DELVE-ing into the Jet: A Thin Stellar Stream on a Retrograde Orbit at 30 kpc

Abstract We perform a detailed photometric and astrometric analysis of stars in the Jet stream using data from the first data release of the DECam Local Volume Exploration Survey DR1 and Gaia EDR3. We discover that the stream extends over ∼ 29° on the sky (increasing the known length by 18°), which is comparable to the kinematically cold Phoenix, ATLAS, and GD-1 streams. Using blue horizontal branch stars, we resolve a distance gradient along the Jet stream of 0.2 kpc deg−1, with distances ranging from D ⊙ ∼ 27–34 kpc. We use natural splines to simultaneously fit the stream track, width, and intensity to quantitatively characterize density variations in the Jet stream, including a large gap, and identify substructure off the main track of the stream. Furthermore, we report the first measurement of the proper motion of the Jet stream and find that it is well aligned with the stream track, suggesting the stream has likely not been significantly perturbed perpendicular to the line of sight. Finally, we fit the stream with a dynamical model and find that it is on a retrograde orbit, and is well fit by a gravitational potential including the Milky Way and Large Magellanic Cloud. These results indicate the Jet stream is an excellent candidate for future studies with deeper photometry, astrometry, and spectroscopy to study the potential of the Milky Way and probe perturbations from baryonic and dark matter substructure.

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Gaia Data Release 2

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832698 ◽

2018 ◽

Vol 616 ◽

pp. A12 ◽

Cited By ~ 265

Author(s):

◽

A. Helmi ◽

F. van Leeuwen ◽

P. J. McMillan ◽

D. Massari ◽

...

Keyword(s):

Globular Clusters ◽

Milky Way ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Proper Motions ◽

Single Plane ◽

Dwarf Spheroidal Galaxies ◽

Orbital Parameters ◽

Data Release ◽

Using Data

Context. Aims. The goal of this paper is to demonstrate the outstanding quality of the second data release of the Gaia mission and its power for constraining many different aspects of the dynamics of the satellites of the Milky Way. We focus here on determining the proper motions of 75 Galactic globular clusters, nine dwarf spheroidal galaxies, one ultra-faint system, and the Large and Small Magellanic Clouds. Methods. Using data extracted from the Gaia archive, we derived the proper motions and parallaxes for these systems, as well as their uncertainties. We demonstrate that the errors, statistical and systematic, are relatively well understood. We integrated the orbits of these objects in three different Galactic potentials, and characterised their properties. We present the derived proper motions, space velocities, and characteristic orbital parameters in various tables to facilitate their use by the astronomical community. Results. Our limited and straightforward analyses have allowed us for example to (i) determine absolute and very precise proper motions for globular clusters; (ii) detect clear rotation signatures in the proper motions of at least five globular clusters; (iii) show that the satellites of the Milky Way are all on high-inclination orbits, but that they do not share a single plane of motion; (iv) derive a lower limit for the mass of the Milky Way of 9.1-2.6+6.2 × 1011 M⊙ based on the assumption that the Leo I dwarf spheroidal is bound; (v) derive a rotation curve for the Large Magellanic Cloud based solely on proper motions that is competitive with line-of-sight velocity curves, now using many orders of magnitude more sources; and (vi) unveil the dynamical effect of the bar on the motions of stars in the Large Magellanic Cloud. Conclusions. All these results highlight the incredible power of the Gaia astrometric mission, and in particular of its second data release.

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Local RR Lyrae stars: native and alien

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3580 ◽

2019 ◽

Vol 492 (2) ◽

pp. 2161-2176 ◽

Cited By ~ 2

Author(s):

R Zinn ◽

X Chen ◽

A C Layden ◽

D I Casetti-Dinescu

Keyword(s):

Milky Way ◽

Large Magellanic Cloud ◽

Rr Lyrae Stars ◽

Rr Lyrae ◽

Angular Momenta ◽

Data Release ◽

Total Energies ◽

Using Data ◽

Lyrae Stars ◽

Existing Data

ABSTRACT Measurements of [Fe/H] and radial velocity are presented for 89 RR Lyrae (RRL) candidates within 6 kpc of the Sun. After the removal of two suspected non-RRLs, these stars were added to an existing data base, which yielded 464 RRLs with [Fe/H] on a homogeneous scale. Using data from the Gaia satellite (Data Release 2), we calculated the positions and space velocities for this sample. These data confirm the existence of a thin disc of RRL with [α/Fe] ∼ solar. The majority of the halo RRLs with large total energies have near-zero angular momenta about the Z-axis. Kinematically, these stars closely resemble the Gaia-Sausage/Gaia-Enceladus stars that others have proposed are debris from the merger of a large galaxy with the Milky Way. The metallicity and period distributions of the RRLs and their positions in the period–amplitude diagram suggest that this disrupted galaxy was as massive as the Large Magellanic Cloud and possibly greater.

