arXiv subjects

Mikako Matsuura

Publications and source records attributed to Mikako Matsuura.

At least 19 recordsLinked to original sources

arXiv2026

Milky Way's warped disc traced by AGB stars

While the presence of the Galactic warp has long been established from observations of \HI\, gas, the \textit{Gaia} measurements of over 1 billion stars with parallaxes have enabled much more detailed studies using stellar populations. Here, we demonstrate that asymptotic giant branch (AGB) stars, an evolved phase of low- and intermediate-mass stars, can serve as an effective tracer of the Galactic warp. We use two distinct AGB populations: C-rich AGB stars, representing stars of about 1~Gyr in age with main-sequence masses of 2--2.5~\Msun, and intermediate-mass (3--5~\Msun) O-rich AGB stars, corresponding to ages of 100--300~Myr. The downward warp traced by O-rich AGB stars is consistent with that found from Cepheids, which is expected given their similar ages. The more numerous C-rich AGB stars clearly reveal the Galactic warp over a wide range of azimuthal angles. Their warp appears to reach larger amplitudes than that of Cepheids across azimuthal angles. Our results show that C-rich AGB stars, together with intermediate-mass O-rich AGB stars, provide new constraints on the Galactic warp at intermediate stellar ages, offering a new insight into the stellar age and warp amplitude relation.

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arXiv2026

The outer rings of SN 1987A from year 1994 to 2024: morphology, light curves, and optical to mid-infrared spectra

The outer rings (ORs) of Supernova (SN) 1987A were ejected ~20000 years before the explosion. Their characterisation is crucial for constraining the properties of the progenitor of this famous SN. While numerous studies investigated in detail the ejecta, equatorial ring (ER), and reverse shocks, few were dedicated to the ORs. We fill this gap and investigate the ORs physical properties. We analyse data obtained over a long temporal period, from multiple instruments, and over a wide wavelength range from optical to mid-infrared of the northern and southern ORs (NOR and SOR). We combine observations taken with HST between 1994 and 2022, VLT/MUSE in 2023, and JWST in 2022 and 2024. We measure emission flux in the ORs in HST and JWST/NIRCam images. We extract optical and mid-infrared spectra for the ORs in MUSE and JWST/MIRI/MRS data and measure line emission fluxes. We analyse the evolution of the ORs clumps' morphology over time with HST. The optical lightcurves of the ORs have shown a steady decline with time over the last 30 years. It is expected as the ORs were ionised by the initial SN UV-flash and are since then fading. The observations do not show any sign of interaction of the SN ejecta with the ORs. We estimated the decay times for [O III] to be 900 and 680 days for the NOR and SOR, and for Halpha+[N II] to be 15870 and 7160 days for the NOR and SOR. We constrained the temperature from the optical [N II] lines to 13400-16900K and 11800-14500K for the NOR and SOR. We constrained the electron density from the optical [S II] lines to 610-670cm-3 and 720-790cm-3 for the NOR and SOR. The spectra of the ORs differ significantly from the spectrum of the ER in lines detected and line ratios. The ORs will likely keep on fading for the next years, until the SN ejecta sweep them up. Continued monitoring of SN1987A and its ring system at all wavelengths is essential to capture this instant.

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arXiv2026

Summary of Discussion Sessions from "The Dusty Universe 2025: The Fifth Pandust Conference"

"The Dusty Universe: The Fifth Pandust Conference" took place in Tucson (AZ, USA) from November 10 until 14, 2025. The goal of this meeting was to get the dust community together to review where we are, hear exciting new results, and make plans for the future. The meeting encompassed all aspects of dust investigations including observations, theory, modeling, and laboratory studies. The conference consisted of invited review talks, contributed talks and posters. Science topics included interstellar dust (Milky Way & nearby galaxies), circumstellar dust (including Solar System & exoplanets), dust in Galaxies (including high-z), lifecycle of dust, and future needs (laboratory, theory, & observations), with a particular focus on results from JWST and ALMA, and on nanodust (including PAHs). On November 12th, we organized breakout discussion sessions covering a wide range of interesting dust-related topics. The purpose of this document is to capture the main topics/questions that were discussed, the key conclusions of these discussions, the challenges and possible solutions that were brought up, and the open questions that still remain to be answered. We hope that this document records our findings and challenges for the future generation.

