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Because the galaxies of the Local Group have such large angular sizes, much of their diffuse, large-angular-scale emission is filtered out by the Herschel data reduction process. In this work, we restore this previously missed dust in Herschel observations of the Large Magellanic Cloud, Small Magellanic Cloud, M31, and M33. We do this by combining Herschel data (including new reductions for the Magellanic Clouds), in Fourier space, with lower-resolution data from all-sky surveys (Planck, IRAS, and COBE) that did not miss the extended emission. With these new maps, we find that a significant amount of emission was missing from uncorrected Herschel data of these galaxies; over 20% in some bands. Our new photometry also resolves the disagreement between fluxes reported from older HERITAGE Magellanic Cloud Herschel reductions, and fluxes reported from other telescopes. More emission is restored in shorter wavelength bands, especially in the galaxies' peripheries, making these regions 20-40% bluer than before. We also find that the Herschel-PACS instrument response conflicts with the all-sky data, over the 20-90' angular scales to which they are both sensitive, by up to 31%. By binning our new data based on hydrogen column density, we are able to detect emission from dust at low ISM densities (at $\Sigma_{\rm H} < 1\,{\rm M_{\odot} pc^{-2}}$ in some cases), and are able to detect emission at much lower densities (a factor of 2.2 lower on average, and more than a factor of 7 lower in several cases) than was possible with uncorrected data., Comment: Accepted for publication in ApJ

We assemble a catalogue of Magellanic Cloud red giants from Data Release 2 of the $Gaia$ mission and, utilising machine learning methods, obtain photometric metallicity estimates for them. In doing so, we are able to chemically map the entirety of the Magellanic System at once. Our high resolution maps reveal a plethora of substructure, with the Large Magellanic Cloud (LMC) bar and spiral arm being readily apparent. We uncover a curious spiral-like feature in the southern portion of the LMC disc, hosting relatively metal-rich giants and likely a by-product of historic encounter with the Small Magellanic Cloud (SMC). Modelling the LMC as an inclined thin disc, we find a shallow metallicity gradient of $-0.048 \pm 0.001$ dex/kpc out to $\sim 12^{\circ}$ from the centre of the dwarf. We see evidence that the Small Magellanic Cloud is disrupting, with its outer iso-density contours displaying the S-shape symptomatic of tidal stripping. On studying the proper motions of the SMC giants, we observe a population of them being violently dragged towards the larger Cloud. The perturbed stars predominately lie in front of the SMC, and we interpret that they exist as a tidal tail of the dwarf, trailing in its motion and undergoing severe disruption from the LMC. We find the metallicity structure in the Magellanic Bridge region to be complex, with evidence for a composite nature in this stellar population, consisting of both LMC and SMC debris., MNRAS, submitted

We use a Monte Carlo radiative transfer model (MCRTM) to simulate the UBVRI light curves, images and linear polarization of a light echo from supernova SN$~$1987A in the Large Magellanic Cloud (LMC) using various dust cloud shapes, sizes, and optical properties. We compare the theoretical simulations to the observations of AT2019xis, a light echo detected at a large angular distance (4.05$^{'}$) from SN$~$1987A. We estimate the size and optical thickness of the dust cloud based on the simulation results and the observations of Optical Gravitational Lensing Experiment (OGLE-IV) Transient Detection System (OTDS) I-band light curve. The mass of the dust cloud is calculated using the estimated size, optical thickness and extinction coefficient. If the dust cloud is assumed to correspond to a gas-to-dust ratio of 300, the total mass of the dust cloud is approximately 7.8-9.3 $M_{\odot}$. Based on these theoretical models, we show that the morphological shapes of the light echoes in the wavelength range in or shorter than the U-band to be very different from those in the longer wavelength bands, and the difference carries important information on the early UV radiation of SN$~$1987A., Comment: 21 pages, 20 figures, accepted to ApJ. Corrected several typos

