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Posted: 11.07.2019, 05:21
by SpaceFanatic64
Enough, jujuapapa! Let's just get back on topic. :fie:

Posted: 11.07.2019, 05:23
by jujuapapa
Spacef… sorry mister ?, who are you ? :eh:

Posted: 11.07.2019, 05:25
by SpaceFanatic64
A user who does not want to use his real name. Now, I'm sorry for lashing out at you, but you start arguments too much. Please forgive me.

Posted: 18.07.2019, 15:22
by gironde
I just noticed that I miss the file gliesexindex.dat.
Can someone provide it to me?

:smile:

Posted: 19.07.2019, 01:48
by Sirius_Alpha
I don't seem to have that file, oddly enough.

Posted: 19.07.2019, 07:30
by gironde
It must exist somewhere where it has existed. I have the entry in the file celestia.cfg:
HDCrossIndex "catalogs/dat/hdxindex.dat"
SAOCrossIndex "catalogs/dat/saoxindex.dat"
GlieseCrossIndex "catalogs/dat/gliesexindex.dat"
(catalogs/ or data/ or …)
I only noticed yesterday that I was cleaning up my files.
Maybe it comes from the Celestia EPV3 version of the Russian site!

:sad:

Posted: 03.08.2019, 23:47
by nickroffical
hmm sound good!
Hmm, what exactly?
[moderator]

Posted: 12.08.2019, 23:13
by fyr02
thestias.PNG

Thestias/Pollux b

Posted: 01.04.2020, 01:25
by SevenSpheres
I guess one-off STCs might as well be posted here. LAMOST J040643.69+542347.8 is a rapidly rotating O-star that was recently discussed on the Discord; here's an STC file for it generated with the CelestiaWriter utility. The oblateness is calculated based on guesses about its mass and radius.

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"LAMOST J040643.69+542347.8" {
   RA 61.682058
   Dec 54.396626
   Distance 29033.75481
   AppMag 13.069
   SpectralType "O6.5V"
   Radius 7381204
   SemiAxes [ 1 0.521 1 ]
   UniformRotation {
      Period 23.8567245484029
   }
   InfoURL "https://arxiv.org/abs/2003.13891"
}


lamostj0406.png

Posted: 05.04.2020, 22:02
by SevenSpheres
A very close pair of white dwarfs that's recently been in the news; they can just be seen orbiting in real time! (This STC was originally posted by Sirius_Alpha.)

Code: Select all

Barycenter "SDSS J232230.20+050942.06"
{
   RA 350.625846
   Dec 5.161684
   Distance 2478.7856
   InfoURL "https://arxiv.org/abs/2004.00641"
}

"SDSS J232230.20+050942.06 A"
{
   OrbitBarycenter "SDSS J232230.20+050942.06"
   AppMag 12.5
   SpectralType "DA3"
   Radius 6500
   EllipticalOrbit
   {
      Period 3.81E-05
      SemiMajorAxis 0.000426
      Inclination 87.29837
      AscendingNode 288.094472
      ArgOfPericenter 294.640343
   }
   UniformRotation
   {
      Period 0.333722
      Inclination 87.29837
      AscendingNode 288.094472
   }
   InfoURL "https://arxiv.org/abs/2004.00641"
}

"SDSS J232230.20+050942.06 B"
{
   OrbitBarycenter "SDSS J232230.20+050942.06"
   AppMag 12.5
   SpectralType "DC6"
   Radius 6500
   EllipticalOrbit
   {
      Period 3.81E-05
      SemiMajorAxis 0.000479
      Inclination 87.29837
      AscendingNode 288.094472
      ArgOfPericenter 114.640343
   }
   UniformRotation
   {
      Period 0.333722
      Inclination 87.29837
      AscendingNode 288.094472
   }
   InfoURL "https://arxiv.org/abs/2004.00641"
}


This was my simple attempt at making a GIF of the system, it's actually 10x real time. (For some reason you need to click on the image to see the animation.) Maybe I'll try to make a better one later.

sdssgif.gif

Posted: 12.04.2020, 02:32
by LukeCEL
This add-on contains 57 rotating ellipsoidal variables in the LMC. The data is from Nie et al. (2017). (In case you're wondering, the 24 other systems will be in my LMC update.)

