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Rebecca Centeno HAO 75th Anniversary September 3, 2015
CSAC: BUILDING CAPABILITY FOR NEXT GENERATION OBSERVATORIES
Rebecca Centeno HAO 75th Anniversary September 3, 2015
MAGNETIC FIELDS AND SUNSPOTS
Scheiner, 1625
NST/BBSO
Rebecca Centeno HAO 75th Anniversary September 3, 2015
THE SOLAR CYCLE
The Solar Cycle 13
Sunspot areas are also available from a number of solar observatories including: Catania (1978 –1999), Debrecen (1986 – 1998), Kodaikanal (1906 – 1987), Mt. Wilson (1917 – 1985), Rome (1958 –2000), and Yunnan (1981 – 1992). While individual observatories have data gaps, their data arevery useful for helping to maintain consistency over the full interval from 1874 to the present.
The combined RGO USAF/NOAA datasets are available online (RGO).These datasets have additional information that is not reflected in sunspot numbers – positional
information – both latitude and longitude. The distribution of sunspot area with latitude (Figure 8)shows that sunspots appear in two bands on either side of the Sun’s equator. At the start of eachcycle spots appear at latitudes above about 20 – 25°. As the cycle progresses the range of latitudeswith sunspots broadens and the central latitude slowly drifts toward the equator, but with a zoneof avoidance near the equator. This behavior is referred to as “Sporer’s Law of Zones” by Maunder(1903) and was famously illustrated by his “Butterfly Diagram” (Maunder, 1904).
1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010DATE
AVERAGE DAILY SUNSPOT AREA (% OF VISIBLE HEMISPHERE)
0.0
0.1
0.2
0.3
0.4
0.5
1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010DATE
SUNSPOT AREA IN EQUAL AREA LATITUDE STRIPS (% OF STRIP AREA) > 0.0% > 0.1% > 1.0%
90S
30S
EQ
30N
90N
12 13 14 15 16 17 18 19 20 21 22 23
http://solarscience.msfc.nasa.gov/images/BFLY.pdf HATHAWAY/NASA/MSFC 2010/01
DAILY SUNSPOT AREA AVERAGED OVER INDIVIDUAL SOLAR ROTATIONS
Figure 8: Sunspot area as a function of latitude and time. The average daily sunspot area for each solarrotation since May 1874 is plotted as a function of time in the lower panel. The relative area in equalarea latitude strips is illustrated with a color code in the upper panel. Sunspots form in two bands, one ineach hemisphere, that start at about 25° from the equator at the start of a cycle and migrate toward theequator as the cycle progresses.
3.3 10.7 cm solar flux
The 10.7 cm Solar Flux is the disk integrated emission from the Sun at the radio wavelengthof 10.7 cm (2800 MHz) (cf. Tapping and Charrois, 1994). This measure of solar activity hasadvantages over sunspot numbers and areas in that it is completely objective and can be madeunder virtually all weather conditions. Measurements of this flux have been taken daily by theCanadian Solar Radio Monitoring Programme since 1946. Several measurements are taken eachday and care is taken to avoid reporting values influenced by flaring activity. Observations were
Living Reviews in Solar Physicshttp://www.livingreviews.org/lrsp-2010-1
Hathaway, 2010
NSO
Rebecca Centeno HAO 75th Anniversary September 3, 2015
THE SMALLER SCALES
HMI/SDO
1 arcsec ~ 750 km 40 arcsec
Rebecca Centeno HAO 75th Anniversary September 3, 2015
SPACE WEATHER
Image credit: NASA
"Space Weather" refers to the ever-changing solar-driven events and their
interaction with the interplanetary medium
Rebecca Centeno HAO 75th Anniversary September 3, 2015
THE SUN’S MAGNETISM…
… REACHES OUT INTO SPACE
Rebecca Centeno HAO 75th Anniversary September 3, 2015
PARKER SPIRAL
Heliospheric current sheet (source: Lempfi, NASA)
Rebecca Centeno HAO 75th Anniversary September 3, 2015
"A medieval
missionary tells that he has found the point
where heaven and
Earth meet..."
