Waiting for T CrB aka the Blaze star

[Tomatobro]

Still not gone bang as of last night

[IB20]

Blaze star not visible through the 12x36 bins at SkySafari’s mag 10.1 but I wasn’t completely dark adapted and the moon had risen.. Epsilon CrB easy to locate along with the three surrounding scalene triangle stars of HD142898, HD143272 & AL CrB; all between 8-8.5 mag. Needs to go soon though or I’ll lose it over the rooftops!

 

[Tomatobro]

During a discussion about what the star will look like in the near future I realised that the star shown in the picture is not the star that will erupt. Its yellow colour suggests that this is the red giant that is giving up its material to a smaller companion. I took 120 twenty second subs to see if I could see any signs of the short term variability but clicking through the subs I don't think I can see any signs of dimming (or brightening).

 

[JeremyS]

2 hours ago, Tomatobro said:

During a discussion about what the star will look like in the near future I realised that the star shown in the picture is not the star that will erupt. Its yellow colour suggests that this is the red giant that is giving up its material to a smaller companion. I took 120 twenty second subs to see if I could see any signs of the short term variability but clicking through the subs I don't think I can see any signs of dimming (or brightening).

 

Actually neither star will erupt. As you pointed out, this is a double star comprising a red giant on a 227 day orbit around a white dwarf. The giant loses mass (hydrogen) to the white dwarf. At some point, sufficient material builds up on the surface of the WD for a thermonuclear runaway to occur. This is the eruption - it’s on the surface. Only a small amount of material is involved and is blown away into space. The two stars remain and the mass transfer continues for another ~80 years until it happens again.

Short term very small brightness  variations over a few minutes can sometimes be seen as the transfer of material is lumpy, not completely continuous.

Edited Monday at 19:57 by JeremyS

[michael.h.f.wilkinson]

I keep a close watch on T CrB with the big Helios LightQuest 16x80 bins. No luck yet, as you will no doubt know

 

[Tomatobro]

On the evening of the 29th I decided to go deep on the blaze star to see what else was in the field of view. Star is still behaving itself (the only one in the image with diffraction spikes)

[MalcolmP]

4 hours ago, Tomatobro said:

 to see what else was in the field of view. 

Interesting !
Is that a cloud of stuff given off in previous eruption or just stuff 'tween us and it, I wonder.    It is not centered on T but what is its proper motion,   in the last 80y ? , , ,
Edit , from wikip : Proper motion (μ) RA: −4.220 mas/yr Dec.: 12.364 mas/yr
Sadly the image will not platesolve in ASAP so determining where -80 times back from J2000 might be a tad hard on the old brain cell ! not to mention is mas milli or (μ)micro arcsec per year ?  I may be gone some time , , ,   and would the cloud be co-moving or slowed by the interstellar medium ?

 

Edited 14 hours ago by MalcolmP

[JeremyS]

4 hours ago, MalcolmP said:

Interesting !
Is that a cloud of stuff given off in previous eruption or just stuff 'tween us and it, I wonder.    It is not centered on T but what is its proper motion,   in the last 80y ? , , ,
Edit , from wikip : Proper motion (μ) RA: −4.220 mas/yr Dec.: 12.364 mas/yr
Sadly the image will not platesolve in ASAP so determining where -80 times back from J2000 might be a tad hard on the old brain cell ! not to mention is mas milli or (μ)micro arcsec per year ?  I may be gone some time , , ,   and would the cloud be co-moving or slowed by the interstellar medium ?

 

There is no nebulosity in this part of the sky. 
Some novae have “shells” surrounding them, caused by blown off material, but I don’t think one has been imaged in the case of T CrB.

[MalcolmP]

1 hour ago, JeremyS said:

but I don’t think one has been imaged in the case of T CrB.

Until now   ?  or just an artifact ? A gentle stretch in Gimp, somewhat more vigorous in ASTAP : 

 

 

 

Edited 11 hours ago by MalcolmP

[Gfamily]

6 hours ago, MalcolmP said:

Interesting !
Is that a cloud of stuff given off in previous eruption or just stuff 'tween us and it, I wonder.    It is not centered on T but what is its proper motion,   in the last 80y ? , , ,
Edit , from wikip : Proper motion (μ) RA: −4.220 mas/yr Dec.: 12.364 mas/yr
Sadly the image will not platesolve in ASAP so determining where -80 times back from J2000 might be a tad hard on the old brain cell ! not to mention is mas milli or (μ)micro arcsec per year ?  I may be gone some time , , ,   and would the cloud be co-moving or slowed by the interstellar medium ?

Astrometry was able to solve it, giving the fov as about 19x12 arc minutes. 

The enhanced view suggests the 'cloud' is about 10 arc minutes diameter, and T CrB is about 2,3 arc minutes from its centre.

It;s a Saturday night, and I've had some wine and some whisky, but I calculate, that if the Proper motion is 12mas/year in declination, then whatever created the 'cloud' (if it was associated with the Nova) would have been about 11,500 years ago.

I'm in the middle of preparing a talk about T CrB for my Astro Group - and from what I can gather, the more recent cycles of Novae have processed about 0.1 Jupiter mass of 'stuff' into the interstellar medium (while retaining about 0.9 Jupiter mass on the accreting WD per cycle) - so either something very big happened 11.5K years ago, or 'the cloud' is a Line of Sight coincidence

 

 

Edited 10 hours ago by Gfamily
Typos due to whisky and wine (even had to correct the reason for edit)

[Geoff Lister]

For looking at T CrB, I normally use my Seestar S50 for 1 to 2 minutes (stacking 6 to 12, 10-second,  FIT frames). The sky atlas uses IC 4587 as a marker, but at magnitude 14-ish, I do not see any detail. Clearly, I need to stack for a lot longer.

Geoff

[Gfamily]

2 hours ago, Geoff Lister said:

For looking at T CrB, I normally use my Seestar S50 for 1 to 2 minutes (stacking 6 to 12, 10-second,  FIT frames). The sky atlas uses IC 4587 as a marker, but at magnitude 14-ish, I do not see any detail. Clearly, I need to stack for a lot longer.

Geoff

Same here, though I take 3 minute exposures, just to keep an eye on it whenever I can.  I connect the SeeStar App to Sky Safari so that I can use the better Search facility to GOTO T CrB directly.

IC 4587 is definitely a marginal detection though 

(very cropped image)