OISTERと連携した
矮新星アウトバースト観測
Y. Tampo (Kyoto U.)
T. Kato, D. Nogami
K. Isogai, N. Kojiguchi,
Y. Wakamatsu (Kyoto U.),M. Kimura (Riken)& on behalf of VSNET team©NASA

OISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTERDN observations w/ OISTER
2018
・矮新星ASASSN-18yiの食の観測 (PI: 若松)・軌道周期3時間以上のSU UMa型矮新星の可視赤外・分光観測 (PI: 若松)→ Wakamatsu et al., 2021 PASJ
2019
・WZ Sge型矮新星のアウトバースト中の近赤外線モニタリング (PI: 木邑)→ Kimura et al., 2021 PASJ・矮新星アウトバースト中の可視分光モニタリング：円盤風由来の線スペクトルの検出 (PI: 木邑)
・低振幅/低頻度のアウトバーストを示す長周期矮新星の可視分光観測 (PI: 木邑)
2020
・連続測光分光観測による矮新星静穏期の降着円盤の再構成 (PI: 反保)*** some other proposals on X-ray binaries by Kimura-sanOISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

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Today’s contents
1, Introduction of dwarf nova outbursts
2, An eclipsing SU UMa-type CV w/ a 3.6 hr orbital period: Wakamatsu et al., 2021
3, Multi-wavelength photometry of EG Cnc 2018 superoutburst: Kimura et al., 2021
4, Accretion disk structure and evolution during the quiescence of DNe: OISTER observation, PI Tampo
5, Summary

OISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

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Cataclysmic variables: 激変星

Roche lobeを満たした伴星と降着する白色矮星の近接連星系
Classical Novae: 古典新星
: WD表面での熱核暴走反応
Nova-like stars: 新星状天体: 円盤の明るさが卓越したCV(intermediate) Polar: 強磁場激変星: WDの磁場が強く (~10^6 G)，円盤(の内側)がくり抜かれている
Dwarf Novae: 矮新星

Abril+2020→ 詳しくは，磯貝さんのOISTERセミナースライドへ。

OISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

4矮新星と円盤不安定モデル

円盤の光度変化による突発現象: 円盤の変動を調べる格好の対象
DN outburstのメカニズム: 水素ガスの電離に伴う降着円盤の状態遷移
Osaki1974, Meyer+1983

Kato&Osaki2013
week ~ decadea few
magdays ~ monthOISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

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Porb vs. Mass Transfer Rate

©Kepler©Kepler

OISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

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Today’s contents
1, Introduction of dwarf nova outbursts
2, An eclipsing SU UMa-type CV w/ a 3.6 hr orbital period: Wakamatsu et al., 2021
3, Multi-wavelength photometry of EG Cnc 2018 superoutburst: Kimura et al., 2021
4, Accretion disk structure and evolution during the quiescence of DNe: OISTER observation, PI Tampo
5, Summary

OISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

7Superhump
Psh = +3% of Porb

Superoutbursts in DNe
円盤が3:1共鳴半径に達することが条件
Whitehurst+1988*** 軌道周期とケプラー円盤の共鳴→ 伴星からのより効果的な潮汐的作用→ Brighter & longer outburst !
(Superoutburst = SU UMa-type DNe)
これを満たすには…
3:1 共鳴半径 < tidal truncation R (円盤外縁の限界)→ mass ratio (q=Msec/Mwd) < ~0.3
→ Porb < 2hr を満たすことが必要

Tidal Truncation R

Porb > 2hrでもsuperoutburstを見せる天体も。
これらも同じ3:1共鳴による現象なのか？
e.g., Mennicket 1995

3:1 Resonance

OISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

8ASASSN-18aan
Porb ~ 3.6 hr: 典型的なSU UMa starsよりも長い0.5等の食を持つ→ 食の形状から円盤半径を見積もれる !
→ 本当に3:1共鳴半径に達しているのか?

credit: Wakamatsu-sanOISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

9ASASSN-18aan
Kato&Osaki 2013
PorbとPshから...
→ mass ratio = 0.278(1), despite of long Porb
← 伴星が進化し，Roche lobeを満たす

静穏期のモデリングとRadial velocityから，→ inclination = 76.60(9)食の形状を半径をパラメータにモデリング→ 円盤半径が3:1共鳴半径に到達している !
→ ASASSN-18aanでも，3:1共鳴がメカニズム@Nayuta