Rebecca Centeno HAO 75th Anniversary September 3, 2015
MEASURING THE SUN’S MAGNETISM
It is an incredibly powerful tool for remote sensing of magnetic fields in the Sun’s atmosphere
Spectropolarimetry is the measurement of the distribution of energy and polarization of the
light as a function of frequency
Rebecca Centeno HAO 75th Anniversary September 3, 2015
SPECTRO-
Rebecca Centeno HAO 75th Anniversary September 3, 2015
-POLARI(METRY)
+ - - -I Q U V
Zeeman splitting — Field strength Linear Polarization — Transverse field
Circular polarization — Longitudinal field Polarization fraction — Magnetic filling factor
Rebecca Centeno HAO 75th Anniversary September 3, 2015
PHYSICAL INTERPRETATION
(Polarized) Radiative Transfer Equation:
Statistical Equilibrium Equations: !
Tell us how many atoms there are in each possible energy configuration
Describes how a beam of light loses energy by absorption, gains it by emission and
redistributes it by scattering as it travels
Rebecca Centeno HAO 75th Anniversary September 3, 2015
INVERSION CODESTools that allow us to interpret the light that comes from the Sun
RADIATIVE TRANSFER
ATMOSPHERIC MODEL
STATISTICAL EQUILIBRIUM
OBSERVATIONSatomic populations
radiation output
solve
solve
compare
feedb
ack
feedback
Rebecca Centeno HAO 75th Anniversary September 3, 2015
THE SUN IN MANY LIGHTS
Different physical regimes reign in
different parts of the Sun’s atmosphere…
…and different lights allow us to probe them
Rebecca Centeno HAO 75th Anniversary September 3, 2015
THE GOAL
Schrijver et al.
The goal is to obtain the 3D topology of the magnetic field
Rebecca Centeno HAO 75th Anniversary September 3, 2015
CHROMOSPHERIC CHALLENGE
CaII 8542, IBIS, ReardonHinode/SP
We know how to do this…
for the Photosphere
BUT it’s a whole different
story for the Chromosphere
Rebecca Centeno HAO 75th Anniversary September 3, 2015
CSACCSAC is the Community Spectropolarimetric Analysis Center. It was born as an NCAR/HAO strategic initiative circa 2003. It heavily relied on HAO’s heritage and long-standing expertise in the development of spectropolarimeters and the interpretation of polarized light for remote sensing of magnetic fields in the Sun’s atmosphere.
COMMUNITY
Rebecca Centeno HAO 75th Anniversary September 3, 2015
CURRENTLY
Hinode/SP data streamCalibrated data
Spectral line inversions
Software tools Inversion codes Disambiguation codes
Documentation
User support
Software Manuals General Information
E-mail Wiki page (under dev.)
Rebecca Centeno HAO 75th Anniversary September 3, 2015
HINODE/SP DATA STREAMQ U VI
Hinode/SP
Rebecca Centeno HAO 75th Anniversary September 3, 2015
ChroMag
BUILDING CAPABILITY
New instruments
“New” spectral domains
Community involvement
Service Education
Collaboration DSET
CaII 8542, Reardon
DKIST, NSO
Rebecca Centeno HAO 75th Anniversary September 3, 2015
EDUCATIONHale Collage
Spring 2016 @ CU “Topics in Solar Observation
Techniques”
1. Solar Spectropolarimetry & Instrumentation !2. Spectropolarimetric Diagnostic Techniques !3. Off-limb Coronagraphy & Spectroscopy
ASTR–7500 . . . . . . . . . . . . . . . Topics in Solar Observation Techniques
Instructors: V. Pillet, R. Centeno Elliott, H. Uitenbroek, S. Cranmer
Semester: Spring 2016, Times & Location TBD
Course web page: http://lasp.colorado.edu/∼cranmer/ASTR_7500_2016/
This web-enabled course is the third offering of the George Ellery Hale CollaborativeGraduate Education (COLLAGE) Program, a joint effort between CU Boulder, theNational Solar Observatory (NSO), New Jersey Institute of Technology (NJIT), Univer-sity of Hawaii (UH), New Mexico State University (NMSU), Montana State University(MSU), and the High Altitude Observatory (HAO).
In this course we will cover the basics of spectropolarimetric instrumentation and mea-surement techniques, diagnostics of the plasma properties and magnetic field of the solaratmosphere, occulting coronagraphs, and emission-line spectroscopy of the solar corona.The entire course will be web-cast to the participating institutions (with additional in-structors lined up to facilitate local discussion). Some part of the material will be pre-recorded for earlier viewing, with the “flipped classroom” model being used for in-classdiscussion.
At CU Boulder, this course is an elective for APS graduate students. A recommended pre-requisite or co-requisite isObservations, Data Analysis, & Statistics (ASTR–5550).
Rebecca Centeno HAO 75th Anniversary September 3, 2015
THANKS!
https://www2.hao.ucar.edu/csac