Abstract
The existence of star-to-star light-element abundance variations in massive Galactic and extragalactic star clusters has fairly recently superseded the traditional paradigm of individual clusters hosting stars with the same age, and uniform chemical composition. Several scenarios have been put forward to explain the origin of this multiple stellar population phenomenon, but so far all have failed to reproduce the whole range of key observations. Complementary to high-resolution spectroscopy, which has first revealed and characterized chemically the presence of multiple populations in Galactic globular clusters, photometry has been instrumental in investigating this phenomenon in much larger samples of stars—adding a number of crucial observational constraints and correlations with global cluster properties—and in the discovery and characterization of multiple populations also in Magellanic Clouds’ intermediate-age clusters. The purpose of this review is to present the theoretical underpinning and application of the photometric techniques devised to identify and study multiple populations in resolved star clusters. These methods have played and continue to play a crucial role in advancing our knowledge of the cluster multiple population phenomenon, and promise to extend the scope of these investigations to resolved clusters even beyond the Local Group, with the launch of the James Webb Space Telescope.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Notes
Interestingly, it has been found that within these ‘peculiar’ clusters C–N, O–Na anticorrelations are present among stars with the same Fe abundance (see, e.g.Marino et al. 2011).
In the interiors of low-mass models, \({\log {R}}\) reaches values on the order of \(\sim 0.5\) only during the RGB advanced evolutionary phases. However in this regime the electron conduction opacity is the dominant contributor to the opacity in the He-core.
In case of complete ionisation, the mean molecular weight is given by \(\mu =\frac{1}{2X+\frac{3}{4}Y+\frac{Z}{2}}\).
We recall that, as long as the CNO sum (and initial Y) is the same, P1 and P2 theoretical isochrones are identical.
Lee (2017) has introduced the \(\mathrm{cn}_\mathrm{JWL}\) index, defined as \(\mathrm{cn}_\mathrm{JWL}=JWL39-\mathrm{Ca}_\mathrm{new}\), where JWL39 and \(\mathrm{Ca}_\mathrm{new}\) are two filters in the wavelength range between 3800 and 4050 Å. The \(\mathrm{cn}_{JWL}\) index is sensitive to the absorption of the CN band at 3883 Å, and the V-\(cn_{JWL}\) diagram is very similar to the V-\(c_y\) counterpart, but with a better MP resolving power.
The \(\delta _4\)index is also almost insensitive to reddening, given that \(E(\delta _4) \sim 0.01 E(B-V)\).
See also Milone et al. (2015) for a first discussion of this map for the Galactic GC NGC 2808, and alternative versions of chromosome maps. Zennaro et al. (2019) has very recently used another version of chromosome maps to study the Galactic GC NGC 2419, employing the pseudocolour \(C_{\mathrm{F275W}, \mathrm{F343N}, \mathrm{F438W}}=(\mathrm{F275W}-\mathrm{F343N})-(\mathrm{F343N}-\mathrm{F438W})\) and the colour \((\mathrm{F438W}-\mathrm{F814W})\). The construction and general properties of this map are the same as for Milone et al. (2017b) maps. For the same cluster, Larsen et al. (2019) have devised an analogous type of chromosome map, but based on the (F438W–F814W) and (F336W–F343N) pair of colours.
References
Bastian N, Lardo C (2018) Multiple stellar populations in globular clusters. Annu Rev Astron Astrophys 56:83–136. https://doi.org/10.1146/annurev-astro-081817-051839. arxiv:1712.01286
Bastian N, Lamers HJGLM, de Mink SE, Longmore SN, Goodwin SP, Gieles M (2013) Early disc accretion as the origin of abundance anomalies in globular clusters. Mon Not R Astron Soc 436(3):2398–2411. https://doi.org/10.1093/mnras/stt1745. arxiv:1309.3566
Bedin LR, Piotto G, Anderson J, Cassisi S, King IR, Momany Y, Carraro G (2004) \({\omega }\) Centauri: the population puzzle goes deeper. Astrophys J Lett 605(2):L125–L128. https://doi.org/10.1086/420847. arxiv:astro-ph/0403112
Bellini A, Renzini A, Anderson J, Bedin LR, Piotto G, Soto M, Brown TM, Milone AP, Sohn ST, Sweigart AV (2015) UV Insights into the complex populations of M87 globular clusters. Astrophys J 805(2):178. https://doi.org/10.1088/0004-637X/805/2/178. arxiv:1504.01742
Böhm-Vitense E (1958) Über die Wasserstoffkonvektionszone in Sternen verschiedener Effektivtemperaturen und Leuchtkräfte. Z Astrophys 46:108
Bragaglia A, Carretta E, Gratton R, D’Orazi V, Cassisi S, Lucatello S (2010) Helium in first and second-generation stars in globular clusters from spectroscopy of red giants. Astron Astrophys 519:A60. https://doi.org/10.1051/0004-6361/201014702. arxiv:1005.2659
Brott I, Hauschildt PH (2005) A PHOENIX model atmosphere grid for Gaia. In: Turon C, O’Flaherty KS, Perryman MAC (eds) The three-dimensional universe with Gaia, ESA Special Publication, vol 576, p 565. arxiv:astro-ph/0503395
