SECULAR AND STATISTICAL PARALLAX - Physics & Astronomycrenshaw/Secular_Statistical.pdfSecular...
Transcript of SECULAR AND STATISTICAL PARALLAX - Physics & Astronomycrenshaw/Secular_Statistical.pdfSecular...
SECULAR AND STATISTICAL PARALLAXCALEB ABBOTT
Our Journey Today:Basic Technique
Measurable Range
Potential Problems
Error
Examples in Literature
Step 1:
Pick stars that are likely to be the same distance away (type, luminosity, etc.)
To be able to make use of radial velocities, to determine relative Solar motion, the sample of stars needs to be randomly distributed around the sky.
Step 1:
Select a group of stars with common parameters
Obtain the Sun’s relative motion (radial velocities)
Step 2:
Determine the components of the star’s proper motion (𝜐 and 𝞃)
Requires position angle, declination, and the proper motion in both RA and Dec
Step 3:
Use statistics (“averages”) to get a mean parallax for stars in that group
Step 4:
Profit?
BASIC TECHNIQUESA STEP-BY-STEP GUIDE TO “SUCCESS” Turner, Odessa Astronomical Publications, vol. 25/1
(2012)
Step 2:
𝜐 and 𝞃 reflect on the Solar motion and the star’s spatial motion respectively
𝞃 should be randomly distributed
can be calculated with the RA and Dec Components of proper motion
BASIC TECHNIQUESA STEP-BY-STEP GUIDE TO “SUCCESS” Turner, Odessa Astronomical Publications, vol. 25/1
(2012)
Step 2: Determine components
Turner, Odessa Astronomical Publications, vol. 25/1 (2012)
Step 3: Calculate Parallax
Secular parallax —>
Better for when Solar motion dominates
Statistical parallax —>
Can obtain reasonable results out to ~500 pc
Turner, Odessa Astronomical Publications, vol. 25/1 (2012)
Bonney & Merrifield
Step 4: Profit Problems and Errors
Selecting stars likely to be near the same distance
Determining relative Solar motion
Measuring proper motions
Outdated?
Bonney & Merrifield
Hakkila (1990)
Used secular parallaxes to determine distances (and therefore absolute magnitudes) of Barium Stars.
Hakkila, Astrophysical Journal, Volume 100 Number 6 (1990)
HAKKILA (1990)PARALLAX OF BARIUM STARS Hakkila, Astrophysical Journal, Volume 100 Number 6
(1990)
J.H.J. de Bruijne et al (2000)
“A Hipparcos study of the Hyades open cluster”
Improved the distances provided by trig. parallax by ~3 times
Being that the proper motion is better constrained
de Bruijne et al, Astronomy and Astrophysics (2000)
J.H.J DE BRUIJNE (2000)IMPROVEMENTS TO THE PARALLAX de Bruijne et al, Astronomy and Astrophysics (2000)
THANK YOUQUESTIONS?