Lea Hirsch, Stanford University

Elise Furlan, NExScI-Caltech/IPAC

Mike Lund, NExScI-Caltech/IPAC

CPS Team, Kepler FOP Team, TESS FOP Team

AT LAST! CONFIRMATION OF KEPLER'S SECOND PLANETARY CANDIDATE DAVID R. CIARDI

NASA EXOPLANET SCIENCE INSTITUTE CALTECH/IPAC

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

EXOPLANETS IN MULTI-STAR SYSTEMS• Nearly half of stars in the solar neighborhood have stellar

companions, but less than 10% of the known exoplanetary host systems have stellar companions• Stellar companions may (partially) quench or change planetary

formation and evolution processes• Discovery and characterization studies tend to avoid multi-star systems

• Little is known about the properties of planetary systems in single vs multiple star systems

2021 January 11AAS 237 2

This is the (abbreviated) story of KOI-5: A promising early Kepler planetary detection that was abandoned because … it was complicated.

5-day orbit

30-year orbit

400-year orbit

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

KEPLER OBJECT OF INTEREST (KOI) 5• Discovered in first 10 days of

Kepler data in 2009• Second Kepler candidate

(KOIs 1 – 3 previously known)

2021 January 11AAS 237 3

• Initially believed to be a Neptune-sized planet orbiting an older Sun-like star in a 5 day orbit

Kepler Light Curve and Transit For KOI 5Borucki et al. 2011Ciardi et al. 2021

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

THEN THINGS STARTED TO GO WRONG …

2021 January 11AAS 237 4

KOI-5 as seen by Kepler

Original Kepler Image

1 Full Moon (~60”)

MAST Archive

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

THEN THINGS STARTED TO GO WRONG …

2021 January 11AAS 237 5

KOI-5 as seen by Kepler

Original Kepler Image

1 Full Moon (~60”)

MAST Archive

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

THEN THINGS STARTED TO GO WRONG …KOI-5 discovered to have a stellar companion

2021 January 11AAS 237 6

KOI-5 as seen by Kepler

Original Kepler Image

1 Full Moon (~60”)

MAST Archive

Keck High-Resolution Image

1 Kepler Pixel (~4”)

Primary Star (A)

Companion Star

Kraus et al. 2014Furlan, Ciardi, et al. 2015Ciardi et al. 2021

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

THEN THINGS STARTED TO GO WRONG …KOI-5 discovered to have a stellar companion

2021 January 11AAS 237 7

KOI-5 as seen by Kepler

Original Kepler Image

1 Full Moon (~60”)

MAST Archive

Keck High-Resolution Image

1 Kepler Pixel (~4”)

Primary Star (A)

Companion Star

Kraus et al. 2014Furlan, Ciardi, et al. 2015Ciardi et al. 2021

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

THEN THINGS STARTED TO GO WRONG …And in fact … there are two companion stars

2021 January 11AAS 237 8

KOI-5 as seen by Kepler

Original Kepler Image

1 Full Moon (~60”)Keck High-Resolution Image

1 Kepler Pixel (~4”)

Primary Star (A)

Companion Star

MAST Archive

Secondary Star (B)

Tertiary Star (C)

Primary Star (A)

Gemini-North High-Resolution Image

Half 1 Kepler Pixel (~2”)

Kraus et al. 2014Furlan, Ciardi, et al. 2015Ciardi et al. 2021

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

THEN THINGS STARTED TO GO WRONG …

2021 January 11AAS 237 9

• Radial velocities didn’t match the transit orbit

• With the plethora (thousands!) of other Kepler candidates –left KOI-5 abandoned

Initial Radial velocities detected the orbit of the inner stellar companion around the primary star

Data from ExoFOPCiardi et al. 2021

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

AND ALONG CAME TESS: TOI 1241 = KOI 5 • TESS saw the same transit event 10 years later and it got me thinking

“Why didn’t we ever confirm KOI-5?”• Stellar companions were too far away from the primary star to be

responsible for the transits … there must be a 4th body in the system causing the transits

2021 January 11AAS 237 10

MAST Archive; Ciardi et al. 2021

TESS Light Curve and Transit For TOI 1241 = KOI 5

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

COMBINED THE RADIAL VELOCITIES AND IMAGING DATA TO SOLVE FOR THE SECONDARY STAR (B) ORBIT

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Stellar Mass A ~ 1.13 Solar MassesStellar Mass B ~ 1.09 Solar Masses Orbital Period ~ 29 years

STAR A

STAR B (2014)

STAR B (2020)

Radial Velocity Orbit Astrometric (imaging) Orbit

Ciardi et al. 2021 Ciardi et al. 2021

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

AFTER SUBTRACTION OF THE STELLAR ORBIT FOR STAR B, RADIAL VELOCITIES REVEAL THE PLANET

2021 January 11AAS 237 12

Planet Mass ≈ 57 Earth masses ; Planet Radius ≈ 7 Earth Radii

Ciardi et al. 2021

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

BUT THE ORBITS ARE NOT ALIGNED• Planet orbit is edge-on (transit) but the Stellar orbit is face-on• Stars and planet did not all form from the same circumstellar disk ?• Did the stellar companion push the planet into its current orbit ?

2021 January 11AAS 237 13

5-day orbit

30-year orbit

400-year orbit

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

KEPLER’S SECOND CANDIDATE KOI-5b is a Planet! • KOI 5 is a triple star system• Planet orbits the primary star

• 60% mass of Saturn • 75% radius of Saturn• 25% denser than Saturn

• Stellar orbit and planetary orbit are not in the same orbital plane

• The scientific detective work was made possible by the Kepler and TESS follow-up programs and the willingness of the community members to share publicly their observations, data, and thoughts

2021 January 11AAS 237 14

5-day orbit

30-year orbit

400-year orbit

“Injustice anywhere is a threat to justice everywhere.” – MLK, Letter from a Birmingham Jail

At Last! Confirmation of Kepler's Second Planetary CandidateExoplanets in Multi-Star SystemsKEPLER Object of Interest (KOI) 5Then things started to go Wrong …Then things started to go Wrong …Then things started to go Wrong …Then things started to go Wrong …Then things started to go Wrong …Then things Started to go Wrong …And Along Came TESS: TOI 1241 = KOI 5 Combined the Radial Velocities and Imaging data to Solve for the Secondary Star (B) OrbitAfter subtraction of the stellar Orbit for STAR B, �Radial Velocities Reveal the PlanetBut the ORBITS are NOT ALIGNEDKepler’s Second Candidate KOI-5b is a Planet! Slide Number 15