OISTER data*** >15 magの深い連続測光観測← 30cmクラスの望遠鏡では厳しい等級*** Nayutaの分光で，水素輝線を確認← 円盤が実際に明るくなっていることを確認

credit: Wakamatsu-sanOISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

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Today’s contents
1, Introduction of dwarf nova outbursts
2, An eclipsing SU UMa-type CV w/ a 3.6 hr orbital period: Wakamatsu et al., 2021
3, Multi-wavelength photometry of EG Cnc 2018 superoutburst: Kimura et al., 2021
4, Accretion disk structure and evolution during the quiescence of DNe: OISTER observation, PI Tampo
5, Summary

OISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

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Rebrightening: 再増光
アウトバーストで円盤内のガスがWDに降着→ アウトバースト後に円盤へのガス供給が必要
Hameury+2000
Enhanced Mass Transfer
照射され膨らんだ伴星から輸送流が増加
Kato+1988, Osaki+2001
Mass Reservoir
円盤外縁部にガスが残り降着してくる
アウトバースト後の赤外超過が証拠？

Kimura+2021

Patterson+1988, Matsui+2008, Neustroev+2018

OISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

12EG Cnc“King of Echo Outburst”

Patterson+1998

2018アウトバーストの再増光パターン: 1996アウトバーストと酷似
Kimura+2016: 天体に固有? (mass ratio)

Kimura+2021

再増光のメカニズムを調べたい: 多波長での測光観測モニター: 赤外超過がどのように変化していく？
Optical & IR

UV & X-ray

VSNET

multi-color

SaCRAr, i, z

KanataRc, J, Ks

MITSuMERc, IcSwift XRT & UVOTOISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

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Rebrightening in multi-wl 1.
Rising redder t/ fading in B-I
Bailey 1980
: アウトバーストの典型的なパターン: 内側がhotになるまで時間がかかる
Unusual red colour (B-I ~ 0.8)
after main outburst b/w rebrightenings: 低温なmass reservoirの存在を示唆 ?

Bailey 1980
Blue

Patterson+1988, Matsui+2008, Neustroev+2018

Gradually getting bluer in B-I & J-Ks
across the rebrightening: rebrigheting毎にmass reservoirが減少していくことに対応?

RedBlue

OISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTERRed
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Rebrightening in multi-wl 2.
X-ray: faint during the rebrightening← boundary layerが光学的に厚い状態
UV: resemble to optical light curve← inner diskからの放射を反映している
Bailey 1980
U-B: as red as DN quiescence← rebrightening毎に，円盤内側までcoolな状態になっている← Rebrighteningは急な増光でスタート→ Rebrightening毎に，円盤外側からheating waveが走ってoutburstになる[inner diskで跳ね返される訳では無い]
Meyer+2015

OISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

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Today’s contents
1, Introduction of dwarf nova outbursts
2, An eclipsing SU UMa-type CV w/ a 3.6 hr orbital period: Wakamatsu et al., 2021
3, Multi-wavelength photometry of EG Cnc 2018 superoutburst: Kimura et al., 2021
4, Accretion disk structure and evolution during the quiescence of DNe: OISTER observation, PI Tampo
5, SummaryOISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

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矮新星静穏期の長期変化
From Gaia & ZTF deep survey data...
gradual brightening & reddening
YT+2020
before outbursts of V3101 Cygoutburst⇒ ﬁrst ever observed, but seems to becommon feature in short Porb DNe?
⇒ time scale of week ~ decade⇒ evolution of disk structure?

YT+20201) surveys can give a statistical view2) wanna conduct long-term& detailed study in a single systemfrom Kojiguchi-sanOISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER17

2 ways to study disk structure
Doppler tomography
Marsh&Horne1988: reconstruct the line emissivity
from each velocity component⇒ hot spot, disk asymmetry⇐ using Seimei KOOLS-IFU VPH683
Eclipse modeling/mapping
Horne1985: modeling eclipse of a disk
by secondary star⇒ disk Temp, Radius, hotspot⇐ using MITSuME & TriCCS

McAllister+2019

Skidmore+2000

OISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER18

Today’s contents
1, Introduction of dwarf nova outbursts
2, An eclipsing SU UMa-type CV w/ a 3.6 hr orbital period: Wakamatsu et al., 2021
3, Multi-wavelength photometry of EG Cnc 2018 superoutburst: Kimura et al., 2021
4, Accretion disk structure and evolution during the quiescence of DNe: OISTER observation, PI Tampo
5, Summary

OISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

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Multi-mode obs. in CVs
SurveyVSNET
長期間のトレンド

アウトバースト
連続測光
静穏期 アウトバースト
多色測光
連続測光
snap分光アウトバースト
連続分光
OISTER & Seimei

赤外線モニター観測新規
アウトバーストの検出

Kepler, TESSUV＆X線観測静穏期連続分光OISTER workshop 2021, 25th Oct. 2021, Y. Tampo, DN observations w/ OISTER

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