Research

From open clusters in the outer Milky Way disk to tidal streams in galaxies at 100 Mpc, my research centers on objects that are at overall low stellar density. I study these objects with resolved stellar photometry, integrated light photometry, stellar spectroscopy, and sometimes the gas dynamics with neutral hydrogen. I use all wavebands -- the UV, optical, near-infrared, mid-infrared, and even the radio. I have traveled to telescopes very large (GBT), reasonably large (Keck, LBT, Gemini), medium (Mayall 4-meter), and small (VATT, KPNO 2.1 meter).

Here (PDF) is a high-level discussion of my research at the conclusion of my graduate degree in 2014.

The Carnegie-Chicago Hubble Program (CCHP):

In the CCHP2, we aim to measure the Hubble constant entirely with Population II -- using RR Lyrae in the Local Group and the tips of the red giant branch from the Local Group and to SNe 1a hosts, and the SNe 1a hosts into the Hubble Flow. The hope is that a distance ladder built entirely on techniques independent of the traditional Cepheid based distance ladder will help to resolve or at least better understand the current 2-sigma tension between near and far field estimates of the Hubble constant.

The Population II distance ladder, however, requires a great deal of foundational work to be an effective means of building a three-dimensional view of our Local Universe. My post-doctoral position is about doing this foundational work -- from building light curves for nearby RR Lyrae calibrators, building a sample of Galactic TRGB calibrators, and then using these to measure high precision distances (at the 5% level or better) for Local Group and Local Volume Galaxies. There is a lot to do and I find it invigorating to be part of something that so directly uses our stellar backyard to measure properties of the Universe.

Read more in professional Articles:

1. Beaton et al. (accepted to ApJ): The Carnegie-Chicago Hubble Program. I. A New Approach to the Distance Ladder Using Only Distance Indicators of Population II
   1. Monson, Beaton et al. (submitted to AAS Journals): Standard Galactic Field RR Lyrae. I. Optical to Mid-Infrared Phased Photometry
   2. Beaton, Monson et al. (in prep): Standard Galactic Field RR Lyrae. II. Predictive Templates
   3. Beaton et al. (in prep): Old-Aged Stellar Population Distance Indicators, Book Chapter for 'Distances in the Space Age'
   4. Hatt*, Beaton, et al. (in prep): The Carnegie-Chicago Hubble Program. II. Comparing the Population I and Population II Distance Ladders in IC1613
2. Beaton, Gupta* (in prep): The Spitzer Mass Assembly of the Stellar Halo Program: The Mean Distance to the Sagittarius Core with RR Lyrae in the Mid-Infrared
3. Jang*, Beaton, et al. (in prep): The Carnegie-Chicago Hubble Program. III. The Distance to NGC1365 Using the TRGB
4. ... and more on the way!

*Graduate or Undergraduate student.

Read more in my Public Presentations (most of my presentations on this topic are not publicly accessible at this time):

1. That Other Way to Measure H0:A Perspective for Precision Distances in the NIR with WFIRST
   1. Community Astrophysics with WFIRST: Guest Observer & Archival Science
   2. Pasadena, CA; March 2016

The M31 Asymptotic Giant Extended Survey (M31AGES):

Recent large-scale surveys of M31 have enabled the study of its satellites, smooth halo, and substructure in exquisite detail. In particular, the Spectroscopic Landscape of Andromeda's Stellar Halo (SPLASH) survey has obtained moderate resolution optical spectra with the DEIMOS spectrograph on the Keck II/10-m telescope, and optical photometry from various ground-based telescopes. These data have been used to map the kinematics and metallicity distributions in the dSphs and dEs, detect and characterize substructure, and study the large-scale radial surface brightness and metallicity profiles of the "smooth" halo. Notwithstanding this progress [or] In spite of these advances, there are a number of outstanding questions that cannot be answered with these data alone, including the fraction of the halo that was formed in situ vs by accretion, and the degeneracy between massive early accretion events and less massive recent accretion events. The M31 Asymptotic Giant Extended Survey (M31AGES) aims to address these questions by using NIR photometry to identify intermediate-age AGB stars in the satellites, streams, and smooth halo of M31.

