adsabs/AstroCLIMB huggingface dataset:
Paper: Simulation of Head-on Collisions between Filamentary Molecular Clouds Threaded by a Lateral Magnetic Field and Subsequent Evolution
Authors: Raiga Kashiwagi, Kazunari Iwasaki, Kohji Tomisaka
Figure caption: An example of the initial conditions: the density and magnetic field lines of the initial condition of the model β01M are plotted (see Table 2). Two identical filaments in magnetohydrostatic equilibrium are placed close to each other. These filaments have initial velocities of V 0 and −V 0. White lines represent the magnetic field lines. The external medium is shown in black.
Paper: A Tale of Two Disks: Mapping the Milky Way with the Final Data Release of APOGEE
Authors: Julie Imig, Cathryn Price, Jon A. Holtzman, Alexander Stone-Martinez, Steven R. Majewski, David H. Weinberg, Jennifer A. Johnson, Carlos Allende Prieto, Rachael L. Beaton, Timothy C. Beers, Dmitry Bizyaev, Michael R. Blanton, Joel R. Brownstein, Katia Cunha, José G. Fernández-Trincado, Diane K. Feuillet, Sten Hasselquist, Christian R. Hayes, Henrik Jönsson, Richard R. Lane, Jianhui Lian, Szabolcs Mészáros, David L. Nidever, Annie C. Robin, Matthew Shetrone, Verne Smith, John C. Wilson
Figure caption: Systematic uncertainties in the stellar age estimates, comparing the distmass (green and blue) and astroNN (red) catalogs across different ranges of stellar ﹩\mathrm{log}g﹩ (different panels). In each panel, the x-axis is the stellar age from asteroseismology estimates (APOKASC), and the y-axis is the predicted age recovered from the neural network methodology. The typical uncertainty of each point is depicted in black in the upper-left corner of each panel, with the asteroseismic measurements notably having larger uncertainties at lower ﹩\mathrm{log}g﹩. In both catalogs and across all ﹩\mathrm{log}g﹩, young stars are generally recovered too old, and old stars are recovered too young. However, there are higher uncertainties in the asteroseismic measurements for the low-﹩\mathrm{log}g﹩ stars, meaning the neural network age estimates may be more precise than the asteroseismic age estimates in this range.
Paper: A Tale of Two Disks: Mapping the Milky Way with the Final Data Release of APOGEE
Authors: Julie Imig, Cathryn Price, Jon A. Holtzman, Alexander Stone-Martinez, Steven R. Majewski, David H. Weinberg, Jennifer A. Johnson, Carlos Allende Prieto, Rachael L. Beaton, Timothy C. Beers, Dmitry Bizyaev, Michael R. Blanton, Joel R. Brownstein, Katia Cunha, José G. Fernández-Trincado, Diane K. Feuillet, Sten Hasselquist, Christian R. Hayes, Henrik Jönsson, Richard R. Lane, Jianhui Lian, Szabolcs Mészáros, David L. Nidever, Annie C. Robin, Matthew Shetrone, Verne Smith, John C. Wilson
Figure caption: Reproduction of the age–α relation (Figure 25) using different samples of stellar ages.
Paper: A Tale of Two Disks: Mapping the Milky Way with the Final Data Release of APOGEE
Authors: Julie Imig, Cathryn Price, Jon A. Holtzman, Alexander Stone-Martinez, Steven R. Majewski, David H. Weinberg, Jennifer A. Johnson, Carlos Allende Prieto, Rachael L. Beaton, Timothy C. Beers, Dmitry Bizyaev, Michael R. Blanton, Joel R. Brownstein, Katia Cunha, José G. Fernández-Trincado, Diane K. Feuillet, Sten Hasselquist, Christian R. Hayes, Henrik Jönsson, Richard R. Lane, Jianhui Lian, Szabolcs Mészáros, David L. Nidever, Annie C. Robin, Matthew Shetrone, Verne Smith, John C. Wilson
Figure caption: The same as Figure 2, but colored by the fraction of stars in our sample that survive the additional distmass quality cuts described in Section 2.4. The purpose of this figure is to qualitatively explore how the distmass criterion might bias our results using stellar age estimates.
