Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

40 Eridani

  • Please log in to reply
19 replies to this topic

#1 tchandler

tchandler

    Mercury-Atlas

  • *****
  • topic starter
  • Posts: 2,758
  • Joined: 07 Aug 2014

Posted 24 October 2019 - 09:15 PM

Last year I observed this, the most fascinating triple star of them all. The two brighter components were easy but I’m not sure I glimpsed the faintest member.

 

40 Eri consists of three dwarf stars.

 

1. 40 Eri A: mag 4.42 dwarf solar type star. One of the few in the sky that are naked eye.

2. 40 Eri B: mag 9.72 white dwarf. One of the easiest white dwarfs visible in the sky.

3. 40 Eri C: mag 11.2 red dwarf.

 

The A-B and B-C distances are 83” and 9”, and incidentally the latter is near its maximum separation.

 

Going to use as much magnification as possible. Using 11” Teeter dob f/4.5.

 

Sky conditions fairly dark - bortle 3-4. Will have to wait until after midnight tho, and so close to Halloween. Spooky.
 

 


  • payner, R Botero, eros312 and 3 others like this

#2 chrysalis

chrysalis

    ISS

  • *****
  • Posts: 22,723
  • Joined: 10 Aug 2013
  • Loc: North Central NC

Posted 25 October 2019 - 09:37 AM

Will look for this one next time!



#3 ssmith

ssmith

    Viking 1

  • *****
  • Posts: 823
  • Joined: 28 Jun 2012
  • Loc: Colorado

Posted 25 October 2019 - 01:44 PM

This system is the home of Star Treks' Mr Spock and quickly becomes a favorite of anyone who views it.

 

Here is a link to a previous thread.


Edited by ssmith, 25 October 2019 - 01:52 PM.

  • tchandler, flt158, Far Star and 1 other like this

#4 tchandler

tchandler

    Mercury-Atlas

  • *****
  • topic starter
  • Posts: 2,758
  • Joined: 07 Aug 2014

Posted 27 October 2019 - 07:54 AM

Jim Kaler has an entertaining and informative write up as well about Keid, Omicron 2, or 40 Eridani.


  • c2m2t likes this

#5 Waddensky

Waddensky

    Messenger

  • -----
  • Vendors
  • Posts: 478
  • Joined: 18 Sep 2017
  • Loc: The Netherlands

Posted 27 October 2019 - 08:09 AM

Thanks, I really need to revisit this enigmatic triplet soon. B is much dimmer than Sirius B but evidently a lot easier to observe. Indeed a nice opportunity for those who wish to see a white dwarf with modest equipment!
  • tchandler and Tyson M like this

#6 gfeulner

gfeulner

    Viking 1

  • *****
  • Posts: 942
  • Joined: 23 Nov 2007
  • Loc: Bergen county, New Jersey

Posted 12 January 2020 - 11:10 PM

I observed this beautiful triplet tonight with my 140mm refractor. The sky was hazy but the C companion was visible.

Gerry


  • tchandler and flt158 like this

#7 c2m2t

c2m2t

    Ranger 4

  • -----
  • Posts: 324
  • Joined: 03 Oct 2017
  • Loc: Pembroke, Ont.

Posted 13 January 2020 - 05:45 PM

Hi All!

I was surprised to discover that this system has actually 5 components. D & E were added in 1850 as part of a proper motion study. I did check my own image archive and with a bit of stretching, I think both D & E at mags 12.62 and 12.99 are resolved. I have not added the image here, suspecting that the reduced file size would render D & E a washout. But for the heck of it and prior to the  knowledge of the high proper motion of D & E, I consulted Aladin to locate this pair using the distance tool. Needless to say the most recent positional data 1998 provided positions that did not coincide with what I figured were D & E. Two stars having what appears to be the correct magnitudes were close so I figured something was up. 

