Subject: Re: suggestions for beta Cru paper From: David Cohen Date: Thu, 06 Sep 2007 15:13:59 -0400 To: "Gagne, Marc" CC: "David H. Cohen" , Michael Kuhn , Eric Jensen Marc, Some responses to the specific points you raised in this email, to go along with the latest update to the manuscript and the to-do list, which I will send to all of you in a minute. David > ii) I'll work on a plot showing the MEG spectra with ISIS model later today. > OK, I still think this would be a nice addition to the paper, but it's not crucial. Anything new with Heunemoerder and the f/i patch for APEC? > iii) In the current fits, the redshift is fixed at 1E-04 (+30 km/s). I'll set it to zero, see if the line wavelngths are fine. If not, I'll find an error on the 30 km/s. I don't know the value of the systematic error in the wavelength calibration. > OK; I found it out, and it's 100 km/s (conservatively; probably it's really a bit less than this; See Herman Marshall's 2004 SPIE paper, if you're curious; Also Bish has a presentation on the CXC website from a talk he gave at a calibration workshop). If you still want to do this, that's fine, but not necessary, I think. > > iv) I'll have a look at the secondary spectrum. I don't think it's overkill. We might as well make the most of the observation. > Again, worth doing if it's not too much trouble. Let me know if you pursue it. > v) I'm a little concerned that many of the action items fall to Mike. I could, for example, make some of the time variability plots. > Mike, what do you think? Making a binned light curve plot for the companion is the main remaining task in this category, I think. > > Suggestions: > > i) Table 1: beta Cru's stellar parameters appear to have been updated in Hubrig et al. (2006). Aerts is an author on this paper too. I agree that we should use the measured size of the star to constrain the other parameters. It looks like the parameters in Table 1 of Hubrig's paper are based on stellar atmosphere modeling of the Geneva photometry. So, maybe the spectroscopic modeling of Aerts (1998) is better. A note then in section 2 on the Hubrig values might be worthwhile. Where did you get the LC IV designation? Conny Aerts lists B0.5 III and the larger radius is consistent with a giant. > OK; Marc and Eric, I think we should talk about this in person. I have extensive notes on how I came up with the values in Table 1; I think it would be worthwhile to look at those and compare them to the Hubrig paper. Maybe the next time you're in the department, Marc. > > > ii) Introduction: I think some mention of magnetic field detections on beta Cephei and SPB stars may be needed. Note the null detection of B_l on beta Cru (Hubrig et al. 2006). The results section could compare the pulsation periods and amplitudes and X-ray and magnetic properties of beta Cru to other beta Cephei stars. > > beta Cephei stars > > Star ROSAT PSPC count rate Notes > beta Cru 0.586 0.765 c/s corrected for companion, no field > beta Cep 0.151 field > gamma Peg ? RASS upper limit, no pointed observations, field > xi1 CMa 0.066, 0.099, 0.103 field > V2052 Oph ? RASS upper limit, no pointed observations, field > nu Eri 0.0128 no field > beta CMa 0.240, 0.236 no field > V836 Cen ? RASS upper limit, no pointed observations, no field > theta Oph ? RASS upper limit, no pointed observations, no field > kappa Sco 0.062 no field > > beta Cru appears to resemble only beta CMa in most of its properties. > We should also talk about this... but I think it ultimately isn't that relevant. > > iii) I notice you avoid $\beta$~Cephei. Is it conventional to spell out beta? > I don't know. I'll keep my eyes open as I look over Aerts's paper and others. What do you think? > > iv) Add key word -- stars: oscillation > OK. > > v) section 4.1, footnote 2: you mention the ROSAT count rate, but not its value. Note: when I use PIMMS to estimate PSPC count rates for both stars based on the spectral parameters in sections , I get: 0.59 c/s in PSPCB for beta Cru A and 0.08 c/s for the companion for a total PSPC count rate of 0.67 c/s, pretty close to the RASS rate of the combined system. > Alright; I've eliminated that footnote. > > vi) We can expand on Table 6 obviously. We could make a similar table for the companion. > I'm sorry, which table? Table 5 has the f/i information. I don't think it's worth doing that for the companion (the results are in the text, sec. 5.1). A table with the thermal model fit parameter values also is overkill, I think. > > vii) Should we suggest a name for the companion? In fact, we need to give names to all the objects in Table 2. HD 111123 (beta Cru A) is the B0.5 III star. Simbad lists the visual binary at ~45" as HD 111123B, i.e., the B component. Does that make the B2 V SB1 companion beta Cru C or beta Cru A2? I prefer beta Cru A2. I don't think Aerts suggests a name for the spectroscopic companion. > OK, Eric is on it... > > > There are numerous visual and infrared sources beyond 60", including the second Washington Double Star companion at 368". These stars should not have names associated with beta Cru. Since the X-ray source at 4" is a visual companion, wouldn't beta Cru C be most correct? If it turn outs later to be > But we can't just reuse names (like beta Cru B), can we? > > itself a spectroscopic binary, its components would be beta Cru C1, beta Cru C2, etc... This is how we've handled it in Orion. The alternative is to give it a name like BCRUX (like Acrux), HD 111123X or a telephone number name like J124743.8-592141. > Thanks for all this, Marc.