We can identify AGB stars using the weird features in their spectral light distribution. These produce 'weird' colors that differentiate the stars. Below is an example from Hamren et al. of a Carbon star spectrum that demonstrates how not-like-the-spectra-you-are-looking-for these stars are:

Read More in Professional Articles --

1. Recent Results from SPLASH: Chemical Abundances and Kinematics of Andromeda's Stellar Halo -- Gilbert, Beaton & Dorman (2016 -- IAU Conference Proceeding)
1. The Metallicity Profile of the M31 Stellar Halo from Spectroscopic Members -- Gilbert et al. incl RB (2014)
2. The Surface Brightness Profile of the M31 Stellar Halo from Spectroscopic Members -- Gilbert et al. incl RB (2012
3. Dynamical Masses for 15 M31 Dwarf Satellites -- Tollerud, Beaton et al. (2012)
4. Discovery of Andromeda XIV -- Majewski, Beaton et al. (2007)

Read More in Press Releases/Other Public Communication --

1. Proper Motion of M31 (2012): UVA Press Release, AstroBites, NASA Press Release
2. The leader of the project, Roeland van der Marel has a full list of media coverage here.
3. Discovery of the Metal Poor Halo (2007): UVA Press Release, CNN, BBC, EurekaAlert!

Dwarfs in Distress:

I am seeking out the the youngest disrupting satellite galaxies -- i.e., those satellites recently accreted and that maintain some memory of their earlier lives as non-satellite dwarf galaxies. These systems are important because all observational evidence suggests that dwarf satellites loose their gas reservoirs (i.e., their future potential for star formation) very quickly (with in ~1 Gyr of infall) relatively to their survival time in their parent halo. This is evident by the density-morphology relationship for dwarf satellites in the Local Group. Only large and/or recently accreted satellites have any cold gas (these being the LMC/SMC and M33) and only those galaxies outside of the viral radius of the host have any gas (Rprojected > 300 kpc). There are galaxies that break these rules in the Local Group and these galaxies are probably trying to tell us something.

Read More in Professional Articles --

1. Tidal Streams in External Galaxies -- Carlin, Beaton, Martinez-Delgado & Gabany (2016) - Book Chapter/Review
1. The Stellar Stream & Star Formation Region in NGC5387 -- Beaton et al. 2014
2. A Tidal Stream in the Whale Galaxy (NGC4631) -- Martinez-Delgado, incl. RB, et al 2015

Take a look at my Publically Accessible Presentations --

1. Rethinking the Narrative of a Micro-Merger: Impacts on the Host Galaxy Morphology
   1. Mapping the Pathways of Galaxy Transformation Across Time and Space
   2. Catalina Island, CA; August 2016
   3. Also a member of the Local Organizing Committee
2. Rethinking the Narrative of a Micro-Merger: Tidal Debris with On-Going Star Formation
   1. The Formation and Evolution of Galaxy Outskirts
   2. Toledo, Spain; March 2016
3. Caught in the Act of Quenching: Local Volume Dwarf Satellites with On-Going Star Formation
   1. Satellites and Streams in Santiago
   2. Santiago, Chile; April 2016

Detailed Structure of the Milky Way and Stellar Evolution:

In many ways, the Milky Way is the `lens' through which we view the Universe. Not only do we have to look through it to see beyond it, but we also have to use the Milky Way to put everything else in context. Thus, the Milky Way and its constituents are form the zeroth-order information required to do just about everything else. I keep at least one-foot in the Milky Way structure and stellar evolution community and try to connect these high-resolution, high-data quality observations to the others that I do to really push our understanding of more distant galaxies with resolved stellar populations.

Some Professional Articles --

1. The Early (and Ignored) Discovery of Subgiants -- Sandage, Beaton, & Majewski (2016)
2. Notable Press Articles: Carnegie Science, Gizmodo (24k Reads)
3. Open Article with 300 downloads on its day of publication (its amazing what people will read if its free!)
4. A MIR Color - Metallicity Relationship for Cepheids -- Scowcroft, (incl RB) et al. (2016)
1. Open Clusters Discovered in the Mid-Infrared -- Zasowski, Beaton, et al. (2013)
2. (High School Student Project, then Undergraduate Project)
3. The Nature of Triangulum Andromda Stellar Overdensity

Public Level Coverage:

1. The Stellar Patrons of the Bar Unearthed (2012) -- UVA Press Release

The Bar in M31 (yes, there is one!):

One of my first assignments as an undergraduate intern was to try and remove stars from the 2MASS 6x image of M31. One thing led to another and we realized that edge-on stellar bars have weird signatures. This matched perfectly to what we were seeing with the 2MASS image! So, we did some isophote modeling and some numerical simulations and there it was.

Read More in Professional Articles --

1. Unveiling the Bar -- Beaton et al. (2007)
2. Unraveling the Bar -- Athanassoula & Beaton (2006)

Public level coverage:

1. UVA Undergrads Present Work at International Conference (2007)