Paper: A Tale of Two Disks: Mapping the Milky Way with the Final Data Release of APOGEE
Authors: Julie Imig, Cathryn Price, Jon A. Holtzman, Alexander Stone-Martinez, Steven R. Majewski, David H. Weinberg, Jennifer A. Johnson, Carlos Allende Prieto, Rachael L. Beaton, Timothy C. Beers, Dmitry Bizyaev, Michael R. Blanton, Joel R. Brownstein, Katia Cunha, José G. Fernández-Trincado, Diane K. Feuillet, Sten Hasselquist, Christian R. Hayes, Henrik Jönsson, Richard R. Lane, Jianhui Lian, Szabolcs Mészáros, David L. Nidever, Annie C. Robin, Matthew Shetrone, Verne Smith, John C. Wilson
Figure caption: The spatial distribution (X–Y face-on view) of stars in APOGEE for different bins of ﹩\mathrm{log}g﹩ (columns). Increasing the ﹩\mathrm{log}g﹩ range of our sample, which would minimize some of the age-related systematics, would also severely limit the area that our sample can probe.
Paper: A Tale of Two Disks: Mapping the Milky Way with the Final Data Release of APOGEE
Authors: Julie Imig, Cathryn Price, Jon A. Holtzman, Alexander Stone-Martinez, Steven R. Majewski, David H. Weinberg, Jennifer A. Johnson, Carlos Allende Prieto, Rachael L. Beaton, Timothy C. Beers, Dmitry Bizyaev, Michael R. Blanton, Joel R. Brownstein, Katia Cunha, José G. Fernández-Trincado, Diane K. Feuillet, Sten Hasselquist, Christian R. Hayes, Henrik Jönsson, Richard R. Lane, Jianhui Lian, Szabolcs Mészáros, David L. Nidever, Annie C. Robin, Matthew Shetrone, Verne Smith, John C. Wilson
Figure caption: Reproduction of the age–metallicity relation (Figure 23) using different samples of stellar ages.
Paper: A Tale of Two Disks: Mapping the Milky Way with the Final Data Release of APOGEE
Authors: Julie Imig, Cathryn Price, Jon A. Holtzman, Alexander Stone-Martinez, Steven R. Majewski, David H. Weinberg, Jennifer A. Johnson, Carlos Allende Prieto, Rachael L. Beaton, Timothy C. Beers, Dmitry Bizyaev, Michael R. Blanton, Joel R. Brownstein, Katia Cunha, José G. Fernández-Trincado, Diane K. Feuillet, Sten Hasselquist, Christian R. Hayes, Henrik Jönsson, Richard R. Lane, Jianhui Lian, Szabolcs Mészáros, David L. Nidever, Annie C. Robin, Matthew Shetrone, Verne Smith, John C. Wilson
Figure caption: Reproduction of the radial age gradients (Figure 20) using different samples of stellar ages.
Paper: FAST Drift Scan Survey for HI Intensity Mapping: I. Preliminary Data Analysis
Authors: Yichao Li, Yougang Wang, Furen Deng, Wenxiu Yang, Wenkai Hu, Diyang Liu, Xinyang Zhao, Shifan Zuo, Shuanghao Shu, Jixia Li, Peter Timbie, Réza Ansari, Olivier Perdereau, Albert Stebbins, Laura Wolz, Fengquan Wu, Xin Zhang, Xuelei Chen
Figure caption: The gain temporal variations of 4 hr observation. Each sub-panel shows the gain of one feed. The XX and YY polarizations are shown in red and blue colors, respectively. The dot markers represent the measurements with the noise diode; and the thick curves are the reconstructed gain variation.
Paper: FAST Drift Scan Survey for HI Intensity Mapping: I. Preliminary Data Analysis
Authors: Yichao Li, Yougang Wang, Furen Deng, Wenxiu Yang, Wenkai Hu, Diyang Liu, Xinyang Zhao, Shifan Zuo, Shuanghao Shu, Jixia Li, Peter Timbie, Réza Ansari, Olivier Perdereau, Albert Stebbins, Laura Wolz, Fengquan Wu, Xin Zhang, Xuelei Chen
Figure caption: The temporal power spectra of the time-ordered data. Each sub-panel shows the gain of one feed, the XX and YY polarizations are shown in red and blue colors. The dashed lines with markers show the measured power spectra and the solid lines show the best-fit model of Equation (17).
Paper: FAST Drift Scan Survey for HI Intensity Mapping: I. Preliminary Data Analysis
Authors: Yichao Li, Yougang Wang, Furen Deng, Wenxiu Yang, Wenkai Hu, Diyang Liu, Xinyang Zhao, Shifan Zuo, Shuanghao Shu, Jixia Li, Peter Timbie, Réza Ansari, Olivier Perdereau, Albert Stebbins, Laura Wolz, Fengquan Wu, Xin Zhang, Xuelei Chen
Figure caption:  θ FWHM measurements using 3C286 drift-scan observation. The circle markers show the mean of the best-fit θ FWHM across the measurements of different days and the filled region indicates the corresponding rms. The results of different beam models are shown in different colors. The black squares show the measurements from Jiang et al. (2020).
