Talk:V491 Car

Quick-look comments

 * The NW component do have both H and K in emission, contrary to the first assessment at the telescope.
 * The SE component is a single star. Looks like a normal K5 dwarf. But!!! it shows very narrow Na D in emission, somewhat offset from the center of the stellar lines. These lines are not coming from the stellar atmosphere (offset) and not from the corona/chromosphere (too narrow). The only similar thing I've ever seen is spectra of Io, where these very narrow lines come from the active volcanism of Io.  Next thought... a tidally stressed planet with heavy volcanism... comments welcome!  We shold observe this one again.
 * (added by Tdall 11:13, 12 April 2006 (CLT)) Beware, beware! The spectra are not background corrected, so the emission could be sky - we have to investigate... I discovered that I made a grave mistake when making the OBs... using objA instead of objAB, which means that the spectra are not background subtracted, which could be disastrous for twilight spectra :-( I have corrected the OBs including for V491 Car. But still, there is no emission in the NW comp. Hm.

Tdall 15:24, 7 April 2006 (CLT)


 * Two things I don't understand though about the SE component, that you will explain to me. 1. Why it is offset? Because of "orbital" motion? If so a second spectrum is mandatory. 2. I don't remember. :-) It's midnight. I'll come back tomorrow. A very interesting star indeed! So good for VSOP future! -- cedric 17:53, 7 April 2006 (CLT)

Why is it offset? Beats me! The narrow emission is aprx at the rest wavelength of NaD, but it's not from the Earth environment, since we don't see it in the NW comp. The second spectrum taken last night shows reveals a fainter stellar companion! - so both components are SB2's. The narrow Na emission may have moved slightly, but it will have to be verified by a third spectrum. The source of the emission would need to be relatively cool (sharp lines) but localized close to the star (we don't see it in NW comp.) Tdall 17:08, 8 April 2006 (CLT)


 * The emission is roughly at the 0 velocity, right, and the whole broad Na line at ~+11 km/s. Could you make available all the 1D spectra in this page, Thomas? I cannot access to the vsop machine (??). To make sure this emission is physically associated with the system, we must check that it moves in one way or another, no? Even slightly! You said tha main star is a K5. Could the companion be a compact object? Well, I guess very narrow lines like that (-0.16 / - 0.09 A) can't be easily associated with accretion disks... Linda? Yes, we must make sure it moves! Thomas, put the spectra, I'll make a cross-corr (if no one did one already). -- cedric 10:42, 10 April 2006 (CLT)

Spectra are there now, including the CCF's. Third epoch scheduled for tonight (2006-04-10). The sharp emission does seem to move slightly, and given the precision of HARPS, I'll take it to be real. But let's see after third epoch... I don't think accretion can produce such narrow lines. If it is local to the system, then it's associated with the heavier component and not with the companion that came into sight at epoch 2. How about the rest of the team? - any comments anyone??? (roaring hollow echoes.....) Tdall 11:51, 10 April 2006 (CLT)


 * I surveyed other targets taken with the objA templates in twilight, and they show the same narrow Na D peaks. I surveyed the 'B' (sky) spectra of a few targets taken with objAB template, and they show these emission lines as well. Conclusion: The sharp Na D lines are from the sky! -- Tdall 20:40, 4 June 2006 (CLT)


 * Of course... :-( -- C édric [[Image:kmail.png|16px]]T alk  02:15, 5 June 2006 (CLT)

Radial-Velocities from Gaussian fit + Cross-Correlation
Hi There. Not sure what can be concluded, but below I put the RVs, I computed. First, the RVs by simple Gaussi fit (inside IRAF) of the large broad Na absorption and narrow emission lines. Line "1" is the one at 5889.950, while line "2" is the one at 5895.924 A.

V491_Car_SE-VSOP-spectrum      5890.15 5889.94 5896.22 5895.91  10.18  50.39  15.05   -0.71 V491_Car_SE-VSOP-spectrum-2    5890.13 5889.92 5896.19 5895.90   9.16  49.37  13.52   -1.22 V491_Car_SE-VSOP-spectrum-3    5890.18 5889.91 5896.22 5895.88  11.71  48.86  15.05   -2.23
 * 1) spec                          abs1    emm1    abs2    emm2    rva1   rve1   rva2    rve2

The ones from cross-corr between 5400 and 5800 A. Reference spectrum is V491_Car_SE-VSOP-spectrum. So it encompasses only absorption lines supposedly coming only from the stellar object (as far as we don't know what is the emission-line component, if any).

