Maryam Saberi

• Gorai, P.; Saberi, M.; Khouri, T. & Danilovich, T. (2025). Probing sulphur chemistry in oxygen-rich asymptotic giant branch stars with ALMA. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 704. doi: 10.1051/0004-6361/202555994. Fulltekst i vitenarkiv Vis sammendrag

  Context. Sulphur and its isotopic ratios play a crucial role in our understanding of the physical properties of astrophysical environments; in particular, providing key insights into nucleosynthesis, interstellar medium processes, star formation, planetary system evolution, and galactic chemical evolution. Aims. We aim to investigate the distribution of sulphur species - SO 2 , 34 SO 2 , SO, and 34 SO - towards a sample of five oxygen-rich asymptotic giant branch (AGB) stars, along with measurements of excitation temperature, column density, and isotopic ratios. Methods. We used ALMA Band 6, 7, and 8 data of o Ceti, R Dor, W Hya, R Leo, and EP Aqr. SO 2 , 34 SO 2 , SO, and 34 SO were detected towards AGB stars using the CASSIS software. To estimate the gas temperature and column density of these species, we applied the rotational diagram method (when applicable) and the Markov chain Monte Carlo method, assuming local thermodynamic equilibrium (LTE). Finally, line imaging of different transitions was performed to infer the distributions of the detected sulphur-bearing species in our sample. Results. The measured excitation temperatures of SO 2 for our sample sources range from ∼200 to 600 K, with estimated column densities in the range of 1-7 × 10 16 cm −2 . The excitation temperatures estimated using 34 SO 2 are comparable or slightly lower, while the column densities are about an order of magnitude lower than those of SO 2 . Our measured 32 S/ 34 S ratios for R Dor and W Hya are close to the solar value; however, the measured value for o Ceti is slightly higher, and the measured values for EP Aqr and R Leo are lower. Finally, spatial analysis shows that most detected lines appear as centralized emissions. Moreover, the high excitation transitions of SO 2 show compact emission and probe hot gas of the inner region circumstellar envelopes (CSEs), whereas low-excitation transitions trace slightly extended structures. However, we find some differences in the emission of detected species across our sample. Conclusions. The excitation temperature of the observed regions of the CSE can be probed using the SO 2 molecule. The morphological correlation between SO and SO 2 emissions suggests that they are chemically linked. Differences in the emission distributions of the detected species across our sample of low mass-loss rate AGB stars such as (i) centralized emission towards o Ceti with irregular emission shapes, (ii) centralized emission with ordered circular features towards R Leo and W Hya, (iii) clumpy emission features in R Dor, and (iv) unresolved emission in Ep Aqr may arise from several factors, i.e. the physical conditions of the sources (e.g. density and temperature structures of the CSEs), source multiplicity, outflows, rotation, or other associated physical processes such as thermal and nonthermal desorption, the effects of UV photons and cosmic rays, and finally the resolution of our observations. Nonetheless, the predominantly centralized distributions of SO and SO 2 in our sample support previous findings for low mass-loss rate AGB stars. Our measured 32 S/ 34 S ratios for the two stars R Dor and W Hya agree well with solar values within uncertainties, indicating that these ratios likely reflect the isotopic composition of the stars’ natal clouds and deviate for three stars ( o Ceti, R Leo, and EP Aqr), which could be due to the metallicity and/or excitation conditions within various sources.

• Gorai, Prasanta; Taniguchi, Kotomi; Tan, Jonathan C.; Gómez-Garrido, Miguel; Rosero, Viviana & Jiménez-Serra, Izaskun [Vis alle 14 forfattere av denne artikkelen] (2025). The SOFIA Massive (SOMA) star formation Q-band follow-up: Hydrogen recombination lines towards high-mass protostars. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 702. doi: 10.1051/0004-6361/202556220. Fulltekst i vitenarkiv Vis sammendrag

