Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · 2607.12950

Structure and Dynamics of the Inner Corona Measured from the DEB Initiative 2024 Eclipse Image Sequence

Matthew J Penn·Robert Baer·Chris Mandrell·Corinne Brevik·Castor Fu·Mike Conley·Richard Danley·Harvey Henson·David Iadevaia·Jonathan Mangin·Chris Midden·Brodye Miller·Claude Plymate·Teresa Plymate·Zack Stockbridge·Kevin Rasso·Autumn Awalt·Avery Awalt·Gracie Awalt·Josh Awalt·Lauree Rasso·Mike Chartrand·Noah Lambert·Zoee Rasso·Kevin Cobble·Amelia Menezes·Andrew Yu·Felix Mei·Hanson Du·Ramesh Pattar·Vishrut Kumaran·Robert Auburger·Brian J. Drake·Seth Antozzi·Chloe Rectanus·Grayson Garner·Michael Weiss·Bill Kloepping·Deborah Grubis·Maryanne Angliongto·Ashvik Chilakala·Carl Buz McCullough·Mark Bremer·Christina Adair·Amber Huffman·Charon Adair·Gabbie Graham·Nick Tillerson·Fred Isberner·Candy Isberner·Harry Treece·Lisa Sikorski·Sage Julian-Fralish·Heidi Schran·Addison Greene·Bibodh Baral·Crow Ely·Nolan Hodgson·Olive Blackmar Rice·Olivia Andrews·Olivia Freeman·Quinn Donnelly·Serenity Prince Kirk·Carmen Tran·Brianna Blanchard·Kyan West·Landon Bevier·Murali Saravanan·Jeremy Wright
View original source ↗Read source document ↗Export metadata ↓

Abstract

The Dynamic Eclipse Broadcast (DEB) Initiative citizen science program observed coronal visible continuum brightness during the 2024 April 8 total eclipse from locations across North America. We present results from 11 DEB sites spanning 2700 km of distance and showing 49 minutes of evolution. The coronal brightness radial profiles from these telescopes are tightly correlated from 1.2 to 4.0 solar radii and comparable to published photometric coronal intensities. The coronal flattening parameter is measured from 1.4 to 2.8 solar radii. A Ludendorff index of 0.0761 +/- 0.0007 is computed but the extrapolation techniques used by some to calculate this index are shown to disagree with this direct measurement, and alternate structure parameters are suggested. Measured radial velocities are compared with an MHD model of the corona during the eclipse from Y. Li et al. (2026). A polar downflow is measured with an average radial velocity of -37 +/- 3 km s-1 and a deceleration of 14 +/- 3 m s-2 at a speed and position which agrees with the model. The predicted mixture of outflows and downflows at low heights is seen, as well as outflows in two western regions of the corona. The fastest observed outflow has a radial speed of 105 km s-1 and is likely associated with a transient event not predicted by the model. Future DEB Initiative eclipse experiments can more tightly constrain models of the inner corona by using both coronal intensity and radial velocity measurements.

Explore related subjects

astro-ph.SR

Keep this discovery

BibTeXRIS

Matthew J Penn, Robert Baer, Chris Mandrell, Corinne Brevik, Castor Fu, Mike Conley, Richard Danley, Harvey Henson, David Iadevaia, Jonathan Mangin, Chris Midden, Brodye Miller, Claude Plymate, Teresa Plymate, Zack Stockbridge, Kevin Rasso, Autumn Awalt, Avery Awalt, Gracie Awalt, Josh Awalt, Lauree Rasso, Mike Chartrand, Noah Lambert, Zoee Rasso, Kevin Cobble, Amelia Menezes, Andrew Yu, Felix Mei, Hanson Du, Ramesh Pattar, Vishrut Kumaran, Robert Auburger, Brian J. Drake, Seth Antozzi, Chloe Rectanus, Grayson Garner, Michael Weiss, Bill Kloepping, Deborah Grubis, Maryanne Angliongto, Ashvik Chilakala, Carl Buz McCullough, Mark Bremer, Christina Adair, Amber Huffman, Charon Adair, Gabbie Graham, Nick Tillerson, Fred Isberner, Candy Isberner, Harry Treece, Lisa Sikorski, Sage Julian-Fralish, Heidi Schran, Addison Greene, Bibodh Baral, Crow Ely, Nolan Hodgson, Olive Blackmar Rice, Olivia Andrews, Olivia Freeman, Quinn Donnelly, Serenity Prince Kirk, Carmen Tran, Brianna Blanchard, Kyan West, Landon Bevier, Murali Saravanan, Jeremy Wright. 2026-07-14. Structure and Dynamics of the Inner Corona Measured from the DEB Initiative 2024 Eclipse Image Sequence. https://doi.org/10.3847/2041-8213/ae8797

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Eclipse Properties and Superhump Evolution in the SU UMa-Type Dwarf Nova Z Cha

