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E&F in Trapezium Binaries?

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14 replies to this topic

#1 Migwan

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Posted 12 January 2018 - 07:10 PM

I asked this in a thread in Observing but didn't get an answer so I'm dropping it in here. 

 

I caught both the E & F stars last February in Tx with my 2080.  Didn't know what to make of it as I wasn't aware of them before that.   I took a peek for them last week with my 1100 here MI and couldn't see them.  Seeing was fair and I expected to see them. (Though the seeing was not as good I had 3" of aperture.)

 

In the Sky&Telescope article that DLuders linked they state that these are binaries:

 

"They're both eclipsing binaries: V1016 Ori ranges from magnitude 6.7 to 7.7 over a period of 65 days and BM Ori from 7.9 to 8.7 every 6.5 days. With its much shorter period, it should be relatively easy to catch BM at both maximum and minimum sometime this season."

 

So I am wondering if it was poor seeing or do these stars sneak ought of sight???

 

jd



#2 PETER DREW

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Posted 12 January 2018 - 07:41 PM

They can be very elusive mainly due to seeing conditions. They can be seen in a 4", usually I need an 8". Very often even my 16" fails to show them. Well worth experimenting with magnifications.


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#3 kfiscus

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Posted 12 January 2018 - 07:52 PM

E, and especially F, are useful challenges in rating a night's seeing conditions.  I don't get to see F very often here under the winter Jet Stream.  The stars of the Trapezium are ALL multiples, if I recall correctly.


Edited by kfiscus, 12 January 2018 - 07:54 PM.


#4 Carol L

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Posted 12 January 2018 - 08:01 PM

They can be very elusive mainly due to seeing conditions. They can be seen in a 4", usually I need an 8". Very often even my 16" fails to show them. Well worth experimenting with magnifications.

 

I've also had a difficult time with the 16" Dob, but sometimes they're fairly easy with the 8" SCT. If one pops in though, the other one can often be coaxed out of hiding. Patience can help, too - wait for a while, and the seeing might momentarily give you a 'wow' moment. LOVE IT when that happens! grin.gif 


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#5 Migwan

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Posted 12 January 2018 - 08:33 PM

Thanks much.  I think it must have been seeing.  The 8" had them in clearly down in TX on 2 different nights.  

 

That said, I was hoping it was because they were binaries.  Would have been more interesting.  Like watching Jupiter's moons from night to night

 

jd


Edited by Migwan, 12 January 2018 - 08:36 PM.


#6 SeaBee1

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Posted 12 January 2018 - 09:32 PM

I love looking at the Trap. I have seen the E star with my 4 inch frac, and that with averted vision. I can get the E and F with the 10 inch pretty regularly. The seeing has to be pretty bad for me to miss the E star. I have not gauged their magnitude change to detect eclipse.

 

gallery_241784_6798_159820.png

 

^^^ A sketch I did last February...

 

Keep looking up!

CB


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#7 BrooksObs

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Posted 13 January 2018 - 08:42 AM

I asked this in a thread in Observing but didn't get an answer so I'm dropping it in here. 

 

I caught both the E & F stars last February in Tx with my 2080.  Didn't know what to make of it as I wasn't aware of them before that.   I took a peek for them last week with my 1100 here MI and couldn't see them.  Seeing was fair and I expected to see them. (Though the seeing was not as good I had 3" of aperture.)

 

In the Sky&Telescope article that DLuders linked they state that these are binaries:

 

"They're both eclipsing binaries: V1016 Ori ranges from magnitude 6.7 to 7.7 over a period of 65 days and BM Ori from 7.9 to 8.7 every 6.5 days. With its much shorter period, it should be relatively easy to catch BM at both maximum and minimum sometime this season."

 

So I am wondering if it was poor seeing or do these stars sneak ought of sight???

 

jd

 

Hold on here, JD. I'm just a bit confused by your post, which starts out talking about the E and F stars in the Trapezium and then suddenly appears to shift to BM and V1016 ORI. To me, at least, it sounds as if you believe that the minute stars E and F are identical with the two variables...in spite of your stating that the variables are actually both relatively bright, obvious stars. V1016 ORI is, in fact, identical with Theta 1A ORI, the brightest star in the Trapezium, while BM ORI is star B in the Trapezium. Both are obvious targets with even the smallest telescopes. Now I don't have any idea of whether stars E and F are variable, but their placement among the vastly brighter members of the Trapezium, their decided faintness and the glowing background of the nebula, are usually most responsible for their elusiveness.

 

As to catching eclipses of BM ORI simply by chance, the odds of this are very unlikely. The eclipses take up only a quite limited fraction of the star's light curve, so witnessing the the star in eclipse usually requires both foreknowledge and careful planning. I know this to be true because I monitored several eclipses of BM in the past.

 

BrooksObs


Edited by BrooksObs, 13 January 2018 - 08:45 AM.


#8 Starman1

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Posted 13 January 2018 - 05:20 PM

I asked this in a thread in Observing but didn't get an answer so I'm dropping it in here. 

 

I caught both the E & F stars last February in Tx with my 2080.  Didn't know what to make of it as I wasn't aware of them before that.   I took a peek for them last week with my 1100 here MI and couldn't see them.  Seeing was fair and I expected to see them. (Though the seeing was not as good I had 3" of aperture.)

 

In the Sky&Telescope article that DLuders linked they state that these are binaries:

 

"They're both eclipsing binaries: V1016 Ori ranges from magnitude 6.7 to 7.7 over a period of 65 days and BM Ori from 7.9 to 8.7 every 6.5 days. With its much shorter period, it should be relatively easy to catch BM at both maximum and minimum sometime this season."

 

So I am wondering if it was poor seeing or do these stars sneak ought of sight???

 

jd

Poor seeing.

I've seen the G, H1, and I stars with the 12.5".

You should see the E & F stars all the time with 8" unless seeing is poor enough to obscure them.

See: http://www.skyandtel...ions-trapezium/


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#9 Migwan

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Posted 13 January 2018 - 07:42 PM

 

I asked this in a thread in Observing but didn't get an answer so I'm dropping it in here. 

 

I caught both the E & F stars last February in Tx with my 2080.  Didn't know what to make of it as I wasn't aware of them before that.   I took a peek for them last week with my 1100 here MI and couldn't see them.  Seeing was fair and I expected to see them. (Though the seeing was not as good I had 3" of aperture.)

 

In the Sky&Telescope article that DLuders linked they state that these are binaries:

 

"They're both eclipsing binaries: V1016 Ori ranges from magnitude 6.7 to 7.7 over a period of 65 days and BM Ori from 7.9 to 8.7 every 6.5 days. With its much shorter period, it should be relatively easy to catch BM at both maximum and minimum sometime this season."

 

So I am wondering if it was poor seeing or do these stars sneak ought of sight???

 

jd

 

Hold on here, JD. I'm just a bit confused by your post, which starts out talking about the E and F stars in the Trapezium and then suddenly appears to shift to BM and V1016 ORI. To me, at least, it sounds as if you believe that the minute stars E and F are identical with the two variables...in spite of your stating that the variables are actually both relatively bright, obvious stars. V1016 ORI is, in fact, identical with Theta 1A ORI, the brightest star in the Trapezium, while BM ORI is star B in the Trapezium. Both are obvious targets with even the smallest telescopes. Now I don't have any idea of whether stars E and F are variable, but their placement among the vastly brighter members of the Trapezium, their decided faintness and the glowing background of the nebula, are usually most responsible for their elusiveness.

 

As to catching eclipses of BM ORI simply by chance, the odds of this are very unlikely. The eclipses take up only a quite limited fraction of the star's light curve, so witnessing the the star in eclipse usually requires both foreknowledge and careful planning. I know this to be true because I monitored several eclipses of BM in the past.

 

BrooksObs

 


Cause I was confused, you think.  I read that part of the article quoted, incorrectly.  I have since reread. 

Because  I misread that part of the article.   Didn't catch where the author shifted from E & F to A & B. Here a more complete quote.  Must be getting whole sentence dyslexia. Sorry

 

" On nights of average seeing, four bright stars in the shape of a trapezoid give the bright quadruple star its name. But when the air settles down, a 6-inch scope magnifying 125× or higher will bring the fainter components E and F into view, turning the quartet into a sextet. Keep watch on components A and B at the narrow end of the figure. They're both eclipsing binaries: V1016 Ori ranges from magnitude 6.7 to 7.7 over a period of 65 days and BM Ori from 7.9 to 8.7 every 6.5 days. With its much shorter period, it should be relatively easy to catch BM at both maximum and minimum sometime this season."

