adsabs/AstroCLIMB huggingface dataset:
Paper: What Are the Radial Distributions of Density, Outflow Rates, and Cloud Structures in the M82 Wind?
Authors: Xinfeng Xu, Timothy Heckman, Michitoshi Yoshida, Alaina Henry, Youichi Ohyama
Figure caption: Comparisons of the semianalytic models by Fielding & Bryan (2022) with the derived outflow parameters in this paper. We have rerun their models to match the input parameters of M82 (i.e., SFR = 8 M ⊙ yr−1, starburst radius = 300 pc, and bipolar outflows with opening angle of 73.°7). The blue and red lines represent the models with initial hot phase mass-loading factor of 0.1 and 0.5, respectively. The former produces faster and less dense hot wind fluid (hereafter FW model), while the latter generates slower and denser wind fluid (hereafter SW model). The solid and dashed lines represent different outflow cloud mass into the models, i.e., 101 and 106 M ⊙, respectively. In the four panels, we show the model-predicted outflow cloud velocity (top left), mass (top right), energy (bottom left), and momentum outflow rate (bottom right). In each panel, we overlay our observed outflow properties from Hα as black dotted lines with error bars. We discuss these comparisons in detail in Section 4.4.
Paper: What Are the Radial Distributions of Density, Outflow Rates, and Cloud Structures in the M82 Wind?
Authors: Xinfeng Xu, Timothy Heckman, Michitoshi Yoshida, Alaina Henry, Youichi Ohyama
Figure caption: Subaru/FOCAS image of Hα +[N II] emission lines (with continuum already subtracted; see Section 2.1). The galaxy disk (white dashed line) has been rotated to be parallel with the x-axis, so the bipolar galactic outflow is perpendicular to the galactic disk (northwest side is up). We overlay the position of FOCAS spectroscopic observations described in Yoshida et al. (2019) as red circles (Section 2.2).
Paper: What Are the Radial Distributions of Density, Outflow Rates, and Cloud Structures in the M82 Wind?
Authors: Xinfeng Xu, Timothy Heckman, Michitoshi Yoshida, Alaina Henry, Youichi Ohyama
Figure caption: Top left: radial distribution of the volume filling factor (FF) derived from the Hα and [S II] emission lines. The best-fit power law is shown as the blue dashed line. Top right: the black line represents the radial distribution of mass outflow rates (﹩{\dot{M}}_{\mathrm{out}}﹩) derived in Section 3.3. The blue line represents the deprojected outflow velocity (V out) from Hα(Shopbell & Bland-Hawthorn 1998). Bottom: kinetic energy and momentum outflow rates derived in Section 3.3.
Paper: What Are the Radial Distributions of Density, Outflow Rates, and Cloud Structures in the M82 Wind?
Authors: Xinfeng Xu, Timothy Heckman, Michitoshi Yoshida, Alaina Henry, Youichi Ohyama
Figure caption: Left: the cumulative counts of Hα from Subaru FOCAS image (see Figure 1 and Section 3.2). The two blue dashed lines represent the locations where the cumulative counts equal 10% and 90% of the total counts, separately. We define the outflow width as the region between the blue dashed lines, which is 1.8 kpc for this radial bin. Right: outflow width distribution among different radial distances to the galactic center of M82 (r).
Paper: What Are the Radial Distributions of Density, Outflow Rates, and Cloud Structures in the M82 Wind?
Authors: Xinfeng Xu, Timothy Heckman, Michitoshi Yoshida, Alaina Henry, Youichi Ohyama
Figure caption: The log of the outflow velocity (V out) vs. circular velocity (left) and SFR (right). Galaxies from the CLASSY sample are shown in black, while measurements for in M82 in this paper are shown as the red star. Orange dashed lines represent the best-fit linear correlation presented in Xu et al. (2022). In general, the galactic winds in M82 match the scaling relationships reported for low-redshift SF galaxies in CLASSY.
Paper: What Are the Radial Distributions of Density, Outflow Rates, and Cloud Structures in the M82 Wind?
