adsabs/AstroCLIMB huggingface dataset:
Paper: A Comprehensive Optical Search for Pre-explosion Outbursts from the Quiescent Progenitor of SN 2023ixf
Authors: Yize Dong, 一泽 董, David J. Sand, Stefano Valenti, K. Azalee Bostroem, Jennifer E. Andrews, Griffin Hosseinzadeh, Emily Hoang, Daryl Janzen, Jacob E. Jencson, Michael Lundquist, Nicolas E. Meza Retamal, Jeniveve Pearson, Manisha Shrestha, Joshua Haislip, Vladimir Kouprianov, Daniel E. Reichart
Figure caption: ZTF science and difference images at the position of SN 2023ixf before the explosion. The images are downloaded from the ZTF Science Data System (Masci et al. 2019; IRSA 2022) for illustrative purposes. The magenta circle marks the position of the SN. The 12 orange circles show a grid of sample positions around the SN. We performed forced photometry on these sample positions in addition to the SN location to check the reliability of the detections.
Paper: On the Theory of Ring Afterglows
Authors: Marcus DuPont, Andrew MacFadyen, Re'em Sari
Figure caption: Pictorial light curves for the spherical, ring-like, and jet-like blast waves, respectively. The left and right panels show the typical light-curve behavior at low (∼radio) and high (∼optical and X-ray) observed frequencies, respectively. The slopes are segmented in time between the break time, t  b , and the times when the break frequencies ν  m  and ν  c  cross the observed frequency ν. The vertical dashed line for t  c  is broken at the jet curve in the left panel since ν  c  is constant for that geometry and it therefore has no corresponding t  c . In both frequency bands, we show the divergence in flux decay rate once the break time is reached, with the low-frequency band showing the clearest separation between the various phases of evolution.
Paper: A Gigantic Mid-infrared Outburst in an Embedded Class I Young Stellar Object J064722.95+031644.6
Authors: Tinggui Wang, Jiaxun Li, Gregory N. Mace, Tuo Ji, Ning Jiang, Qingfeng Zhu, Min Fang
Figure caption: In the upper panel, WISE survey MIR light curves for J064722.95+031644.6 in the W1 and W2 bands. Photometry is obtained from the differential image in the unWISE image with reference to epoch 1, except for the last four epochs (see the text for details). The magnitudes in the IRAC 1 and IRAC2 bands at MJD = 56602 are used for constant fluxes. Vertical dashed lines indicate the dates of NIR spectroscopic observations. The bottom panel shows the flux ratios between the W1 and W2 bands over the period.
Paper: On the Theory of Ring Afterglows
Authors: Marcus DuPont, Andrew MacFadyen, Re'em Sari
Figure caption: Cartoon illustrations of the two types of asymmetric geometries considered in this article. The left shows the conical, jet-like outflow along the poles of the source, while the right shows the ring-like outflow in the equatorial plane of the source. Velocity arrows are drawn perpendicular to the bulk flow to show the spreading characteristics for each geometry. The half-opening angle, θ 0, is depicted for both geometries as well.
Paper: A Gigantic Mid-infrared Outburst in an Embedded Class I Young Stellar Object J064722.95+031644.6
Authors: Tinggui Wang, Jiaxun Li, Gregory N. Mace, Tuo Ji, Ning Jiang, Qingfeng Zhu, Min Fang
Figure caption: 30″ ×30″ difference images around J0647 with the corresponding epoch 1 image as the reference in the W1 band. J0647 and the bright star are marked with o1 and s1, respectively. The young star (Y1), which is also variable, is located in the upper left corner.