  Context . Hydrogen recombination lines (HRLs) are valuable diagnostics of the physical conditions in ionized regions surrounding high-mass stars. Understanding these lines, including broadening mechanisms and intensity trends, can provide insights into HII region densities, temperatures, and kinematics. Aims . This study aims to investigate the physical properties of ionized gas around massive protostars by analysing the HRLs (H α and H β ) in the Q band. Methods . We carried out observations using the Yebes 40m radio telescope in the Q band (30.5–50 GHz) towards six high-mass protostars selected from the SOMA Survey (G45.12+0.13, G45.47+0.05, G28.20−0.05, G35.20−0.74, G19.08−0.29, and G31.28+0.06). The observed line profiles were analysed to assess broadening mechanisms, and electron densities and temperatures were derived. The results were compared with available Q-band data from the TianMa 65-m Radio Telescope (TMRT) that have been reported in the literature, and ALMA Band 1 (35–50 GHz) Science Verification observations towards Orion KL, analysed in this study. Results . A total of eight H α (n = 51 to 58) and ten H β (n = 64 to 73) lines were detected towards G45.12+0.13, G45.47+0.05, and G28.20−0.05; there were no detections in other sources. We derived electron densities of ~1−5 × 10 6 cm −3 and temperatures of 8000–10 000 K for the sources. However, for Orion KL, we obtained an electron density one order of magnitude lower, while its temperature was found to be more similar. Interestingly, G45.12 and G28.20 show an increasing intensity trend with frequency for both H α and H β transitions, contrary to the decreasing trend observed in Orion KL. Conclusions . The line widths of the detected HRLs indicate contributions from both thermal and dynamical broadening, suggesting the presence of high-temperature ionized gas that is likely kinematically broadened (e.g. due to turbulence, outflows, rapid rotation, or stellar winds). Pressure broadening caused by electron density may also have a minor effect. We discuss different scenarios to explain the measured line widths of the HRLs. The contrasting intensity trends between the sources may reflect variations in local physical conditions or radiative transfer effects, highlighting the need for further investigation through higher-resolution observations and detailed modelling.

• Saberi, Maryam; Jafarzadeh, S.; Wedemeyer, Sven; Gafeira, R.; Szydlarski, Mikolaj & Jess, D. B. [Vis alle 7 forfattere av denne artikkelen] (2025). The Sun at millimeter wavelengths: V. Magnetohydrodynamic waves in a fibrillar structure. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 693. doi: 10.1051/0004-6361/202451833. Fulltekst i vitenarkiv Vis sammendrag

  Magnetohydrodynamic (MHD) waves, playing a crucial role in transporting energy through the solar atmosphere, manifest in various chromospheric structures. Here, we investigated MHD waves in a long-lasting dark fibril using high-temporal-resolution (2 s cadence) Atacama Large Millimeter/submillimeter Array (ALMA) observations in Band 6 (centered at 1.25 mm). We detected oscillations in brightness temperature, horizontal displacement, and width at multiple locations along the fibril, with median periods and standard deviations of 240 ± 114 s, 225 ± 102 s, and 272 ± 118 s, respectively. Wavelet analysis revealed a combination of standing and propagating waves, suggesting the presence of both MHD kink and sausage modes. Less dominant than standing waves, oppositely propagating waves exhibit phase speeds (median and standard deviation of distributions) of 74 ± 204 km/s, 52 ± 197 km/s, and 28 ± 254 km/s for the three observables, respectively. This work demonstrates ALMA’s capability to effectively sample dynamic fibrillar structures, despite previous doubts. This provides valuable insights into wave dynamics in the upper chromosphere.

• Khouri, T.; Tafoya, D.; Vlemmings, W.H.T.; Olofsson, H.; Contreras, C. Sánchez & Alcolea, J. [Vis alle 16 forfattere av denne artikkelen] (2025). ALMA observations of CO isotopologues towards six obscured post-asymptotic giant branch stars. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 694. doi: 10.1051/0004-6361/202452500. Fulltekst i vitenarkiv Vis sammendrag

