Physical Properties of Radio Stars Based on LAMOST Spectral Survey

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Author Response

Dear authors,

Your catalogue of information of radio stars could be of interest to the scientific community,

because of the possible connection to physical processes in stars as you indicate with references in l232-238. However this connection cannot be proven solely using the data derived. For the catalogue to be trustworthy the methods how the data is obtained and derived must be explained very well. Unfortunately this is not the case yet. So I encourage you to improve it for your results to be useful. Below I try to indicate some of these shortcomings.

Reply: Thank you for your perfect comments and suggestions on our manuscript again. We agreed with all your comments. We revised all of them. Here we send you our revised form of our manuscript again.

 

Abstract

L5 Lamost DR7 and L7 also 1319 medium resolution spectra of 156 radio stars …

DR7 is low resolution ?

Do you mean to say ?

Reply: For LAMOST DR7, there are two spectral surveys. One is low resolution spectral survey. The other is medium resolution spectral survey. We added several words to describe them. Thank you.

 

We cross-matched the big data from LAMOST DR7 low resolution spectral survey with a catalogue of radio stars, and obtained 449 stellar spectra of 258 stars. We detected 185 spectra with H alpha emissions. There are a total of 108 objects with repeated low resolution spectral observations, which 63 of them show variations of H alpha over a long time.

 

We also cross-matched LAMOST DR7 medium resolution spectra with the radio star catalog. We obtained 1,319 LAMOST medium-resolution spectra of 156 radio stars and calculated their equivalent widths (EWs) of the H alpha line. Among them, 93 radio stars with H alpha emissions were found through the LAMOST medium resolution spectra

 

“156 radio stars also had medium resolution spectra “ (Yes)

L8 “In addtion “  to what ?

Reply: I am sorry for our poor English. I mean that Among 156 radio stars with LAMOST medium spectra, 93 radio stars with H alpha emissions were found through the LAMOST medium resolution spectra.

 

L 11 - L12: seems like pure speculation not proved by your data

Reply:We agreed with your comment. Therefore, we deleted them in the abstract.

 

 

AC Cnc and UX Com may deserve a separate article.

Reply: We agreed with your comment.We deleted the content of AC Cnc and UX Com.

 

The text needs to be improved considerably. Examples are too numerous to list.

Eg

L33 “stellar radio theory” : stellar theory in the radio domain. Which radio domain ? Cm, mm

wavelengths ?

Reply:We revised to stellar theory in the radio domain with Cm wavelength. Thank you.

 

L30 : “active spectra” What are they ? What do the authors really want to say ? Spectra of active stars ?

Reply: It is spectra of active stars. We check all the text and revised them in our manuscript.

 

L44 : radio stars haven’t been defined at this point.

 

We added the definiation of radio star as star with continuum radiation at the radio wavelength in the first paragraph of introduction.

 

In Table 1 you list “radio stars” observed in LAMOST, but many haven’t a flux value at 4.8 or 23 GHz.

Reply: For many haven’t flux values at 4.8 or GHz, they have 1.4 or 8.6 GHz. We added a note in the table 1..

 

Table column headers, names of axes and numbers are too tiny.

Reply: We enlarger the headers, names of Axes and numbers.

L49 -L52 mention the sections please

Reply: We added the section in L49-52.

 

3 Spectroscopic analysis

L88 when they have been published, what is the reference ?

 

Reply: The program was published in 2007 from internet address (http://myweb.facstaff.wwu.edu/~coveyk/thehammer.html). We revised them.

\bibitem[Covey et al.(2007)]{2007AJ....134.2398C} Covey, K.~R., Ivezi{\'c}, {\v{Z}}., Schlegel, D., et al.\ 2007, \aj, 134, 2398. doi:10.1086/522052

 

L96: boundary 0 Angstrom ?

 

Reply: I am sorry for our poor English. For OBAFGK stars, we use the criterion of EW 0 Å. If the EW value of the Hα line is above 0 Å and simultaneously larger than the errors, and the value of the height of the Hα line must be three times larger than the standard error, we think the behaviour of Hα line is emission.

 

Reader should not have to read other papers to know the basic of what you did.

How was the correction for radial velocity done?

Reply: We used the published LAMOST radial velocity to revise the spectrum and determine the position of the H alpha line.

 

What if the Halpha line showed multiple components and also absorption?

 

Reply: We the Hammer program to the integration with 10 angstrom regions to obtain the EW. At the same time, we used the Gaussian function to fit the H alpha line. The EW difference between the two methods is the uncertainty of H alpha EW.

