrast calculated …
We present 1.3 millimeter ALMA Cycle 0 observations of the edge-on debris disk around the nearby, ~10 Myr-old, M-type star AU Mic. These observations obtain 0.6 arcsec (6 AU) resolution and reveal two distinct emission components: (1) the previously known dust belt that extends to a radius of 40 AU, and (2) a newly recognized central peak that remains unresolved. The cold dust belt of mass about 1 lunar mass is resolved in the radial direction with a rising emission profile that peaks sharply at the location of the outer edge of the "birth ring" of planetesimals hypothesized to explain the mid…
The precise mechanisms that provide the non-radiative energy for heating the chromosphere and the corona of the Sun and other stars are at the focus of intense contemporary research. Observations at submm/mm wavelengths are particularly useful to obtain information about the run of the temperature in the upper atmosphere of Sun-like stars. We used ALMA to study the chromospheric emission of the aCen binary system in all six available frequency bands during Cycle2 in 2014/15. Since ALMA is an interferometer, the multi-telescope array is particularly suited for the observation of point sources. …
We present joint observations of the Sun by the Atacama Large Millimeter/submillimeter Array (ALMA) and the Interface Region Imaging Spectrograph (IRIS). The observations were made of a solar active region on 2015 December 18 as part of the ALMA science verification effort. A map of the Sun's continuum emission of size $2.4' \times 2.3'$ was obtained by ALMA at a wavelength of 1.25 mm (239 GHz) using mosaicing techniques. A contemporaneous map of size $1.9'\times 2.9'$ was obtained in the Mg II h doublet line at 2803.5Å by IRIS. Both mm/submm$-λ$ continuum emission and ultraviolet (UV) line em…
We measured the center-to-limb variation of the brightness temperature, $T_b$, from ALMA full-disk images at two frequencies and inverted the solution of the transfer equation to obtain the electron temperature, $T_e$ as a function of optical depth, $τ$. The ALMA images are very similar to AIA images at 1600Å. The brightness temperature at the center of the disk is 6180 and 7250 K at 239 and 100 GHz respectively, with dispersions of 100 and 170 K. Plage regions stand out clearly in the 239/100 GHz intensity ratio, while faculae and filament lanes do not. The solar disk radius, reduced to 1 AU,…
We present a statistical analysis of power distribution of oscillations in a plage region in active region NOAA AR12651, observed jointly with ALMA (Atacama Large Millimeter/Submillimeter Array), IRIS (Interface Region Imaging Spectrograph), and SDO (Solar Dynamics Observatory). We employ coordinated ALMA Band-6 (1.25 mm) brightness temperature maps, IRIS Slit-Jaw Images in 2796 Å passband, and observations in six passbands (1600 Å, 304 Å, 131 Å, 171 Å, 193 Å and 211 Å) of AIA (Atmospheric Imaging Assembly) onboard SDO. We perform Lomb-Scargle transforms to study the distribution of oscillatio…
The Atacama Large Millimeter-submillimeter Array (ALMA) radio telescope has commenced science observations of the Sun starting in late 2016. Since the Sun is much larger than the field of view of individual ALMA dishes, the ALMA interferometer is unable to measure the background level of solar emission when observing the solar disk. The absolute temperature scale is a critical measurement for much of ALMA solar science, including the understanding of energy transfer through the solar atmosphere, the properties of prominences, and the study of shock heating in the chromosphere. In order to prov…
The disk around the Herbig Ae/Be star HD 100546 has been extensively studied and it is one of the systems for which there are observational indications of ongoing and/or recent planet formation. However, up until now no resolved image of the millimeter dust emission or the gas has been published. We present the first resolved images of the disk around HD 100546 obtained in Band 7 with the ALMA observatory. The CO (3-2) image reveals a gas disk that extends out to 350 au radius at the 3-sigma level. Surprisingly, the 870um dust continuum emission is compact (radius <60 au) and asymmetric. The d…
The intensity of radiation at millimeter wavelengths from the solar atmosphere is closely related to the plasma temperature and the height of formation of the radiation is wavelength dependent. From that follows that the slope of the brightness temperature (T$_\mathrm{b}$) continuum, samples the local gradient of the gas temperature of the sampled layers in the solar atmosphere. We use solar observations from the Atacama Large Millimeter/sub-millimeter Array (ALMA) and perform estimations and prediction of the slope of the T$_\mathrm{b}$ continuum based on differences between synthetic observa…
