Chemical evolution of the Galactic disk using Open Clusters

Transcription

1 Chemical evolution of the Galactic disk using Open Clusters ICC Winter Meeting Feb 2017

2 1. Galactic Archaeology Unravel the formation and evolution of the Milky Way (MW) Resolved stars provide a fossil record of the Galaxy evolution Detailed study of the MW components: bulge, thin disk, thick disk, halo 6D parameter space: position + motion Atmospheric parameters + chemistry Ages Wikimedia commons. Apod-NASA.

3 1. Galactic Archaeology Unravel the formation and evolution of the Milky Way (MW) Resolved stars provide a fossil record of the Galaxy evolution Detailed study of the MW components: bulge, thin disk, thick disk, halo 6D parameter space: position + motion Atmospheric parameters + chemistry Ages Gaia - Distance (25 V=15) - Tangential motion (0.23 km/s) - Radial velocity (13 V=15; Resolution=11,000) Wikimedia commons. Apod-NASA. Gaia ESA webpage

4 1. Galactic Archaeology Unravel the formation and evolution of the Milky Way (MW) Resolved stars provide a fossil record of the Galaxy evolution Detailed study of the MW components: bulge, thin disk, thick disk, halo 6D parameter space: position + motion Atmospheric parameters + chemistry Ages Ground high-resolution spectroscopic surveys: - APOGEE R=22,500 - Gaia-ESO Survey R=45,000 (UVES) - GALAH R=50,000 Wikimedia commons. Apod-NASA. - WEAVE R=20,000 To enlarge the volume where Gaia distances/motions are useful with: - Better radial velocities - Atmospheric parameters - Chemistry

5 2. Chemistry in the Galactic disk Stars lock the chemical information of the interstellar gas from which were formed Through stellar nucelosynthesis heavier elements are produced eventually will be deposited to the interstellar medium when star dies Khan Academy

6 2. Chemistry in the Galactic disk Stars lock the chemical information of the interstellar gas from which were formed Through stellar nucelosynthesis heavier elements are produced eventually will be deposited to the interstellar medium when star dies Key: different types of stars, produce different ratios of elements at different timescales North Arizona University

7 2. Chemistry in the Galactic disk Tracers One possible observable: variation of abundances through the Galactic disk Tracers must cover different positions and 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 OCs: Carrera & Pancino (2011) Cepheids: Genovali et al. (2014)

8 3. The OCCASO survey Obtain v r 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 v r already analyzed in Casamiquela et al. (2016) accuracies at the level of 0.1 km/s

9 3. The OCCASO survey Obtain v r 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 v r 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)

10 3. The OCCASO survey Obtain v r 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 v r 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)

11 3. The OCCASO survey Obtain v r 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 v r 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)

12 4. Abundance ratios 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 Very local sample d<25 pc Stars older than 10 Gyr identified as chemical thick disk Fuhrmann (2011)

13 4. Abundance ratios 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 Larger sample (APOGEE) thick disk has shorter scale length Stars older tan 10 Gyr identified as chemical thick disk Hayden et al. (2015) Fuhrmann (2011)

14 5. NGC 6705/M 11 young α-enhanced OC Rich OC, young (0.3 Gyr), inner (R GC =6.5 kpc), thin disk (z=-90pc) Using OCCASO data of 7 member stars we find:

15 5. NGC 6705/M 11 young α-enhanced OC Rich OC, young (0.3 Gyr), inner (R GC =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

16 5. NGC 6705/M 11 young α-enhanced OC Rich OC, young (0.3 Gyr), inner (R GC =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 ii. From the 5 α-elements analysed (Ca, Si, Ti, Mg, O) 3 show clear enhancement

17 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) Chiappini et al. (2015)

18 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? Casamiquela et al. (2017, in prep)

19 OCCASO: People involved Carme Jordi Lola Balaguer-Núñez Ricardo Carrera Carme Gallart Carlos Allende-Prieto Antonio Aparicio Sergi Blanco-Cuaresma Elena Pancino Christina Chiappini Friedrich Anders Ulrike Heiter