Dear Peter
I achieved a spectrum last night. It fits well with a Type 1a SN at maximum. See attached
Terry
Terry that is fabulous work, congratulations indeed. As you know I have sent some of your spectra to our contacts at Las Campanas for comment, they have responded that they are very good and will comment further in detail but are very time poor at the moment.
Why not send this to Dave Bishop as I am sure he would be delighted to include on the Bright Supernova Page http://www.rochesterastronomy.org/snimages/
I took time out from trying to hunt out 2012 DA14 (failed) to see if I could find this PSN through Sydney's light pollution and high cloud. 9x60sec, 127ED, Sony a77. Pretty rubbish, but Unimap tells me I have an object at the right RA/Dec.
With a field of 3.5x3.5 degrees and about five exposures to eliminate cosmic rays this system can cover a big area of sky in a short time. I do not know how sucessful blinking would be with such a large area full of stars.
I dont know how useful my system is for SN searching. These images may give you a better idea Peter. I did take a range of luminance images from 30 seconds to 2 minutes. One minute looked to be optimum.
The last image below is a crop from the one minute luminance stack.
I forgot to say you are welcome to use any of these images.
this is fantastic work very well done you spectra looks REALLY GOOD.I really do wish that I was able to achieve this.I have passed your link on to a few of the astronomers that I know quite well for their comments I will pass on their thoughts.
Hi Bert
This look like very interesting images I have been thinking of using a hyperstar for similar searching to give a larger field of view could you please let me know what type of scope/camera you are using for such images.BTW the supernova is easily seen in you images. Well done
Stu
Quote:
Originally Posted by avandonk
Congratulations to all the BOSS team. Here is my tiny contribution with some images.
Spent last night taking data with NGC5643 at the centre of my field.
This is a stack of five luminance images of sixty seconds each 5MB
With a field of 3.5x3.5 degrees and about five exposures to eliminate cosmic rays this system can cover a big area of sky in a short time. I do not know how sucessful blinking would be with such a large area full of stars.
I dont know how useful my system is for SN searching. These images may give you a better idea Peter. I did take a range of luminance images from 30 seconds to 2 minutes. One minute looked to be optimum.
The last image below is a crop from the one minute luminance stack.
I forgot to say you are welcome to use any of these images.
All,
its great to see all the activity that this discovery has generated, well done to all, I that wish I could contribute, but its too hard under all the clouds here in SE Qld!!!
Hi Bert
This look like very interesting images I have been thinking of using a hyperstar for similar searching to give a larger field of view could you please let me know what type of scope/camera you are using for such images.BTW the supernova is easily seen in you images. Well done
Stu
This is my new system Stu
Astrograph is an Officina Stellare RH200 which has a focal length of 600mm and is F3, yes F3! Clear aperture is 200mm.
FLI Atlas Focuser.
FLI ten position filter wheel CFW-3-10 with 50mm square filters.
Astrodon E series LRGB and HA, NII, SII and OIII 3nm NB filters. Also a continuum filter 5nm.
Camera is a FLI PL16803 which has a sensor size 36.8 X 36.8 mm.
The FoV of this system is 3.5 X 3.5 degrees.
Mount is a Software Bisque PMX.
With the PMX mount it is a trivial exercise to take images of the exact same area over many nights while the object/s is/are visible. The goto has an error of seven seconds of arc rms!
I have yet to master how to script automatically a set of target areas for multiple exposures. There is a huge amount I still have to master that this new system is capable of.
I am willing to spend some of my clear nights on taking images of galaxy clusters or areas the Boss team is not covering.
Maybe I could start off with one or two targets and see how it goes.
I realize the dedication needed to consistently monitor for SN's is not trivial. We imagers are a masochistic lot already, are we not?
Mati Morel has generated a good chart for the SN now which is available through the AAVSO web site. I'd be wary of the mag 11.7 comparison star shown on the chart, it doesn't look quite right but the others appear fine. I visually observed the supernova again this morning and at Feb 17.756 UT it was mag 11.7.
SN 2013aa seems quite remote into the halo of 5643, 2x beyond the last
visible traces of spiral arms and roughly 4x the virial radius. Even
though the spectral data recorded thus far and dist modulus indicate the
SN is part of the galaxy, it's the first time I recall a 1a occurring so
seemingly remote from its host galaxy. 5643 was included on several
watch lists of Sey2 galaxies for possible SN activity starting in 1997.
Proposals for HST time go back to 1995, so it's been an object of
curiosity for quite awhile. It's a dusty SBc with an an elongated and obscured core that doesn't fully meet Sey2 criteria (hence its designation "Sey2-like"). Now this, a 1a that to my understanding has
occurred far out in the galactic boonies where there's very low gas and
dust density, not much in the way of magnetohydodynamic turbulence, and no visible bar torque or recent interactivity with another high-mass object. Could 2013aa be in a faint dwarf orbiting 5643?
SN 2013aa seems quite remote into the halo of 5643, 2x beyond the last
visible traces of spiral arms and roughly 4x the virial radius. Even though the spectral data recorded thus far and dist modulus indicate the
SN is part of the galaxy, it's the first time I recall a 1a occurring so seemingly remote from its host galaxy.
......has occurred far out in the galactic boonies where there's very low gas and dust density, not much in the way of magnetohydodynamic turbulence, and no visible bar torque or recent interactivity with another high-mass object. Could 2013aa be in a faint dwarf orbiting 5643?
A very interesting comment, and it is very good to hear from someone in South Africa; a large proportion of our IIS members seem to come from Australia, and we don't get too many posts from SA. This is odd, as we share exactly the same sky!!
There has been a lot of talk in the recent literature about XUV ("extended ultraviolet") disks in spiral galaxies, as can be detected using the Far-Ultraviolet imaging band of the GALEX satellite;
It has been proven, from Galex FUV detections of star-forming knots found in the very outermost regions of spiral galaxies (the FUV bandpass is inordinately sensitive to current star formation), that star formation can occur a long way outside of the optically-bright disk of a spiral galaxy.
A good nearby example of this phenomenon is M81, in which the low-density intergalactic medium has nonetheless somehow managed to form knots of OB stars!!
As the wavelength-range and sensitivity of astronomical observations have progressively increased, there has been a tendency for astronomers to find ever more inter-galactic gas between the galaxies and ever more gas outside of the bright optically-evident bodies of galaxies. So astronomers now know of several sources of gas that can provide the raw materials for forming stars in the outermost parts of galaxies.
For instance:
- it has turned out to be the case that many elliptical galaxies are NOT gas-poor, as was the common so-called “knowledge”(actually a prejudice!) found in the textbooks about galaxies. There is often a massive interstellar medium of very hot X-ray emitting gas that surrounds an elliptical galaxy, and this gas could potentially cool enough to form new stars. There is also a colossal reservoir of very hot gas associated with many clusters of galaxies, often with more mass existing in the form of hot gas than is found in all of the stars of all of the galaxies.
- low column-density HI (neutral atomic Hydrogen gas) has been found in the outermost regions of many galaxies, and the total amount of this gas can be comparable to the amount of gas actually found within the prominent central regions of a galaxy. This gas was undetectable until very recently, due to its low density!
- Further evidence for the existence of large reservoirs of cold (and therefore, potentially star forming) gas existing outside of the obviously visible disk components of spiral galaxies can be found from considering the star-formation history of our own Galaxy; the Milky Way Galaxy has been forming stars steadily for all of its history, and the ongoing star-formation would have exhausted its total gas supply several times during its history, were there not some mechanism by which cold gas falls into the disk from above it and below it. The interstellar gas in spiral galaxies seems to be recharged by gas which is falling in from the halo of the spiral galaxy, or even perhaps falling in from intergalactic space.
- the intergalactic gas surrounding a galaxy, or the Low column-density gas that is actually associated with the outermost regions of a galaxy, can be caused to form new stars by the energetic effects of plasma beams originating in a central Active Galactic Nucleus, or by the energy of powerful shock waves that exit the disk of a spiral galaxy due to the effects of multiple supernovae.