Paper: FAST Drift Scan Survey for HI Intensity Mapping: I. Preliminary Data Analysis
Authors: Yichao Li, Yougang Wang, Furen Deng, Wenxiu Yang, Wenkai Hu, Diyang Liu, Xinyang Zhao, Shifan Zuo, Shuanghao Shu, Jixia Li, Peter Timbie, Réza Ansari, Olivier Perdereau, Albert Stebbins, Laura Wolz, Fengquan Wu, Xin Zhang, Xuelei Chen
Figure caption: The smoothed bandpass of the XX (left-hand panels) and YY (right-hand panels) polarizations for the 20210302 data, i.e., those taken on 2021 March 2. The raw frequency resolution is 7.6 kHz. Top panels: The block-averaged bandpass, each block is shown in a different color, and the black curve shows the averaged bandpass across all blocks. Bottom panels: The bandpass relative variation with respect to the first block. The gray areas mark the frequency channels with over 20% time stamps flagged for RFI.
Paper: FAST Drift Scan Survey for HI Intensity Mapping: I. Preliminary Data Analysis
Authors: Yichao Li, Yougang Wang, Furen Deng, Wenxiu Yang, Wenkai Hu, Diyang Liu, Xinyang Zhao, Shifan Zuo, Shuanghao Shu, Jixia Li, Peter Timbie, Réza Ansari, Olivier Perdereau, Albert Stebbins, Laura Wolz, Fengquan Wu, Xin Zhang, Xuelei Chen
Figure caption: TOD analysis pipeline. The blue rectangles indicate the input/output data and the green rectangles indicate the operations performed on the data.  The data preparation is described at the beginning of Section 3. The calibration pipeline includes bandpass calibration (Section 3.1), temporal drift calibration (Section 3.2), and flux calibration (Section 3.3). The main pipeline, the RFI flagging, baseline subtraction, and the mapmaking are described in Section 3.5, Section 3.4, and Section 3.6, respectively.
Paper: FAST Drift Scan Survey for HI Intensity Mapping: I. Preliminary Data Analysis
Authors: Yichao Li, Yougang Wang, Furen Deng, Wenxiu Yang, Wenkai Hu, Diyang Liu, Xinyang Zhao, Shifan Zuo, Shuanghao Shu, Jixia Li, Peter Timbie, Réza Ansari, Olivier Perdereau, Albert Stebbins, Laura Wolz, Fengquan Wu, Xin Zhang, Xuelei Chen
Figure caption: The footprint of the FAST HI IM Pilot Survey observation using Zenith equal area projection (ZEA). The filled blue region shows the sky area of the major data observed in 2021, the green stripe indicates the test observation carried out on 2019 May 31st and 2020 May 8th, and the orange region shows the full target area for FAST HI IM Pilot Survey.
Paper: FAST Drift Scan Survey for HI Intensity Mapping: I. Preliminary Data Analysis
Authors: Yichao Li, Yougang Wang, Furen Deng, Wenxiu Yang, Wenkai Hu, Diyang Liu, Xinyang Zhao, Shifan Zuo, Shuanghao Shu, Jixia Li, Peter Timbie, Réza Ansari, Olivier Perdereau, Albert Stebbins, Laura Wolz, Fengquan Wu, Xin Zhang, Xuelei Chen
Figure caption: The footprint of the calibration observation. The red-dashed line represents 3C286's drift route as it crosses the meridian in the local alt-az coordinate at FAST site. The calibrator drifts through each line of feeds with five different pointing directions. The circles packed in hexagons illustrate the position of the 19 feeds in each pointing direction.
Paper: FAST Drift Scan Survey for HI Intensity Mapping: I. Preliminary Data Analysis
Authors: Yichao Li, Yougang Wang, Furen Deng, Wenxiu Yang, Wenkai Hu, Diyang Liu, Xinyang Zhao, Shifan Zuo, Shuanghao Shu, Jixia Li, Peter Timbie, Réza Ansari, Olivier Perdereau, Albert Stebbins, Laura Wolz, Fengquan Wu, Xin Zhang, Xuelei Chen
Figure caption: The best-fit η for different measurements.
