pith. sign in

arxiv: 2605.13635 · v1 · pith:ELTLOX4Tnew · submitted 2026-05-13 · 🌌 astro-ph.GA

Tracing the sulfur depletion in starless and pre-stellar cores

L. Sch\"oller , S. Spezzano , O. Sipil\"a , E. I. Makarenko , P.Caselli , H. A. Bunn , S. S. Jensen This is my paper

Pith reviewed 2026-05-14 18:04 UTC · model grok-4.3

classification 🌌 astro-ph.GA
keywords sulfur depletionstarless corespre-stellar coresmolecular abundanceschemical modelsTaurus Molecular Cloudsulfur chemistrydense cores
0
0 comments X

The pith

Sulfur-bearing molecule abundances in starless cores vary due to local environmental conditions rather than a uniform evolutionary path.

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

This paper measures abundances of 13 sulfur-bearing molecules in nine starless and pre-stellar cores in the Taurus Molecular Cloud. It compares these abundances and six ratios to three evolutionary tracers: H2 column density, the N2D+/N2H+ ratio, and the CO depletion factor. The observations reveal significant variations across cores, with some carbon- and oxygen-bearing ratios decreasing with density and deuteration but others showing weak or no correlation. 0D chemical models reproduce certain species like OCS and H2CS reasonably well but cannot match the full set simultaneously. The results indicate that sulfur chemistry cannot be described by any single evolutionary parameter and is instead strongly shaped by local conditions.

Core claim

The central claim is that the variations in abundances across the cores and the lack of consistent correlations with evolutionary tracers imply that no single parameter can describe sulfur chemistry, and that local environmental conditions strongly influence the observed abundances of sulfur-bearing molecules.

What carries the argument

Comparison of observed abundances and ratios (such as CCS/34SO and C34S/34SO) to evolutionary tracers (H2 column density, N2D+/N2H+, CO depletion factor) and 0D chemical models with varying initial sulfur abundances.

If this is right

  • Ratios tracing carbon- and oxygen-bearing species decrease with increasing H2 column density and N2D+/N2H+ ratio.
  • 0D models reproduce OCS, H2CS, and HDCS reasonably well but fail to match all species simultaneously, especially between carbon- and oxygen-bearing molecules.
  • Reproducing the full sample requires improved chemical networks and models that account for the core's physical structure.
  • Local environmental conditions must be considered to explain differences such as low abundances in L1517B versus enhanced oxygen-bearing species in L1495B.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Observations in cores from other molecular clouds could test whether environmental influences on sulfur chemistry are universal.
  • Incorporating 3D physical structures into chemical models might resolve discrepancies between carbon- and oxygen-bearing species.
  • Filamentary environments may systematically enhance certain oxygen-bearing sulfur species, suggesting targeted follow-up in similar regions.
  • Sulfur depletion mechanisms likely operate differently on small scales within the same cloud, affecting interpretations of total sulfur budgets.

Load-bearing premise

The chosen evolutionary tracers adequately capture the chemical history of the cores and that 0D models with adjusted initial sulfur abundances can represent the cores' physical structure and time evolution.

What would settle it

A larger sample of cores showing consistent correlations between abundances of all sulfur species and one single evolutionary tracer such as the CO depletion factor.

Figures

Figures reproduced from arXiv: 2605.13635 by E. I. Makarenko, H. A. Bunn, L. Sch\"oller, O. Sipil\"a, P.Caselli, S. S. Jensen, S. Spezzano.

Figure 1
Figure 1. Figure 1: Spectra of molecules observed toward the dust peak of the starless core L1495A-S (in black). The red line indicates the best [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Molecular abundances as a function of the H [PITH_FULL_IMAGE:figures/full_fig_p007_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Same as Figure [PITH_FULL_IMAGE:figures/full_fig_p008_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Same as Figure [PITH_FULL_IMAGE:figures/full_fig_p009_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Molecular abundance ratios probing isotopic fractionation as a function of the three evolutionary tracers. For clarity, the [PITH_FULL_IMAGE:figures/full_fig_p010_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Same as Figure [PITH_FULL_IMAGE:figures/full_fig_p011_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: Same as Figure [PITH_FULL_IMAGE:figures/full_fig_p011_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: Comparison between the observational data and the model abundance at three di [PITH_FULL_IMAGE:figures/full_fig_p013_8.png] view at source ↗
read the original abstract