We present the mid-infrared (mid-IR) period$-$luminosity relations (PLRs) using over 1000 Mira variables in the Large Magellanic Cloud (LMC), for the four Wide-Field Infrared Survey Explorer (WISE) and the four Spitzer bands. These PLRs cover a mid-IR wavelength range from $3.4$ $\mu$m to $22$ $\mu$m and are presented separately for the oxygen-rich (O-rich) and carbon-rich (C-rich) Miras. These relations can be used to measure distances to individual O-rich and/or C-rich Mira stars with the accuracy of $5\%$ and $12\%$, respectively. They are the most accurate Mira PLRs in the mid-IR to date., Comment: Accepted for publication in The Astrophysical Journal. 18 pages, 8 figures, 4 tables. The full machine readable Table 3 will be available in the online journal just after publication

The Molecular Ridge in the LMC extends several kiloparsecs south from 30 Doradus, and it contains ~30% of the molecular gas in the entire galaxy. However, the southern end of the Molecular Ridge is quiescent - it contains almost no massive star formation, which is a dramatic decrease from the very active massive star-forming regions 30 Doradus, N159, and N160. We present new ALMA and APEX observations of the Molecular Ridge at a resolution as high as ~16'' (~3.9 pc) with molecular lines 12CO(1-0), 13CO(1-0), 12CO(2-1), 13CO(2-1), and CS(2-1). We analyze these emission lines with our new multi-line non-LTE fitting tool to produce maps of T_kin, n_H2, and N_CO across the region based on models from RADEX. Using simulated data for a range of parameter space for each of these variables, we evaluate how well our fitting method can recover these physical parameters for the given set of molecular lines. We then compare the results of this fitting with LTE and X_CO methods of obtaining mass estimates and how line ratios correspond with physical conditions. We find that this fitting tool allows us to more directly probe the physical conditions of the gas and estimate values of T_kin, n_H2, and N_CO that are less subject to the effects of optical depth and line-of-sight projection than previous methods. The fitted n_H2 values show a strong correlation with the presence of YSOs, and with the total and average mass of the associated YSOs. Typical star formation diagnostics, such as mean density, dense gas fraction, and virial parameter do not show a strong correlation with YSO properties., Accepted for publication in the Astrophysical Journal

Similarities in the chemical composition of two of the closest Milky Way satellites, namely the Large Magellanic Cloud (LMC) and the Sagittarius (Sgr) dwarf galaxy, have been proposed in the literature, suggesting similar chemical enrichment histories between the two galaxies. This proposition, however, rests on different abundance analyses, which likely introduce various systematics that hamper a fair comparison among the different data sets. In order to bypass this issue (and highlight real similarities and differences between their abundance patterns), we present a homogeneous chemical analysis of 30 giant stars in LMC, 14 giant stars in Sgr and 14 giants in the Milky Way, based on high-resolution spectra taken with the spectrograph UVES-FLAMES. The LMC and Sgr stars, in the considered metallicity range ([Fe/H]>-1.1 dex), show very similar abundance ratios for almost all the elements, with differences only in the heavy s-process elements Ba, La and Nd, suggesting a different contribution by asymptotic giant branch stars. On the other hand, the two galaxies have chemical patterns clearly different from those measured in the Galactic stars, especially for the elements produced by massive stars. This finding suggests the massive stars contributed less to the chemical enrichment of these galaxies with respect to the Milky Way. The derived abundances support similar chemical enrichment histories for the LMC and Sgr., 21 pages, 8 figures, Accepted for publication by ApJ

We derive the mass-radius relation and mass function of molecular clumps in the Large Magellanic Cloud (LMC) and interpret them in terms of the simple feedback model proposed by Fall, Krumholz, and Matzner (FKM). Our work utilizes the dendrogram-based catalog of clumps compiled by Wong et al. from $^{12}$CO and $^{13}$CO maps of six giant molecular clouds in the LMC observed with the Atacama Large Millimeter Array (ALMA). The Magellanic Clouds are the only external galaxies for which this type of analysis is possible at the necessary spatial resolution ($\sim1$ pc). We find that the mass-radius relation and mass function of LMC clumps have power-law forms, $R \propto M^{\alpha}$ and $dN/dM \propto M^{\beta}$, with indices $\alpha = 0.36 \pm 0.03$ and $\beta= -1.8 \pm 0.1 $ over the mass ranges $10^2 M_\odot \lesssim M \lesssim 10^5 M_\odot$ and $10^2 M_\odot \lesssim M \lesssim 10^4 M_\odot$, respectively. With these values of $\alpha$ and $\beta$ for the clumps (i.e., protoclusters), the predicted index for the mass function of young LMC clusters from the FKM model is $\beta \approx 1.7$, in good agreement with the observed index. The situation portrayed here for clumps and clusters in the LMC replicates that in the Milky Way., Comment: 18 pages, 5 figures; accepted for publication in the Astrophysical Journal