V491_Car_SE-VSOP-spectrum ->V491_Car_SE-VSOP-spectrum     0.000 +- 0.000 V491_Car_SE-VSOP-spectrum-2->V491_Car_SE-VSOP-spectrum   -0.546 +- 0.258 V491_Car_SE-VSOP-spectrum-3->V491_Car_SE-VSOP-spectrum   -0.121 +- 0.080

Are these variations real? It seems so. Emission does not seem to vary with absorption. However, 1st line does not seem to show same variations as line 2, both for abs and emm. ?? -- cedric 08:38, 12 April 2006 (CLT)


 * Interesting. So this means that the absorption lines of the strongest component are indeed moving. One thing Dominique pointed out: The velocity of the companion visible in spectra 2 and 3 corresponds roughly to the barycentric RV correction, i.e. it could be the solar spectrum. In fact, I discovered that I made a grave mistake when making the OBs... using objA instead of objAB, which means that the spectra are not background subtracted, which could be disastrous for twilight spectra :-(  I have corrected the OBs including for V491 Car.  Still though, the NW component was also taken in twilight.


 * What?! Background is not subtracted?! ... Yes, we must be very careful. Hand-made reduction is possible? Could emission on top of Na lines come from the sky?... -- cedric 05:50, 13 April 2006 (CLT)


 * No way to redo the reduction: there is no background spectrum recorded - the sky fiber was dark. My mistake - now corrected. Na emission from the sky, and only during twilight... it doesn't sound reasonable to me, but there's only one way to check that... blank sky! And the star must be re-observed with the AB template (already in the queue).  Another matter is that the 'companion' in the CCF could come from the twilight sky solar spectrum superimposed on the stellar spectrum. But as I said, this is another matter.


 * OK. Wait and see. Was too good to be real. I hope you have corrected all OBs... :-) -- cedric 15:28, 17 April 2006 (CLT)


 * All OB's corrected of course. And I confirm (see above) that the emission comes from the sky. -- Tdall 20:40, 4 June 2006 (CLT)

Since the speed of the faint component has bee confirmed by Gaspare and Ivo that it is not -770 km/s, I archive the infos found on this page here. -- C édric T alk  13:28, 8 June 2006 (CLT)

Original quick-look subsection before spliting

 * NW comp: K5V+K? SB2, systemic RV~15km/s. CaII emission mostly from primary. Slow rotation. No Li. See [[Media:V491_Car_NW-VSOP-plot-CaII.ps.gz|plot of CaII region]].


 * SE comp: K3V. RV=12.1km/s and 12.6km/s on 2006-04-04 and 2006-04-07 respectively. On first date appears single, on the last date it is apparently a SB2. Strong narrow NaD emission on both dates... - both 'extra' component and Na D are due to the sky background! See [[Media:V491_Car_SE-VSOP-plot-NaD.ps.gz|PS-plot]]. Also weak and broad CaII emission. No Li. Still, the change in RV suggests SB.


 * Faint comp: F8 type. RV=-13km/s (is not -700km/s... see dedicated discussion page).


 * 1D fits spectra and CCFs:
 * Spectra:
 * [[Media:V491_Car_NW-VSOP-spectrum.fits.gz|Spectrum NW component]],
 * [[Media:V491_Car_SE-VSOP-spectrum.fits.gz|2006-04-04 spectrum SE component]],
 * [[Media:V491_Car_SE-VSOP-spectrum-2.fits.gz|2006-04-07 spectrum SE component]],
 * [[Media:V491_Car_SE-VSOP-spectrum-3.fits.gz|2006-04-10 spectrum SE component]],
 * [[Media:V491_Car_faint_gr3-VSOP-spectrum.fits.gz|2006-04-28 spectrum faint comp., Grism#3]],
 * [[Media:V491_Car_faint_gr16-VSOP-spectrum.fits.gz|2006-04-28 spectrum faint comp., Grism#16]],
 * CCF's:
 * [[Media:V491_Car_NW-VSOP-CCF.fits.gz|CCF NW component]],
 * [[Media:V491_Car_SE-VSOP-CCF.fits.gz|2006-04-04 CCF SE component]],
 * [[Media:V491_Car_SE-VSOP-CCF-2.fits.gz|2006-04-07 CCF SE component]]
 * [[Media:V491_Car_SE-VSOP-CCF-3.fits.gz|2006-04-10 CCF SE component]]