Busso G, Cassisi S, Piotto G, Castellani M, Romaniello M, Catelan M, Djorgovski SG, Recio Blanco A, Renzini A, Rich MR, Sweigart AV, Zoccali M (2007) The peculiar horizontal branch morphology of the Galactic globular clusters NGC 6388 and NGC 6441: new insights from UV observations. Astron Astrophys 474:105–119. https://doi.org/10.1051/0004-6361:20077806. arxiv:0708.1736
Cabrera-Ziri I, Lardo C, Mucciarelli A (2019) Constant light element abundances suggest that the extended P1 in NGC 2808 is not a consequence of CNO-cycle nucleosynthesis. Mon Not R Astron Soc 485(3):4128–4133. https://doi.org/10.1093/mnras/stz707. arxiv:1903.03621
Caloi V, D’Antona F (2005) Helium self-enrichment in globular clusters and the second parameter problem in M 3 and M 13. Astron Astrophys 435:987–993. https://doi.org/10.1051/0004-6361:20041773. arxiv:astro-ph/0502195
Caloi V, D’Antona F (2007) NGC 6441: another indication of very high helium content in globular cluster stars. Astron Astrophys 463:949–955. https://doi.org/10.1051/0004-6361:20066074. arxiv:astro-ph/0610406
Carretta E, Gratton RG, Lucatello S, Bragaglia A, Bonifacio P (2005) Abundances of C, N, O in slightly evolved stars in the globular clusters NGC 6397, NGC 6752 and 47 Tuc. Astron Astrophys 433:597–611. https://doi.org/10.1051/0004-6361:20041892. arxiv:astro-ph/0411241
Carretta E, Bragaglia A, Gratton R, Lucatello S (2009a) Na-O anticorrelation and HB. VIII. Proton-capture elements and metallicities in 17 globular clusters from UVES spectra. Astron Astrophys 505:139–155. https://doi.org/10.1051/0004-6361/200912097. arxiv:0909.2941
Carretta E, Bragaglia A, Gratton RG, Lucatello S, Catanzaro G, Leone F, Bellazzini M, Claudi R, D’Orazi V, Momany Y, Ortolani S, Pancino E, Piotto G, Recio-Blanco A, Sabbi E (2009b) Na-O anticorrelation and HB. VII. The chemical composition of first and second-generation stars in 15 globular clusters from GIRAFFE spectra. Astron Astrophys 505:117–138. https://doi.org/10.1051/0004-6361/200912096. arxiv:0909.2938
Carretta E, Bragaglia A, Gratton R, D’Orazi D’Orazi V, Lucatello S (2011) A Strömgren view of the multiple populations in globular clusters. Astron Astrophys 535:A121. https://doi.org/10.1051/0004-6361/201117180. arxiv:1109.3199
Casagrande L, VandenBerg DA (2014) Synthetic stellar photometry-I. General considerations and new transformations for broad-band systems. Mon Not R Astron Soc 444:392–419. https://doi.org/10.1093/mnras/stu1476. arxiv:1407.6095
Cassisi S, Salaris M, Bono G (2002) The shape of the red giant branch bump as a diagnostic of partial mixing processes in low-mass stars. Astrophys J 565(2):1231–1238. https://doi.org/10.1086/324695. arxiv:astro-ph/0110247
Cassisi S, Salaris M (2013) Old stellar populations: how to study the fossil record of galaxy formation. Wiley-VCH, Weinheim
Cassisi S, Salaris M (2014) The main sequences of NGC 2808: constraints on the early disc accretion scenario. Astron Astrophys 563:A10. https://doi.org/10.1051/0004-6361/201323185. arxiv:1312.6363
Cassisi S, Salaris M, Pietrinferni A, Piotto G, Milone AP, Bedin LR, Anderson J (2008) The double subgiant branch of NGC 1851: the role of the CNO abundance. Astrophys J Lett 672:L115–L118. https://doi.org/10.1086/527035. arxiv:0711.3823
Cassisi S, Mucciarelli A, Pietrinferni A, Salaris M, Ferguson J (2013) Photometric properties of stellar populations in Galactic globular clusters: the role of the Mg-Al anticorrelation. Astron Astrophys 554:A19. https://doi.org/10.1051/0004-6361/201321311. arxiv:1303.5222
Cassisi S, Salaris M, Pietrinferni A, Hyder D (2017) On the determination of the He abundance distribution in globular clusters from the width of the main sequence. Mon Not R Astron Soc 464(2):2341–2348. https://doi.org/10.1093/mnras/stw2579. arxiv:1610.01755
Chantereau W, Salaris M, Bastian N, Martocchia S (2019) Helium enrichment in intermediate-age Magellanic Clouds clusters: towards an ubiquity of multiple stellar populations? Mon Not R Astron Soc 484(4):5236–5244. https://doi.org/10.1093/mnras/stz378. arxiv:1902.01806
Charbonnel C, Lagarde N (2010) Thermohaline instability and rotation-induced mixing. I. Low- and intermediate-mass solar metallicity stars up to the end of the AGB. Astron Astrophys 522:A10. https://doi.org/10.1051/0004-6361/201014432. arxiv:1006.5359
Cohen JG (1978) Abundances in globular cluster red giants. I. M3 and M13. Astrophys J 223:487–508. https://doi.org/10.1086/156284
Dalessandro E, Salaris M, Ferraro FR, Cassisi S, Lanzoni B, Rood RT, Fusi Pecci F, Sabbi E (2011) The peculiar horizontal branch of NGC 2808. Mon Not R Astron Soc 410(1):694–704. https://doi.org/10.1111/j.1365-2966.2010.17479.x. arxiv:1008.4478
Dalessandro E, Salaris M, Ferraro FR, Mucciarelli A, Cassisi S (2013) The horizontal branch in the UV colour-magnitude diagrams-II. The case of M3, M13 and M79. Mon Not R Astron Soc 430(1):459–471. https://doi.org/10.1093/mnras/sts644. arxiv:1212.4419