Spectral types for both stars have been estimated from the temperature. The temperature for the secondary is calculated from the radius and luminosity using the Stefan–Boltzmann law. For some stars, whose luminosity and/or radius are listed as "0.0" in the catalog, they have been estimated from the mass assuming a main-sequence star, or for a few systems, compact objects. Absolute magnitudes are estimated using the luminosity and radius.

The systems appear to have the correct inclination when viewed from the Earth, and should (hopefully) have correct conjunction times. A few systems are eccentric; for those systems the rotation might not be correct at all times, or at all. (I'm not an expert on rotation.)

(Edit: I have replaced the old file with a new file, that fixes a cruical error in two of the stars. Thank you to those who pointed this out!)
(Edit: I have again replaced the file. This fixes stars not being on the opposite sides of orbits. Thank you to Sirius_Alpha, who pointed this out.)

Enjoy:

Posted: 06.05.2020, 17:02
by SevenSpheres
Possible central star of the Soap Bubble Nebula (thanks to LukeCEL and Fafers_br for finding it):

Code: Select all

"Gaia DR2 2060926897208561280" {
   RA 303.83939324109
   Dec 38.04549843791
   #Distance 4180.7 # from parallax
   Distance 4900 # to match nebula
   AppMag 19.404 # from G+BP+RP mags
   SpectralType "sdO" # guess
}


HR 6819, the system with the new nearest black hole. I didn't include the outer companion star since there isn't an orbit for it. Since the black hole is non-accreting, no SSC file is needed. (Edit: added the radius of the black hole, I forgot to put it there before.)

Code: Select all

Barycenter 89605 "QV Tel:HR 6819" {
   RA 274.2813824693151
   Dec -56.0233576735714
   Distance 1119.021
}

"QV Tel Aa:HR 6819 Aa" {
   OrbitBarycenter "HR 6819"
   SpectralType "B3III"
   AppMag 5.36
   EllipticalOrbit {
      Epoch 24553177.44
      Period 0.110426
      SemiMajorAxis 0.220176 # mass ratio 5.0:4.2
      Eccentricity 0.03
      ArgOfPericenter 269
   }
}

"QV Tel Ab:HR 6819 Ab" {
   OrbitBarycenter "HR 6819"
   SpectralType "X"
   AbsMag 0
   Radius 12.39 # 4.2 solar masses
   EllipticalOrbit {
      Epoch 24553177.44
      Period 0.110426
      SemiMajorAxis 0.262115 # mass ratio 5.0:4.2
      Eccentricity 0.03
      ArgOfPericenter 89
   }
}

Posted: 06.05.2020, 18:57
by bluemoon
SevenSpheres wrote:HR 6819, the system with the new nearest black hole. I didn't include the outer companion star since there isn't an orbit for it. Since the black hole is non-accreting, no SSC file is needed. (Edit: added the radius of the black hole, I forgot to put it there before.)

Code: Select all

Barycenter 89605 "QV Tel:HR 6819" {
   RA 274.2813824693151
   Dec -56.0233576735714
   Distance 1119.021
}

"QV Tel Aa:HR 6819 Aa" {
   OrbitBarycenter "HR 6819"
   SpectralType "B3III"
   AppMag 5.36
   EllipticalOrbit {
      Epoch 24553177.44
      Period 0.110426
      SemiMajorAxis 0.220176 # mass ratio 5.0:4.2
      Eccentricity 0.03
      ArgOfPericenter 269
   }
}

"QV Tel Ab:HR 6819 Ab" {
   OrbitBarycenter "HR 6819"
   SpectralType "X"
   AbsMag 0
   Radius 12.39 # 4.2 solar masses
   EllipticalOrbit {
      Epoch 24553177.44
      Period 0.110426
      SemiMajorAxis 0.262115 # mass ratio 5.0:4.2
      Eccentricity 0.03
      ArgOfPericenter 89
   }
}

This system has 3 objects ! :eek:
Where is the third (the second star) ? :biggrin:

Posted: 06.05.2020, 19:00
by SevenSpheres
bluemoon wrote:This system has 3 objects !
Where is the third (the second star) ?

