The spheroidal bulge of the Milky Way: Chemodynamically distinct from the inner-thick disc and bar

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Volume 707 (March 2026)

A&A, 707 (2026) A190

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Table 2

Orbital and kinematic properties for the three Galactic components in bins of metallicity.

	[Fe/H] ∈	[−2.5, −1.0]	[−1.0, −0.5]	[−0.5, −0.25]	[−0.25, 0.0]	[0.0, 0.25]	[0.25, 0.7]
Sph. Bulge	${Z_{m a x}}_{Q 1}^{Q 3}$ $Mathematical equation: ${Z_{\mathrm{max}}}^{Q3}_{Q1}$$	${2.6}_{1.9}^{2.9}$ $Mathematical equation: $2.6^{2.9}_{1.9}$$	${2.0}_{1.6}^{2.5}$ $Mathematical equation: $2.0^{2.5}_{1.6}$$	${1.7}_{1.3}^{2.2}$ $Mathematical equation: $1.7^{2.2}_{1.3}$$	${1.4}_{1.1}^{1.8}$ $Mathematical equation: $1.4^{1.8}_{1.1}$$	${1.3}_{1.1}^{1.7}$ $Mathematical equation: $1.3^{1.7}_{1.1}$$	${1.2}_{1.0}^{1.6}$ $Mathematical equation: $1.2^{1.6}_{1.0}$$
	${R_{a p o}}_{Q 1}^{Q 3}$ $Mathematical equation: ${R_{\mathrm{apo}}}^{Q3}_{Q1}$$	${3.8}_{2.9}^{4.4}$ $Mathematical equation: $3.8^{4.4}_{2.9}$$	${3.1}_{2.1}^{4.1}$ $Mathematical equation: $3.1^{4.1}_{2.1}$$	${2.6}_{1.8}^{3.3}$ $Mathematical equation: $2.6^{3.3}_{1.8}$$	${2.0}_{1.5}^{2.8}$ $Mathematical equation: $2.0^{2.8}_{1.5}$$	${1.9}_{1.4}^{2.4}$ $Mathematical equation: $1.9^{2.4}_{1.4}$$	${1.8}_{1.2}^{2.5}$ $Mathematical equation: $1.8^{2.5}_{1.2}$$
	V_φ	3 ± 4	9 ± 3	3 ± 4	4 ± 7	−5 ± 7	−7 ± 5
	σ_{V_φ}	57 ± 5	62 ± 3	63 ± 4	69 ± 5	72 ± 7	59 ± 7
	σ_{V_R}	85 ± 4	101 ± 3	111 ± 5	109 ± 7	111 ± 8	110 ± 7
	σ_{V_Z}	89 ± 5	92 ± 3	95 ± 4	98 ± 6	109 ± 7	96 ± 6
Disc	${Z_{m a x}}_{Q 1}^{Q 3}$ $Mathematical equation: ${Z_{\mathrm{max}}}^{Q3}_{Q1}$$	${2.0}_{1.7}^{2.3}$ $Mathematical equation: $2.0^{2.3}_{1.7}$$	${1.7}_{1.5}^{2.1}$ $Mathematical equation: $1.7^{2.1}_{1.5}$$	${1.5}_{1.4}^{1.8}$ $Mathematical equation: $1.5^{1.8}_{1.4}$$	${1.4}_{1.0}^{1.6}$ $Mathematical equation: $1.4^{1.6}_{1.0}$$	${1.0}_{0.5}^{1.4}$ $Mathematical equation: $1.0^{1.4}_{0.5}$$	${1.3}_{0.6}^{1.5}$ $Mathematical equation: $1.3^{1.5}_{0.6}$$
