J/ApJ/776/26 RRab stars in the Orphan stream distances (Sesar+, 2013)
Tracing the Orphan stream to 55 kpc with RR Lyrae stars.
Sesar B., Grillmair C.J., Cohen J.G., Bellm E.C., Bhalerao V.B.,
Levitan D., Laher R.R., Ofek E.O., Surace J.A., Tang S., Waszczak A.,
Kulkarni S.R., Prince T.A.
<Astrophys. J., 776, 26 (2013)>
=2013ApJ...776...26S 2013ApJ...776...26S
ADC_Keywords: Stars, distances ; Stars, variable ; Radial velocities ;
Proper motions ; Extinction
Keywords: Galaxy: halo; Galaxy: kinematics and dynamics; Galaxy: structure;
stars: variables: RR Lyrae
Abstract:
We report positions, velocities, and metallicities of 50 ab-type RR
Lyrae (RRab) stars observed in the vicinity of the Orphan stellar
stream. Using about 30 RRab stars classified as being likely members
of the Orphan stream, we study the metallicity and the spatial extent
of the stream. We find that RRab stars in the Orphan stream have a
wide range of metallicities, from -1.5dex to -2.7dex. The average
metallicity of the stream is -2.1dex, identical to the value obtained
by Newberg et al. (2010ApJ...711...32N 2010ApJ...711...32N) using blue horizontal branch
stars. We find that the most distant parts of the stream (40-50kpc
from the Sun) are about 0.3dex more metal-poor than the closer parts
(within ∼30kpc), suggesting a possible metallicity gradient along the
stream's length. We have extended the previous studies and have mapped
the stream up to 55kpc from the Sun. Even after a careful search, we
did not identify any more distant RRab stars that could plausibly be
members of the Orphan stream. If confirmed with other tracers, this
result would indicate a detection of the end of the leading arm of the
stream. We have compared the distances of Orphan stream RRab stars
with the best-fit orbits obtained by Newberg et al. We find that
model 6 of Newberg et al. cannot explain the distances of the most
remote Orphan stream RRab stars, and conclude that the best fit to
distances of Orphan stream RRab stars and to the local circular
velocity is provided by potentials where the total mass of the Galaxy
within 60kpc is M60∼2.7x1011M☉, or about 60% of the mass
found by previous studies. More extensive modeling that would consider
non-spherical potentials and the possibility of misalignment between
the stream and the orbit is highly encouraged.
Description:
The RRab stars used in this paper come from three synoptic surveys:
the Catalina Real-Time Sky Survey (CRTS, Drake et al. 2009,
J/ApJ/696/870; uses three telescopes: Catalina Sky Survey 0.7m Schmidt
(CSS), the Mount Lemmon Survey 1.5m (MLS), and the Siding Spring
Survey 0.5m Schmidt (SSS)), Lincoln Near Earth Asteroid Research
(LINEAR) survey (Stokes et al. 2000Icar..148...21S 2000Icar..148...21S; uses two
telescopes at the White Sands Missile Range), and the Palomar
Transient Factory (PTF; Law et al. 2009PASP..121.1395L 2009PASP..121.1395L; Rau et al.
