M-Type Stars and Red Variables in the Galactic Center.

Nassau, J. J.; Blanco, V. M.

doi:10.1086/146514

Cited by 35 publications

(14 citation statements)

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“…In the same work, Baade also used for the first time the term stellar population of type II for the stars in the globular cluster NGC 6522 and its surrounding fields. The discovery of M giants by Nassau & Blanco (1958) first showed the presence of metal-rich old populations. Early historical work on the Galactic or Milky Way (MW) Bulge, hereafter the Bulge, is reviewed in Madore (2016).…”

Section: Introductionmentioning

confidence: 99%

Chemodynamical History of the Galactic Bulge

Barbuy

Chiappini

Gerhard

2018

Annu. Rev. Astron. Astrophys.

221

228

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The Galactic Bulge can uniquely be studied from large samples of individual stars, and is therefore of prime importance for understanding the stellar population structure of bulges in general. Here the observational evidence on the kinematics, chemical composition, and ages of Bulge stellar populations based on photometric and spectroscopic data is reviewed. The bulk of Bulge stars are old and span a metallicity range −1.5 < ∼ [Fe/H] < ∼ +0.5. Stellar populations and chemical properties suggest a star formation timescale below ∼2 Gyr. The overall Bulge is barred and follows cylindrical rotation, and the more metal-rich stars trace a Box/Peanut (B/P) structure. Dynamical models demonstrate the different spatial and orbital distributions of metal-rich and metalpoor stars. We discuss current Bulge formation scenarios based on dynamical, chemical, chemodynamical and cosmological models. Despite impressive progress we do not yet have a successful fully self-consistent chemodynamical Bulge model in the cosmological framework, and we will also need more extensive chrono-chemical-kinematic 3D map of stars to better constrain such models. arXiv:1805.01142v1 [astro-ph.GA] 3 May 2018 1 The bracket notation denotes logarithmic abundance ratios relative to Solar values, with [X/Y] = log(X/Y)star − log (X/Y)

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Section: Introductionmentioning

confidence: 99%

Chemodynamical History of the Galactic Bulge

Barbuy

Chiappini

Gerhard

2018

Annu. Rev. Astron. Astrophys.

221

228

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“…Early surveys of the bulge (Nassau & Blanco 1958) immediately revealed a distinguishing characteristic, namely, large numbers of M giants compared with the giant population in globular clusters and the halo. The breakthrough in achieving a physical understanding of the M giant population arose from the surveys undertaken by Victor and Betty Blanco using the newly commissioned grating/prism on the 4 m telescope at Cerro Tololo Inter-American Observatory (CTIO; Blanco et al 1984)-an effort that yielded thousands of photographic lowresolution classification spectra.…”

Section: Introductionmentioning

confidence: 99%

The Bulge Radial Velocity Assay (Brava). Ii. Complete Sample and Data Release

Kunder

Koch

Rich

et al. 2012

The Astronomical Journal

219

110

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We present new radial velocity measurements from the Bulge Radial Velocity Assay, a large-scale spectroscopic survey of M-type giants in the Galactic bulge/bar region. The sample of ∼4500 new radial velocities, mostly in the region −10 • < l < +10 • and b ≈ −6 • , more than doubles the existent published data set. Our new data extend our rotation curve and velocity dispersion profile to +20 • , which is ∼2.8 kpc from the Galactic center. The new data confirm the cylindrical rotation observed at −6 • and −8 • and are an excellent fit to the Shen et al. N-body bar model. We measure the strength of the TiOε molecular band as a first step toward a metallicity ranking of the stellar sample, from which we confirm the presence of a vertical abundance gradient. Our survey finds no strong evidence of previously unknown kinematic streams. We also publish our complete catalog of radial velocities, photometry, TiO band strengths, and spectra, which is available at the Infrared Science Archive as well as at UCLA.

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“…Until recently, it seemed that the basic metallicity scale was rmly established in Baade's Window, and that the majority of stars there had metallicities above solar, like that inferred for the nuclei of E and S0 galaxies. The high average metallicity was suggested by the profusion of late M giants; the complete absence of N-type carbon stars (Nassau & Blanco 1958;Blanco et al 1984;Blanco & Terndrup 1989), by the CMD morphology from broadband optical photometry (Terndrup 1988;Geisler & Friel 1992), by infrared photometry including measures of CO absorption (Frogel & Whitford 1987;Frogel et al 1990), and by medium resolution spectra of K and M giants (Whitford & Rich 1983;Rich 1988;Terndrup et al 1990Terndrup et al , 1991. While it is true that a satisfactory quantitative explanation is lacking for a number of the di erences between bulge giants and eld giants, particularly in near-IR colors, these di erences are in the expected sense for a population of stars with a mean metallicity equal to or greater than solar (Frogel 1993).…”

Section: Introductionmentioning

confidence: 99%

Implications of New JHK Photometry and a Deep Infrared Luminosity Function for the Galactic Bulge

Tiede¹,

Frogel²,

Terndrup³

1995

The Astronomical Journal

140

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We present deep near-IR photometry for Galactic bulge stars in Baade's Window, (l; b) = (1:0 ; 3:9 ); and another minor axis eld at (l; b) = (0 ; 6 ). We combine our data with previously published photometry and construct a luminosity function over the range 5:5 K 0 16:5, deeper than any previously published. The slope of this luminosity function and the magnitude of the tip of the rst ascent giant branch are consistent with theoretical values derived from isochrones with appropriate age and metallicity.We use the relationship between Fe/H] and the giant branch slope derived from near-IR observations of metal rich globular clusters by Kuchinski et al. AJ, 109, 1131AJ, 109, (1995] to calculate the mean metallicity for several bulge elds along the minor axis. For Baade's Window we derive h Fe=H]i = 0:28 0:16, consistent with the recent estimate of McWilliam & Rich ApJS, 91, 749 (1994)], but somewhat lower than previous estimates based on CO and TiO absorption bands and the JHK colors of M giants by Frogel et al. ApJ, 353, 494 (1990)]. Between b = 3 and 12 we nd a gradient in h Fe=H]i of 0:06 0:03 dex/degree or 0:43 0:21 dex/kpc for R 0 = 8 kpc, consistent with other independent derivations. We derive a helium abundance for Baade's Window with the R and R 0 methods and nd that Y = 0:27 0:03 implying Y= Z = 3:3 1:3. Next, we nd that the bolometric corrections for bulge K giants (V K 2) are in excellent agreement with empirical derivations based on observations of globular cluster and local eld stars. However, for the redder M giants we nd, as did Frogel & Whitford ApJ, 320, 199 (1987)], that the bolometric corrections di er by several tenths of a magnitude from those derived for eld giants and subsequently used in the Revised Yale Isochrones. This di erence { 3 { most likely arises from the stronger molecular blanketing in the V and I bands of the bulge giants relative to that in eld stars. From the luminosity function for Baade's Window and our bolometric corrections we calculate that (m M) 0 = 14:43 0:35 or R 0 = 7:7 1:2 kpc to the bulge based on the surface brightness uctuation method of Tonry & Schneider AJ, 96, 807 (1988)], with the distance to M31 and M32 used for calibration. { 4 {

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M-Type Stars and Red Variables in the Galactic Center.

Cited by 35 publications

References 0 publications

Chemodynamical History of the Galactic Bulge

Chemodynamical History of the Galactic Bulge

The Bulge Radial Velocity Assay (Brava). Ii. Complete Sample and Data Release

Implications of New JHK Photometry and a Deep Infrared Luminosity Function for the Galactic Bulge

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