The Thickening of the Thin Disk in the Third Galactic Quadrant

Carraro, G.; Vazquez, R. A.; Costa, E.; Ahumada, J. A.; Giorgi, E. E.

doi:10.1088/0004-6256/149/1/12

Cited by 25 publications

(29 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As for the grand design structures in the TGQ we are in the position to confirm the angular extension of the Local Arm from 220 • to 275 • . Our findings are in good agreement with previous studies (see Carraro et al 2015) we have already performed in the sense that our evidences indicate that the Galactic plane is not only warped but also flared. This is, thin disk population shows a pattern similar to the shown by the thick disk.…”

Section: Discussionsupporting

confidence: 94%

The nearby Galaxy structure toward the Vela Gum nebula

et al. 2015

View full text Add to dashboard Cite

We report on $UBVI$ photometry and spectroscopy for MK classification purposes carried out in the fields of five open clusters projected against the Vela Gum in the Third Galactic Quadrant of the Galaxy. They are Ruprecht 20, Ruprecht 47, Ruprecht 60, NGC 2660 and NGC 2910. We could improve/confirm the parameters of these objects derived before. The spectroscopic parallax method has been applied to several stars located in the fields of four out of the five clusters to get their distances and reddenings. With this method we found two blue stars in the field of NGC 2910 at distances that make them likely members of Vela OB1 too. Also, projected against the fields of Ruprecht 20 and Ruprecht 47 we have detected other young stars favoring not only the existence of Puppis OB1 and OB2 but conforming a young stellar group at $\sim1$ kpc from the Sun and extending for more than 6 kpc outward the Galaxy. If this is the case, there is a thickening of the thin Galactic disk of more than 300 pc at just 2-3 kpc from the Sun. Ruprecht 60 and NGC 2660 are too old objects that have no physical relation with the associations under discussion. An astonishing result has been the detection in the background of Ruprecht 47 of a young star at the impressive distance of 9.5 kpc from the Sun that could be a member of the innermost part of the Outer Arm. Another far young star in the field of NGC 2660, at near 6.0 kpc, may become a probable member of the Perseus Arm or of the inner part of the Local Arm. The distribution of young clusters and stars onto the Third Galactic Quadrant agrees with recent findings concerning the extension of the Local Arm as revealed by parallaxes of regions of star formation. We show evidences too that added to previous ones found by our group explain the thickening of the thin disk as a combination of flare and warp.Comment: Accepted for publication in New Astronom

show abstract

Section: Discussionsupporting

confidence: 94%

The nearby Galaxy structure toward the Vela Gum nebula

et al. 2015

View full text Add to dashboard Cite

show abstract

“…This model of thick disk formation predicts a negative radial age gradient in geometrically-defined thick disks, which was found to be indeed the case for the Milky Way using APOGEE data (Martig et al 2016). Flaring in Milky Way stellar populations of limited age range has been found by Kalberla et al (2014) Feast et al (2014) (Cepheids), Carraro et al (2015) (young clusters) and in LAMOST (Wan et al 2017;Wang et al 2018;Xiang et al 2018) and APOGEE (Mackereth et al 2017) mono-age populations. A proper Milky Way disk mass model is needed to asses the interplay among the flares of different mono-age populations on the overall scale-height variation with radius (that of the total disk mass).…”

