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  • richardmitnick 12:56 pm on January 12, 2017 Permalink | Reply
    Tags: , , IC 3639, Monster black holes, , , NGC 1448, SPACE SCIENCE LAB UC Berkeley, ,   

    From Space Science Laboratory at UC Berkeley: “NuSTAR – Black Holes Hide in our Cosmic Backyard” 

    UC Berkeley

    UC Berkeley

    SSL UC Berkeley

    Space Science Laboratory

    1
    No image caption. No image credit.

    NASA/NuSTAR

    NuSTAR

    January 12, 2017
    Christopher Scholz

    Monster black holes sometimes lurk behind gas and dust, hiding from the gaze of most telescopes. But they give themselves away when material they feed on emits high-energy X-rays that NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array) mission can detect. That’s how NuSTAR recently identified two gas-enshrouded supermassive black holes, located at the centers of nearby galaxies.

    “These black holes are relatively close to the Milky Way, but they have remained hidden from us until now,” said Ady Annuar, a graduate student at Durham University in the United Kingdom, who presented the results at the American Astronomical Society meeting in Grapevine, Texas. “They’re like monsters hiding under your bed.”

    Both of these black holes are the central engines of what astronomers call “active galactic nuclei,” a class of extremely bright objects that includes quasars and blazars. Depending on how these galactic nuclei are oriented and what sort of material surrounds them, they appear very different when examined with telescopes.

    Active galactic nuclei are so bright because particles in the regions around the black hole get very hot and emit radiation across the full electromagnetic spectrum — from low-energy radio waves to high-energy X-rays. However, most active nuclei are believed to be surrounded by a doughnut-shaped region of thick gas and dust that obscures the central regions from certain lines of sight. Both of the active galactic nuclei that NuSTAR recently studied appear to be oriented such that astronomers view them edge-on. That means that instead of seeing the bright central regions, our telescopes primarily see the reflected X-rays from the doughnut-shaped obscuring material.

    “Just as we can’t see the sun on a cloudy day, we can’t directly see how bright these active galactic nuclei really are because of all of the gas and dust surrounding the central engine,” said Peter Boorman, a graduate student at the University of Southampton in the United Kingdom.

    Boorman led the study of an active galaxy called IC 3639, which is 170 million light years away.

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    IC 3639, a galaxy with an active galactic nucleus, is seen in this image combining data from the Hubble Space Telescope and the European Southern Observatory.

    This galaxy contains an example of a supermassive black hole hidden by gas and dust. Researchers analyzed NuSTAR data from this object and compared them with previous observations from NASA’s Chandra X-Ray Observatory and the Japanese-led Suzaku satellite.

    NASA/Chandra Telescope
    NASA/Chandra Telescope

    JAXA/Suzaku satellite
    JAXA/Suzaku satellite

    The findings from NuSTAR, which is more sensitive to higher energy X-rays than these observatories, confirm the nature of IC 3639 as an active galactic nucleus that is heavily obscured, and intrinsically much brighter than observed.

    Researchers analyzed NuSTAR data from this object and compared them with previous observations from NASA’s Chandra X-Ray Observatory and the Japan-led Suzaku satellite. NuSTAR also provided the first precise measurement of how much material is obscuring the central engine of IC 3639, allowing researchers to determine how luminous this hidden monster really is.

    More surprising is the spiral galaxy that Annuar focused on: NGC 1448.

    6
    NGC 1448 (also designated NGC 1457 and ESO 249-16) is a spiral galaxy located about 60 million light-years away in the constellation Horologium. It has a prominent disk of young and very bright stars surrounding its small, shining core. The galaxy is receding from us with 1168 kilometers per second.

    NGC 1448 has recently been a prolific factory of supernovae, the dramatic explosions that mark the death of stars: after a first one observed in this galaxy in 1983 (SN 1983S), two more have been discovered during the past decade.

    Visible as a red dot inside the disc, in the upper right part of the image, is the supernova observed in 2003 (Type II supernova SN 2003hn), whereas another one, detected in 2001 (Type Ia supernova SN 2001el), can be noticed as a tiny blue dot in the central part of the image, just below the galaxy’s core. If captured at the peak of the explosion, a supernova might be as bright as the whole galaxy that hosts it.