Dalessandro E, Massari D, Bellazzini M, Miocchi P, Mucciarelli A, Salaris M, Cassisi S, Ferraro FR, Lanzoni B (2014) First evidence of fully spatially mixed first and second generations in globular clusters: the case of NGC 6362. Astrophys J Lett 791(1):L4. https://doi.org/10.1088/2041-8205/791/1/L4. arxiv:1407.0484
Dalessandro E, Lapenna E, Mucciarelli A, Origlia L, Ferraro FR, Lanzoni B (2016) Multiple Populations in the old and massive small magellanic cloud globular cluster NGC 121. Astrophys J 829(2):77. https://doi.org/10.3847/0004-637X/829/2/77. arxiv:1607.05736
Dalessandro E, Lardo C, Cadelano M, Saracino S, Bastian N, Mucciarelli A, Salaris M, Stetson P, Pancino E (2018) IC 4499 revised: spectro-photometric evidence of small light-element variations. Astron Astrophys 618:A131. https://doi.org/10.1051/0004-6361/201833650. arxiv:1807.07618
D’Antona F, Caloi V, Montalbán J, Ventura P, Gratton R (2002) Helium variation due to self-pollution among Globular Cluster stars. Consequences on the horizontal branch morphology. Astron Astrophys 395:69–75. https://doi.org/10.1051/0004-6361:20021220. arxiv:astro-ph/0209331
D’Antona F, Bellazzini M, Caloi V, Pecci FF, Galleti S, Rood RT (2005) A helium spread among the main-sequence stars in NGC 2808. Astrophys J 631(2):868–878. https://doi.org/10.1086/431968. arxiv:astro-ph/0505347
di Criscienzo M, Ventura P, D’Antona F, Milone A, Piotto G (2010) The helium spread in the globular cluster 47 Tuc. Mon Not R Astron Soc 408(2):999–1005. https://doi.org/10.1111/j.1365-2966.2010.17168.x. arxiv:1006.2024
Dotter A, Ferguson JW, Conroy C, Milone AP, Marino AF, Yong D (2015) Stellar models of multiple populations in globular clusters-I. The main sequence of NGC 6752. Mon Not R Astron Soc 446(2):1641–1656. https://doi.org/10.1093/mnras/stu2170. arxiv:1410.4570
Dupree AK, Avrett EH (2013) Direct evaluation of the helium abundances in omega centauri. Astrophys J Lett 773(2):L28. https://doi.org/10.1088/2041-8205/773/2/L28. arxiv:1307.5860
Ferguson JW, Alexander DR, Allard F, Barman T, Bodnarik JG, Hauschildt PH, Heffner-Wong A, Tamanai A (2005) Low-temperature opacities. Astrophys J 623(1):585–596. https://doi.org/10.1086/428642. arxiv:astro-ph/0502045
Forbes DA, Bastian N, Gieles M, Crain RA, Kruijssen JMD, Larsen SS, Ploeckinger S, Agertz O, Trenti M, Ferguson AMN, Pfeffer J, Gnedin OY (2018) Globular cluster formation and evolution in the context of cosmological galaxy assembly: open questions. Proc R Soc Lond Ser A 474:20170616. https://doi.org/10.1098/rspa.2017.0616. arxiv:1801.05818
Gilligan CK, Chaboyer B, Cummings JD, Mackey D, Cohen RE, Geisler D, Grocholski AJ, Parisi MC, Sarajedini A, Ventura P, Villanova S, Yang SC, Wagner-Kaiser R (2019) Exploring the nature and synchronicity of early cluster formation in the Large Magellanic Cloud-IV. Evidence for multiple populations in Hodge 11 and NGC 2210. Mon Not R Astron Soc 486(4):5581–5599. https://doi.org/10.1093/mnras/stz1174. arxiv:1904.01434
Girardi L, Castelli F, Bertelli G, Nasi E (2007) On the effect of helium enhancement on bolometric corrections and Teff-colour relations. Astron Astrophys 468(2):657–662. https://doi.org/10.1051/0004-6361:20077129. arxiv:astro-ph/0703094
Gratton R, Bragaglia A, Carretta E, D’Orazi V, Lucatello S, Sollima A (2019) What is a globular cluster? An observational perspective. Astron Astrophys Rev 27:8. https://doi.org/10.1007/s00159-019-0119-3. arxiv:1911.02835
Gratton RG, Sneden C, Carretta E, Bragaglia A (2000) Mixing along the red giant branch in metal-poor field stars. Astron Astrophys 354:169–187
Gratton RG, Carretta E, Bragaglia A (2012) Multiple populations in globular clusters. Lessons learned from the Milky Way globular clusters. Astron Astrophys Rev 20:50. https://doi.org/10.1007/s00159-012-0050-3. arxiv:1201.6526
Gratton RG, Lucatello S, Sollima A, Carretta E, Bragaglia A, Momany Y, D’Orazi V, Cassisi S, Pietrinferni A, Salaris M (2013) The Na-O anticorrelation in horizontal branch stars. III. 47 Tucanae and M 5. Astron Astrophys 549:A41. https://doi.org/10.1051/0004-6361/201219976. arxiv:1210.4069
Grundahl F, Briley M, Nissen PE, Feltzing S (2002) Abundances of RGB stars in NGC 6752. Astron Astrophys 385:L14–L17. https://doi.org/10.1051/0004-6361:20020264
Hollyhead K, Martocchia S, Lardo C, Bastian N, Kacharov N, Niederhofer F, Cabrera-Ziri I, Dalessandro E, Mucciarelli A, Salaris M, Usher C (2019) Spectroscopic detection of multiple populations in the 2 Gyr old cluster Hodge 6 in the LMC. Mon Not R Astron Soc 484:4718–4725. https://doi.org/10.1093/mnras/stz317. arxiv:1902.02297
Iglesias CA, Rogers FJ (1996) Updated opal opacities. Astrophys J 464:943. https://doi.org/10.1086/177381
Johnson CI, Pilachowski CA (2010) Chemical abundances for 855 giants in the globular cluster omega centauri (NGC 5139). Astrophys J 722:1373–1410. https://doi.org/10.1088/0004-637X/722/2/1373. arxiv:1008.2232