Sulfur is one of the most abundant elements in the Universe, yet the sulfur budget inferred from the observed sulfur-bearing molecules in dense cores is significantly lower than expected. Starless and pre-stellar cores represent the earliest stages of star formation and provide a laboratory for studying the physical and chemical processes that cause sulfur depletion. We aim to constrain sulfur chemistry in dense cores by measuring abundances of sulfur-bearing molecules and how they reflect core evolution and environmental effects. We observed nine cores in the Taurus Molecular Cloud, targeting 13 sulfur-bearing molecules, including CS, CCS, C$_3$S, OCS, SO, SO$_2$, H$_2$CS, and isotopologs. Molecular abundances and six abundance ratios were compared to three evolutionary tracers: H$_2$ column density, N$_2$D$^+$/N$_2$H$^+$, and the CO depletion factor. We also compared observations with 0D chemical models with different initial sulfur abundances. We find variations in abundances across cores. L1517B exhibits low abundances and a high depletion factor, whereas L1495B shows enhanced levels in oxygen-bearing species within the L1495 filament. Ratios tracing carbon- and oxygen-bearing species (CCS/$^{34}$SO and C$^{34}$S/$^{34}$SO) decrease with increasing H$_2$ column density and N$_2$D$^+$/N$_2$H$^+$ ratio. Other species and ratios show weak or no correlation with tracers. Models reproduce OCS, H$_2$CS, and HDCS reasonably well, but not all species simultaneously, especially between carbon- and oxygen-bearing molecules. The variations and lack of consistent correlations suggest that a single evolutionary parameter cannot describe sulfur chemistry and that the local environmental conditions strongly influence the observed abundances. Reproducing the full sample of sulfur-bearing molecules would require improved chemical networks and models that account for the core's physical structure.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Axiom & Free-Parameter Ledger

1 free parameters · 1 axioms · 0 invented entities

The central claim rests on the validity of the three evolutionary tracers and the representativeness of 0D chemical models; initial sulfur abundance is adjusted per model run.

free parameters (1)
  • initial sulfur abundance
    Varied across model runs to attempt to match observed abundances of different species.
axioms (1)
  • domain assumption 0D chemical model assumptions hold for the cores
    Models ignore spatial structure and time-dependent physical evolution of the cores.

pith-pipeline@v0.9.0 · 5690 in / 1205 out tokens · 36767 ms · 2026-05-14T18:04:25.789114+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

73 extracted references · 73 canonical work pages

  1. [1]

    2014, in Protostars and Planets VI, ed

    André, P., Di Francesco, J., Ward-Thompson, D., et al. 2014, in Protostars and Planets VI, ed. H. Beuther, R. S. Klessen, C. P. Dullemond, & T. Henning, 27–51

    work page 2014

  2. [2]

    M., & Grevesse, N

    Asplund, M., Amarsi, A. M., & Grevesse, N. 2021, A&A, 653, A141

    work page 2021

  3. [3]

    & Pérez Gutiérrez, M

    Bachiller, R. & Pérez Gutiérrez, M. 1997, ApJ, 487, L93

    work page 1997

  4. [4]

    P., Kirchhoff, W

    Beers, Y ., Klein, G. P., Kirchhoff, W. H., & Johnson, D. R. 1972, J. Mol. Spec- trosc., 44, 553

    work page 1972

  5. [5]

    Bogey, M., Demuynck, C., & Destombes, J. L. 1982, J. Mol. Spectrosc., 95, 35

    work page 1982

  6. [6]

    N., Shingledecker, C

    Byrne, A. N., Shingledecker, C. N., Bergin, E. A., et al. 2026, ApJ, 998, 95

    work page 2026

  7. [7]

    & Ceccarelli, C

    Caselli, P. & Ceccarelli, C. 2012, A&A Rev., 20, 56

    work page 2012

  8. [8]

    M., Tafalla, M., Dore, L., & Myers, P

    Caselli, P., Walmsley, C. M., Tafalla, M., Dore, L., & Myers, P. C. 1999, ApJ, 523, L165

    work page 1999

  9. [9]

    M., et al

    Cazaux, S., Carrascosa, H., Muñoz Caro, G. M., et al. 2022, A&A, 657, A100

    work page 2022

  10. [10]

