光赤天連シンポジウム2019
2019/09/25 @NAOJ

Ultraviolet Space Telescope
forAstronomy and Planetary Science
Go Murakami1, Shingo Kameda2, Masami Ouchi3, MasaomiTanaka4, Norio Narita5, Fuminori Tsuchiya6, Tomoki Kimura6,
Kazuo Yoshioka7, and Atsushi Yamazaki1
1JAXA/ISAS, 2Rikkyo Univ., 3Institute of Cosmic Ray Research,
4ABC, 5Tohoku Univ., 6Univ. TokyoUV technique in solar system science:
our heritages
Kaguya/UPI-TEX (2007-2009)

Io’s volcanic activity detected by Hisaki
Io’s volcanic plasma (Sulfur ions)
Earth’s hydrogen corona

Hisaki/EXCEED (2013-)

BepiColombo-MPO/PHEBUS (2018-)
PROCYON/LAICA (2014-2015)

EQUULEUS/PHOENIX (2019-)

ISS-JEM/IMAP-EUVI (2012-2015)

Goal 1: Ocean worlds and plasma environments of Jupiter/Saturn system(1) First-ever continuous monitoring of the water plumes erupted from icy moons(2) Long-term monitoring of energy flows in gas giants’ magnetosphere➔ High sensitivity and high spatial resolution UV spectroscopy by Japan’s “own” telescopeYear[Roth et al., 2014]

Jupiter

20

JUNOUVDec 2012

19Hisaki2122232425262728

EuropaClipper

WSO-UV29303132JUICEUVST?

HSTJWSTIRGanymedeNov 2012

OpticalOct 1999

18

Outer planetexploration

Water plumes: When? How often?

Space telescope

EuropaAuroral morphology reflects
magnetospheric dynamics-> Energy flows to icy moons[Feldman et al., 2002]-Spectral range: 120-160nm with <1nm resolution-Spatial resolution: 0.1 arc-sec-Effective area: >200cm2-Field of view: >320 arc-sec

Goal 2: Characterization of Earth-sized exoplanets
UV transit observation to detect extremely expanded Oxygen exosphere➔ Distinguish Earth-like planets from Mars-/Venus-like planets
Proxima Centauri[10 ] 4-14

Flux, erg/cm2/s/Å

HZ of cool star: close to star -> High UV irradiation (> x10)
Venus-likeEarth-like

32Before transit
During transit (Earth)
During transit (Venus)

Transit depth:
24%!

10300,000 km

1305.9Black: Planet

White: Star

1306

1306.11306.2

Wavelength, Å

300,000 km

Only the Earth-like planet has

extended oxygen corona-Spectral range from <120nm to >135nm(H Ly-α: 122nm, OI: 130nm)-Spectral resolution: <0.3nm-Sensitivity stability: <1%4Goal 3: First Atlas of Gaseous Large-Scale Structures(1) What is the baryonic structure of the universe today?
(2) What happened at the beginning of the universe? How did our MW form?
➔ Combination of Lyα intensity, emitters, and absorptions of backgrounds---Cosmology and Galaxy Formation Astronomy--3) Lyα Absorbers

Credit: Khee-Gan Lee (MPIA)
and Casey Stark (UC Berkeley)2) LAEs

Baseline survey: >1000 deg2 to ~24 mag
1) Lyα Intensity- Imaging with a spatial res. of ≲ 10”2) Lyα emitters (LAEs)- Imaging/slitless spec (≲ 4” & R ≳10)
Credit: NASA / ESA / Hubble / 3) Lyα Absorbers
ESO / Lutz Wisotzki et al.
- Slitless/target spec (R ≳10/100)

1) Lyα Intensity

Non-Gaussianity measuremens for determining inflation models

StarsGalaxies inGaseous Large-Scale Structures c)http://spherex.caltech.e
Credit:Matt Hayes

du/Science.html#Inflation

Goal 4: Time-domain astronomy(1) How are relativistic jets formed in extreme physical environment?
(2) What happens in the last 10 years of stellar evolution?
➔ Detecting the first 1 hour of explosive transients in UV(1) UV survey for GW source- 23 mag (AB) depth for 100 deg2
within 1 hour
- Rapid data transfer to the ground

Jet

Neutron starmerger(C) ESA

Gravitational
Wave (GW)GW170817

Alert

Multi-messenger
astronomy(C) NAOJ/Nagoya U.

(C) KAGRA(2) UV survey for supernovae- 23 mag (AB) depth for 100 deg2
- 1 hour cadenceFuture plans and roadmaps<Key techniques>-Analyze each requirement-Detector-Concept study of the telescope system and instruments-Two designs: for S-class and M-class-Clarify the key techniques for this mission and future
TargetGoal 1Goal 2Goal 3

Goal 4

Icy moons

Exoplanets

Gaseous

GW/supernovae

Slitless
Mode

Imaging/spectroscopy Spectroscopy(/Imaging)slitless

Imaging

spectroscopy

Spectral range

120-160nm

120-135nm

120-190nm<300nm?

Spectral resolution<1nm<0.3nmTBD

TBD

Spatial resolution<0.2 arc-sec

-TBD

TBD

Field of view>320 arc-sec->0.3 deg2

100 deg2, 23

Effective area>200 cm2>200 cm2

TBD

Mag(AB) in 1h

UV space telescope with high sensitivity (>1m class)-Lightweight mirror-Tip-tilt/defocusing mechanism

Demonstrations for Japan’s space telescope design/development
Participations to large missions (LUVOIR/HabEx)