Podcasts about Adaptive optics

In this episode, my guest is Dr. Brian Keating, Ph.D., a cosmologist and professor of physics at the University of California, San Diego. We discuss the origins of the universe and how humans have used light and optics to understand where and how life on Earth emerged. We explore how early humans charted the stars, sun, moon, and other celestial events to measure time and track seasons, as well as how stargazing continues to connect us to a shared ancient experience. Additionally, we examine the scientific process, the practical and ethical challenges of pursuing groundbreaking discoveries, and the emotional toll of striving for recognition in one's profession. Finally, we discuss whether astrology has any scientific validity and consider the possibility of life beyond Earth. Read the full episode show notes at hubermanlab.com. Thank you to our sponsors AG1: https://drinkag1.com/huberman LMNT: https://drinklmnt.com/huberman BetterHelp: https://betterhelp.com/huberman Function: https://functionhealth.com/huberman Helix Sleep: https://helixsleep.com/huberman ROKA: https://roka.com/huberman Timestamps 00:00:00 Dr. Brian Keating 00:02:07 Cosmology, Origin of Universe 00:05:41 Sponsors: LMNT & BetterHelp 00:08:33 Stars, Planets, Early Humans, Time 00:14:53 Astrology, Ophiuchus Constellation 00:19:58 Pineal Gland, Time-Keeping & Stars, Seasons & Offspring 00:29:19 Humans, Time Perception, Astronomy 00:36:08 Sponsor: AG1 00:37:47 Brain & Prediction; Moonset, Syzygy; Telescope, Galileo  00:46:36 Light Refraction; Telescope, Eyeglasses 00:51:36 Earth Rotation & Sun 00:53:43 Glass, Microscope, Telescopes & Discovery 01:02:53 Science as Safe Space; Jupiter, Galileo, Discovery, Time 01:10:48 Early Humans, Stonehenge, Pyramids, Measurement Standards  01:15:54 Giants of Astronomy  01:20:04 Sponsors: Function & Helix Sleep 01:23:10 Origin of Life, Scientific Method & P-Hacking; Nobel Prize, Big Bang, Inflation 01:30:20 Cosmic Microwave Background Radiation, BICEP 01:37:58 Father & Son Relationship, Science & Rewards 01:44:06 Loss, Mentor  01:49:55 Antarctica, South Pole 01:56:49 Light & Heat Pollution, South Pole 02:01:09 Prize Pursuit, First Discovery; Star Collapse, Micrometeorites, Polarization  02:08:26 Sponsor: ROKA 02:10:08 Moon, Size & Horizon; Visual Acuity; Rainbow or Moon Bigger? 02:15:21 Sunset, Green Flash, Color Opponency 02:23:05 Menstrual & Lunar Cycles; Moon Movement 02:26:36 Northern Hemisphere & Stargazing, Dark Sky Communities, Telescope 02:29:51 Constellations, Asterism; Halley's & Hale-Bopp Comets 02:32:13 Navigation, Columbus 02:36:29 Adaptive Optics, Scintillation, Artificial Stars 02:48:28 Life Outside Earth? 02:57:50 Gut Microbiome; Building Planet 03:05:00 Zero-Cost Support, Spotify & Apple Follow & Reviews, Sponsors, YouTube Feedback, Social Media, Protocols Book, Neural Network Newsletter Disclaimer & Disclosures

Where will the money come from for the next generation of space stations? Does NASA have plans for a gravity tractor experiment for the Apophis flyby? Which part of the Milky Way can we see? Can there be different types of black holes? Answering all these and more in this Q&A show.

The Exocast team are joined on this show by Jules Fowler, a NSF Graduate Research Fellow at the University of California, Santa Cruz, where they work to improve extreme adaptive optics technologies and seek the signatures of exoplanets in polarized light. Jules also shares insights gleaned from four years working as an analyst and science software engineer at the Space Telescope Science Institute (STScI), where they had the pleasure of collaborating with Exocast's own HannahRead more

Guest: Daniel Harrison, MD Adaptive optics is a promising tool for studying MS-related changes in the retina at a cellular level, providing valuable insights into the disease's progression and potential treatments. Dive further into this line of research with Dr. Daniel Harrison, an Associate Professor of Neurology and the Director of the Division of Multiple Sclerosis and Neuroimmunology at the University of Maryland who presented this research at the 2024 ACTRIMS Forum.

