Query : 2019A&A...627A...3L

2019A&A...627A...3L - Astronomy and Astrophysics, volume 627A, 3-3 (2019/7-1)

Distribution of red clump stars does not support the X-shaped Galactic bulge.


Abstract (from CDS):

Context. Claims of an X-shaped Galactic bulge were based on the assumption of red clump stars as standard candles in some lines of sight crossing the off-plane bulge. However, some doubts have been cast on whether the two peaks in star counts along the line of sight really represent a double peak in the density distribution, or whether there is something wrong with the assumption of a unique constant absolute magnitude for all of these stars. Aims. With the advent of Gaia-DR2 parallaxes in combination with near-infrared VISTA-VVV data, we are able to check which of the hypotheses is correct. Methods. We calculated the median absolute magnitude MK corresponding to both peaks of putative red clumps in seven lines of sight with the lowest extinction in the interesting coordinates' range. Results. The difference between the absolute magnitude of the bright and the faint peak is ΔMK~=0.4. The selected stars in both peaks cannot be represented by the same red clump giants with constant MK~=-1.6. Conclusions. The hypothesis that the bulge contains an X-shape is based on the assumption that the faint and bright peaks of the density distribution towards the bulge are dominated by standard red clump stars. However, we show that both the faint and bright peaks cannot be dominated by standard red clump stars simultaneously.

Abstract Copyright: © ESO 2019

Journal keyword(s): Galaxy: structure - Galaxy: bulge

Simbad objects: 1

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Number of rows : 1
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NAME Galactic Bulge reg ~ ~           ~ 4169 0

Query : 2019A&A...627A...3L

Basic data :
NAME Galactic Bulge -- Region defined in the Sky
Origin of the objects types :

(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases

Other object types:
reg ()
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
ICRS coord. (ep=J2000) :
No Coord.

The link on the acronym of the identifiers give access to the information for this acronym in the dictionary of nomenclature.
Identifiers (2) :
An access of full data is available using the icon Vizier near the identifier of the catalogue

NAME Gal Bulge NAME Galactic Bulge

References (4169 between 1850 and 2023) (Total 4169)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).
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Observing logs

ISO : 10   


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