OUTLINE OF THE TALK

Setting the scene

RR Lyrae as distance indicators

RR Lyrae as physics laboratory

RR Lyrae as stellar tracers

Conclusions

G. BONO, Univ. Rome Tor Vergata

Pulsation & Evolution of RR Lyrae stars

Photometry of HB stars in M3 (STERNHAUFEN [star cluster] by P. ten Bruggencate 1927) Direktor der Univ. Sternwarte in Gottingen, photographic plates by Shapley

The link between RR Lyrae & HB stars becomes clear after W. Baade and after Schwarzschild the difference between fundamental & overtones

RR Lyrae stars as distance indicators and stellar tracers

RR Lyrae variablesInitial mass (MS): ~0.8-0.9 Msun

Mass (HB): ~0.6-0.8 Msun

Core He + Shell H burning

[Fe/H] ~ -2.5 – 0.5 (Smith 2005)

Old: >10 Gyr (GCs, halo, bulge)Main Sequence (MS)

Horizontal Branch (HB)

Stetson + (2014)

M4

Simple stellar populations

RR Lyrae in Carina dSph

RRs

ACs

Coppola et al. (2015)

Complex Stellar Populations

ACs intermediate-age

RRs old-age

Horizonthal Branch stars

ZAHB

90% He-exh.

Central He burning [3α + 12C(α,γ)16O] – H-shell burning [CNO]

H+He partial ionization regions convective stable regions

Convective core + semi-convection!!!

RR Lyrae Pulsation & Evolutionary Properties

RR Lyrae Instability Strip

BHB

Easy selection either color-color plane (BHB) or variability (RRL)

Once upon a time RR Lyrae

S. I. Bailey (1854-1931)Pickering & Bailey (1895)

Bailey 1902 An. Har. 38, 1

J. C. Kapteyn (1851-1922)

Why stars pulsate?LO

G K

[cm

2/gr

]

LOG T

Radial Modes

K & Υ mechanisms Eddington docet!

The main culprit is Cp!

Why stars do not pulsate?Non-linear non-local time dependent

convective models …. + …. PdV

Stellingwerf RR Lyrae pulsation models

Based on the treatment of the transport equation by Castor (1968)Based on updates of Stellingwerf’s original code followed extensive and detailed investigations of RR Lyrae properties.

(Bono & Stellingwerf 1994 ApJS, Bono et al. 1997 A&AS, ApJ, Bon o et al. 2000, 2003 MNRAS, Marconi et al. 2003 ApJ, Di Criscienzo et al.2004 ApJ, Marconi & Clementini 2005, Marconi & Degl’Innocenti 2007, Marconi et al. 2009) + Budapest group

Non-linear convective models:U Comae field RRc variables

GB + (2000)Similar fits can also be provided for radial velocity, radius curves!!!

RRL as distance indicators

Mv = α + β [Fe/H]

Uncertainties on both α and β (theory & observations)Evolutionary effectsHeavy dependence on individual reddening uncertaintiesIndividual metal abundances

Bono et al. (2003), Cassisi et al. (2004), Catelan et al. (2005).

Basic leading physical arguments

Mbol = const + 5log R + 10log Teff Stefan-Boltzmann

P = √(R/g) von Ritter relationg=surface gravityP = Q ⁄ √ρ

Warning! The Period brings in the Stellar mass ….

Period-Luminosity-Color

Mbol = α + β*log P + γ*log TeffM_X = α + β*log P + γ* CI

Why we use PL instead of PLC relation? Observations: sensitivity to reddening uncertainties

Theory: sensitivity to color-temperature relations

Cepheid Pulsation & Evolutionary Properties Cepheid do obey to a PLC relations (consequence of a Mass-Luminosity relation)

LogL/Lo = α + β Log P + γ Log Te Mx = α + β Log P + γ CI The PL neglects the width in temperature of the IS This assumption is valid in the NIR, but not in the optical [σ (V)=0.2-0.3 mag]

Why RR Lyrae do not obey to a PL/PLC relation?

An open issue for more than half century!!!

RR Lyrae Distances Based on NIR PL relations

Longmore et al. (1989)

Log P [days]

mk

[mag

]

Why NIR is better than optical?

Bono et al. (2001)

Mv(RR) = α + β [Fe/H]

Affected by evolutionary effects!

MK

MV

MK

MV

Log PLog P

Why NIR is better than optical?

BC_I

BC_V

BC_K

Teff [K]

In the NIR the coolest are the brightest!!

Bono + & Marconi +

In the B-band the hottest are the brightest!!