  Context. Low- and intermediate-mass stars evolve through the asymptotic giant branch (AGB) when an efficient mass-loss process removes a significant fraction of their initial mass. For most sources, this mass-loss process relies on the interplay between convection, stellar pulsations, and dust formation. However, predicting the mass-loss history of a given star from first principles is complex and not yet feasible at present. At the end of the AGB, at least some stars experience a substantial increase in their mass-loss rate for unknown reasons, leading to the creation of post-AGB objects that are completely enshrouded in thick dusty envelopes. Recent studies have suggested that some of these sources may be the product of interactions between an evolved star with a close companion. Aims. We observed six obscured post-AGB stars (four C-rich and two O-rich sources) to constrain the properties of their circumstellar envelopes, recent mass-loss histories, and initial masses of the central stars. Methods. We used observations of the J = 2 − 1 line of 13CO, C17O, and C18O with the Atacama Large Millimeter/submillimeter Array (ALMA) to determine the circumstellar gas masses and the 17O/18O isotopic ratios, the latter of which can be used to infer initial stellar masses. These results were interpreted in the context of comparisons with stellar evolution models in the literature and existing observations of other post-AGB stars. Results. Based on the inferred 17O/18O isotopic ratios, we find all stars to have relatively low initial masses (< 2 M⊙), contrary to literature indications of higher masses for some sources. One of the C-rich sources, HD 187885, has a low 17O/18O ratio; coupled with a low metallicity, this would imply a relatively low mass (∼1.15 M⊙) for a carbon star. For all but one source (GLMP 950), we observe kinematic components with velocities of ≳30 km s−1, which are higher than typical AGB wind expansion velocities. For most sources, these higher velocity outflows display point-symmetric morphologies. The case of Hen 3-1475 is especially spectacular, with the high-velocity molecular outflow appearing to be interleaved with the high-velocity outflow of ionised gas observed at optical wavelengths. Based on the size of the emission regions of the slow components of the outflows, we derived typical kinematic ages associated with the C18O J = 2 − 1 emission of ≲1500 years and obtained relatively high associated mass-loss rates (≳10−4 M⊙ yr−1). The sources with known spectral types are found to have evolved faster than expected, compared to stellar evolutionary models.

• Aghdam, Sima T.; Javadi, Atefeh; Hashemi, Seyedazim; Abdollahi, Mahdi; Loon, Jacco Th. van & Khosroshahi, Habib [Vis alle 9 forfattere av denne artikkelen] (2024). The Complex Star Formation History of the Halo of NGC 5128 (Cen A). The Astrophysical Journal (ApJ). ISSN 0004-637X. 972(1). doi: 10.3847/1538-4357/ad57c0. Fulltekst i vitenarkiv Vis sammendrag

  NGC 5128 (Cen A) is the nearest giant elliptical galaxy and one of the brightest extragalactic radio sources in the sky, boasting a prominent dust lane and jets emanating from its nuclear supermassive black hole. In this paper, we construct the star formation history (SFH) of two small fields in the halo of NGC 5128: a northeastern field (Field 1) at a projected distance of ∼18.8 kpc from the center, and a southern field (Field 2) ∼9.9 kpc from the center. Our method is based on identifying long-period variable (LPV) stars that trace their sibling stellar population and hence historical star formation due to their high luminosity and strong variability; we identified 395 LPV stars in Field 1 and 671 LPV stars in Field 2. Even though the two fields are ∼28 kpc apart on opposite sides from the center, they show similar SFHs. In Field 1, the star formation rate (SFR) increased significantly around t ∼ 800 Myr and t ∼ 3.8 Gyr and in Field 2, the SFR increased considerably around t ∼ 800 Myr, t ∼ 3.8 Gyr, and t ∼ 6.3 Gyr, where t is the lookback time. The increase in SFR ∼800 Myr ago agrees with previous suggestions that the galaxy experienced a merger around that time. The SFH reconstructed from LPV stars supports a scenario in which multiple episodes of nuclear activity lead to episodic jet-induced star formation. While there is no catalog of LPV stars for the central part of NGC 5128, applying our method to the outer regions (for the first time in a galaxy outside the Local Group) has enabled us to put constraints on the complex evolution of this cornerstone galaxy.

