The Sun

An infographic about the Sun published on the Big Bear Solar Observatory website

BBSO AO-308 Adaptive Optics

Adaptive optics (AO) is a technique that corrects in real time for image distortions caused by motions in the Earth’s atmosphere. The Big Bear Solar Observatory (BBSO) New Solar Telescope (NST) depends on a state-of-the-art AO system to enable diffraction-limited imaging (0.08 arc seconds in the visible). The current NST AO incorporates a Shack-Hartmann lens let array with 308 sub apertures for measuring wavefront error. The wavefront distortion is the corrected using a deformable mirror (DM) with 357 piezoelectric actuators.

AO systems, such as AO-308, can deliver diffraction-limited images over a relatively small angle on the sky known as isoplanatic patch. Image quality gradually deteriorates with increasing angle from the patch. The size of the patch varies with seeing conditions.

BBSO (Big Bear Solar Observatory)

The NST is configured as an off-axis Gregorian system consisting of a parabolic primary, prime focus field stop and heat reflector (heat-stop), elliptical secondary and diagonal flats. An off-axis design was chosen principally because of its vastly reduced stray light, since there is no central obscuration, which reduces the telescope’s MTF (Modulation Transfer Function) at high spatial frequency.

Umbral spikes in a large sunspot

A large sunspot observed on Sept 2, 2013 showing umbral flashes and spikes. The radially extending thin dark filaments seen against the light orange background are inflows of plasma into the sunspot. The small streaks of various length visible inside the sunspot against the dark orange background are the umbral spikes, which are oscillating jets driven by sunspot oscillations. 

NJIT

Groundbreaking images of the Sun captured by scientists at NJIT’s Big Bear Solar Observatory (BBSO) give a first-ever detailed view of the interior structure of umbrae – the dark patches in the center of sunspots – revealing dynamic magnetic fields responsible for the plumes of plasma that emerge as bright dots interrupting their darkness.