The Infrared Extinction Law in the Ophiuchus Molecular Cloud Based on the UKIDSS and Spitzer c2d Surveys
Round 1
Reviewer 1 Report
Comments for author File: 
Comments.pdf
Author Response
Point 1: This paper overall is very good and should be published. However, there are a few issues I would like to bring to the attention of the authors, and after them I will list some improvements in the English.
The biggest issue I have is the paper misses a number of references: Harris, Woolf, & Rieke 1978 was the first effort to obtain an accurate extinction law for rho Oph
Gordon, Misselt, Bouwman et al. 2021 is a comprehensive look at infrared extinction laws and the results need to be compared with those in this work
Flaherty, Megeath, and Pipher 2007 is a widely cited study of extinction in star forming regions, including Ophiuchus, in the IRAC and MIPS Spitzer bands.
Vrba, Coyne, and Tapia 1993 is a comprehensive study of extinction in the rho Oph cloud.
Response 1: Thanks for the referee's positive assessment of our paper. We appreciate the valuable feedback and suggestions. The above citations have been added in the text.
Point 2: An obvious question is that the Harris study found that the water ice absorption at 3.1um seemed to come in at a certain extinction level, and this has been further studied by Tanaka, Sato, Nagata, and Yamamoto 1990 among others – and also in other clouds. It would be interesting to see if there are other changes in the extinction law at about the same point, and it would appear that these authors have the material to do that.
Response 2: We appreciate the referee's suggestion regarding the water ice absorption feature at 3.1 μm. In our study, we primarily focused on examining the overall behavior of the extinction law in the Ophiuchus cloud using the UKIDSS and Spitzer data. We agree that investigating potential changes in the extinction law at this particular wavelength is an interesting avenue. We hope to explore this question in future work.
Point 3: Line 131 – cites considerable difference between 2MASS and UKIDSS filters – this is confusing, since UKIDSS is calibrated relative to 2MASS. Some explanation should be given to explain why the filters still might be significantly different.
Response 3: We understand the confusion regarding this statement. While it is true that UKIDSS is indeed calibrated relative to 2MASS, there can still be differences between the filters used in the two surveys. In the study by Cambresy et al. (2011), systematic biases were found in the photometry between UKIDSS and 2MASS photometry. We added the explanation in the text of the revised paper.
Point 4: Line 161, T should be the relative response function, not the filter transmission. That is, it needs to include terms like the detector spectral response. This needs to be corrected.
Response 4: Thanks for pointing this out. The parameter T we used are from the SVO Filter Profile Service, which indeed represent the relative response function. It includes the filter transmission and quantum efficiency, etc. We updated the terminology to "relative response function" in the revised paper.
Point 5 : Here are some minor fixes for the English, which overall is really excellent. Line 67, should say “Ophiuchus cloud”
Line 69, deep data, not the deep data
Line 81, wavelengths, full widths
Line 96, two MIPS bands at not in
Line 98 [24] and [70] bands
Line 99 The data from the
Figure 1 caption the 2MASS, of the A_K map
Line 108, simultaneous seems like the wrong word
Line 111, missing of the pstar
Table 1 “for the Ophiuchus cloud”
Line 129, using the 2MASS
Figure 2 caption a stellar spectrum of a
Line 201 – 202 is an obvious place to reference Harris and Vrba
Line 207 – This paragraph is confusing because it mixes extinction in the diffuse ISM (e.g., Rieke et al.) with others in dense regions Although there is a disclaimer at the end, it would be better to distinguish the cases from the beginning.
Line 212 – need to reference Gordon et al., Harris, Flaherty, etc.
Figure 3, dashed lines, not dished lines, plus observed by both Spitzer and UKIDSS in the Ophiuchus Line 250 follows
Line 334 – how a denser environment promotes dust growth
Line 348, by relatively low
Lines 317 and 351 are repetitive
Line 382, color-excess ratios
Response 5:
Reviewer 2 Report
Report on the manuscript by Jun Li and Xi Chen “The Infrared Extinction Law in the Ophiuchus Molecular Cloud based on UKIDSS and Spitzer “
The clearly written paper discusses variability of the infrared extinction law depending on the environmental conditions. Authors combine the deep NIR and MIR data from Spitzer observations and study the extinction law in the Ophiuchus cloud. Author’s find that in 3 – 8 $\mu$m range the extinction law exhibits a flat behavior consistent with the previous studies while in the NIR- range the extinction demonstrates a steeper behavior . Results of the authors lend an additional support to the dust growth in the dense regions of the clouds. The paper is undoubtedly worthy of publication in the journal.
Author Response
Point 1: The clearly written paper discusses variability of the infrared extinction law depending on the environmental conditions. Authors combine the deep NIR and MIR data from Spitzer observations and study the extinction law in the Ophiuchus cloud. Author's find that in 3 - 8\mum range the extinction law exhibits a flat behavior consistent with the previous studies while in the NIR- range the extinction demonstrates a steeper behavior . Results of the authors lend an additional support to the dust growth in the dense regions of the clouds. The paper is undoubtedly worthy of publication in the journal.
Response 1:
Reviewer 3 Report
The extinction law in the Ophiucus cloud is found to be a flat MIR extinction as in previous studies.The authors decided to use NIR and MIR data obtained from the UKIDSS GCS and the Spitzer c2d survey. This choice is not well motivated, since new data are available on the region.
The introduction is in some part too general, more suitable for the thesis than a paper. I also found some plagiarism in the introduction.
This comment can be applied in different parts of the paper, as well as tables. A more quantitative, complete and updated introduction would help the motivation of the paper. The general introduction on so old instrument can just be shortened and specifying directly the properties of thee selected data.
A broader scientific reason for selecting the Ophiucus to make the study is not clear from the paper.
In the analysis no reference to the first 2MASS exctintion map of Ophiucus presented by Lombardi et al. 2008 using the well tested code NICEST.
Instead of showing in Fig.1 a 2MASS older extinction maps, the authors may show their improved map. A clear step in the angular resolution in this new analysis is not clearly stated.
The references are in general old but not always the most significant in the field.
Few sentences are not clear: checking the references they look like an interpolation of a general concept but been not really quantitative (e.g. beginning of sec. 3.2).
General comments for the discussion.
Apart of new data, there are also column density maps from Herschel that are neither mentioned in the discussion or Sanders+ 2022. Another new work in this field is a 3D maps possible from GAIA + e.g. 2MASS (e.g. Hottier +2020).
When giving the reference of even higher values of AJ/AK from the literature, there are values also from 1985 or 2005 without a clear motivation or the instruments used for these determination.
I would also suggest making the citations including the year of the publication in the text.
I strongly suggest to the authors to follow my general suggestions to make the paper publishable.
acceptable
Author Response
Point 1: The extinction law in the Ophiucus cloud is found to be a flat MIR extinction as in previous studies. The authors decided to use NIR and MIR data obtained from the UKIDSS GCS and the Spitzer c2d survey. This choice is not well motivated, since new data are available on the region.
Response 1: Thanks the referee for feedback. Our study focuses on investigating the IR extinction law within dense molecular clouds. The Ophiuchus cloud was chosen as our target due to its proximity, high galactic latitude location, and minimal foreground and background contamination. The UKIDSS GCS data utilized in our analysis were acquired from UKIRT, which is a prominent 4-meter class telescope dedicated to NIR surveys. We are aware that during the preparation of our manuscript, Meingast et al. (2023) released the VISIONS survey, based on another 4-meter class telescope, VISTA. However, the depth of both the UKIDSS GCS and VISIONS surveys is comparable. Furthermore, the Spitzer data is the best available MIR data for our analysis. In the future, we may explore the incorporation of data from the JWST data. Spitzer c2d survey covers the very large area (8 square degrees) of the Ophiuchus cloud, allowing for a more convenient study of variations in the extinction law within the same molecular cloud.
Point 2: The introduction is in some part too general, more suitable for the thesis than a paper. I also found some plagiarism in the introduction.
Response 2: We have carefully revised the introduction to ensure that it is appropriately tailored to the scope of a paper. Regarding the accusation of plagiarism, we want to assure that we have made every effort to appropriately cite and reference all relevant sources. However, we understand that there might be instances where some paragraphs or words might resemble existing works. I apologize for any unintentional similarity and we have carefully reviewed and revised the introduction and other sections to ensure originality and clarity.
Point 3: This comment can be applied in different parts of the paper, as well as tables. A more quantitative, complete and updated introduction would help the motivation of the paper. The general introduction on so old instrument can just be shortened and specifying directly the properties of thee selected data.
Response 3: In Section 2, we have shortened the introduction regarding these two surveys.
Point 4: A broader scientific reason for selecting the Ophiucus to make the study is not clear from the paper.
Response 4: We have revised the first and fourth paragraphs of Section 1 to give a clearer scientific justification.
Point 5: In the analvsis no reference to the first 2MASS exctintion map of Ophiucus presented by Lombardi et al. 2008 using the well tested code NICEST.
Response 5: This citation has been added to the text in Section 2.2.
Point 6: Instead of showing in Fig. 1 a 2MASS older extinction maps, the authors may show their improved map. A clear step in the angular resolution in this new analysis is not clearly stated.
Response 6: Thanks the referee for this valuable suggestion. Our main objective is to investigate the infrared extinction law in this work. Exploring the extinction map is also an intriguing aspect of our research. In future work, we plan to further investigate the high-resolution distribution of extinction based on the current understanding of the extinction law.
Point 7: The references are in general old but not always the most significant in the field.
Response 7: We have added some updated references in the revised manuscript.
Point 8: Few sentences are not clear: checking the references they look like an interpolation of a general concept but been not really quantitative (e.g. beginning of sec. 3.2).
Response 8: We have revised those sentences and the corresponding references to provide more specific and quantitative information to enhance the clarity.
Point 9: General comments for the discussion.
Apart of new data, there are also column density maps from Herschel that are neither mentioned in the discussion or Sanders+ 2022. Another new work in this field is a 3D maps possible from GAIA + e.g. 2MASS (e.g. Hottier +2020).
Response 9: Thanks for this suggestion, our reference to the extinction map is purely for illustrative purposes, indicating the spatial coverage of the survey data used. Regarding the 3D extinction map, the existing Gaia-based 3D extinction maps have limited depth and are not suitable for dense clouds like the Ophiuchus cloud. The investigation of the improved extinction is of great interest, we will further explore it in our future work.
Point 10: When giving the reference of even higher values of AJ/AK from the literature, there are values also from 1985 or 2005 without a clear motivation or the instruments used for these determination.
Response 10: More information has been adden in the end of Section 4.1 for clarity.
Point 11: I would also suggest making the citations including the year of the publication in the text.
Response 11: More updated citations have been added in the text.
Point 12: I strongly suggest to the authors to follow my general suggestions to make the paper publishable.
Response 12:
