Period Variation Rates of Four Radial Single-Mode High-Amplitude Delta Scuti Stars
Jaymie Matthews
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsReview Report
Article Title: Period variation rates of 4 radial single-mode high amplitude delta Scuti stars
Authors: Tian-Fang Ma, Jia-Shu Niu, Hui-Fang Xue
This manuscript provides a comprehensive analysis of the period variations of four radial single-mode high amplitude delta Scuti stars (HADS) using the O−C method. The study is well-conducted, with clear and organized results that offer valuable insights into the evolutionary stages and mechanisms of period variations in these stars.
However, the appendix contains excessive tables, which may overwhelm readers and detract from the key findings. The authors should summarize the data and present only the most relevant information in the appendix, with detailed data provided as supplementary material.
Overall, this article makes a valuable contribution to stellar astronomy. The comprehensive data analysis and clear presentation of results enhance the literature on HADS. While the quality of figures and tables can be improved, this does not significantly detract from the research's overall value.
I recommend publishing this article in "Universe" with minor revisions to address the issues related to figure and table quality.
Comments on the Quality of English Language
The language is written well but needs to be improved.
Author Response
This manuscript provides a comprehensive analysis of the period variations of four radial singlemode high amplitude delta Scuti stars (HADS) using the O−C method. The study is well-conducted, with clear and organized results that offer valuable insights into the evolutionary stages and mechanisms of period variations in these stars.
However, the appendix contains excessive tables, which may overwhelm readers and detract from the key findings. The authors should summarize the data and present only the most relevant information in the appendix, with detailed data provided as supplementary material.
Overall, this article makes a valuable contribution to stellar astronomy. The comprehensive data analysis and clear presentation of results enhance the literature on HADS. While the quality of figures and tables can be improved, this does not significantly detract from the research's overall value.

I recommend publishing this article in "Universe" with minor revisions to address the issues related to figure and table quality.
Reply: [
Thank you for your suggestions. In the revised version of the manuscript, we have removed the long tables in the appendix, collected them in a data file and uploaded it on the Zenodo website (https://zenodo.org/records/14950457).
Moreover, all the figures are all replotted in the revised manuscript.
Please see in the revised manuscript.
]
Reviewer 2 Report
Comments and Suggestions for AuthorsIt is a good paper and the results are finely presented.
Introduction, line 20: "... we called them HADS." Put High Amplitude Delta Scuti here.
Introduction, line 25: "...we can use the O − C method ..." Have one sentence to explain what it means. Observed - Calculating.
Introduction, line 49: "... of it’s period variation rate ..." It is "its".
4. Discussion, line 158: "... actrully caused by LTTE." 'ACTUALLY" You should also explain what LTTE is.
Appendices. You should have a file on a Web site for these data. Too much for the actual paper.
What is the evolutionary status of three delta Scuti stars.
The authors use the (O-C) method to do that, not other techniques. The authors use TESS data. It is not a new technique but it work for two stars.
It affirms evolutionary status of the two stars. The third star is still unknown.
Author Response
1. Introduction, line 20: "... we called them HADS." Put High Amplitude Delta Scuti here.
Reply: [
Thank you for pointing out the mistake. We have modified that in the revised manuscript.
]
2. Introduction, line 25: "...we can use the O - C method ..." Have one sentence to explain what it means. Observed - Calculating.
Reply: [
Thank you for the suggestion. We have added the explanation of the O-C method in the revised manuscript.
]
3. Introduction, line 49: "... of it’s period variation rate ..." It is "its".
Reply: [
Thank you for pointing out the mistake. We have modified that in the revised manuscript.
]
4. Discussion, line 158: "... actrully caused by LTTE." 'ACTUALLY" You should also explain what LTTE is.
Reply: [
Thank you for pointing out the mistakes. We have modified them in the revised manuscript.
]
5. Appendices. You should have a file on a Web site for these data. Too much for the actual paper.
Reply: [
Thank you for your suggestion, all the data have now been collected and uploaded on the Zenodo website (https://zenodo.org/records/14950457).
]
6. What is the evolutionary status of three delta Scuti stars.
The authors use the (O-C) method to do that, not other techniques. The authors use TESS data. It is not a new technique but it work for two stars.
It affirms evolutionary status of the two stars. The third star is still unknown.
Reply: [
If we ascribe the observed linear period variation rates to stellar evolution, it indicates that the star is in the post-MS evolutionary stage. However, some previous studies show discrepancy between the theoretical predictions and the observed values. This should be studied in-depth in future.
]
Reviewer 3 Report
Comments and Suggestions for AuthorsGeneral impressions
The manuscript investigates the period variations of four bright, high-amplitude delta Scuti stars using O-C diagrams. Some of the O-C data used are from the literature, a significant part is determined by the authors from the TESS space telescope and AAVSO light curves. The period variation rates are then determined from the O-Cs. In three cases (XX Cyg, YZ Boo, GP And), the resulting rates are similar to previously published ones. In the case of ZZ Mic, a negative period change was obtained, in contrast to previous studies, and indications of binarity were identified. As the manuscript is about bright, highly studied stars, it may be useful for future studies. Weaknesses in the presentation can be improved (see some suggestions below).
Specific comments
l. 24.
“...which exhibit only one radial mode,...”
This is a critical point. It was detected in all the stars studied. The work of Xue et al (2023, Res. Astron. Astrophys 23, 075002) should be mentioned and cited here.
l. 54.
“...was first reported by [25].”
What was reported? Maybe you mean “was discovered”.
2. Data sources and data reduction
This part is rather terse.
(i) In any case, a table showing the new observations would be necessary: which TESS sector data were used for which star, and also the time spans of AAVSO data. I understand that these can be extracted from the attached data files, but it would be much easier to overview.
(ii) About the TESS mission itself, 1-2 sentences should be written, with the usual reference (Ricker et al., 2015 JATIS 1, 014003). It should also be described what (exposure time) is meant by `short cadence' data.
(iii) That the TESS data were downloaded from the MAST portal is not clear to readers. Depending on the source, MAST offers several types of photometry for TESS. In this case, is it the SPOC photometry? If so, this should be indicated and cited appropriately (Caldwell et al. 2020 RNAA 4, id. 201)
l. 72.
“curve_fit” is the routine scipy.optimize.curve_fit? If so, write that and cite it as the Scipy manual asks.
l. 158.
“...is actrully...” is actually
“...by LTTE.” The acronym should be resolved at its first occurrence (here).
l. 163.
“...an F-test is performed...”
How? What program did you use for this? Please, specify.
l. 194.
Since this star, like all the others here, pulsates in a single radial mode (see note above to the line 24.), this note is irrelevant. It can be omitted.
l. 212.
“ ture...” true
Comments on the Quality of English LanguageI'm not a native speaker, but I did notice some unusual turns of language, the repetition of words, and sometimes even whole sentences. A proofreading by a native speaker would definitely be useful.
Author Response
Specific comments
1. l. 24. “...which exhibit only one radial mode,...” This is a critical point. It was detected in all the stars studied. The work of Xue et al (2023, Res. Astron. Astrophys 23, 075002) should be mentioned and cited here.
Reply: [
Thank you for your suggestion. We have added the reference in the revised manuscript.
]
2. l. 54. “...was first reported by [25].” What was reported? Maybe you mean “was discovered”.
Reply: [
Thank you for pointing out the mistake. We have modified the statement in the revised manuscript.
]
3. Data sources and data reduction
This part is rather terse.
(i) In any case, a table showing the new observations would be necessary: which TESS sector data were used for which star, and also the time spans of AAVSO data. I understand that these can be extracted from the attached data files, but it would be much easier to overview.
Reply: [
Thank you for your suggestion. We have added a table of the data overview (Table 1) in the revised manuscript.
]

(ii) About the TESS mission itself, 1-2 sentences should be written, with the usual reference (Ricker et al., 2015 JATIS 1, 014003). It should also be described what (exposure time) is meant by `short cadence' data.
Reply: [
Thank you for your suggestion. We have added the relevant description in the revised manuscript.
]

(iii) That the TESS data were downloaded from the MAST portal is not clear to readers. Depending on the source, MAST offers several types of photometry for TESS. In this case, is it the SPOC photometry? If so, this should be indicated and cited appropriately (Caldwell et al. 2020 RNAA 4, id. 201)
Reply: [
Thank you for your suggestion. We have added the relevant description in the revised manuscript.
]
4. l. 72. “curve_fit” is the routine scipy.optimize.curve_fit? If so, write that and cite it as the Scipy manual asks.
Reply: [
Thank you for your suggestion. We have modified the statement and added the reference in the revised manuscript.
]
5. l. 158.
“...is actrully...” is actually
“...by LTTE.” The acronym should be resolved at its first occurrence (here).
Reply: [
Thank you for pointing out the mistakes. We have modified them in the revised manuscript.
]
6. l. 163.
“...an F-test is performed...”
How? What program did you use for this? Please, specify.
Reply: [
Thank you for your suggestion. We have added some statement to explain the process of the F-test in this work.
Please see in the manuscript.
]
7. l. 194.
Since this star, like all the others here, pulsates in a single radial mode (see note above to the line 24.), this note is irrelevant. It can be omitted.
Reply: [
Thank you for your suggestion. We have removed the statement in the revised manuscript.
]
8. l. 212.
“ ture...” true
Reply: [
Thank you for pointing out the mistakes. We have modified them in the revised manuscript.
]
