Multi-wavelength Studies of stars andcompact objects in light of LAMOST+

A progress report
Jifeng Liu（NAOC/UCAS）
Yu Bai, Song Wang, Qing Gao、Huiqin Yang、Lin He
EAYAM2017 – 2017/11/17

Stars and compact objects: Questions① Stellar
activities
Formationof SN Ia

White Dwarf②⑤

Formation ofBlackholes④
EOS of NS？

Black Hole
Neutron star③
space-timearound BH:
accretion

Formation/growthof supermassive BH! ULX？

Stars to black holes: Challenges!
Observations Miss light black holes?

Theory Misses heavy black holes?

Urgently needed: Black hole mass distribution
with statistical significance!
vSelect a large sample of black hole binary candidates
vMeasure the dynamical masses via monitoring campaign

Our approach: Big Data w/ LAMOSTROSAT All-Sky Survey⑤④③⑥GALEXKepler

②
X-ray

①>9Millon stellar spectra
Gaia

radio

qStatistical studies of stars
qExotic objects
qIdentification of compact objects

I: UV radiation from stars
A catalog of 3millon stars
qLAMOST+GALEX+WISE
qExtinction estimates: RJCE
(Bai, Liu et al, 2017 ApJS in revision)

UV dominated by photosphere

Young F/G stars?
Or Binaries?

Future work:

Stellar variability:
multiple observation
photon-counting light curves
Origin of UV-upturn?
UV excess of late-type stars?
Helium stars?

UV dominated by chromosphere
Red dots: spectra from SDSS

II: X-ray radiation from stars
X-ray binaries?
FGLog(g)KM
Fx/Fo
LAMOST+XMM-Newton(He, Liu et al. in preparation)

Teff (K)II: X-ray radiation from stars

Fx/Fo“young”“old”

Teff (K)Less active subpopulation
LAMOST+XMM-Newton(He, Liu et al. in preparation)higher metalicity:younger?

III: Be stars caught in action

Be: B stars with emission linesàgaseous disk around B stars

But how does the disk form?

III: Be stars caught in action

III: Be stars caught in action

disk signature：rms - flux correlation

III: Be stars caught in action
Outbursts
driven by beatingIII: Be stars caught in action

Outbursts/BeatsP ~ 50days

III: Be stars caught in action
Lowerfrequencies!

III: Be stars caught in action
Lowerfrequencies！

（高清+2017）

What does this frequency change tell us?

IV: stellar activity of M dwarfs
Turbulent
dynamoKepler data

Flares:magneticreconnection
Stellar spots(magnetic field)+Rotation

Yang, Liu et al. 2017, submitted to ApJS

100K flares from 540/4664M dwarfs

IV: stellar activity of M dwarfs
Whymost stars withthe same Logg,Teff, period,
spot amplitude
do not haveflares?

Energetic flares, but no period detected!
shorter period, larger stellar spots, stronger flares

Puzzles!

Future work

stellar activities across HR diagram
Variety of activitiesØPulsationØNon-radial pulsationØRotation w/ spotsØBinarityØFlaresa uniformly processed database @ AliCloud
200K Kepler targets +LAMOST etc
Physical parametersØPeriods and harmonics à shapesØSigma8 à gravity etcØPeriod deriatives à stellar cyclesØBeating frequencies

à Activity versus Inactivity

Future work

X-ray binaries from RASS

Contamination from QSOs and Galaxies

AGN/QSO：~halfStars：~half
X-ray binaries: a few percent à 102~104（董一泽、白宇+）Future work

Mass function for BH/NSs
X-ray binaries
Newly foundA dedicated integrated imaging spectrograph
To be mounted on a 4m telescope by 2019

Stay tuned …

Welcome to join

Prof Stephen Justham

UCAS

Prof. Roberto Soria

Prof Jifeng Liu

Tenure-track faculty at NAOC/UCAS
Staff researcher in our group
Postdoc: PIFI fellowships etc
Long-term or short-term visitors