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Home , George Van Biesbroeck, Stellar kinematics

Adriaan Blaauw, Stellar Populations and the Steven Majewski (University of Virginia) University of Chicago, Blaauw @ 1947-8, ‘52, ‘53-57 (photo: November 1947) University of Chicago, Yerkes Observatory Blaauw @ 1947-8, ‘52, ‘53-57 (photo: November 1947)

(back row, standing, from left) Daniel E. Harris, Guido Münch, Henry Chun, Su-Shu Huang, Douglas Duke, Mrs. Marshall H. Wrubel, Marshall H. Wrubel, Mr. Clearman, Arne Slettebak, William Bidelman, Roy Wickham, Irene Hansen, Frances H. Breen, Marjorie Hall Harrison, Gertrude Peterson, Robert H. Hardie, Arthur D. Code, K. N. Rao, Henry G. Horak, Marvin L. White, Frank N. Edmonds, Anne B. Underhill, Nancy G. Roman, Mr. Robinson, John Vosatka, Margaret Phillips, John G. Phillips, Mr. Sinha;

(front row) Thornton L. Page, William W. Morgan, Charles Ridell, Yu-Che Chang, , Luise Oettinger Herzberg, Gerard P. Kuiper, Jan H. Oort, George Van Biesbroeck, William A. Hiltner, , Gerhard Herzberg, Marguerite Van Biesbroeck, Fred Pearson, Subrahmanyan Chandrasekhar. McCormick Observatory, University of Virginia

• appointment with UVa Dept. of from 1967-1969+ • visited about twice a year for about a month at a time • advised UVa Ph.D. thesis (Katy Garmany :“A Spectroscopic Study of the OB Association III Cepheus “) • responsible for bringing in one new faculty member (Tolbert) Early Stellar Populations Work (distinct from young , calibrations)

• Blaauw (1939, BAN, VIII, 305; No. 315): “A determination of the longitude of the vertex and the ratio of the axes of the velocity-ellipsoid from the dispersions of the proper motions of faint stars measured at the Radcliffe Observatory”

• Blaauw (1944, BAN, X, 19; No. 363): “On systematic errors in the proper motions of the General Catalogue and on the preference to be given either to this catalogue or the Dritter Fundamentalkatalog”

• Hins & Blaauw* (1948, BAN, X, 365; No. 391): “-streaming among faint low-latitude stars investigated according to the dispersion method” (*A.B. completing work suggested by him to Dr. Hins but unfinished by Hins due to army service.) 1957 Vatican Conference

• In 1957, invited to the Pontifical Academy of Sciences’ Semaine d’Etude on the Problem of Stellar Populations

• “The Academy invites … illustrious scholars – comprising those who have especially studied a given question and have arrived at different conclusions -- to meet in Rome at its headquarters … so as to make a joint examination, free from all other preoccupations, of all data concerning the problem.”

• “…the number of participants is strictly limited, in order to ensure freer and more intimate discussions.” 1957 Vatican Conference

• In 1957, invited to the Pontifical Academy of Sciences’ Semaine d’Etude on the Problem of Stellar Populations

Baade's 1944 definition of two primary stellar populations based on CMD type.

Semaine d’Etude on the Problem of Stellar Populations of the Vatican Academy, May 1957 Semaine d’Etude on the Problem of Stellar Populations, May 1957 The 1957 Vatican Conference § A seminal event in the history of stellar populations studies. § Set modern context by defining principal Galactic populations. Blaauw at 1957 Vatican Conference § At age 42, Blaauw was among the younger participants (youngest of the “mid-career”). Blaauw at 1957 Vatican Conference

§ But as active a participant as other (more senior) participants.

Blaauw at 1957 Vatican Conference § Among the participants who gave multiple presentations:

• Session III: Young Population I Stars in the Spiral Arms of Our : – “Stellar Associations”

• Session VI: Stellar Populations in our Own Galaxy – “Kinematic Properties of the Strong and Weak-Line Stars” – A detailed analysis of “Miss Roman’s” data, focusing on planar kinematics Hins & Blaauw (1948, BAN, X, 365; No. 391): “Star-streaming among faint low-latitude stars investigated according to the dispersion method”

• “The galactic longitude of the vertex direction is found to be 323°.5 ± 1°.8 (m.e.). This confirms the coincidence with the direction of the found in an earlier application of the method, • and indicates that the vertex deviation exhibited by bright stars is but a local phenomenon.” Revising Galactic Coordinates Blaauw et al. (1960, MNRAS, 121, 123) Blaauw et al. (1959, ApJ, 130, 702) Revising Galactic Coordinates Blaauw (1960, MNRAS, 121, 164) Revising Galactic Coordinates Blaauw (1960, MNRAS, 121, 164)

Large variations by longitude due to local groupings like h and χ Persei.

