Unsolved problems in photosphericscience
Luis R. Bellot Rubio
Instituto de Astrofísica de Andalucía (CSIC)
Granada, Spain

Three key problems• Magnetoconvection in the solar photosphere– Sunspots• Origin and evolution of quiet Sun flux
– Network– Internetwork• Connection photosphere-chromosphere– Cancellation events– Emerging IN fields

2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

Magnetoconvection in the umbra
Energy transport in thepresence of vertical field?
What’s the subsurface
structure of a sunspot?

Ortiz, Bellot Rubio, Rouppe van der Voort, ApJ (in press)

CRISP @ SST + AO, Fe I 630 nm
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Socas-Navarro et al., ApJ (2004)

Luis R. Bellot Rubio!

Magnetoconvection in the umbra

Ortiz, Bellot Rubio, Rouppe van der Voort, ApJ (in press)

CRISP @ SST + AO, Fe I 630 nm
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Schüssler & Vögler, ApJL (2006)

Luis R. Bellot Rubio!

Mm

Magnetoconvection in the umbra

Mm

Schüssler & Vögler, ApJL (2006)• Umbral dots with upflows and central dark lanes• Downflows at ends of dark lanes and periphery of UDs• High spatial resolution needed: ~ 0.1"
• Very low scattered light levels

2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

Magnetoconvection in the umbra
Continuum intensity

20% bisector velocity

80% bisector velocity

Ortiz, Bellot Rubio, Rouppe van der Voort, ApJ (in press)

Spectropolarimetry at 0.14": downflows observed near the edge of UDs
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

Magnetoconvection in the umbra

Ortiz, Bellot Rubio, Rouppe van der Voort, ApJ (submitted)
Ortiz, Bellot Rubio, Rouppe van der Voort, ApJ (in press)

Rapid temporal evolution of flow field. Lifetimes: a few minutes
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

Magnetoconvection in the penumbra
Scharmer et al., Nature (2002)

Energy transport in thepresence of inclined field?
What’s the structure of thepenumbra?
SST imaging, 0.1" resolution
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

Magnetoconvection in the penumbraScharmer et al., Nature (2002)

Magnetic flux tubes?

Solanki & Montavon, A&A (1993)

MISMAs?

Sánchez Almeida, ApJ (2005)

Field-free gaps?

SST imaging, 0.1" resolution
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Spruit & Scharmer, A&A (2006)

Luis R. Bellot Rubio!

Magnetoconvection in the penumbra

Rempel et al., Science (2009)
Vertical magnetic fieldContinuum intensity

Overturning convection?

• Filaments are hot
convective upflows
deflected radially outward
by inclined sunspot field• Return downflows occur
on either side of thefilaments
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Scharmer et al. (2002)
Radial velocity

Vertical velocity
Luis R. Bellot Rubio!

Magnetoconvection in the penumbra
TRIPPLE @ SST + AO, Fe I 709.0 nm, spot at θ = 5º

Bellot Rubio, Schlichenmaier, Langhans (in preparation)

Slit spectroscopy at 0.2": no overturning downflows larger than 100 m/s!!
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

Magnetoconvection in sunspot penumbrae

Rouppe van der Voort, Ortiz, Bellot Rubio (in prep)• CRISP @ SST + AO, 5 July 2009
• Fe I 630 nm line pair , 17 λ's per line
• 2 hr time series, MOMFBD
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

The temporal evolution is the key tounderstand magnetoconvection inthe penumbra
Scharmer et al. (2002)

Luis R. Bellot Rubio!

Magnetoconvection in sunspot penumbrae

Rouppe van der Voort, Ortiz, Bellot Rubio (in prep)• CRISP @ SST + AO, 5 July 2009
• Fe I 630 nm line pair , 17 λ's per line
• 2 hr time series, MOMFBD
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

The temporal evolution is the key tounderstand magnetoconvection inthe penumbra
Scharmer et al. (2002)

Luis R. Bellot Rubio!

The quiet Sun
Circular polarization

NETWORKLites et al., 2008, ApJ, 672, 1237

• Network delineates supergranular cells

Hinode/SP normal map
Noise level: 1.1 x 10-3 Ic• Strong (kG) vertical fields• Total network flux: ~ 4 x 1024 Mx

3rd Hinode Science Meeting, Tokyo, 1-4 December 2009 !

Luis R. Bellot Rubio!

Ephemeral regions• Small magnetic bipoles• Emerge near the centerof supergranular cells• Early papers:BBSO magnetogram, ± 50 Mx cm-2

Dodson (1953), citing Babcock
Harvey & Martin (1973)
Harvey et al. (1975)• Pole separation: ≤ 20"• Horizontal speed: ~ 4 km/s
• Flux: 1-300 x 1018 Mx• Mean flux: ~ 1019 Mx• Lifetime: ~ 4 hChae et al. (2001)

2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010 !

Luis R. Bellot Rubio!

Ephemeral regions
Hinode/NFINa I D1 589.6 nm
Cadence: 3 min
FOV: 112" x 112"

Bipolar ephemeral regions are large structures formed by small-scale,
mixed-polarity elements
3rd Solaire Network Meeting + FEW 2009, Puerto de la Cruz, 2 Nov 2009 !

Luis R. Bellot Rubio!

Source of network flux
Emergence rate (MDI)• Ephemeral regions are the main
source of flux for the network• Emergence rate: ~106 ERs/day• Flux rate: ~ 1025 Mx/day• Timescale for flux replacement− 40-70 h (Schrijver et al. 1997)− 40 h (Schrijver et al. 1998)− 8-19 h (Hagenaar et al. 2003)− 1-2 h (Hagenaar et al. 2008)

Hagenaar et al., ApJ (2003)
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

Source of network flux
Hinode/NFI, 20 hr time sequence @ disk center• Ephemeral regions are the main
source of flux for the network• Emergence rate: ~106 ERs/day• Flux rate: ~ 1025 Mx/day• Timescale for flux replacement− 40-70 h (Schrijver et al. 1997)− 40 h (Schrijver et al. 1998)− 8-19 h (Hagenaar et al. 2003)− 1-2 h (Hagenaar et al. 2008)

Is the replacement reallythat fast?
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

Local surface dynamo simulations
Danilovic, Schüssler, Solanki, A&A (2010)

SimulationDegraded simul.

Hinode/SPContinuum

Vertical flux

Transverse flux

General agreement, but field too weak by a factor 3. Temporal evolution?
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

Magnetic coupling: flux cancellation events
TIP+POLIS @ VTT, + DOT
Verticalflux

G-bandCa II HTime (Δt=7min)

Bellot Rubio & Beck, ApJL (2005)• Duration: minutes to hours• Action occurs in thin contact line, but the two patches are affected• Spatial resolution required: ~ 0.1"
• Multiwavelength observations, to follow process in different layers

2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

Magnetic coupling: flux cancellation events
Zwaan, ARAA (1987)

Cancellation of opposite polarities
can be interpreted as:a) Flux retractionb) Ascent of U-loopc) Submergence of Ω-loop

Processes (b)-(c) involve
magnetic reconnection andmay have consequences forchromosphere

2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

Magnetic coupling: small-scale loops in the IN
Centeno et al. 2007
Martínez González & Bellot Rubio 2009; Ishikawa et al. 2010

Hinode/SP, 25 Sep 2007

IcTLP

TCP

Magnetic loops emerge in the internetwork on granular scales, showing
linear polarization signal in between two-opposite polarity footpoints
3rd Hinode Science Meeting, Tokyo, 1-4 December 2009 !

Luis R. Bellot Rubio!

Magnetic coupling: small-scale loops in the IN

CN intensity

Magn flux (Fe I)

Magn flux (Mg I b)

MartínezGonzález& Bellot2009,
ApJ,
700, 1391
3rd Hinode
Science Meeting,Tokyo,Rubio,
1-4 December2009!

Ca II H intensity

Luis R. Bellot Rubio!

Magnetic coupling: small-scale loops in the IN
Martínez González et al., ApJL(submitted)• 69 events in 28 hr• FOV: 2.7" x 41"• Flux: 9 x 1016 Mx• Flux density: 25 G
• Max separation: ~2"• Lifetime: ~12 min• Vertical velocity: 3 km/s

Important source of flux for the IN: ~ 1024 Mx/day in the entire Sun
About one quarter of the loops reach the chromosphere.
Downflows and Ca II H brightenings at those heights: signature of heating?
3rd Hinode Science Meeting, Tokyo, 1-4 December 2009 !

Luis R. Bellot Rubio!Magnetic coupling: complex Stokes profiles++Quiet Sun at disk center
25 Sep 2007
Hinode/SP
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010 !

Exposure time:
Pixel size:
FOV:
Cadence:

1.6 s/slit
0.16ʺ″
2.9ʺ″ x 40ʺ″
30 s
Luis R. Bellot Rubio!

Magnetic coupling: complex Stokes profiles
Sainz Dalda, Title, Bellot Rubio

One-lobed Stokes profiles are associated with strong flows
Origin and effects on chromosphere?

2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

Magnetic coupling: complex Stokes profiles
de Pontieu et al., ApJL (2009)

One-lobed Stokes profiles are associated with strong flows
Origin and effects on chromosphere?

2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

What do we need to solve these problems?
Excellent stability
Uninterrupted observations (hours-days)
Access to chromosphere, TR, and corona
PLUS
Spatial resolution of ~0.1"
Excellent throughput (fast cadence)

2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!

What can SOLAR-C offer us?
Excellent stability
Uninterrupted observations (hours-days)
Access to chromosphere, TR, and corona
PLUS
Spatial resolution of ~0.1"
Excellent throughput (fast cadence)(with 1.5m telescope)
2nd Solar-C Science Definition Meeting, Tokyo, 11 March 2010!

Luis R. Bellot Rubio!