Paper: FAST Drift Scan Survey for HI Intensity Mapping: I. Preliminary Data Analysis
Authors: Yichao Li, Yougang Wang, Furen Deng, Wenxiu Yang, Wenkai Hu, Diyang Liu, Xinyang Zhao, Shifan Zuo, Shuanghao Shu, Jixia Li, Peter Timbie, Réza Ansari, Olivier Perdereau, Albert Stebbins, Laura Wolz, Fengquan Wu, Xin Zhang, Xuelei Chen
Figure caption: The relative variation of the bandpass between different nights with respect to the first night’s observation (20210302).
Paper: ALMA 0.5 kpc Resolution Spatially Resolved Investigations of Nuclear Dense Molecular Gas Properties in Nearby Ultraluminous Infrared Galaxies Based on HCN and HCO+ Three Transition Line Data
Authors: Masatoshi Imanishi, 昌俊 今西, Shunsuke Baba, 俊介 馬場, Kouichiro Nakanishi, 康一郎 中西, Takuma Izumi, 拓磨 泉
Figure caption: 0.5 kpc beam-sized spectrum that includes the HC3N J = 18–17 or J = 21–20 line taken during the J21 observation. The abscissa is the observed frequency in GHz, and the ordinate is flux density in mJy. The HC3N J = 18–17 line (ν rest  = 163.753 GHz) is covered in all ULIRGs, except IRAS 22491−1808, for which the HC3N J = 21–20 line (ν rest  = 191.040 GHz) is included. A downward arrow is shown for the HC3N lines at the expected observed frequency of the adopted redshift (Table 1, column (2)). The question mark is added when a detection is unclear. The horizontal thin dotted straight line indicates the zero-flux level.
Paper: ALMA 0.5 kpc Resolution Spatially Resolved Investigations of Nuclear Dense Molecular Gas Properties in Nearby Ultraluminous Infrared Galaxies Based on HCN and HCO+ Three Transition Line Data
Authors: Masatoshi Imanishi, 昌俊 今西, Shunsuke Baba, 俊介 馬場, Kouichiro Nakanishi, 康一郎 中西, Takuma Izumi, 拓磨 泉
Figure caption: Integrated-intensity (moment 0) map of the HC3N J = 18–17 (for all ULIRGs but IRAS 22491−1808) or J = 21–20 line (for IRAS 22491−1808) created from the original beam-sized data (Table 3, column (2)). Only ULIRGs with a significant HC3N line detection are shown. Simultaneously obtained continuum emission (J21) is displayed as contours. The contours start from 4σ and increase by a factor of 2 (i.e., 8σ, 16σ, 32σ, and 64σ) for all sources. The continuum peak position is shown as a cross. The length of the vertical solid black bar for each object corresponds to 1 kpc. The beam size for each moment 0 map is shown as a filled white circle in the lower left region.
Paper: ALMA 0.5 kpc Resolution Spatially Resolved Investigations of Nuclear Dense Molecular Gas Properties in Nearby Ultraluminous Infrared Galaxies Based on HCN and HCO+ Three Transition Line Data
Authors: Masatoshi Imanishi, 昌俊 今西, Shunsuke Baba, 俊介 馬場, Kouichiro Nakanishi, 康一郎 中西, Takuma Izumi, 拓磨 泉
Figure caption: Integrated-intensity (moment 0) map of the CS J = 7–6 line created from the original beam-sized data (Table 3, column (4)). Continuum emission that was simultaneously obtained (J43) is shown as contours. The contours start from 4σ and increase by a factor of 2 (i.e., 8σ, 16σ, 32σ, and 64σ) for all ULIRGs. The continuum peak position is shown as a cross. The length of the vertical solid black bar at the right side of each object corresponds to 1 kpc. The beam size for each moment 0 map is shown as a filled white circle in the lower left region.
Paper: ALMA 0.5 kpc Resolution Spatially Resolved Investigations of Nuclear Dense Molecular Gas Properties in Nearby Ultraluminous Infrared Galaxies Based on HCN and HCO+ Three Transition Line Data
Authors: Masatoshi Imanishi, 昌俊 今西, Shunsuke Baba, 俊介 馬場, Kouichiro Nakanishi, 康一郎 中西, Takuma Izumi, 拓磨 泉
Figure caption: 0.5 kpc beam-sized spectrum that includes the CS J = 7–6 line, taken during the J43 observation. The abscissa is the observed frequency in GHz, and the ordinate is the flux density in mJy. An upward arrow is placed at the expected observed frequency of CS J = 7–6 for the adopted redshift (Table 1, column (2)). The horizontal thin dotted straight line indicates the zero-flux level.