The geometric structure of supernova remnants (SNR) provides a clue to unveiling the pre-explosion evolution of their progenitors. Here we present an X-ray study of N103B (0509-68.7), a Type Ia SNR in the Large Magellanic Cloud, that is known to be interacting with dense circumstellar matter (CSM). Applying our novel method for feature extraction to deep Chandra observations, we have successfully resolved the CSM, Fe-rich ejecta, and intermediate-mass element (IME) ejecta components, and revealed each of their spatial distribution. Remarkably, the IME ejecta component exhibits a double-ring structure, implying that the SNR expands into an hourglass-shape cavity and thus forms bipolar bubbles of the ejecta. This interpretation is supported by more quantitative spectroscopy that reveals a clear bimodality in the distribution of the ionization state of the IME ejecta. These observational results can be naturally explained if the progenitor binary system had formed a dense CSM torus on the orbital plane prior to the explosion, providing further evidence that the SNR N103B originates from a single-degenerate progenitor., 12 pages, 12 figures, accepted for publication in ApJ Letters (originally submitted to ApJ, but offered a transfer to ApJL)

Recently, a noticeable number of new star clusters was identified in the outskirts of the Large Magellanic Cloud (LMC) populating the so-called star cluster age gap, a space of time (~ 4-12 Gyr) where the only known star cluster is up-to-date ESO121-SC\,03. We used Survey of the Magellanic Stellar History (SMASH) DR2 data sets, as well as those employed to identify these star cluster candidates, to produce relatively deep color-magnitude diagrams (CMDs) of 17 out of 20 discovered age gap star clusters with the aim of investigating them in detail. Our analysis relies on a thorough CMD cleaning procedure of the field star contamination, which presents variations in its stellar density and astrophysical properties, such as luminosity and effective temperature, around the star cluster fields. We built star cluster CMDs from stars with membership probabilities assigned from the cleaning procedure. These CMDs and their respective spatial distribution maps favor the existence of LMC star field density fluctuations rather than age gap star clusters, although a definitive assessment on them will be possible from further deeper photometry., Comment: 9 pages, 10 figures. Accepted for publication in The Astronomical Journal

We present a deep Hubble Space Telescope (HST) imaging study of two dwarf galaxies in the halos of Local Volume Large Magellanic Cloud (LMC) analogs. These dwarfs were discovered as part of our Subaru+Hyper Suprime-Cam MADCASH survey: MADCASH-1, which is a satellite of NGC 2403 (D~3.2 Mpc), and MADCASH-2, a previously unknown dwarf galaxy near NGC 4214 (D~3.0 Mpc). Our HST data reach >3.5 mag below the tip of the red giant branch (TRGB) of each dwarf, allowing us to derive their structural parameters and assess their stellar populations. We measure TRGB distances ($D=3.41^{+0.24}_{-0.23}$ Mpc for MADCASH-1, and $D=3.00^{+0.13}_{-0.15}$ Mpc for MADCASH-2), and confirm their associations with their host galaxies. MADCASH-1 is a predominantly old, metal-poor stellar system (age ~13.5 Gyr, [M/H] ~ -2.0), similar to many Local Group dwarfs. Modelling of MADCASH-2's CMD suggests that it contains mostly ancient, metal-poor stars (age ~13.5 Gyr, [M/H] ~ -2.0), but that ~10% of its stellar mass was formed 1.1--1.5 Gyr ago, and ~1% was formed 400--500 Myr ago. Given its recent star formation, we search MADCASH-2 for neutral hydrogen using the Green Bank Telescope, but find no emission and estimate an upper limit on the HI mass of $, 20 pages, 9 figures, 4 tables; minor edits to match accepted version published in ApJ

