I will do it tonight again. clear skies. In two hours or so.
This is an example of how objects in the south can be a problem because of the paucity of observers! Iâve notified the spectroscopy section of my local astronomy association here in Brisbane, Australia and asked for spectra once the current cloud clears.
Roy
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Ive got a run yesterday and today of BVRI images every 6 seconds each. The spectrum continues flat without any substantial mod. This is a curious target. Also it is curious that the community is basically deaf on this one. It seems a normal A class star 
Is it possible that this star is one that has just been âbornâ? I.E. just started fusing hydrogen? If so (or not), would this be the first time this has been observed?
What you mentioned reminded me of the FUOR (FU Orionis) outbursts, when a YSO brightens by several magnitudes and stays bright for years, displaying an F supergiant spectrum. That would be an absorption spectrum. But this object was blue not a T Tauri star, and FUORs brighten by several magnitudes but not 13 to 17 magnitudesâŚ
But at this point I think we shouldnât rule out anything.
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I think progenitor was misidentified. Iâve made a more precise astrometry and position is 10 25 13.92 -53 31 19.3 . Progenitor is a A class star with no variability detected in Gaia. ID is Gaia DR3 5357126628308746112. This is more likely a microlensing event and not a nova.
Hi Paulo,
that is the current ID of the star. How do you know it was an A-type star? There are no spectra in the Gaia DR3 catalog.
The star you mentioned was blue and strongly variable, either by eclipses or outbursts.
The light curve is not the light curve of a microlensing event either.
Cheers,
Sebastian
Hi Sebastian,
Data in GAIA shows BP â RP = +0.309 mag with indicates, when you consider reddening in Vela region, to an A class star. There is no variability also in GAIA data for this star. It has not detected in the time run of the survey. Where did you find this variability in GAIA data ? For me it seems that the spectrum of the star seems to be the same all time. This would mean microlensing or dust that is disappearing from the line of sight. I agree that these would be severe events of this kind. Lets see how the star evolves and if another person can get better spectra. We can ever be wrong in something. I was managing 4 scopes at once. 
. I´ve warned ASASSN and they are professionals that will have a much better analysis of the case than I can do. It ever can be a Nova that waits a bit to show emission, Who knows ? Tomorrow I will check it again.
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Hi Paulo,
There is no parallax information in Gaia, so there is no constrain on the starâs luminosity.
I had added all these findings and photometric information in the VSX entry of the star where the ID was established already when the star was added.
Read the remark here.
I didnât say that Gaia detected variability. Gaia detected the star in the bright state, this is typical of variable stars only detected a few times and thus not getting proper motion data or parallaxes. The faint states were detected once by VPHAS+ (some detections at 18+ and one at 21.4 i) and in two images from DECaPS around mag. 22 g and even fainter in r. I had already posted the DECaPS image in this thread.
You now see an A-type spectrum, you canât extrapolate that to the progenitor, because we donât have data. E.g. FUORS are F-type in outburst but T Tauri stars at minimum.
A white dwarf might be responsible for the white color at minimum.
The microlensing event hyphotesis doesnât seem to be supported by the available data. The relatively rapid brightening and extended maximum (instead of a sharp maximum) are not typical of a microlensing event.
I think this is still a mistery to solve.
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I like mysteries. Lets see what happens tomorrow. Time to sleep here. Good night.
âŚwell as end of extremely long eclipse?
Several ATELs now
|17254|Bright nova V572 Vel Has Orbital Period of 0.12317997 Âą 0.00000010 days|Bradley E. Schaefer
28 Jun 2025; 06:48 UT|
| â | â |
|17253|OGLE Pre-Eruption Observations of V572 Velorum Reveal Dwarf Nova Outbursts|K. Ulaczyk, P. Mroz, A. Udalski
28 Jun 2025; 06:25 UT|
|17252|Fermi-LAT Gamma-ray Observations of the Probable Nova V572 Velorum|
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This seems to confirm a Nova. Case closed.
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V572 Vel (the possible nova in Vel) appears to be a SUUMa-type dwarf nova. ATel #17523 (Ulaczyk et al.) (https://www.astronomerstelegram.org/?read=17253) reports archived OGLE observations show previous dwarf novae outbursts since 2017, with both regular and superoutbursts.
Coverage throughout this superoutburst and for several weeks after return to quiescence are strongly encouraged.
Good observing,
Elizabeth Waagen, AAVSO HQ
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New info from ATel #17256 https://www.astronomerstelegram.org/?read=17256 (Steve Shore et al.) âOptical spectroscopy of V572 Vel: Not obviously a classical novaâ
Spectra are provided at the following URL:
https://aras-database.github.io/database/pnvvel2025.html
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Yesterday it was cloudy here. My take is that is a principal A class star with a binary nova that is being occulted, even if an A class is what is expected from a nova at this point. . Ive not yet detected emission or P-cyg. Lets see tonight. ChatGPT says that a WD classical nova with an unusually dense equatorial torus is still the simplest, most self-consistent explanation.
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The DECaPS image is impressive! Nothing like using a 4-m telescope to survey the sky I always say!
Jim (DEY)
Perhaps a luminous red nova (LRNe). Searching for the next Galactic Luminous red nova - Astrophysics Data System
Jim (DEY)
In a few hours I will have a new spectrum. Lets see what happens. If it continues to be absorption then we have something distinct here.
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