    2014, ApJ, 790, L1

    Ceccarelli, C., Dominik, C., López-Sepulcre, A., et al. 2014, ApJ, 790, L1

    work page 2014

  11. [11]

    2018, ApJ, 863, 126

    Chantzos, J., Spezzano, S., Caselli, P., et al. 2018, ApJ, 863, 126

    work page 2018

  12. [12]

    Clark, W. W. & De Lucia, F. C. 1976, J. Mol. Spectrosc., 60, 332

    work page 1976

  13. [13]

    I., Bergin, E

    Cleeves, L. I., Bergin, E. A., Alexander, C. M. O. D., et al. 2014, Sci., 345, 1590

    work page 2014

  14. [14]

    2025, A&A, 696, A219

    Codella, C., Bianchi, E., Podio, L., et al. 2025, A&A, 696, A219

    work page 2025

  15. [15]

    M., et al

    Crapsi, A., Caselli, P., Walmsley, C. M., et al. 2005, ApJ, 619, 379

    work page 2005

  16. [16]

    1999, ApJS, 125, 237

    Dalgarno, A., Yan, M., & Liu, W. 1999, ApJS, 125, 237

    work page 1999

  17. [17]

    N., Schroeder I, I

    Drozdovskaya, M. N., Schroeder I, I. R. H. G., Rubin, M., et al. 2021, MNRAS, 500, 4901

    work page 2021

  18. [18]

    Dubrulle, A., Demaison, J., Burie, J., & Boucher, D. 1980, Z. Naturforsch. A, 35, 471

    work page 1980

  19. [19]

    2024, A&A, 689, L7

    Dutrey, A., Chapillon, E., Guilloteau, S., et al. 2024, A&A, 689, L7

    work page 2024

  20. [20]

    H., Stutzki, J., & Wiedner, M

    Emprechtinger, M., Caselli, P., V olgenau, N. H., Stutzki, J., & Wiedner, M. C. 2009, A&A, 493, 89

    work page 2009

  21. [21]

    B., Tercero, B., Cernicharo, J., et al

    Esplugues, G. B., Tercero, B., Cernicharo, J., et al. 2013, A&A, 556, A143

    work page 2013

  22. [22]

    J., Dunham, M

    Evans, II, N. J., Dunham, M. M., Jørgensen, J. K., et al. 2009, ApJS, 181, 321

    work page 2009

  23. [23]

    2025, A&A, 700, A266

    Faure, A., Bacmann, A., & Jacquot, R. 2025, A&A, 700, A266

    work page 2025

  24. [24]

    A., Langer, W

    Frerking, M. A., Langer, W. D., & Wilson, R. W. 1982, ApJ, 262, 590

    work page 1982

  25. [25]

    2023, A&A, 670, A114

    Fuente, A., Rivière-Marichalar, P., Beitia-Antero, L., et al. 2023, A&A, 670, A114

    work page 2023

  26. [26]

    Galli, P. A. B., Loinard, L., Bouy, H., et al. 2019, A&A, 630, A137

    work page 2019

  27. [27]

    Goldsmith, P. F. & Langer, W. D. 1999, ApJ, 517, 209 Güdel, M., Briggs, K. R., Arzner, K., et al. 2007, A&A, 468, 353

    work page 1999

  28. [28]

    & Tafalla, M

    Hacar, A. & Tafalla, M. 2011, A&A, 533, A34

    work page 2011

  29. [29]

    2013, A&A, 554, A55

    Hacar, A., Tafalla, M., Kauffmann, J., & Kovács, A. 2013, A&A, 554, A55

    work page 2013

  30. [30]

    A., Millar, T

    Hatchell, J., Thompson, M. A., Millar, T. J., & MacDonald, G. H. 1998, A&A, 338, 713

    work page 1998

  31. [31]

    & van Dishoeck, E

    Herbst, E. & van Dishoeck, E. F. 2009, ARA&A, 47, 427

    work page 2009

  32. [32]

    2022, A&A, 658, A168

    Hily-Blant, P., Pineau des Forêts, G., Faure, A., & Lique, F. 2022, A&A, 658, A168

    work page 2022

  33. [33]

    & Wakelam, V

    Iqbal, W. & Wakelam, V . 2018, A&A, 615, A20

    work page 2018

  34. [34]

