A review of astronomical science with visible light adaptive optics

Abstract

We review astronomical results in the visible (λ<1μm) with adaptive optics. Other than a brief period in the early 1990s, there has been little (<1 paper/yr) night-time astronomical science published with AO in the visible from 2000-2013 (outside of the solar or Space Surveillance Astronomy communities where visible AO is the norm, but not the topic of this invited review). However, since mid-2013 there has been a rapid increase visible AO with over 50 refereed science papers published in just ~2.5 years (visible AO is experiencing a rapid growth rate very similar to that of NIR AO science from 1997Close 2000). Currently the most productive small (D < 2 m) visible light AO telescope is the UV-LGS Robo-AO system (Baranec, et al. 2016) on the robotic Palomar D=1.5 m telescope (currently relocated to the Kitt Peak 1.8m; Salama et al. 2016). Robo-AO uniquely offers the ability to target >15 objects/hr, which has enabled large (>3000 discrete targets) companion star surveys and has resulted in 23 refereed science publications. The most productive large telescope visible AO system is the D=6.5m Magellan telescope AO system (MagAO). MagAO is an advanced Adaptive Secondary Mirror (ASM) AO system at the Magellan 6.5m in Chile ). This ASM secondary has 585 actuators with < 1 msec response times (0.7 ms typically). MagAO utilizes a 1 kHz pyramid wavefront sensor. The relatively small actuator pitch (~22 cm/subap) allows moderate Strehls to be obtained in the visible (0.63-1.05 microns). Long exposures (60s) achieve <30mas resolutions, 30% Strehls at 0.62 microns (r') with the VisAO camera in 0.5" seeing with bright R ≤ 9 mag stars. These capabilities have led to over 22 MagAO refereed science publications in the visible. The largest (D=8m) telescope to achieve regular visible AO science is SPHERE/ZIMPOL. ZIMPOL is a polarimeter fed by the ~1.2 kHz SPHERE ExAO system (Fusco et al. 2016). ZIMPOL's ability to differentiate scattered polarized light from starlight allows the sensitive detection of circumstellar disks, stellar surfaces, and envelopes of evolved AGB stars. Here we review the key steps to having good performance in the visible and review the exciting new AO visible science opportunities and science results in the fields of: exoplanet detection; circumstellar and protoplanetary disks; young stars; AGB stars; emission line jets; and stellar surfaces. The recent rapid increase in the scientific publications and power of visible AO is due to the maturity of the next-generation of AO systems and our new ability probe circumstellar regions with very high (10-30 mas) spatial resolutions that would otherwise require much larger (>10m) diameter telescopes in the infrared.

Optical turbulence forecast: ready for an operational application

“…The best seeing conditions guarantee the highest SR of an AO system and the most challenging scientific programs such as the search and the characterization of extra-solar planets would definitely gain from this condition. Besides we note that the selection of the temporal windows with excellent seeing will be even more critical for the adaptive optics in the visible (Close 2016) that is much more dependent on the conditions of the turbulence than the AO in the near-infrared. This new typology of adaptive optics represents the new frontier of ground-based observations.…”

A Design Study on Adaptive Primaries for 1-2 Meter Class Telescopes

“…12 Visible light AO systems have been in growing demand since 2013 and will be the only option for visible diffraction-limited observing after Hubble retires. 18 Major observatories are investing in instruments that can perform these corrections, including but not limited to, Subaru's SCExAO, 19 the MagAO-2k upgrade, 20 and LBT's SHARK-VIS. 21 This trend towards commissioning high-density actuator spacing AO systems is expected to continue in ELTclass (and larger) telescopes.…”

MagAO: status and science

“…A paper in this proceedings regarding cloud computing using MagAO/VisAO exoplanet data is "High-contrast imaging in the cloud with klipReduce and Findr" by Baltzell et al 24 Additionally, MagAO was used to help simulate the GMT phasing optics in this proceedings, "On-sky demonstration of the GMT dispersed fringe phasing sensor prototype on the Magellan Telescope" by Kopon et al 25 Finally, papers in this proceedings about the instrument include a paper describing our future MagAO upgrades and new instruments: "The path to visible extreme adaptive optics with MagAO" by Males et al 17 and a paper reviewing VisAO and other visible-light AO systems: "A Review of Astronomical Science with Visible Light Adaptive Optics" by Close. 26…”