The advent of large-scale time-domain surveys provides both opportunities and challenges for understanding accretion disk evolution in cataclysmic variables (CVs). Using high-cadence photometry from the Transiting Exoplanet Survey Satellite (TESS), we investigate the eclipsing SU UMa-type dwarf nova Z Cha. Leveraging eclipses as a natural probe, we examine the evolution of the accretion disk through variations in eclipse depth, O--C of eclipse minima, and positive superhump (PSH) amplitude. During superoutbursts, all three quantities exhibit quasi-periodic modulations with a common period of $\sim$2 days, consistent with the precession period of an eccentric disk. We interpret these correlated variations as evidence of an eccentric, precessing disk: O--C traces the periodic shift of the system's brightness center, while eclipse depth and PSH amplitude vary with the orientation of the disk bulge relative to the line of sight. In quiescence (Sectors 13 and 93), PSHs with periods of $\sim$0.0762 days show linearly decreasing amplitudes and periods, indicating gradual shrinkage of the eccentric disk and a slowing precession. Remarkably, a coherent signal with a period of $\sim$0.0729~days ($\epsilon^{-}\approx-0.02$) appears in the same quiescent intervals. This signal may represent negative superhumps (NSHs) coexisting with PSHs, although an orbital sideband of the PSH cannot presently be excluded with the available data. If confirmed as NSHs, their coexistence with PSHs would challenge the classical tilted-disk model, and could be explained by retrograde apsidal precession of an eccentric disk, where the inner disk precesses retrogradely (NSHs) and the outer disk progradely (PSHs); this interpretation remains to be tested by further observations.

astro-ph.SR↗
arXiv2026

Classical Nova V1405 Cas Had $M_{\rm ejecta}$$>$$M_{\rm accreted}$ and so is Unlikely to be a Type Ia Supernova Progenitor

Nova 2021 Cassiopeia (V1405 Cas) was an ordinary J(175) neon nova with the white dwarf mass estimated to be $M_{\rm WD}$=0.60$\pm$0.10 $M_{\odot}$. I found an orbital period of $P$=0.1884 days, and have tracked 20 times of photometric minima from 2013--2025. I measure that $P$ increased from before to after the eruption with $P_{\rm pre}$=0.1883919$\pm$0.0000018 days and $P_{\rm post}$=0.1884043$\pm$0.0000018 days, for $\Delta P$/$P$=66$_{-18}^{+21}$ parts-per-million. With correction for the angular momentum loss by the binary during the eruption, I derive that the nova ejected $M_{\rm ejecta}$=7.5$\times$10$^{-4}$ $M_{\odot}$, with an extreme range of (2.9--40)$\times$10$^{-4}$ $M_{\odot}$. The mass accreted during the previous eruption cycle comes from the trigger mass, and is $M_{\rm accreted}$=(1.6$\pm$0.4)$\times$10$^{-4}$ $M_{\odot}$. V1405 Cas provides counterexamples against five claims about CV evolution that have dominated since the 1980s. First, V1405 Cas has positive $\dot{P}$, and this is contrary to the Magnetic Braking Model. Second, the $\Delta P$ is 20$\times$ too small to allow the system to fade into a hibernation state. Third, $M_{\rm WD}$ is decreasing over time, as shown by $M_{\rm ejecta}$$>$$M_{\rm accreted}$ and by being a neon nova. Fourth, V1405 Cas is not a Type Ia supernova progenitor, for the same reasons. Fifth, the orbital period of V1405 Cas increased by $+$75 ppm from 2013--2025, as a counterexample to the pervasive idea that cataclysmic variables are universally declining in period from evolution. V1405 Cas is the latest of recent measures of $\Delta P$ and $\dot{P}$ for 52 cataclysmic variables and 25 X-ray binaries that have together refuted all five claims.

astro-ph.SR↗
arXiv2026

A prolonged plateau-to-tail transition in the Type II supernova SN2025abyc

We present optical photometric and spectroscopic observations of the Type II supernova SN2025abyc. During the optically thick phase between approximately 10 and 70 d after explosion, its light curves show strongly wavelength-dependent decline rates of approximately 2.7, 2.1, 0.9, and 0.8 mag/100d in the g, c, r, and o bands, respectively. At approximately 70 d, the light curves begin to depart from their nearly linear plateau evolution and gradually transition toward the radioactive tail. A Fermi-Dirac fit to the well-sampled ATLAS o-band light curve yields a transition midpoint of t_PT ~ 100.5d. The interval between the end of the linear plateau and this transition midpoint is approximately 30 d, indicating a prolonged plateau-to-tail transition. This timescale is comparable to those measured for SN2013by, SN2013ej, and SN2014G. Spectroscopically, at +13 d post-explosion, the Halpha profile appears weak and broad, whereas Hbeta and Hgamma display clear P-Cygni profiles. This morphology can be explained by the normal early spectroscopic evolution of SNe II, although partial filling of the Halpha absorption trough by emission associated with circumstellar interaction cannot be excluded. SN2025abyc otherwise follows the general photospheric velocity evolution of SNe II, while remaining toward the high-velocity side of the comparison distribution in Halpha, Hbeta, and FeII. Exploratory light-curve modelling suggests a synthesized Ni mass of approximately 0.03-0.04 solar mass. We suggest that the extended circumstellar environment, Ni distribution, and hydrogen-envelope structure could all play a role in shaping the observed light-curve evolution, particularly the prolonged plateau-to-tail transition.

astro-ph.SR↗