TCP J15244460-6059200

[Tom Love]

A nova found by Andrew Pearce from Perth, Australia. There has been follow up from the SOAR telescope, and I have managed to get an Alpy spectrum, with identifications from Peter Velez.

J2000.0 coordinates are: RA 15 24 47.6, Dec -60 59 47.3

http://www.cbat.eps.harvard.edu/unconf/ ... 59200.html

https://www.astronomerstelegram.org/?read=15473

ASAS-SN lightcurve: https://asas-sn.osu.edu/sky-patrol/coor ... 3c6047d476

[Robin Leadbeater]

I have just seen this curious object reported on vsnet-alert. The progenitor appears to be only about 3 magnitudes fainter. It is a very packed field though so I suspect it might turn out to be a superimposition. We will see as it fades though if the spectrum becomes a mix of nova and another star.

Cheers
Robin

[Hamish Barker]

tom managed to get a second spectrum the next day, and Peter Velez got a blue/UV one with his UVEX on the same day as Tom's first observation. I managed a not so great one on the first night, data still to be reduced, as I was in the middle of a focuser upgrade. I think they will all be sent to Francois for the ARAS database shortly.

[Tom Love]

It's now officially FQ Circini, which is a lot easier to type into your object name field...

http://www.cbat.eps.harvard.edu/iau/cbe ... 005138.txt

[Tom Love]

I managed another on FQ Cir - it's about 3+ magnitudes fainter, so noisier even with a 4 hour exposure. There aren't obvious signs of narrow absorption lines from a 'normal' shadowing star over the precursor. The continuum has shifted to the blue a lot, and there is a new very wide feature at around 4600-4700 angstroms. The Balmer lines are showing very clear double peaks (some kind of disk I presume?).

PlotSpectra is showing New Zealand times. Subtract 0.5 for UT.

The instrumental setup, response star and reduction procedure are the same for both spectra - the only difference is in exposure time. I'm really not sure what to make of this. It would be good to have confirmation that I haven't messed up the observation somehow...

[Tom Love]

Though Hamish has just pointed out that a shadowing B star with big H absorption lines would create double peaks as seen here. And I think it might also explain the shift to the blue in the continuum.

[Robin Leadbeater]

Patrick Schmeer dug out some data on the potential progenitor/superimposed star on vsnet-alert

Quote

"The likely progenitor is the Gaia DR3 source 5875610751015084544
(Gmag. 13.75, BP-RP= 0.73, Teff ~22500 K, parallax 0.11 ± 0.02 mas,
distance 6.5 ± 0.8 kpc).
SMSS data: gPSF= 13.98, rPSF= 13.70, iPSF= 13.74
APASS data: V= 13.88, B= 14.35, g'= 14.08, r'= 13.70, i'= 13.65"

So based on this a reddened hot star. (~B0 from Teff~22500 which should have B-V ~-0.3 so E(B-V) ~0.8 or ~2.4 mag extinction

The apparent V magnitude corrected for extinction of 13.88-2.4 = 11.5 at 6.5kpc gives an absolute magnitude of ~-2.6 which is underluminous even for a main sequence star. Not sure how well Gaia estimates Teff though. I have seen some big errors when actually taking spectra of some of these.

Best guess could perhaps be say B2v ?

Robin

[Tom Love]

I think that would fit as an explanation of the Balmer line twin peaks and the continuum slope shift (assuming the nova was further away and even more reddened), if the potential progenitor spectrum was actually unrelated and blended with the nova spectrum. Though I'm still a bit unclear on the 4600-4700 Angstrom feature and what it might mean.

[Robin Leadbeater]

Though I'm still a bit unclear on the 4600-4700 Angstrom feature and what it might mean.

He II N II blend ? (There are other broad NII lines in the spectrum I think)

Robin

[Tom Love]

Yes, perhaps something like that, which is consistent with the feature emerging as the continuum drops.