Paper: The Inhomogeneity Effect. I. Inhomogeneous Surface and Atmosphere Accelerate Planetary Cooling
Authors: Xi Zhang
Figure caption: Concave response functions of surface temperature in relation to the incident stellar flux and opacity on terrestrial planets, with the diffusivity parameter D set to 2. In panels (A) and (B), the solid lines represent the visible-to-IR opacity ratio α = 0.5 and the adiabatic slope parameter β ∼ 0.38. The dashed lines, on the other hand, correspond to α = 0.05 and β ∼ 0.76. Panel (A) illustrates how the surface temperature changes with the incident stellar flux when the opacity is kept constant, corresponding to a surface IR optical depth of τ s = 3. Panel (B) demonstrates the variation in surface temperature as the IR opacity coefficient κ increases, with the surface IR optical depth τ s changing from 3 to 100. In this panel, the incident stellar flux (F ⊙ = 1) is held constant, and we also kept α fixed, ensuring that the visible and IR opacity increase by the same factor. Panel (C) exhibits the alteration in the surface temperature as the visible-to-IR opacity ratio increases. In this case, we maintain the incident stellar flux (F ⊙ = 1) and κ (corresponding to τ s = 10) as fixed. Here, only one scenario (β ∼ 0.38) of varying α is displayed because the maximum α (approximately 0.0665) in the other case is too small to be plotted on the same graph. Panel (D) mirrors panel (B), with fixed F ⊙ = 1 and varying IR opacity coefficient κ. However, in this panel, we also vary α so that the visible opacity (α τ) remains unaffected by the IR opacity (τ). We ensure the product α κ is constant, implying α τ s = 3 for the β ∼ 0.38 case (solid) and α τ s = 0.3 for the β ∼ 0.76 case (dashed line).
Paper: The Inhomogeneity Effect. I. Inhomogeneous Surface and Atmosphere Accelerate Planetary Cooling
Authors: Xi Zhang
Figure caption: Response functions of outgoing internal heat flux F int to incident stellar flux and opacity on giant planets. We selected the diffusivity parameter D = 2 and the adiabatic slope parameter β ∼ 0.76. Two irradiated planet cases are displayed with the visible-to-IR opacity ratio α = 0.5 (solid) and α = 5 (dashed). An additional self-illuminated planet case is shown in panel (B). Panel (A) represents the variation of the internal heat flux with the incident stellar flux F ⊙. Here, the opacity is kept constant with a fixed K = 0.2 (refer to Equation (32) for the definition of K). Panel (B) demonstrates the variation of the internal heat flux with the IR opacity coefficient κ, with the incident stellar flux held constant at F ⊙ = 1. As α is fixed, the visible opacity varies by the same factor for irradiated planets (solid and dashed lines). To retain the same interior temperature at the same pressure, K is scaled with κ via K ∝ κ −β  for all planets. Panel (C) presents the change in the surface temperature as the visible-to-IR opacity ratio escalates, with fixed incident stellar flux (F ⊙ = 1) and K = 0.2. Panel (D) mirrors panel (B), with a fixed F ⊙ = 1 and varying IR opacity coefficient κ (and K accordingly), but here α is also varied such that the visible opacity (α τ) does not alter with the IR opacity (τ). The product α κ is held constant for both cases. The response functions are convex in panels (A), (B), and (D) and concave in panel (C).
Paper: The Inhomogeneity Effect. I. Inhomogeneous Surface and Atmosphere Accelerate Planetary Cooling
Authors: Xi Zhang
Figure caption: Mixing of two inhomogeneous RCE columns for terrestrial cases, with the diffusivity parameter D set at 2. Similar to Figure 2, the solid lines correspond to the visible-to-IR opacity ratio α = 0.5 and the adiabatic slope parameter β ∼ 0.38, while the dashed lines represent α = 0.05 and β ∼ 0.76. The left panels show scenarios with inhomogeneous incident stellar flux, with the IR opacity coefficient κ maintained constant, corresponding to the surface IR optical depth τ s = 3. The panels on the right present cases with inhomogeneous opacities, wherein the same scaling factor is applied to both visible and IR opacity while keeping the incident stellar flux constant at F ⊙ = 1. Panel (A) illustrates the temperature profiles as a function of normalized pressure (p/p s) for normalized incident stellar flux F ⊙ = 0.1 (blue), 1 (black, the mixed column), and 1.9 (red). Panel (B) shows the temperature profiles as a function of normalized pressure when scaling the IR opacity coefficient κ by a factor of 1 (blue), 5.5 (black, the mixed column), and 10 (red). This corresponds to the surface IR optical depth τ s of 3, 16.5, and 30, respectively. Panel (C) displays the ratios of the averaged surface temperature T s between the inhomogeneous columns and the homogeneous column as the contrast of incident stellar flux increases, with κ held constant. The solid and dashed curves overlap in this panel. Panel (D) presents the ratios of the averaged surface temperature T s between the inhomogeneous and the homogeneous columns as the opacity contrast amplifies, with a fixed incident stellar flux.