For instance, in NGC 5128, the plasma beam from the central AGN has set off some modest star-formation in the outermost regions of this galaxy.
- Supershells (powerful shock waves, in a gaseous medium, coming from multiple supernovae) can expand outwards, reaching outwards to points which are a long way from the obvious bright disk component of a spiral galaxy, thereby providing adequate energy for the inception of star formation in clouds of cold gas existing in the outermost regions of galaxies.
One further point is that a galaxy does not have to look the same now as it did three billion years ago;
- there is evidence that a massive interstellar medium can be stripped from the outer parts of a disk galaxy by encounters with other galaxies or by the effects of "ram pressure stripping" of a galaxy's Interstellar Medium caused by high-velocity passages of the galaxy through a low density intergalactic medium. Thus, outermost stars and other outer features that are observed in a galaxy could be a residual of previous structures that no longer exist.
- Another process is also likely to exist, which affects a galaxy in the opposite way to the aforementioned exhaustion or stripping of gas from the outer regions of some galaxies;
the outer disks of spiral galaxies, and even the outer disks of elliptical galaxies(!!!) , can be gradually built up from the infall of gas!!
This seems to be happening in the S0/E galaxy NGC 1316, as was strongly indicated in a recent paper by Prof. Kenneth C. Freeman (of ANU) and colleagues.
Best regards,
madbadgalaxyman
Madbadgalaxyman's comment of the day;
"Yes, Virginia, elliptical galaxies do have disk components. Disks in elliptical galaxies just happen to be very faint, or very small in radius."
Last edited by madbadgalaxyman; 22-02-2013 at 12:42 PM.
SN 2013aa seems quite remote into the halo of 5643, 2x beyond the last
visible traces of spiral arms and roughly 4x the virial radius. Even
though the spectral data recorded thus far and dist modulus indicate the
SN is part of the galaxy, it's the first time I recall a 1a occurring so
seemingly remote from its host galaxy. 5643 was included on several
watch lists of Sey2 galaxies for possible SN activity starting in 1997.
Proposals for HST time go back to 1995, so it's been an object of
curiosity for quite awhile. It's a dusty SBc with an an elongated and obscured core that doesn't fully meet Sey2 criteria (hence its designation "Sey2-like"). Now this, a 1a that to my understanding has
occurred far out in the galactic boonies where there's very low gas and
dust density, not much in the way of magnetohydodynamic turbulence, and no visible bar torque or recent interactivity with another high-mass object. Could 2013aa be in a faint dwarf orbiting 5643?
Yes, good to hear from SA for a change, thanks Dana.
Your comment about a dwarf interests me because i was wondering the same thing a few days ago. So, here's a challenge.
Can anyone, with clearer skies than us in SE Queensland, conduct a verrry long exposure campaign at the galaxy to see if there are any traces of a dwarf there?....just thinking out loud....
Y
Your comment about a dwarf interests me because i was wondering the same thing a few days ago. So, here's a challenge.
Can anyone, with clearer skies than us in SE Queensland, conduct a verrry long exposure campaign at the galaxy to see if there are any traces of a dwarf there?....just thinking out loud....
Agreed, Greg, there could well be a dwarf galaxy there, which was the host galaxy of the supernova......
but, as I mentioned in my last post, there are several other ways for gas and star-formation (and supernovae!!) to occur in the distant outermost parts of a galaxy.
See, for instance, this intriguing study of the galaxy NGC 3108, which shows that a disk of gas and dust and newly-formed stars is gradually coalescing in its outer regions! An analogous process of "the extension of the stellar disk of a spiral galaxy to progressively greater radii" is believed to occur in some spiral galaxies.
Further to your interesting proposal, it is quite possible that super-deep amateur imaging would reveal Extremely Faint optically-luminous outer (stellar) disks in many spiral galaxies and even in many elliptical galaxies!