• Khouri, T.; Olofsson, H.; Vlemmings, W.H.T.; Schirmer, T.; Tafoya, D. & Maercker, M. [Vis alle 9 forfattere av denne artikkelen] (2024). An empirical view of the extended atmosphere and inner envelope of the asymptotic giant branch star R Doradus: I. Physical model based on CO lines. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 685. doi: 10.1051/0004-6361/202348382. Fulltekst i vitenarkiv Vis sammendrag

  Context. The mass loss experienced on the asymptotic giant branch (AGB) at the end of the lives of low- and intermediate-mass stars is widely accepted to rely on radiation pressure acting on newly formed dust grains. Dust formation happens in the extended atmospheres of these stars, where the density, velocity, and temperature distributions are strongly affected by convection, stellar pulsation, and heating and cooling processes. The interaction between these processes and how that affects dust formation and growth is complex. Hence, characterising the extended atmospheres empirically is paramount to advance our understanding of the dust formation and wind-driving processes. Aims. We aim to determine the density, temperature, and velocity distributions of the gas in the extended atmosphere of the AGB star R Dor. Methods. We acquired observations using ALMA towards R Dor to study the gas through molecular line absorption and emission. We modelled the observed 12CO v = 0,  J = 2 − 1, v = 1,  J = 2 − 1, and 3 − 2 and 13CO v = 0,  J = 3 − 2 lines using the 3D radiative transfer code LIME to determine the density, temperature, and velocity distributions up to a distance of four times the radius of the star at sub-millimetre wavelengths. Results. The high angular resolution of the sub-millimetre maps allows for even the stellar photosphere to be spatially resolved. By analysing the absorption against the star, we infer that the innermost layer in the near-side hemisphere is mostly falling towards the star, while gas in the layer above that seems to be mostly outflowing. Interestingly, the high angular resolution of the ALMA Band 7 observations reveal that the velocity field of the gas seen against the star is not homogenous across the stellar disc. The gas temperature and density distributions have to be very steep close to the star to fit the observed emission and absorption, but they become shallower for radii larger than ∼1.6 times the stellar sub-millimetre radius. While the gas mass in the innermost region is hundreds of times larger than the mass lost on average by R Dor per pulsation cycle, the gas densities just above this region are consistent with those expected based on the mass-loss rate and expansion velocity of the large-scale outflow. Our fits to the line profiles require the velocity distribution on the far side of the envelope to be mirrored, on average, with respect to that on the near side. Using a sharp absorption feature seen in the CO v = 0,  J = 2 − 1 line, we constrained the standard deviation of the stochastic velocity distribution in the large-scale outflow to be ≲0.4 km s−1. We characterised two blobs detected in the CO v = 0,  J = 2 − 1 line and found densities substantially larger than those of the surrounding gas. The two blobs also display expansion velocities that are high relative to that of the large-scale outflow. Monitoring the evolution of these blobs will lead to a better understanding of the role of these structures in the mass-loss process of R Dor.

• Wedemeyer, Sven; Barta, Miroslav; Brajša, Roman; Chai, Yi; Costa, Joaquim & Gary, Dale [Vis alle 38 forfattere av denne artikkelen] (2024). Science development study for the Atacama Large Aperture Submillimeter Telescope (AtLAST): Solar and stellar observations. Open Research Europe. 4. doi: 10.12688/openreseurope.17453.1. Fulltekst i vitenarkiv Vis sammendrag

  Observations at (sub-)millimeter wavelengths offer a complementary perspective on our Sun and other stars, offering significant insights into both the thermal and magnetic composition of their chromospheres. Despite the fundamental progress in (sub-)millimeter observations of the Sun, some important aspects require diagnostic capabilities that are not offered by existing observatories. In particular, simultaneously observations of the radiation continuum across an extended frequency range would facilitate the mapping of different layers and thus ultimately the 3D structure of the solar atmosphere. Mapping large regions on the Sun or even the whole solar disk at a very high temporal cadence would be crucial for systematically detecting and following the temporal evolution of flares, while synoptic observations, i.e., daily maps, over periods of years would provide an unprecedented view of the solar activity cycle in this wavelength regime. As our Sun is a fundamental reference for studying the atmospheres of active main sequence stars, observing the Sun and other stars with the same instrument would unlock the enormous diagnostic potential for understanding stellar activity and its impact on exoplanets. The Atacama Large Aperture Submillimeter Telescope (AtLAST), a single-dish telescope with 50m aperture proposed to be built in the Atacama desert in Chile, would be able to provide these observational capabilities. Equipped with a large number of detector elements for probing the radiation continuum across a wide frequency range, AtLAST would address a wide range of scientific topics including the thermal structure and heating of the solar chromosphere, flares and prominences, and the solar activity cycle. In this white paper, the key science cases and their technical requirements for AtLAST are discussed.

