Stellar archaeology in the Milky Way Halo Variable stars and stellar populations in the new Milky Way satellites discovered by the SDSS Variable stars and stellar populations in the new Milky Way satellites discovered by the SDSS Ilaria Musella INAF – Osservatorio Astronomico di Capodimonte Napoli Clementini, Dall’Ora, Marconi, Ripepi, Greco, Di Fabrizio, Kinemuchi, Smith, Rodgers, Kuehn, Beers, Catelan, Pritzl

 -CDM hierarchical scenario ---> dSphs as Building Blocks of larger galaxies (such as the MW)  We should see remnants of this process  MW halo properties homogeneous with MW dSph satellites  -CDM hierarchical scenario ---> dSphs as Building Blocks of larger galaxies (such as the MW)  We should see remnants of this process  MW halo properties homogeneous with MW dSph satellites Galaxy formation mechanisms Galaxy formation mechanisms  Sgr dSph  CMa dSph/overdensity (debated)  Substructures in the M31 halo  Sgr dSph  CMa dSph/overdensity (debated)  Substructures in the M31 halo

Dwarf Spheroidal galaxies Old dSph’s Draco Ursa Minor Fornax Carina Sculptor LeoI LeoII Sextans Sagittarius Canis Major The impact of SDSS has been dramatic: 16 new objects have been discovered in the last years. The most numerous in the LG The most dark matter dominated Complex and unique SFH Metallicity (chemistry) Problem Variable Star Problem Missing Satellite Problem (MSP) new objects Bootes Bootes III Ursa Major Ursa Major II Canes Venatici I Canes Venatici II Coma Leo IV Leo T Hercules Bootes II Willman 1 Segue 1 Segue 2 Koposov I Koposov II new objects Bootes Bootes III Ursa Major Ursa Major II Canes Venatici I Canes Venatici II Coma Leo IV Leo T Hercules Bootes II Willman 1 Segue 1 Segue 2 Koposov I Koposov II

MW Inner 100 kpc

Milky Way satellites  Leo V  Boo II  Boo III

Old dSph’s GCs Dimensions --> Luminosity --> adapted from Belokurov et al BooII K1 K2 And XII And XIII And XI SDSS GCs And XV And XVI  BooIII   Segue 2 SDSS dSph’s new objects Bootes Bootes III Ursa Major Ursa Major II Canes Venatici I Canes Venatici II Coma Leo IV Leo T Hercules Bootes II Willman 1 Segue 1 Segue 2 Koposov I Koposov II new objects Bootes Bootes III Ursa Major Ursa Major II Canes Venatici I Canes Venatici II Coma Leo IV Leo T Hercules Bootes II Willman 1 Segue 1 Segue 2 Koposov I Koposov II GCs dSph’s luminosity and mass limit of galaxy formation? …. or tidally disrupted remnants?

 Fainter than previously known dSph’s:  V > 28 mag/arcsec -2 (M v ~ -7 mag, r h ≥ 100 pc)  Properties intermediate between GCs and dSph’s (M v ~ -7 mag, r h ≥ 100 pc)  Darkest known stellar systems (M/L from ~35 to ~1000)  Metal poor (…as metal poor as stars in the MW halo)  Irregular shape  distorted  tidally interacting ~ 13 gyr)  Host an ancient population (t ~ 13 gyr)  RR Lyrae  Satellite deficit reduced to a factor 4 (Simon & Geha, 2007) New faint dwarf satellites: “building blocks” of the MW halo?

Looking for the “building blocks” of the MW halo In the MW, most of the GCs with an RR population sharply divide into two distinct groups, based on (Oosterhoff 1939) Oo I = 0.55 d OoII = 0.65 d In the MW, most of the GCs with an RR population sharply divide into two distinct groups, based on (Oosterhoff 1939) Oo I = 0.55 d OoII = 0.65 d And outside the Milky Way? And the old dSphs? And outside the Milky Way? And the old dSphs? Oo I Gap Oo II Oo I Gap adapted from Catelan, Greco et al. 2009, in preparation

Our projects: Which is the Oostehoff type of SDSS faint dSphs? Published Bootes I Canes Venatici I Canes Venatici II Coma Accepted Leo IV Telescope time: 1.5m Loiano, 1.8m Lowell, 2.2m ESO, WIRO, INT, TNG,SOAR, WHT We use time-series photometry for the listed galaxy to study the properties of their variable stars In progress UMa II Hercules Bootes II To observe Bootes III