Section: Variation Of Disk Thickness With Galactocentric Radiussupporting

confidence: 60%

Yule-Simpson’s paradox in Galactic Archaeology

Minchev

Matijevič

Guiglion

et al. 2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Simpson's paradox, or Yule-Simpson effect, arises when a trend appears in different subsets of data but disappears or reverses when these subsets are combined. We describe here seven cases of this phenomenon for chemo-kinematical relations believed to constrain the Milky Way disk formation and evolution. We show that interpreting trends in relations, such as the radial and vertical chemical abundance gradients, the age-metallicity relation, and the metallicity-rotational velocity relation (MVR), can lead to conflicting conclusions about the Galaxy past if analyses marginalize over stellar age and/or birth radius. It is demonstrated that the MVR in RAVE giants is consistent with being always strongly negative, when narrow bins of [Mg/Fe] are considered. This is directly related to the negative radial metallicity gradients of stars grouped by common age (mono-age populations) due to the inside-out disk formation. The effect of the asymmetric drift can then give rise to a positive MVR trend in high-[α/Fe] stars, with a slope dependent on a given survey's selection function and observational uncertainties. We also study the variation of lithium abundance, A(Li), with [Fe/H] of AMBRE:HARPS dwarfs. A strong reversal in the positive A(Li)-[Fe/H] trend of the total sample is found for mono-age populations, flattening for younger groups of stars. Dissecting by birth radius shows strengthening in the positive A(Li)-[Fe/H] trend, shifting to higher [Fe/H] with decreasing birth radius; these observational results suggest new constraints on chemical evolution models. This work highlights the necessity for precise age estimates for large stellar samples covering wide spatial regions.

show abstract

“…In this case they can be interpreted as blue straggler stars of this intermediate-age population. Their color and magnitude can also be compatible with their being thick-disk or halo foreground hot sdBs, although we do not expect so many stars of this type in such a limited volume (Carraro et al 2015). The spectroscopic data we have analyzed in this work help us to understand better the nature of these stars.…”

Section: Discussionmentioning

confidence: 87%

“…Alternatively, these stars can be the blue straggler population of the old, metal-poor population mentioned above. Finally, they can be mostly hot subdwarfs of type O and B, which are known to be present in the general Galactic field, both in the disk and in the halo (Carraro et al 2015). Obviously, better scrutiny of these different scenarios can be undertaken only via a dedicated spectroscopic study of these blue stars.…”

Section: Introductionmentioning

confidence: 99%

Galactic Structure in the Outer Disk: The Field in the Line of Sight to the Intermediate-Age open Cluster Tombaugh 1*

Carraro

Silva

Bidin

et al. 2017

Self Cite

View full text Add to dashboard Cite

We employ optical photometry and high-resolution spectroscopy to study a field toward the open cluster Tombaugh1, where we identify a complex population mixture that we describe in terms of young and old Galactic thin disks. Of particular interest is the spatial distribution of the young population, which consists of dwarfs with spectral types as early as B6 and is distributed in a blue plume feature in the color-magnitude diagram. For the first time, we confirm spectroscopically that most of these stars are early-type stars and not blue stragglers or halo/ thick-disk subdwarfs. Moreover, they are not evenly distributed along the line of sight but crowd at heliocentric distances between 6.6 and 8.2 kpc. We compare these results with present-day understanding of the spiral structure of the Galaxy and suggest that they trace the outer arm. This range of distances challenges current Galactic models adopting a disk cutoff at 14 kpc from the Galactic center. The young dwarfs overlap in space with an older component, which is identified as an old Galactic thin disk. Both young and old populations are confined in space since the disk is warped at the latitude and longitude of Tombaugh1. The main effects of the warp are that the line of sight intersects the disk and entirely crosses it at the outer arm distance and that there are no traces of the closer Perseus arm, which would then be either unimportant in this sector or located much closer to the formal Galactic plane. Finally, we analyze a group of giant stars, which turn out to be located at very different distances and to possess very different chemical properties, with no obvious relation to the other populations.

show abstract

The Thickening of the Thin Disk in the Third Galactic Quadrant

Cited by 25 publications

References 39 publications

The nearby Galaxy structure toward the Vela Gum nebula

The nearby Galaxy structure toward the Vela Gum nebula

Yule-Simpson’s paradox in Galactic Archaeology

Galactic Structure in the Outer Disk: The Field in the Line of Sight to the Intermediate-Age open Cluster Tombaugh 1*

Contact Info

Product

Resources

About