Kamann S, Giesers B, Bastian N, Brinchmann J, Dreizler S, Göttgens F, Husser TO, Latour M, Weilbacher PM, Wisotzki L (2020) The binary content of multiple populations in NGC 3201. Astron Astrophys 635:A65. https://doi.org/10.1051/0004-6361/201936843. arxiv:1912.01627
King IR, Bedin LR, Cassisi S, Milone AP, Bellini A, Piotto G, Anderson J, Pietrinferni A, Cordier D (2012) Hubble space telescope observations of an outer field in omega centauri: a definitive helium abundance. Astron J 144:5. https://doi.org/10.1088/0004-6256/144/1/5. arxiv:1205.3760
Krishna Swamy KS (1966) Profiles of strong lines in K-Dwarfs. Astrophys J 145:174. https://doi.org/10.1086/148752
Kruijssen JMD (2015) Globular clusters as the relics of regular star formation in ‘normal’ high-redshift galaxies. Mon Not R Astron Soc 454(2):1658–1686. https://doi.org/10.1093/mnras/stv2026. arxiv:1509.02163
Lagioia EP, Milone AP, Marino AF, Cassisi S, Aparicio AJ, Piotto G, Anderson J, Barbuy B, Bedin LR, Bellini A, Brown T, D’Antona F, Nardiello D, Ortolani S, Pietrinferni A, Renzini A, Salaris M, Sarajedini A, van der Marel R, Vesperini E (2018) The Hubble space telescope UV legacy survey of galactic globular clusters-XII. The RGB bumps of multiple stellar populations. Mon Not R Astron Soc 475(3):4088–4103. https://doi.org/10.1093/mnras/sty083. arxiv:1801.03395
Lagioia EP, Milone AP, Marino AF, Cordoni G, Tailo M (2019a) The role of cluster mass in the multiple populations of galactic and extragalactic globular clusters. Astron J 158(5):202. https://doi.org/10.3847/1538-3881/ab45f2. arxiv:1909.08439
Lagioia EP, Milone AP, Marino AF, Dotter A (2019b) Helium variation in four small magellanic cloud globular clusters. Astrophys J 871(2):140. https://doi.org/10.3847/1538-4357/aaf729
Lardo C, Salaris M, Bastian N, Mucciarelli A, Dalessandro E, Cabrera-Ziri I (2018) Chemical inhomogeneities amongst first population stars in globular clusters. Evidence for He variations. Astron Astrophys 616:A168. https://doi.org/10.1051/0004-6361/201832999. arxiv:1805.09599
Larsen SS, Brodie JP, Grundahl F, Strader J (2014) Nitrogen Abundances and multiple stellar populations in the globular clusters of the fornax dSph. Astrophys J 797:15. https://doi.org/10.1088/0004-637X/797/1/15. arxiv:1409.0541
Larsen SS, Baumgardt H, Bastian N, Hernandez S, Brodie J (2019) Hubble Space Telescope photometry of multiple stellar populations in the inner parts of NGC 2419. Astron Astrophys 624:A25. https://doi.org/10.1051/0004-6361/201834494. arxiv:1902.01416
Lattanzio JC, Siess L, Church RP, Angelou G, Stancliffe RJ, Doherty CL, Stephen T, Campbell SW (2015) On the numerical treatment and dependence of thermohaline mixing in red giants. Mon Not R Astron Soc 446(3):2673–2688. https://doi.org/10.1093/mnras/stu2238. arxiv:1410.6517
Lee JW (2017) Multiple stellar populations of globular clusters from homogeneous Ca-CN photometry. II. M5 (NGC 5904) and a new filter system. Astrophys J 844(1):77. https://doi.org/10.3847/1538-4357/aa7b8c. arxiv:1706.07969
Lee YW, Joo SJ, Han SI, Chung C, Ree CH, Sohn YJ, Kim YC, Yoon SJ, Yi SK, Demarque P (2005) Super-helium-rich populations and the origin of extreme horizontal-branch stars in globular clusters. Astrophys J Lett 621(1):L57–L60. https://doi.org/10.1086/428944. arxiv:astro-ph/0501500
Madau P, Dickinson M (2014) Cosmic star-formation history. Annu Rev Astron Astrophys 52:415–486. https://doi.org/10.1146/annurev-astro-081811-125615. arxiv:1403.0007
Magic Z, Weiss A, Asplund M (2015) The Stagger-grid: a grid of 3D stellar atmosphere models. III. The relation to mixing length convection theory. Astron Astrophys 573:A89. https://doi.org/10.1051/0004-6361/201423760. arxiv:1403.1062
Marino AF, Villanova S, Piotto G, Milone AP, Momany Y, Bedin LR, Medling AM (2008) Spectroscopic and photometric evidence of two stellar populations in the Galactic globular cluster NGC 6121 (M 4). Astron Astrophys 490:625–640. https://doi.org/10.1051/0004-6361:200810389. arxiv:0808.1414
Marino AF, Milone AP, Piotto G, Villanova S, Gratton R, D’Antona F, Anderson J, Bedin LR, Bellini A, Cassisi S, Geisler D, Renzini A, Zoccali M (2011) Sodium-oxygen anticorrelation and neutron-capture elements in omega centauri stellar populations. Astrophys J 731:64. https://doi.org/10.1088/0004-637X/731/1/64. arxiv:1102.1653
Marino AF, Milone AP, Piotto G, Cassisi S, D’Antona F, Anderson J, Aparicio A, Bedin LR, Renzini A, Villanova S (2012a) The C+N+O Abundance of \({\omega }\) Centauri giant stars: implications for the chemical-enrichment scenario and the relative ages of different stellar populations. Astrophys J 746(1):14. https://doi.org/10.1088/0004-637X/746/1/14. arxiv:1111.1891
Marino AF, Milone AP, Sneden C, Bergemann M, Kraft RP, Wallerstein G, Cassisi S, Aparicio A, Asplund M, Bedin RL, Hilker M, Lind K, Momany Y, Piotto G, Roederer IU, Stetson PB, Zoccali M (2012b) The double sub-giant branch of NGC 6656 (M 22): a chemical characterization. Astron Astrophys 541:A15. https://doi.org/10.1051/0004-6361/201118381. arxiv:1202.2825
