Laia Casamiquela

Chemical evolution of the Galactic disk using Open Clusters

ICC Winter MeetingFeb 2017

Chemical evolution of the Galactic disk using OCs

Laia Casamiquela

• Unravel the formation and evolution of the Milky Way (MW)

Detailed study of the MW components: bulge, thin disk, thick disk, halo

1. Galactic Archaeology

Chemical evolution of the Galactic disk using OCs

• Resolved stars provide a fossilrecord of the Galaxy evolution

• 6D parameter space: position + motion• Atmospheric parameters + chemistry• Ages

Wikimedia commons. Apod-NASA.

Laia Casamiquela

• Unravel the formation and evolution of the Milky Way (MW)

Detailed study of the MW components: bulge, thin disk, thick disk, halo

1. Galactic Archaeology

Chemical evolution of the Galactic disk using OCs

• Resolved stars provide a fossilrecord of the Galaxy evolution

• 6D parameter space: position + motion• Atmospheric parameters + chemistry• Ages

Gaia- Distance (25 µas @ V=15)- Tangential motion (0.23 km/s)- Radial velocity (13 km/s @ V=15; Resolution=11,000)

Gaia ESA webpageWikimedia commons. Apod-NASA.

Laia Casamiquela

• Unravel the formation and evolution of the Milky Way (MW)

Detailed study of the MW components: bulge, thin disk, thick disk, halo

1. Galactic Archaeology

Chemical evolution of the Galactic disk using OCs

Ground high-resolutionspectroscopic surveys:

- APOGEE R=22,500

- Gaia-ESO Survey R=45,000 (UVES)

- GALAH R=50,000

- WEAVE R=20,000

To enlarge the volume where Gaiadistances/motions are useful with:- Better radial velocities- Atmospheric parameters- ChemistryWikimedia commons. Apod-NASA.

• Resolved stars provide a fossilrecord of the Galaxy evolution

• 6D parameter space: position + motion• Atmospheric parameters + chemistry• Ages

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• Stars lock the chemical information of the interstellar gas from which wereformed

• Through stellar nucelosynthesis heavier elements are produced eventuallywill be deposited to the interstellar medium when star dies

2. Chemistry in the Galactic disk

Chemical evolution of the Galactic disk using OCs

Khan Academy

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• Stars lock the chemical information of the interstellar gas from which wereformed

• Through stellar nucelosynthesis heavier elements are produced eventuallywill be deposited to the interstellar medium when star dies

• Key: different types of stars, produce different ratios of elements at differenttimescales

2. Chemistry in the Galactic disk

Chemical evolution of the Galactic disk using OCs

North Arizona University

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• One possible observable: variation ofabundances through the Galactic disk

• Tracers must cover different positionsand ages:

• H II regions (Balser et al. 2011)• Cepheids (Lemasle et al. 2013, Genovalli et al.

2014,2015)• Planetary nebulae (Stanghellini & Haywood

2010)• Field giant stars (Huang et al. 2015, Anders et

al. 2016)• Open Clusters (OCs) (Carrera&Pancino 2011,

Frinchaboy et al. 2013)─ Main advantage: reliable distances and ages can be

derived from photometry

2. Chemistry in the Galactic disk

Chemical evolution of the Galactic disk using OCs

OCs: Carrera & Pancino (2011)

Cepheids: Genovali et al. (2014)

Tracers

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• Obtain vr and abundances for more than 35 chemical species in a sample of 25 Northern OCs (older than 0.3 Gyr, V<15)

• 18 OCs analyzed with 6-8 stars per OC• vr already analyzed in Casamiquela et al. (2016)

accuracies at the level of 0.1 km/s

3. The OCCASO survey

Chemical evolution of the Galactic disk using OCs

Laia Casamiquela

• Obtain vr and abundances for more than 35 chemical species in a sample of 25 Northern OCs (older than 0.3 Gyr, V<15)

• 18 OCs analyzed with 6-8 stars per OC• vr already analyzed in Casamiquela et al. (2016)

accuracies at the level of 0.1 km/s• Atmospheric parameters and [Fe/H] from stars derived

in Casamiquela et al. (2017, in prep)