    A Type Ia supernova is a result from the violent explosion of a white dwarf star. This category of supernovae produces consistent peak luminosity. The stability of this luminosity allows these supernovae to be used as standard candles to measure the distance to their host galaxies because the visual magnitude of the supernovae depends primarily on the distance.

    A Type II supernova results from the rapid collapse and violent explosion of a massive star. A star must have at least 8 times, and no more than 40–50 times the mass of the Sun for this type of explosion. It is distinguished from other types of supernova by the presence of hydrogen in its spectrum. Type II supernovae are mainly observed in the spiral arms of galaxies and in H II regions, but not in elliptical galaxies.

    This image was obtained using the 8.2-metre telescopes of ESO’s Very Large Telescope. It combines exposures taken between July 2002 and the end of November 2003.

    ESO/VLT at Cerro Paranal, Chile, ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level
    ESO/VLT at Cerro Paranal, Chile, ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

    Credit: ESO

    The black hole in its center was only discovered in 2009, even though it is at the center of one of the nearest large galaxies to our Milky Way. By “near,” astronomers mean NGC 1448 is only 38 million light years away (one light year is about 6 trillion miles).

    Annuar’s study discovered that this galaxy also has a thick column of gas hiding the central black hole, which could be part of a doughnut-shaped region. X-ray emission from NGC 1448, as seen by NuSTAR and Chandra, suggests for the first time that, as with IC 3639, there must be a thick layer of gas and dust hiding the active black hole in this galaxy from our line of sight.

    Researchers also found that NGC 1448 has a large population of young (just 5 million year old) stars, suggesting that the galaxy produces new stars at the same time that its black hole feeds on gas and dust. Researchers used the European Southern Observatory New Technology Telescope to image NGC 1448 at optical wavelengths, and identified where exactly in the galaxy the black hole should be. A black hole’s location can be hard to pinpoint because the centers of galaxies are crowded with stars. Large optical and radio telescopes can help detect light from around black holes so that astronomers can find their location and piece together the story of their growth.

    “It is exciting to use the power of NuSTAR to get important, unique information on these beasts, even in our cosmic backyard where they can be studied in detail,” said Daniel Stern, NuSTAR project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, California.

    NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR’s mission operations center is at UC Berkeley, and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center. ASI provides the mission’s ground station and a mirror archive. JPL is managed by Caltech for NASA.

    See the full article here .

    Please help promote STEM in your local schools.

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    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

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  • richardmitnick 2:44 pm on February 20, 2016 Permalink | Reply
    Tags: , , , SPACE SCIENCE LAB UC Berkeley   

    From SSL: “MAVEN Instruments Study the Solar Wind at Mars” 

    SSL UC Berkeley

    Space Science Lab, UC Berkeley

    February 20, 2016
    Christopher Scholz

    The ‪MAVEN‬ spacecraft is equipped with several instruments devoted to measuring the solar wind and how solar energetic particles and extreme ultraviolet irradiance interact with Mars’ upper atmosphere.

    Solar Wind Electron Analyzer (SWEA)-The Solar Wind Electron Analyzer (SWEA) is a part of the Particles and Fields (P&F) Package and will measure the solar wind and ionospheric electrons.

    Goals:

    Deduce magneto-plasma topology in and above the Martian ionosphere based on electron spectra and pitch angle distributions
    Measure atmospheric electron impact ionization effects

    Observations:

    Measure energy and angle distributions of electrons in the Mars environment
    Determine magnetic topology from pitch angle distributions
    Measure solar wind, sheath and primary ionospheric photoelectron spectrum
    Determine electron impact ionization rates
    Measure auroral electron populations
    Evaluate plasma environment

    Technical details and heritage:

    Hemispherical Electrostatic Analyzer with deflectors
    Electrons with energies from 5 eV to 4.6 keV
    FOV 360o x 120o (Azimuth x Elevation)
    Angular resolution 22.5o in azimuth x 20o in elevation
    Energy fluxes 103 to 109 eV/cm2-s-ster-eV
    Energy resolution: ΔE/E = 17%, FWHM (capability for 9% below 50 eV)
    Time resolution: 2 sec
    Mounted at end of 1.5-meter boom
    Heritage from STEREO SWEA

    Solar Wind Ion Analyzer (SWIA)-The Solar Wind Ion Analyzer (SWIA) is a part of the Particles and Fields (P&F) Package and measures the solar wind and magnetosheath proton flow around Mars and constrains the nature of solar wind interactions with the upper atmosphere.