Marino AF, Milone AP, Przybilla N, Bergemann M, Lind K, Asplund M, Cassisi S, Catelan M, Casagrande L, Valcarce AAR, Bedin LR, Cortés C, D’Antona F, Jerjen H, Piotto G, Schlesinger K, Zoccali M, Angeloni R (2014) Helium enhanced stars and multiple populations along the horizontal branch of NGC 2808: direct spectroscopic measurements. Mon Not R Astron Soc 437(2):1609–1627. https://doi.org/10.1093/mnras/stt1993. arxiv:1310.4527
Marino AF, Milone AP, Sills A, Yong D, Renzini A, Bedin LR, Cordoni G, D’Antona F, Jerjen H, Karakas A, Lagioia E, Piotto G, Tailo M (2019) Chemical abundances along the 1G sequence of the chromosome maps: the globular cluster NGC 3201. Astrophys J 887(1):91. https://doi.org/10.3847/1538-4357/ab53d9. arxiv:1910.02892
Martins F, Morin J, Charbonnel C, Lardo C, Chantereau W (2020) Impact of a companion and of chromospheric emission on the shape of chromosome maps for globular clusters. Astron Astrophys 635:A52. https://doi.org/10.1051/0004-6361/201937212. arxiv:2001.07581
Martocchia S, Bastian N, Usher C, Kozhurina-Platais V, Niederhofer F, Cabrera-Ziri I, Dalessandro E, Hollyhead K, Kacharov N, Lardo C, Larsen S, Mucciarelli A, Platais I, Salaris M, Cordero M, Geisler D, Hilker M, Li C, Mackey D (2017) The search for multiple populations in Magellanic Cloud Clusters-III. No evidence for multiple populations in the SMC cluster NGC 419. Mon Not R Astron Soc 468(3):3150–3158. https://doi.org/10.1093/mnras/stx660. arxiv:1703.04631
Martocchia S, Cabrera-Ziri I, Lardo C, Dalessandro E, Bastian N, Kozhurina-Platais V, Usher C, Niederhofer F, Cordero M, Geisler D, Hollyhead K, Kacharov N, Larsen S, Li C, Mackey D, Hilker M, Mucciarelli A, Platais I, Salaris M (2018a) Age as a major factor in the onset of multiple populations in stellar clusters. Mon Not R Astron Soc 473:2688–2700. https://doi.org/10.1093/mnras/stx2556. arxiv:1710.00831
Martocchia S, Niederhofer F, Dalessandro E, Bastian N, Kacharov N, Usher C, Cabrera-Ziri I, Lardo C, Cassisi S, Geisler D, Hilker M, Hollyhead K, Kozhurina-Platais V, Larsen S, Mackey D, Mucciarelli A, Platais I, Salaris M (2018b) The search for multiple populations in Magellanic Cloud clusters-IV. Coeval multiple stellar populations in the young star cluster NGC 1978. Mon Not R Astron Soc 477(4):4696–4705. https://doi.org/10.1093/mnras/sty916. arxiv:1804.04141
Martocchia S, Dalessandro E, Lardo C, Cabrera-Ziri I, Bastian N, Kozhurina-Platais V, Salaris M, Chantereau W, Geisler D, Hilker M, Kacharov N, Larsen S, Mucciarelli A, Niederhofer F, Platais I, Usher C (2019) The search for multiple populations in Magellanic Clouds clusters-V. Correlation between cluster age and abundance spreads. Mon Not R Astron Soc. https://doi.org/10.1093/mnras/stz1596. arxiv:1906.03273
Milone AP, Marino AF, Cassisi S, Piotto G, Bedin LR, Anderson J, Allard F, Aparicio A, Bellini A, Buonanno R, Monelli M, Pietrinferni A (2012a) The Infrared eye of the wide-field camera 3 on the hubble space telescope reveals multiple main sequences of very low mass stars in NGC 2808. Astrophys J 754:L34. https://doi.org/10.1088/2041-8205/754/2/L34. arxiv:1206.5529
Milone AP, Piotto G, Bedin LR, Cassisi S, Anderson J, Marino AF, Pietrinferni A, Aparicio A (2012b) Luminosity and mass functions of the three main sequences of the globular cluster NGC 2808. Astron Astrophys 537:A77. https://doi.org/10.1051/0004-6361/201116539. arxiv:1108.2391
Milone AP, Piotto G, Bedin LR, King IR, Anderson J, Marino AF, Bellini A, Gratton R, Renzini A, Stetson PB, Cassisi S, Aparicio A, Bragaglia A, Carretta E, D’Antona F, Di Criscienzo M, Lucatello S, Monelli M, Pietrinferni A (2012c) Multiple stellar populations in 47 Tucanae. Astrophys J 744:58. https://doi.org/10.1088/0004-637X/744/1/58. arxiv:1109.0900
Milone AP, Marino AF, Bedin LR, Piotto G, Cassisi S, Dieball A, Anderson J, Jerjen H, Asplund M, Bellini A, Brogaard K, Dotter A, Giersz M, Heggie DC, Knigge C, Rich RM, van den Berg M, Buonanno R (2014) The M 4 Core Project with HST-II. Multiple stellar populations at the bottom of the main sequence. Mon Not R Astron Soc 439(2):1588–1595. https://doi.org/10.1093/mnras/stu030. arxiv:1401.1091
Milone AP, Marino AF, Piotto G, Renzini A, Bedin LR, Anderson J, Cassisi S, D’Antona F, Bellini A, Jerjen H, Pietrinferni A, Ventura P (2015) The hubble space telescope UV legacy survey of galactic globular clusters. III. A quintuple stellar population in NGC 2808. Astrophys J 808(1):51. https://doi.org/10.1088/0004-637X/808/1/51. arxiv:1505.05934
Milone AP, Marino AF, Bedin LR, Anderson J, Apai D, Bellini A, Bergeron P, Burgasser AJ, Dotter A, Rees JM (2017a) The HST large programme on \({\omega }\) Centauri-I. Multiple stellar populations at the bottom of the main sequence probed in NIR-Optical. Mon Not R Astron Soc 469(1):800–812. https://doi.org/10.1093/mnras/stx836. arxiv:1704.00418
