Dear Axel, they sent me a report today. I read it, there are some good comments about our paper. We have 6 months to make changes on it. I will have the state exam on 25. August, so I little busy for now. We could check it and make changes and maybe have a zoom call after my state exam. I hope it is ok for you. I wish you all the best. Best regards, Patrik ---------- Forwarded message --------- From: Astronomy & Astrophysics Date: Thu, Aug 13, 2020, 02:17 Subject: AA/2020/38564: referee report To: 13/08/2020 Dr Patrik Jakab patrik.jakab94@gmail.com Our Ref. : AA/2020/38564 Dear Dr Jakab, Your manuscript entitled : "The effect of a dynamo-generated field on the Parker wind" was reviewed by a referee who does not recommend publication at this stage. The referee is willing to read a new version of your work if the manuscript is revised to address the points raised in the enclosed report. When you resubmit your paper, please take all of the referee's comments and suggestions into account in the revision and load the new version (in referee format and in printer format) on our Manuscript Management System located at https://mms-aanda.obspm.fr/is/aa/resubmit_a_paper.php. Your author ID number is 32789. - In your cover letter, please indicate precisely all the changes made in the revised version. Please also include your detailed responses keyed to the items in the report. - Mark all the changes clearly (using boldface or latexdiff) in your manuscript. The deadline for the submission of your revised version is six months. With best regards, steve Steven N. Shore A&A Editor ------------------- Referee report Summary: In this paper, the authors use a novel model which combines a mean-field dynamo with a self-consistent (parker) stellar wind. Unlike most previous works, the authors use a single code to accomplish this rather than combining existing codes to compute the dynamo and stellar wind solutions independently. This allows the magnetic dynamo and stellar wind to dynamically interact, producing time-varying solutions. The paper reads as a benchmarking of their model, clearly explaining the physics encapsulated by it, and then applying it to a few different parameter regimes. First a solar-like case, then two rapidly rotating cases. This is an important piece of work as it sheds light on previously uncoupled systems, detailing a constructive way to bridge dynamo and wind physics. The paper is written well, however some of the figures are difficult to digest (which distracts from the results, see comments below), and in some respects the element that makes this work unique is not explored fully. This being the interactions between the dynamo and stellar wind. The impact of this paper would be greatly increased by the inclusion of a more detailed assessment of how the stellar wind influences the dynamo in the different rotation regimes. It is especially important to understand the “benefits” of modelling them in a coupled manner, as doing so constrains the parameter space in which the authors' model can be run (and remain numerically stable), whereas uncoupled models are able to use dimensionless parameters (diffusivity, viscosity) that better approximate both the dynamo and the stellar wind. There are some issues that the authors need to address before I can recommend this for publication. Below I list some major comments which must be addressed, and a few minor comments which would improve the general quality of the paper. Major Comments: In the introduction, the authors mention that the photosphere, chromosphere, etc, are ignored in their model. The authors should therefore make it clear how this assumption influences their results. How do the authors see this boundary being better approximated in future models? i.e. how can the effects of flux emergence be incorporated. The authors rightly mention the work of Perri et al. (2018) in the introduction (another example of similar work is Pinto et al. 2011), but more recently this group have been working on a coupled code similar to that presented in this paper. It would be interesting to briefly compare these independent codes. Perri et al uses the PLUTO MHD code, in a similar way to the author’s model, see https://arxiv.org/pdf/1912.01271.pdf . The figure captions are generally inadequate to describe the figure contents. Though the text describes the figures in a concise manner, often there are multiple lines in each panel which are not described and this causes confusion for the reader. Axis labels have been left off in Figures 2, 3, 5, 10, 11, and 12 which should be included to show the normalisation of the axes scale (either by the magnetic field strength, or length scale). In Figure 5, a few panels show open magnetic field in the stellar wind to be disconnected from the surface (these appears as v-like structures in the stellar wind). Are these physically reasonable, or consequences of the numerical/chosen diffusivities in the model? In either case, these are significant features in the authors’ model and should be discussed appropriately. Have the authors validated their model conserves other quantities like the open magnetic flux in the wind, and the angular momentum-loss rate, in the same way that they have evaluated the mass-loss rate, i.e. on concentric radial shells? In Section 3.4, the meaning of paragraph 4 (beginning “The kinetic..”) is not very clear and should be clarified. Additionally, the authors may wish to consider reorganising this section since a number of the paragraphs are rather short. Perhaps the energy balance in the wind is better discussed after the kinetic and magnetic luminosities are