Pith. sign in

REVIEW 38 references

The Temperature-dependent Damping of Propagating Slow Magnetoacoustic Waves

T0 review · reviewed 2026-08-14 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗ Review JSON

Pith's one-line read First measurement of the temperature dependence of slow magnetoacoustic wave damping lengths in coronal fan loops finds no apparent decrease with temperature, conflicting with thermal conduction expectations.

arxiv 1908.00384 v1 pith:JD6G4JWW submitted 2019-08-01 astro-ph.SR

S. Krishna Prasad , D. B. Jess , T. Van Doorsselaere This is my paper · ORCID
classification astro-ph.SR
keywords dampingconductionthermalwavesmagnetoacousticslowbeendominant
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The Sun's corona is threaded with magnetic loops. Waves called slow magnetoacoustic waves travel along these loops and fade quickly. Scientists have thought that heat conduction, the flow of heat from hot to cool plasma, is the main thing that makes these waves fade. This paper tests that idea by measuring how quickly the waves fade in 35 coronal loops with different temperatures. The authors used movies from the SDO satellite in ultraviolet light. They traced the wave crests along each loop and measured the distance the wave travels before its brightness drops by a factor of e. They did this in two separate ways and got similar answers. They then plotted each loop's fading distance against its temperature. Standard thermal conduction theory predicted that hotter loops should fade over much shorter distances. Instead, the observed fading distance showed no clear tendency to shrink with temperature. The mismatch was large: the theoretical fading distances were hundreds of megameters, while the observed ones were only a few megameters. This suggests either that thermal conduction is much weaker in hotter loops than the standard formula says, or that something else, not thermal conduction, is doing most of the damping. The authors are careful to list caveats: the temperature of each loop is uncertain, the measured distances are projected on the sky and are lower limits, and the loops cover only a limited temperature range. The result is important because it challenges a long-standing assumption about how wave energy is removed from the corona, which matters for understanding how the corona is heated.
Extended reading notes

Core claim

The paper's central claim is that the measured damping length of propagating slow magnetoacoustic waves in coronal fan loops does not decrease with loop temperature, contrary to the expectation from thermal conduction damping; the authors infer that thermal conduction is suppressed in hotter loops or is not the dominant damping mechanism. Abstract: 'The results do not indicate any apparent decrease in damping length with temperature, which is in contrast to the existing viewpoint.'

Load-bearing premise

The comparison across loops assumes that the DEM peak temperature from a double-Gaussian fit to the regularized inversion is a faithful single temperature for each loop and is the correct input for the thermal conduction damping calculation. The authors note in Section 4 that 'it can be argued whether the peak emission in a DEM sufficiently represents the plasma within the loop.' If temperature biases vary systematically with loop properties, the observed absence of a damping-length trend could be an artifact.

Share X Bluesky LinkedIn Reddit HN

Signed reviews

No signed human review yet.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Assumptions & free parameters 0 free parameters · 5 assumptions · 0 invented entities

The paper introduces no new physical entities and no ad-hoc free parameters; all theoretical inputs (temperature, density, polytropic index, period) come from prior measurements on the same loops. The analysis assumes standard linear MHD wave theory with Spitzer thermal conduction and that the DEM peak temperature represents each loop's plasma.

assumptions (5)
  • domain assumption The observed compressive oscillations in fan loops are propagating slow magnetoacoustic waves.
    Section 3, based on prior identification of similar oscillations (Kiddie et al. 2012; Krishna Prasad et al. 2012b).
  • domain assumption The weak thermal conduction limit (dω << 1) applies to the analyzed loops.
    Section 3.3, authors report dω values in the range 0.01-0.16.
  • domain assumption Spitzer thermal conductivity with κ0 = 7.8e-7 is the correct conductivity.
    Section 3.3, used without modification.
  • domain assumption The temperature, density, polytropic index, and period values from Krishna Prasad et al. (2018) are accurate for these loops.
    Sections 2 and 3.3, used as inputs to theoretical damping lengths.
  • domain assumption The 1D linear wave theory with thermal conduction as the damping mechanism is applicable.
    Equation (3) and the damping length formula are from De Moortel and Hood (2003) and Mandal et al. (2016).