( α(J2000) 14:00:06 δ(J2000) 14:30:00 Ellipticity R h 13′.0 ± 0′.7 V tot (mag) 13.6 ± 0.5 mag [Fe/H] ± 0.07 mag (m-M) o 18.9 ± 0.2 mag revised ± 0.08 mag revised ± 0.08 mag D 60 kpc D 60 ± 6 kpc revised 66 ± 6 kpc revised 66 ± 6 kpc M V 0.5 mag M V -5.8 ± 0.5 mag μ V 28.3 ± 0.5 mag/arcsec -2 M/L … along with the UMi dSph one of the most dark matter dominated object in the Universe! Belokurov et al Dall’Ora et al. 2006, ApJL ( α(J2000) 14:00:06 δ(J2000) 14:30:00 Ellipticity R h 13′.0 ± 0′.7 V tot (mag) 13.6 ± 0.5 mag [Fe/H] ± 0.07 mag (m-M) o 18.9 ± 0.2 mag revised ± 0.08 mag revised ± 0.08 mag D 60 kpc D 60 ± 6 kpc revised 66 ± 6 kpc revised 66 ± 6 kpc M V 0.5 mag M V -5.8 ± 0.5 mag μ V 28.3 ± 0.5 mag/arcsec -2 M/L … along with the UMi dSph one of the most dark matter dominated object in the Universe! Belokurov et al Dall’Ora et al. 2006, ApJL Variable stars in the new SDSS dSph’s Bootes I Dall’Ora et al, 2006, ApJL Canes Venatici I Kuehn et al. 2007, ApJL Canes Venatici II Greco et al. 2008, ApJL Coma Musella et al. 2009, ApJL Leo IV Moretti et al., 2009, accepted, ApJL Hercules in progress Bootes II in progress Uma II in progress 11 RR Lyrae stars: 5 RRab’s, 5 RRc’s, 1 RRd, 1 LPV =0.69 d =0.37 d OoII

( α(J2000) 13:28:03 δ(J2000) 33:33:21.0 Ellipticity R h 8′.5 ± 0′.5 V tot (mag) 13.9 ± 0.5 mag [Fe/H] ± 0.02 mag (m-M) o ± 0.2 mag revised ± 0.06 mag revised ± 0.06 mag D 224 kpc D /-20 kpc revised /-5 kpc revised /-5 kpc M V 0.5 mag M V -7.9 ± 0.5 mag μ V 28.2 ± 0.5 mag/arcsec -2 M/L 221 ± 108 Zucker et al Kuehn et al. 2008, ApJL ( α(J2000) 13:28:03 δ(J2000) 33:33:21.0 Ellipticity R h 8′.5 ± 0′.5 V tot (mag) 13.9 ± 0.5 mag [Fe/H] ± 0.02 mag (m-M) o ± 0.2 mag revised ± 0.06 mag revised ± 0.06 mag D 224 kpc D /-20 kpc revised /-5 kpc revised /-5 kpc M V 0.5 mag M V -7.9 ± 0.5 mag μ V 28.2 ± 0.5 mag/arcsec -2 M/L 221 ± 108 Zucker et al Kuehn et al. 2008, ApJL Variable Stars RRab (in red) RRc (in blue) Candidate AC (in purple) Variables without periods (in cyan) Variable Stars RRab (in red) RRc (in blue) Candidate AC (in purple) Variables without periods (in cyan) 4 Age Components 13 Gyr (red line) 5 Gyr (blue line) 1.5 Gyr (green line) 0.6 Gyr (black line) 4 Age Components 13 Gyr (red line) 5 Gyr (blue line) 1.5 Gyr (green line) 0.6 Gyr (black line) [Fe/H] = -2.1/-2.0 (ZW84/CG97) [Fe/H] = -2.1/-2.0 (ZW84/CG97) Variable stars in the new SDSS dSph’s Bootes I Dall’Ora et al, 2006, ApJL Canes Venatici I Kuehn et al. 2007, ApJL Canes Venatici II Greco et al. 2008, ApJL Coma Musella et al. 2009, ApJL Leo IV Moretti et al., 2009, accepted, ApJL Hercules in progress Bootes II in progress Uma II in progress RRab’s RRc AC 23 RR Lyrae stars: 18 RRab’s, 5 RRc’s 3AC 58 candidate variable (RR Lyrae?) =0.60 d =0.38 d Oosterhoff intermediate

