norio narita (naoj) on behalf of ird transit group

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Transiting Exoplanet Search and Characterization with Subaru's New Infrared Doppler Instrument (IRD) Norio Narita (NAOJ) On behalf of IRD Transit Group

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Transiting Exoplanet Search and Characterization with Subaru's New Infrared Doppler Instrument (IRD). Norio Narita (NAOJ) On behalf of IRD Transit Group. Outline of This Talk. Searching new transiting planets around cool host stars before and after IRD’s first light - PowerPoint PPT Presentation

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Page 1: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Transiting Exoplanet Search and Characterization with Subaru's New Infrared Doppler Instrument (IRD)

Norio Narita (NAOJ)On behalf of IRD Transit Group

Page 2: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Outline of This Talk

1. Searching new transiting planets around cool host

stars before and after IRD’s first light

2. Characterizing new transiting planets with IRD and

other telescopes / instruments

Page 3: Norio Narita (NAOJ) On behalf of  IRD Transit Group

How to Find Transiting Exoplanets

• RV detection and transit follow-up

– HD209458b, HD189733b, HD149026b…

– GJ436b, GJ3470b…

– How many transiting planets can be discovered with IRD?

• Transit survey and RV follow-up

– TrES, HAT, WASP, XO, CoRoT, Kepler, MEarth…

– GJ1214b, Kepler planets

Page 4: Norio Narita (NAOJ) On behalf of  IRD Transit Group

The First Discovery of a Transiting Planet

Charbonneau et al. (2000)

Transits of HD209458bMazeh et al. (2000)

RVs of HD209458b

RVs can predict possible transit times

How often does it happen?

Page 5: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Some Characteristics of Transiting Planets

stellar radius :

planetary radius :

Toward Earthsemi-major axis :

orbital period :

Transit Probability :

Transit Depth :

Transit Duration :

~ Rs/a

~ (Rp/Rs)2

~ Rs P/a π

Page 6: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Transit Probabilities for IRD Targets

• IRD’s main targets are M dwarfs

• Bonfils et al. (2011) reported results of HARPS RV

survey for M dwarfs that super-Earths are frequent

– P = 1-10days : f=0.36 (+0.25, -0.10)

– P = 10-100days : f=0.35 (+0.45, -0.11)

– If IRD monitor ~200 M dwarfs, IRD can find ~70 super-

Earths

Page 7: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Transit Probabilities for M0V & M6V

• M0V– Rs ~ 0.62 Rsun ~ 0.00288 AU

– P = 100 days -> a ~ 0.334 AU, Transit Probability : Rs/a ~ 0.86%

– P = 10 days -> a ~ 0.072 AU, Transit Probability : Rs/a ~ 4%

– P = 1 days -> a ~ 0.0155 AU, Transit Probability : Rs/a ~ 18.5%

• M6V– Rs ~ 0.1 Rsun ~ 0.000465 AU

– P = 100 days -> a ~ 0.195 AU, Transit Probability : Rs/a ~ 0.24%

– P = 10 days -> a ~ 0.042 AU, Transit Probability : Rs/a ~ 1.66%

– P = 1 days -> a ~ 0.009 AU, Transit Probability : Rs/a ~ 7.75%

Page 8: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Expected Number of IRD Transiting Planets

• Transit probability for P = 100 days is too low

• For P = 1-10 days, probability is not bad (several %)

– IRD aims detections of ~70 planets by RV method

– If 70 super-Earths at P = 1-10 days are discovered around

M dwarfs, there would be a few new transiting planets

• Planets with P = 1-10 days can be habitable around

M5-6-type dwarfs

Page 9: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Ongoing/Future Transit Surveys around M Dwarfs

• Transit surveys before IRD’s first light

– MEarth (Harvard) and other teams in the world

– SEAWOLF survey (UH/NAOJ/etc)

– MOA-II transit survey (NAOJ/MOA)

• Future Space-based Survey with IRD follow-up

– TESS from 2017 (MIT/NASA)

Page 10: Norio Narita (NAOJ) On behalf of  IRD Transit Group

SEAWOLF Survey

• Transit survey using Super-WASP

archive data and Lepine & Gaidos

M dwarf catalog

• High precision transit follow-up by

northern hemisphere telescopes

• IRD transit group used Okayama

1.88m telescope in Japan

• Unfortunately no detection, but

constrain the occurrence rate of

hot Neptunes around late-K & M

stars as 5.3 ± 4.4 % (Gaidos+ 2013)

target distribution

occurrence rate

Page 11: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Transit Survey for nearby M dwarfs by 1.8m MOA-II

•Nearby (J<11) M dwarfs are sparsely distributed

in the sky (~1/deg2)•High photometric precision (~1mmag) is required

to detect super-Earths/Neptunes

Wide FOV, 2m class telescope is ideal

The MOA-II telescope in New Zealand• 1.8m mirror• 10 x CCD (2k x 4k)• 2.2 deg2 FOV• Dedicated for planetary microlensing survey during winter (Mar. – Oct.)