Milone AP, Piotto G, Renzini A, Marino AF, Bedin LR, Vesperini E, D’Antona F, Nardiello D, Anderson J, King IR, Yong D, Bellini A, Aparicio A, Barbuy B, Brown TM, Cassisi S, Ortolani S, Salaris M, Sarajedini A, van der Marel RP (2017b) The Hubble Space Telescope UV legacy survey of galactic globular clusters-IX. The Atlas of multiple stellar populations. Mon Not R Astron Soc 464:3636–3656. https://doi.org/10.1093/mnras/stw2531. arxiv:1610.00451
Milone AP, Marino AF, Renzini A, D’Antona F, Anderson J, Barbuy B, Bedin LR, Bellini A, Brown TM, Cassisi S, Cordoni G, Lagioia EP, Nardiello D, Ortolani S, Piotto G, Sarajedini A, Tailo M, van der Marel RP, Vesperini E (2018) The Hubble Space Telescope UV legacy survey of galactic globular clusters-XVI. The helium abundance of multiple populations. Mon Not R Astron Soc 481:5098–5122. https://doi.org/10.1093/mnras/sty2573. arxiv:1809.05006
Monelli M, Milone AP, Stetson PB, Marino AF, Cassisi S, del Pino Molina A, Salaris M, Aparicio A, Asplund M, Grundahl F, Piotto G, Weiss A, Carrera R, Cebrián M, Murabito S, Pietrinferni A, Sbordone L (2013) The SUMO project I. A survey of multiple populations in globular clusters. Mon Not R Astron Soc 431:2126–2149. https://doi.org/10.1093/mnras/stt273. arxiv:1303.5187
Mucciarelli A, Origlia L, Ferraro FR, Pancino E (2009) Looking outside the galaxy: the discovery of chemical anomalies in three old large magellanic cloud clusters. Astrophys J Lett 695(2):L134–L139. https://doi.org/10.1088/0004-637X/695/2/L134. arxiv:0902.4778
Mucciarelli A, Lovisi L, Lanzoni B, Ferraro FR (2014) The helium abundance in the metal-poor globular clusters M30 and NGC 6397. Astrophys J 786(1):14. https://doi.org/10.1088/0004-637X/786/1/14. arxiv:1403.0595
Mucciarelli A, Lapenna E, Massari D, Ferraro FR, Lanzoni B (2015) The origin of the spurious iron spread in the globular cluster NGC 3201. Astrophys J 801(1):69. https://doi.org/10.1088/0004-637X/801/1/69. arxiv:1501.01968
Mucciarelli A, Dalessandro E, Massari D, Bellazzini M, Ferraro FR, Lanzoni B, Lardo C, Salaris M, Cassisi S (2016) NGC 6362: the least massive globular cluster with chemically distinct multiple populations. Astrophys J 824(2):73. https://doi.org/10.3847/0004-637X/824/2/73. arxiv:1604.04151
Nardiello D, Piotto G, Milone AP, Marino AF, Bedin LR, Anderson J, Aparicio A, Bellini A, Cassisi S, D’Antona F, Hidalgo S, Ortolani S, Pietrinferni A, Renzini A, Salaris M, Marel RPvd, Vesperini E (2015) The Hubble Space Telescope UV legacy survey of galactic globular clusters-IV. Helium content and relative age of multiple stellar populations within NGC 6352. Mon Not R Astron Soc 451(1):312–322. https://doi.org/10.1093/mnras/stv971. arxiv:1504.07876
Nardiello D, Piotto G, Milone AP, Rich RM, Cassisi S, Bedin LR, Bellini A, Renzini A (2019) Hubble Space Telescope analysis of stellar populations within the globular cluster G1 (Mayall II) in M 31. Mon Not R Astron Soc 485:3076–3087. https://doi.org/10.1093/mnras/stz629arxiv:1903.00488
Nataf DM, Gould A, Pinsonneault MH, Stetson PB (2011a) The Gradients in the 47 Tuc Red Giant Branch Bump and Horizontal Branch are consistent with a centrally concentrated. Helium-enriched second stellar generation. Astrophys J 736(2):94. https://doi.org/10.1088/0004-637X/736/2/94. arxiv:1102.3916
Nataf DM, Udalski A, Gould A, Pinsonneault MH (2011b) OGLE-III detection of the anomalous galactic bulge red giant branch bump: evidence of enhanced helium enrichment. Astrophys J 730:118. https://doi.org/10.1088/0004-637X/730/2/118. arxiv:1011.4293
Niederhofer F, Bastian N, Kozhurina-Platais V, Larsen S, Salaris M, Dalessandro E, Mucciarelli A, Cabrera-Ziri I, Cordero M, Geisler D, Hilker M, Hollyhead K, Kacharov N, Lardo C, Li C, Mackey D, Platais I (2017) The search for multiple populations in Magellanic Cloud clusters-I. Two stellar populations in the Small Magellanic Cloud globular cluster NGC 121. Mon Not R Astron Soc 464(1):94–103. https://doi.org/10.1093/mnras/stw2269. arxiv:1609.01595
Origlia L, Massari D, Rich RM, Mucciarelli A, Ferraro FR, Dalessandro E, Lanzoni B (2013) The Terzan 5 puzzle: Discovery of a third. Metal-poor component. Astrophys J Lett 779:L5. https://doi.org/10.1088/2041-8205/779/1/L5. arxiv:1311.1706
Pasquini L, Mauas P, Käufl HU, Cacciari C (2011) Measuring helium abundance difference in giants of NGC 2808. Astron Astrophys 531:A35. https://doi.org/10.1051/0004-6361/201116592. arxiv:1105.0346
Pietrinferni A, Cassisi S, Salaris M, Castelli F (2004) A large stellar evolution database for population synthesis studies. I. Scaled solar models and isochrones. Astrophys J 612(1):168–190. https://doi.org/10.1086/422498. arxiv:astro-ph/0405193
Pietrinferni A, Cassisi S, Salaris M, Castelli F (2006) A large stellar evolution database for population synthesis studies. II. Stellar models and isochrones for an \(\alpha \)-enhanced Metal Distribution. Astrophys J 642:797–812. https://doi.org/10.1086/501344. arxiv:astro-ph/0603721