    Goals:

    Determine the ionization rates of neutrals from charge exchange, as an input to atmospheric loss processes
    Determine the pickup acceleration of newly formed ions by the v x B electric field
    Measure the flow of solar wind energy through the Martian magnetosphere
    Measure the structure and variability of the Martian magnetosphere
    Measure basic space plasma phenomena, including reconnection, flux ropes, plasmoids, bulk plasma escape, auroral processes, and boundary instabilities, throughout the Martian system

    Observations:

    Measure the properties of solar wind and magnetosheath ions, including density, temperature, and velocity, in order to determine the energy input to the upper atmosphere, the charge exchange rate, and the bulk plasma flow from solar wind speeds (~350 to ~1000 km/s) down to stagnating magnetosheath speeds (tens of km/s)

    Technical details and heritage:

    Coarse 3d covers 360°x90° with 22.5° resolution and energies 5 eV/q – 25 keV/q
    Fine 3d covers solar wind beam w/ 4.5° resolution and 10% energy windows
    Intrinsic time resolution of 4 s
    Mechanical attenuator provides variable dynamic range to cover from tenuous magnetosphere up to extreme solar wind fluxes [5×104 to 7×1011 eV/(cm2 s sr eV)]
    Heritage from Wind, FAST, and THEMIS

    Suprathermal and Thermal Ion Composition (STATIC)-The Suprathermal and Thermal Ion Composition (STATIC) instrument is part of the Particles and Fields (P&F) Package and measures thermal ions to moderate energy escaping ions.

    Goals:

    Measure the source ion populations near periapsis, the heated ionospheric ions at intermediate altitudes that achieve escape velocity, and the pickup acceleration of these ions in the magnetosheath and solar wind
    Allow direct measurements of the Martian sheath plasma, separating shocked solar wind and planetary ions that populate the sheath and plasma sheet

    Observations:

    Escaping ions and processes
    Composition of thermal to energetic ions; energy distributions and pitch angle variations
    Ionospheric Ions 0.1-10 eV
    Tail Superthermal ions (5-100eV)
    Pick-up Ions (100-20,000 eV)
    Key ions H+, O+, O2+, CO2+

    Technical details and heritage:

    Toroidal Electrostatic Analyzer with Time of Flight section
    Mass Range 1-70 AMU, ΔM/M > 4
    Energy range ~0.1 eV to 30 keV, ΔE/E~15%
    FOV 360o X 90o
    Angular Resolution 22.5o x 6o
    Energy Flux < 104 to 109 eV/cm2-s-sr-eV (to 1012 w/attenuators for low energy beam)
    Can be oriented to measure either upwelling/downwelling or horizontal flows
    Heritage from Cluster CODIF

    Solar Energetic Particle (SEP)-The Solar Energetic Particle (SEP) instrument is part of the Particles and Fields (P&F) Package and determines the impact of SEPs on the upper atmosphere.

    Goals:

    Determine SEP input into the atmosphere as a function of altitude
    Determine SEP heating, ionization, and sputtering of upper atmosphere
    Detect the highest energy pickup ions (>30 to 100s of keV)

    Observations:

    Characterize solar particles in an energy range that affects upper atmosphere and ionospheric processes (~120 – 200 km)
    Time resolution adequate to capture major SEP events (<1 hour)

    Technical details and heritage:

    Two dual double-ended telescopes
    Four look directions per species, optimized for parallel and perpendicular Parker Spiral viewing
    Protons and heavier ions from ~25 keV to 12 MeV
    Electrons from ~25 keV to 1 MeV
    Energy fluxes 10 to 106 eV/cm2-sec-ster-eV
    Better than 50% energy resolution
    Heritage from (nearly identical to) SST on THEMIS

    Langmuir Probe and Waves (LPW)Langmuir Probe and Waves (LPW)-The Langmuir Probe and Waves (LPW) instrument is part of the Particles and Fields (P&F) Package and determines ionospheric properties, wave heating of the upper atmosphere, and solar EUV input to the atmosphere.