Paper: The Inhomogeneity Effect. I. Inhomogeneous Surface and Atmosphere Accelerate Planetary Cooling
Authors: Xi Zhang
Figure caption: Mixing of two inhomogeneous RCE columns for giant planet cases. The diffusivity parameter is chosen as D = 2, and the adiabatic slope parameter is β ∼ 0.76. Two cases of irradiated planets are presented with visible-to-IR opacity ratios α = 0.5 (solid line) and α = 5 (dashed line), alongside an additional case of a self-illuminated planet shown in panel (B). The left panels display cases with inhomogeneous incident stellar flux while maintaining constant opacity and K = 0.2. The right panels show cases with inhomogeneous opacities for irradiated (solid and dashed lines) and self-luminous bodies (dotted line), with constant incident stellar flux set as F ⊙ = 1. Panel (A) Temperature profiles plotted as a function of normalized pressure (p/p s) for normalized incident stellar flux F ⊙ = 0.1 (blue), 1 (black, the mixed column), and 1.9 (red lines). Panel (B) Temperature profiles as a function of normalized pressure for IR opacity coefficient κ scaled by factors of 1 (blue lines), 5.5 (black lines, the mixed column), and 10 (red lines) with corresponding adjustments to K. Panels (C) and (D) present the ratios of the average F int in the inhomogeneous columns compared to the homogeneous column when varying the contrast of the incident stellar flux (with fixed opacity) and opacity (with fixed stellar flux), respectively. The dashed and dotted curves overlap in panel (C).
Paper: The Inhomogeneity Effect. I. Inhomogeneous Surface and Atmosphere Accelerate Planetary Cooling
Authors: Xi Zhang
Figure caption: The ratio of the averaged surface temperature T s in the inhomogeneous columns compared to the homogeneous column as a function of the incident stellar flux and opacity contrast between the two columns. We adopted the diffusivity parameter D = 2, visible-to-IR opacity ratio α = 0.5, and the adiabatic slope parameter β ∼ 0.38. The reference incident stellar flux is set at F ⊙ = 1, and the incident stellar flux of the second column varies from 0.05 to 20. The reference IR opacity coefficient κ is set so that the surface IR optical depth τ s is 20, and τ s in the second column varies from 1 to 400.
Paper: The Inhomogeneity Effect. I. Inhomogeneous Surface and Atmosphere Accelerate Planetary Cooling
Authors: Xi Zhang
Figure caption: The ratio of the averaged outgoing internal heat flux in the inhomogeneous columns compared to the homogeneous column as a function of the incident stellar flux and opacity contrast between the two columns. We have selected the diffusivity parameter D = 2, visible-to-IR opacity ratio α = 1, and the adiabatic slope parameter β ∼ 0.76. The reference incident stellar flux is set at F ⊙ = 1, and the reference IR opacity coefficient κ is 1, corresponding to K = 0.2. In the second column, both quantities were varied by a factor ranging from 0.05–20.
Paper: The Inhomogeneity Effect. I. Inhomogeneous Surface and Atmosphere Accelerate Planetary Cooling
Authors: Xi Zhang
Figure caption: Diffusivity factor as a function of optical depth from different theories: ﹩D=-\mathrm{log}(2{E}_{3}(x))/x﹩ (black line) in Armstrong (1968), D = E 1(x)/E 2(x) (red), and D = E 2(x)/E 3(x) (blue) in this work. Typical constant values of D are used in practice (gray dashed line).
Paper: Investigating the Magnetic Structure of Interplanetary Coronal Mass Ejections Using Simultaneous Multispacecraft In Situ Measurements
Authors: F. Regnault, N. Al-Haddad, N. Lugaz, C. J. Farrugia, W. Yu, E. E. Davies, A. B. Galvin, B. Zhuang
Figure caption: In situ measurements of the 2011 September 17 CME observed at Wind (green) and Juno (orange). The panels show, from top to bottom, the magnitude of the magnetic field and its components in RTN coordinates in nT, the density in cm−3, the proton β parameter (red), and the speed in kilometers per second.