The Large Magellanic Cloud supernova remnant J0454-6713 abutting the H ii region N9 has been observed with XMM-Newton. Two groups of lines from Fe xvii account for half the emission and lines from Fe xviii, O vii, and O viii are also clearly detected with the XMM RGS. Isothermal equilibrium fits of the EPIC spectra reproduce the basic spectral form and show little variation throughout the remnant but are insensitive to the lines from the high-temperature ions. These are overwhelmed in the EPIC cameras by the dominant Fe xvii radiation and the EPIC best-fit spectra do not agree with the RGS data. Uncertainties in the atomic data used to determine Fe-line strength present a further complication which inhibits a good EPIC spectral fit. We build a two-temperature model which does fit both RGS and EPIC results and propose that the high-T component is from SN debris and the low from heated material in the H ii region. The high ratio of Fe emission to that from O requires the remnant to be the product of a Type Ia supernova and points to a deflagration–detonation origin. Weak X-ray emission from the N9 superbubble is detected and briefly discussed. The abundance of Ne in N9 material seems higher than average for the LMC in both the superbubble spectrum and the low-temperature component of the remnant RGS spectrum.

We present the first spectroscopically resolved \ha\ emission map of the Large Magellanic Cloud's (LMC) galactic wind. By combining new Wisconsin H-alpha Mapper (WHAM) observations ($I_{\rm H\alpha}\gtrsim10~{\rm mR}$) with existing \hicm\ emission observations, we have (1) mapped the LMC's near-side galactic wind over a local standard of rest (LSR) velocity range of $+50\le\rm v_{LSR}\le+250~{\rm km}~{\rm s}^{-1}$, (2) determined its morphology and extent, and (3) estimated its mass, outflow rate, and mass-loading factor. We observe \ha\ emission from this wind to typically 1-degree off the LMC's \hi\ disk. Kinematically, we find that the diffuse gas in the warm-ionized phase of this wind persists at both low ($\lesssim100~{\rm km}~{\rm s}^{-1}$) and high ($\gtrsim100~{\rm km}~{\rm s}^{-1}$) velocities, relative to the LMC's \hi\ disk. Furthermore, we find that the high-velocity component spatially aligns with the most intense star-forming region, 30~Doradus. We, therefore, conclude that this high-velocity material traces an active outflow. We estimate the mass of the warm ($T_e\approx10^4~\rm K$) ionized phase of the near-side LMC outflow to be $\log{\left(M_{\rm ionized}/M_\odot\right)=7.51\pm0.15}$ for the combined low and high velocity components. Assuming an ionization fraction of 75\% and that the wind is symmetrical about the LMC disk, we estimate that its total (neutral and ionized) mass is $\log{\left(M_{\rm total}/M_\odot\right)=7.93}$, its mass-flow rate is $\dot{M}_{\rm outflow}\approx1.43~M_\odot~\rm yr^{-1}$, and its mass-loading factor is $\eta\approx4.54$. Our average mass-loading factor results are roughly a factor of 2.5 larger than previous \ha\ imaging and UV~absorption line studies, suggesting that those studies are missing nearly half the gas in the outflows., Comment: 19 pages, 9 figures

Surveys of Wolf-Rayet (WR) stars in the Large Magellanic Cloud (LMC) have yielded a fairly complete catalog of 154 known stars. We have conducted a comprehensive, multiwavelength study of the interstellar/circumstellar environments of WR stars, using the Magellanic Cloud Emission Line Survey (MCELS) images in the H$\alpha$, [O III], and [S II] lines; Spitzer Space Telescope 8 and 24 $\mu$m images; Blanco 4m Telescope H$\alpha$ CCD images; and Australian Telescope Compact Array (ATCA) + Parkes Telescope H I data cube of the LMC. We have also examined whether the WR stars are in OB associations, classified the H II environments of WR stars, and used this information to qualitatively assess the WR stars' evolutionary stages. The 30 Dor giant H II region has active star formation and hosts young massive clusters, thus we have made statistical analyses for 30 Dor and the rest of the LMC both separately and altogether. Due to the presence of massive young clusters, the WR population in 30 Dor is quite different from that from elsewhere in the LMC. We find small bubbles ($, Comment: 32 pages, 5 figures, accepted for publication in The Astrophysical Journal Supplement Series

We constrain the global parameters of the Large Magellanic Cloud (LMC) by modeling the first soft X-ray (0.4–6.8 keV) observations of the entire LMC produced in a single pointing with moderate spectral resolution by the HaloSat CubeSat. These data are best fit with the sum of two thermal plasma components in collisional ionization equilibrium and a power law. We find cool (0.210 ± 0.014 keV) and hot (0.89 ± 0.14 keV) components. The total X-ray luminosity of the LMC is (1.08 ± 0.14) × 1039 erg s−1. X-ray binaries make up a large fraction of the emission with a luminosity of (6.0 ± 0.8) × 1038 erg s−1, followed by cool gas from superbubbles, supernovae, and diffuse emission with a luminosity of (3.0 ± 0.3) × 1038 erg s−1. The hot gas from star formation contributes the smallest fraction, with a luminosity of (1.9 ± 0.5) × 1038 erg s−1. We estimate the total volume of the cool gas to be between (0.2–1.2) × 1010 pc3 and the hot gas to be between (1.0–5) × 107 pc3 for filling factors of f = 1 and 0.2. These volumes result in a total thermal energy for the cool gas between (1.4–3) × 1054 erg for electron densities of 0.017–0.04 cm−3, and a thermal energy for the hot gas between (1.7–4) × 1053 erg for electron densities of 0.12–0.3 cm−3. This yields cooling timescales for the cool and hot gas of (1.5–3) × 108 yr and (1.8–6) × 107 yr, respectively.

We present the results of high spatial resolution HCO$^{+}$($1-0$) and HCN($1-0$) observations of N55 south region (N55-S) in the Large Magellanic Cloud (LMC), obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). N55-S is a relatively less extreme star-forming region of the LMC characterized by a low radiation field. We carried out a detailed analysis of the molecular emission to investigate the relation between dense molecular clumps and star formation in the quiescent environment of N55-S. We detect ten molecular clumps with significant HCO$^{+}(1-0)$ emission and eight with significant HCN($1-0$) emission, and estimate the molecular clump masses by virial and local thermodynamic equilibrium analysis. All identified young stellar objects (YSOs) in the N55-S are found to be near the HCO$^{+}$ and HCN emission peaks showing the association of these clumps with recent star formation activity. The molecular clumps that have associated YSOs show relatively larger linewidths and masses than those without YSOs. We compare the clump properties of the N55-S with those of other giant molecular clouds (GMCs) in the LMC and find that N55-S clumps possess similar size but relatively lower linewidth and larger HCN/HCO$^{+}$(1$-$0) flux ratio. These results can be attributed to the low radiation field in N55-S resulted by relatively low star formation activity compared to other active star-forming regions like 30Doradus-10 and N159. The dense gas fraction of N55-S is $\sim$ 0.025, lower compared to other GMCs of the LMC supporting the low star formation efficiency of this region., Accepted for publication in ApJ, 13 pages, 4 figures

Intrigued by the extended red-giant clump (RC) stretching across the colour-magnitude diagram of the stars in a 50x50 pc^2 region of the Large Magellanic Cloud (LMC) containing the clusters NGC 1938 and NGC 1939, we have studied the stellar populations to learn about the properties of the interstellar medium (ISM) in this area. The extended RC is caused by a large and uneven amount of extinction across the field. Its slope reveals anomalous extinction properties, with Av/E(B-V)=4.3, indicating the presence of an additional grey component in the optical contributing about 30% of the total extinction in the field and requiring big grains to be about twice as abundant as in the diffuse ISM. This appears to be consistent with the amount of big grains injected into the surrounding ISM by the about 70 SNII explosions estimated to have occurred during the lifetime of the ~120 Myr old NGC 1938. Although this cluster appears today relatively small and would be hard to detect beyond the distance of M 31, with an estimated initial mass of ~4800 Msun NGC 1938 appears to have seriously altered the extinction properties in a wide area. This has important implications for the interpretation of luminosities and masses of star-forming galaxies, both nearby and in the early universe., 8 pages, 4 figures, accepted for publication in The Astrophysical Journal

We present a three-dimensional kinematic reconstruction of the optically-emitting, oxygen-rich ejecta of supernova remnant N132D in the Large Magellanic Cloud. Data were obtained with the 6.5 m Magellan telescope in combination with the IMACS+GISMO instrument and survey [O III] $\lambda\lambda$4959,5007 line emission in a ${\sim}$3$^{\prime}~\times$ 3$^{\prime}$ region centered on N132D. The spatial and spectral resolution of our data enable detailed examination of the optical ejecta structure. The majority of N132D's optically bright oxygen ejecta are arranged in a torus-like geometry tilted approximately 28$^{\circ}$ with respect to the plane of the sky. The torus has a radius of 4.4 pc ($D_{\rm LMC}$/50 kpc), exhibits a blue-shifted radial velocity asymmetry of $-3000$ to $+2300$ km s$^{-1}$, and has a conspicuous break in its circumference. Assuming homologous expansion from the geometric center of O-rich filaments, the average expansion velocity of 1745 km s$^{-1}$ translates to an age since explosion of 2450 $\pm$ 195 yr. A faint, spatially-separated "runaway knot" (RK) with total space velocity of 3650 km s$^{-1}$ is nearly perpendicular to the torus plane and coincident with X-ray emission that is substantially enhanced in Si relative to the LMC and N132D's bulk ejecta. These kinematic and chemical signatures suggest that the RK may have had its origin deep within the progenitor star. Overall, the main shell morphology and high-velocity, Si-enriched components of N132D have remarkable similarity with that of Cassiopeia A, which was the result of a Type IIb supernova explosion. Our results underscore the need for further observations and simulations that can robustly reconcile whether the observed morphology is dominated by explosion dynamics or shaped by interaction with the environment., Comment: 18 pages, 12 figures, accepted for publication in ApJ; 3D animation of N132D can found at: http://www.physics.purdue.edu/kaboom/n132d-anim.mp4

We perform detailed spectroscopy of the X-ray brightest supernova remnant (SNR) in the Large Magellanic Cloud (LMC), N132D, using Chandra archival observations. By analyzing the spectra of the entire well-defined rim, we determine the mean abundances for O, Ne, Mg, Si, S and Fe for the local LMC environment. We find evidence of enhanced O on the north-western and S on the north-eastern blast wave. By analyzing spectra interior to the remnant, we confirm the presence of a Si-rich relatively hot plasma (> 1.5 kev) that is also responsible for the Fe K emission. Chandra images show that the Fe K emission is distributed throughout the interior of the southern half of the remnant but does not extend out to the blast wave. We estimate the progenitor mass to be $15\pm5\,M_{\odot}$ using abundance ratios in different regions that collectively cover a large fraction of the remnant, as well as from the radius of the forward shock compared with models of an explosion in a cavity created by stellar winds. We fit ionizing and recombining plasma models to the Fe K emission and find that the current data cannot distinguish between the two, hence the origin of the high-temperature plasma remains uncertain. Our analysis is consistent with N132D being the result of a core-collapse supernova in a cavity created by its intermediate mass progenitor., 32 pages, 28 figures, 10 tables, accepted for ApJ

Rotation and binary interaction play important roles in understanding the nature of massive stars (>8 Msun). Some interesting transients, such as the long-duration gamma-ray bursts, are thought to be originated from fast-rotating massive stars. Because the strong stellar wind can effectively spin down a metal-rich massive star with fast rotation, it is very hard to find single massive stars rotating critically in the Galaxy. In the present work reported is the discovery of the fastest rotator in the Galaxy, LAMOST J040643.69+542347.8, with a projected rotational velocity vsini ~540 km/s, which is ~ 100 km/s faster than that of the previous record holder HD 191423. The star has a spectral type of O6.5 Vnnn(f)p. Its He I 4471 absorption line is blueshifted and asymmetric, while its He II 4686 and Ha have central absorption reversals in their emissions. It is also a runaway star, which implies an origin in a close binary interaction. Compared to VFTS 285 and VFTS 102 (their vsini ~ 610 km/s) in the Large Magellanic Cloud, LAMOST J040643.69+542347.8 has its own peculiar spectral characteristics and earlier spectral type. Moreover, LAMOST J040643.69+542347.8 is bright (B ~ 13.9 mag) enough to allow future high-resolution spectroscopic follow-ups., 7 pages, 3 figures, 1 table. Accepted by the ApJ Letter