J/ApJ/887/115 Spectra of 28 stars in Price-Whelan 1 association (Nidever+, 2019)
Spectroscopy of the young stellar association Price-Whelan 1: origin in the
Magellanic Leading Arm and constraints on the Milky Way hot halo.
Nidever D.L., Price-Whelan A.M., Choi Y., Beaton R.L., Hansen T.T.,
Boubert D., Aguado D., Ezzeddine R., Oh S., Evans N.W.
<Astrophys. J., 887, 115-115 (2019)>
=2019ApJ...887..115N 2019ApJ...887..115N (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open; Spectra, optical; Abundances, [Fe/H];
Velocity dispersion
Keywords: Open star clusters; Halo stars; Magellanic Stream
High resolution spectroscopy
Abstract:
We report spectroscopic measurements of stars in the recently
discovered young stellar association Price-Whelan 1 (PW1), which was
found in the vicinity of the Leading Arm (LA) of the Magellanic Stream
(MS). We obtained Magellan+MIKE high-resolution spectra of the
28 brightest stars in PW 1 and used The Cannon to determine their
stellar parameters. We find that the mean metallicity of PW1 is
[Fe/H]=-1.23 with a small scatter of 0.06dex and the mean RV is
Vhel=276.7km/s with a dispersion of 11.0km/s. Our results are
consistent in Teff, logg, and [Fe/H] with the young and metal-poor
characteristics (116Myr and [Fe/H]=-1.1) determined for PW1 from our
discovery paper. We find a strong correlation between the spatial
pattern of the PW1 stars and the LA II gas with an offset of
-10.15° in LMS and +1.55° in BMS. The similarity in
metallicity, velocity, and spatial patterns indicates that PW1 likely
originated in LA II. We find that the spatial and kinematic separation
between LA II and PW1 can be explained by ram pressure from Milky Way
(MW) gas. Using orbit integrations that account for the LMC and MW
halo and outer disk gas, we constrain the halo gas density at the
orbital pericenter of PW1 to be
nhalo(17kpc)=2.7-2.0+3.4x10-3atoms/cm3 and the disk gas
density at the midplane at 20kpc to be
ndisk(20kpc,0)=6.0-2.0+1.5x10-2atoms/cm3. We, therefore,
conclude that PW 1 formed from the LA II of the MS, making it a
powerful constraint on the MW-Magellanic interaction.
Description:
We obtained spectra (R∼31000) for the brightest 28 Price-Whelan 1
(PW1) stars and 6 standard stars using the Magellan Inamori Kyocera
Echelle (MIKE) spectrograph on Magellan-Clay at Las Campanas
Observatory on 2019 April 25, 26, and 30 and May 1. Some of the stars
were also observed on 2018 December 26-28 using the Goodman
Spectrograph at the SOAR Telescope.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 120 28 PW 1 spectroscopic results
fig3/* . 28 Spectra in FITS format for the 28 stars
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See also:
VI/65 : Evolutionary models of evolved stars (Dorman+ 1993)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJ/419/596 : Pop I UV radiation models (Dorman+, 1993)
J/A+AS/122/463 : Carbon stars in Magellanic Clouds (Kunkel+ 1997)
J/ApJS/136/463 : Distances and metallicities of HVCs and IVCs (Wakker, 2001)
J/AJ/127/1531 : Star formation history of SMC (Harris+, 2004)
J/ApJ/649/201 : Velocities & Washington phot. in Carina dSph (Munoz+, 2006)
J/AJ/138/1243 : The star formation history of the LMC (Harris+, 2009)
J/ApJS/197/16 : CO observations of LMC molecular clouds (MAGMA). (Wong+, 2011)
J/ApJ/764/74 : GASS HVCs in the Magellanic Leading Arm region (For+, 2013)
J/ApJ/808/16 : Cannon, a new approach to determine abundances (Ness+, 2015)
J/AJ/153/257 : Comoving stars in Gaia DR1 (Oh+, 2017)
J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Name Name of the star
8- 26 I19 --- Gaia Gaia DR2 identifier
28- 29 I2 h RAh Hour of right ascension (J2000) (1)
31- 32 I2 min RAm Minute of right ascension (J2000)
34- 37 F4.1 s RAs Second of right ascension (J2000)
39 A1 --- DE- Sign of declination (J2000) (1)
40- 41 I2 deg DEd Degree of declination (J2000) (1)
43- 44 I2 arcmin DEm Arcminute of declination (J2000)
46- 49 F4.1 arcsec DEs Arcsecond of declination (J2000)
51- 55 F5.2 mag Gmag [15.1/18.3] Gaia G-band magnitude
57- 61 F5.2 mag BP-RP [-0.24/-0.06] BP-RP color index
63- 67 F5.2 mas/yr pmRA [-1/0.22] Proper motion in right ascension
direction (pmRA*cosDE)
69- 72 F4.2 mas/yr pmDE [0.18/0.61] Proper motion in declination
direction
74- 77 F4.1 --- S/N [4.3/38.1] Signal-to-noise ratio
79- 83 F5.1 km/s Vlsr [235.1/341.6] Local Standard of Rest
velocity
85- 88 F4.1 km/s sigma [2.7/20] Velocity dispersion σV
90- 94 I5 K Teff [13570/17930] Effective temperature
96- 99 I4 K e_Teff [189/2041] Teff uncertainty
101- 104 F4.2 [cm/s2] logg [2.25/4.19] Log of surface gravity
106- 109 F4.2 [cm/s2] e_logg [0.04/0.36] Logg uncertainty
111- 115 F5.2 [Sun] [Fe/H] [-1.32/-0.33] Abundance of [Fe/H]
117- 120 F4.2 [Sun] e_[Fe/H] [0.02/0.57] [Fe/H] uncertainty
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Note (1): Coordinates from the FITS Headers with not accurate declinations;
ignored in VizieR.
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Acknowledgements:
Nidever David <david.nidever at montana.edu>
History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 27-May-2021