Gravitational Lensing By A Star Outside Our Solar System

Interesting article, Thank You!

I briefly wondered if this phenomena might significantly alter nearby star distance measurements through parallax analysis but then I recognized this gravitational lensing effect had to be a secondary or tertiary effect. Particularly since it took Hubbel's resolution and long lifetime of data to reveal this lensing effect.

In their graphic they show deflection at only one instant, but the distant star's apparent position follows a loop-shaped path as the white dwarf moves past.

Thanks both to Bayes for the OP, and to you for this. It really threw me for a loop!

Back of my envelope suggests that the angle of deviation (2 milliarcseconds) is more like the angle subtended by a human hair 1,600 miles away.

Caveat: my envelope is a bit crumpled. Anyone else want to waste a bit of Friday time and run the sums? (PS I've taken a hairwidth as 0.07mm).

....thickness could be somewhere between 17 um for flaxen to 181 um for black...but 70 um is a good average....but I don't want to split hairs.....

My back-of-the-envelope agrees. I get ~65 microns (70 microns for the average diameter of a human hair).

Conversely, if the target is the diameter of a U.S. quarter (0.955 inches), the distance comes out to be ~560,000 miles, or resolve an object 0.4 inches in diameter on the Moon's surface.

Interestingly, the HST's angular resolution is around 50 milli-arcseconds, 25 times worse, so I'm wondering how they wrangled 2 milli-arcseconds out of this.

Something's amiss.

The diameter of a U.S. quarter as viewed from 1500 miles subtends an angle of 746 mas (milli-arcseconds).

I get the width of a quarter ( ~ 1 inch) at about 2 milliarcseconds at 1500 miles, just like the article says.

angle = (57 deg * 3600 arcsec/deg)/(1500 mi * 5280 ft/mi * 12 in/ft) = .0022 arcsec

You're right.

I can't do math anymore. I used to be so good at it too

You're right. Pulled my envelope out of the bin and found a wrinkle just about where I was doing a conversion of angles, resulting in my answer being out by a factor of 360. 0.07mm (width of hair) × 360 = 25.2mm, which is very close to 1".

It still bothers me wondering how they can achieve that kind of accuracy from a platform in orbit.

Orbit means freedom from seismological and atmospheric interference.

Orbit means freedom from seismological and atmospheric interference.

At least unmanned platforms. A manned telescope would be useless. Every time someone moved, it would be out of alignment!

According to space.com:

"Measuring such a subtle change required a powerful instrument, like the Hubble telescope's high-resolution camera, which was installed in 2009."

https://www.space.com/37113-einstein-relativity-experiment-measures-star-mass.html

The pixel resolution of the WFC3 is 40 milliarcseconds:

https://en.wikipedia.org/wiki/Wide_Field_Camera_3

Sub-pixel resolution is not difficult to achieve for a high signal-to-noise signal like a star image with a bit of signal processing.

https://en.wikipedia.org/wiki/Sub-pixel_resolution