Reversed binaries in nearstars.stc

[ajtribick]

The following is a check on the various binary star systems in the first ~50% of nearstars.stc (down to 36 Oph).

Reversed orbits

These systems typically look correct from the perspective of the view of the sky-plane, but they are reversed in the radial direction.

Luhman 16

Reference: https://arxiv.org/pdf/1808.07835.pdf - table 6

In 2014, the radial velocity V_A - V_B is positive, implying that Luhman 16 A is receding faster than Luhman 16 B. In Celestia, this situation is reversed: Luhman 16 A is moving towards the Sun (-ve RV), Luhman 16 B is moving away

Sirius

Reference: https://arxiv.org/pdf/1809.01240.pdf - figure 9

At the current time, Sirius B should have a positive RV with respect to the system barycenter (i.e. receding). In Celestia, Sirius B is approaching the Sun.

Gliese 65

Reference: https://www.aanda.org/articles/aa/pdf/2016/09/aa28631-16.pdf - section 3.2

Measured V_B - V_A as positive on 2005-11-17, i.e. Gliese 65 B should be receding w.r.t. Gliese 65 A. In Celestia, Gliese 65 B is approaching the Sun, Gliese 65 A is receding.

Gliese 234

Reference: https://iopscience.iop.org/article/10.3847/1538-4365/ac7e57/pdf - figure 4

As shown on the RV diagram, the RV of Gliese 234 A at epoch 2456418 should be negative, i.e. approaching. Celestia shows this star as receding.

Gliese 229

Reference: https://iopscience.iop.org/article/10.3847/1538-3881/ac273e/pdf - figure 8

Radial velocity should be increasing from 2005 to 2020, in Celestia the radial velocity appears to be decreasing.

Correct orbits

As far as I can see, the following have the correct orbits in terms of radial velocities.

• ALF Cen AB
• Procyon AB
• Gliese 866 AB
• 70 Oph AB
• Gliese 570 BC

Undetermined

Could not check these, most cases due to insufficient RV data to distinguish between the two possible orientations that match the visual orbit.

• 61 Cyg
• Gliese 866 Aab
• Gliese 725
• Gliese 15
• EPS Ind BC
• SCR 1845-6357
• Gliese 860
• Gliese 473
• GJ 1245
• 40 Eri BC
• GJ 1116
• ETA Cas
• 36 Oph AB

[AstroChara]

So I did a little peek into this issue and it looks like Luhman 16's issue is just the erroneous mean anomaly (and for the other parameters, I arrived at slightly different values due to using position in Table 7). I haven't checked the other systems yet at this point.

[AstroChara]

Is this one done now?

[ajtribick]

I think so for now. Thanks!