Started transit survey during summer season from 2013 Nov(PI: A. Fukui).

the MOA-II telescopeprime-focus camera

Page 12: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Transit Survey for nearby M dwarfs by 1.8m MOA-II

• Selected 6 fields among -20° < Dec. < -5° ; each contains ~10 bright (J < 11) M dwarfs• One field is taken 10 times in a row with a cadence of 80 sec

The selected fields

Expected yields• Can detect planets showing > 0.2 % transit depth from several years survey • Kepler detected 22 candidates showing >0.2% transit depth among 3600 M dwarfs• ~0.4 planets/several years can be detected among our targets (total 65 M dwarfs) -> similar to MEarth survey• monitoring stellar activity for IRD targets

Galactic plane

Example of defocused target images

Field selection/observations

Page 13: Norio Narita (NAOJ) On behalf of  IRD Transit Group

All-Sky Transit Survey: TESS

Led by MIT/NASA and will be launched in 2017

2 IRD science members are participating in TESS Science Working Group

Page 14: Norio Narita (NAOJ) On behalf of  IRD Transit Group

TESS and IRD

• Targets

– Bright nearby stars with I = 4-13 mag (FGKM stars)

• Period of detectable planets

– typically less than 10 days (26-day monitoring for 1 field)

– up to ~60 days for JWST optimized fields

– Planetary orbits with less than 10 (60) days period lie in

habitable zone around mid (early) M stars

– expected to discover ~500 Earths / super-Earths and

Subaru IRD will contribute for RV follow-up of M dwarfs

Page 15: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Outline of This Talk

1. Searching new transiting planets around cool host

stars before and after IRD’s first light

2. Characterizing new transiting planets with IRD and

other telescopes / instruments

Page 16: Norio Narita (NAOJ) On behalf of  IRD Transit Group

What can we learn from transits and RVsRVs provide

minimum mass: Mp sin I

eccentricity: e

Transits provide planetary radius: Rp

orbital inclination: i

Combined information provides planetary mass: Mp

planetary density: ρ

Page 17: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Mass-Radius Relation for “Super-Earths”

Future transit surveys and

IRD can fill this figure out.

Theoretical models can

predict mass-radius relation

for a variety of bulk

compositions, but models

are often degenerated.

How can we discriminate

compositions?

Courtesy of M. Ikoma

Page 18: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Transmission Spectroscopy

star

Transit depths depend on wavelength reflecting atmospheres

Page 19: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Differences of Super-Earths’ Transmission Spectra

Super-Earths’ atmospheric compositions are also important to learn origins of them -> cf. M. Ikoma’s talk

Courtesy of Yui Kawashima

Page 20: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Testing Planet Migration Theories

• Transiting planets are useful to test planet migration theories by orbital eccentricity and obliquity– Population synthesis for small planets around M dwarfs

can predict distributions of such parameters

• IRD can measure both orbital eccentricity and obliquity by RV observations – obliquity by the Rossiter-McLaughlin effect

– We can provide new information to theorists

Page 21: Norio Narita (NAOJ) On behalf of  IRD Transit Group

The Rossiter-McLaughlin effect

the planet hides the approaching side→ the star appears to be receding

the planet hides the receding side→ the star appears to be approaching

planet planetstar

When a transiting planet hides stellar rotation,

radial velocity of the host star would havean apparent anomaly during transits.

Page 22: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Observable Orbital ObliquityAre there any tilted or retrograde super-Earths?

λ : sky-projected angle betweenthe stellar spin axis and the planetary orbital axis

(e.g., Ohta et al. 2005, Gaudi & Winn 2007, Hirano et al. 2010)

Page 23: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Merit of IRD for the RM study

• M dwarfs are very faint in visible wavelength

• Measurements of the RM effect need enough time-resolution

and RV-precision

• Actually, GJ436 (V=10.6, J=6.9), GJ1214 (V=14.7, J=9.8),

GJ3470 (V=12.3, J=8.8) are quite difficult targets with the

current visible instruments

• IRD can significantly improve time-resolution and enable us to

determine λ for those planets

• We can test predictions of planet population synthesis

Page 24: Norio Narita (NAOJ) On behalf of  IRD Transit Group

Conclusion

• IRD transit group is working on transit-related

science cases for Subaru IRD

• Subaru IRD will be useful for both searching and

characterizing new transiting super-Earths