J/ApJ/751/130 SDSS-DR7 red HB stars spectroscopic data (Shi+, 2012)
The kinematics and chemistry of red horizontal branch stars in the Sagittarius
streams.
Shi W.B., Chen Y.Q., Carrell K., Zhao G.
<Astrophys. J., 751, 130 (2012)>
=2012ApJ...751..130S 2012ApJ...751..130S
ADC_Keywords: Stars, horizontal branch ; Abundances ; Radial velocities ;
Stars, distances
Keywords: galaxies: dwarf - Galaxy: halo - stars: abundances
Abstract:
We have selected 556 red horizontal branch stars along the streams of
the Sagittarius (Sgr) dwarf galaxy from Sloan Digital Sky Survey DR7
spectroscopic data using a theoretical model. The metallicity and
α-element distributions are investigated for stars in the Sgr
streams and for Galactic stars at the same locations. We find that the
Sgr stars have two peaks in the metallicity distribution while the
Galactic stars have a more prominent metal-poor peak. Meanwhile,
[α/Fe] ratios of the Sgr stars are lower than those of the
Galactic stars. Among the Sgr stars, we find a difference in the
metallicity distribution between the leading and trailing arms of the
Sgr tidal tails. The metallicity and [α/Fe] distribution of the
leading arm is similar to that of the Galaxy. The trailing arm is
composed mainly of a metal-rich component and [α/Fe] is
obviously lower than that of the Galactic stars. The metallicity
gradient is -(1.8±0.3)x10-3dex/deg in the first wrap of the
trailing arm and -(1.5±0.4)x10-3dex/deg in the first wrap of the
leading arm. No significant gradient exists along the second wraps of
the leading or trailing arms. It seems that the Sgr dwarf galaxy
initially lost the metal-poor component in the second wrap (older)
arms due to the tidal force of our Galaxy and then the metal-rich
component is disrupted in the first wrap (younger) arms. Finally, we
found that the velocity dispersion of the trailing arm from
88°<Λ☉<112° is σ=9.808±1.0km/s, which is
consistent with previous work in the literature.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 99 556 The Sgr sample of red horizontal-branch stars
table2.dat 99 1001 The Galactic sample of red horizontal-branch stars
--------------------------------------------------------------------------------
See also:
J/MNRAS/427/2647 : Sgr dSph stars spectral classification (McDonald+, 2012)
J/ApJ/731/119 : BHB candidates in Sagittarius stream (Ruhland+, 2011)
J/ApJ/708/1290 : A 2MASS view of the Sgr dSph. VI. (Chou+, 2010)
J/A+A/520/A95 : Abundances of red giants in M54 and Sgr dSph (Carretta+, 2010)
J/A+A/513/A62 : Sgr dSph VIMOS photometry and RVs (Giuffrida+, 2010)
J/A+A/465/815 : Abundances of Sgr dSph stars (Sbordone+, 2007)
J/A+A/464/201 : RGB stars in Sagittarius streams (Monaco+, 2007)
J/AJ/128/245 : M giant stars in the Sgr dwarf galaxy (Majewski+, 2004)
J/AJ/113/634 : The survival of Sagittarius dwarf galaxy (Ibata+ 1997)
J/AJ/110/1141 : Variables in the Sagittarius dSph (Mateo+ 1995)
Byte-by-byte Description of file: table[12].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Plate SDSS-DR7 Plate
6- 10 I5 d MJD SDSS-DR7 Modified Julian Date
12- 14 I3 --- Fiber SDSS-DR7 Fiber
16- 23 F8.4 deg RAdeg Right Ascension in decimal degrees (J2000)
25- 33 F9.5 deg DEdeg Declination in decimal degrees (J2000)
35- 39 F5.2 [Sun] [Fe/H] [-2/0] Metallicity
41- 44 F4.2 [-] [a/Fe] [0/0.5] The α/Fe abundance ratio
46- 51 F6.3 kpc Dist [7.2/62.2] Distance
53- 58 F6.1 km/s RV [-437/989] Radial velocity
60- 63 F4.1 km/s e_RV [0.6/15] Error in RV
65- 72 F8.3 km/s Vgsr Galactic Standard of Rest velocity (2)
74- 80 F7.3 deg Lambda [74/317] Longitude Λ along orbital plane
82- 88 F7.3 kpc Xgc X position relative to Galactic center
90- 96 F7.3 kpc Zgc Z position relative to Galactic center
98- 99 A2 --- Loc Location note (1)
--------------------------------------------------------------------------------
Note (1): The position in our Galaxy is:
T1 = Trailing arm 1;
T2 = Trailing arm 2;
L1 = Leading arm 1;
L2 = Leading arm 2;
O = overlap.
Note (2): a value of 220km/s is used as the rotation velocity of the LSR
in the Galactic Standard of Rest (GSR), i.e.
Vgsr = RV + 9cos(b)cos(l) + 232cos(b)sin(l) + 7sin(b)
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 16-Jan-2014