 

At this point I have to admit my lack of knowledge in manipulating the proper motion tools within VizieR so I went about it the old fashioned way...plotted D & E positions for 1850 and 1998 based on the first and last separation and PA data, available in the WDS/Stelle Doppie. This I have plotted on the image and drawn a line indicating the proper motion/direction for both D & E. WOW!! Right away one could be very easily persuaded that D & E are physically bound. Trajectories through space look identical. For the "halibut", I used the distance tool in Aladin to calculate the angle and distance for the two trajectories. They are oh so close. Angle and distance are as follows:

 

line D-D  34 degrees, 9.994 minutes

line E-E  33 degrees, 9.988 minutes

 

This pretty much tells the story...but given that no-one has identified this pair after all the detail searches of the new GAIA data, this pair may have significantly different trajectories perpendicular to our field of view. In any case...an interesting possibility.

 

Cheers, Chris.

 

 

Attached Thumbnails

  • STF 518-5247-CN-ID-2.JPG

  • Inkswitch and eros312 like this

#8 ssmith

ssmith

    Viking 1

  • *****
  • Posts: 823
  • Joined: 28 Jun 2012
  • Loc: Colorado

Posted 13 January 2020 - 07:05 PM

Hi Chris -

 

The GAIA data shows that D & E certainly have no physical relationship to 40 Eridani and also that they have no relationship to one another.

Their proper motions are radically different and they are separated by over 1,000 Ly.

 

40 Eri D-E Aladin 1.jpg

 

 


Edited by ssmith, 13 January 2020 - 08:04 PM.

  • Tyson M likes this

#9 c2m2t

c2m2t

    Ranger 4

  • -----
  • Posts: 324
  • Joined: 03 Oct 2017
  • Loc: Pembroke, Ont.

Posted 13 January 2020 - 08:13 PM

Hi Steve!

Happy New Year by the way! Thanks for that? I suspected as much but it was still an interesting study? 

Where would we be without these satellite surveys!smile.gif

 

Cheers, Chris.



#10 dmdouglass

dmdouglass

    Surveyor 1

  • *****
  • Posts: 1,933
  • Joined: 23 Dec 2007
  • Loc: Tempe, AZ

Posted 13 January 2020 - 09:00 PM

This target "Keid", or STF 0518 is another of the targets in the AL Multiple Star Program. I imaged this target on Dec 15....  

 

STF-0518-DS-20191215.jpg


  • eros312 likes this

#11 Far Star

Far Star

    Ranger 4

  • *****
  • Posts: 345
  • Joined: 02 Sep 2014
  • Loc: Germany

Posted 15 January 2020 - 04:33 AM

40 Eridani

 

Photo taken on 12/30/2019 with Canon EOS 800D, Takahashi FC-100DL (100/900 mm) and 1.6x Barlow, ISO 6400, 1 second exposure time

 

In 2018, a planet was discovered orbiting 40 Eridani A with a minimum mass of 8.47±0.47 Earth masses. Contrary to what many media said, this planet could not be Mr. Spock's fictional home planet "Vulcan" because it orbits its host star outside the habitable zone. The planet has an orbital period of 42 days and is considerably interior to the habitable zone - that is, too close to 40 Eridani A for habitability. It receives 9 to 10 times more sunlight than Earth, about five times that of Venus and more than Mercury.

 

https://www.geekwire...er-earth-spock/  (See "Update for 5:25 p.m. PT Sept. 26")

 

https://en.wikipedia...wiki/40_Eridani

 

Greetings from Upper Bavaria,

 

Ulrich

Attached Thumbnails

  • Ausschnitt-05-beschriftet.jpg

Edited by Far Star, 15 January 2020 - 04:55 AM.

  • payner, gfeulner, dmdouglass and 7 others like this

#12 fred1871

fred1871

    Surveyor 1

  • -----
  • Posts: 1,647
  • Joined: 22 Mar 2009
  • Loc: Australia

Posted 15 January 2020 - 08:05 AM

Nicely imaged, Ulrich. Good scale, and enough exposure for both the lesser stars.

 

I've seen both companions easily with an 18cm refractor, and there are reports of seeing them both with 10cm. The separation is quite wide, as the photo shows - it's mainly a matter of light-gathering to reach the mag 11.5 dimmer C star.


  • Far Star likes this

#13 Uwe Pilz

Uwe Pilz

    Gemini

  • *****
  • Moderators
  • Posts: 3,113
  • Joined: 16 May 2008
  • Loc: Leipzig, Germany

Posted 20 January 2020 - 02:58 PM

Thank you for pointing at this interesting multiple. This night the air was clear and more ore less steady. I tried what I could detect with my 4 inch refractor. A and B were easy, I could see them at 144x. At 288x I could get a glimpse of C. This required A being outside of the filed of view.