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arXiv2026

Detection of CO$_2$ ice in the planetary nebula NGC 6302

Using JWST/MIRI observations, we report the detection of CO$_2$ ice in the dusty torus of the planetary nebula NGC 6302, an environment generally considered hostile to fragile molecular species and ices due to intense UV irradiation. This detection accompanies cold (20-50 K) gas-phase CO$_2$ along the same sightlines. The ice absorption profile exhibits a double-peak profile, a characteristic of pure, crystalline CO$_2$ ice. The CO$_2$ gas-to-ice ratio is more than an order of magnitude higher than in young stellar objects, pointing to distinct ice formation or processing mechanisms in evolved stellar environments. This discovery demonstrates that the dusty torus provides sufficient shielding to harbour ice chemistry, and that ice-mediated surface reactions must be incorporated into chemical models of planetary nebulae.

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arXiv2026

3D insights into SN 1987A: ALMA observations compared to hydrodynamical explosion simulations

We obtain three-dimensional distributions of CO and SiO molecules from high spatial resolution (0.03--0.06") ALMA observations of SN 1987A at two different epochs. The evolution between these two epochs is consistent with homologous expansion. From these 3D maps, we reconstruct the 3D mass distributions of the ejecta in CO and SiO molecules, which we compare with those obtained by state-of-the-art, long-time hydrodynamical supernova explosion models computed with the Prometheus-HotB code for 10 different progenitors, including both red and blue supergiants. The models which best match the mass distributions correspond to explosions of binary-merger blue supergiant progenitors; at least two such models approximately reproduce the observed CO morphology. In contrast, the SiO velocity distribution and morphology are not as well reproduced in these models, indicating insufficient mixing of Si into the outer layers already at the progenitor stage. The theoretical models suggest a strong correlation between the centre of mass of the densest carbon- and oxygen-rich ejecta and the direction of the neutron-star kick. If such a correlation also applies to the CO emission in the ejecta of SN 1987A, the kick of the compact remnant is expected to point towards the observer, at an angle of approximately $45^\circ$ to the north.

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arXiv2025

Detection of CH3+ in the O-rich planetary nebula NGC 6302

Planetary nebulae are sites where ejected stellar material evolves into complex molecules, but the precise physical conditions and chemical routes that govern these processes are unclear. The presence of abundant carbon-rich molecules in O-rich environments poses particular challenges. Here we report the first detection of methyl cation (CH3+) in any planetary nebula, observed in the O-rich nebula NGC 6302 using JWST MIRI/MRS observations. CH3+ is a key driver of organic chemistry in UV-irradiated environments. Spatially resolved observations reveal that CH3+ is co-located with 12CO, H2, H II, HCO+, and Polycyclic aromatic hydrocarbons (PAHs). LTE modelling of the CH3+ emission yields excitation temperatures of 500-800K in the inner bubble and torus, rising to 1000-2000K in the outer bubble of NGC 6302, with column densities ranging from ~10^11 to 10^13 cm^-2. This detection demonstrates that hydrocarbon radical chemistry must be incorporated into planetary nebulae chemical models. Further near-IR observations are crucial to map different chemical networks operating in these environments.

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arXiv2025

JWST/NIRCam imaging of the Bipolar Planetary Nebula NGC 6537: the (Infra)red Spider, Revealed