    S., Spezzano, S., Caselli, P., Grassi, T., & Haugbølle, T

    Jensen, S. S., Spezzano, S., Caselli, P., Grassi, T., & Haugbølle, T. 2023, A&A, 675, A34 Jiménez-Serra, I., Vasyunin, A. I., Caselli, P., et al. 2016, ApJ, 830, L6

    work page 2023

  35. [35]

    2003, ApJ, 582, 262

    Klapper, G., Surin, L., Lewen, F., et al. 2003, ApJ, 582, 262

    work page 2003

  36. [36]

    Laas, J. C. & Caselli, P. 2019, A&A, 624, A108

    work page 2019

  37. [37]

    I., et al

    Lattanzi, V ., Bizzocchi, L., Vasyunin, A. I., et al. 2020, A&A, 633, A118

    work page 2020

  38. [38]

    W., Myers, P

    Lee, C. W., Myers, P. C., & Tafalla, M. 1999, ApJ, 526, 788

    work page 1999

  39. [39]

    W., Myers, P

    Lee, C. W., Myers, P. C., & Tafalla, M. 2001, ApJS, 136, 703

    work page 2001

  40. [40]

    Lovas, F. J. 1985, J. Phys. Chem. Ref. Data, 14, 395

    work page 1985

  41. [41]

    Mangum, J. G. & Shirley, Y . L. 2015, PASP, 127, 266 Margulès, L., Lewen, F., Winnewisser, G., Botschwina, P., & Müller, H. S. P. 2003, Phys. Chem. Chem. Phys., 5, 2770 Martín-Doménech, R., Jiménez-Serra, I., Muñoz Caro, G. M., et al. 2016, A&A, 585, A112

    work page 2015

  42. [42]

    N., Savage, C., Brewster, M

    Milam, S. N., Savage, C., Brewster, M. A., Ziurys, L. M., & Wyckoff, S. 2005, ApJ, 634, 1126

    work page 2005

  43. [43]

    1997, ApJ, 491, L63 Müller, H

    Minowa, H., Satake, M., Hirota, T., et al. 1997, ApJ, 491, L63 Müller, H. S. P., Thorwirth, S., Roth, D. A., & Winnewisser, G. 2001, A&A, 370, L49

    work page 1997

  44. [44]

    Myers, P. C. 2009, ApJ, 700, 1609

    work page 2009

  45. [45]

    2019, A&A, 630, A136

    Nagy, Z., Spezzano, S., Caselli, P., et al. 2019, A&A, 630, A136

    work page 2019

  46. [46]

    Penzias, A. A. 1981, ApJ, 249, 518

    work page 1981

  47. [47]

    2005, in SF2A-2005: Semaine de l’Astrophysique Francaise, ed

    Pety, J. 2005, in SF2A-2005: Semaine de l’Astrophysique Francaise, ed. F. Ca- soli, T. Contini, J.-M. Hameury, & L. Pagani, 72

    work page 2005

  48. [48]

    M., Poynter, R

    Pickett, H. M., Poynter, R. L., Cohen, E. A., et al. 1998, J. Quant. Spectrosc. Radiat. Transf., 60, 883

    work page 1998

  49. [49]

    2020, Sci., 367, aaw7462

    Poch, O., Istiqomah, I., Quirico, E., et al. 2020, Sci., 367, aaw7462

    work page 2020

  50. [50]

    D., Clark, P

    Priestley, F. D., Clark, P. C., Glover, S. C. O., et al. 2023, MNRAS, 524, 5971

    work page 2023

  51. [51]

    D., Clark, P

    Priestley, F. D., Clark, P. C., Glover, S. C. O., et al. 2024, MNRAS, 531, 4408

    work page 2024

  52. [52]

    M., Padgett, D

    Rebull, L. M., Padgett, D. L., McCabe, C.-E., et al. 2010, ApJS, 186, 259

    work page 2010

  53. [53]

    P., Hartquist, T

    Ruffle, D. P., Hartquist, T. W., Caselli, P., & Williams, D. A. 1999, MNRAS, 306, 691

    work page 1999

  54. [54]

    1987, ApJ, 317, L115 Schöier, F

    Saito, S., Kawaguchi, K., Yamamoto, S., et al. 1987, ApJ, 317, L115 Schöier, F. L., van der Tak, F. F. S., van Dishoeck, E. F., & Black, J. H. 2005, A&A, 432, 369

    work page 1987

  55. [55]