 

Does 5 Angstrom contain all the flux ? How were the lines fit ? This is important to estimate if the variability is real.

 

Reply: I am sorry for our poor English. It is not 5 Angstrom, it’s 5 Angstroms on left and right side of the Hα line. The total integration region is 10 angstrom.

For the Hammer program, West et al. (2004,2008) computed the H alpha EWs by integrating over the Hα line region (8 angstrom wide centered on the Hα line). We updated the Hammer program from 8 angstrom to 10 angstrom. If we used the larger region, it will include the neighbor spectral line. At the same time, we used the Gaussian function to fit the H alpha line. The EW difference between the two methods is the uncertainty of H alpha EW.

 

L116: you don’t reduce CR, you eliminate them and usually not only in height, but also in width, and, if you have them, using repeated observations.

 

For the cosmic ray, our collaborator help us to reduce them. For LAMOST medium spectra, there are many repeated observations. We reduced the cosmic ray using the cross judgement method. We plotted all the spectrum of our objects and It is well for the result of reducing comic ray.

 

L125: you don’t normalise by polynomial functions, you fit the continuum by polynomial …

We revised them.

Reply: We revised them. We obtained the continuum spectra of the radio stars by 5- or 6-order polynomial functions fitting and the normalized spectrum after normalization.

 

Figure 3 right: it is not the continuum, it is the normalised spectrum after continuum fitting and normalization

Reply: We revised them.

We obtained the continuum spectra of the radio stars by 5- or 6-order polynomial functions fitting and the normalized spectrum after normalization.

The observed medium-resolution LAMOST spectra (left) and its normalized spectrum.

 

Figure 6: different colours represent the different observations, but it is unclear over which region the FWHM is measured or how the lines are fit.

Reply: We revised them. We updated the Hammer program from 8 angstrom to 10 angstrom. If we used more larger region, it will include the neighbor spectral line. At the same time, we used the Gaussian function to fit the H alpha line. The EW difference between the two methods is the uncertainty of H alpha EW.

 

Section 3.5 should be a separate paper

Reply: We agreed with that. We deleted them.

 

Section 4

Section 4.1 lists possible causes for Halpha variability, but no connection with the author’s

observations and data is mentioned. It is not a proper discussion of the results obtained, just

some general list of possibilities and references.

Reply: We agreed with that. We added some contents （including the data and observations and gave the possible causes. For our observation and data, we gave the possible mechanism, which are listed in the last columns of Tables 1 and 3. The detail are listed in Section 4. For LAMOST medium spectral survey has just started for only several years and the data of each object is not enough. I am sorry for that we don’t gave the complex and detailed theoretical mechanism at present. We needed more data to solve in the future.

Thank you.

 

4.2

What is the horizontal axis in Figure 12? Serial number of declination? The red dots in the figure are pointless as they can be well below the detection limit of FAST, hence Figure 12 makes no sense.

 

Reply: I am sorry for our poor English. The horizontal axis is the Serial number according to the size of declination of radio stars. The red dots in the figure represent the radio stars above the detection limit of FAST (the red line). For the green points, it the possible maximum value are above the detection limit of FAST. We beg you to let us retain the Figure 12. It interesting for us to see the information which radio star will be detected and check by FAST telescope. Thank you. We revised them.

 For the red dots in the Figure 9, they are above the detection limit of FAST and it is easy to detect by FAST. For the green points, it the possible maximum value are above the detection limit of FAST and we need FAST to further validation checks.

 

Summary repeats yet again section 4.

Section 4 can be omitted and replaced by the summary.

Reply: We agreed with that. We deleted the section 5.

 

Reply: We are very sincerely grateful to you for giving us the perfect comment to revise them. Thank you for your hard work.

We are sorry for our poor English writing. Now we used an English language editing service of Editage by CACTUS (https://www.editage.com/ It is a brand of Cactus Communications, offers professional English language editing and publication support services to authors engaged in over 500 areas of research) to revise our paper this time using blackbody words. Thank you.

