Neutron Capture in Evolved Red Giants: A Review
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis paper accurately reviews the historical development of our current understanding of s-process nucleosynthesis, highlighting the interplay between stellar models, nuclear reaction theory, and observations. It is a comprehensive and pedagogical introduction to the topic of s-process, and it paints a faithful picture of our current understanding of s-process nucleosynthesis, highlighting the progress made as well as the remaining challenges for future research.
I fully support accepting this article for publication after the author has addressed a few minor comments. I also added "Minor Suggestions and Typos" for the author to consider. Regardless of whether they accept the suggestions or not, I believe the paper is ready for publication after the minor comments are addressed.
Minor Comments:
- I suggest spelling out thermal pulses in the abstract (and define the acronym)
- Abstract line 8: "I shall outline how neutron sources were discovered to be activated there and what observational constraints and nuclear measurements have taught us about the status of our theoretical models in this field of nuclear and stellar physics research".
I suggest breaking this into two sentences to make the purpose of the paper clearer. Something like: I shall outline how thermal pulses were discovered to be the site where neutron sources can be activated.
I will finally discuss what observational constraints and nuclear measurements have taught us about the status of our theoretical models of nuclear and stellar physics.
- Line 54: Define what N_s is, and perhaps split the sentence into two for clarity purposes
- Eq. 11: typo, 4 should be inside the parenthesis
- Eq. 12: wrong sign, thermal stability requires density and temperature to increase/decrease simultaneously
- Line 165: "As an example, in models of a 3M⊙ star". Specify that it is solar metallicity and also who made the model and where it is published (I assume it is from Ref. 24, make it explicit in the text).
- Figure 1: Explain the difference between black, blue, and red lines.
- It might be useful to highlight somewhere in section 4.2 that, despite the fact that the 22Ne(a,g) is not the source for the main component, it is still the dominant source in more massive stars.
- Figure 6: Make it clearer in the caption that the y-axis is the ratio between GCE results and model-independent estimates.
- I would rename section 5.1: Normal AGB Star, to make it clear that it is the AGB stars that are "normal", not the observations.
- Line 357: Define the acronyms in [hs/ls] as heavy and light s nuclei.
- Line 371: Include a reference or two on the i-process.
Minor Suggestions and Typos:
Line 22: "would" -> "could"
Line 31: "would actually" -> remove this
Line 45: Specify that reference 13 is CFHZ.
Line 49: remove period after [14]
Line 51: "complete description" -> "comprehensive description". It was not strictly speaking complete since many more details have been added since. Comprehensive seems more appropriate.
Line 56: "remains" -> "remain"
Line 77: "[15]," -> "[15]."
Line 92: "Thus, under equilibrium s processing" -> "Thus, when s-process nucleosynthesis proceeds in equilibrium"
Line 170: "As these events recur, helium burns above the core, made of C and O, which is characterized by a degenerate structure (a quantum Fermi gas)." -> "As these events recur, helium burns above the degenerate (i.e., a quantum Fermi gas) C--O core ."
Line 177: "release from" -> "released in"
Line 183: remove parentheses
Line 184-185: "Despite the occurrence of dredge up, the large envelope mass prevents stars on mass larger thatn 4-5 M⊙ to become C rich at the point that C dominates the photosphere composition and the formation of C-based molecules" -> "Despite the occurrence of dredge up, the large envelope mass prevents stars of mass larger than 4-5 M⊙ to become C rich to the point where C dominates the photospheric composition leading to the formation of C-based molecules"
Lien 200: "FRANEC" -> "code FRANEC"
Line 202: "at the left" -> "to the left"
Line 235: "metallity" -> "metallicity"
Line 251: "Urbana" -> "Urbana-Champaign"
line 257: close parenthesis
Line 291: "cobfirmed" -> "confirmed"
Line 312: "prsently" -> "presently"
Suggestion: stick to the same convention of not spelling out the element name: i.e., H burning instead of hydrogen burning, etc... everywhere.
Author Response
Comment 1 - I suggest spelling out thermal pulses in the abstract (and define the acronym)
Answer; this was done and acronyms defined everywhere.
Comment 2.
Abstract line 8: "I shall outline how neutron sources were discovered to be activated there and what observational constraints and nuclear measurements have taught us about the status of our theoretical models in this field of nuclear and stellar physics research".
I suggest breaking this into two sentences to make the purpose of the paper clearer. Something like: I shall outline how thermal pulses were discovered to be the site where neutron sources can be activated.
I will finally discuss what observational constraints and nuclear measurements have taught us about the status of our theoretical models of nuclear and stellar physics.
Answer. I followed these suggestions in detail.
Comment 3. Incudes various minor suggestions from line 54 to Figure 1.
Answer: I thank the referee for her/his accuracy in the reading. All corrections suggested have been done and recognized as pertinent.
Comment 4.
- It might be useful to highlight somewhere in section 4.2 that, despite the fact that the 22Ne(a,g) is not the source for the main component, it is still the dominant source in more massive stars.
Figure 6: Make it clearer in the caption that the y-axis is the ratio between GCE results and model-independent estimates.