	${R_{a p o}}_{Q 1}^{Q 3}$ $Mathematical equation: ${R_{\mathrm{apo}}}^{Q3}_{Q1}$$	${4.5}_{4.1}^{4.8}$ $Mathematical equation: $4.5^{4.8}_{4.1}$$	${4.5}_{4.2}^{4.8}$ $Mathematical equation: $4.5^{4.8}_{4.2}$$	${4.6}_{4.3}^{4.8}$ $Mathematical equation: $4.6^{4.8}_{4.3}$$	${4.6}_{4.3}^{4.8}$ $Mathematical equation: $4.6^{4.8}_{4.3}$$	${4.7}_{4.4}^{4.9}$ $Mathematical equation: $4.7^{4.9}_{4.4}$$	${4.5}_{4.0}^{4.8}$ $Mathematical equation: $4.5^{4.8}_{4.0}$$
	V_φ	127 ± 4	131 ± 2	135 ± 2	139 ± 2	141 ± 3	127 ± 4
	σ_{V_φ}	41 ± 3	40 ± 1	43 ± 2	39 ± 2	38 ± 2	36 ± 3
	σ_{V_R}	80 ± 5	68 ± 2	65 ± 2	63 ± 3	65 ± 4	86 ± 5
	σ_{V_Z}	76 ± 5	67 ± 2	63 ± 2	53 ± 3	43 ± 3	56 ± 5
Bar	${Z_{m a x}}_{Q 1}^{Q 3}$ $Mathematical equation: ${Z_{\mathrm{max}}}^{Q3}_{Q1}$$	${1.0}_{0.8}^{1.5}$ $Mathematical equation: $1.0^{1.5}_{0.8}$$	${1.0}_{0.7}^{1.2}$ $Mathematical equation: $1.0^{1.2}_{0.7}$$	${0.9}_{0.7}^{1.2}$ $Mathematical equation: $0.9^{1.2}_{0.7}$$	${0.9}_{0.7}^{1.1}$ $Mathematical equation: $0.9^{1.1}_{0.7}$$	${0.8}_{0.6}^{1.0}$ $Mathematical equation: $0.8^{1.0}_{0.6}$$	${0.9}_{0.7}^{1.1}$ $Mathematical equation: $0.9^{1.1}_{0.7}$$
	${R_{a p o}}_{Q 1}^{Q 3}$ $Mathematical equation: ${R_{\mathrm{apo}}}^{Q3}_{Q1}$$	${2.5}_{1.4}^{3.4}$ $Mathematical equation: $2.5^{3.4}_{1.4}$$	${2.3}_{1.5}^{3.3}$ $Mathematical equation: $2.3^{3.3}_{1.5}$$	${2.7}_{1.7}^{3.4}$ $Mathematical equation: $2.7^{3.4}_{1.7}$$	${2.6}_{1.7}^{3.6}$ $Mathematical equation: $2.6^{3.6}_{1.7}$$	${2.2}_{1.5}^{3.1}$ $Mathematical equation: $2.2^{3.1}_{1.5}$$	${2.2}_{1.5}^{2.7}$ $Mathematical equation: $2.2^{2.7}_{1.5}$$
	V_φ	100 ± 10	107 ± 4	118 ± 4	120 ± 4	107 ± 4	98 ± 3
	σ_{V_φ}	55 ± 6	62 ± 2	58 ± 2	58 ± 3	58 ± 3	55 ± 2
	σ_{V_R}	67 ± 9	72 ± 3	66 ± 3	71 ± 4	79 ± 3	76 ± 2
	σ_{V_Z}	73 ± 7	68 ± 3	65 ± 3	64 ± 3	60 ± 3	65 ± 2

Notes. The table lists orbital (Z_max and R_apo) and kinematic (V_φ, σ_{V_φ}, σ_{V_R}, and σ_{V_Z}) properties for the spheroidal bulge, the disc and the bar components in bins of metallicity. For Z_max and R_apo the median together with the first and third quartiles of the distribution are listed. The mean azimuthal velocity (V_φ), as well as the azimuthal (σ_{V_φ}), radial (σ_{V_R}), and vertical (σ_{V_Z}) velocity dispersions and their respective uncertainties, estimated via a bootstrap sampling, are also shown.

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