 

My sketch is mirror reversed.

Attached Thumbnails

  • 200120_40Eri.jpg

  • gfeulner, tchandler, flt158 and 1 other like this

#14 tchandler

tchandler

    Mercury-Atlas

  • *****
  • topic starter
  • Posts: 2,758
  • Joined: 07 Aug 2014

Posted 24 January 2020 - 06:28 PM

Very nice photo - and thanks for the links too Ulrich. The so-called super Earth sounds more like a super Mercury.

 

According to Jim Kaler, the  mass of the white dwarf when it was hydrogen-fusing is thought to have been around one solar. 40 Eridani B is not what the Sun will not be.

 

Thanks for sharing your sketch Uwe. I’m looking forward to seeing the trio again soon. 


  • Far Star likes this

#15 chrysalis

chrysalis

    ISS

  • *****
  • Posts: 22,723
  • Joined: 10 Aug 2013
  • Loc: North Central NC

Posted 26 January 2020 - 06:50 AM

Will look for this one next time!

Finally got out last night and guess what? I totally forgot foreheadslap.gif   !!



#16 SeaBee1

SeaBee1

    Skylab

  • *****
  • Posts: 4,157
  • Joined: 19 Mar 2015
  • Loc: Under the DFW light barrier

Posted 26 January 2020 - 12:46 PM

Interesting that this system has been brought up a couple of times on these forums. I actually saw this system mentioned in another thread and then saw this one. I am at work right now (on my break...) and though my skies are pretty iffy at the moment, I hope to have some clearing by this evening. And if not tonight, maybe tomorrow night, I can try for this one. Thanks all for the interesting observations!

 

Good hunting!

 

CB


  • tchandler likes this

#17 ssmith

ssmith

    Viking 1

  • *****
  • Posts: 823
  • Joined: 28 Jun 2012
  • Loc: Colorado

Posted 29 January 2020 - 07:14 PM

Here is a photo taken last night through my C9.  5 frames stacked.

 

40 Eri C9 1-28-20 avg 5fr.jpg

 


  • payner, dmdouglass, chrysalis and 6 others like this

#18 SeaBee1

SeaBee1

    Skylab

  • *****
  • Posts: 4,157
  • Joined: 19 Mar 2015
  • Loc: Under the DFW light barrier

Posted 30 January 2020 - 09:20 AM

Interesting that this system has been brought up a couple of times on these forums. I actually saw this system mentioned in another thread and then saw this one. I am at work right now (on my break...) and though my skies are pretty iffy at the moment, I hope to have some clearing by this evening. And if not tonight, maybe tomorrow night, I can try for this one. Thanks all for the interesting observations!

 

Good hunting!

 

CB

 

Well, it didn't happen for me, work, weather, and wife interferences... my next opportunity is a little over a week away... *sigh*...

 

Keep looking up!

 

CB



#19 cloudbuster

cloudbuster

    Viking 1

  • *****
  • Posts: 856
  • Joined: 02 Feb 2016
  • Loc: Almere, The Netherlands

Posted 05 February 2020 - 02:57 PM

Here's my sketch of the triple. Thanks for the reminder to observe this one! I would have forgotten otherwise...

Above the city lights and with the moon nearby the star system was still easily found and seen, although C appeared really faint. A is very bright and shows a yellow, almost orange hue. B is much dimmer, but still a blue (violet) color was sensed. Some other dimmer stars could be found in the FOV, but they were all dimmer than the three, except for one. Seeing was quite bad, also due to the low altitude, but the separation of B and C was evident nonetheless. A did not show a pinpoint star.

 

40 Eri.jpg

 

Regards, Martijn


Edited by cloudbuster, 05 February 2020 - 02:59 PM.

  • Pete W, tchandler, Far Star and 1 other like this

#20 tchandler

tchandler

    Mercury-Atlas

  • *****
  • topic starter
  • Posts: 2,758
  • Joined: 07 Aug 2014

Posted 05 February 2020 - 06:42 PM

That’s a mighty fine sketch. Thanks.




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics