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ASO-S Mission:

current status and early results

Yang Su, Li Feng, Lei Lu (presenter)

ASO-S team

Purple Mountain Observatory, CAS

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PASW ● 2025-03-27 ● Wuhan

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Outline

  • ASO-S mission and three payloads
  • ASO-S observations
  • ASO-S selected Early results

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ASO-S: mission overview

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  • The Advanced Space-based Solar Observatory (China’s first comprehensive solar mission)

Orbit: sun-synchronous

Lifetime: ≥ 4 years

“夸父一号”

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ASO-S: spacecraft and three payloads

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Scientific objectives: ‘1M2B’ – Magnetic field and two Bursts (flare and CME)

HXI : Hard X-ray Imager

FMG: Full-disk MagnetoGraph

LST: Lyman-alpha Solar Telescope

LST

FMG

HXI

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FMG and HXI: key instrumental parameters

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FMG specifications

Diameter

140 nm

FoV

33.67’

Spatial Resolution

1.04’’

Spectral line

Fe I 532.4 nm

FWHM of filter

0.01014 nm

Time cadence

~2 mins

Pointing accuracy

≤ 0.25′′

HXI specifications

energy range

~ 10 -300 keV

Spatial resolution

~ 3.1’’

Energy resolution

~ 16.5%@32keV

Time cadence

0.125 – 4s

Grid pitch

10 groups from 36 to 1224 μm

Pointing accuracy:

Better than 0.3’’

Time resolution: 0.25 s

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LST: key instrumental parameters

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LST instruments

WST: White-light Solar Telescope

SDI: Solar Disk Imager

SCI: Solar Corona Imager

Lyman-alpha Solar Telescope (LST)

SCI

WST

SDI

parameters

WST

SDI

SCIUV

SCIWL

waveband

360±2nm

121.6±4.5nm

122.6±3nm

700±32nm

FOV

0 – 1.2 Rs

0 – 1.2 Rs

1.1 - 2.5 Rs

1.1 - 2.5 Rs

Image size

4608×4608

4608×4608

2048×2048

2048×2048

cadence

routine (2min)

burst (1s & 2s)

user defined

routine (1min)

burst (a few s)

user defined

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Li+(2019) RAA Chen+(2019) RAA

Feng+(2019) RAA

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Outline

  • ASO-S mission and three payloads
  • ASO-S observations
  • ASO-S selected Early results

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ASO-S Observations: FMG

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  • FMG can only measure longitudinal component of magnetic fields
  • FMG lacks routinely full-disk measurement

SDO/HMI

ASO-S/FMG

LoS magnetogram

  • Left is a subregion observed by HMI.
  • Right is the same region observed by FMG.
  • They are almost identical.

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ASO-S Observations: FMG

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ASO-S/FMG May 5-7

Extremely complex magnetic field configuration and photospheric evolution

spaceweather.com

sunspot area is comparable to Carrington event, series of X-class flares occurred

the super active region 3664

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ASO-S Observations: HXI

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  • HXI spectroscopy + imaging (10 -300 keV)
  • Its performance is exactly the same as or even better than that designed

Fine structures in hard X-ray emission at flare ribbons, post-flare loops, and loop tops

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ASO-S Observations: HXI

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ASO-S/HXI

HXI dynamic spectra for major flares occurred in a 10-day time window in May 2024.

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ASO-S Observations: HXI

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ASO-S Observation Examples: HXI

Comparison between HXI and STIX carried by Solar Obiter (20o separation angle, 0.62 AU)

SO

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ASO-S Observations: LST

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  • LST provides full solar disk and inner corona images in Ly𝛼 and WL simultaneously.

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  • Unfortunately, the spatial resolution of disk images are not as expected.

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  • The stray light levels of WL coronagraph is a little bit high, but still observed quite a few CMEs

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LST observations

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WST

SDI

SCIWL

SCIUV

CME related to X5 flare � on Dec. 31 2023

SCIWL

SCIUV

SCIWL

SDI

Composite movie from SDI, SCIWL & SCIUV, showing an CME eruption with a beautiful prominence as its core in WL and Lya.

SDI

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Prominences observed by SCIUV

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Series of CMEs observed by SCIWL

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20240509 X1.1

20240510 X4.0

20240511 X5.8

20240514 X8.7

20240515 X3.5

20240515 X3.0

20240514 X1.7

20240527 X2.7

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Composite image of SCIWL, SUVI, LASCO/C2

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SCIWL

SUVI/284 A

LASCO/C2

SCIWL

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Outline

  • ASO-S mission and three payloads
  • ASO-S observations
  • ASO-S selected Early results

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ASO-S：Early Results

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Solar WL flares: occurrence and emission properties

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Jing+ 2024, SoPh, Editor’s Choice

  • Statistical Study: Solar WL flares at 360nm are NOT rare --- occurrence probability is 24% (2022-2023, higher in the solar maximum year)
  • An important reference for stellar flare studies

205 (49) > M1

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Solar WL flares: occurrence and emission properties

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Li Ying+ 2024, ApJL, 963, L3

  • Two case Studies: the Balmer continuum radiation in a solar WL flare comes not only from flare ribbons but also flare loops.
  • Providing critical constraints for modelling flare energy transport and deposition.

X2.1

X1.5

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First Carrington map in Ly-alpha

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a key for computing Ly-alpha emission in corona.

Li, S. + 2024, ApJ Letters

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Qusi-periodic oscilations (QPP)

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  • QPP studies based on HXI and multi-band observations （Li+ 2023 AA Letter, Li+ 2024 ApJ, Shi+2024 SoPh）
  • Intrinsic connections between flare-driven weakly-damped coronal loop oscillations, the origin of flare QPPs, and particle acceleration
  • A complete study from observations to simulations for QPP and particle acceleration（Chen+, prep for NA)

QPP and source

motion

MHD simulation

Particle acceleration

and propagation

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The first 3D diagnosis of HXR sources (STIX & HXI)

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Joint diagnosis of an M1.5-class flare (SOL20230208)

The real 3D structure of flare HXRs

Mrozek+2024, Solar Physics

Collaboration via ASO-S

Guest Investigator Program

STIX

HXI

31.5o

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Coordinated observations between SCIWL and DART

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SCIWL

SCIWL

06:55:56

06:56:56

06:57:56

06:58:56

06:53:56

06:54:56

Lu, et al., in prep

CME and radio sources

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Ly𝜶 radiation in CMEs and prominences

  • ASO-S/LST has observed quite a number of CMEs, prominences, etc.
  • How do we obtain the disk Ly𝜶 emission as seen by a coronal neutral hydrogen atom? SDI Carrington map（Li,S.+2024, ApJL）
  • How does the Ly𝜶 emission in the corona depend on the disk Ly𝜶 emission, geometric function, temperature assumption?

Mostly sensitive to temperature assumption (Ying+2024, SoPh)

  • Are the eruptive prominences optically thick or optically thin in Ly𝜶?

They may evolve from optically thick to thin (Zhao+2022, A&A)

  • How do we diagnose the prominence parameters using Ly𝜶 observations?

Ly𝜶+WL, Ly𝜶+H𝜶, Ly𝜶+30.4nm, NLTE radiative transfer…

(Zhang+2024, Xue+2024, Li,S.+2025, in prep)

  • How do we diagnose the CME parameters using Ly𝜶 observations?

Ly𝜶+WL (Ying+2020, ApJ, Bemporad+2024, ApJ)

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ASO-S data and software

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http://aso-s.pmo.ac.cn/english/science/asos_gip.jsp

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AGIP program has supported 8 visitors since 2023.10.

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Thank you very much for your attention