New black hole binary in outburst (Mag 12.5 in Oph)

Information about outbursts of eruptive stars, Be activity, ...

New black hole binary in outburst (Mag 12.5 in Oph)

Postby Francois Teyssier » Sat Mar 17, 2018 7:16 am

MAXI J1820+070 is a new X-ray transient discovered on 2018 March 11 12:50
UT by MAXI (ATel #11399)
It has been associated with a bright optical transient
ASASSN-18ey (ATel #11400) in Ophiucus.


AD (2000) : 18 20 21.95
DE (2000) : +07 11 07.3

The observations show rapid brightening, fast optical variability.
Current magnitude (V) = 12.5

The observations are consistent with a black hole X-ray binary in the hard state


Optical spectra show

strong, broad H-alpha emission
and weaker emission from He I 5875 and the Bowen blend.
The H-alpha has a FWHM of about 1150 km/s. It is asymmetric but not clearly double-peaked
This FWHM is relatively low for a black hole X-ray transient,
suggesting either that the system has a long period associated with an evolved donor or that it is relatively face-on.
here are no obvious absorption features in the spectrum, indicating that continuum is dominated by the accretion disk.
(ATel #11424)

presence of a broad, asymmetric H-alpha emission line
Also detected broad H-beta, H-gamma, and H-delta absorption with emission lines in the center,
characteristic of an accretion disk in outburst.
He II 4686 (with EW = -1.7 Ang) is seen on top of the continuum
(ATel #11425)


Spectroscopy of MAXI J1820+070 is strongly encouraged.
An ideal target in the morning sky for Alpy, LISA and other low resolution spectroscopes
Observations will help to understand the intriguing nature of this source

Spectra will be added to ARAS Eruptive stars database
Send spectra to francoismathieu.teyssier at bbox.fr for inclusion in the database
Use MAXI J1820+70 in the fit header


François Teyssier
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Re: New black hole binary in outburst (Mag 12.5 in Oph)

Postby Forrest Sims » Thu Mar 22, 2018 12:06 am

Greetings!

Spectrum data from last night for MAXI J1820+70 also now apparently known as ASASSN-18ey.

This was tricky catching it after the clouds cleared away and before dawn. This target stood out quite brightly in the place predicted by the AAVSO Chart. I was able to get 6 usable 300sec exposures of the Target before the sky background became too strong. I took 7 30 second images of the A0III Reference star HD181470 for creating the Response curve correction. This target would certainly have benefited from longer exposures if time had allowed.

Thanks
Woody
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maxij1820+70_20180321_514_Forrest Sims.png
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Re: New black hole binary in outburst (Mag 12.5 in Oph)

Postby Francois Teyssier » Sat Mar 24, 2018 5:44 am

That's excellent, Woody
Typical spectrum of a dwarf nova in outburst
It could be a polar, according to Steve
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Re: New black hole binary in outburst (Mag 12.5 in Oph)

Postby Robin Leadbeater » Tue Mar 27, 2018 6:39 pm

A professional spectrum has just been posted on TNS by the ePESSTO team
https://wis-tns.weizmann.ac.il/object/2018amn

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Re: New black hole binary in outburst (Mag 12.5 in Oph)

Postby Forrest Sims » Thu Apr 12, 2018 12:24 pm

Here is my data from this morning on ASASSN-18ey = MAXI J1820+070. According to the AAVSO Alert notice 630 there is a "blitz" campaign for two nights (thru 13 April) on this object. They want high cadence photometry. But maybe some 600sec images of the spectrum would be of interest.

Cheers!
Woody
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asassn-18ey_20180412_438_Forrest Sims anotated.png
asassn-18ey_20180412_438_Forrest Sims anotated.png (36.6 KiB) Viewed 1110 times
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Re: New black hole binary in outburst (Mag 12.5 in Oph)

Postby Joan Guarro Flo » Thu Apr 12, 2018 3:05 pm

Good job Forrest !!

I can't was observed more on last days Nova CMa 2018, because it's cloudy and raining. Here the weather don't will better until next Sunday night.

Regards, Joan.
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Re: New black hole binary in outburst (Mag 12.5 in Oph)

Postby Peter Somogyi » Sat Apr 14, 2018 4:04 pm

Hi Woody,

You have a nice and valuable serie!
Let me extend it with a fresh result of today's morning:
maxij1820+070_20180414_066_PSO.png

Conditions were good (target high enough), more of us should be able to follow.

Cheers,
Peter
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Re: New black hole binary in outburst (Mag 12.5 in Oph)

Postby Peter Somogyi » Wed Jun 27, 2018 8:48 pm

Hello,

Seeing observers activity on this object again, revisited it the last Sunday morning:
maxij1820+070.png
maxij1820+070.png (104.72 KiB) Viewed 696 times

The HeI lines have separated clearly.
Exposures info:
2018.04.14 (JD=2458222.5982): 9 x 600 sec
2018.05.05 (JD=2458244.4973): 5 x 1200 sec
2018.06.24 (JD=2458293.5516): 3 x 1200 sec (of 10 min clouds)

Peter
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Re: New black hole binary in outburst (Mag 12.5 in Oph)

Postby Peter Somogyi » Thu Jun 28, 2018 6:33 am

+ Forgot to add:
http://www.astronomerstelegram.org/?read=11756
=> https://cbastro.org/the-astronomers-telegram/2018-june/
=> [...] "The phase stability of the 0.703 d wave makes it a good candidate for the orbital period of the underlying compact binary, although other interpretations (superhump? precession?) are possible. Spectroscopic observation could test this hypothesis, and ascertain the dominant light source in the binary."

Of course, my summer time window + poor horizon access not enough to check this 0.703d. (I am suspecting the large continuum changes doing that.)
Perhaps someone else (or more of us - multiple nights) could do it.

Peter
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Re: New black hole binary in outburst (Mag 12.5 in Oph)

Postby James Foster » Thu Jun 28, 2018 8:52 pm

Here is my best spectra of ASASSN-18ey taken from Mt. Pinos, CA last week with a LISA spectroscope on a 33cm aperture classical cassegrain reflector (1-Hr exposure):
Image
The O1 line at 5577A is terlluric. Only very noticeable lines are H-Alpha, H-Beta, & the He II(4685.7A).

James
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