Authors: Xinfeng Xu, Timothy Heckman, Michitoshi Yoshida, Alaina Henry, Youichi Ohyama
Figure caption: Top: correlations related to the mass-loading factor (﹩{\dot{M}}_{\mathrm{out}}﹩/SFR). Labels and captions are the same as in Figure 5. Bottom: correlations of the momentum (energy) outflow rates vs. momentum (energy) supplied by the starburst. See discussion in Section 4.2.
Paper: What Are the Radial Distributions of Density, Outflow Rates, and Cloud Structures in the M82 Wind?
Authors: Xinfeng Xu, Timothy Heckman, Michitoshi Yoshida, Alaina Henry, Youichi Ohyama
Figure caption: Left: radial distribution of the outflow cloud sizes. Right: radial distribution of the cloud hydrogen column density (N H,cl) for the outflows. See Section 4.3 for details.
Paper: Abundances and Transients from Neutron Star–White Dwarf Mergers
Authors: M. Alexander R. Kaltenborn, Chris L. Fryer, Ryan T. Wollaeger, Krzysztof Belczynski, Wesley Even, Chryssa Kouveliotou
Figure caption: The differences among the three classes of simulations for the accretion rate through the inner boundary (left panel) and for the wind-ejection radial profile (right panel). Here we specifically show the M NS–M WD 1.25–1.00 binary for each class. The accretion rate through the inner boundary is extrapolated to late times with a power-law fit.
Paper: Abundances and Transients from Neutron Star–White Dwarf Mergers
Authors: M. Alexander R. Kaltenborn, Chris L. Fryer, Ryan T. Wollaeger, Krzysztof Belczynski, Wesley Even, Chryssa Kouveliotou
Figure caption: Top left panel: initial WD mass 0.50 M ⊙: CEEW02. Top right panel: initial WD mass 0.75 M ⊙: CEEW04. Bottom left panel: initial WD mass 1.00 M ⊙: CEEW07. Bottom right panel: initial WD mass 1.25 M ⊙: CEEW11. All companion NSs are 1.25 M ⊙. Here the midline nuclear abundances are at roughly t = 5 s.
Paper: Abundances and Transients from Neutron Star–White Dwarf Mergers
Authors: M. Alexander R. Kaltenborn, Chris L. Fryer, Ryan T. Wollaeger, Krzysztof Belczynski, Wesley Even, Chryssa Kouveliotou
Figure caption: The different profiles for entropy for a 1.25 M ⊙ NS and 1.00 M ⊙ WD binary. The prescription is specified by the subscripts, 1–3. These refer to Equations (5)–(7), respectively. For prescription 1, the entropy of the material is high in the inner and outer regions, dipping to its lowest point around 109 cm. For prescription 2, the entropy decreases by 1 order of magnitude in the inner region; however, the middle and outer regions (where the bulk of the WD matter is) still have high entropies. There is a region where the entropies are higher than in prescription 1. Prescription 3 can be tuned to have a desired entropy, and scaled as necessary, although here, the entropy is assigned to be a constant. The temperatures are normalized to the maximum from prescription 1, ﹩{T}_{\max }=100﹩. The density profile is the same for each prescription, normalized to ﹩{\rho }_{\max }=100﹩.
Paper: Abundances and Transients from Neutron Star–White Dwarf Mergers
Authors: M. Alexander R. Kaltenborn, Chris L. Fryer, Ryan T. Wollaeger, Krzysztof Belczynski, Wesley Even, Chryssa Kouveliotou
Figure caption: Top left panel: initial WD mass 0.50 M ⊙: CEEW02. Top right panel: initial WD mass 0.75 M ⊙: CEEW04. Bottom left panel: initial WD mass 1.00 M ⊙: CEEW07. Bottom right panel: initial WD mass 1.25 M ⊙: CEEW11. All companion NSs are 1.25 M ⊙. Here we have the wind-ejecta nuclear abundances. The abundances are grouped by ejection velocity and summed over the entirety of the simulation, about 60 s. When looking at the distribution of isotopes in the wind, we find that the fastest-moving material in the ejecta is composed primarily of 4He, 54,56Fe, and 56Ni.