how reviews work

0 comments
Cite this review

Pith. "Pith review of The Temperature-dependent Damping of Propagating Slow Magnetoacoustic Waves." pith.science (2026). https://pith.science/paper/JD6G4JWW

@misc{pith2026190800384,
  author       = {Pith},
  title        = {Pith review of: The Temperature-dependent Damping of Propagating Slow Magnetoacoustic Waves},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/JD6G4JWW}},
  note         = {Machine review of arXiv:1908.00384}
}
read the original abstract

The rapid damping of slow magnetoacoustic waves in the solar corona has been extensively studied in previous years. Most studies suggest that thermal conduction is a dominant contributor to this damping, albeit with a few exceptions. Employing extreme-ultraviolet (EUV) imaging data from SDO/AIA, we measure the damping lengths of propagating slow magnetoacoustic waves observed in several fan-like loop structures using two independent methods. The dependence of the damping length on temperature has been studied for the first time. The results do not indicate any apparent decrease in damping length with temperature, which is in contrast to the existing viewpoint. Comparing with the corresponding theoretical values calculated from damping due to thermal conduction, it is inferred that thermal conduction is suppressed in hotter loops. An alternative interpretation that suggests thermal conduction is not the dominant damping mechanism, even for short period waves in warm active region loops, is also presented.

Figures

Figures reproduced from arXiv: 1908.00384 by the authors.

Figure 1
Figure 1. (a) A snapshot of the fan-like loop structures from NOAA AR 12553 captured in the SDO/AIA 171 A˚ channel. The blue solid lines mark the boundaries of a chosen loop segment. (b) Time-distance map depicting the evolution of the loop segment shown in (a). The alternating slanted bands of brightness apparent in this map indicate the presence of propagating compressive oscillations due to slow magnetoacoustic waves. (c) … view at source ↗
Figure 2
Figure 2. (a) Spatial variation of the relative intensity at the temporal location marked by the white dashed line in Fig. 1c. The vertical bars denote the respective uncertainties. The solid curve represents the best fit to the data for an exponentially decaying sine wave model following Eq. 1. The obtained damping length value from the fitted curve is listed in the upper-right corner of the plot. (b) Damping lengths extract… view at source ↗
Figure 3
Figure 3. (a) Relative amplitudes of the oscillations as a function of distance along the loop segment marked by the solid blue lines in Fig. 1a. The vertical bars denote the respective uncertainties. The black solid line represents an exponential fit to the decaying phase of the data following Eq. 2. The obtained damping length value from the fitted curve is listed in the plot. (b) Damping lengths extracted from all the sele… view at source ↗

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

38 extracted references · 13 canonical work pages

  1. [1]

    !1A Qa

    thebibliography [1] 20pt to REFERENCES 6pt =0pt 10pt plus 3pt =0pt =0pt =1pt plus 1pt =0pt =0pt -12pt =13pt plus 1pt =20pt =13pt plus 1pt \@M =10000 =-1.0em =0pt =0pt 0pt =0pt =1.0em @enumiv\@empty 10000 10000 `\.\@m \@noitemerr \@latex@warning Empty `thebibliography' environment \@ifnextchar \@reference \@latexerr Missing key on reference command Each re...