3. The OCCASO survey

Chemical evolution of the Galactic disk using OCs

Laia Casamiquela

• Obtain vr and abundances for more than 35 chemical species in a sample of 25 Northern OCs (older than 0.3 Gyr, V<15)

• 18 OCs analyzed with 6-8 stars per OC• vr already analyzed in Casamiquela et al. (2016)

accuracies at the level of 0.1 km/s• Atmospheric parameters and [Fe/H] from stars derived

in Casamiquela et al. (2017, in prep)

3. The OCCASO survey

Chemical evolution of the Galactic disk using OCs

Laia Casamiquela

• Obtain vr and abundances for more than 35 chemical species in a sample of 25 Northern OCs (older than 0.3 Gyr, V<15)

• 18 OCs analyzed with 6-8 stars per OC• vr already analyzed in Casamiquela et al. (2016)

accuracies at the level of 0.1 km/s• Atmospheric parameters and [Fe/H] from stars derived

in Casamiquela et al. (2017, in prep)

3. The OCCASO survey

Chemical evolution of the Galactic disk using OCs

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• Example: [α/Fe]• SN type II produce α elements and few Fe-peak elements short timescale• SN type Ia produce mainly Fe-peak elements (Matteucci 2001) larger timescale

This implies a correlation with age: α-enhanced stars are expected to be old

4. Abundance ratios

Chemical evolution of the Galactic disk using OCs

Fuhrmann (2011)

Very local sampled<25 pcStars older than 10 Gyr identified as chemical thick disk

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• Example: [α/Fe]• SN type II produce α elements and few Fe-peak elements short timescale• SN type Ia produce mainly Fe-peak elements (Matteucci 2001) larger timescale

This implies a correlation with age: α-enhanced stars are expected to be oldLarger sample (APOGEE) thick disk has shorter scale length

4. Abundance ratios

Chemical evolution of the Galactic disk using OCs

Fuhrmann (2011)

Stars older tan 10 Gyridentified as chemicalthick disk

Hayden et al. (2015)

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5. NGC 6705/M 11 young α-enhanced OC

• Rich OC, young (0.3 Gyr), inner (RGC=6.5 kpc), thin disk (z=-90pc)• Using OCCASO data of 7 member stars we find:

Chemical evolution of the Galactic disk using OCs

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5. NGC 6705/M 11 young α-enhanced OC

• Rich OC, young (0.3 Gyr), inner (RGC=6.5 kpc), thin disk (z=-90pc)• Using OCCASO data of 7 member stars we find:

i. It is metal rich [Fe/H]=0.17±0.04 and homogeneous

Chemical evolution of the Galactic disk using OCs

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5. NGC 6705/M 11 young α-enhanced OC

• Rich OC, young (0.3 Gyr), inner (RGC=6.5 kpc), thin disk (z=-90pc)• Using OCCASO data of 7 member stars we find:

i. It is metal rich [Fe/H]=0.17±0.04 and homogeneousii. From the 5 α-elements analysed (Ca, Si, Ti, Mg, O) 3 show

clear enhancement

Chemical evolution of the Galactic disk using OCs

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5. NGC 6705/M 11 young α-enhanced OC

• α-rich stars in the Galactic thin disk?• This is not explained by chemical evolution models of the MW disk• Found similar cases in other samples: Bensby et al. (2014), Bergemann et al.

(2014), Chiappini et al. (2015)

Chemical evolution of the Galactic disk using OCs

Chiappini et al. (2015)

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5. NGC 6705/M 11 young α-enhanced OC

• α-rich stars in the Galactic thin disk?• This is not explained by chemical evolution models of the MW disk• Found similar cases in other samples: Bensby et al. (2014), Bergemann et al.

(2014), Chiappini et al. (2015)• M11 can be the metal rich tail of the previous outliers• What is their origin?

Chemical evolution of the Galactic disk using OCs

Casamiquela et al. (2017, in prep)

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OCCASO: People involved

Laia CasamiquelaCarme JordiLola Balaguer-Núñez

Ricardo CarreraCarme GallartCarlos Allende-PrietoAntonio Aparicio

Sergi Blanco-Cuaresma

Elena Pancino

Christina ChiappiniFriedrich Anders

Ulrike Heiter

Chemical evolution of the Galactic disk using OCs