Astronomers are producing spectras of the new star Nova Delphini 2013. I have been very busy lately and last night I finally I got down to do it.
Equipment:
Mount: Vixen SXD with NexSXD and NexStar HC. Polar aligned and drift aligned.
Scope: Megrez 90
Camera: DMK 41AU02.AS
Spectroscopy with Star Analyser 100 diffraction grating
Software: RSpec software
Before slewing scope to Nova Del, I checked the GOTO accuracy on a couple of known stars (Altair, Deneb, SAO 106230, SAO70474) to ensure mount slewed accurately.
Next I used NexStar HC to slew to the coordinates of Nova Del - 20:23:30.7, +20:46:06
The video capture from the DMK camera is processed using the RSpec software.
The imaging was done last night (25 Aug 13) at about 10:50 pm. At its brightest this new star had mag 4.8 on 18 Aug 13. It has been fading since. Last night it was around visual magnitude 6.2. Here is the captured still from the video:
It was exciting to see how the emission signature of the Balmer series. RSpec was used to reduce the data. Its spectra showed very strong H-alpha & H-beta emissions, confirming its nova status.
Prior to the Nova Del capture, I had calibrated the SA100 using Vega as the calibration star.
Nova Del 2013 - Spectrum Captured Here in Singapore
Re: Nova Del 2013 - Spectrum Captured Here in Singapore
Good job! Thanks for sharing your methods and results!
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email: gary[at]astro.sg
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"The importance of a telescope is not how big it is, how well made it is.
It is how many people, less fortunate than you, got to look through it."
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email: gary[at]astro.sg
twitter: @astrosg
"The importance of a telescope is not how big it is, how well made it is.
It is how many people, less fortunate than you, got to look through it."
-- John Dobson.
Re: Nova Del 2013 - Spectrum Captured Here in Singapore
Really cool... Thanks for sharing!
Awesome SNR! sharp peaks! ...is it a HI peak I see on the left?
Does seem like some others did get the peak around 430nm too!
http://www.spectro-aras.com/forum/viewt ... =682#p2609
http://www.spectro-aras.com/forum/viewt ... t=10#p2618
Re: Nova Del 2013 - Spectrum Captured Here in Singapore
Found this an interesting read too!
http://www.spectro-aras.com/forum/viewt ... t=20#p2626
http://www.spectro-aras.com/forum/viewt ... t=20#p2626
Comments from Steve Shore :
Francois asked that I bore you all with some explanation of what's
happening in these data and perhaps to give you all some idea of what
the physical picture is. It's a pleasure, also because it's a chance
to say thank you to all of you for this amazing, invaluable effort.
Once the smoke clears (well, after possible dust formation?), we'll
have a chance to work through all of this for the eventual complete
analyses. You're all involved with that.
First, this is a stage not often accessed in the optical, even less in
the ultraviolet. In the first stage, after the explosion (that we
don't see), the ejected outer layer of the white dwarf expand
hypersonically and cool. Two things. First, this is a mixture of the
stuff that was accreted on the WD during the pre-nova stage, when it
sits inside an accretion disk from the companion and like a garbage
disposal just accumulates the stuff. Once a sufficient pileup occurs,
the compressed layer can initiate nuclear reactions and explode (well,
this is the surface, not the center, so there's nothing to constrain
the event). BUT there's a question even here. Theignition of the
nuclear fuel is like a flame, in fact physically it's very close, and
propagates like a flame through the envelope. This, in turn, provokes
a buoyant mixing (to avoid the word "boiling" but it's a similar thing)
that also dredges material from deeper layers. A major uncertainty, of
almost cosmological importance, is how much of that mixed matter is
blown off and whether the WD mass increases or decreases. But that's
for another time.
For this stage, the explosion throws the gas off like a shell but with
a catch, the velocity depends on radius because the range of velocities
is ballistic and within an interval from the escape velocity to
whatever can be reached by the energy of the explosion. So you will
see velocities up to thousands of km/s. On this, a word of caution.
I'll always, in any of these notes, emphasize that what you see is NOT
the whole story. The ejecta are not completely transparent at all
wavelengths and you see to different depths of this fog -- just like a
fog -- depending on whether you're in the lines, continuum, the optical
or UV or IR -- in other words, a radiographic image of a human is
similar. You see to the depth from which the light can escape to you,
the surface -- the "photosphere" to those who want to be technical --
is wavelength dependent.
The same with the velocities. You see different line profiles on, for
instance, each Balmer line. Since the sequence from H-alpha to beta
and so on. is also one of intrinsic opacity (strength) you see deeper
in H-gamma than H-alpha and the line is formed mainly ("weighted
toward") the inner ejecta. So the combined line profiles, viewed in
velocity, are the probe -- tomorgraphy -- of the ejecta. With this you
can look for structure, dynamics, even variable abundances. The trick
is following the seqeunces and seeing how each part of the spectrum
develops. The Fe lines appear because the UV is opaque and the
absorption at high energy excited the optical (low energy) lines. The
same for the He and Balmer lines. In all cases, the classes (Fe, He/N)
are not anything but descritpicve of this stage.