In this paper, we analyse the upper limit fluxes of sub-millimeter ortho-H$_{2}$$^{16}$O 321 GHz, para-H$_{2}$$^{18}$O 322 GHz, and HDO 335 GHz lines from the protoplanetary disk around the Herbig Ae star HD 163296, using the Atacama Large Millimeter/Submillimeter Array (ALMA). These water lines are considered to be the best candidate sub-millimeter lines to locate the position of the H$_{2}$O snowline, on the basis of our previous model calculations. We compare the upper limit fluxes with the values calculated by our models with dust emission included, and we constrain the line emitting regio…
IRS 7 is an M red supergiant star which is located at $5".5$ north of Sagittarius A$^\ast$. We detected firstly the continuum emission at 340 GHz of IRS 7 using ALMA. The total flux density of IRS 7 is $S_ν=448\pm45 μ$Jy. The flux density indicates that IRS 7 has a photosphere radius of $R=1170\pm60 ~R_\odot$, which is roughly consistent with the previous VLTI measurement. We also detected a shell like feature with north extension in the H30$α$ recombination line by ALMA. The electron temperature and electron density of the shell like structure are estimated to be $\bar{T}^\ast_{\mathrm e}=465…
We present the first full-disk solar images obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) in Band 7 (0.86 mm; 347 GHz). In spite of the low spatial resolution (21"), several interesting results were obtained. During our observation, the sun was practically devoid of active regions. Quiet Sun structures on the disk are similar to those in Atmospheric Imaging Assembly (AIA) images at 1600 A and 304 A, after the latter are smoothed to the ALMA resolution, as noted previously for Band 6 (1.26 mm) and Band 3 (3 mm) images; they are also similar to negative H$α$ images of equ…
We present ALMA 1.3 mm (230 GHz) observations of the HD 32297 and HD 61005 debris disks, two of the most iconic debris disks due to their dramatic swept-back wings seen in scattered light images. These observations achieve sensitivities of 14 and 13 $μ$Jy beam$^{-1}$ for HD 32297 and HD 61005, respectively, and provide the highest resolution images of these two systems at millimeter wavelengths to date. By adopting a MCMC modeling approach, we determine that both disks are best described by a two-component model consisting of a broad ($ΔR/R> 0.4$) planetesimal belt with a rising surface densit…
This document was created by the Solar Simulations for the Atacama Large Millimeter Observatory Network (SSALMON) in preparation of the first regular observations of the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA), which are anticipated to start in ALMA Cycle 4 in October 2016. The science cases presented here demonstrate that a large number of scientifically highly interesting observations could be made already with the still limited solar observing modes foreseen for Cycle 4 and that ALMA has the potential to make important contributions to answering long-standing scient…
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 field-of-view and spatial resolution, which is the highest spatial-resolution map of an entire sunspot in this frequency …
We investigate the upper chromosphere and the transition region of the sunspot umbra using the radio brightness temperature at 34 GHz (corresponding to 8.8-mm observations) as observed by the Nobeyama Radioheliograph (NoRH). Radio free-free emission in the longer millimeter range is generated around the transition region, and its brightness temperature yields the region's temperature and density distribution. We use the NoRH data at 34 GHz by applying the Steer-CLEAN image synthesis. These data and the analysis method enable us to investigate the chromospheric structures in the longer millimet…
Aims. We use advanced 3D NLTE radiative magnetohydrodynamic simulations of the solar atmosphere to carry out detailed tests of chromospheric diagnostics at millimeter and submillimeter wavelengths. Methods. We focused on the diagnostics of the thermal structure of the chromosphere in the wavelength bands from 0.4 mm up to 9.6 mm that can be accessed with the Atacama Large Millimeter/Submillimeter Array (ALMA) and investigated how these diagnostics are affected by the instrumental resolution. Results. We find that the formation height range of the millimeter radiation depends on the location in…
Observations by the Atacama Large Millimeter/sub-millimeter Array of the dust continuum and $^{13}$CO(3-2) millimeter emissions of the triple stellar system GG Tau A are analysed, giving evidence for a rotating gas disc and a concentric and coplanar dust ring. The present work complements an earlier analysis (Tang et al. 2016) by exploring detailed properties of the gas disc. A 95% confidence level upper limit of 0.24 arcsec (34 au) is placed on the disc scale height at a distance of 1 arcsec (140 au) from the central stars. Evidence for Keplerian rotation of the gas disc is presented, the rot…
