Eta Carinae - Brightening??????

[Merlin66]

I just noted on a thread over here in the UK that it was suggested the Eta was "brightening" - never heard or seen anything.... anyone confirm or has details???

Ken

[CoolhandJo]

Funny you should mention that! Check out what "Ausie Observer" posted in this thread! Claims Eta Carina is brighter !

http://stargazerslounge.com/picture-week-competitions/102025-picture-week-18-04-10-a.html

[Suzy]

Funny you should mention this. I have been studying Eta Carinae for the last 4 months and three weeks ago I noticed that the star and it's associated nebula was amazingly bright. I have been searching ever since for any news on this but to no avail, until I came across this thread. Is there any information out there on it? As I'm new to this hobby (4 months), I just wasn't sure, but I knew that night it was spectacular. Unfortunately, since that observation, clouds and bad weather since have gotten in the way of me being able to take another look.

[bojan]

Hmmm it must be something different... perhaps just your perception.
Nebula is huge (will check later for actual size) and any transient on eta itself (sudden brightening) will take quite some time to propagate through the nebula.

EDIT:
OK, found it.. the homunculus is ~40 light-days in diameter.. so, for the transient to propagate through would take couple of weeks.. so the nebula brightening (but delayed compared with eta itself) is plausible.

[PeterM]

If we are indeed (extremely) lucky in our lifetimes and we are to witness a Supernova in the MilkyWay then Eta Carinae would be a great candidate.
Since brightening back in around the late 1830s to early 1840s (it became as bright as about Sirius) it then faded to something like mag 8, I think and its brightness has been climbing since. Being estimated at 100-150 times the mass of the Sun then I guess if it goes, it goes Hypernova and at around 7500 light years away would certainly put on a nice show.
This is perhaps the most monitored star in the heavens both by professionals, amateur imagers and visual observers alike (see the links below).
Over the years I have often heard Kevin Dixon (SAS in Qld) talk of a brightening of the envelope that surrounds the star, people doubted him even when they looked at it , only to be followed by official confirmation on various sites of what he was seeing. So who knows, heck I haven't seen the sky in weeks. So maybe Suzy you have just seen the trailers so to speak before the main event, put me down for a ticket right in the front row. But don't observe it through a telescope as I understand from reading someones posts here a while ago its' concentrated laser like light would apparently be blinding, must find that post and use it as a programme of what to expect....let the show begin, on time please!

PeterM.

Radio outburst
http://www.astro.umd.edu/~white/images/eta_time_full.html

Optical monitoring

http://etacar.fcaglp.unlp.edu.ar/

[bojan]

Laser? no...
Supernova (hypernova) light will not be collimated like laser (Laser light is coherent and it has only one wavelength.. that is why it can be dangerous because it can be focused on a very small area of the retina).
Also, laser output power considered as dangerous is close to 1mW.. I am not sure now what is the power flux of a star of, say, 0 mag.. ( i have seen the numbers somewhere) but I feel it is way lower than 1mW (possibly pW? or even less)

[PeterM]

Thanks Bojan,
I have often wondered about that after reading in a well known amateurs post here on Ice In Space. I may have taken liberties on the "laser like" I think it was maybe concentrated into a point source but it was clear re the blinding light, which I know they backed up with some research. Unfortunately they don't post here anymore and just did a search and their posts seem to have all gone.
PeterM.

[bojan]

Here are some numbers for the start:
Sun's output is 1.3kW/m2 (above atmosphere, of course).
Sun's apparent magnitude is -29.
So, star of magnitude 0 has 2.5^29 lowr power flux, which is 0.000000003746994889972252672 W/m2, or 3.7nW/m2
This means, 10" mirror will collect ~0.23nW... very small power indeed, and this will be over the whole spectral bandwidth (so with apsorption in the atmosphere, this will be way below this value).
Now, this is for a star of mag 0.
It all depends how bright eta will be when it goes off :-)

[astroron]

Surely it wont be mag 5.4 one second, then mag -8 the next?
From what I understand it would take a little time to brighten to it's brightest?