RRab RRc ( α(J2000) 12:57:10 δ(J2000) 34:19:15 Ellipticity 0.3 R h 3′.0 V tot (mag) 15.1 ± 0.5 mag [Fe/H] ± 0.12 mag (m-M) o ± 0.2 mag revised ± 0.06 mag revised ± 0.06 mag D 151 kpc D /-13 kpc revised /-5 kpc revised /-5 kpc M V 0.6 mag M V -4.8 ± 0.6 mag μ V 29.5 mag/arcsec -2 M/L 336 ± 240 Belokurov et al Greco et al. 2008, ApJL ( α(J2000) 12:57:10 δ(J2000) 34:19:15 Ellipticity 0.3 R h 3′.0 V tot (mag) 15.1 ± 0.5 mag [Fe/H] ± 0.12 mag (m-M) o ± 0.2 mag revised ± 0.06 mag revised ± 0.06 mag D 151 kpc D /-13 kpc revised /-5 kpc revised /-5 kpc M V 0.6 mag M V -4.8 ± 0.6 mag μ V 29.5 mag/arcsec -2 M/L 336 ± 240 Belokurov et al Greco et al. 2008, ApJL Variable stars in the new SDSS dSph’s Bootes I Dall’Ora et al, 2006, ApJL Canes Venatici I Kuehn et al. 2007, ApJL Canes Venatici II Greco et al. 2008, ApJL Coma Musella et al. 2009, ApJL Leo IV Moretti et al., 2009, accepted, ApJL Hercules in progress Bootes II in progress Uma II in progress __ M15 _ _ M3 __ M15 _ _ M3 2 RR Lyrae stars: 1 RRab, 1 RRc Several candidate BSSs =0.74 d =0.36 d OoII

( α(J2000) 12:26:59 δ(J2000) 23:54:15 Ellipticity 0.5 R h 5’ V tot (mag) 15.1 ± 0.5 mag [Fe/H] ± 0.07 mag (m-M) o 18.2 ± 0.2 mag revised ± 0.06 mag revised ± 0.06 mag D 44 kpc D 44 ± 4 kpc revised 40 ± 1 kpc revised 40 ± 1 kpc M V 0.6 mag M V -3.7 ± 0.6 mag μ V 29.0 mag/arcsec -2 M/L 448 ± 297 Belokurov et al Musella et al. 2009, ApJL ( α(J2000) 12:26:59 δ(J2000) 23:54:15 Ellipticity 0.5 R h 5’ V tot (mag) 15.1 ± 0.5 mag [Fe/H] ± 0.07 mag (m-M) o 18.2 ± 0.2 mag revised ± 0.06 mag revised ± 0.06 mag D 44 kpc D 44 ± 4 kpc revised 40 ± 1 kpc revised 40 ± 1 kpc M V 0.6 mag M V -3.7 ± 0.6 mag μ V 29.0 mag/arcsec -2 M/L 448 ± 297 Belokurov et al Musella et al. 2009, ApJL __ M68 _ _ M3 __ M68 _ _ M3 Variable stars in the new SDSS dSph’s Bootes I Dall’Ora et al, 2006, ApJL Canes Venatici I Kuehn et al. 2007, ApJL Canes Venatici II Greco et al. 2008, ApJL Coma Musella et al. 2009, ApJL Leo IV Moretti et al., 2009, accepted, ApJL Hercules in progress Bootes II in progress Uma II in progress 2 RR Lyrae stars: V1= RRab, V2= RRc, V3=short period variable =0.67 d =0.32 d OoII

3 RR Lyrae stars: 3 RRab’s 1 SX Phoenicis (V4) =0.66 d OoII __ M15 ( α(J2000) 11:32:57 δ(J2000) -00:32:00 Ellipticity 0.25 R h 3’.3 V tot (mag) 15.9 ± 0.5 mag [Fe/H] ± 0.10 mag (m-M) o 21.0 ± 0.2 mag revised ± 0.07 mag revised ± 0.07 mag D /-14 kpc revised 154 ± 5 kpc revised 154 ± 5 kpc M V 0.6 mag M V -5.1 ± 0.6 mag μ V 28.3 mag/arcsec -2 M/L 151 ± 177 Belokurov et al Moretti et al. 2009, ApJL, accepted ( α(J2000) 11:32:57 δ(J2000) -00:32:00 Ellipticity 0.25 R h 3’.3 V tot (mag) 15.9 ± 0.5 mag [Fe/H] ± 0.10 mag (m-M) o 21.0 ± 0.2 mag revised ± 0.07 mag revised ± 0.07 mag D /-14 kpc revised 154 ± 5 kpc revised 154 ± 5 kpc M V 0.6 mag M V -5.1 ± 0.6 mag μ V 28.3 mag/arcsec -2 M/L 151 ± 177 Belokurov et al Moretti et al. 2009, ApJL, accepted Variable stars in the new SDSS dSph’s Bootes I Dall’Ora et al, 2006, ApJL Canes Venatici I Kuehn et al. 2007, ApJL Canes Venatici II Greco et al. 2008, ApJL Coma Musella et al. 2009, ApJL Leo IV Moretti et al., 2009, accepted, ApJL Hercules in progress Bootes II in progress Uma II in progress A Pair with Leo V? (Koch et al. 2008)

