J/ApJ/660/311 Hypervelocity stars. II. (Brown+, 2007)
Hypervelocity stars. II. The bound population.
Brown W.R., Geller M.J., Kenyon S.J., Kurtz M.J., Bromley B.C.
<Astrophys. J., 660, 311-318 (2007)>
=2007ApJ...660..311B 2007ApJ...660..311B
ADC_Keywords: Surveys ; Galaxies, nearby ; Radial velocities ; Photometry, SDSS
Keywords: Galaxy: center - Galaxy: halo - Galaxy: kinematics and dynamics -
Galaxy: stellar content - stars: early-type
Abstract:
Hypervelocity stars (HVSs) are stars ejected completely out of the
Milky Way by three-body interactions with the massive black hole in
the Galactic center. We describe 643 new spectroscopic observations
from our targeted survey for HVSs. We find a significant (3.5σ)
excess of B-type stars with large velocities +275km/s<Vrf<450km/s
and distances d>10kpc that are most plausibly explained as a new class
of HVSs: stars ejected from the Galactic center on bound orbits. If a
Galactic center ejection origin is correct, the distribution of HVSs
on the sky should be anisotropic for a survey complete to a fixed
limiting apparent magnitude. The unbound HVSs in our survey have a
marginally anisotropic distribution on the sky, consistent with the
Galactic center ejection picture.
Description:
Brown et al. (2006, Cat. J/ApJ/647/303) describe our target selection
for candidate HVSs.
We have also carried out a new, complementary HVS survey targeting
bright stars with and B-type colors in the SDSS. We use the 1.5m
Tillinghast telescope and the FAST spectrograph to observe these
bright HVS candidates.
New observations at the 6.5m MMT telescope were obtained with the
Blue Channel Spectrograph on the nights of 2006 May 23-26 and 2006
June 19-20.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 49 11 Possible found High-Velocity Stars.
table2.dat 71 643 *HVS Survey: new observations
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Note on table2.dat:
Stars identified as [BGK2006] JHHMMSS.ss+DDMMSS.s in Simbad
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See also:
J/ApJ/647/303 : Spectroscopic survey of hypervelocity stars (Brown+, 2006)
J/ApJ/671/1708 : Hypervelocity stars. III (Brown+, 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [SDSS]
6- 24 A19 --- SDSS SDSS name (JHHMMSS.ss+DDMMSS.s)
26- 30 F5.1 deg Glon Galactic longitude
31- 35 F5.1 deg Glat Galactic latitude
37- 40 I4 km/s Vrf Rest-frame (galactocentric) velocity
42- 43 A2 --- Sp Spectral type
45- 46 I2 kpc Ra Galactocentric distance assuming a MS star
(main-sequence)
48- 49 I2 kpc Rb Galactocentric distance assuming a BHB star
(blue horizontal branch)
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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- 2 I2 h RAh Hour of Right Ascension (J2000)
4- 5 I2 min RAm Minute of Right Ascension (J2000)
7- 11 F5.2 s RAs Second of Right Ascension (J2000)
13 A1 --- DE- Sign of the Declination (J2000)
14- 15 I2 deg DEd Degree of Declination (J2000)
17- 18 I2 arcmin DEm Arcminute of Declination (J2000)
20- 23 F4.1 arcsec DEs Arcsecond of Declination (J2000)
25- 30 F6.3 mag g'mag Apparent g' band magnitude
32- 36 F5.3 mag e_g'mag Uncertainty in gmag
38- 42 F5.3 mag (u'-g')0 Intrinsic (u'-g') color
44- 48 F5.3 mag e_(u'-g')0 Uncertainty in (u-g)0
50- 55 F6.3 mag (g'-r')0 Intrinsic (g'-r') color
57- 61 F5.3 mag e_(g'-r')0 Uncertainty in (g-r)0
63 I1 --- WD [0/1] code 1=White dwarf, 0=B-type star
65- 68 I4 km/s HV Heliocentric velocity
70- 71 I2 km/s e_HV Uncertainty in HV
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History:
* 08-Sep-2008: From electronic version of the journal
* 01-Nov-2008: one typo corrected in table2 (declination sign)
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 08-Sep-2008