    1998

  2. [2]

    and Krishna Prasad , S

    Banerjee , D. and Krishna Prasad , S. (2016). MHD Waves in Coronal Holes . Washington DC American Geophysical Union Geophysical Monograph Series 216, 419--430. doi:10.1002/9781119055006.ch24 2016GMS...216..419B

    doi:10.1002/9781119055006.ch24 2016

  3. [3]

    and Clette , F

    Berghmans , D. and Clette , F. (1999). Active region EUV transient brightenings - First Results by EIT of SOHO JOP80 . 186, 207--229 bc1999SoPh186

    work page 1999

  4. [4]

    S., Bogdan , T

    Cally , P. S., Bogdan , T. J., and Zweibel , E. G. (1994). Umbral oscillations in sunspots: Absorption of p-modes and active region heating by mode conversion . 437, 505--521. doi:10.1086/175014 1994ApJ...437..505C

    doi:10.1086/175014 1994

  5. [5]

    L., Harra , L

    Culhane , J. L., Harra , L. K., James , A. M., Al-Janabi , K., Bradley , L. J., Chaudry , R. A., et al. (2007). The EUV Imaging Spectrometer for Hinode . 243, 19--61. doi:10.1007/s01007-007-0293-1 2007SoPh..243...19C

    doi:10.1007/s01007-007-0293-1 2007

  6. [6]

    De Moortel , I. (2009). Longitudinal Waves in Coronal Loops . 149, 65--81. doi:10.1007/s11214-009-9526-5 2009SSRv..149...65D

    doi:10.1007/s11214-009-9526-5 2009

  7. [7]

    and Hood , A

    De Moortel , I. and Hood , A. W. (2003). The damping of slow MHD waves in solar coronal magnetic fields . 408, 755--765. doi:10.1051/0004-6361:20030984 2003A&A...408..755D

    work page doi:10.1051/0004-6361:20030984 2003

  8. [8]

    and Hood , A

    De Moortel , I. and Hood , A. W. (2004). The damping of slow MHD waves in solar coronal magnetic fields. II. The effect of gravitational stratification and field line divergence . 415, 705--715. doi:10.1051/0004-6361:20034233 2004A&A...415..705D

    doi:10.1051/0004-6361:20034233 2004

Show all 38 references
  1. [9]

    De Moortel , I., Ireland , J., and Walsh , R. W. (2000). Observation of oscillations in coronal loops . 355, L23--L26 2000A&A...355L..23D

    2000

  2. [10]

    De Pontieu , B., Erd \'e lyi , R., and De Moortel , I. (2005). How to Channel Photospheric Oscillations into the Corona . 624, L61--L64. doi:10.1086/430345 2005ApJ...624L..61D

    2005 doi

  3. [11]

    Deforest , C. E. and Gurman , J. B. (1998). Observation of Quasi-periodic Compressive Waves in Solar Polar Plumes . 501, L217. doi:10.1086/311460 1998ApJ...501L.217D

    1998 doi

  4. [12]

    Erd \'e lyi , R. (2006). Magnetic seismology of the lower solar atmosphere . In Proceedings of SOHO 18/GONG 2006/HELAS I, Beyond the spherical Sun. vol. 624 of ESA Special Publication, 15.1 2006ESASP.624E..15E

    2006

  5. [13]

    Hannah , I. G. and Kontar , E. P. (2012). Differential emission measures from the regularized inversion of Hinode and SDO data . 539, A146. doi:10.1051/0004-6361/201117576 2012A&A...539A.146H

    2012 doi

  6. [14]

    B., De Moortel , I., Mathioudakis , M., Christian , D

    Jess , D. B., De Moortel , I., Mathioudakis , M., Christian , D. J., Reardon , K. P., Keys , P. H., et al. (2012). The Source of 3 Minute Magnetoacoustic Oscillations in Coronal Fans . 757, 160. doi:10.1088/0004-637X/757/2/160 2012ApJ...757..160J

    2012 doi

  7. [15]

    B., Dillon , C

    Jess , D. B., Dillon , C. J., Kirk , M. S., Reale , F., Mathioudakis , M., Grant , S. D. T., et al. (2019). Statistical Signatures of Nanoflare Activity. I. Monte Carlo Simulations and Parameter-space Exploration . 871, 133. doi:10.3847/1538-4357/aaf8ae 2019ApJ...871..133J

    2019 doi

  8. [16]