Negative values due to solar height above . Revising Galactic Coordinates Blaauw (1960, MNRAS, 121, 164)

Farther objects more consistent, but still an overall tilt with respect to HI defined plane.

Stars and Stellar (1965) Chapter: “The Concept of Stellar Populations” • Began with recap of Baade’s work, stressing primary focus on physical properties, spectral class and with location. Stars and Stellar (1965) Chapter: “The Concept of Stellar Populations” • Began with recap of Baade’s work, stressing primary focus on physical properties, spectral class and luminosity with location. • Pointed out the subsequent emphasis on adding kinematical trends (building on work of Jeans, Lindlbad, Oort, etc. previously showing MW = superposed “star streams” of different densities).

Lindblad (1936) Stars and Stellar (1965) Chapter: “The Concept of Stellar Populations” • Began with recap of Baade’s work, stressing primary focus on physical properties, spectral class and luminosity with location. • Pointed out the subsequent emphasis on adding kinematical trends (building on work of Jeans, Lindlbad, Oort, etc. previously showing MW = superposed “star streams” of different densities

• But that investigation of differences in chemical composition was in infancy (indeed, chemical uniformity seemed most impressive in work to date).

Stars and Stellar (1965) Chapter: “The Concept of Stellar Populations” • Recalls Vatican Conference subdivision into additional, “intermediate” populations.

• See also Blaauw’s retrospective on the Vatican Conference published in IAU Symp. 164 (1995) and reprinted in (1999, A&SS 267, 45).

Stars and Stellar (1965) Chapter: “The Concept of Stellar Populations” • Recalls Vatican Conference subdivision into additional, “intermediate” populations. • Summarizes a top-down formation scenario resembling that described in Eggen, Lynden-Bell & Sandage (1962).

• Early-formed stars metal-poor from outer halo on radial, plunging orbits.

– Today have orbits to large radii and any orientation. – Metal poor, since formed before much of the ISM had cycled through generations of stars.

• Late formed stars are metal-rich stars of disk and on circular orbits.

– Formed from highly enriched gas after many generations of stars enriched ISM. Stars and Stellar (1965) Chapter: “The Concept of Stellar Populations” • Laments that 70% of mass is in “disk populations”, but their properties least well known, studies hampered by “prohibitively large interstellar absorption” and lack of high luminosity objects (like supergiants and Cepheids).

• “The most promising objects for determining the large scale density distribution are the red giants, through the spectral classification in the near infrared.”

Stars and Stellar (1965) Chapter: “The Concept of Stellar Populations” • Laments that 70% of mass is in “disk populations”, but their properties least well known, studies hampered by “prohibitively large interstellar absorption” and lack of high luminosity objects (like supergiants and Cepheids).

• “The most promising objects for determining the large scale density distribution are the red giants, through the spectral classification in the near infrared.”

• “These difficulties are also the reasons why the question of subdividing the disk population into categories with different degrees of central concen- tration formed a controversial subject at the Vatican Conference. We do not know how much larger the concentration toward the galactic center of the bright red giants is as compared to that of the weak-line stars.”

• Anticipating the eventuality of a comprehensive, near infrared spectroscopic study like that just now being undertaken as the APOGEE project.

The Concept of Galactic Chemical Enrichment Heavy elements created by nuclear fusion of lighter elements in stars.

Burbidge et al. 1957 (B2FH) Stars and Stellar (1965) Chapter: “The Concept of Stellar Populations” • Section 4: “Modern work on the relation between the kinematical and distributional properties and chemical parameters.”

• Summarizes new emphasis to incorporate chemistry: • Spectral classification of globular clusters (Morgan, Mayall, Kinman) • Nancy Roman: kinematics of weak versus strong line stars • Photometric/spectrophotometric means: UVX, Stromgren m, ΔS

ELS 1962

Wildey et al. 1962, Sandage 1969 Stars and Stellar (1965) Chapter: “The Concept of Stellar Populations” • “Of great significance for the study of stellar populations is Wallerstein’s U,V velocity diagram…with discrimination according to … [Fe/H].”

• “another significant way of discriminating stars with different kinematics… marking the stars…according to…the ratio of α-elements with respect to iron.”

Wallerstein 1962 Stars and Stellar (1965) Chapter: “The Concept of Stellar Populations” • “Of great significance for the study of stellar populations is Wallerstein’s U,V velocity diagram…with discrimination according to … [Fe/H].”

• “another significant way of discriminating stars with different kinematics… marking the stars…according to…the ratio of α-elements with respect to iron.”

• Vatican Conference supposed a monotonic chemical evolution with age. Desirable to introduce a “second dimension, by allowing stars to be simultaneously formed with different chemical abundances, possibly in different regions of the Galaxy.”