Answer: corrected as required.
Comments n. 5. Includes various typos of mine and minor, but always useful indications, including a careful identfication of missprints.
Answer. I really appreciated such an accuracy. I followed the instructions and in particular expanded the discussion of the 22Ne source, adding more references.
All changes are indicated in bold in the new text.
Reviewer 2 Report
Comments and Suggestions for AuthorsHeavy elements produced in the s-process of the neutron-capture nuclear reactions play a key role in understanding stellar evolution and evolution of the Galactic matter, when observed stellar elemental abundances are confronted to the theory. The paper presents a nice historical review of the theoretical treatments of the main component of the s-process and describes a current status of the theory. The paper will be interesting and useful for many researchers working on the asymptotic giant branch stars or the Galactic chemical evolution. I recommend the paper for publication.
Minor remarks.
(i) Page 4: $\alpha$ in the formulas (10) to (12) is not defined.
(ii) Page 4: One needs to double check the formulas (7) to (11). I am unable to deduce the equation (11) using (7) to (10).
(iii) Figure 5, top panel: What does the dashed curve (exp) mean?
(iv) Several typos, for example, "GIANtS" in the title, "addrssed" (string 187), etc.
Author Response
Comment 1 - (Outlines some problems in the equations, from the definition of the parameter alpha in relation (10) to the general derivation of equation (12).
Answer: on these poins there a few unclarities, noticed also by refereee n. 1 and now corrected.
Comment 2. (on the dashed line in the top panel of figure 5).
Answer. The caption has been rephrased and should now be clear.
Comment 3 (on typos spread through the text).
Answer. I hope all these have now been corrected, also with the help of the first referee.
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsAnswering the remarks (i) and (ii), the author states: "on these poins there a few unclarities, noticed also by refereee n. 1 and now corrected." However, Sect. 3.1 is exactly the same in the initial and revised versions. There is no definition of $\alpha$ in the formulas (10) to (12). How the equation (11) was deduced from (7) to (10) is still unclear for me.
Answering the remark (iii), the author states: "The caption has been rephrased and should now be clear." But the caption of Figure 5 is exactly the same in the initial and revised versions. There is no definition of the dashed curve (exp) mean.
Minor remarks to the revised manuscript.
(v) String 55: "for nuclei -i heavier than 56Fe" - Why is the sign "-" here?
(vi) String 177-178: "above the degenerate core (the adjective indicating that its physics is the one of a quantum Fermi gas) C-O core" - Probably, the first "core" should be removed.
Author Response
Comment n. 1
Answering the remarks (i) and (ii), the author states: "on these poins there a few unclarities, noticed also by refereee n. 1 and now corrected." However, Sect. 3.1 is exactly the same in the initial and revised versions. There is no definition of $\alpha$ in the formulas (10) to (12). How the equation (11) was deduced from (7) to (10) is still unclear for me.
Answer:
I am very sorry of this misunderstanding with Referee n. 2. The strange fact is that the points she/he rises have been duely addressed. Did I make some mistakes in sending the revised version? Does he/she have my same text? I’ve better be boring, but clearer, on what I said, maybe too quickly, in my first reply.
- The definition of a is now contained in line 159, where in the revised version it is specified: “In general, if α and β are constant parameters…”. This means that the reasoning remains valid also for equations of states more general than that of a purely prefect gas.
- Then, as in the expression of Dm the density (for a fixed value of r) is proportional to 1/l. Equation (8) follows immediately.
- I shall now try to state the remaining formulation details in a more explicit form.
Comment 2. Answering the remark (iii), the author states: "The caption has been rephrased and should now be clear." But the caption of Figure 5 is exactly the same in the initial and revised versions. There is no definition of the dashed curve (exp) mean.
Answer: again, there must have been the transfer of a wrong text in place of my revised version. The comment was indeed addressed in some detail. My revised form of the caption of Figure 5, contains now the following further comment: “For comparison, in panel 1 the dashed line shows what would be the number of protons for a simple exponential-law penetration. This difference clarifies how low is the resulting abundance of 13C in the new approach. [75]”
Comment 3
Minor remarks to the revised manuscript.
(v) String 55: "for nuclei -i heavier than 56Fe" - Why is the sign "-" here?
(vi) String 177-178: "above the degenerate core (the adjective indicating that its physics is the one of a quantum Fermi gas) C-O core" - Probably, the first "core" should be removed.
Answers
- Indicating a nucleus i with the notation “-I” (hyphen i) is quite common in nuclear astrophysics papers. If the referee does not like it, the hyphen will now be removed.
- The repetition of “core” is actually a mistake of mine, introduced in the revised version. Thanks for noticing it. It has now been removed in the (hopefully final) text.
Round 3
Reviewer 2 Report
Comments and Suggestions for AuthorsIndeed, the previous revised version (galaxies-4295918-peer-review-v2.pdf) looked unfinished. In the today version (galaxies-4295918-peer-review-v3.pdf), I see that the equation (10) is correct, and my other remarks are taken into account.
