chasingoxygen ccas 2020jan23 slides...in the interiors of collapsing stars. we are made of star...

Chasing OxygenCCAS Presentation – 2020 Jan 23

Chasing Oxygen

Prof. Richard PoggeThe Ohio State UniversityDepartment of Astronomy

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Where does all this stuff come from?

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Graphic created by Prof. Jennifer Johnsonwww.astronomy.ohio-state.edu/~jaj/nucleo

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All the universe’s hydrogen and most of its helium was made during the first 15 minutes after the Big Bang

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Dying Low-Mass Stars

Red: Nitrogen

Green: Oxygen

Blue: HeliumNASA Hubble Space Telescope

Make N & C plussome O & He andtraces of heavyelements

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Exploding Massive Stars

NASA Hubble Space Telescope

Red: Oxygen

Green: Sulfur

Blue: hot electrons

Make O thru Ironup through Rb,some C & N

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Exploding White Dwarfs

NASA Chandra X-Ray Telescope

Make most ofthe Iron & Nickelgroup elements

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Merging Neutron Stars

LIGO artist’s impression

Make heaviest elements up to Uranium & Plutonium (?)

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“The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars.We are made of star stuff.”

Carl Sagan (Cosmos, 1980Episode 9: The Lives of the Stars)

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H

He

O

C

OthersH

73.9%

He24.7%

What is the Sun made of?

NASA

O - 0.63%C - 0.22%

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Si

Fe

O

Mg

S

Ni

Ca

Al

Others

O30.1%

Si15.1%

What is the Earth made of (in bulk)?

NASA “Blue Marble” West

Fe32.1%

Mg13.9%

SNiCa Al

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Al

Si

O

Fe

Ca

K

Na

Mg

Others

O46.6%

Si27.7%

What is Earth’s crust made of?

NASA “Blue Marble” West

Si27.7%

Al8.1%

FeCa

K Na Mg

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H

C

O

N

Ca

P

Others

O65%

C18.5%

H9.5%

What are we made of?

N

Ca

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Measuring cosmic oxygenis surprisingly difficult...

Expectation:Typically a few parts in 1000 to a few parts in 100,000

Hard to measure in stars:Solar value good to ~40%(!)Often have to use proxies

Needed: a tracer that works on cosmic scales…

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Young cluster of hotmassive stars

Surrounding gas isionized by UV lightfrom the hot stars

European Southern Observatory

HII Regions

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Spiral galaxies are filled with 100sof HII regions…

NASA Hubble Space Telescope17

Hydrogen

Helium

Oxygen

Neon

Iron

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HydrogenHelium

UV

Near

-IR

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OxygenNitrogen

Sulfur

Argon

Neon

UV

Near

-IR

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UV

Near-IR

Green Red

Red

Green

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CHemical Abundances Of Spirals(CHAOS)

Joint Ohio State – Univ of Minnesota projectfunded by the National Science Foundation

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The Multi-Object Double Spectrographs (MODS)on the Large Binocular Telescope

MODS1Installed August 2010

MODS2Installed April 2014

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MODS1 on the LBT(August 2010)

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Collimator MirrorsRedCamera

BlueCamera

RedGrating

BlueGrating

Red/Blue DichroicBeam Splitter

MODS Optics

Starlight

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LBT+MODS1 Spectrum of the Crab Nebula

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H SO

N

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Spiral Galaxy M101

NASA Hubble Space Telescope29

The M101 Campaign

Spring 2015 at the LBT

13 observations:7 multi-slit masks6 single-slit masks28 hours of observing

Yield:109 HII regions

Croxall et al. 2016, ApJ, 830, 4

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Oxygen-Rich

Oxygen-Poor

O/H

Rat

io

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Young-star Nitrogen

production dominates

Supernova Nitrogenproduction dominated

N/O

Rat

io

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A recent CHAOS finding:

The N/O distribution ingalaxies follows a nearlyuniversal pattern.

The starting N/O ratio is setby initial star formation:A strong start makes more Oahead of N, depressing N/O.

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What about Carbon?

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Leo PFaint dwarf galaxy ~15 Million light years away.

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Leo P is an extremely metal-deficient galaxy…

Skillman et al. 2013, AJ, 146, 3

UV Near

-IR

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M101

Leo P

Skillman et al. 2013, AJ, 146, 3

O/H

Rat

io

J0811+4730Izotov et al. 2017

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PIs: Prof. Evan Skillman (Minnesota) & Prof. Rick Pogge (OSU)Dr. Danielle Berg (OSU postdoc)Ness Mayker (OSU graduate student)Noah Rogers (Minnesota graduate student)Dr. Kevin Croxall (OSU & Expeed Software LLC)Prof. John Moustakas (Sienna College)

The CHAOS Team

US National Science FoundationCollaborative Grants AST-1108693 & AST-1715284

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chasingoxygen ccas 2020jan23 slides...in the interiors of collapsing stars. we are made of star...

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