1 / 11

Calculating Escape Velocities on 75,000 Double Star Systems Using Gaia Data Release 2

Calculating Escape Velocities on 75,000 Double Star Systems Using Gaia Data Release 2. By Tol Wassman, Zachary Haarz, Morgan Watts, Jake North, and Kalée Tock. Double Stars. Close together Confirm orbits & find mass Washington Double Star catalogue (WDS) tracks these stars

lindseyp
Download Presentation

Calculating Escape Velocities on 75,000 Double Star Systems Using Gaia Data Release 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Calculating Escape Velocities on 75,000 Double Star Systems Using Gaia Data Release 2 By Tol Wassman, Zachary Haarz, Morgan Watts, Jake North, and Kalée Tock

  2. Double Stars • Close together • Confirm orbits & find mass • Washington Double Star catalogue (WDS) tracks these stars • Gaia improves our ability to tell binaries from optical doubles

  3. Binary Stars • Same distance from Earth: parallax (Plx) • Moving together in space: Proper Motion (PM), radial velocity (RV) • Relative motion less than escape velocity (vesc)

  4. Richard Harshaw’s Data • Previous paper, also using Gaia data • Used parallax data, relative radial velocity, fit to R^2, and proper motion • Many stars did not have Gaia data • Created a spreadsheet with the scores

  5. Matching WDS and Gaia • Query Gaia around WDS coordinates • Guess and check: • Magnitude within 2 • PA within 3o • Sep within 1’’ • Algorithm: • Closer to WDS, better • Also PM, Dist to precise search coordinates wherever possible • Ideally obtain PMs, RVs, Lum/Mag, and Plxs

  6. Separation

  7. Velocities • Escape velocity needs mass, which needs luminosity, sometimes needs mag and plx • R is pythagorean theorem with tangential and radial separation • Relative velocity needs speeds which need Plx, PM, and RV

  8. Z factor • Z = Escape velocity/relative velocity • Z > 1.5 will be binary, Z < 0.5 will be optical • Simple range of 1.5 to 0.5 is nuanced range - looks best as Z - 0.5

  9. Results • Harshaw sorts stars without parallax, Z-Factor ignores them • 68.5% optical doubles using Z-factor, and 16% using Harshaw’s method • Large difference in stars considered physical, considering omissions

  10. Notes For Future Research • Small percent in between, binaries grow harsher over time? • Use orbital state vectors to determine theoretical orbits for binaries • Identify a more general stellar mass formula or refine the current one

  11. Categories

More Related