Best Wishes

Liyun Zhang

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

In the manuscript "Physical properties of radio stars based on LAMOST spectral survey and FAST telescope" by Liyun Zhang et al., authors studied the Hα behavior of radio stars, using Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Low and medium-resolution spectroscopic surveys,  and discussed the properties of short and long-term scales variability. They also considered the radio stars in the observation region of Five-Hundred-Meter Aperture Spherical Radio Telescope (FAST) The study is original and results are very useful. The abstract and introduction are informative and the method is well described. The obtained results are important and interesting. My objection is very bad English. After extensive corrections
of English the paper can be published.Below are listed principal errors.
 

l 22 Cvn --> CVn
l 27-28 used...make ? Concord of tenses is not good
l 30 project --> projects
l 44 radios stars --> radio starsa
l 46-48 It is ... radio stars  should be reformulated
l 51 describe ... determined? Concord of tenses
l 69 effect temperature --> effective temperature
l 89 these indicates --> these indicators
l 115-116 ray have been --> rays have been
l 117-118 there is cosmic ray --> there are cosmic rays
l 126 ray --> rays
l 189 These phenomenon --> This phenomenon
l 194 minimum --> minimums (or minima)
l 235 activity --> activity of
l 236 Phenomenon --> phenomena
l 241 show --> shows
l 243 numerous object --> numerous objects
l 271 We shows --> We show
l 202 duing --> during
l 210-212 Liu...activity - reformulate

Author Response

In the manuscript "Physical properties of radio stars based on LAMOST spectral survey and FAST telescope" by Liyun Zhang et al., authors studied the Hα behavior of radio stars, using Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Low and medium-resolution spectroscopic surveys, and discussed the properties of short and long-term scales variability. They also considered the radio stars in the observation region of Five-Hundred-Meter Aperture Spherical Radio Telescope (FAST). The study is original and results are very useful. The abstract and introduction are informative and the method is well described. The obtained results are important and interesting. My objection is very bad English. After extensive corrections of English the paper can be published. Below are listed principal errors.
Reply:

Reply: Thank you for your perfect comments and suggestions on our manuscript again. We agreed with all your comments. We revised all of them. Here we send you our revised form of our manuscript again.
l 22 Cvn --> CVn

Reply: We revised them and checked all our text.
l 27-28 used...make? Concord of tenses is not good

Reply: We revised them. Used and made are consistent with each other.
l 30 project --> projects

Reply: We revised them.
l 44 radios stars --> radio stars

Reply: We revised them.
l 46-48 It is ... radio stars should be reformulated

Reply: We combined the two sentences to one sentence. It is also important to detect the relationship between the optical and radio wavelengths on nearby radio stars in the future.
l 51 describe ... determined? Concord of tenses

Reply: We revised determined to determine. Now it is consistent with each other
l 69 effect temperature --> effective temperature

Reply: We revised them.
l 89 these indicates --> these indicators

Reply: We revised them.
l 115-116 ray have been --> rays have been

Reply: We revised them.
l 117-118 there is cosmic ray --> there are cosmic rays

Reply: We revised them.
l 126 ray --> rays

Reply: We revised them.
l 189 These phenomenon --> This phenomenon

Reply: We revised them.
l 194 minimum --> minimums (or minima)

Reply: We revised them.
l 235 activity --> activity of

Reply: We revised them.
l 236 Phenomenon --> phenomena

Reply: We revised them.
l 241 show --> shows

Reply: We revised them.
l 243 numerous object --> numerous objects

Reply: We revised them.
l 271 We shows --> We show

Reply: We revised them.
l 202 duing --> during

Reply: We revised them.
l 210-212 Liu...activity – reformulate

Reply: We revised them. Liu et al. (1997) found the H${\alpha}$ line of UX Com show a filled-in absorption caused by chromospheric activity.

We are sorry for our poor English writing. Now we used an English language editing service of Editage by CACTUS (https://www.editage.com/ It is a brand of Cactus Communications, offers professional English language editing and publication support services to authors engaged in over 500 areas of research) to revise our paper this time using blackbody words. We also deleted some contents according to the comment of Review1. Thank you.

Best Wishes

Liyun Zhang

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear authors,

Thank you for taking into account my suggestions for improvement. The description of the methodology and presentation of results have improved considerably, however it still needs significant editing of the English language. For instance in the Abstract l12-13 -> minimal detectable radio flux; l 18 radio emission; l32 cm wavelengths etc. 

The accuracy can still be improved.

eg the title : The objects are not observed by the FAST telescope as yet, hence the title is not correct: the physical properties are not based on the FAST telescope.