( α(J2000) 16:31:02 δ(J2000) 12:47:30 Ellipticity 0.5 R h 8’.0 V tot (mag) 14.7 ± 0.5 mag [Fe/H] ± 0.07 mag (m-M) o 20.7 ± 0.2 mag D /-12 kpc M V 0.6 mag M V -6.0 ± 0.6 mag μ V 30.0 mag/arcsec -2 M/L 332 ± 221 Belokurov et al Work in progress ( α(J2000) 16:31:02 δ(J2000) 12:47:30 Ellipticity 0.5 R h 8’.0 V tot (mag) 14.7 ± 0.5 mag [Fe/H] ± 0.07 mag (m-M) o 20.7 ± 0.2 mag D /-12 kpc M V 0.6 mag M V -6.0 ± 0.6 mag μ V 30.0 mag/arcsec -2 M/L 332 ± 221 Belokurov et al Work in progress Variable stars in the new SDSS dSph’s Bootes I Dall’Ora et al, 2006, ApJL Canes Venatici I Kuehn et al. 2007, ApJL Canes Venatici II Greco et al. 2008, ApJL Coma Musella et al. 2009, ApJL Leo IV Moretti et al., 2009, accepted, ApJL Hercules in progress Bootes II in progress Uma II in progress

Variable stars in the new SDSS dSph’s Bootes I Dall’Ora et al, 2006, ApJL Canes Venatici I Kuehn et al. 2007, ApJL Canes Venatici II Greco et al. 2008, ApJL Coma Musella et al. 2009, ApJL Leo IV Moretti et al., 2009, accepted, ApJL Hercules in progress Bootes II in progress Uma II in progress ( α(J2000) 13:58:00 δ(J2000) 12:51:00 Ellipticity 0.21± 0.21 R h 4’.1 ± 1.6 V tot (mag) …. [Fe/H] -1.8 mag (m-M) o 18.1 ± 0.4 mag D 60 kpc D 60 ± 10 kpc revised 42 ± 8 kpc M V 1.1 mag M V -3.1 ± 1.1 mag revised -2.4 (-2.7) ± 0.7 (1.0) mag μ V 29.8 mag/arcsec -2 revised 28.4 mag/arcsec-2 ~ 35 M/L ~ 35 Wash et al. 2006, Wash et al (confirmed dSph), Wash et al. 2009, Kock et al (remnant in Sgr stream). Not clear nature Work in progress ( α(J2000) 13:58:00 δ(J2000) 12:51:00 Ellipticity 0.21± 0.21 R h 4’.1 ± 1.6 V tot (mag) …. [Fe/H] -1.8 mag (m-M) o 18.1 ± 0.4 mag D 60 kpc D 60 ± 10 kpc revised 42 ± 8 kpc M V 1.1 mag M V -3.1 ± 1.1 mag revised -2.4 (-2.7) ± 0.7 (1.0) mag μ V 29.8 mag/arcsec -2 revised 28.4 mag/arcsec-2 ~ 35 M/L ~ 35 Wash et al. 2006, Wash et al (confirmed dSph), Wash et al. 2009, Kock et al (remnant in Sgr stream). Not clear nature Work in progress

( α(J2000) 08:51:30 δ(J2000) 63:07:48 Ellipticity 0.5 R h 13’.6 V tot (mag) 14.3 ± 0.5 mag [Fe/H] ± 0.15 mag (m-M) o 17.5 ± 0.3 mag D 32 +5/-4 kpc M V 0.6 mag M V -3.8 ± 0.6 mag μ V 30.0 mag/arcsec -2 1 M/L 1722 ± 1226 Zucker et al Work in progress ( α(J2000) 08:51:30 δ(J2000) 63:07:48 Ellipticity 0.5 R h 13’.6 V tot (mag) 14.3 ± 0.5 mag [Fe/H] ± 0.15 mag (m-M) o 17.5 ± 0.3 mag D 32 +5/-4 kpc M V 0.6 mag M V -3.8 ± 0.6 mag μ V 30.0 mag/arcsec -2 1 M/L 1722 ± 1226 Zucker et al Work in progress Variable stars in the new SDSS dSph’s Bootes I Dall’Ora et al, 2006, ApJL Canes Venatici I Kuehn et al. 2007, ApJL Canes Venatici II Greco et al. 2008, ApJL Coma Musella et al. 2009, ApJL Leo IV Moretti et al., 2009, accepted, ApJL Hercules in progress Bootes II in progress Uma II in progress 1 Rrab =0.66 d OoII

Summary: The SDSS new dSph’s in the Oosterhoff plane Bootes Canes Venatici I Canes Venatici II Coma LeoIV UMa II Oo II Oo Intermediate Oo II 15 RR Lyrae stars 48 “ 2 “ 1 “

The SDSS new dSph’s in the Oosterhoff plane Oo II Gap Oo I

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