• Parto, Tahere; Dehghani, Shahrzad; Javadi, Atefeh; Saremi, Elham; Loon, Jacco Th. van & Khosroshahi, Habib G. [Vis alle 10 forfattere av denne artikkelen] (2023). The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. V. The Star Formation History of Sagittarius Dwarf Irregular Galaxy Derived from Long-period Variable Stars. The Astrophysical Journal (ApJ). ISSN 0004-637X. 942(1). doi: 10.3847/1538-4357/aca471. Fulltekst i vitenarkiv Vis sammendrag

  We conducted an optical monitoring survey of the Sagittarius dwarf irregular galaxy (SagDIG) during the period of 2016 June–2017 October, using the 2.5 m Isaac Newton Telescopeat La Palama. Our goal was to identify long-period variable stars (LPVs), namely, asymptotic giant branch stars (AGBs) and red supergiant stars, to obtain the star formation history of isolated, metal-poor SagDIG. For our purpose, we used a method that relies on evaluating the relation between luminosity and the birth mass of these most evolved stars. We found 27 LPV candidates within 2 half-light radii of SagDIG. 10 LPV candidates were in common with previous studies, including one extreme-AGB (x-AGB). By adopting the metallicity Z = 0.0002 for older populations and Z = 0.0004 for younger ages, we estimated that the star formation rate changes from 0.0005 ± 0.0002 M⊙ yr−1 kpc−2 (13 Gyr ago) to 0.0021 ± 0.0010 M⊙ yr−1 kpc−2 (0.06 Gyr ago). Like many dwarf irregular galaxies, SagDIG has had continuous star formation activity across its lifetime, though with different rates, and experiences an enhancement of star formation since z ≃ 1. We also evaluated the total stellar mass within 2 half-light radii of SagDIG for three choices of metallicities. For metallicity Z = 0.0002 and 0.0004, we estimated the stellar mass M* = (5.4 ± 2.3) × 106 and (3.0 ± 1.3) × 106 M⊙, respectively. Additionally, we determined a distance modulus of μ = 25.27 ± 0.05 mag, using the tip of the red giant branch.

• Abdollahi, Hedieh; Javadi, Atefeh; Mirtorabi, Mohammad Taghi; Saremi, Elham; Loon, Jacco Th. van & Khosroshahi, Habib G. [Vis alle 12 forfattere av denne artikkelen] (2023). The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. VI. The Star Formation History and Dust Production in Andromeda IX. The Astrophysical Journal (ApJ). ISSN 0004-637X. 948(1). doi: 10.3847/1538-4357/acbbc9. Fulltekst i vitenarkiv Vis sammendrag

  We present a photometric study of the resolved stellar populations in Andromeda IX (And IX), the closest satellite to M31, a metal-poor and low-mass dwarf spheroidal galaxy. We estimate a distance modulus of ${24.56}_{-0.15}^{+0.05}$ mag based on the tip of the red giant branch. By probing the variability of asymptotic giant branch stars, we study the star formation history of And IX. We identified 50 long-period variables (LPVs) in And IX using the Isaac Newton Telescope in two filters, the Sloan $i^{\prime} $ and Harris V. In this study, we selected LPVs within two half-light radii with amplitudes in the range of 0.2–2.20 mag. It is found that the peak of star formation reaches ∼8.2 ± 3.1 × 10−4M⊙ yr−1 at ≈6 Gyr ago. Our findings suggest an outside-in galaxy formation scenario for And IX with a quenching occurring ${3.65}_{-0.13}^{+1.52}$ Gyr ago with a star formation rate (SFR) in the order of 2.0 × 10−4M⊙ yr−1 at redshift <0.5. We calculate the total stellar mass by integrating the SFR within two half-light radii ∼3.0 × 105M⊙. By employing spectral energy distribution fitting for the observed LPVs in And IX, we evaluate a mass-loss rate in the range of 10−7 ≤ $\dot{M}$ ≤ 10−5M⊙ yr−1. Finally, we show that the total mass deposition to the interstellar medium (ISM) is ∼2.4 × 10−4M⊙ yr−1 from the C- and O-rich types of dust-enshrouded LPVs. The ratio of the total mass returned to the ISM by LPVs to the total stellar mass is ∼8.0 × 10−10 yr−1, and so at this rate it would take ∼1 Gyr to reproduce this galaxy.