Paper: Beyond the Drake Equation: A Time-dependent Inventory of Habitable Planets and Life-bearing Worlds in the Solar Neighborhood
Authors: Piero Madau
Figure caption: MDF of the GALAH+TGAS sample (red histogram; Buder et al. 2019). The distribution is skewed toward the metal-poor tail, with 59% of the stars having metallicities below solar. Note that, for plotting purposes, the histogram is expressed in densities and not in frequencies. The blue line shows a best-fit distribution in bins of M of the form ﹩G{(M)=a({10}^{M})}^{b}\,\exp (-c{10}^{M})﹩, where ﹩M\equiv {\mathrm{log}}_{10}Z/{Z}_{\odot }﹩, a = 128, b = 4.1, and c = 4.25. The mean metallicity, standard deviation, and skewness of the distribution are provided in the main text.
Paper: Beyond the Drake Equation: A Time-dependent Inventory of Habitable Planets and Life-bearing Worlds in the Solar Neighborhood
Authors: Piero Madau
Figure caption: The SFH of the solar neighborhood. The blue pentagons with error bars show the marginalized age distribution (the fraction of stars formed per unit time at age t 0 − t) inferred by Alzate et al. (2021; grid C, extinction corrected) for stars brighter than G = 15 mag in Gaia DR2. The solid curve displays a reasonable reconstruction of the local SFH involving four Gaussians centered at ages of 10, 5.5, 2.0, and 0.7 Gyr, having widths of 1.2, 0.9, 0.35, and 0.3 Gyr, respectively, and relative peaks 1:1.36:0.71:0.86. The dotted line indicates the three late peaks in the SFH (with a different normalization for illustration purposes) of the (kinematically defined) thin stellar disk derived by Ruiz-Lara et al. (2020).
Paper: Beyond the Drake Equation: A Time-dependent Inventory of Habitable Planets and Life-bearing Worlds in the Solar Neighborhood
Authors: Piero Madau
Figure caption: Stellar age–metallicity relation in the solar neighborhood. The solid curve shows the result of the integration of Equation (5) for the assumed SFH ψ(t) (Figure 2) and MDF g(Z) (Figure 3). The inferred relationship is in broad agreement with the mean abundance trends vs. age recovered by Snaith et al. (2015) for the inner (dashed curve) and outer (dotted–dashed curve) Milky Way disk. Note that stars in the solar vicinity have none of the characteristics of inner disk stars, and are better described as outer disk objects (Haywood et al. 2019).
Paper: Beyond the Drake Equation: A Time-dependent Inventory of Habitable Planets and Life-bearing Worlds in the Solar Neighborhood
Authors: Piero Madau
Figure caption: Main-sequence lifetimes t ms for stars with masses of 0.7, 0.8, 0.9, and 1.0 M ⊙ (from top to bottom) at different metallicities, ﹩-2.2\,\lt {\mathrm{log}}_{10}(Z/{Z}_{\odot })\lt 0.4﹩ (Hurley et al. 2000; “old” solar composition). The points show the results of the more recent stellar evolution calculations by Truitt et al. (2015; the “enhanced oxygen abundance” model).
Paper: Illuminating the Dark Side of Cosmic Star Formation. II. A Second Date with RS-NIRdark Galaxies in COSMOS
Authors: Meriem Behiri, Margherita Talia, Andrea Cimatti, Andrea Lapi, Marcella Massardi, Andrea Enia, Cristian Vignali, Matthieu Bethermin, Andreas Faisst, Fabrizio Gentile, Marika Giulietti, Carlotta Gruppioni, Francesca Pozzi, Vernesa Smolçić, Gianni Zamorani
Figure caption: Left: comparison between the photometric redshifts computed with and without the 350 and 500 μm photometric data. Right: distribution of the reduced χ 2 of the SED fitting for the sources in the A3COSMOS sample obtained using the whole photometry (crimson) and without the 350 and 500 μm.