2009PASP..121.1334R 2009PASP..121.1334R; uses 48 inch Samuel Oschin Schmidt Telescope on
Mount Palomar).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table13.dat 132 50 Positions, light curve parameters, line-of-sight
velocities, proper motions, and metallicities
of RR Lyrae targets (tables 1 and 3)
table2.dat 71 44 Positions and light curve parameters of CSS RRab
stars without spectroscopic observations
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See also:
II/313 : Palomar Transient Factory (PTF) photometric catalog 1.0 (Ofek+, 2012)
III/176 : RR Lyrae Metallicities (Layden 1994)
J/AJ/146/21 : LINEAR. II. Catalog of RR Lyrae stars (Sesar+, 2013)
J/ApJ/765/154 : RR Lyrae stars in the Catalina Sky Survey (Drake+, 2013)
J/ApJ/763/32 : Galactic halo RRab stars from CSS (Drake+, 2013)
J/AJ/144/114 : Radial velocities of 6 field RR Lyrae (Sesar+, 2012)
J/ApJ/752/42 : BV time series in Ursa Major II (Dall'Ora+, 2012)
J/ApJ/740/65 : VLA search for 5GHz radio transients (Ofek+, 2011)
J/ApJ/731/4 : Galactic halo as seen by the CFHTLS (Sesar+, 2011)
J/AJ/141/90 : SEGUE stellar parameter pipeline. V. (Lee+, 2011)
J/ApJ/708/717 : Light curve templates of RR Lyrae stars (Sesar+, 2010)
J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)
J/MNRAS/396/553 : Galactic RR Lyrae data (Dambis, 2009)
J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)
J/AJ/136/1645 : Spectroscopy of bright QUEST RR Lyrae stars (Vivas+, 2008)
J/ApJ/684/1143 : BHB candidates in the Milky Way (Xue+, 2008)
J/ApJ/670/346 : M giant stars in the Sagittarius dwarf gal. V. (Chou+, 2007)
J/MNRAS/380/281 : Faint galactic satellites spectrosc. survey (Martin+, 2007)
J/AJ/132/714 : QUEST RR Lyrae survey. II. Halo overdensities (Vivas+, 2006)
J/AJ/127/3034 : Proper-motion catalog combining USNO-B and SDSS (Munn+, 2004)
J/AJ/127/899 : Blue HB stars in SDSS (Sirko+, 2004)
J/A+AS/125/321 : RR Lyrae radial velocities and [Fe/H] II. (Solano+ 1997)
J/AJ/108/1016 : Kinematics of local RR lyrae stars. I. (Layden, 1994)
http://crts.caltech.edu/ : The Catalina Real-Time Transient Survey home page
http://astroweb.lanl.gov/lineardb : LINEAR Survey photometric database
http://www.ptf.caltech.edu/iptf : Intermediate Palomar Transient Factory page
Byte-by-byte Description of file: table13.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Name RR Lyrae identifier (RR0-RR49)
6- 15 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
17- 25 F9.6 deg DEdeg Declination in decimal degrees (J2000)
27- 32 A6 --- Survey Survey (CSS, LINEAR or PTF;
see the "Description" section above)
34- 37 F4.1 kpc Dist [19.5/55] Heliocentric distance
39- 44 F6.3 mag [17.1/19.1] Flux-averaged magnitude (G1)
46- 50 F5.3 mag Ar [0.03/0.4] SDSS r band extinction (G2)
52- 55 F4.2 mag Amp [0.3/1.1] Amplitude
57- 61 F5.2 mag mag0 [16.7/18.6] Magnitude at epoch of maximum
brightness
63- 70 F8.6 d Per [0.46/0.76] Period of pulsation
72- 83 F12.6 d HJD Reduced Heliocentric Julian Date of maximum
brightness; HJD-2400000
85- 90 F6.1 km/s HRV [-115/248] Heliocentric velocity
92- 95 F4.1 km/s e_HRV [9/22] Uncertainty in HRV
97-102 F6.1 km/s VGSR Galactic standard of rest velocity, assuming
the solar motion (10.1,224,6.7)km/s
104-108 F5.2 mas/yr pmGLON [-6/10] Proper motion along Galactic longitude
110-114 F5.2 mas/yr pmGLAT [-8/5] Proper motion along Galactic latitude
116-119 F4.2 mas/yr e_pm [2.4/3.6] Error in each proper motion
121-125 F5.2 [Sun] [Fe/H] [-2.8/-1.3] Metallicity
127-132 A6 --- Mm Probability of being a Orphan stream member:
"high", "medium" or "low"
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
12- 20 F9.6 deg DEdeg Declination in decimal degrees (J2000)
22- 25 F4.1 kpc Dist [30.2/71] Heliocentric distance (1)
27- 32 F6.3 mag [17.8/19.8] Flux-averaged magnitude (G1)
34- 38 F5.3 mag Ar [0.03/0.2] SDSS r band extinction (G2)
40- 43 F4.2 mag Amp [0.3/1.2] Amplitude
45- 49 F5.2 mag mag0 [17.2/19.2] Magnitude at epoch of maximum
brightness
51- 58 F8.6 d Per [0.45/0.78] Period of pulsation
60- 71 F12.6 d HJD Reduced Heliocentric Julian Date of maximum
brightness; HJD-2400000
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Note (1): Calculated assuming [Fe/H]=-2.0dex and MRR=0.47mag.
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Global notes:
Note (G1): Corrected for interstellar medium extinction and a magnitude offset
with respect to SDSS r-band, as =notcorrected-Ar-Δ;
see Section 2.2.
Note (G2): Using the Schlegel et al. (1998ApJ...500..525S 1998ApJ...500..525S) dust map.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 18-Mar-2015