• Mohan, Atul; Wedemeyer, Sven; Pandit, Sneha; Saberi, Maryam & Hauschildt, Peter H. (2021). EMISSA (Exploring Millimeter Indicators of Solar-Stellar Activity): I. The initial millimeter–centimeter main-sequence star sample. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 655. doi: 10.1051/0004-6361/202142095. Fulltekst i vitenarkiv Vis sammendrag

  Context. Due to their wide wavelength coverage across the millimeter to centimeter (mm–cm) range and their increased sensitivity, modern interferometric arrays facilitate observations of the thermal and non-thermal radiation that is emitted from different layers in the outer atmospheres of stars. Aims. We study the spectral energy distribution ( S obs ( ν )) of main-sequence stars based on archival observations in the mm–cm range with the aim to study their atmospheric stratification as a function of stellar type. Methods. The main-sequence stars with significant detection in mm bands were identified in the ALMA Science Archive. These data were then complemented with spectral flux data in the extreme ultraviolet to cm range as compiled from various catalogues and observatory archives. We compared the resultant S obs ( ν ) of each star with a photospheric emission model ( S mod ( ν )) calculated with the PHOENIX code. The departures of S obs ( ν ) from S mod ( ν ) were quantified in terms of a spectral flux excess parameter (Δ S ∕ S mod ) and studied as a function of stellar type. Results. The initial sample consists of 12 main-sequence stars across a broad range of spectral types from A1 to M3.5 and the Sun-as-a-star as reference. The stars with T eff = 3000–7000 K (F–M type) showed a systematically higher S obs ( ν ) than S mod ( ν ) in the mm–cm range. Their Δ S ∕ S mod exhibits a monotonic rise with decreasing frequency. The steepness of this rise is higher for cooler stars in the T eff = 3000–7000 K range, although the single fully convective star ( T eff ~ 3000 K) in the sample deviates from this trend. Meanwhile, S obs ( ν ) of the A-type stars agrees with S mod ( ν ) within errors. Conclusions. The systematically high Δ S ∕ S mod in F–M stars indicates hotter upper atmospheric layers, that is, a chromosphere and corona in these stars, like for the Sun. The mm–cm Δ S ∕ S mod spectrum offers a way to estimate the efficiency of the heating mechanisms across various outer atmospheric layers in main-sequence stars, and thereby to understand their structure and activity. We emphasise the need for dedicated surveys of main-sequence stars in the mm–cm range.

• Groenewegen, Martin & Saberi, Maryam (2021). Reflections on the photodissociation of CO in circumstellar envelopes. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 649. doi: 10.1051/0004-6361/202039994. Fulltekst i vitenarkiv Vis sammendrag

  Carbon monoxide (CO) is the most abundant molecule after molecular hydrogen and is important for the chemistry in circumstellar envelopes around evolved stars. When modelling the strength and shape of molecular lines, the size of the CO envelope is an input parameter and influences the derived mass-loss rates. In particular the low-J transition CO lines are sensitive to the CO photodissociation radius. Recently, new CO photodissociation radii have been published using different formalisms that differ considerably. One set of calculations is based on an escape-probability formalism that uses numerical approximations derived in the early 1980s. The accuracy of these approximations is investigated and it is shown that they are less accurate than claimed. Improved formalism are derived. Nevertheless, the changes in the CO envelope size are small to moderate and less than 2% for models with 10 −7 &lt; Ṁ &lt; 10 −4 M ⊙ yr −1 and at most 7% for model with Ṁ = 10 −8 M ⊙ yr −1 .