    Khomenko , E., Centeno , R., Collados , M., and Trujillo Bueno , J. (2008). Channeling 5 Minute Photospheric Oscillations into the Solar Outer Atmosphere through Small-Scale Vertical Magnetic Flux Tubes . 676, L85. doi:10.1086/587057 2008ApJ...676L..85K

    2008 doi

  9. [17]

    W., and Whittaker , I

    Kiddie , G., De Moortel , I., Del Zanna , G., McIntosh , S. W., and Whittaker , I. (2012). Propagating Disturbances in Coronal Loops: A Detailed Analysis of Propagation Speeds . 279, 427--452. doi:10.1007/s11207-012-0042-5 2012SoPh..279..427K

    2012 doi

  10. [18]

    A., Tanner , S

    Klimchuk , J. A., Tanner , S. E. M., and De Moortel , I. (2004). Coronal Seismology and the Propagation of Acoustic Waves along Coronal Loops . 616, 1232--1241. doi:10.1086/425122 2004ApJ...616.1232K

    2004 doi

  11. [19]

    (2012 a )

    Krishna Prasad , S., Banerjee , D., and Singh , J. (2012 a ). Oscillations in Active Region Fan Loops: Observations from EIS/ Hinode and AIA/SDO . 281, 67--85. doi:10.1007/s11207-012-0098-2 2012SoPh..281...67K

    2012 doi

  12. [20]

    Krishna Prasad , S., Banerjee , D., and Van Doorsselaere , T. (2014). Frequency-dependent Damping in Propagating Slow Magneto-acoustic Waves . 789, 118. doi:10.1088/0004-637X/789/2/118 2014ApJ...789..118K

    2014 doi

  13. [21]

    (2012 b )

    Krishna Prasad , S., Banerjee , D., Van Doorsselaere , T., and Singh , J. (2012 b ). Omnipresent long-period intensity oscillations in open coronal structures . 546, A50. doi:10.1051/0004-6361/201219885 2012A&A...546A..50K

    2012 doi

  14. [22]

    B., and Khomenko , E

    Krishna Prasad , S., Jess , D. B., and Khomenko , E. (2015). On the Source of Propagating Slow Magnetoacoustic Waves in Sunspots . 812, L15. doi:10.1088/2041-8205/812/1/L15 2015ApJ...812L..15K

    2015 doi

  15. [23]

    B., Van Doorsselaere , T., Verth , G., Morton , R

    Krishna Prasad , S., Jess , D. B., Van Doorsselaere , T., Verth , G., Morton , R. J., Fedun , V., et al. (2017). The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere . 847, 5. doi:10.3847/1538-4357/aa86b5 2017ApJ...847....5K

    2017 doi

  16. [24]

    O., Van Doorsselaere , T., Magyar , N., and Jess , D

    Krishna Prasad , S., Raes , J. O., Van Doorsselaere , T., Magyar , N., and Jess , D. B. (2018). The Polytropic Index of Solar Coronal Plasma in Sunspot Fan Loops and Its Temperature Dependence . 868, 149. doi:10.3847/1538-4357/aae9f5 2018ApJ...868..149K

    2018 doi

  17. [25]

    R., Title , A

    Lemen , J. R., Title , A. M., Akin , D. J., Boerner , P. F., Chou , C., Drake , J. F., et al. (2012). The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) . 275, 17--40. doi:10.1007/s11207-011-9776-8 2012SoPh..275...17L

    2012 doi

  18. [26]

    Mandal , S., Magyar , N., Yuan , D., Van Doorsselaere , T., and Banerjee , D. (2016). Forward Modeling of Propagating Slow Waves in Coronal Loops and Their Frequency-dependent Damping . 820, 13. doi:10.3847/0004-637X/820/1/13 2016ApJ...820...13M

    2016 doi

  19. [27]

    Markwardt , C. B. (2009). Non-linear Least-squares Fitting in IDL with MPFIT . In Astronomical Data Analysis Software and Systems XVIII, eds. D. A. Bohlender , D. Durand , and P. Dowler . vol. 411 of Astronomical Society of the Pacific Conference Series, 251 2009ASPC..411..251M

    2009

  20. [28]

    S., De Moortel , I., and Walsh , R

    Marsh , M. S., De Moortel , I., and Walsh , R. W. (2011). Observed Damping of the Slow Magnetoacoustic Mode . 734, 81. doi:10.1088/0004-637X/734/2/81 2011ApJ...734...81M

    2011 doi

  21. [29]

    Ofman , L., Romoli , M., Poletto , G., Noci , G., and Kohl , J. L. (1997). Ultraviolet Coronagraph Spectrometer Observations of Density Fluctuations in the Solar Wind . 491, L111. doi:10.1086/311067 1997ApJ...491L.111O

    1997 doi

  22. [30]

    D., Thompson , B

    Pesnell , W. D., Thompson , B. J., and Chamberlin , P. C. (2012). The Solar Dynamics Observatory (SDO) . 275, 3--15. doi:10.1007/s11207-011-9841-3 2012SoPh..275....3P

    2012 doi

  23. [31]

    Spruit , H. C. (1991). Absorption of p-Mode Waves by Magnetic Fields . In Challenges to Theories of the Structure of Moderate-Mass Stars, eds. D. Gough and J. Toomre . vol. 388 of Lecture Notes in Physics, Berlin Springer Verlag, 121--134. doi:10.1007/3-540-54420-8\_58 1991LNP...

    1991 doi

  24. [32]

    Van Doorsselaere , T., Wardle , N., Del Zanna , G., Jansari , K., Verwichte , E., and Nakariakov , V. M. (2011). The First Measurement of the Adiabatic Index in the Solar Corona Using Time-dependent Spectroscopy of Hinode/EIS Observations . 727, L32. doi:10.1088/2041-8205/727/...

    2011 doi

  25. [33]

    Wang , T. (2011). Standing Slow-Mode Waves in Hot Coronal Loops: Observations, Modeling, and Coronal Seismology . 158, 397--419. doi:10.1007/s11214-010-9716-1 2011SSRv..158..397W

    2011 doi

  26. [34]

    Wang , T., Ofman , L., Sun , X., Provornikova , E., and Davila , J. M. (2015). Evidence of Thermal Conduction Suppression in a Solar Flaring Loop by Coronal Seismology of Slow-mode Waves . 811, L13. doi:10.1088/2041-8205/811/1/L13 2015ApJ...811L..13W

    2015 doi

  27. [35]

    K., and Davila , J

    Wang , T., Ofman , L., Sun , X., Solanki , S. K., and Davila , J. M. (2018). Effect of Transport Coefficients on Excitation of Flare-induced Standing Slow-mode Waves in Coronal Loops . 860, 107. doi:10.3847/1538-4357/aac38a 2018ApJ...860..107W

    2018 doi

  28. [36]

    R., Tarbell , T

    Wuelser , J.-P., Lemen , J. R., Tarbell , T. D., Wolfson , C. J., Cannon , J. C., Carpenter , B. A., et al. (2004). EUVI: the STEREO-SECCHI extreme ultraviolet imager . In Telescopes and Instrumentation for Solar Astrophysics, eds. S. Fineschi and M. A. Gummin . vol. 5171 of ,...

    2004 doi

  29. [37]

    and Nakariakov , V

    Yuan , D. and Nakariakov , V. M. (2012). Measuring the apparent phase speed of propagating EUV disturbances . 543, A9. doi:10.1051/0004-6361/201218848 2012A&A...543A...9Y

    2012 doi

  30. [38]

    I., Kolotkov , D

    Zavershinskii , D. I., Kolotkov , D. Y., Nakariakov , V. M., Molevich , N. E., and Ryaschikov , D. S. (2019). Quasi-periodicity of magnetoacoustic waves in a plasma with heating/cooling misbalance . PPCF Under review Priv_Comm_Kolotkov

    2019

Pith tools

Reviewed August 14, 2026 · model on record in the stance chip above.