Guest: Daniel Harrison, MD Adaptive optics is a promising tool for studying MS-related changes in the retina at a cellular level, providing valuable insights into the disease's progression and potential treatments. Dive further into this line of research with Dr. Daniel Harrison, an Associate Professor of Neurology and the Director of the Division of Multiple Sclerosis and Neuroimmunology at the University of Maryland who presented this research at the 2024 ACTRIMS Forum.

Sirius, the brightest star in the night sky, is in the south at nightfall. If you keep your eye on it for a few seconds, though, you'll see that Sirius isn't steady. It twinkles fiercely. It gets brighter and fainter, and it changes color rapidly — from red to blue to pure white. The twinkling is beautiful — unless you're an astronomer. Twinkling blurs and distorts the view of stars and other objects. That makes pictures of the universe look fuzzy — not good if you're trying to see the smallest possible details. But astronomers have found a way to overcome the blur — a technique known as adaptive optics. The stars twinkle as their light passes through different layers of the atmosphere. Air masses of different temperature and density “bend” and split the light. So starlight follows a bit of a zig-zaggy path through the air, making its source look blurry. Adaptive optics uses a small, flexible mirror to compensate for the blurring. The system looks at a “guide star” — either a real star, or a fake one created by shining a laser beam high in the sky, causing certain atoms to glow. The mirror flexes to keep the guide star sharp. That keeps the images of the sky in sharp focus as well. Adaptive optics has been around for more than two decades. Today, scientists and engineers are working on “next-generation” versions of the technology — overcoming the beautiful but annoying twinkling of the stars. Script by Damond Benningfield

Today we talk about our current research projects in computational physics and astrophysics. We discuss some important details about Runge-Kutta methods and the nitty gritty of AO. To all our listeners out there, we are so happy to say that you can head over to https://brilliant.org/mpp , and the first 200 of you to sign up will get 20% off your premium membership.   Instagram: @math.physics.podcast Email: math.physics.podcast@gmail.com Twitter: @MathPhysPod

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2023.01.24.525307v1?rss=1 Authors: Kleninfeld, D., Yao, P., Liu, R., Thunemann, M., Boggini, T. Abstract: Two-photon microscopy, combined with appropriate optical labeling, has enabled the study of structure and function throughout nervous systems. This methodology enables, for example, the measurement and tracking of sub-micrometer structures within brain cells, the spatio-temporal mapping of spikes in individual neurons, and the spatio-temporal mapping of transmitter release in individual synapses. Yet the spatial resolution of two-photon microscopy rapidly degrades as imaging is attempted at depths more than a few scattering lengths into tissue, i.e., below the superficial layers that constitute the top 300 to 400 um of neocortex. To obviate this limitation, we measure the wavefront at the focus of the excitation beam and utilize adaptive optics that alters the incident wavefront to achieve an improved focal volume. We describe the constructions, calibration, and operation of a two-photon microscopy that incorporates adaptive optics to restore diffraction-limited resolution throughout the nearly 900 um depth of mouse cortex. Our realization utilizes a guide star formed by excitation of red-shifted dye within the blood serum to directly measure the wavefront. We incorporate predominantly commercial optical, optomechanical, mechanical, and electronic components; computer aided design models of the exceptional custom components are supplied. The design is modular and allows for expanded imaging and optical excitation capabilities. We demonstrate our methodology in mouse neocortex by imaging the morphology of somatostatin-expressing neurons at 700 um beneath the pia, calcium dynamics of layer 5b projection neurons, and glutamate transmission to L4 neurons. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Estimating effective wind speed from Gemini Planet Imager's adaptive optics data using covariance maps by Daniel M. Levinstein et al. on Wednesday 30 November The Earth's turbulent atmosphere results in speckled and blurred images of astronomical objects when observed by ground based visible and near-infrared telescopes. Adaptive optics (AO) systems are employed to reduce these atmospheric effects by using wavefront sensors (WFS) and deformable mirrors. Some AO systems are not fast enough to correct for strong, fast, high turbulence wind layers leading to the wind butterfly effect, or wind-driven halo, reducing contrast capabilities in coronagraphic images. Estimating the effective wind speed of the atmosphere allows us to calculate the atmospheric coherence time. This is not only an important parameter to understand for site characterization but could be used to help remove the wind butterfly in post processing. Here we present a method for estimating the atmospheric effective wind speed from spatio-temporal covariance maps generated from pseudo open-loop (POL) WFS data. POL WFS data is used as it aims to reconstruct the full wavefront information when operating in closed-loop. The covariance maps show how different atmospheric turbulent layers traverse the telescope. Our method successfully recovered the effective wind speed from simulated WFS data generated with the soapy python library. The simulated atmospheric turbulence profiles consist of two turbulent layers of ranging strengths and velocities. The method has also been applied to Gemini Planet Imager (GPI) AO WFS data. This gives insight into how the effective wind speed can affect the wind-driven halo seen in the AO image point spread function. In this paper, we will present results from simulated and GPI WFS data. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.16441v1

Estimating effective wind speed from Gemini Planet Imager's adaptive optics data using covariance maps by Daniel M. Levinstein et al. on Wednesday 30 November The Earth's turbulent atmosphere results in speckled and blurred images of astronomical objects when observed by ground based visible and near-infrared telescopes. Adaptive optics (AO) systems are employed to reduce these atmospheric effects by using wavefront sensors (WFS) and deformable mirrors. Some AO systems are not fast enough to correct for strong, fast, high turbulence wind layers leading to the wind butterfly effect, or wind-driven halo, reducing contrast capabilities in coronagraphic images. Estimating the effective wind speed of the atmosphere allows us to calculate the atmospheric coherence time. This is not only an important parameter to understand for site characterization but could be used to help remove the wind butterfly in post processing. Here we present a method for estimating the atmospheric effective wind speed from spatio-temporal covariance maps generated from pseudo open-loop (POL) WFS data. POL WFS data is used as it aims to reconstruct the full wavefront information when operating in closed-loop. The covariance maps show how different atmospheric turbulent layers traverse the telescope. Our method successfully recovered the effective wind speed from simulated WFS data generated with the soapy python library. The simulated atmospheric turbulence profiles consist of two turbulent layers of ranging strengths and velocities. The method has also been applied to Gemini Planet Imager (GPI) AO WFS data. This gives insight into how the effective wind speed can affect the wind-driven halo seen in the AO image point spread function. In this paper, we will present results from simulated and GPI WFS data. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.16441v1

Impact of local turbulence on high-order adaptive optics by Hugo Nowacki et al. on Monday 26 September We present an experiment set to address a standard specification aiming at avoiding local turbulence inside the Coud'e train of telescopes. Namely, every optical surface should be kept within a 1.5$^circ$ range around ambient temperature. Such a specification represents an important concern and constraint when developing optical systems for astronomy. Our aim was to test its criticality in the context of the development of the VLTI/NAOMI and VLTI/GRAVITY+ adaptive optics. This experiment has been conducted using the hardware of the future Corrective Optics (CO) of GRAVITY+. Optical measurements were performed in order to observe the evolution of turbulence in front of a flat mirror for which the surface temperature was controlled in a range of $22^circ$ above ambient temperature. A time-dependent analysis of the turbulence was led along with a spatial analysis. This experiment shows no influence of temperature on local turbulence. It should be noted however that this result is only applicable to the very specific geometry described in this paper, which is representative of an adaptive optics (AO) system located inside the Coud'e train (facing-down mirror heated on its backface). arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.11630v1

Impact of local turbulence on high-order adaptive optics by Hugo Nowacki et al. on Monday 26 September We present an experiment set to address a standard specification aiming at avoiding local turbulence inside the Coud'e train of telescopes. Namely, every optical surface should be kept within a 1.5$^circ$ range around ambient temperature. Such a specification represents an important concern and constraint when developing optical systems for astronomy. Our aim was to test its criticality in the context of the development of the VLTI/NAOMI and VLTI/GRAVITY+ adaptive optics. This experiment has been conducted using the hardware of the future Corrective Optics (CO) of GRAVITY+. Optical measurements were performed in order to observe the evolution of turbulence in front of a flat mirror for which the surface temperature was controlled in a range of $22^circ$ above ambient temperature. A time-dependent analysis of the turbulence was led along with a spatial analysis. This experiment shows no influence of temperature on local turbulence. It should be noted however that this result is only applicable to the very specific geometry described in this paper, which is representative of an adaptive optics (AO) system located inside the Coud'e train (facing-down mirror heated on its backface). arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.11630v1

Performance characterization and near-realtime monitoring of MUSE adaptive optics modes at Paranal by T. Wevers et al. on Sunday 18 September The Multi Unit Spectroscopic Explorer (MUSE) is an integral field spectrograph on the Very Large Telescope Unit Telescope 4, capable of laser guide star assisted and tomographic adaptive optics using the GALACSI module. Its observing capabilities include a wide field (1 square arcmin), ground layer AO mode (WFM-AO) and a narrow field (7.5"x7.5"), laser tomography AO mode (NFM-AO). The latter has had several upgrades in the 4 years since commissioning, including an optimisation of the control matrices for the AO system and a new sub-electron noise detector for its infra-red low order wavefront sensor. We set out to quantify the NFM-AO system performance by analysing $sim$230 spectrophotometric standard star observations taken over the last 3 years. To this end we expand upon previous work, designed to facilitate analysis of the WFM-AO system performance. We briefly describe the framework that will provide a user friendly, semi-automated way for system performance monitoring during science operations. We provide the results of our performance analysis, chiefly through the measured Strehl ratio and full width at half maximum (FWHM) of the core of the point spread function (PSF) using two PSF models, and correlations with atmospheric conditions. These results will feed into a range of applications, including providing a more accurate prediction of the system performance as implemented in the exposure time calculator, and the associated optimization of the scientific output for a given set of limiting atmospheric conditions. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.07540v1

Probing Photon Statistics in Adaptive Optics Images with SCExAO MEC by Sarah Steiger et al. on Wednesday 14 September We present an experimental study of photon statistics for high-contrast imaging with the Microwave Kinetic Inductance Detector (MKID) Exoplanet Camera (MEC) located behind the Subaru Coronagraphic Extreme Adaptive Optics System (SCExAO) at the Subaru Telescope. We show that MEC measures the expected distributions for both on-axis companion intensity and off-axis intensity which manifests as quasi-static speckles in the image plane and currently limits high-contrast imaging performance. These statistics can be probed by any MEC observation due to the photon-counting capabilities of MKID detectors. Photon arrival time statistics can also be used to directly distinguish companions from speckles using a post-processing technique called Stochastic Speckle Discrimination (SSD). Here, we we give an overview of the SSD technique and highlight the first demonstration of SSD on an extended source -- the protoplanetary disk AB Aurigae. We then present simulations that provide an in-depth exploration as to the current limitations of an extension of the SSD technique called Photon-Counting SSD (PCSSD) to provide a path forward for transitioning PCSSD from simulations to on-sky results. We end with a discussion of how to further improve the efficacy of such arrival time based post-processing techniques applicable to both MKIDs, as well as other high speed astronomical cameras. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.06312v1

BRUTE, PSF Reconstruction for the SOUL pyramid-based Single Conjugate Adaptive Optics facility of the LBT by Carmelo Arcidiacono et al. on Thursday 08 September The astronomical applications greatly benefit from the knowledge of the instrument PSF. We describe the PSF Reconstruction algorithm developed for the LBT LUCI instrument assisted by the SOUL SCAO module. The reconstruction procedure considers only synchronous wavefront sensor telemetry data and a few asynchronous calibrations. We do not compute the Optical Transfer Function and corresponding filters. We compute instead a temporal series of wavefront maps and for each of these the corresponding instantaneous PSF. We tested the algorithm both in laboratory arrangement and in the nighttime for different SOUL configurations, adapting it to the guide star magnitudes and seeing conditions. We nick-named it "BRUTE", Blind Reconstruction Using TElemetry, also recalling the one-to-one approach, one slope-to one instantaneous PSF the algorithm applies. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.03278v1

BRUTE, PSF Reconstruction for the SOUL pyramid-based Single Conjugate Adaptive Optics facility of the LBT by Carmelo Arcidiacono et al. on Thursday 08 September The astronomical applications greatly benefit from the knowledge of the instrument PSF. We describe the PSF Reconstruction algorithm developed for the LBT LUCI instrument assisted by the SOUL SCAO module. The reconstruction procedure considers only synchronous wavefront sensor telemetry data and a few asynchronous calibrations. We do not compute the Optical Transfer Function and corresponding filters. We compute instead a temporal series of wavefront maps and for each of these the corresponding instantaneous PSF. We tested the algorithm both in laboratory arrangement and in the nighttime for different SOUL configurations, adapting it to the guide star magnitudes and seeing conditions. We nick-named it "BRUTE", Blind Reconstruction Using TElemetry, also recalling the one-to-one approach, one slope-to one instantaneous PSF the algorithm applies. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.03278v1

When light from space enters Earth's atmosphere, it is distorted and displaced, something our eyes perceive as “twinkling.”  Adaptive optics can remove a great deal of this distortion, essentially restoring much of the detail we've been robbed off in our view of the stars and galaxies.  Dr. Max, a world-renowned pioneer in this technique, shows us how modern lasers allow her to do this very precisely.  And she discusses how this technique is giving us sharper views of such cosmic events as the collision of nearby galaxies.Speaker: Dr. Claire Max (University of California Observatories)Oct. 3, 2018

Dr. Jack Drummond discusses moons orbiting asteroids, adaptive optics and why astronomy is known as the queen of the sciences.

Asteroide 90 Antiope werd al in 1866 ontdekt. Inmiddels weten we veel meer over dit mysterieuze object, mede dankzij een techniek die bekend staat als Adaptive Optics. Maar hoe mysterieus is ons heelal eigenlijk?

Asteroide 90 Antiope werd al in 1866 ontdekt. Inmiddels weten we veel meer over dit mysterieuze object, mede dankzij een techniek die bekend staat als Adaptive Optics. Maar hoe mysterieus is ons heelal eigenlijk?

This week, we spoke with Erin who loves Adaptive Optics. You can follow Erin on their social media on twitter @so_erinaceous to learn more about them. Don't forget to the hashtag #LoveThisThingCast to tell us about the things you love ! You can follow us on: Facebook: Throuthewindow Twitter: @throuthewindow Instagram: @throuthewindow Tumblr: @throuthewindow

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.05.29.124727v1?rss=1 Authors: Qin, Z., Chen, C., He, S., Wang, Y., Tam, K. F., Ip, N. Y., Qu, J. Y. Abstract: Optical deep brain imaging in vivo at high resolution has remained a great challenge over the decades. Two-photon endomicroscopy provides a minimally invasive approach to image buried brain structures, once it is integrated with a gradient refractive index (GRIN) lens embedded in the brain. However, its imaging resolution and field of view are compromised by the intrinsic aberrations of the GRIN lens. Here, we advance two-photon endomicroscopy by adding adaptive optics(AO) based on the direct wavefront sensing of the descanned fluorescent guide star created by two-photon excitation, which enables effective correction of the aberrations and recovery of diffraction-limited resolution over a much extended imaging volume (300 m on each side). Benefiting from a precompensation strategy based on a lookup table, we achieved in vivo structural imaging of pyramidal neurons at synaptic resolution across all layers of the mouse hippocampus CA1. Moreover, by combining the AO endomicroscope system with a rapid multiplane imaging technique, we demonstrated simultaneous calcium imaging of hippocampal neuronal somata and dendrites in awake behaving mice. Our study holds great promise to facilitate brain research by enabling large-volume deep brain imaging in vivo at high resolution. Copy rights belong to original authors. Visit the link for more info

https://www.youtube.com/watch?v=r8f1750R0X0 Published on Aug 17, 2018. The Earth’s atmosphere keeps us safe from the harsh environment of space, but it also obscures our view into the cosmos. No matter how powerful a telescope you build, the turbulence of the atmosphere limits your resolution. But astronomers and engineers have an amazing technology that allows a telescope to peer into space as if the atmosphere isn’t even there, producing images from here on the ground which are as sharp and clear as if the telescope was out in space. It’s called adaptive optics, and we’re now at the point where the most powerful ground-based telescopes have matched and even exceeded the capability of space telescopes.   We've added a new way to donate to 365 Days of Astronomy to support editing, hosting, and production costs. Just visit: https://www.patreon.com/365DaysOfAstronomy and donate as much as you can! Share the podcast with your friends and send the Patreon link to them too! Every bit helps! Thank you! ------------------------------------ Do go visit http://astrogear.spreadshirt.com/ for cool Astronomy Cast and CosmoQuest t-shirts, coffee mugs and other awesomeness! http://cosmoquest.org/Donate This show is made possible through your donations. Thank you! (Haven't donated? It's not too late! Just click!) The 365 Days of Astronomy Podcast is produced by Astrosphere New Media. http://www.astrosphere.org/ Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org.

Help us make Syzygy even better! Tell your friends and give us a review, or show your support on Patreon: patreon.com/syzygypodSyzygy is produced by Chris Stewart and co-hosted by Dr Emily Brunsden from the Department of Physics at the University of York.On the web: syzygy.fm | Twitter: @syzygypodThings we talk about in this episode:The Giant Magellan TelescopeA good video about the GMT from National GeographicXKCD on telescope namesThe plain old Magellan TelescopeSALT, the South African Large TelescopeThe Very Large TelescopeThe European Extremely Large TelescopeThe Overwhelmingly Large Telescope (now cancelled)The Thirty Metre TelescopeMaking Magellan Mirrors (video)Description of the mirror process (video)The GMT Science BookActive Optics and Adaptive Optics

The Earth’s atmosphere keeps us safe from the harsh environment of space, but it also obscures our view into the cosmos. No matter how powerful a telescope you build, the turbulence of the atmosphere limits your resolution. But astronomers and engineers have an amazing technology that allows a telescope to peer into space as if the atmosphere isn’t even there, producing images from here on the ground which are as sharp and clear as if the telescope was out in space. It’s called adaptive optics, and we’re now at the point where the most powerful ground-based telescopes have matched and even exceeded the capability of space telescopes.

Who’s got the sharpest eye? We’ll see what happens when you turbo-charge a ground-based telescope with Adaptive Optics.

How do neuroscientists see through layers of grey matter to produce images of cells that are deeply embedded in living brains? Dr. Na Ji from HHMI's Janelia Research Campus explains how optical tricks from astronomy can be applied to solve this problem. We cover her exciting academic career from China to California and beyond. Tune in to get the inside scoop on the next big advancements in neuroscience.

Who's got the sharpest eye? We'll see what happens when you turbo charge a ground-based telescope with Adaptive Optics

Who's got the sharpest eye? We'll see what happens when you turbo charge a ground based telescope with Adaptive Optics

400 years ago, our world-view changed when Galileo proved that the Earth was not the center of the universe but orbits around the Sun. 15 years ago the world shifted again when the first planets were discovered orbiting other stars. Last year, using adaptive optics and the 10 meter W.M. Keck telescope in Hawaii, a Lawrence Livermore National Lab team produced the first ever picture of another solar system. One day, these techniques may even lead to an image with a pale blue dot circling a nearby star - another Earth. Join LLNL astronomer Bruce Macintosh and Lisa Poyneer as they describe the new technologies that made these pictures possible. Series: "Lawrence Livermore National Lab Science on Saturday" [Science] [Show ID: 20235]

400 years ago, our world-view changed when Galileo proved that the Earth was not the center of the universe but orbits around the Sun. 15 years ago the world shifted again when the first planets were discovered orbiting other stars. Last year, using adaptive optics and the 10 meter W.M. Keck telescope in Hawaii, a Lawrence Livermore National Lab team produced the first ever picture of another solar system. One day, these techniques may even lead to an image with a pale blue dot circling a nearby star - another Earth. Join LLNL astronomer Bruce Macintosh and Lisa Poyneer as they describe the new technologies that made these pictures possible. Series: "Lawrence Livermore National Lab Science on Saturday" [Science] [Show ID: 20235]

400 years ago, our world-view changed when Galileo proved that the Earth was not the center of the universe but orbits around the Sun. 15 years ago the world shifted again when the first planets were discovered orbiting other stars. Last year, using adaptive optics and the 10 meter W.M. Keck telescope in Hawaii, a Lawrence Livermore National Lab team produced the first ever picture of another solar system. One day, these techniques may even lead to an image with a pale blue dot circling a nearby star - another Earth. Join LLNL astronomer Bruce Macintosh and Lisa Poyneer as they describe the new technologies that made these pictures possible. Series: "Lawrence Livermore National Lab Science on Saturday" [Science] [Show ID: 20235]

400 years ago, our world-view changed when Galileo proved that the Earth was not the center of the universe but orbits around the Sun. 15 years ago the world shifted again when the first planets were discovered orbiting other stars. Last year, using adaptive optics and the 10 meter W.M. Keck telescope in Hawaii, a Lawrence Livermore National Lab team produced the first ever picture of another solar system. One day, these techniques may even lead to an image with a pale blue dot circling a nearby star - another Earth. Join LLNL astronomer Bruce Macintosh and Lisa Poyneer as they describe the new technologies that made these pictures possible. Series: "Lawrence Livermore National Lab Science on Saturday" [Science] [Show ID: 20235]

We study the initial mass function (IMF) of NGC 3603, one of the most massive galactic star-forming regions, to answer a fundamental question in current astrophysics - is the IMF universal, or does it vary? Using our very deep high angular resolution images obtained with the NAOS-CONICA adaptive optics system at the VLT/ESO, we have successfully revealed the low-mass stellar population in the cluster core down to about 0.4 Msun (50 % completeness limit). Based on the JHKsL' color-magnitude and color-color diagrams, we first derive an average age 0.7 Myr for the pre-main sequence stars, and an upper limit of ~2.5 Myr for the main sequence stars. We find an average foreground extinction of Av = 4.5 +- 0.5 mag, with a radial increase of Delta_Av ~ 2.0 mag towards larger radii (r < 50''). From the infrared excess emission identified in the Ks - L' vs J - H color-color diagram, we measure a disk fraction of ~25 % for stars with M > 0.9 Msun in the cluster center (r < 10''). Applying a field star rejection and correcting for incompleteness, we derive the Ks-band luminosity function (LF) for stars simultaneously detected in the JHKs-bands. The LF follows a power-law with an index of alpha ~ 0.27, and shows no turnover or truncation within the detection limit. The IMF for stars within r < 110'' is reasonably fitted by a single power-law with index Gamma ~ -0.74 in the mass range of $0.4 - 20 Msun. This is substantially flatter than the Salpeter-like IMF (Gamma = -1.35). The IMF power-law index decreases from Gamma ~ -0.31 at r < 5'' to Gamma ~ -0.86 at 30'' < r < 110''. This radial steepening of the IMF mainly occurs in the inner r < 30'' field, indicating mass segregation at the very center of the starburst cluster. Analyzing the radial mass density profile, we derive a cluster core radius of ~4''.8 (~0.14 pc), and a lower limit of ~110'' (~3.2 pc) for the cluster size. We also derive an upper limit of r ~ 1260'' (~37 pc) for the cluster size adopting an estimate of the tidal radius of the cluster. Based on the de-projected stellar density distribution, we estimate the total mass and the half-mass radius of NGC 3603 to be about 1.0 - 1.6 x 10^4 Msun and 25'' - 50'' (~0.7 - 1.5 pc), respectively. The derived core radius is > 6 x 10^4 Msun pc^-3. The estimate of the half-mass relaxation time for stars with a typical mass of 1 Msun is 10 - 40 Myr, suggesting that the intermediate- and low-mass stars have not yet been affected significantly by the dynamical relaxation in the cluster. The relaxation time for the high-mass stars is expected to be much smaller, and is comparable to the age of the cluster. We can thus not conclude if the mass segregation of the high-mass stars is primordial or caused by dynamical evolution. Our observation covers at least ~67 % of intermediate- and low-mass stars in NGC 3603, and the stars residing outside the observed field can merely steepen the IMF by Delta_Gamma < 0.16. Therefore, because of the almost constant IMF beyond a radius r > 30'', we are confident that our IMF adequately describes the whole NGC 3603 starburst cluster. We also thoroughly analyze the systematic uncertainties in our IMF determination. We conclude that the power-law index of NGC 3603 including the systematic uncertainties is Gamma = -0.74^{+0.62}_{-0.47}. Our result thus supports the hypothesis of a top-heavy IMF in starbursts, especially in combination with other studies of similar clusters such as the Arches cluster and the Galactic Center cluster.