The spectra you all got last night were from the fireball, the initial
stage of the expansion that is hard to catch. Now you'll see the next
pass, as the ejecta start to recombine and turn into a dense "fog".
Then, as they thin out (weeks from now, likely) the emission will
appear again but in the first stage the lines pass from ionized and He
and H to those of more easily ionzed heavy metals that would have been
too ionized to observe in the fireball.
I hope tis helps. It's just the star, if there's anything anyone would
like to see or if anyone has questions or comments, youknow I'm always
online (shore@df.unipi.it) even at the risk of filling all of our
mailboxes.
steve
Re: Nova Del 2013 - Spectrum Captured Here in Singapore
Nice work Alfred! This is real science man!
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Re: Nova Del 2013 - Spectrum Captured Here in Singapore
Excellent work, Alfred! I've not done specstroscopy of a star before, didn't know we could get such clear light spectra and good data using just a 90mm scope and a grating. I would like to see your set-up one day, how it works etc. Can you demo it to us? I think I shall try out stellar specstroscopy too.
Qixiang: Thanks for sharing the quote. I have a rough idea what causes a white dwaft to go nova, but that article could have been written in Greek. I think I need to sign up for a course in astro physics!
Qixiang: Thanks for sharing the quote. I have a rough idea what causes a white dwaft to go nova, but that article could have been written in Greek. I think I need to sign up for a course in astro physics!
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Re: Nova Del 2013 - Spectrum Captured Here in Singapore
Thanks for the responses.
Cataclysm - for your encouragement
Starfinder - I use the Star Analyser 100 (http://www.rspec-astro.com/star-analyser/ I would be glad to show you my setup.
The Nova Del 2013 spectrum taken by me on 25 Aug was featured by Tom Field, the author of RSpec (Real-Time Astronomical Spectroscopy) http://www.rspec-astro.com/sample-projects/#novadel
Qixiang - I have been discussing and learning from several experts. Have also read Steve Shore's article. Thanks for sharing it. I have checked with the work of other astronomers and updated the labelling on the spectrum.
Added on the left are the H-Gamma 4341, FeII 4529 and FeII 5250. These FeII lines confirm that this star is an Fe II nova rather than an He/Ne nova.
Absorption line 6325 is near to strong SiII 6347 absorption lines identified by Steve Shore and team at http://www.astrosurf.com/aras/novae/Nova2013Del.html. However I am mindful it may not be Si II
I still can't figure out what 7290 is
Alfred
Cataclysm - for your encouragement
Starfinder - I use the Star Analyser 100 (http://www.rspec-astro.com/star-analyser/ I would be glad to show you my setup.
The Nova Del 2013 spectrum taken by me on 25 Aug was featured by Tom Field, the author of RSpec (Real-Time Astronomical Spectroscopy) http://www.rspec-astro.com/sample-projects/#novadel
Qixiang - I have been discussing and learning from several experts. Have also read Steve Shore's article. Thanks for sharing it. I have checked with the work of other astronomers and updated the labelling on the spectrum.
Added on the left are the H-Gamma 4341, FeII 4529 and FeII 5250. These FeII lines confirm that this star is an Fe II nova rather than an He/Ne nova.
Absorption line 6325 is near to strong SiII 6347 absorption lines identified by Steve Shore and team at http://www.astrosurf.com/aras/novae/Nova2013Del.html. However I am mindful it may not be Si II
I still can't figure out what 7290 is
Alfred
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Re: Nova Del 2013 - Spectrum Captured Here in Singapore
Excellent effort Alfred. You have just become a "Singapore Observatory"....probably the first in the world with a tiny megrez90 instead of the large mirror elsewhere!
Those graphs made me want to watch "Contact" again (for the xx time!)
Those graphs made me want to watch "Contact" again (for the xx time!)
The Boldly Go Where No Meade Has Gone Before
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Re: Nova Del 2013 - Spectrum Captured Here in Singapore
Hi,Alfred
Good work with a supersteady mount with a tack sharp telescope.Without tracking this is
not possible right?Only Sirius,Sun,moon,meteor-fireball; possible without tracking.Anyway you are the FIRST in Singapore --to what I know---to take the spectra of a supernova.Congrads.
Good work with a supersteady mount with a tack sharp telescope.Without tracking this is
not possible right?Only Sirius,Sun,moon,meteor-fireball; possible without tracking.Anyway you are the FIRST in Singapore --to what I know---to take the spectra of a supernova.Congrads.
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Re: Nova Del 2013 - Spectrum Captured Here in Singapore
Hi Airconvent and Mr Chia - Thanks for your kind words.
Nova Delphini 2013 appears to be a "slow nova" type - it may stay around for months. It started at magnitude +6.8 on 14 Aug 13 and peaked at +4.3. When I first imaged it on 25 Aug 13 it was about 6.2, last night it was about +6.5. Based on past observations of similar type of nova, it may brighten up again. So keeping watching !!
Alfred
Nova Delphini 2013 appears to be a "slow nova" type - it may stay around for months. It started at magnitude +6.8 on 14 Aug 13 and peaked at +4.3. When I first imaged it on 25 Aug 13 it was about 6.2, last night it was about +6.5. Based on past observations of similar type of nova, it may brighten up again. So keeping watching !!
Alfred