We present James Webb Space Telescope (JWST) near-infrared (NIRCam) Br$α$, H$_2$, [Fe II], and PAH imaging of the molecule-rich, high-excitation bipolar planetary nebula (PN) NGC 6537 (the Red Spider), complemented by new ALMA and Chandra observations and archival HST images. The resulting multiwavelength view of the Red Spider establishes the detailed lobe/torus structure of the nebula and the mass-loss history of its progenitor star. The extinction-penetrating JWST/NIRCam Br$α$ and PAH and ALMA 3 mm continuum imaging exposes the complexity of the ionized inner nebula. JWST/NIRCam H$_2$ imaging traces the full, $\sim$1.1 pc extent of the bubble-like lobes formed by fast ($\sim$300-400 km s$^{-1}$) polar outflows, while ALMA $^{13}$CO(1-0) mapping reveals a point-symmetric, slowly ($\sim$10 km s$^{-1}$) expanding equatorial torus of radius $\sim$0.13 pc. In striking contrast, the [Fe II] image displays an extended S-shaped emission morphology that traces collisions between an active, collimated wind and slower-moving material along the lobe rims. No X-rays are detected from the nebula or its central star in deep Chandra/HRC-I imaging. However, the combined HST and JWST imaging reveals a near-IR excess at the central star indicative of emission from hot ($\sim$1000 K) circumstellar dust. We propose that interactions between the nebular progenitor star and a close companion are responsible for the ejection of NGC 6537's molecular torus, the formation of a circumbinary dust disk, and the launching of fast, wandering, collimated outflows that have inflated the polar lobe bubbles traced by near-IR H$_2$ emission and are presently generating the [Fe II]-emitting shocks.

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arXiv2025

The PRIMA promise of deciphering interstellar dust evolution with observations of the nearby Universe

This paper develops a few science cases, using the PRIMA far-IR probe, aimed at achieving several breakthroughs in our understanding of the dust properties and their evolution. We argue that the specific observational capabilities of PRIMA, namely its unprecedented sensitivity over the whole far-IR range and the possibility to obtain continuous spectra between wavelengths 24 and 235 microns, are essential to progress in our understanding of the physics of the interstellar medium and galaxy evolution. Our science cases revolve around observations of nearby galaxies. We discuss the importance of detecting the IR emission of the diffuse interstellar medium of these galaxies, including very low-metallicity systems. We also discuss the opportunity of detecting various solid-state features to understand the mineralogy of interstellar grains. Finally, we stress the unique opportunity brought by the possible simultaneous measures of both the dust continuum and the far-IR fine-structure gas lines. These science cases could be distributed in a few large programs.

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arXiv2025

The JWST/MIRI view of the planetary nebula NGC 6302 I.: a UV irradiated torus and a hot bubble triggering PAH formation

NGC 6302 is a spectacular bipolar planetary nebula (PN) whose spectrum exhibits fast outflows and highly ionized emission lines, indicating the presence of a very hot central star (~220,000 K). Its infrared spectrum reveals a mixed oxygen and carbon dust chemistry, displaying both silicate and polycyclic aromatic hydrocarbon (PAH) features. Using the JWST Mid-Infrared Instrument (MIRI) and Medium Resolution Spectrometer, a mosaic map was obtained over the core of NGC 6302, covering the wavelength range of 5--28 micron and spanning an area of ~18.5 arcsec x15 arcsec. The spatially resolved spectrum reveals ~200 molecular and ionized lines from species requiring ionisation potentials of up to 205 eV. The spatial distributions highlight a complex structure at the nebula's centre. Highly ionized species such as Mg VII and Si VII show compact structures, while lower-ionization species such as H^+ extend much farther outwards, forming filament-defined rims that delineate a bubble. Within the bubble, the H^+ and H_2 emission coincide, while the PAH emission appears farther out, indicating an ionization structure distinct from typical photodissociation regions, such as the Orion Bar. This may be the first identification of a PAH formation site in a PN. This PN appears to be shaped not by a steady, continuous outflow, but by a series of dynamic, impulsive bubble ejections, creating local conditions conducive to PAH formation. A dusty torus surrounds the core, primarily composed of large (micron-sized) silicate grains with crystalline components. The long-lived torus contains a substantial mass of material, which could support an equilibrium chemistry and a slow dust-formation process.

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arXiv2025

JWST observations of the Ring Nebula (NGC 6720) -- II. PAH emission

Polycyclic aromatic hydrocarbons (PAHs) and carbonaceous dust have been observed in clumpy circumstellar environments, yet their formation and evolutionary pathways in such environments remain elusive. We aim to characterize the PAH emission in a clumpy planetary nebula to decipher their formation and evolution pathways. We obtained JWST Near-Infrared Spectrograph (NIRSpec) and Mid-Infrared Instrument (MIRI) integral field unit spectroscopic observations of two individual knots in the Ring Nebula (NGC 6720), a clumpy planetary nebula, and determine the PAH spectral characteristics. We detect the 3.3 and 11.2 um PAH emission bands in both knots but do not detect PAH emission in the 6-9 um range. We supplement our data with Spitzer Infrared Spectrograph (IRS) Short-Low 1 (SL1) and SL2 data, containing 11.2, weak 6.2, and weak 7.7 um PAH emission bands. The JWST data confirm the unusual profile of the 11.2 um band, which is very broad and redshifted with respect to typical 11.2 um PAH profiles. We estimate the PAH population to be largely neutral. The relative integrated surface brightness of the 3.3 and 11.2 um bands indicates the presence of small-sized PAHs, consisting of 35 +/- 6 carbon atoms. We find that the PAH emission is concentrated outside of the clumps, in the inter-clump medium, and confirm the existence of enhanced PAH emission in a narrow 'PAH ring' centred on the central star. This morphology suggests that PAHs formed during the Ring Nebula's asymptotic giant branch phase, in the central star's dust-driven wind.

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arXiv2025

JWST observations of the Ring Nebula (NGC 6720): III. A dusty disk around its Central Star

The planetary nebula NGC 6720, also known as the ``Ring Nebula", is one of the most iconic examples of nearby planetary nebulae whose morphologies present a challenge to our theoretical understanding of the processes that govern the deaths of most stars in the Universe that evolve on a Hubble time. We present new imaging with JWST of the central star of this planetary nebula (CSPN) and its close vicinity, in the near- to mid-IR wavelength range. We find the presence of a dust cloud around the CSPN, both from the spectral energy distribution at wavelengths >~5 micron, as well as radially-extended emission in the 7.7, 10 and 11.3 micron images. From modeling of these data, we infer that the CSPN has a luminosity of 310 Lsun and is surrounded by a dust cloud with a size of ~2600 au, consisting of relatively small amorphous silicate dust grains (radius ~0.01 micron) with a total mass of 1.9 x 10^(-6) M_earth. However, our best-fit model shows a significant lack of extended emission at 7.7 micron -- we show that such emission can arise from a smaller (7.3 x 10^(-7) M_earth) but uncertain mass of (stochastically-heated) ionized PAHs. However, the same energetic radiation also rapidly destroys PAH molecules, suggesting that these are most likely being continuously replenished, via the outgassing of cometary bodies and/or the collisional grinding of planetesimals. We also find significant photometric variability of the central source that could be due to the presence of a close dwarf companion of mass < ~0.1 Msun.

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arXiv2024

The Green Monster hiding in front of Cas A: JWST reveals a dense and dusty circumstellar structure pockmarked by ejecta interactions

JWST observations of the young Galactic supernova remnant Cassiopeia A revealed an unexpected structure seen as a green emission feature in colored composite MIRI F1130W and F1280W images - hence dubbed the Green Monster - that stretches across the central parts of the remnant in projection. Combining the kinematic information from NIRSpec and MIRI MRS with the multi-wavelength imaging from NIRCam and MIRI, we associate the Green Monster with circumstellar material that was lost during an asymmetric mass-loss phase. MIRI images are dominated by dust emission but its spectra show emission lines from Ne, H and Fe with low radial velocities indicative of a CSM nature. An X-ray analysis of this feature in a companion paper (Vink et al. 2024) supports its CSM nature and detects significant blue shifting, thereby placing the Green Monster on the near side, in front of the Cas A SN remnant. The most striking features of the Green Monster are dozens of almost perfectly circular 1" - 3" sized holes, most likely created by interaction between high-velocity SN ejecta material and the CSM. Further investigation is needed to understand whether these holes were formed by small 8000-10500 km/s N-rich ejecta knots that penetrated and advanced out ahead of the remnant's 5000 - 6000 km/s outer blastwave, or by narrow ejecta fingers that protrude into the forward-shocked CSM. The detection of the Green Monster provides further evidence of the highly asymmetric mass-loss that Cas A's progenitor star underwent prior to explosion.

astro-ph.HE↗

arXiv2024

A JWST Survey of the Supernova Remnant Cassiopeia A

We present initial results from a JWST survey of the youngest Galactic core-collapse supernova remnant Cassiopeia A (Cas A), made up of NIRCam and MIRI imaging mosaics that map emission from the main shell, interior, and surrounding circumstellar/interstellar material (CSM/ISM). We also present four exploratory positions of MIRI/MRS IFU spectroscopy that sample ejecta, CSM, and associated dust from representative shocked and unshocked regions. Surprising discoveries include: 1) a web-like network of unshocked ejecta filaments resolved to 0.01 pc scales exhibiting an overall morphology consistent with turbulent mixing of cool, low-entropy matter from the progenitor's oxygen layer with hot, high-entropy matter heated by neutrino interactions and radioactivity, 2) a thick sheet of dust-dominated emission from shocked CSM seen in projection toward the remnant's interior pockmarked with small (approximately one arcsecond) round holes formed by knots of high-velocity ejecta that have pierced through the CSM and driven expanding tangential shocks, 3) dozens of light echoes with angular sizes between 0.1 arcsecond to 1 arcminute reflecting previously unseen fine-scale structure in the ISM. NIRCam observations place new upper limits on infrared emission from the neutron star in Cas A's center and tightly constrain scenarios involving a possible fallback disk. These JWST survey data and initial findings help address unresolved questions about massive star explosions that have broad implications for the formation and evolution of stellar populations, the metal and dust enrichment of galaxies, and the origin of compact remnant objects.

astro-ph.HE↗

arXiv2024

Deep JWST/NIRCam imaging of Supernova 1987A

JWST/NIRCam obtained high angular-resolution (0.05-0.1''), deep near-infrared 1--5 micron imaging of Supernova (SN) 1987A taken 35 years after the explosion. In the NIRCam images, we identify: 1) faint H2 crescents, which are emissions located between the ejecta and the equatorial ring, 2) a bar, which is a substructure of the ejecta, and 3) the bright 3-5 micron continuum emission exterior to the equatorial ring. The emission of the remnant in the NIRCam 1-2.3 micron images is mostly due to line emission, which is mostly emitted in the ejecta and in the hot spots within the equatorial ring. In contrast, the NIRCam 3-5 micron images are dominated by continuum emission. In the ejecta, the continuum is due to dust, obscuring the centre of the ejecta. In contrast, in the ring and exterior to the ring, synchrotron emission contributes a substantial fraction to the continuum. Dust emission contributes to the continuum at outer spots and diffuse emission exterior to the ring, but little within the ring. This shows that dust cooling and destruction time scales are shorter than the synchrotron cooling time scale, and the time scale of hydrogen recombination in the ring is even longer than the synchrotron cooling time scale. With the advent of high sensitivity and high angular resolution images provided by JWST/NIRCam, our observations of SN 1987A demonstrate that NIRCam opens up a window to study particle-acceleration and shock physics in unprecedented details, probed by near-infrared synchrotron emission, building a precise picture of how a SN evolves.

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arXiv2024

Hubble Space Telescope images of SN 1987A: Evolution of the ejecta and the equatorial ring from 2009 to 2022

Supernova (SN) 1987A offers a unique opportunity to study how a spatially resolved SN evolves into a young supernova remnant (SNR). We present and analyze Hubble Space Telescope (HST) imaging observations of SN 1987A obtained in 2022 and compare them with HST observations from 2009 to 2021. These observations allow us to follow the evolution of the equatorial ring (ER), the rapidly expanding ejecta, and emission from the center over a wide range in wavelength from 2000 to 11 000 AA. The ER has continued to fade since it reached its maximum ~8200 days after the explosion. In contrast, the ejecta brightened until day ~11000 before their emission levelled off; the west side brightened more than the east side, which we attribute to the stronger X-ray emission by the ER on that side. The asymmetric ejecta expand homologously in all filters, which are dominated by various emission lines from hydrogen, calcium, and iron. From this overall similarity, we infer the ejecta are chemically well-mixed on large scales. The exception is the diffuse morphology observed in the UV filters dominated by emission from the Mg II resonance lines that get scattered before escaping. The 2022 observations do not show any sign of the compact object that was inferred from highly-ionized emission near the remnant's center observed with JWST. We determine an upper limit on the flux from a compact central source in the [O III] HST image. The non-detection of this line indicates that the S and Ar lines observed with JWST originate from the O free inner Si - S - Ar rich zone and/or that the observed [O III] flux is strongly affected by dust scattering.

astro-ph.HE↗

arXiv2023

JWST NIRCam Observations of SN 1987A: Spitzer Comparison and Spectral Decomposition

JWST NIRCam observations at 1.5-4.5 $μ$m have provided broad and narrow band imaging of the evolving remnant of SN 1987A with unparalleled sensitivity and spatial resolution. Comparing with previous marginally spatially resolved Spitzer IRAC observations from 2004-2019 confirms that the emission arises from the circumstellar equatorial ring (ER), and the current brightness at 3.6 and 4.5 $μ$m was accurately predicted by extrapolation of the declining brightness tracked by IRAC. Despite the regular light curve, the NIRCam observations clearly reveal that much of this emission is from a newly developing outer portion of the ER. Spots in the outer ER tend to lie at position angles in between the well-known ER hotspots. We show that the bulk of the emission in the field can be represented by 5 standard spectral energy distributions (SEDs), each with a distinct origin and spatial distribution. This spectral decomposition provides a powerful technique for distinguishing overlapping emission from the circumstellar medium (CSM) and the supernova (SN) ejecta, excited by the forward and reverse shocks respectively.

astro-ph.SR↗

arXiv2023

JWST observations of the Ring Nebula (NGC 6720): I. Imaging of the rings, globules, and arcs

We present JWST images of the well-known planetary nebula NGC 6720 (the Ring Nebula), covering wavelengths from 1.6$μ$m to 25 $μ$m. The bright shell is strongly fragmented with some 20 000 dense globules, bright in H$_2$, with a characteristic diameter of 0.2 arcsec and density $n_{\rm H} \sim 10^5$-$10^6$ cm$^{-3}$. The shell contains a thin ring of polycyclic aromatic hydrocarbon (PAH) emission. H$_2$ is found throughout the shell and in the halo. H$_2$ in the halo may be located on the swept-up walls of a biconal polar flow. The central cavity is shown to be filled with high ionization gas and shows two linear structures. The central star is located 2 arcsec from the emission centroid of the cavity and shell. Linear features (`spikes') extend outward from the ring, pointing away from the central star. Hydrodynamical simulations are shown which reproduce the clumping and possibly the spikes. Around ten low-contrast, regularly spaced concentric arc-like features are present; they suggest orbital modulation by a low-mass companion with a period of about 280 yr. A previously known much wider companion is located at a projected separation of about 15 000 au; we show that it is an M2-M4 dwarf. The system is therefore a triple star. These features, including the multiplicity, are similar to those seen in the Southern Ring Nebula (NGC 3132) and may be a common aspect of such nebulae.

astro-ph.SR↗

arXiv2023

The messy death of a multiple star system and the resulting planetary nebula as observed by JWST

Planetary nebulae (PNe), the ejected envelopes of red giant stars, provide us with a history of the last, mass-losing phases of 90 percent of stars initially more massive than the Sun. Here, we analyse James Webb Space Telescope (JWST) Early Release Observation (ERO) images of the PN NGC3132. A structured, extended H2 halo surrounding an ionised central bubble is imprinted with spiral structures, likely shaped by a low-mass companion orbiting the central star at 40-60 AU. The images also reveal a mid-IR excess at the central star interpreted as a dusty disk, indicative of an interaction with another, closer companion. Including the previously known, A-type visual companion, the progenitor of the NGC3132 PN must have been at least a stellar quartet. The JWST images allow us to generate a model of the illumination, ionisation and hydrodynamics of the molecular halo, demonstrating the power of JWST to investigate complex stellar outflows. Further, new measurements of the A-type visual companion allow us to derive the value for the mass of the progenitor of a central star to date with excellent precision: 2.86+/-0.06 Mo. These results serve as path finders for future JWST observations of PNe providing unique insight into fundamental astrophysical processes including colliding winds, and binary star interactions, with implications for supernovae and gravitational wave systems.

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