[astroron]

The common perception is that Eta is a double star and does brighten over a five year period but I think more in the infrared.
It has been brightening over the last maybe 20 years or so?
From my place here in Cambroon I have noticed that it is now quite easy to see the Star! naked eye, I could not see it naked eye when I first moved here in 1990.
That said I would hazard a guess that the brightening seen at the present moment is just the quality of the Transparency/seeing by the observer.
I would imagine that the professionals would have noticed by now and it would be broadcast to the astronomical community:thumbsup:

[PeterM]

I found this link in which Sydney Observatories Nick Lomb also appears to raise the possibility of danger to eyesight. Interesting, has me digging for more info now to see how this notion comes about. Could there be more to this than meets the eye? Should have done it when the other person posted I guess.
http://www.sydneyobservatory.com.au/blog/?p=344

PS. Ron raises a very good point re seeing and transparency at the time of observations. Perhaps checking any perceived brightness increases against the links provided and see how well they match might give an indication.



PeterM.

[astroron]

Peter just a bit of news, Nick Lomb has retired, but still does a bit of on line work:thumbsup:

[Steffen]

Hmm, what magnitude is it supposed to reach then? The Moon at -13m isn't dangerous to the naked eye, the Sun at -27m obviously is. Is Eta Carinae expected to go brighter than -13m when is goes supernova??

Cheers
Steffen.

[bojan]

The problem is also, Moon light is spread over large area. while Eta will be point-like.. and if all the light form it is focussed on single receptor in the eye, it may burn it (provided there is enough power for this to happen).
-13m may be dangerous it this respect, especially if telescope is used. I will do some more calc.

[PeterM]

Eta, at 4 million times brighter than the Sun so it will be bright, incredible. I've seen estimates at least as bright (not as large) as the full Moon, being able to read by it at night etc. Seems SN2006gy (NGC1260) about the same mass as Eta, instantly put out as much energy as the Sun does in 10 billion years.

PeterM.

[astroron]

Is brightness equated with heat? I have observed a mag -7 iridium flair only maybe for a couple of seconds? and it did not as far as I am aware do any damage.
Would looking at a point source such as a mag minus thirteen star actually burn your eye?
I have had someone set off a camera flash very close to my 16" scope when I was observing, which other than being like the effect at looking at the Moon was all the effect I got.

[PeterM]

I think its more concentrating that amount of light onto the eye (ie Moon) as a point source, it will damage your eye. Happy to be corrected on this.
PeterM.

[astroron]

If I was to Look at the Full Moon through my 16" with a 9 mm eyepiece but concentrated the light through a pin hole would that not be the same thing as looking at a star exploding 7000 lights away?
I know the Moon light is reflected light, maybe that could be the difference

PS I am not going to try it

[PeterM]

Suppose could be same as saying "equal in brightness to a 150 watt spotlight" as in your security lights. Ok you can look at that for a short while before it becomes uncomfortable, but squeeze all that light into a point source and look at it through a telescope and I think it would be more than uncomfortable.
PeterM.

[bojan]

Guys, it all depends on power density on the retina and amount of energy delivered per square mm of retina..
When I'm through with some basic math I will be back with numbers...

[Suzy]

I have rung the Sir Thomas Brisbane Planetarium and spoke with an astronomer regarding Eta Carinae brightening. He told me he will investigate it further and get back to me. Will keep you informed of the outcome.

[space oddity]

Bit early in the morning for maths, but need some extra info. Assuming Eta Carina is 7,500 LY away and earth is about 8.4 light minutes from the sun,eta carina's light is diluted 2.2 x 10 to the power 17 compared with our sun. The typical scenario is that a supernova shines as bright while it is exploding as the rest of the galaxy put together, gives 100 billion times the light of an average star 10 to the power 11 .This equates to the brightness 1/2.2 x 10 to the power 6. This is 15 orders of magnitude. Assuming the sun is an average star(this is the extra info needed- what is the percentage difference), this equates to mag 29-15 =mag- 14 at supernova, 2 mags brighter than the full moon.Depending on the amount of infra red, it could be spectacular but not blinding. Brightness will be akin to looking at the full moon through small to medium sized binoculars. I have to head off for work soon, so I will pass the batton on to the next person to fine tune the maths and iron out my assumtions.
Maybe Eta Carina will go supernova for the star party- what a" blast" that would be:P.