Paper: Bridging between Type IIb and Ib Supernovae: SN IIb 2022crv with a Very Thin Hydrogen Envelope
Authors: Anjasha Gangopadhyay, Keiichi Maeda, Avinash Singh, Nayana A. J., Tatsuya Nakaoka, Koji S. Kawabata, Kenta Taguchi, Mridweeka Singh, Poonam Chandra, Stuart D. Ryder, Raya Dastidar, Masayuki Yamanaka, Miho Kawabata, Rami Z. E. Alsaberi, Naveen Dukiya, Rishabh Singh Teja, Bhavya Ailawadhi, Anirban Dutta, D. K. Sahu, Takashi J. Moriya, Kuntal Misra, Masaomi Tanaka, Roger Chevalier, Nozomu Tominaga, Kohki Uno, Ryo Imazawa, Taisei Hamada, Tomoya Hori, Keisuke Isogai
Figure caption: The relation between the pseudo-bolometric optical–NIR luminosity in the “shock-cooling phase” and the density of the CSM is shown in the first panel. Upper limits for the cooling luminosities are derived for the objects that lacked a primary peak, like SN 2008ax and SN 2022crv. The second panel shows the relation between the CSM density and the progenitor’s radius, and the third panel describes the relation between mass-loss rates and the progenitor’s radius. The typical CSM densities assumed for SNe Ib/c are indicated by the shaded region (Chevalier & Fransson 2006), though they may contain a systematic uncertainty of up to an order of magnitude (Maeda 2012).
Paper: Bridging between Type IIb and Ib Supernovae: SN IIb 2022crv with a Very Thin Hydrogen Envelope
Authors: Anjasha Gangopadhyay, Keiichi Maeda, Avinash Singh, Nayana A. J., Tatsuya Nakaoka, Koji S. Kawabata, Kenta Taguchi, Mridweeka Singh, Poonam Chandra, Stuart D. Ryder, Raya Dastidar, Masayuki Yamanaka, Miho Kawabata, Rami Z. E. Alsaberi, Naveen Dukiya, Rishabh Singh Teja, Bhavya Ailawadhi, Anirban Dutta, D. K. Sahu, Takashi J. Moriya, Kuntal Misra, Masaomi Tanaka, Roger Chevalier, Nozomu Tominaga, Kohki Uno, Ryo Imazawa, Taisei Hamada, Tomoya Hori, Keisuke Isogai
Figure caption: Corner plot showing the results of MCMC modeling of the SN 2022crv radio data with the SSA model. The parameters here are according to Equations (3) and (4), respectively.
Paper: Evidence for Large-scale, Rapid Gas Inflows in z ∼ 2 Star-forming Disks
Authors: R. Genzel, J.-B. Jolly, D. Liu, S. H. Price, L. L. Lee, N. M. Förster Schreiber, L. J. Tacconi, R. Herrera-Camus, C. Barfety, A. Burkert, Y. Cao, R. I. Davies, A. Dekel, M. M. Lee, D. Lutz, T. Naab, R. Neri, A. Nestor Shachar, S. Pastras, C. Pulsoni, A. Renzini, K. Schuster, T. T. Shimizu, F. Stanley, A. Sternberg, H. Übler
Figure caption: Cartoons of axisymmetric, in-plane outflows (left) and inflows (right) in a galaxy viewed at an inclination of 130° (top row; rotating clockwise) and 50° (bottom row, rotating counterclockwise), respectively. The PA of the major axis is PAmajor = 180° in all panels. The largest negative (approaching) and positive (receding) velocities thus occur near PA = 0° and 180°. In all cartoons, we also added trailing spiral arms. Labeled quadrants 1–4 are along the in-plane rotation direction from the approaching side. Then the characteristic of inflow (outflow) is that, for the inclination >90° case (top row), in quadrants 1 and 2 the projected radial velocity has the opposite (same) sign from the projected rotation velocity at PA = 0°, while in quadrants 3 and 4 the projected radial velocity has the same (opposite) sign of the projected rotation velocity at PA = 0°. If the inclination of the galaxy is less than 90° (bottom row), these relative signs stay the same but the rotation is now counterclockwise.
Paper: Evidence for Large-scale, Rapid Gas Inflows in z ∼ 2 Star-forming Disks
Authors: R. Genzel, J.-B. Jolly, D. Liu, S. H. Price, L. L. Lee, N. M. Förster Schreiber, L. J. Tacconi, R. Herrera-Camus, C. Barfety, A. Burkert, Y. Cao, R. I. Davies, A. Dekel, M. M. Lee, D. Lutz, T. Naab, R. Neri, A. Nestor Shachar, S. Pastras, C. Pulsoni, A. Renzini, K. Schuster, T. T. Shimizu, F. Stanley, A. Sternberg, H. Übler
Figure caption: Model velocity maps of a rotating disk galaxy with parameters like Q2343_BX610 (﹩{v}_{{\rm{c}}}\left({R}_{{\rm{e}}}=4\ \mathrm{kpc}\right)=295\ \mathrm{km}\ {{\rm{s}}}^{-1}﹩, i = 39°, PAmajor = −25°). Left: model velocity map without any radial motion. Top center and right: model velocity (center) and residual (v  c (no flow) − v  c (flow)) velocity map of a galaxy with 100 km s−1 axisymmetric inflow. Bottom center and right: same for a 100 km s−1 inflow along a bar at PAinflow = −156°, or δPA = PAinflow − PAmajor = −131° with respect to the kinematic major axis of rotation.
Paper: Investigating the Magnetic Structure of Interplanetary Coronal Mass Ejections Using Simultaneous Multispacecraft In Situ Measurements
Authors: F. Regnault, N. Al-Haddad, N. Lugaz, C. J. Farrugia, W. Yu, E. E. Davies, A. B. Galvin, B. Zhuang
Figure caption: In situ measurements of the 1997 December 10 CME observed at Wind (green) and NEAR (orange), presented in the same format as Figure 1.
Paper: Investigating the Magnetic Structure of Interplanetary Coronal Mass Ejections Using Simultaneous Multispacecraft In Situ Measurements
Authors: F. Regnault, N. Al-Haddad, N. Lugaz, C. J. Farrugia, W. Yu, E. E. Davies, A. B. Galvin, B. Zhuang
Figure caption: Panel (a) shows the instantaneous profile following the procedure of Démoulin et al. (2020) at Wind on 1997 December 10. Panel (b) shows the reconstructed profile for the Wind–NEAR event marked by a red line. Light green and orange lines correspond to the portions of the ME profile at Wind and NEAR that are not used to build the reconstructed profile. See Section 4.4 for more details.
Paper: Evidence for Large-scale, Rapid Gas Inflows in z ∼ 2 Star-forming Disks
Authors: R. Genzel, J.-B. Jolly, D. Liu, S. H. Price, L. L. Lee, N. M. Förster Schreiber, L. J. Tacconi, R. Herrera-Camus, C. Barfety, A. Burkert, Y. Cao, R. I. Davies, A. Dekel, M. M. Lee, D. Lutz, T. Naab, R. Neri, A. Nestor Shachar, S. Pastras, C. Pulsoni, A. Renzini, K. Schuster, T. T. Shimizu, F. Stanley, A. Sternberg, H. Übler
Figure caption: Angles in Equation (1). Left: the azimuthal angle θ within the galactic plane. Middle: the inclination angle i of the galaxy plane relative to the sky plane (face-on is i = 0 (counterclockwise) or 180° (clockwise)). Right: the position angle of a galactic position projected on the sky, ϕ (positive east of north), and the PA of the major axis of the galaxy projected on the sky, ϕ 0.
Paper: Investigating the Magnetic Structure of Interplanetary Coronal Mass Ejections Using Simultaneous Multispacecraft In Situ Measurements
Authors: F. Regnault, N. Al-Haddad, N. Lugaz, C. J. Farrugia, W. Yu, E. E. Davies, A. B. Galvin, B. Zhuang
Figure caption: Schematic showing the different possible configurations of the spacecraft during a simultaneous measurement of a low and highly inclined ME.
Paper: Investigating the Magnetic Structure of Interplanetary Coronal Mass Ejections Using Simultaneous Multispacecraft In Situ Measurements
Authors: F. Regnault, N. Al-Haddad, N. Lugaz, C. J. Farrugia, W. Yu, E. E. Davies, A. B. Galvin, B. Zhuang
Figure caption: Summary plot of the catalog of MEs measured simultaneously by two spacecraft. Panels (a) and (b) show the DiP and front-to-back ratio measured at both spacecraft, respectively, for all events (green and orange data points; bottom scale) and the absolute value of the difference between the two spacecraft (blue histograms; top scale).
Paper: Investigating the Magnetic Structure of Interplanetary Coronal Mass Ejections Using Simultaneous Multispacecraft In Situ Measurements
Authors: F. Regnault, N. Al-Haddad, N. Lugaz, C. J. Farrugia, W. Yu, E. E. Davies, A. B. Galvin, B. Zhuang
Figure caption: Mean magnetic field (in nT) of the ME as a function of the radial distance (in au; panel (a)) and angular separation (in degrees; panel (b)).