Pietrinferni A, Cassisi S, Salaris M, Percival S, Ferguson JW (2009) A large stellar evolution database for population synthesis studies. V. Stellar models and isochrones with CNONa abundance anticorrelations. Astrophys J 697:275–282. https://doi.org/10.1088/0004-637X/697/1/275. arxiv:0903.0825
Piotto G, Villanova S, Bedin LR, Gratton R, Cassisi S, Momany Y, Recio-Blanco A, Lucatello S, Anderson J, King IR, Pietrinferni A, Carraro G (2005) Metallicities on the double main sequence of \(\omega \) Centauri imply large helium enhancement. Astrophys J 621:777–784. https://doi.org/10.1086/427796. arxiv:astro-ph/0412016
Piotto G, Bedin LR, Anderson J, King IR, Cassisi S, Milone AP, Villanova S, Pietrinferni A, Renzini A (2007) A triple main sequence in the globular cluster NGC 2808. Astrophys J Lett 661:L53–L56. https://doi.org/10.1086/518503. arxiv:astro-ph/0703767
Piotto G, Milone AP, Marino AF, Bedin LR, Anderson J, Jerjen H, Bellini A, Cassisi S (2013) Multi-wavelength Hubble Space telescope photometry of stellar populations in NGC 288. Astrophys J 775(1):15. https://doi.org/10.1088/0004-637X/775/1/15. arxiv:1306.5795
Piotto G, Milone AP, Bedin LR, Anderson J, King IR, Marino AF, Nardiello D, Aparicio A, Barbuy B, Bellini A, Brown TM, Cassisi S, Cool AM, Cunial A, Dalessandro E, D’Antona F, Ferraro FR, Hidalgo S, Lanzoni B, Monelli M, Ortolani S, Renzini A, Salaris M, Sarajedini A, van der Marel RP, Vesperini E, Zoccali M (2015) The Hubble Space Telescope UV legacy survey of galactic globular clusters. I. Overview of the project and detection of multiple stellar populations. Astron J 149(3):91. https://doi.org/10.1088/0004-6256/149/3/91. arxiv:1410.4564
Renzini A, D’Antona F, Cassisi S, King IR, Milone AP, Ventura P, Anderson J, Bedin LR, Bellini A, Brown TM, Piotto G, van der Marel RP, Barbuy B, Dalessandro E, Hidalgo S, Marino AF, Ortolani S, Salaris M, Sarajedini A (2015) The Hubble Space Telescope UV legacy survey of galactic globular clusters-V. Constraints on formation scenarios. Mon Not R Astron Soc 454:4197–4207. https://doi.org/10.1093/mnras/stv2268. arxiv:1510.01468
Salaris M, Cassisi S (2008) Stellar models with the ML2 theory of convection. Astron Astrophys 487:1075–1080. https://doi.org/10.1051/0004-6361:200810253. arxiv:0807.0863
Salaris M, Cassisi S (2014) Lithium and oxygen in globular cluster dwarfs and the early disc accretion scenario. Astron Astrophys 566:A109. https://doi.org/10.1051/0004-6361/201423722. arxiv:1404.6123
Salaris M, Weiss A (2002) Homogeneous age dating of 55 Galactic globular clusters. Clues to the galaxy formation mechanisms. Astron Astrophys 388:492–503. https://doi.org/10.1051/0004-6361:20020554. arxiv:astro-ph/0204410
Salaris M, Chieffi A, Straniero O (1993) The \({\alpha }\)-enhanced isochrones and their impact on the FITS to the galactic globular cluster system. Astrophys J 414:580. https://doi.org/10.1086/173105
Salaris M, Weiss A, Ferguson JW, Fusilier DJ (2006) On the primordial scenario for abundance variations within globular clusters: the Isochrone test. Astrophys J 645:1131–1137. https://doi.org/10.1086/504520. arxiv:astro-ph/0604137
Salaris M, Cassisi S, Pietrinferni A (2008) The Horizontal Branch of NGC 1851: constraints on the cluster subpopulations. Astrophys J Lett 678:L25–L28. https://doi.org/10.1086/588467. arxiv:0803.3546
Salaris M, Pietrinferni A, Piersimoni AM, Cassisi S (2015) Post first dredge-up [C/N] ratio as age indicator. Theoretical calibration. Astron Astrophys 583:A87. https://doi.org/10.1051/0004-6361/201526951. arxiv:1509.06904
Salaris M, Cassisi S, Pietrinferni A (2016) On the red giant branch mass loss in 47 Tucanae: constraints from the horizontal branch morphology. Astron Astrophys 590:A64. https://doi.org/10.1051/0004-6361/201628181. arxiv:1604.02874
Salaris M, Cassisi S, Schiavon RP, Pietrinferni A (2018) Effective temperatures of red giants in the APOKASC catalogue and the mixing length calibration in stellar models. Astron Astrophys 612:A68. https://doi.org/10.1051/0004-6361/201732340. arxiv:1801.09441
Salaris M, Cassisi S, Mucciarelli A, Nardiello D (2019) Detection of multiple stellar populations in extragalactic massive clusters with JWST. Astron Astrophys 629:A40. https://doi.org/10.1051/0004-6361/201936252. arxiv:1908.02229
Salaris M, Usher C, Martocchia S, Dalessandro E, Bastian N, Saracino S, Cassisi S, Cabrera-Ziri I, Lardo C (2020) Photometric characterization of multiple populations in star clusters: the impact of the first dredge-up. Mon Not R Astron Soc 492(3):3459–3464. https://doi.org/10.1093/mnras/staa089. arxiv:2001.04145
Saracino S, Bastian N, Kozhurina-Platais V, Cabrera-Ziri I, Dalessandro E, Kacharov N, Lardo C, Larsen SS, Mucciarelli A, Platais I, Salaris M (2019) An extragalactic chromosome map: the intermediate-age SMC cluster Lindsay 1. Mon Not R Astron Soc 489(1):L97–L101. https://doi.org/10.1093/mnrasl/slz135. arxiv:1909.02138