introduced? In Figure 8, the y-labels are denoted L_K and L_M, whereas I think the quantities plotted are E_K and E_M. Though which is red/blue is also not obvious. What is the energy source for the increasing kinetic energy of the wind with radial distance, given the wind is isothermal, and the magnetic energy is ~20 times smaller than the kinetic energy? This should be clearly detailed within Section 3.4. In Section 3.5, the angular momentum flux in the kinetic term is said to dominate over the magnetic term, with Figure 9 showing this to be true for almost all radial distances. However, for a Weber & Davis (1967) stellar wind, with which this model should be in accord, the angular momentum in the kinetic and magnetic term varies with radial distance as stresses in the magnetic field transfer angular momentum into the kinetic term. Why is this not the case in the authors’ model? Perhaps the magnetic field is so weak that it lies in an extreme part of the parameter space, and so this effect is difficult to distinguish? Plotting the angular momentum-loss rate versus radial distance (i.e. on concentric radial shell) for the kinetic, magnetic, turbulent terms and their total, may shed light on this. The authors note that the kinetic angular momentum flux varies from positive to negative, which can be seen in Figure 9. This is highly unusual for this kind of Parker wind model, implying that the wind is rotating opposite to the direction of stellar rotation in these open field regions. Could the authors please explain how this is possible, perhaps there is a need to investigate the azimuthal flow of the wind at the surface boundary (R). I would encourage the authors to consider adding some material which relates to the dynamo-wind coupling, and how it changes with increasing rotation etc. This could be included at the end of Section 3. The abstract and conclusion should also reflect this as it is an exciting and new aspect to this kind of research. Minor Comments: In the conclusion of the abstract, the authors’ remarks are quite generic i.e. commenting on results which are, in general, expected based on previous steady-state and uncoupled wind models. For example, variable angular momentum flux is shown in Perri et al. (2018), and the collimating effect of rapid rotation on the wind outflow in Washimi & Shibata (1993). In my opinion, the abstract would be enhanced if the authors considered what features of their work are novel and modify their conclusions accordingly. The use of r_* and R throughout the paper is a little confusing, the authors could consider changing r_* (which is the sonic/critical point in the wind) to r_c, or something similar. The authors set r_*=1 (the sonic/critical point) though in Figure 3 the transonic surface is actually smaller than 0.5 (shown with a solid line). What causes this change in parameter space? This should be made clear in the text. In equation (26), omega bar has not been defined in J_* (it doesn’t seem to be defined anywhere in the paper, despite being used further in Section 3.5). Additionally, the authors’ method for calculating M dot, and J dot, are not shown in Section 2.5, yet values are quoted for both quantities. I suggest referencing the later Sections that discuss them. In Figure 4, the colorbar is difficult to read and obscures some of the data. Figures 6, 7, and 8 are very busy. Each panel within a figure showing a different time step, and then either many different radial or latitudinal profiles. Again the lack of accompanying detail in the figure captions makes these hard to understand. Additionally, the figures are not discussed within the text to justify their complexity. Therefore, the figures should either be better discussed in the figure caption or main body text, or the content of each panel should be made simpler. For example, why not show the average profile for each time step along with the maximum and minimum variances, or just show fewer radial/latitudinal profiles in each panel. Small text should be avoided, and the line colors and styles should be described adequately in the figure captions. Equation (34) is very similar to the poloidal vorticity-current stream function (\Lambda) which is often used in stellar wind studies (Keppens and Goedbloed 1999, Réville et al 2015, Pantolmos et al. 2017) and has recently been used in studies of the solar wind (Finley et al. 2019). It might be worth connecting this to previous works, in order to increase the impact of this paper. In Section 3.6, “breaking” is used instead of braking. In Figure 10, the angular velocity contours are easily confused with field lines as they are the same color etc as Figures 3 and 5. Perhaps change the color or linestyle of these (to make it clear that they are different between figures)? It would also be interesting to see the field lines and Alfvén surface for the rapidly rotating cases, to compare these with the solar case. When introducing the contours of rotation in Section 3.7, it would be useful to compare the contours for the solar case to the rapidly rotating cases. Perhaps all the 3 models could be shown in Figure 10? In Figures 11 and 12, it looks like there is no B_phi in the grey part of the domain, is this a choice in colorbar or actuality? Why are field lines not shown for the rest of the domain? The x axis of figure 12 has been incorrectly labelled as B_phi. The authors might consider moving Figure 14 to the appendix as it is not discussed enough within the text and is only shown for completeness. The current material within the appendix could be removed as it is not new and does not serve a purpose in the paper.