    Goals:

    Measure the in situ electron density and electron temperature from the ionospheric peak up to the nominal ionopause location. It will also measure the electric field wave power important for ion heating
    Characterize the basic state of the ionosphere—its global structure, variability, and thermal properties
    Determine the effects of solar wind generated plasma waves and auroral precipitation on ionosphere heating and relationship to plasma escape
    Determine the electron temperatures required for deriving ion recombination rates and ionospheric chemistry
    Identify the ionopause and detached, escaping ionosphere clouds

    Observations:

    Electron temperature and number density throughout upper atmosphere
    Electric field wave power at low frequencies important for ion heating
    Wave spectra of naturally emitted and actively stimulated Langmuir waves to calibrate density measurements

    Technical details and heritage:

    Cylindrical sensors on two 7-meter booms
    Sensor I-V sweeps (at least ±50 V range)
    Low frequency (f: 0.05-10 Hz) E-field power; sensitivity 10-8 (V/m)2/Hz (f0/f)2 where fo=10 Hz and 100% bandwidth
    E-Spectra measurements up to 2 MHz
    White noise (50 kHz – 2 MHz ) sounding
    Thermal Electron density 100 to 106 cm-3
    Electron temperatures 500 to 5000oK
    Heritage from THEMIS and RBSP

    Extreme Ultraviolet (EUV) Monitor-The Extreme Ultraviolet (EUV) monitor is part of the Langmuir Probe and Waves (LPW) instrument and measures solar EUV input and variability, and wave heating of the Martian upper atmosphere.

    Goals:

    Measure solar emissions from different regions of the Sun in three distinct EUV bands
    Three channels will provide a complete EUV spectrum (0.1-190 nm) to serve as a proxy for input to the Flare Irradiance Spectral Model (FISM) model

    Observations:

    Solar EUV irradiance variability at wavelengths important for ionization, dissociation, and heating of the upper atmosphere (wavelengths shortward of HI Ly-α 121.6 nm)

    Technical details and heritage:

    Three photometers at key wavelengths representing different temperature solar emissions (0.1-7, 17-22, and 121.6 nm)
    Full spectrum (0-200 nm) derived from measurements using Flare Irradiance Spectral Model (FISM)
    Heritage from TIMED, SORCE, SDO, and rocket instruments

    Magnetometer (MAG)-The Magnetometer (MAG) is a part of the Particles and Fields (P&F) Package and measures interplanetary solar wind and ionospheric magnetic fields.

    Goals:

    Measure vector magnetic field
    Characterize solar wind interaction
    Support particles and fields package (ions, electrons, energetic particles & waves)

    Observations:

    Vector magnetic field in the unperturbed solar wind (B ~ 3 nT), magnetosheath (B ~ 10-50 nT), and crustal magnetospheres (B < 3000 nT), with the ability to spatially resolve crustal magnetic cusps (horizontal length scales of ~100 km)

    Technical details and heritage:

    Two sensors, outboard of solar array
    Magnetic field over a dynamic range of ~60,000 nT; resolution 0.05 nT
    32 samples/sec intrinsic sample rate averaged and decimated as necessary
    Sensor scale factor accuracy of 0.05%
    Heritage from MGS, Voyager, AMPTE, GIOTTO, CLUSTER, Lunar Prospector, MESSENGER , STEREO, Juno, and Van Allen Probes

    NASA MAVEN
    NASA/Mars MAVEN

    These experiments have been specifically designed to determine whether space weather events increase atmospheric escape rates to historically important levels.

    In analyzing data from these instruments, MAVEN scientists will take three approaches to derive the history of Mars’ atmosphere:

    1. Use ratios of stable isotopes to determine the integrated loss to space
    2. Use observed changes in escape in response to changing energetic inputs to directly extrapolate back in time
    3. Model escape processes using current conditions and extrapolate models back in time

    Taking these approaches enables our team scientists to determine how various space weather events affect the upper atmosphere of Mars today and how they have contributed to its evolution over time. Capturing events of different magnitudes becomes more likely over time and contributes to producing more accurate model extrapolations back in time.

    MAVEN data is allowing scientists to:

    Investigate atmospheric escape response to regular solar wind variations and to major events (solar flares, coronal mass ejections)
    Update an estimate of solar wind evolution
    Determine how solar energetic particles contribute to escape, and
    Estimate integrated historical loss to space

    NASA Goddard

    For images, fuller descriptions, publications, see the original SSL article.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    SSL UC Berkeley campus

     
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