26 research outputs found
Status of MagAO and review of astronomical science with visible light adaptive optics
We review astronomical results in the visible (lambda <1 micron) with
adaptive optics and note the status the MagAO system and the recent upgrade to
visible camera's Simultaneous/Spectra Differential Imager (SDI to SDI+) mode.
Since mid-2013 there has been a rapid increase visible AO with over 50 refereed
science papers published in just 2015-2016 timeframe. The main focus of this
paper is another large (D=6.5m Magellan telescope) AO system (MagAO) which has
been very productive in the visible (particularly at the H-alpha emission
line). MagAO is an advanced Adaptive Secondary Mirror (ASM) AO system at the
Magellan 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
(PWFS). The relatively small actuator pitch (~22 cm/subap, 300 modes, upgraded
to 30 pix dia. PWFS) allows moderate Strehls to be obtained in the visible
(0.63-1.05 microns). Long exposures (60s) achieve <30mas resolutions and 30%
Strehls at 0.62 microns (r') with the VisAO camera (0.5-1.0 microns) in 0.5"
seeing with bright R < 9 mag stars (~10% Strehls can be obtained on fainter
R~12 mag guide stars). Differential Spectral Imaging (SDI) at H-alpha has been
very important for accreting exoplanet detection. There is also a 1-5micron
science camera (Clio; Morzinski et al. 2016). These capabilities have led to
over 35 MagAO refereed science publications. 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. 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.Comment: 18 pages, Proc. SPIE 10703, Adaptive Optics IV, June 2018 Austin TX.
arXiv admin note: substantial text overlap with arXiv:1407.509
The Gray Needle: Large Grains in the HD 15115 Debris Disk from LBT/PISCES/Ks and LBTI/LMIRcam/L' Adaptive Optics Imaging
We present diffraction-limited \ks band and \lprime adaptive optics images of
the edge-on debris disk around the nearby F2 star HD 15115, obtained with a
single 8.4 m primary mirror at the Large Binocular Telescope. At \ks band the
disk is detected at signal-to-noise per resolution element (SNRE) \about 3-8
from \about 1-2\fasec 5 (45-113 AU) on the western side, and from \about
1.2-2\fasec 1 (63-90 AU) on the east. At \lprime the disk is detected at SNRE
\about 2.5 from \about 1-1\fasec 45 (45-90 AU) on both sides, implying more
symmetric disk structure at 3.8 \microns . At both wavelengths the disk has a
bow-like shape and is offset from the star to the north by a few AU. A surface
brightness asymmetry exists between the two sides of the disk at \ks band, but
not at \lprime . The surface brightness at \ks band declines inside 1\asec
(\about 45 AU), which may be indicative of a gap in the disk near 1\asec. The
\ks - \lprime disk color, after removal of the stellar color, is mostly grey
for both sides of the disk. This suggests that scattered light is coming from
large dust grains, with 3-10 \microns -sized grains on the east side and 1-10
\microns dust grains on the west. This may suggest that the west side is
composed of smaller dust grains than the east side, which would support the
interpretation that the disk is being dynamically affected by interactions with
the local interstellar medium.Comment: Apj-accepted March 27 2012; minor correction
The Peculiar Debris Disk of HD 111520 as Resolved by the Gemini Planet Imager
Using the Gemini Planet Imager (GPI), we have resolved the circumstellar
debris disk around HD 111520 at a projected range of ~30-100 AU in both total
and polarized -band intensity. The disk is seen edge-on at a position angle
of ~165 along the spine of emission. A slight inclination or
asymmetric warping are covariant and alters the interpretation of the observed
disk emission. We employ 3 point spread function (PSF) subtraction methods to
reduce the stellar glare and instrumental artifacts to confirm that there is a
roughly 2:1 brightness asymmetry between the NW and SE extension. This specific
feature makes HD 111520 the most extreme examples of asymmetric debris disks
observed in scattered light among similar highly inclined systems, such as HD
15115 and HD 106906. We further identify a tentative localized brightness
enhancement and scale height enhancement associated with the disk at ~40 AU
away from the star on the SE extension. We also find that the fractional
polarization rises from 10 to 40% from 0.5" to 0.8" from the star. The
combination of large brightness asymmetry and symmetric polarization fraction
leads us to believe that an azimuthal dust density variation is causing the
observed asymmetry.Comment: 9 pages, 8 Figures, 1 table, Accepted to Ap
Astro2020 APC White Paper: The Early Career Perspective on the Coming Decade, Astrophysics Career Paths, and the Decadal Survey Process
In response to the need for the Astro2020 Decadal Survey to explicitly engage
early career astronomers, the National Academies of Sciences, Engineering, and
Medicine hosted the Early Career Astronomer and Astrophysicist Focus Session
(ECFS) on October 8-9, 2018 under the auspices of Committee of Astronomy and
Astrophysics. The meeting was attended by fifty six pre-tenure faculty,
research scientists, postdoctoral scholars, and senior graduate students, as
well as eight former decadal survey committee members, who acted as
facilitators. The event was designed to educate early career astronomers about
the decadal survey process, to solicit their feedback on the role that early
career astronomers should play in Astro2020, and to provide a forum for the
discussion of a wide range of topics regarding the astrophysics career path.
This white paper presents highlights and themes that emerged during two days
of discussion. In Section 1, we discuss concerns that emerged regarding the
coming decade and the astrophysics career path, as well as specific
recommendations from participants regarding how to address them. We have
organized these concerns and suggestions into five broad themes. These include
(sequentially): (1) adequately training astronomers in the statistical and
computational techniques necessary in an era of "big data", (2) responses to
the growth of collaborations and telescopes, (3) concerns about the adequacy of
graduate and postdoctoral training, (4) the need for improvements in equity and
inclusion in astronomy, and (5) smoothing and facilitating transitions between
early career stages. Section 2 is focused on ideas regarding the decadal survey
itself, including: incorporating early career voices, ensuring diverse input
from a variety of stakeholders, and successfully and broadly disseminating the
results of the survey
Protoplanetary Disk Science Enabled by Extremely Large Telescopes
The processes that transform gas and dust in circumstellar disks into diverse exoplanets remain poorly understood. One key pathway is to study exoplanets as they form in their young (∼few~Myr) natal disks. Extremely Large Telescopes (ELTs) such as GMT, TMT, or ELT, can be used to establish the initial chemical conditions, locations, and timescales of planet formation, via (1)~measuring the physical and chemical conditions in protoplanetary disks using infrared spectroscopy and (2)~studying planet-disk interactions using imaging and spectro-astrometry. Our current knowledge is based on a limited sample of targets, representing the brightest, most extreme cases, and thus almost certainly represents an incomplete understanding. ELTs will play a transformational role in this arena, thanks to the high spatial and spectral resolution data they will deliver. We recommend a key science program to conduct a volume-limited survey of high-resolution spectroscopy and high-contrast imaging of the nearest protoplanetary disks that would result in an unbiased, holistic picture of planet formation as it occurs
The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Final Report
The Habitable Exoplanet Observatory, or HabEx, has been designed to be the Great Observatory of the 2030s. For the first time in human history, technologies have matured sufficiently to enable an affordable space-based telescope mission capable of discovering and characterizing Earthlike planets orbiting nearby bright sunlike stars in order to search for signs of habitability and biosignatures. Such a mission can also be equipped with instrumentation that will enable broad and exciting general astrophysics and planetary science not possible from current or planned facilities. HabEx is a space telescope with unique imaging and multi-object spectroscopic capabilities at wavelengths ranging from ultraviolet (UV) to near-IR. These capabilities allow for a broad suite of compelling science that cuts across the entire NASA astrophysics portfolio. HabEx has three primary science goals: (1) Seek out nearby worlds and explore their habitability; (2) Map out nearby planetary systems and understand the diversity of the worlds they contain; (3) Enable new explorations of astrophysical systems from our own solar system to external galaxies by extending our reach in the UV through near-IR. This Great Observatory science will be selected through a competed GO program, and will account for about 50% of the HabEx primary mission. The preferred HabEx architecture is a 4m, monolithic, off-axis telescope that is diffraction-limited at 0.4 microns and is in an L2 orbit. HabEx employs two starlight suppression systems: a coronagraph and a starshade, each with their own dedicated instrument
The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Final Report
The Habitable Exoplanet Observatory, or HabEx, has been designed to be the
Great Observatory of the 2030s. For the first time in human history,
technologies have matured sufficiently to enable an affordable space-based
telescope mission capable of discovering and characterizing Earthlike planets
orbiting nearby bright sunlike stars in order to search for signs of
habitability and biosignatures. Such a mission can also be equipped with
instrumentation that will enable broad and exciting general astrophysics and
planetary science not possible from current or planned facilities. HabEx is a
space telescope with unique imaging and multi-object spectroscopic capabilities
at wavelengths ranging from ultraviolet (UV) to near-IR. These capabilities
allow for a broad suite of compelling science that cuts across the entire NASA
astrophysics portfolio. HabEx has three primary science goals: (1) Seek out
nearby worlds and explore their habitability; (2) Map out nearby planetary
systems and understand the diversity of the worlds they contain; (3) Enable new
explorations of astrophysical systems from our own solar system to external
galaxies by extending our reach in the UV through near-IR. This Great
Observatory science will be selected through a competed GO program, and will
account for about 50% of the HabEx primary mission. The preferred HabEx
architecture is a 4m, monolithic, off-axis telescope that is
diffraction-limited at 0.4 microns and is in an L2 orbit. HabEx employs two
starlight suppression systems: a coronagraph and a starshade, each with their
own dedicated instrument.Comment: Full report: 498 pages. Executive Summary: 14 pages. More information
about HabEx can be found here: https://www.jpl.nasa.gov/habex