Here is the link 

 

http://www.skyandtel...ions-trapezium/

 

jd


Edited by Migwan, 13 January 2018 - 07:46 PM.


#10 Migwan

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Posted 13 January 2018 - 07:58 PM

 

I asked this in a thread in Observing but didn't get an answer so I'm dropping it in here. 

 

I caught both the E & F stars last February in Tx with my 2080.  Didn't know what to make of it as I wasn't aware of them before that.   I took a peek for them last week with my 1100 here MI and couldn't see them.  Seeing was fair and I expected to see them. (Though the seeing was not as good I had 3" of aperture.)

 

In the Sky&Telescope article that DLuders linked they state that these are binaries:

 

"They're both eclipsing binaries: V1016 Ori ranges from magnitude 6.7 to 7.7 over a period of 65 days and BM Ori from 7.9 to 8.7 every 6.5 days. With its much shorter period, it should be relatively easy to catch BM at both maximum and minimum sometime this season."

 

So I am wondering if it was poor seeing or do these stars sneak ought of sight???

 

jd

Poor seeing.

I've seen the G, H1, and I stars with the 12.5".

You should see the E & F stars all the time with 8" unless seeing is poor enough to obscure them.

See: http://www.skyandtel...ions-trapezium/

 

I was thinking that  I saw some of the other stars, but I am not so sure now.  I used 170x, 240x  and  330x so I had plenty of mag.  Regretfully won't get another chance soon.

 

That is the article.

 

jd



#11 Asbytec

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Posted 13 January 2018 - 08:41 PM

I agree, the biggest hurdle to observing them is seeing and probably transparency. Some report seeing them in a 4" refractor, no doubt, and I can see them readily in a 6" aperture. Sometimes then sneak in and out due to seeing. One exceptionally clear and calm night, they couldn't sneak anywhere. They were tiny bright and steady pinpoints, it was a beautiful sight. 


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#12 Migwan

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Posted 14 January 2018 - 10:57 AM

It had to be seeing.  Was cloudy last night but cleared overnight.  I got the scope out of unheated pole barn at 430AM and was peeking at Jupiter just after 5AM.  The GRS was clearly visible and at 350x I could make out the banding on edge of the spot itself.  As sharp and as much contrast  as I have ever seen Jupiter. 

 

Mars, well I have done better.  Couldn't see any poles. 

 

Of course it was too late for the Trapezium to test for the E & F.  I hit M81 & 82 near zenith and the Cats Eye.  Not so good.  Not nearly as good as I have done from the yard on a clear night in the past.   

 

Checked collimation and it was good. Airy rings were not distinct in either 11" of 80ED.  ???  I think the clarity of the sky is deceiving me.   Looked clear and it was calm at ground level.

 

1*F  Dew point  -2*F   84% humidity  Oh well.  This morning was a bonus as it was not expected to clear up.

 

jd



#13 havasman

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Posted 14 January 2018 - 11:19 AM

See WDS 05353-0523, the Washington Double Star catalog listing for theta 1 Ori, for a pretty complete picture of the Trap stars. It's too lengthy and complex for my posting skills to put up in this post but the short of it is that there are MANY doubles defined.



#14 JimMo

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Posted 14 January 2018 - 01:07 PM

I admire your gumption JD, but it was too cold last night in Michigan for anything except sleeping under a warm blanket. Well, maybe I could think of one other thing, but I digress.     



#15 AstroDan2015

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Posted 14 January 2018 - 03:25 PM

2018.jpg Hi JD,

 

I was outside last night observing and M42 put on a great show through my 14" SCT equipped with an Orion Binoviewer. The Trapezium was a spectacular site, star B was very Mars like in color, more so than I can ever recall. Stars E and F were visible, seeing was excellent but too cold for imaging it, so here is a diagram and a HST image instead. The air temperature was 0* Fahrenheit but who cares, it's January in Wisconsin. Cheers, Dantrapezium_l.jpg


Edited by AstroDan2015, 14 January 2018 - 03:52 PM.

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