    N., Caselli, P., et al

    Scibelli, S., Drozdovskaya, M. N., Caselli, P., et al. 2025, A&A, 702, A127

    work page 2025

  56. [56]

    2021, MNRAS, 504, 5754

    Scibelli, S., Shirley, Y ., Vasyunin, A., & Launhardt, R. 2021, MNRAS, 504, 5754

    work page 2021

  57. [57]

    N., Lamberts, T., Laas, J

    Shingledecker, C. N., Lamberts, T., Laas, J. C., et al. 2020, ApJ, 888, 52 Sipilä, O., Caselli, P., & Harju, J. 2015, A&A, 578, A55 Sipilä, O., Caselli, P., & Harju, J. 2019, A&A, 631, A63

    work page 2020

  58. [58]

    Slavicinska, K., Boogert, A. C. A., Tychoniec, Ł., et al. 2025, A&A, 693, A146

    work page 2025

  59. [59]

    M., & Lattanzi, V

    Spezzano, S., Caselli, P., Bizzocchi, L., Giuliano, B. M., & Lattanzi, V . 2017, A&A, 606, A82 Stäuber, P., Doty, S. D., van Dishoeck, E. F., & Benz, A. O. 2005, A&A, 440, 949

    work page 2017

  60. [60]

    1992, ApJ, 392, 551

    Suzuki, H., Yamamoto, S., Ohishi, M., et al. 1992, ApJ, 392, 551

    work page 1992

  61. [61]

    C., Caselli, P., Walmsley, C

    Tafalla, M., Myers, P. C., Caselli, P., Walmsley, C. M., & Comito, C. 2002, ApJ, 569, 815

    work page 2002

  62. [62]

    C., et al

    Tafalla, M., Santiago-García, J., Myers, P. C., et al. 2006, A&A, 455, 577

    work page 2006

  63. [63]

    Tieftrunk, A., Pineau des Forets, G., Schilke, P., & Walmsley, C. M. 1994, A&A, 289, 579

    work page 1994

  64. [64]

    Tiemann, E. 1974, J. Phys. Chem. Ref. Data, 3, 259 van Gelder, M. L., Tabone, B., Tychoniec, Ł., et al. 2020, A&A, 639, A87

    work page 1974

  65. [65]

    2018, MNRAS, 478, 5514

    Vastel, C., Quénard, D., Le Gal, R., et al. 2018, MNRAS, 478, 5514

    work page 2018

  66. [66]

    2004, A&A, 422, 159

    Wakelam, V ., Caselli, P., Ceccarelli, C., Herbst, E., & Castets, A. 2004, A&A, 422, 159

    work page 2004

  67. [67]

    2006, A&A, 451, 551

    Wakelam, V ., Herbst, E., & Selsis, F. 2006, A&A, 451, 551

    work page 2006

  68. [68]

    1999, MNRAS, 305, 143

    Ward-Thompson, D., Motte, F., & Andre, P. 1999, MNRAS, 305, 143

    work page 1999

  69. [69]

    D., & Velusamy, T

    Willacy, K., Langer, W. D., & Velusamy, T. 1998, ApJ, 507, L171

    work page 1998

  70. [70]

    Wilson, T. L. & Rood, R. 1994, ARA&A, 32, 191

    work page 1994

  71. [71]

    M., Occhiogrosso, A., Viti, S., et al

    Woods, P. M., Occhiogrosso, A., Viti, S., et al. 2015, MNRAS, 450, 1256

    work page 2015

  72. [72]

    1987, ApJ, 317, L119

    Yamamoto, S., Saito, S., Kawaguchi, K., et al. 1987, ApJ, 317, L119

    work page 1987

  73. [73]

    E., Yang, Y .-l., Zhang, Y ., et al

    Zhang, Z. E., Yang, Y .-l., Zhang, Y ., et al. 2023, ApJ, 946, 113 Article number, page 15 of 21 A&A proofs:manuscript no. aa60000-26 Appendix A: Plots of observed spectra Figures A.1 - A.8 show the observed spectra of all sulfur-bearing molecules including a Gaussian Fit toward all sources in the sample. Fig. A.1: Same as Figure 1 but for the starless co...

    work page 2023