RR Lyrae stars as distance indicators and stellar tracers

RR Lyrae variablesObserved NIR PLLongmore et al. (1989)

Theoretical PLZBono et al. (2001,2003)

Theoretical PLZCatelan et al. (2004)

Catelan et al. (2004)

PL/PLC in RR Lyrae & Cepheids

In Cepheids the PL/PLC is a direct consequence of the ML relation more massive stars are, at fixed Teff, brighter

lower gravities longer periods optical/NIR

The difference in mass for RR Lyrae stars is at most of the order of 20% the PL/PLC is the consequence of the variation in the BC

This is the reason why it shows up with R/I-band!!!

RR Lyrae in M5J, (71), K (120) with SOFI@NTTJ, (25), K (22) with NICS@TNG

33 RRab + 24 RRc

K

J-K

LOG P [d]

LOG P [d]

K

K

μ=14.44 ± 0.02 mag

Astrometric distance μ=14.44 ± 0.05 mag!!Rees (1993, 1996)

Coppola + (2011)

M4 a new spin on GC distance scale

M4 a new spin on GC distance scale

Selected optical/NIR light curves

Stetson et al. (2014))

M4 a new spin on GC distance scaleOptical/NIR PL relations

Braga et al. (2014))

NIR K-band PL relations

Wesenheit relationsW(BV) = V – Av/E(B-V) *(B-V) PROSReddening freeLinear over the entire period range <<Mimic a PLC relation>>Theory marginally dependent on mixing-length & on Y

CONSUncertainties in the reddening law (Cardelli like) Is the reddening law universal ?Accurate mean B,V,I or JHK magnitudes

M4 a new spin to GC distance scaleOptical/NIR PW relations

RR Lyrae stars as distance indicators and stellar tracersRR Lyrae variablesNIR/MIR PL relations

Dall'Ora et al. (2004), Madore et al. (2013)

XZ CygUV Oct

RR LyrSU Dra

Zero point from HST parallaxes (Benedict et al.

2011)

New accurate M4 distances Spitzer data (Neeley et al. 2015)

RR Lyrae stars as distance indicators and stellar tracers

M/Msun0.80 0.716 0.67 0.64 0.59 0.57 0.54

[Fe/H] -2.62 -2.14 -1.84 -1.62 -1.01 -0.70 -0.29

-enhanced mixture (BASTI, Marconi et al. 2015)

Pulsation models (calibration)

RR Lyrae stars as distance indicators and stellar tracers

M4 DM measure

DM(PLZ-

Glob)=11.296±0.003±0.026DM(PWZ-

Glob)=11.267±0.011±0.035

Braga et al. (2014)

Agreement with literature

Without optical bands...DM(PLZ-

Glob)=11.282±0.003±0.015DM(PWZ-Glob)=11.267±0.012±0.019

First Overtones vs Fundamentals

FO instability strip is narrower closer to a PL relation

The slope of FUs & FOs are different

The fundamentalization should be cautiously treated (Inno et al. 2013)

FOs on average fainter than FUs

Independent absolute calibration

Optical-NIR PW relations

Distance determinations based on optical-NIR PW relations reduced scatter Mild dependence on the reddening law

The slope instead of the fine structure

The coefficients of the color terms in the PW(V, K) relation is smaller than in the PW(J, H) and in the PW(H, KS) relations (0.13 vs 1.63 & 1.92 mag).

Reddening laws (Fritzpatrick et al. 2000)

Reddening laws (MW + Magellanic Clouds)

RRL as physics laboratory

Results of non-linear convective pulsation models for RR Lyrae stars

Complete topology of the instability strip for both F & FO modes.

Bono, Caputo & Marconi 1995 ApJLBono, Caputo, Castellani, Marconi 1997 A&AS

The pulsation relations by van Albada & Baker

On the basis of an extensive set of linear adiabatic pulsation models van Albada & Baker (1971, ApJ, 169, 311) derived the pulsation relations for RR Lyrae stars:

log P0 = -1.772 -0.68 log(M/Mo) + 0.84 log(L/Lo) + 3.48 log(6500/Te)

log(P0/P1) = 0.095 – 0.032 log (M/Mo) + 0.014 log(L/Lo) + 0.09 log(6500/Te)

Fundamental link between pulsation and evolutionary parameters

Link to theoretical Petersen’s diagram → pulsation mass estimates from double mode RR

Bono, Caputo, Castellani, Marconi 1996 ApJL

Petersen Diagram

P1/P

o

Po

Double mode RRL in Carina dSph

B

B

V

V

Phase Phase

Double-Mode Pulsators

Carina dSphCoppola et al. (2015)

Double-Mode Pulsators

Carina dSphCoppola et al. (2015)

ranking in mass & in metallicity

Solid observable!

Petersen Diagram

Soszynski + (2011,2015)

GCs as tracers of the Halo

Galaxy inventory:

Total mass 8x10^11Mo(Vera-Ciro + 2013)

Disk M~3x 10^10 Mo

Bulge M~1x 10^10 Mo(McMillan + 2011)

Halo M~1±0.4 x10^9 Mo(Deason + 2011)

Ngc(disk)/Ngc(halo)=20-30%

Total mass 10^7-10^8 MoA few percents

GCs as tracers of the HaloLeaman + (2013): 61 GGCs

Absolute & relative agesTwo AMRs for [Fe/H]≥-1.8

1/3 of the sample is, at fixed age, 0.6 dex more metal-rich

Eggen, Lynden-Bell Sandage (1962)Searle & Zinn (1978) \& {Sandage}(1962)

Their orbital properties are typical of disk/bulge GCs.

Leaman + (2013)

The bulk of the M.-R. sequence formed in the Galactic disk

A significant fraction of the M.-P. ones formed in dwarf galaxies that have been accreted by the MW.

GCs as tracers of the Halo

Marín-Franch + (2009))

M.-P. formed in situ The younger and M.-R. have been accreted

RR Lyrae (& BHB) as Halo tracers

New findings

Kinman et al. (2007, 2012)Anticenter: 51BHB + 58 RRNGP a few hundred

Galactic V motion is retrogradefor RR+BHB with R_G > 10 Kpc[Carollo+ 2010; Beers+ 2012]The Outer halo is retrogradewhen compared with the solar neighborhood/inner halo

According to Angular momentum Distributions stars in the halo can be split in two groups: Main concentration (relaxed, Hattori & Yoshii 2011) + outliers

The ratio between out. & main con.increases as a function of R_GThe halo becomes more spherical with increasing R_GSimulations (McCarthy + 2012) Predict inner halo more flattened than outer halo

Photometric surveys of the halo

QUEST Zinn + (2013)CATALINA Drake + (2013)LONEOS Miceli + (2008)ASAS Pojmanski + (2005)LINEAR Sesar + (2013)

Oosterhoff dicothomy & Bailey diagramOoI GCs have <Pf>~0.55 days OoII GCs <Pf>~0.65 days The same applies for first overtones

The fraction of RRc is smaller in OoI (~17\%) than in OoII (~44%)

OoI GCs cover a broad range in iron & more M.-R, than OoII GCs that are typically very M.-P. ([Fe/H]~-2 dex)

GC in the MCs are typically Oosterhoff intermediate

The same applies for (some) Dwarf galaxies in the Local GroupBono + (1997)

Ab

Av

Log P

A New Spin!

Fiorentino et al. (2014)

A New Spin!

Fiorentino et al. (2014)

and then …. Sculptor dSph536 RR Lyrae (82 new discoveries, 320 new pulsation analysis)

Martinez Vazquez + 2015 W(V,B-V) & W(V,B-I) Independent of metal content

and then …. Sculptor dSph536 RR Lyrae (82 new discoveries, 320 new pulsation analysis)

Martinez Vazquez + 2015 I-band PL relation dependent on metal content

GAIAGlobal Astrometric Interferometer for Astrophysics

Waiting for E-ELTMICADO – AO assisted– J~K~30-31 mag

Cepheids in Coma

Ho only based on Primary distance indicators!!!

Riess et al. 2011 -- SHOES

NGC 5584 SN Ia + Cepheids

8 (6) calibrating SN Ia

NIR phot. of external Cepheids

Homogeneous optical/NIR Phot. (WFC3)

NIR PL relations external galaxies Three independent zero-points:

NGC4258 (geometric/maser distance)

9 Gal. Ceph. Trigonometric parallaxes

92 LMC Cepheids

Estimate of Ho with a precision of ~3%W

mν

Neff

Ho

Ho=73.8 ± 2.4 km / (s Mpc)

w = −1.08 ± 0.10

Neff = 4.2 ± 0.7

mν~0.1 ev

Freedman & Madore (2010)

WMAP + PLANCK Ho = 67.8 ± 0.9 km / (s Mpc)

Tension or not tension?

Resolved sources 2.5σ level

Re-analysis by Efstathiou (2014) using a new maser distance to NGC4258 1.9σ See also Lensing + Megamaser + AGN

Tips for possible discussions

Blazho effect

Formation and propagation of sonic shocks

Formation of He lines in the optical regime

Period Changes Oosterhoff dichotomy

Conclusions

We desperately need multi-band photometry toidentify outer Halo RR Lyrae + red HB stars

RR Lyrae stars are solid distance indicators & Physics laboratories

RR Lyrae (Blue HB) are fundamental beacons to constrain the Galactic Halo & Bulge

CreditsTo young, differently young & senior

colleagues with whom I have the pleasure to share this wonderful adventure

THANKS!

A. Pietrinferni, M. Fabrizio, V. F. Braga, I. Ferraro, G. Iannicola, L. Inno, R. Da Silva G. CoppolaOAC, M. Marconi,

M. Dall’Ora, M. MonelliIAC + G. FiorentinoOAB , M. Nonino, M. Marengo, J. Neeley + ESO + CARNEGIE