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• Wedemeyer, Sven; Kirkaune, Mats; Gunar, Stanislav; Hudson, Hugh; Mohan, Atul & Simões, Paulo [Vis alle 22 forfattere av denne artikkelen] (2025). Radio and Millimeter Observations of the Sun - Probing the Solar Origins of Space Weather. Fulltekst i vitenarkiv Vis sammendrag

  Observations at radio and millimeter wavelengths provide a unique window into the thermal and magnetic structure of the solar chromosphere and corona, where the solar drivers of space weather are rooted. The Atacama Large Millimeter/submillimeter Array (ALMA) has marked a major advance in solar observations by providing unprecedented spatial and temporal resolution. These capabilities enable detailed studies of dynamic small-scale processes that are fundamental to the mechanisms driving solar flares, coronal mass ejections, and the acceleration of solar energetic particles. Looking ahead, the proposed Atacama Large Aperture Submillimeter Telescope (AtLAST), a 50-meter single-dish facility, would deliver rapid multi-wavelength full-disk scans with cadences of one minute or less - an essential capability for capturing fast-evolving solar phenomena. The Square Kilometer Array (SKA), currently under construction, will observe at lower frequencies, thus probing the Sun’s corona. Beyond advancing fundamental physical understanding, solar observations at millimeter wavelengths hold strong potential for space weather forecasting. They provide sensitive diagnostics of chromospheric and coronal heating and dynamics, offering real-time constraints for models used in operational prediction systems. The Solaris project - designed to enable continuous, year-round observations from sites in Antarctica and the Arctic - will serve as an important demonstrator of this capability. This poster will present recent advances in solar radio/mm observations, highlight synergies with forward modeling and data-driven simulations, and outline opportunities with upcoming facilities such as AtLAST, Solaris, and SKA. Together, these developments demonstrate the growing role of millimeter observations both in unraveling the solar origins of space weather and in providing critical observational input for future forecasting frameworks.

• Saberi, Maryam (2025). Multi-wavelength insights into the recycled material from AGB Stars. Fulltekst i vitenarkiv
• Saberi, Maryam & Khouri, Theo (2024). ALMA observations of Ti- and Al-bearing species in Mira. Fulltekst i vitenarkiv
• Saberi, Maryam (2024). The impact of evolved stars on the Galactic chemical enrichment. Fulltekst i vitenarkiv
• Saberi, Maryam (2024). Tracing the impact of Evolved Stars on the Galactic Chemical enrichment. Fulltekst i vitenarkiv
• Kirkaune, Mats; Brunvoll, Aline Rangøy & Saberi, Maryam (2024). Avsløring av solas hemmeligheter. Fulltekst i vitenarkiv
• Saberi, Maryam (2023). ALMA observations of dust forming region in the outflow of Mira. Fulltekst i vitenarkiv
• Saberi, Maryam (2023). The contribution of AGB stars on the Galactic Fluorine budget. Fulltekst i vitenarkiv
• Saberi, Maryam; Khouri, Theo; Velilla-Prieto, L.; Fonfria, . P.; Vlemmings, W. & Wedemeyer, Sven (2021). Tracing the role of AGB stars in the Galactic Fluorine budget. Fulltekst i vitenarkiv
• Wedemeyer, Sven; Szydlarski, Mikolaj; Jafarzadeh, Shahin; Henriques, Vasco Manuel de Jorge; Eklund, Henrik & Gomez, Juan Camilo Guevara [Vis alle 10 forfattere av denne artikkelen] (2021). Observing the Sun with ALMA - First results and future opportunities. Fulltekst i vitenarkiv
• Wedemeyer, Sven; Szydlarski, Mikolaj; Jafarzadeh, Shahin; Henriques, Vasco Manuel de Jorge; Eklund, Henrik & Gomez, Juan Camilo Guevara [Vis alle 10 forfattere av denne artikkelen] (2021). Five years observing the solar chromosphere with ALMA - First results and future opportunities. Fulltekst i vitenarkiv
• Wedemeyer, Sven; Szydlarski, Mikolaj; Jafarzadeh, Shahin; Henriques, Vasco; Eklund, Henrik & Gomez, Juan Camilo Guevara [Vis alle 10 forfattere av denne artikkelen] (2021). Five years observing the solar chromosphere with ALMA - First results and future opportunities. Fulltekst i vitenarkiv
• Saberi, Maryam (2020). UV chemistry in the circumstellar envelopes around evolved stars. Fulltekst i vitenarkiv

Se alle arbeider i NVA