• “It must be anticipated that, in the course of … new developments, the subdivision of the galactic populations into types [as at Vatican Conference] will be gradually replaced by one using more exact chemical-abundance parameters…in combination with the data on and space distribution.” Late 1960s-1970s: McCormick Areas Programme “An interesting feature of the McCormick Areas Programme is the broad base of international collaboration.”

• Georgia: Dr. R.A. Bartaya of the Abastumani Observatory • Virginia: Dr. Charlie Tolbert, Dr. Phil Ianna and Katy Garmany • Tolbert brought to UVa to work on project for Blaauw.

Tolbert & Director Garmany Larry Fredrick Ianna Late 1960s-1970s: McCormick Areas Programme Blaauw, Tolbert, West, Bartaya (1976, A&AS, 23, 393): “Space distribution and kinematics of the Intermediate Population II stars. Part I: Photometry and Spectroscopy in Selected McCormick Fields”

Photometry, spectroscopy, proper motions in 57 of the McCormick Proper Motion Fields of van de Kamp & Vysstosky (1937) and Vyssotsky & Williams (1948):

• 1 mas/yr proper motions for 1800 stars over 50 yr baseline (Ianna, Garmany) at UVa • objective prism spectroscopy (Bartaya) at Abastumani Observatory • uvby β photometry (Tolbert, Garmany) from KPNO and ESO

Late 1960s-1970s: McCormick Areas Programme Blaauw & Garmany (1976, Tbilisi European Regional Meeting): “Space Distribution and Kinematics of F Stars” • : Vertical gradient mapped. Late 1960s-1970s: McCormick Areas Programme Blaauw & Garmany (1976, Tbilisi European Regional Meeting): “Space Distribution and Kinematics of F Stars”

• Proper Motions: U-V velocity distributions probed by metallicity:

1. For each distance group, velocity spread is always larger for the lower metal abundance group. 2. Velocity spread increases with distance from plane. U-V Velocity Distributions Blaauw (1970, IAU Symposium 38) Late 1960s-1970s: McCormick Areas Programme

• Unfortunately, after Blaauw become director of ESO, his visits slowed, NSF funding ran out, and the project languished.

• Garmany: “In these days, there was no discussion of what we now call the "two body" problem: I considered myself very lucky to claw my way back into astronomy after several years following my husband (to Atlanta, then to Denver, finally Boulder…). Maybe if I had a more secure position in those days, I would have been able to devote more energy to seeing that the Blaauw project data got published: I know it troubled me for many years - still does! There was certainly further effort on Blaauw's part: in the fall of 1974, Blaauw visited me in Denver to discuss the photometric data. I recall this very well because he stayed at our house for a few nights. I had a 9 month old son who thankfully was sleeping enough for us to sit at our kitchen table and talk about things - at that point I had no professional connections anywhere. But sadly we never got far enough for further publications on the motions of the stars.” SGP/SA141 + Meridional Plane Survey F and G stars, Basel RGU & Walraven VBLUW Photometry on 90cm Dutch telescope La Silla

Trefzger, Pel & Blaauw (1984, ESO Messenger, 35, 32)

From http://www.phoebe-project.org/2.0/docs/phoebe.atmospheres.html SGP/SA141 + Meridional Plane Survey F and G stars, Basel RGU & Walraven VBLUW Photometry on 90cm Dutch telescope La Silla

Trefzger, Pel & Blaauw (1984, ESO Messenger, 35, 32) Stars and Stellar Systems, vol. 5 Stars and Stellar Systems, vol. 5 SGP/SA141 + Meridional Plane Survey

Trefzger & Blaauw Trefzger, Pel & Blaauw (1984, ESO Mess., 35, 32) (1985, IAUS, 106, 151) Pel, Trefzger & Blaauw (1988, A&AS, 75, 29)

SGP/SA141 + Meridional Plane Survey

Trefzger & Blaauw Trefzger, Pel & Blaauw (1984, ESO Mess., 35, 32) (1985, IAUS, 106, 151) Pel, Trefzger & Blaauw (1988, A&AS, 75, 29)

Blaauw (1978, Astronomical papers dedicated to Bengt Stromgren): “Change in distribution with distance z demonstrates that at the distances mentioned we have entered the domain of intermediate population II.” Galactic Structure in Selected Areas The “Mt. Wilson Halo Mapping Project”: Mapping the density distributions of stars in the Galaxy.