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The mass of the Milky Way out to 100 kpc using halo stars

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3984 ◽

2020 ◽

Author(s):

Alis J Deason ◽

Denis Erkal ◽

Vasily Belokurov ◽

Azadeh Fattahi ◽

Facundo A Gómez ◽

...

Keyword(s):

Distribution Function ◽

Mass Concentration ◽

Milky Way ◽

Function Analysis ◽

Large Magellanic Cloud ◽

Systematic Bias ◽

Cosmological Simulations ◽

Halo Stars ◽

Systematic Effects ◽

Mass Estimate

Abstract We use a distribution function analysis to estimate the mass of the Milky Way out to 100 kpc using a large sample of halo stars. These stars are compiled from the literature, and the vast majority ($\sim \! 98\%$) have 6D phase-space information. We pay particular attention to systematic effects, such as the dynamical influence of the Large Magellanic Cloud (LMC), and the effect of unrelaxed substructure. The LMC biases the (pre-LMC infall) halo mass estimates towards higher values, while realistic stellar halos from cosmological simulations tend to underestimate the true halo mass. After applying our method to the Milky Way data we find a mass within 100 kpc of M( < 100kpc) = 6.07 ± 0.29(stat.) ± 1.21(sys.) × 1011M⊙. For this estimate, we have approximately corrected for the reflex motion induced by the LMC using the Erkal et al. model, which assumes a rigid potential for the LMC and MW. Furthermore, stars that likely belong to the Sagittarius stream are removed, and we include a 5% systematic bias, and a 20% systematic uncertainty based on our tests with cosmological simulations. Assuming the mass-concentration relation for Navarro-Frenk-White haloes, our mass estimate favours a total (pre-LMC infall) Milky Way mass of M200c = 1.01 ± 0.24 × 1012M⊙, or (post-LMC infall) mass of M200c = 1.16 ± 0.24 × 1012 M⊙ when a 1.5 × 1011M⊙ mass of a rigid LMC is included.

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Chemical Abundances of Seven Outer Halo M31 Globular Clusters from the Pan-Andromeda Archaeological Survey

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316011200 ◽

2016 ◽

Vol 11 (S321) ◽

pp. 10-12

Author(s):

Charli M. Sakari

Keyword(s):

Globular Clusters ◽

Milky Way ◽

Dwarf Galaxy ◽

Large Magellanic Cloud ◽

Archaeological Survey ◽

Chemical Abundances ◽

Light Spectra ◽

Sigma Level ◽

Stellar Streams ◽

Detailed Chemical

AbstractObservations of stellar streams in M31’s outer halo suggest that M31 is actively accreting several dwarf galaxies and their globular clusters (GCs). Detailed abundances can chemically link clusters to their birth environments, establishing whether or not a GC has been accreted from a satellite dwarf galaxy. This talk presents the detailed chemical abundances of seven M31 outer halo GCs (with projected distances from M31 greater than 30 kpc), as derived from high-resolution integrated-light spectra taken with the Hobby Eberly Telescope. Five of these clusters were recently discovered in the Pan-Andromeda Archaeological Survey (PAndAS)—this talk presents the first determinations of integrated Fe, Na, Mg, Ca, Ti, Ni, Ba, and Eu abundances for these clusters. Four of the target clusters (PA06, PA53, PA54, and PA56) are metal-poor ([Fe/H] < -1.5), α-enhanced (though they are possibly less alpha-enhanced than Milky Way stars at the 1 sigma level), and show signs of star-to-star Na and Mg variations. The other three GCs (H10, H23, and PA17) are more metal-rich, with metallicities ranging from [Fe/H] = -1.4 to -0.9. While H23 is chemically similar to Milky Way field stars, Milky Way GCs, and other M31 clusters, H10 and PA17 have moderately-low [Ca/Fe], compared to Milky Way field stars and clusters. Additionally, PA17’s high [Mg/Ca] and [Ba/Eu] ratios are distinct from Milky Way stars, and are in better agreement with the stars and clusters in the Large Magellanic Cloud (LMC). None of the clusters studied here can be conclusively linked to any of the identified streams from PAndAS; however, based on their locations, kinematics, metallicities, and detailed abundances, the most metal-rich PAndAS clusters H23 and PA17 may be associated with the progenitor of the Giant Stellar Stream, H10 may be associated with the SW Cloud, and PA53 and PA56 may be associated with the Eastern Cloud.