Saracino S, Martocchia S, Bastian N, Kozhurina-Platais V, Chantereau W, Salaris M, Cabrera-Ziri I, Dalessandro E, Kacharov N, Lardo C, Larsen SS, Platais I (2020) Chromosome maps of young LMC clusters: an additional case of coeval multiple populations. Mon Not R Astron Soc 493(4):6060–6070. https://doi.org/10.1093/mnras/staa644. arxiv:2003.01780
Sbordone L, Salaris M, Weiss A, Cassisi S (2011) Photometric signatures of multiple stellar populations in Galactic globular clusters. Astron Astrophys 534:A9. https://doi.org/10.1051/0004-6361/201116714. arxiv:1103.5863
Schiavon RP, Caldwell N, Conroy C, Graves GJ, Strader J, MacArthur LA, Courteau S, Harding P (2013) Star clusters in M31. V. Evidence for self-enrichment in Old M31 clusters from integrated spectroscopy. Astrophys J Lett 776(1):L7. https://doi.org/10.1088/2041-8205/776/1/L7. arxiv:1308.6590
Tailo M, D’Antona F, Milone AP, Bellini A, Ventura P, Di Criscienzo M, Cassisi S, Piotto G, Salaris M, Brown TM, Vesperini E, Bedin LR, Marino AF, Nardiello D, Anderson J (2017) The Hubble Space Telescope UV legacy survey of galactic globular clusters-XI. The horizontal branch in NGC 6388 and NGC 6441. Mon Not R Astron Soc 465(1):1046–1056. https://doi.org/10.1093/mnras/stw2790. arxiv:1610.08264
Thomas HC (1967) Sternentwicklung. VIII. Der Helium-Flash bei einem Stern von 1. 3 Sonnenmassen. Z Astrophys 67:420
Trampedach R, Stein RF, Christensen-Dalsgaard J, Nordlund Å, Asplund M (2014) Improvements to stellar structure models, based on a grid of 3D convection simulations-II. Calibrating the mixing-length formulation. Mon Not R Astron Soc 445(4):4366–4384. https://doi.org/10.1093/mnras/stu2084arxiv:1410.1559
VandenBerg DA, Edvardsson B, Eriksson K, Gustafsson B (2008) On the use of blanketed atmospheres as boundary conditions for stellar evolutionary models. Astrophys J 675:746–763. https://doi.org/10.1086/521600. arxiv:0708.1188
VandenBerg DA, Bergbusch PA, Dotter A, Ferguson JW, Michaud G, Richer J, Proffitt CR (2012) Models for metal-poor stars with enhanced abundances of C, N, O, Ne, Na, Mg, Si, S, Ca, and Ti, in Turn, at constant helium and iron abundances. Astrophys J 755:15. https://doi.org/10.1088/0004-637X/755/1/15. arxiv:1206.1820
Ventura P, Caloi V, D’Antona F, Ferguson J, Milone A, Piotto GP (2009) The C+N+O abundances and the splitting of the subgiant branch in the globular cluster NGC 1851. Mon Not R Astron Soc 399:934–943. https://doi.org/10.1111/j.1365-2966.2009.15335.x. arxiv:0907.1765
Villanova S, Geisler D, Piotto G (2010) Detailed abundances of red giants in the globular cluster NGC 1851: C+N+O and the origin of multiple populations. Astrophys J Lett 722:L18–L22. https://doi.org/10.1088/2041-8205/722/1/L18. arxiv:1008.4372
Villanova S, Geisler D, Piotto G, Gratton RG (2012) The helium content of globular clusters: NGC 6121 (M4). Astrophys J 748(1):62. https://doi.org/10.1088/0004-637X/748/1/62. arxiv:1201.3241
Worthey G, Hc Lee (2011) An empirical UBV RI JHK color-temperature calibration for stars. Astrophys J Suppl Ser 193:1. https://doi.org/10.1088/0067-0049/193/1/1. arxiv:astro-ph/0604590
Yong D, Grundahl F, Johnson JA, Asplund M (2008) Nitrogen abundances in giant stars of the globular cluster NGC 6752. Astrophys J 684:1159–1169. https://doi.org/10.1086/590658. arxiv:0806.0187
Yong D, Grundahl F, D’Antona F, Karakas AI, Lattanzio JC, Norris JE (2009) A large C+N+O abundance spread in giant stars of the globular cluster NGC 1851. Astrophys J Lett 695(1):L62–L66. https://doi.org/10.1088/0004-637X/695/1/L62. arxiv:0902.1773
Zennaro M, Milone AP, Marino AF, Cordoni G, Lagioia EP, Tailo M (2019) Four stellar populations and extreme helium variation in the massive outer-halo globular cluster NGC 2419. Mon Not R Astron Soc 487(3):3239–3251. https://doi.org/10.1093/mnras/stz1477. arxiv:1902.02178
Acknowledgements
We acknowledge the anonymous referee for his/her helpful suggestions. We warmly thank Adriano Pietrinferni for interesting discussions and the fruitful collaboration over all these years. We wish to acknowledge Giampaolo Piotto for his leading role in the development of photometric studies of MPs in globular clusters. Raffaele Gratton and Alvio Renzini are also warmly acknowledged for interesting discussions and collaborations on this research topic. We thank Nate Bastian and Carmela Lardo for several comments on an early draft of the manuscript. We are grateful to Carmela Lardo also for producing some of the figures. SC acknowledges support from Premiale INAF MITiC, from Istituto Nazionale di Fisica Nucleare (INFN) (Iniziativa specifica TAsP), progetto INAF Mainstream (PI: S. Cassisi), PLATO ASI-INAF agreement n.2015-019-R.1-2018, and grant AYA2013-42781P from the Ministry of Economy and Competitiveness of Spain.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Cassisi, S., Salaris, M. Multiple populations in massive star clusters under the magnifying glass of photometry: theory and tools. Astron Astrophys Rev 28, 5 (2020). https://doi.org/10.1007/s00159-020-00127-y
Received:
Published:
DOI: https://doi.org/10.1007/s00159-020-00127-y