Sandage 2001 Galactic Structure in SA57 (NGP)

z = 2.5 - 5 kpc

SRM (1992) SRM et al. (1994, 1996) Galactic Structure in Selected Areas • photometry • radial velocities • proper motions • spectroscopic abundances • Majewski (1992): Galactic structure and kinematics at the NGP (SA57) • Majewski et al. (1994): Kinematical substructure in the halo field (SA57) • Majewski et al. (1996): Large-scale streaming motions and halo substructure • Majewski & Siegel (2002): Faint velocities and density law • Dinescu et al. (2002): Detection of the Sagittarius stream in SA71 • Dinescu et al. (2006): Initial description of proper motions in 50 SAs • Casetti-Dinescu et al. (2008): and Sgr in SA71 • Casetti-Dinescu et al. (2009): in SA103 • Carlin et al. (2010): Anticenter Stream in SA76 • Carlin et al. (2012): Virgo Stellar Substructure in SA103 • Carlin et al. (2012): Sagittarius stream in six SAs

• deep CCD photometry

• Reid & Majewski (1993): Faint CCD Starcounts at the NGP (SA57) • Majewski (1999): Discovery of Sagittarius Stream in Selected Areas • Siegel et al. (2002): Density Laws from Photometric in SAs Galactic Structure in Selected Areas Carlin et al. (2012, ApJ, 744, 25):

“Kinematics and Chemistry of Stars along the Sagittarius Trailing Tidal Tail and Constraints on the Milky Way Mass Distribution”

Law et al. (2005), Law & SRM (2010) Galactic Structure in Selected Areas Carlin et al. (2012, ApJ, 744, 25):

“Kinematics and Chemistry of Stars along the Sagittarius Trailing Tidal Tail and Constraints on the Milky Way Mass Distribution”

Galactic Structure in Selected Areas Carlin et al. (2012, ApJ, 744, 25):

“Kinematics and Chemistry of Stars along the Sagittarius Trailing Tidal Tail and Constraints on the Milky Way Mass Distribution” Apache Point Observatory Galactic Evolution Experiment (APOGEE)

• 105 2MASS-selected giant stars across all Galactic populations. • 300 fiber, R ≥ 22,500, cryogenic spectrograph, 7 deg2 FOV

• H-band: 1.51-1.69µm AH /AV ~ 1/6 • S/N ≥ 140/res element @ H=12.2 for 3-hr total integration • RV uncertainty ≤100 m/s, 1-hr • 0.1 dex precision abundances for ~15 chemical elements (Fe, C, N, O, α, odd-Z, iron peak elements)

51 Stellar Atmospheric Parameters

Year 1 (Sep 2011-July 2012) Padua isochrone comparison for 48,000 stars in DR10. [Fe/H] log g log g

Teff Year 1+2 Disk Coverage (Hayden et al. 2014)

• Blaauw (1965): “The most promising objects for determining the large scale density distribution are the red giants, through the spectral classification in the near infrared.”

Year 1+2 Disk Coverage (Hayden et al. 2014) APOGEE Metallicities “Meridional Plane” APOGEE Metallicities

Trefzger, Pel & Blaauw Hayden et al. (2014) (1984, ESO Messenger, 35, 32) APOGEE-1 α-Abundances “Meridional Plane”

APOGEE-1 α-Abundances

SDSS-IV/ APOGEE-2: 2014-2020 Dual Hemisphere Observations Sky above 2 airmasses at each site

Apache Point Observatory

Las Campanas Observatory

• Carnegie Observatories collaboration, ≥ 75 nights per year. APOGEE-2 Target Plan Young Clusters in APOGEE-2 Iris x Hollandica Professor A. Blaauw

“This is from the range of Xiphium Irises (Spanish Iris) created in the Netherlands in 1891. They are popular with florists, but equally good in the garden. Professor Blaauw is the deepest of blues with its fall marked with yellow. You should normally see two buds swelling the stem before flowering - much more engaging than simply collecting them from a shop.”

From Mr. Johan van Scheepen (‪Taxonomist, Koninklijke Algemeene Vereniging voor Bloembollencultuur):

Named after Prof. Anton Hendrik Blaauw (1842-1942), professor of plant physiology at the University of Wageningen.

Tolbert: “As far as we can tell, he was unrelated to our Adriaan Blaauw. He was about the same age as our Blaauw's father, but does not appear to be one of his uncles. Whether there was a more distant connection, I was not able to learn…. Anton’s age is similar to that of Adriaan’s father and uncles, but these uncles lived north of Amsterdam whereas Anton lived in Wageningen.” Acknowledgements For background and remembrances: • Charlie Tolbert (UVa) • Katy Garmany (NOAO) • Larry Fredrick (UVa)

For research assistance: • Rachael Beaton (UVa) • Elizabeth Blanton-Kent (UVa Library)

For help with great iris bulb chase: • Brent and Becky Heath (Brett & Becky’s Bulbs, Gloucester, VA) • Mr. Johan van Scheepen (Taxonomist / Librarian Koninklijke Algemeene Vereniging voor Bloembollencultuur) • Charlie Tolbert

Dutch translation: Charlie Tolbert