Did you read my post?

SevenSpheres wrote:I didn't include the outer companion star since there isn't an orbit for it.

If you take a look at the paper, it says "A classical Be star is in a wide orbit with an unconstrained period around an inner 40 d binary[...]" However, if you know of orbital parameters for the outer companion star they would be very much appreciated.

(You do remind me of a certain other user...)

Posted: 07.05.2020, 05:03
by jujuapapa
Why was bluemoon excluded by a guy present since 6 months ???
1. because he uses the same ip as me?
=> Normal, he is my son and he lives at home.
2. because his question was legitimate and disturbing?

In all cases give him his access ...

It sounds like an abuse of power!

And to come back to the question of my son: imagine Ford or GMC releasing a 3-wheel car instead of 4, what would be your reaction? :wink:
A council: wait to have all datas to publish something !

PS : if you delete members as quickly while the site is not very alive .... :eek: :fie:

Posted: 07.05.2020, 16:28
by SevenSpheres
jujuapapa, since you replied here I'll do the same. Banning bluemoon as a sockpuppet was not an action taken by me with no discussion, several members agreed with it on Discord (and it had nothing to do with the HR 6819 question). If bluemoon is your son, then this post is meatpuppetry, so the ban still stands.

For the sake of transparency this is what's being discussed:

sockpuppet.png

Posted: 19.06.2020, 01:27
by SevenSpheres
A compact, triple-eclipsing star system recently discovered by TESS.

Code: Select all

Barycenter "TIC 209409435" {
   RA 45.21625
   Dec -34.45707
   Distance 3095
}

Barycenter "TIC 209409435 AB" {
   OrbitBarycenter "TIC 209409435"
   EllipticalOrbit {
      Epoch 2458295.950
      Period 0.333668
      SemiMajorAxis 0.238257 # mass ratio (0.895+0.897):0.976
      Eccentricity 0.39653
      Inclination 73.50
      AscendingNode 47.64
      ArgOfPericenter 53.77
   }
}

"TIC 209409435 A" {
   OrbitBarycenter "TIC 209409435 AB"
   SpectralType "G2V" # guess from temperature
   AbsMag 5.15
   Temperature 5769
   Radius 606650
   EllipticalOrbit {
      Epoch 2458386.976
      Period 0.01565358
      SemiMajorAxis 0.038060 # mass ratio 0.895:0.897
      Eccentricity 0.00407
      Inclination 73.71
      AscendingNode 47.67
      ArgOfPericenter 12.94
   }
}

"TIC 209409435 B" {
   OrbitBarycenter "TIC 209409435 AB"
   SpectralType "G2V" # guess from temperature
   AbsMag 5.13
   Temperature 5779
   Radius 608738
   EllipticalOrbit {
      Epoch 2458386.976
      Period 0.01565358
      SemiMajorAxis 0.037975 # mass ratio 0.895:0.897
      Eccentricity 0.00407
      Inclination 73.71
      AscendingNode 47.67
      ArgOfPericenter 192.94
   }
}

"TIC 209409435 C" {
   OrbitBarycenter "TIC 209409435"
   SpectralType "F9V" # guess from temperature
   AbsMag 4.54
   Temperature 6074
   Radius 714484
   EllipticalOrbit {
      Epoch 2458295.950
      Period 0.333668
      SemiMajorAxis 0.437456 # mass ratio (0.895+0.897):0.976
      Eccentricity 0.39653
      Inclination 73.50
      AscendingNode 47.64
      ArgOfPericenter 233.77
   }
}

Posted: 21.06.2020, 05:02
by jujuapapa
Here is the result...

TIC2094.jpg

Posted: 22.06.2020, 03:48
by LukeCEL
Regarding the QV Tel/HR 6819 system: another recent study found an alternative explanation that invokes only two stars (and no black hole).

https://arxiv.org/abs/2006.10770

Posted: 23.06.2020, 01:33
by LukeCEL
We're getting more papers about HR 6819.

https://arxiv.org/abs/2006.11974 - This paper suggests a similar model to the one mentioned above.

https://arxiv.org/abs/2006.11872 - This paper suggests that HR 6819 is a black hole binary, but the Be star is actually a chance alignment.