Paper: Abundances and Transients from Neutron Star–White Dwarf Mergers
Authors: M. Alexander R. Kaltenborn, Chris L. Fryer, Ryan T. Wollaeger, Krzysztof Belczynski, Wesley Even, Chryssa Kouveliotou
Figure caption: Top left panel: initial NS mass 1.10 M ⊙, i.e., models CEEW01, CEEW03, CEEW06, and CEEW10. Top right panel: initial NS mass 1.25 M ⊙: CEEW02, CEEW04, CEEW07, and CEEW11. Bottom left panel: initial NS mass 1.40 M ⊙: CEEW05, CEEW08, and CEEW12. Bottom right panel: initial NS mass 1.80 M ⊙: CEEW09 and CEEW13. We have plotted the wind abundances for each configuration. Using the 21-isotope nuclear network, we highlight a subset of the available isotopes. Of particular interest are the abundances of 44Ti, 56Fe, and 56Ni found in the ejecta.
Paper: Abundances and Transients from Neutron Star–White Dwarf Mergers
Authors: M. Alexander R. Kaltenborn, Chris L. Fryer, Ryan T. Wollaeger, Krzysztof Belczynski, Wesley Even, Chryssa Kouveliotou
Figure caption: The demographics ensued from running the StarTrack code and collecting the NS–WD binaries. The top left panel shows a heat map of NS–WD binary mass components with different colors representing the dominant nuclear composition. The bottom left panel shows the absolute mass distribution for all WDs and NSs irrespective of their companion. On the right, we show the WD mass distribution for select NS masses where we find peaks in the distribution, M NS = 1.11 and 1.26, and an island of binaries centered around 1.82 M ⊙.
Paper: Abundances and Transients from Neutron Star–White Dwarf Mergers
Authors: M. Alexander R. Kaltenborn, Chris L. Fryer, Ryan T. Wollaeger, Krzysztof Belczynski, Wesley Even, Chryssa Kouveliotou
Figure caption: Examining models CEEW02, CEEW04, and CEEW07, we present (left panel) the nuclear heating rate at 6 s, normalized to the viscous heating rate for each model, and (right panel) the normalized nuclear heating rate to the viscous heating rate for the leading carbon-burning front over the duration of the evolution. We observe that nuclear heating rate peaks are in sync with the carbon-burning front at larger radii, with an additional bump associated with the oxygen-burning front. The carbon-burning front robustly heats the disk material at early stages (i.e., t < 1 s), which is followed by a second wave of intense combustion.
Paper: Abundances and Transients from Neutron Star–White Dwarf Mergers
Authors: M. Alexander R. Kaltenborn, Chris L. Fryer, Ryan T. Wollaeger, Krzysztof Belczynski, Wesley Even, Chryssa Kouveliotou
Figure caption: We show contour plots of the mass fractions of 28Si and 56Ni (﹩{\mathrm{log}}_{10}({X}_{\mathrm{ion}})﹩), plotting radius (﹩{\mathrm{log}}_{10}(r)﹩) and time (﹩{\mathrm{log}}_{10}(t)﹩). We show models CEEW02 (left panel) and CEEW07 (right panel). The burning fronts for Si and Ni follow a self-similar pattern, extending to the largest radius at times t peak, and then receding at later times.
Paper: Abundances and Transients from Neutron Star–White Dwarf Mergers
Authors: M. Alexander R. Kaltenborn, Chris L. Fryer, Ryan T. Wollaeger, Krzysztof Belczynski, Wesley Even, Chryssa Kouveliotou
Figure caption: We compare the wind ejecta composition for the same initial binary compositions for HENW, CENW, and CEEW. Left panel: HENW07, middle panel: CENW07, and right panel: CEEW07.
Paper: The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. I. Detection of a Rich Population of Dusty Objects in the IRS 13 Cluster
Authors: Florian Peißker, Michal Zajaček, Lauritz Thomkins, Andreas Eckart, Lucas Labadie, Vladimír Karas, Nadeen B. Sabha, Lukas Steiniger, Maria Melamed
Figure caption: Color–color diagram for some prominent stellar objects in the inner parsec. The linear gray line represents a one-component blackbody with increasing temperature and separates known evolved and embedded early-type stars from candidate YSOs (see also Ishii et al. 1998; Eckart et al. 2004). Based on this classification, the photometric data imply two generations of dusty sources, namely YSOs (brown) and main-sequence stars (yellow). Please note that the photometric uncertainty of two DS, DS23 and DS30, forbids a strong statement about their exact nature. Overall, the uncertainties represent the standard deviation of the estimated colors listed in Table 6. Here, IRS 16 refers to the stars indicated in Figure 3.
Paper: The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. I. Detection of a Rich Population of Dusty Objects in the IRS 13 Cluster
Authors: Florian Peißker, Michal Zajaček, Lauritz Thomkins, Andreas Eckart, Lucas Labadie, Vladimír Karas, Nadeen B. Sabha, Lukas Steiniger, Maria Melamed
Figure caption: Best-fit SED of the brightest dusty sources in the IRS 13 cluster representing the YSO parameters given in Table 8. The input spectrum is constructed using the flux density values listed in Tables 6 and 7. The associated numerical flux density values, including their related uncertainty, are implemented in the SED plots to emphasize the validity of the resulting best-fit parameters. For almost every source, the solution in magenta represents the best fit and is associated with an inclination of about 90°, while the gray SED is related to the maximum and minimum uncertainty indicated in Table 8. The inclination for the SED, including the related uncertainties of the source η, equals 70°.
Paper: The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. I. Detection of a Rich Population of Dusty Objects in the IRS 13 Cluster
Authors: Florian Peißker, Michal Zajaček, Lauritz Thomkins, Andreas Eckart, Lucas Labadie, Vladimír Karas, Nadeen B. Sabha, Lukas Steiniger, Maria Melamed
Figure caption: Normalized angular momentum j as a function of distance from Sgr A* for all the here investigated IRS 13 cluster members. We find a stellar distribution similar to the one derived by Paumard et al. (2006) for the majority of the NSC stars (see also von Fellenberg et al. 2022). Here, most of the investigated objects peak at j = −1, suggesting a CCW disk membership. Magenta circles represent the dusty sources analyzed in this work; the gold-filled ones indicate the E stars (Figure 3). The size of the individual data points covers up the uncertainties calculated with error propagation.
Paper: The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. I. Detection of a Rich Population of Dusty Objects in the IRS 13 Cluster
Authors: Florian Peißker, Michal Zajaček, Lauritz Thomkins, Andreas Eckart, Lucas Labadie, Vladimír Karas, Nadeen B. Sabha, Lukas Steiniger, Maria Melamed
Figure caption:  L-band NACO observation of IRS 13 in 2004 overlaid with [Fe III] 2.218 μm 3 G 5→3 H 6 contour lines extracted from a SINFONI 3D data cube. The contour lines represent the 26%, 30%, 40%, 50%, 60%, and 70% levels, whereas the peak emission is at 2.5 × 10−10ergs−1cm−2 μm−1. The 70% contour line centered on the core region of IRS 13 resembles the projected size of the Hill radius (≈22m pc) estimated with Equation (7) in Section 3.2. In addition, the 30% contour lines enclose the southern region with respect to the core and tip components of the IRS 13 cluster. As indicated, we mark the two embedded sources, IRS 2L and IRS 2S, that might be former members of the core region of IRS 13. The compact source IRS 2C is also known as AF/AHH (Allen et al. 1990; Blum et al. 1996) and could be a foreground star based on the polarimetric analysis of Buchholz et al. (2013).
Paper: The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. I. Detection of a Rich Population of Dusty Objects in the IRS 13 Cluster
Authors: Florian Peißker, Michal Zajaček, Lauritz Thomkins, Andreas Eckart, Lucas Labadie, Vladimír Karas, Nadeen B. Sabha, Lukas Steiniger, Maria Melamed
Figure caption:  J-band observation of IRS 13 with NACO in 2013. We overlaid lime-colored contour lines adopted from the K-band observations of the same epoch and instrument. The contour levels represent 0.75%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10% of the normalized K-band NACO data. The faint emission of IRS 2L is labeled at the corresponding K- and L-band position, whereas the bright emission is associated with IRS 13. We further indicate the position of the low-mass class I YSO η. Here, north is up, and east is to the left.
Paper: The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. I. Detection of a Rich Population of Dusty Objects in the IRS 13 Cluster
Authors: Florian Peißker, Michal Zajaček, Lauritz Thomkins, Andreas Eckart, Lucas Labadie, Vladimír Karas, Nadeen B. Sabha, Lukas Steiniger, Maria Melamed
Figure caption: Comparison of different input parameters for the flux density values (orange-colored dots) estimated for IRS 3 (Table 6). Please note that the magenta- and brown-colored SED is based on the stellar parameters derived by the interferometric broadband analysis by Pott et al. (2008). Assuming a hypothetical YSO association with IRS 3 results in unsatisfying outcomes of the radiative transfer model fit. Only a speculative stellar temperature of 1.9 × 105 K seems to reproduce the NIR and MIR flux. The submm/radio emission is not fitted by any of the presented SED solutions. Please see the text for details.
Paper: The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. I. Detection of a Rich Population of Dusty Objects in the IRS 13 Cluster
Authors: Florian Peißker, Michal Zajaček, Lauritz Thomkins, Andreas Eckart, Lucas Labadie, Vladimír Karas, Nadeen B. Sabha, Lukas Steiniger, Maria Melamed
Figure caption: Observation of the IRS 13 cluster with ALMA. The data were observed at 343 GHz and correspond to CO (v = 0). The location of the bright dusty sources that are observed in the infrared is indicated by colored circles. Like the E stars, the projected location of the dusty sources implies clustering. The related flux of the individual sources in listed in Table 7.
Paper: The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. I. Detection of a Rich Population of Dusty Objects in the IRS 13 Cluster
Authors: Florian Peißker, Michal Zajaček, Lauritz Thomkins, Andreas Eckart, Lucas Labadie, Vladimír Karas, Nadeen B. Sabha, Lukas Steiniger, Maria Melamed
Figure caption: NIRSPEC spectrum of the inner parsec observed with the James Webb Space Telescope in 2022 (PI: Jessica Lu, Proposal ID: 1939). The NIRSPEC observation agrees with the water ice identification by, e.g., Moultaka et al. (2015). Around 2.4μm, the detector gap of NIRSPEC is marked.
Paper: The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. I. Detection of a Rich Population of Dusty Objects in the IRS 13 Cluster
Authors: Florian Peißker, Michal Zajaček, Lauritz Thomkins, Andreas Eckart, Lucas Labadie, Vladimír Karas, Nadeen B. Sabha, Lukas Steiniger, Maria Melamed
Figure caption:  K-band observation of IRS 13 in 2009.
Paper: Forming Gas Giants around a Range of Protostellar M-dwarfs by Gas Disk Gravitational Instability
Authors: Alan P. Boss, Shubham Kanodia
Figure caption: Gas giant exoplanet formation frequency by GDGI as a function of M star mass and protoplanetary disk mass. Disk masses of ∼0.02M ⊙ or higher appear to be required for the GDGI to produce gas giant protoplanets. The histogram on the right shows the distribution of Class 0/I disk masses (gas + dust) as measured by VLA for ∼100 disks in Perseus (Tychoniec et al. 2018). We note the caveat that this sample consists of embedded protostellar FGKM sources, and is therefore likely biased to have a higher median disk mass than an M-dwarf-only sample. However, given the difficulty in estimating host stellar masses for embedded protostellar disks, such an M-dwarf-only protostellar sample does not currently exist.
Paper: Forming Gas Giants around a Range of Protostellar M-dwarfs by Gas Disk Gravitational Instability
Authors: Alan P. Boss, Shubham Kanodia
Figure caption: Gas giant exoplanet formation frequency by GDGI as a function of M star mass and protoplanetary disk-to-star mass ratio.
Paper: Forming Gas Giants around a Range of Protostellar M-dwarfs by Gas Disk Gravitational Instability
Authors: Alan P. Boss, Shubham Kanodia
Figure caption: Dependence of gas giant protoplanet formation by GDGI on M-dwarf stellar mass, disk mass, and outer disk temperatures for the 162 models in Tables 1 through 5.
Paper: Forming Gas Giants around a Range of Protostellar M-dwarfs by Gas Disk Gravitational Instability
Authors: Alan P. Boss, Shubham Kanodia
Figure caption: Planetary mass plotted as a function of stellar mass for GEMS. The transiting planets have true mass measurements, whereas M  p  sin i is plotted for the nontransiting ones, with the exception of GJ 463 b, which has a true mass measurement of ∼1140 M ⊕ from astrometry (Sozzetti et al. 2023).
Paper: Forming Gas Giants around a Range of Protostellar M-dwarfs by Gas Disk Gravitational Instability
Authors: Alan P. Boss, Shubham Kanodia
Figure caption: Gas giant exoplanet masses as a function of the outer disk temperatures for the 162 models in Tables 1 through 5.
Paper: Forming Gas Giants around a Range of Protostellar M-dwarfs by Gas Disk Gravitational Instability
Authors: Alan P. Boss, Shubham Kanodia
Figure caption: Gas giant exoplanet masses as a function of the disk masses for the 162 models in Tables 1 through 5.
Paper: Left Ringing: Betelgeuse Illuminates the Connection between Convective Outbursts, Mode Switching, and Mass Ejection in Red Supergiants
Authors: Morgan MacLeod, Andrea Antoni, Caroline D. Huang, Andrea Dupree, Abraham Loeb
Figure caption: Numerical tests. Left: comparison of identical initial conditions run at two resolutions. Our fiducial, higher-resolution model has nested meshes each with 2563 zones and is shown with thicker lines, while a factor of 2 lower-resolution case (nested meshes of 1283 zones) is shown with thinner lines. We find good agreement with the behavior of the models near peak, but find that the power in the lower-resolution model plateaus at slightly higher levels. This indicates to us that the decay rate of the l ≤ 8 power for the first ∼800 days is not sensitive to the spatial resolution. Right: comparison between two 1283 resolution runs with differing cooling. The thicker lines in this panel are the same as the left panel. The thinner lines are a model with more rapid cooling, evaluated at its own effective radius of 6r 0 in code units. We note that the small-scale power (l > 8) is higher when the cooling is more efficient. However, the large-scale modes (l ≤ 8) are largely insensitive to the cooling approximation, just as found in terms of spatial resolution.
Paper: An Optically Discovered Outburst from XTE J1859+226
Authors: Eric C. Bellm, Yuankun Wang, Jan van Roestel, Rebecca A. Phillipson, Michael W. Coughlin, John A. Tomsick, Steven L. Groom, Brian Healy, Josiah Purdum, Ben Rusholme, Jesper Sollerman, Peter Bealo, Stefano Lora, Eddy Muyllaert, Ivo Peretto, Erik J. Schwendeman
Figure caption: Outburst light curve for XTE J1859+226 from ZTF, P60, AAVSO, and Swift-UVOT and XRT. Detections (S/N > 3) are marked with points; 5σ upper limits are denoted with triangles. Text labels indicate the times of SEDM spectroscopy (S), NuSTAR observations (N), and Keck-LRIS spectroscopy (L).(The data used to create this figure are available.)
Paper: Left Ringing: Betelgeuse Illuminates the Connection between Convective Outbursts, Mode Switching, and Mass Ejection in Red Supergiants
Authors: Morgan MacLeod, Andrea Antoni, Caroline D. Huang, Andrea Dupree, Abraham Loeb
Figure caption: Eigenfunctions of radial (l = 0) and nonradial (l ≥ 1) modes, classified by n  pg . The fundamental mode’s eigenfunction is monotonic, while the overtones exhibit increasing numbers of radial nodes.
Paper: Left Ringing: Betelgeuse Illuminates the Connection between Convective Outbursts, Mode Switching, and Mass Ejection in Red Supergiants
Authors: Morgan MacLeod, Andrea Antoni, Caroline D. Huang, Andrea Dupree, Abraham Loeb
Figure caption: Slices through the computational domain of radial velocity relative to the stellar center, similar to Figure 2. In this case, the hot fluid contains the same total energy as in the fiducial model but is located deeper in the envelope at (x, y) = ( + 96 R ⊙, 0). Note that these panels have a shorter timescale and more extended velocity scale than Figure 2. The deeper-initialized disturbance launches a wave that accelerates down the density gradient of the stellar envelope, steepening into a strong shock that spans a full stellar hemisphere when it breaks out.