Pristine Footprint 2015A

Pristine 15Awith CFHT/MegaCam

Belokurov et al. (2007)

PRISTINE: ESPADONS

This talk: Kim Venn (U.Victoria, Canada)

Pristine Team: co-leads Nicolas Martin & Else Starkenburg

Team Members: Rodrigo Ibata, Vanessa Hill, Pascale Jablonka, Piercarlo Bonifacio, Elisabetta Caffau, Patrick Francois, Ruben Sanchez-Janssen, Ray Carlberg, Julio Navarro, Alan McConnachie, Pat Cote, Steve Gwyn, Kris Youakim, Collin Keilty, and more.

Alan McConnachie, Pat Cote

Follow up spectra for V<14.7 with Espadons* Targeting metal-poor stars with [Fe/H] < -2, with initial analysis of red giants with T<6000 K.

38 Espadons targets observed in 2016A 21 with predicted [Fe/H] < -2.5 (>80% confidence)

Examination of key features: 13 showed weak & narrow CaT, MgB, & Balmer (62%)

SNR>20 pipeline spectra

No RV corr.s

No rebinning

850 855 860 865-3

-2

-1

0

1

Wavelength

P7

P27

P56

P45

P30

P6

P1

3 (of 13) new

metal-poor [Fe]< -2.5

bright stars

512 514 516 518 520-3

-2

-1

0

1

Wavelength

P7

P27

P56

P45

P30

P6

P1

3 (of 13) new

metal-poor [Fe]< -2.5

bright stars

SNR>20 pipeline spectra

No RV corr.s

No rebinning

8 (of 13) Espadons targets observed in 2016A

with predicted [Fe/H] < -2.5 with weak & narrow CaT, MgB, & Balmer coadded & smoothed for SNR > 30

5150 5160 5170 5180 5190-3

-2

-1

0

1

Wavelength

P27s

P43s

P7s

P56s

PP4

PP6s

P62s

P240s

8 (of 13) Espadons targets observed in 2016A

with predicted [Fe/H] < -2.5 with weak & narrow CaT, MgB, & Balmer coadded & smoothed for SNR > 65

Standard MOOG analysis preference for cooler stars - grid atmospheres, OSMARCS (Plez et al.) - shortened line list, (can squeeze out more) - LTE

example P7

8 (of 13) Espadons targets observed in 2016A

with predicted [Fe/H] < -2.5 with weak & narrow CaT, MgB, & Balmer coadded & smoothed for SNR > 65

Standard MOOG analysis preference for cooler stars - grid atmospheres, OSMARCS (Plez et al.) - shortened line list, (can squeeze out more) - LTE

Microturbulence? - few lines, small range can make determination difficult. - not clear if standard gravity- vturb relations apply. - can have significant effect on metallicities and ratios.

example PP6

8 (of 13) Espadons targets observed in 2016A

with predicted [Fe/H] < -2.5 with weak & narrow CaT, MgB, & Balmer coadded & smoothed for SNR > 65

Temperatures up to 400 K cooler than predicted from Pristine colour calibrations.

[Fe/H] tends to be similar, though Espadons ~lower and INT FERRE ~higher.

5000 5500 6000 6500

5000

5500

6000

6500

T(Pristine colours)

-3.5 -3 -2.5 -2

-3.5

-3

-2.5

-2

PRISTINE

SCULPTOR dSph: Jablonka et al. 2015, Hill et al. 2010, Tafelmeyer et al. 2010, Frebel et al. 2010, Letarte et al. 2010, Shetrone et al. 2003

CARINA dSph: Venn et al. 2012, Lemasle et al. 2012, Koch et al. 2008 Shetrone et al. 2003

UFD: Ishigaki et al. 2014, Frebel et al. 2014, 2010 Simon et al. 2014, Aden et al. 2011, Norris et al. 2010, Koch et al. 2010,

MWG: Aoki et al. 2013, Yong et al. 2013, Reddy et al. 2010, 2008, Frebel et al. 2010, Venn et al. 2004

Nes

s et

al.

2013

K

elle

r et a

l. 20

14

Some chemical evolution models support inhomogeneous mixing and thereby thatsome First Stars have high metallicities.

Wise et al. 2012

One goal of Pristine is to find more metal-poor stars, especially interesting metal-poor stars.

PRISTINE SCULPTOR dSph CARINA dSph UFD MWG

Limits Ba II 4554 1 mA 3 mA 10 mA

Low [Ba/Fe] in Segue I extremely interesting ... because high [Fe/H] from a single SN event in a low mass system, that did not produce much r-process.

Rare objects. First stars?

Frebel et al (2014)

Copious r-process enrichment from a single event in Ret II Ji et al. 2016 Nature

“Universal r-process pattern”, yet “incompatable with ordinary core collapse SN yields, but consistent with r-process production in neutron star mergers”.

Summary

1. Pristine-MegaCam survey with CaH&K filters appears to be excellent at finding metal-poor stars.

2. Pristine-Espadons has excellent spectral quality (resolution and SNR V<14.7) for follow-up studies.

3. ~60% of Pristine predicted [Fe/H] < -2.5 stars confirmed with spectroscopy (13/21 so far).

4. Analysis of 8/13 shows normal metal-poor halo stars, but these are bright objects that are idea for very detailed follow-up (e.g., r-process patterns).

PRISTINE objects are normal halo stars, none with low [Sr/Fe] often seen in dwarf galaxies, possibly due to metallicity-dependent nucleosynthetic yields.

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