[space oddity]

Finally made it home after an unexpectedly busy day at work. The Sunday is to compensate for taking the weekend off and hopefully the Friday for the star party. Researching on the web, a supernova of eta carina if a type 1a should reach a peak magnitude of -4. Tycho's supernova of 1572 ,also at around 7,500 LY away reached a peak of -4. Looks like the early morning maths may have been up to 10 orders of magnitude off the money:confused2:. Looking at the subject on the net, other calculations give -7 magnitude. Any way you look at it, it will be having us all licking our chops.

[PeterM]

Tychos star is listed as a Type 1a event, that is the incineration of a White Dwarf exceeding 1.4 solar mass. The "new star" was recorded at the time as quite red and studies now suggest redder than normal, probably from the absorption of light by interstellar dust. Eta is estimated at 100-150 times solar mass and expected to be more likely a Hypernova, never a Type 1a - now that would be a "blast" you are right there.
How does this all affect the chalkboard?

PeterM.

[bojan]

I am still trying to find in various ANZ standards some data on safety levels for laser radiation, to be able to calculate (roughly) the effects of staring at -13m star through telescope and unaided eye.
It will happen, eventually (me finding the right standard, I mean).
But, for the star 0m the "solar constant" is 25nW/m2 (the previous result of 3.7 nW was based on Sun being -29, but is is actually -27.
10" telescope will collect 6.3nW

-13m in 10" telescope will have a power flux close to 940uW, almost 1mW !!

That is A LOT !! And definitely above safe level.

You can look at -13m star without aid, but through any telescope it can fry your retina (provided the image is focussed).

[Merlin66]

Isn't that about the same magnitude as a Full moon?

[bojan]

It is, but full Moon power output is spread over 0.5° diameter circle (on retina this is will be 0.05mm or so)
So power density on the retina can not exceed safe level, while star image (all that power concentrated on one small area) potentially could, because it will be concentrated on couple of cells only.
Also, I am presenting numbers for effects using 10" telescope. This will definitely be dangerous.

[Merlin66]

I understood the sun, moon, planets (faint galaxies)etc were integrated magnitudes?
http://en.wikipedia.org/wiki/Apparent_magnitude

[bojan]

Yes they are...

But again, it is about power density at the retina - how much power (in joules per second or W) is falling on the unit area (mm2) , and if this value is high, power can not be dissipated fast enough (factors here are thermal conductivity of the retina tissue, blood flow and so on) and the temperature in that spot goes up (until a thermal balance is achieved again).

In case of point-like source (star), all incoming light (power received by eye through the telescope) is focussed into one spot (or very small area.. better the optical system, smaller the focal point) so the power density could be very high and this could result in high temperatures (on that small area).

Sun and Moon are extended light sources, their images on the retina are relatively large and the power density (W/mm2) or illumination is much lower, so the thermal power is spread over larger area and is less dangerous (in Moon's case only of course), especially if higher magnifications are used.

All this is of course idealised case - my (rough) calculation is based on solar constant and assumption that all power is received and converted into heat, and I assumed the spectral density of eta when it blows up will be similar to Sun's light - which it won't, of course - I think the spectral peak will be in UV, so the thermal effect will be smaller (because of Earth's atmosphere).
Also, if any kind of filter is used at the telescope end, the effect will be diminished further .

[Steffen]

If we don't close down this thread soon we'll end up having telescopes of 10" and larger banned in Australia… :P

Cheers
Steffen.

[bojan]

You are probably right :eyepop:
Lets stop ;)

[astroron]

The point of the Thread was lost in all this mathematical exercise;)
IS Eta Carina Brightening:question::question::que stion:

[bojan]

No. Or, not significantly I would say..
I took an image of eta in January this year.. and I checked it couple of nights ago, same area, same equipment, same exposure time.
Unfortunately, I made couple of mistakes during imaging session.. first stack was destroyed because the mount did not track.. then I repeated the photo session, but it seems I moved the focus ring, then I went in the house because the mosquitoes were quite hungry then the clouds rolled in and only then I noticed the images were badly out of focus..
But I was still able to compare the general appearance of photos between January and two days ago, and eta didn't look significantly brighter.

[Suzy]

The astronomer from the Sir Thomas Brisbane Planetarium rang me back. He said that during that period, Eta Carinae got brighter from Mag. 4.65 to 4.55. and has been steadily getting brighter. It's not significant - not quite half a mag. But he did say it could have experienced a spike. He further went on to say that if there is an occurrence it is not necessarily released to the public straight away.

