csac: building capability for next generation observatories

Rebecca Centeno HAO 75th Anniversary September 3, 2015

CSAC: BUILDING CAPABILITY FOR NEXT GENERATION OBSERVATORIES


MAGNETIC FIELDS AND SUNSPOTS

Scheiner, 1625

NST/BBSO


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


THE SMALLER SCALES

HMI/SDO

1 arcsec ~ 750 km 40 arcsec


SPACE WEATHER

Image credit: NASA

"Space Weather" refers to the ever-changing solar-driven events and their

interaction with the interplanetary medium


THE SUN’S MAGNETISM…

… REACHES OUT INTO SPACE


PARKER SPIRAL

Heliospheric current sheet (source: Lempfi, NASA)


"A medieval

missionary tells that he has found the point

where heaven and

Earth meet..."


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


SPECTRO-


-POLARI(METRY)

+ - - -I Q U V

Zeeman splitting — Field strength Linear Polarization — Transverse field

Circular polarization — Longitudinal field Polarization fraction — Magnetic filling factor


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


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


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


THE GOAL

Schrijver et al.

The goal is to obtain the 3D topology of the magnetic field


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


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


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.)


HINODE/SP DATA STREAMQ U VI

Hinode/SP


ChroMag

BUILDING CAPABILITY

New instruments

“New” spectral domains

Community involvement

Service Education

Collaboration DSET

CaII 8542, Reardon

DKIST, NSO


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).


THANKS!

https://www2.hao.ucar.edu/csac

https://www2.hao.ucar.edu/csac

csac: building capability for next generation observatories

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