Why are the radio flux values at 1.4 and 8.6 GHz not listed in the table. It seems useless to list only non-existent measurements and upper limits. Please add existing measurements at 1.4 and 8.6 GHz. Table 3 mentions HAlpha, without mentioning the quantity or unit listed. l132 normalised spectra after normalisation. l145: you need more spectra, but if the emission is not due to a binary, "orbital phase" makes no sense. Based on the data presented, the cause of the HAlpha emission cannot be ascertained and is not proven in the paper.  Hence if you mention possible causes, eg disk in the table, based on yours and especially other data, mention the reference in Table 1 and 3.  There may be multiple variation mechanisms ... Moreover it is one title for 3 columns, which is not accurate nor well determined. One has to be able to understand the table precisely without having to search nor read the paper (Variability: long term, short term, possible origin ? )

I have no time to go through it in detail at the moment. I have no time for a detailed report, but I list some examples for improvement below. Please, pay attention to the captions of the tables and figures, in order for them to be understood without reading the article.

Best regards

Author Response

Dear authors,

Thank you for taking into account my suggestions for improvement. The description of the methodology and presentation of results have improved considerably, however it still needs significant editing of the English language. For instance in the Abstract 

l12-13 -> minimal detectable radio flux

; 

l 18 radio emission;

l32 cm wavelengths etc. 

Reply: Thank you for your perfect comments and suggestions on our manuscript again. We agreed with all your comments. We revised all of them. Here we send you our revised form of our manuscript again.

 

The accuracy can still be improved.

eg the title : The objects are not observed by the FAST telescope as yet, hence the title is not correct: the physical properties are not based on the FAST telescope.
Reply: We deleted the FAST telescope from the title. We revised it to “Physical properties of radio stars based on LAMOST spectral survey”.

Why are the radio flux values at 1.4 and 8.6 GHz not listed in the table. It seems useless to list only nonxistent measurements and upper limits. Please add existing measurements at 1.4 and 8.6 GHz. 

Reply: The intensities of different wavelengths are from the published catalogue of radio stars (2015yCat.8099....0W) in June, 2015. Because the values of radio stars are not observed by us, and it is easy to download the radio intensity in all the radio wavelengths from the ads internet (https://cdsarc.cds.unistra.fr/viz-bin/cat/VIII/99#/browse). Therefore we only listed radio star with the most highest number in different wavelengths. We added a note at the bottom of our Table: We only listed the radio intensity of 4.8 and 23 Ghz and tell the reader how to find and download all the intensity of radio stars in all the radio wavelengths. The definition of the radio stars was that detected at least once and those with upper limits by the authors of the radio catalogue (Wendker et al. 1995, 2015). It is normal that the authors gave the upper limits of radio stars for Radio astronomy. We are sorry for that we did not delete the upper limits. We are sorry for that.

 

Table 3 mentions HAlpha, without mentioning the quantity or unit listed.

Reply: We added the unit of the H alpha. Thank you.

 

 l132 normalised spectra after normalisation. 

Reply: We revised them.

 

l145: you need more spectra, but if the emission is not due to a binary, "orbital phase" makes no sense. Based on the data presented, the cause of the HAlpha emission cannot be ascertained and is not proven in the paper. Hence if you mention possible causes, eg disk in the table, based on yours and especially other data, mention the reference in Table 1 and 3.  There may be multiple variation mechanisms ... 

 

Reply: We deleted the sentence “We need more spectra in completely different orbital phases to simulate the detailed structures of the disk or active region.”. We gave the main references in Tables 1 and 3 and added the note that There may be multiple variation mechanisms. We are sorry for that based on the data presented, the cause of the H alpha emission cannot be ascertained and is not proven in the paper.

 

 

Moreover it is one title for 3 columns, which is not accurate nor well determined. One has to be able to understand the table precisely without having to search nor read the paper (Variability: long term, short term, possible origin ? )
Reply: we revised them.

Table1. Parameters of radio stars observed in LAMOST low resolution spectral survey, and their H${\alpha}$ properties.

Table2 Radio stars with repeated spectra from low resolution LAMOST survey DR7 and their H${\alpha}$ variation in long term scales about several months.

Radio stars with LAMOST medium-resolution spectra and their H${\alpha}$ variations in short term scale about 20 min.

 

I have no time to go through it in detail at the moment. I have no time for a detailed report, but I list some examples for improvement below. Please, pay attention to the captions of the tables and figures, in order for them to be understood without reading the article.

Reply: We revised the captions of the tables and figures again. We are sorry for our poor English writing. Now we used an English language editing service of Editage by CACTUS (https://www.editage.com/ It is a brand of Cactus Communications, offers professional English language editing and publication support services to authors engaged in over 500 areas of research) to revise our paper again. Thank you.

 

 

 

Best Wishes

LIyun Zhang

 

 

 

 

 

Author Response File: Author Response.pdf