Paper: ALMA 0.5 kpc Resolution Spatially Resolved Investigations of Nuclear Dense Molecular Gas Properties in Nearby Ultraluminous Infrared Galaxies Based on HCN and HCO+ Three Transition Line Data
Authors: Masatoshi Imanishi, 昌俊 今西, Shunsuke Baba, 俊介 馬場, Kouichiro Nakanishi, 康一郎 中西, Takuma Izumi, 拓磨 泉
Figure caption: Adopted Gaussian fit (solid curved line) of the CS J = 7–6 emission line in the 0.5 kpc beam-sized spectra for sources with a significant detection (all ULIRGs except IRAS 03250+1606). The abscissa is the optical LSR velocity in km s−1, and the ordinate is the flux density in mJy. The horizontal thin dotted straight line indicates the zero-flux level.
Paper: ALMA 0.5 kpc Resolution Spatially Resolved Investigations of Nuclear Dense Molecular Gas Properties in Nearby Ultraluminous Infrared Galaxies Based on HCN and HCO+ Three Transition Line Data
Authors: Masatoshi Imanishi, 昌俊 今西, Shunsuke Baba, 俊介 馬場, Kouichiro Nakanishi, 康一郎 中西, Takuma Izumi, 拓磨 泉
Figure caption:                         Same as Figure 18, but for the J = 3–2 lines of HCN and HCO+. No Gaussian fit is applied when there is no emission line signature at all, particularly in spectra of the 1–2 kpc annular region.
Paper: ALMA 0.5 kpc Resolution Spatially Resolved Investigations of Nuclear Dense Molecular Gas Properties in Nearby Ultraluminous Infrared Galaxies Based on HCN and HCO+ Three Transition Line Data
Authors: Masatoshi Imanishi, 昌俊 今西, Shunsuke Baba, 俊介 馬場, Kouichiro Nakanishi, 康一郎 中西, Takuma Izumi, 拓磨 泉
Figure caption:                         Same as Figure 18, but for the J = 4–3 lines of HCN and HCO+. No Gaussian fit is applied when there is no emission line signature at all, particularly in spectra of the 1–2 kpc annular region.
Paper: Physics-driven Machine Learning for the Prediction of Coronal Mass Ejections’ Travel Times
Authors: Sabrina Guastavino, Valentina Candiani, Alessandro Bemporad, Francesco Marchetti, Federico Benvenuto, Anna Maria Massone, Salvatore Mancuso, Roberto Susino, Daniele Telloni, Silvano Fineschi, Michele, Piana
Figure caption: Predicted transit time vs. actual transit time for CMEs in the test set in which the method reached the best performance. First row: results for configurations C1 and C4. Second row: results for configurations C2 and C5. Third row: results for configurations C3 and C6.
Paper: Fizzy Super-Earths: Impacts of Magma Composition on the Bulk Density and Structure of Lava Worlds
Authors: Kiersten M. Boley, Wendy R. Panero, Cayman T. Unterborn, Joseph G. Schulze, Romy Rodríguez Martínez, Ji Wang, 吉 王
Figure caption: (top) The depth of the solid–melt transition as a function of surface temperature for a 4 M ⊕ planet over a range of surface temperatures. The pressure on the y-axis corresponds to the hydrous melt (Model (4)). The core–mantle boundary pressures for all three scenarios are between 573 and 594 GPa. (bottom) We show the bulk planet density for each model as a function of surface temperature. The increase and decrease for Models (2) and (3) reflect the competing effects of thermal expansion and compression for a planet with a MOSMO structure. Additionally, we include Model (1), demonstrating the effects of thermal expansion on solid rock.
Paper: Fizzy Super-Earths: Impacts of Magma Composition on the Bulk Density and Structure of Lava Worlds
Authors: Kiersten M. Boley, Wendy R. Panero, Cayman T. Unterborn, Joseph G. Schulze, Romy Rodríguez Martínez, Ji Wang, 吉 王
Figure caption: Phase diagram for each model, showing the mantle structure for a given mass and surface temperature. We include likely lava worlds selected using criteria described in Section 3. The planets are colored by their bulk density ratio, which is their observed density divided by the expected density assuming an Earth-like composition. Planets distinguished with white circles and planet names are discussed in detail in Sections 4.2 and 4.3.