[duncan]

I wonder what was meant about "what the public has been told is not all that's there" in Suzys' post.?
Cheers,
Duncan;)

[Suzy]

He meant that if there is an occurrence it is not necessarily released to the public straight away. I do not know the time frame when they hold and release information. Apologies for not making that clearer. I will edit, so it make more sense.

Also interesting to know that variable star observations are carried out only once a fortnight. I only just found this out.

[duncan]

Thanks for the explanation Suzy. Might be something really interesting on the horizon.
Cheers,
Duncan:)

[Octane]

I want to see this in a binoviewer hooked up to two 20" mirrors. Ooh, yes, that's the ticket.

H

[Shano592]

Wasn't there one of those on eBay about a year ago, H?

[RobF]

I'm sure I've read recently about Eta brightening in recent years. Maybe it is the current S&T? Will have to check.

This is an interesting read:
http://www.astrosociety.org/pubs/mercury/9804/eta.html

[Suzy]

That was a really top read Rob! I'm going to print it out and file it with my other Eta Carina stuff. :thumbsup:

[PeterM]

That certainly was a great read.

Suzy I found this timeline that may be useful to include with your Eta Carina stuff. I wonder, if you are going to Astrofest perhaps you might consider a short presentation on your continuing passion for this, just a thought.

PeterM.

http://www.google.com.au/search?q=eta+carinae&hl=en&rlz=1G1GGLQ_ENAU375&prmd=iv&tbs=tl:1&tbo=u&ei=CIseTOvmFsmekQWw8LnNCw&sa=X&oi=timeline_result&ct=title&resnum=17&ved=0CFgQ5wIwEA

[Insane Climber]

Looks like it hit peak mag on june 19

http://varsao.com.ar/Curva_Eta_Carinae.htm

[RobF]

Most interesting.
I have to admit the sceptical scientist in me didn't think it likely the variations would be perceptible to the human eye, but it would seem those changes over the last 2 years definitely would be.

Hats off to those that noticed!

[luigi]

At the other side of the world, that is Argentina one of our observatories has been tracking Eta Carina for a while

Info and graphs here:
http://etacar.fcaglp.unlp.edu.ar/

http://etacar.fcaglp.unlp.edu.ar/plots/difaperV.png
V-relative brigthness increasing of the central region, relative to the complete Homunculus just after event

Hope this info helps!
(Updated up tu June 18th)

I'm not an expert but I think it is brightening but within expected rate for peaks and lows as seen in the last years. Nothing exceptional. (yet!)

[astroron]

Thanks Luis, but I cannot access either of those two sites you present:(

[MikeyB]

There must be some problem with your browser/internet link, Ron - Luis' links both work perfectly for me and the .png one is just to a picture of a graph.

[astroron]

Still no luck:shrug:

[RobF]

Links ok here too Ron - maybe slow to download for some reason?

[astroron]

This is what I get, when I click on the link:shrug:
DNS error occurred. Server cannot be found. The link may be broken.

Suggestion - search the Web:
Are you looking for: 1.The Rule (http://au.yhs.search.yahoo.com/avg/search?type=yahoo_avg_hs2-tb-webdns_au&fr=yhs-avg&p=The+Rule) 6.Eta (http://au.yhs.search.yahoo.com/avg/search?type=yahoo_avg_hs2-tb-webdns_au&fr=yhs-avg&p=Eta) 2.Bulletin Board (http://au.yhs.search.yahoo.com/avg/search?type=yahoo_avg_hs2-tb-webdns_au&fr=yhs-avg&p=Bulletin+Board) 7.Educational Supply (http://au.yhs.search.yahoo.com/avg/search?type=yahoo_avg_hs2-tb-webdns_au&fr=yhs-avg&p=Educational+Supply) 3.Chalkboard (http://au.yhs.search.yahoo.com/avg/search?type=yahoo_avg_hs2-tb-webdns_au&fr=yhs-avg&p=Chalkboard) 8.Printables (http://au.yhs.search.yahoo.com/avg/search?type=yahoo_avg_hs2-tb-webdns_au&fr=yhs-avg&p=Printables) 4.Classroom (http://au.yhs.search.yahoo.com/avg/search?type=yahoo_avg_hs2-tb-webdns_au&fr=yhs-avg&p=Classroom) 9.Chalkboards (http://au.yhs.search.yahoo.com/avg/search?type=yahoo_avg_hs2-tb-webdns_au&fr=yhs-avg&p=Chalkboards) 5.Human Skull (http://au.yhs.search.yahoo.com/avg/search?type=yahoo_avg_hs2-tb-webdns_au&fr=yhs-avg&p=Human+Skull) 10.3 Binder Ring (http://au.yhs.search.yahoo.com/avg/search?type=yahoo_avg_hs2-tb-webdns_au&fr=yhs-avg&p=3+Binder+Ring) You can try again by typing the URL here:

The page you are looking for is currently unavailable. The Web site might be experiencing technical difficulties, or you may need to adjust your browser settings.
Other options to try:

[bojan]

Links for for me as well...
http://etacar.fcaglp.unlp.edu.ar/plots/difaperV.png
http://etacar.fcaglp.unlp.edu.ar/

[astroron]

Bojan, your links don't work for me iether:shrug:
I will will get onto my server tomorrow to see if they are blocking this site:question:
Is it possible my security software is blocking this site:question:
Cheers

[bojan]

Sorry for typos, the links work for me :-)

It must be a problem with your ISP.. or something local.

[astroron]

Thanks Bojan.

[Suzy]

Jason, thankyou for that wonderful link! :thumbsup: Some really good info coming this way :).

Like Ron, I also can't get access those links either :shrug:. Response is the same as Ron's computer.

[Suzy]

Thankyou Peter so much for that link.:thumbsup:

Thankyou also for the kind invitation, I felt very special indeed! :D
As passionate as I am about this topic, I feel however there are plenty of others that could give this presentation more justice than I could, for I am just a beginner really. :)

[MrB]

I'm with Ron and Suzy, no go on those links.

The connection has timed out
The server at etacar.fcaglp.unlp.edu.ar is taking too long to respond.

[MikeyB]

Links are still working perfectly via Optus.

[Merlin66]

Anyone monitoring the spectrum of Eta????
If it "blows" we'll get the first light in the Southern Hemisphere - it would be a great catch for Australian observers......

[Glenpiper]

Hi Ken,

I monitored H alpha intermittently in 2009-10 but since late last year have been concentrating on a particular HeI line for the Royal Belgian Observatory ... all very steady in that region, so far.

Bernard

[Merlin66]

Glad to hear that!
I'm sure it will be spectacular when it "blows"; I have bets on with my wife that it will happen before they lower me into the ground (with my Genesis 4")
Which HeI line? What resolution is required?

[mr bruess]

Eta Carinae is an unstable star blowing out hot gases.
It is about 7500 light years away.
Its hydrogen fuel is running out and soon gravity will cause it self to collapse and blow apart in a gigantic explosion.
It is a supernova waiting to happen.
Nobody knows when it will blow up.it could happen now or in thousands of years.

[Merlin66]

Well, I figure I've got about twenty years left....so if I win my bet -it will blow some time before 2031 -March.

[petermead]

Hi,

First post here.

I have been stocking up on sunscreen so I can wear it at night. I figure there may be a big rush on when this star goes off...

:screwy:

But is there real evidence of Eta Carinae brightening?

Cheers,
Peter Mead

[MrB]

Hi Peter, welcome to IIS.

The answer you seek is on the first page of this thread.
One source of 'evidence' is here: http://etacar.fcaglp.unlp.edu.ar/

[Terry B]

Go to here
http://www.aavso.org/data/lcg
Enter "eta car" as the star.
Put the start date as 1/1/1590 and leave the other fields blank. (yes this is the correct year :D)
The light curve for the last 400 years will be displayed.

[astroron]

I followed your instructions and I got nothing:shrug:
could give us a screen shot as to what the display looks like before asking for plot?

[Suzy]

Ron, right at the top there is a menu displaying different requests. Once you have filled in the box criteria, you can then select from that menu. For example I found "View AAVSO Observations" very informative for a more detailed report consisting of days and times of the visual mag. observations.
Don't type in Eta Carinae - I have done this in the past and has gotten me no where :screwy:. Do as Terry said and type it as eta car.

Thanks for that very helpful link Terry. I never got too far with this site until now.

[astroron]

It worked this time,Thanks Suzy and Terry:thumbsup: