Scattered Radiation of Protoplanetary Disks
Round 1
Reviewer 1 Report
Overall, the reviewed manuscript is clear and well organized. My main comment is that it mostly focuses on UX Ori systems, while the title of the manuscript would suggest a broader topic. In particular, there is a very large amount of literature on scattered light images of protoplanetary disks in polarized light that were not mentioned by the author.
See, for example, Garufi et al. 2022, A&A, 658, 137, and references therein, just to cite one of the most recent papers.
In addition to this point, I have two comments related to the geometry of UX Ori systems:
1. In lines 34-35: " ... only small inclination of their CS disks ... ". The author should clarify what "small inclination" means. In particular, does "a small inclination" indicate a disk that is almost face-on or hedge-on?
2. In general, I find the geometry of UX Ori systems a bit confusing. In lines 33-35, the authors state that "UX Ori differ from photometrically inactive HAe stars only with a small inclination of their CS disks to the line-of-sight." I think this should be explained better. For example, in the case of CQ Tau, the CS disk has an inclination of 35-50 deg (see lines 209). However, there are other HAe disks with a similar inclination that do not exhibit UX Ori behavior. So, disk inclination cannot be the only important parameter. Also, in the case of CQ Tau, the author mention a change in inclination between the inner disk and the outer disk. But it is unclear how this fact relates to the UX Ori behavior. In conclusion, I think that the authors should clarify what they think is the most probable geometry of UX Ori systems. To this end, they might want to consider including a sketch if the disk geometry.
Author Response
Dear Reviewer,
Thank you for your comments on our paper, attached please find our reply to you.
Thanks,
Authors
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper presents a nice review of young stars and their circumstellar (CS) disks, in particular, using the linear polarization and brightness observations of scattered radiation to understand the nature of the CS disks. The topic is all the more important because the innermost regions of the disks are believed to be a place of planet formation. The authors are well-known experts in studies of young stars who made a great contribution to the field. For example, Grinin (1988) was first who pointed out an important role of the scattered radiation in understanding the nature of the young irregular variable stars. Therefore, the paper provides both an interesting historical overview and a description of modern methods of observations and their analysis. The paper will be useful for both experienced researchers who may find new ideas here and the beginners who can be excited by the problems that are awaiting the solution. I recommend the paper for publication in the Universe journal.
Minor remarks.
Page 1, string 25: the date 1986 has to be replaced with the right one, 1988.
Page 6, string 172 and caption of Fig. 5. Why are Fe II 5018, 5019 A lines indicated?
In the 5018 to 5019 A region, the only Fe II line can be measured in stellar spectra, namely, Fe II 5018.436 A (Eexc = 2.89 eV, log gf = -1.35 according to NIST). The other Fe II lines in this region arise from substantially higher excitation levels and have lower log gf.
Author Response
Dear Reviewer,
Thank you for your comments on our paper, attached please find our reply to you.
Thanks,
Authors
Author Response File: Author Response.pdf