Paper: Fizzy Super-Earths: Impacts of Magma Composition on the Bulk Density and Structure of Lava Worlds
Authors: Kiersten M. Boley, Wendy R. Panero, Cayman T. Unterborn, Joseph G. Schulze, Romy Rodríguez Martínez, Ji Wang, 吉 王
Figure caption: We show an example of the four model scenarios using the results of our study of 4 M ⊕ planet with a surface temperature of 2000 K. Model (1) is a solid rocky planet, where liquid rock phases are neglected. For Model (2), we introduce a molten phase within the mantle in addition to the mantle. Model (3) has additional volatile CO2, making it a carbonated melt. Model (4), the hydrous melt, generally exhibits the largest increase in radius of the four scenarios.
Paper: Fizzy Super-Earths: Impacts of Magma Composition on the Bulk Density and Structure of Lava Worlds
Authors: Kiersten M. Boley, Wendy R. Panero, Cayman T. Unterborn, Joseph G. Schulze, Romy Rodríguez Martínez, Ji Wang, 吉 王
Figure caption: Solidus melt curves for the three magma compositions: Anhydrous (purple), Hydrous (teal), Carbonated (magenta). We include the pressure–temperature profile of a planet at a surface temperature, T surf = 2000 K and 1 Earth mass (orange). These are compared to the melt curves within the work of Dorn & Lichtenberg (2021), who use a piecewise solidus melt curve (green).
Paper: Fizzy Super-Earths: Impacts of Magma Composition on the Bulk Density and Structure of Lava Worlds
Authors: Kiersten M. Boley, Wendy R. Panero, Cayman T. Unterborn, Joseph G. Schulze, Romy Rodríguez Martínez, Ji Wang, 吉 王
Figure caption: Mantles structures produced by our model. We find that the mantle may be mantle magma ocean, a surface magma ocean and solid rock layer, or a MOSMO structure (i.e., Surface Magma Ocean (MO)–Solid Rock Layer (S)–Basal Magma Ocean (MO)).
Paper: Shadow Geometry of Kerr Naked Singularities
Authors: Bao Nguyen, Pierre Christian, Chi-kwan Chan
Figure caption: The topological features of KNS shadows for different spins 1 ≤ a ≤ 2.5 and observational inclination angles 0° ≤ i ≤ 90°. Regions A, B, and C denote that the shadow is closed, open, or vanishing, respectively. A shadow can only be closed for a ≲ 1.18. The maximum i for a closed shadow (yellow curve) asymptotically approaches 90° as a decreases toward 1. For a ≳ 1.18, a shadow cannot be closed and can vanish for certain ranges of i. As a increases from 1.18, the minimum i for the shadow to exist (blue curve) increases.
Paper: Shadow Geometry of Kerr Naked Singularities
Authors: Bao Nguyen, Pierre Christian, Chi-kwan Chan
Figure caption: Shadows of KNSs with different spins a and observational inclination angles i. From left to right, the plots correspond to a = 1.01, 1.06, and 1.18, respectively. In each plot, the shadow shifts from left to right and ranges from i = 15° to i = 75°, with increments of 15°. The colors represent the effective angular momentum Φ of each spherical photon orbit projected on the image plane and range from Φ = − 8 (retrograde) to Φ = 2 (prograde). Redder and bluer colors represent higher and lower effective angular momentum, respectively. The plots show that for a fixed spin 1 < a ≲ 1.18, the shadows can still be closed for lower inclinations due to the existence of prograde spherical photon orbits. As the inclination increases, the prograde photon orbits become more prograde. At some higher inclination angle, their effective angular momentum exceeds ﹩{{\rm{\Phi }}}_{\max }﹩, so they can no longer sustain spherical orbits, and the shadow opens up a gap. At a ≈ 1.18, all prograde spherical photon orbits no longer exist, so the shadow is always open for all inclinations.
Paper: Shadow Geometry of Kerr Naked Singularities
Authors: Bao Nguyen, Pierre Christian, Chi-kwan Chan
Figure caption: The unstable photon orbit radius r p (root(s) of β(r p) = 0) translated downward by the marginally stable radius r ms for different discrete spins a = 1.01, 1.05, 1.18, and 1.38 and continuous observational inclination angles −30° ≲ i < 90°. The solid lines represent unstable root of β(r p) = 0. The plot uses axial symmetry −i → i to illustrate the second unstable root, denoted in dotted lines, for certain values of a and i. The physical implication of the unstable root(s) in the KNS shadow is demonstrated in Figure 2.