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Milky Way potentials in cold dark matter and MOdified Newtonian Dynamics. Is the Large Magellanic Cloud on a bound orbit?

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2008.13198.x ◽

2008 ◽

Vol 386 (4) ◽

pp. 2199-2208 ◽

Cited By ~ 67

Author(s):

Xufen Wu ◽

Benoit Famaey ◽

Gianfranco Gentile ◽

Hagai Perets ◽

HongSheng Zhao

Keyword(s):

Dark Matter ◽

Cold Dark Matter ◽

Milky Way ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Modified Newtonian Dynamics ◽

Newtonian Dynamics

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Dust Grain–Size Distributions and Extinction in the Milky Way, Large Magellanic Cloud, and Small Magellanic Cloud

The Astrophysical Journal ◽

10.1086/318651 ◽

2001 ◽

Vol 548 (1) ◽

pp. 296-309 ◽

Cited By ~ 1574

Author(s):

Joseph C. Weingartner ◽

B. T. Draine

Keyword(s):

Grain Size ◽

Milky Way ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Size Distributions ◽

Small Magellanic Cloud ◽

Grain Size Distributions ◽

Dust Grain

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The interstellar medium of the Magellanic Clouds from absorption lines

Symposium - International Astronomical Union ◽

10.1017/s0074180900201022 ◽

1991 ◽

Vol 148 ◽

pp. 401-406 ◽

Cited By ~ 2

Author(s):

Klaas S. De Boer

Keyword(s):

Interstellar Medium ◽

Absorption Line ◽

Milky Way ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Magellanic Clouds ◽

Absorption Lines ◽

Small Magellanic Cloud ◽

General Aspects

General aspects of ISM studies using absorption line studies are given and available data are reviewed. Topics are: galactic foreground gas, individual fields in the Magellanic Clouds (MCs) and MC coronae. Overall investigations are discussed. It is demonstrated that the metals in the gas of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are a factor of 3 and 10, respectively, in abundance below solar levels. The depletion pattern in the LMC is similar to that of the Milky Way.

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An ancient double degenerate merger in the Milky Way halo

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slz165 ◽

2019 ◽

Cited By ~ 3

Author(s):

Adela Kawka ◽

Stéphane Vennes ◽

Lilia Ferrario

Keyword(s):

White Dwarf ◽

Milky Way ◽

Dwarf Galaxy ◽

Red Shift ◽

High Mass ◽

Retrograde Orbit ◽

Merger Event ◽

Whole Class ◽

Milky Way Halo

Abstract We present an analysis and re-appraisal of the massive, carbon-enriched (DQ) white dwarf (WD) LP 93-21. Its high mass (≈1 M⊙) and membership to the class of warm DQ WDs, combined with its peculiar halo kinematics suggest that this object is the product of an ancient stellar merger event, most likely that of two WDs. Furthermore, the kinematics places this object on a highly retrograde orbit driven by the accretion of a dwarf galaxy onto the Milky Way that occurred at a red shift greater than 1.5. As the product of a stellar merger LP 93-21 is probably representative of the whole class of warm/hot DQ WDs.

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“2-D Frutti” Spectra of B Supergiants in the Milky Way and the LMC

Symposium - International Astronomical Union ◽

10.1017/s0074180900035695 ◽

1988 ◽

Vol 132 ◽

pp. 559-562

Author(s):

Edward L. Fitzpatrick

Keyword(s):

Milky Way ◽

Photon Counting ◽

Large Magellanic Cloud ◽

Magellanic Cloud ◽

Image Tube ◽

Blue Region ◽

Pattern Noise ◽

Fixed Pattern Noise ◽

The Individual ◽

Type Detector

Digital spectra of 7 B-type supergiants in the Milky Way and 15 B-type supergiants in the Large Magellanic Cloud (LMC) were obtained in December 1986 using the “2-D Frutti” detector (2-DF) and the Carnegie Image Tube Spectrograph on the 1-m telescope at the Cerro Tololo Inter-American Observatory. The 2-DF is a photon counting, 2-dimensional Shechtman-type detector, now available on both the 1-m and 4-m telescopes at CTIO. The detector/spectrograph configuration used for the December observing run yielded spectra covering the classical blue region, 3800-5000 Å, with a resolution of approximately 3 Å. The typical observing procedure was to obtain spectra for each star at several locations along the slit. The individual spectra were then averaged (to reduce the detector fixed pattern noise) resulting in S/N ratios of 50-60 in the 4300 Å region.

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