A Universal Mass Profile for Dwarf Spheroidal Galaxies? (2009)
Walker, Matthew G., Mateo, Mario, Olszewski, Edward W., Peñarrubia, Jorge, Evans, N. Wyn, Gilmore, Gerard
(abridged) We apply the Jeans equation to estimate masses for eight of the brightest dSph galaxies. For Fornax we obtain a model-independent constraint on the maximum-circular velocity,...
The ACS Nearby Galaxy Survey Treasury (2009)
Dalcanton, Julianne J., Williams, Benjamin F., Seth, Anil C., Dolphin, Andrew, Holtzman, Jon, Rosema, Keith, ...
The ACS Nearby Galaxy Survey Treasury (ANGST) is a systematic survey to establish a legacy of uniform multi-color photometry of resolved stars for a volume-limited sample of nearby galaxies (D14...
Streaming motion in Leo I (2009)
Sen, Bodhisattva, Banerjee, Moulinath, Woodroofe, Michael, Mateo, Mario, Walker, Matthew
Whether a dwarf spheroidal galaxy is in equilibrium or being tidally disrupted by the Milky Way is an important question for the study of its dark matter content and distribution. This question is...
Mapping the Galactic Halo VIII: Quantifying substructure (2009)
Starkenburg, Else, Helmi, Amina, Morrison, Heather L., Harding, Paul, Van Woerden, Hugo, Mateo, Mario, ...
We have measured the amount of kinematic substructure in the Galactic halo using the final data set from the Spaghetti project, a pencil-beam high latitude sky survey. Our sample contains 101...
Leo V: Spectroscopy of a Distant and Disturbed Satellite (2009)
Walker, Matthew G., Belokurov, Vasily, Evans, N. Wyn, Irwin, Michael J., Mateo, Mario, Olszewski, Edward W., ...
We present a spectroscopic study of Leo V, a recently discovered satellite of the Milky Way (MW). From stellar spectra obtained with the MMT/Hectochelle spectrograph we identify seven likely members...
Walker, Matthew G., Mateo, Mario, Olszewski, Edward W., Sen, Bodhisattva, Woodroofe, Michael
(abridged) We develop an algorithm for estimating parameters of a distribution sampled with contamination, employing a statistical technique known as ``expectation maximization'' (EM). Given models...
Walker, Matthew G., Mateo, Mario, Olszewski, Edward
We present spectroscopic data for individual stars observed from 2004 March through 2008 August as part of our Michigan/MIKE Fiber System (MMFS) survey of four dwarf spheroidal (dSph) galaxies:...
The ACS Nearby Galaxy Survey Treasury I. The Star Formation History of the M81 Outer Disk (2008)
Williams, Benjamin F., Dalcanton, Julianne J., Seth, Anil C., Weisz, Daniel, Dolphin, Andrew, Skillman, Evan, ...
The ACS Nearby Galaxy Survey Treasury (ANGST) is a large Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) treasury program to obtain resolved stellar photometry for a volume-limited...
Walker, Matthew G., Mateo, Mario, Olszewski, Edward W.
The transverse motions of nearby dwarf spheroidal (dSph) galaxies contribute line-of-sight components that increase with angular distance from the dSph centers, inducing detectable gradients in...
Variable stars in the Fornax dSph Galaxy. II. Pulsating stars below the horizontal branch (2008)
Poretti, Ennio, Clementini, Gisella, Held, Enrico V, Greco, Claudia, Mateo, Mario, Dell'Arciprete, Luca, ...
We have carried out an intensive survey of the northern region of the Fornax dwarf spheroidal galaxy with the aim of detecting the galaxy's short--period pulsating stars (P
Variable stars in the Fornax dSph Galaxy. II. Pulsating stars below the horizontal branch (2008)
Poretti, Ennio, Clementini, Gisella, Held, Enrico V., Greco, Claudia, Mateo, Mario, Dell'Arciprete, Luca, ...
We have carried out an intensive survey of the northern region of the Fornax dwarf spheroidal galaxy with the aim of detecting the galaxy's short--period pulsating stars (P
Bernard, Edouard J., Gallart, Carme, Monelli, Matteo, Aparicio, Antonio, Cassisi, Santi, Skillman, Evan D., ...
We present a study of the radial distribution of RR Lyrae variables, which present a range of photometric and pulsational properties, in the dwarf spheroidal galaxy Tucana. We find that the fainter...
Mario Mateo, Edward W. Olszewski, K. H. Cook
The High Resolution Echelle Spectrometer on the Keck I telescope has been used to measure nine radial velocities having a median precision of ' 2 km s 1 for seven red giants belonging to the...
Galaxies: Where Space Becomes Time (2007)
UM Department of Astronomy, UM Student Astronomical Society, UM Exhibit Museum of Natural History, Michigan Center for Theoretical Physics
Mateo, Mario, Olszewski, Edward W., Walker, Matthew G.
(abridged) We present kinematic results for a sample of 387 stars located near Leo I based on spectra obtained with the MMT's Hectochelle spectrograph near the MgI/Mgb lines. We estimate the mean...
Velocity Dispersion Profiles of Seven Dwarf Spheroidal Galaxies (2007)
Walker, Matthew G., Mateo, Mario, Olszewski, Edward W., Gnedin, Oleg Y., Wang, Xiao, Sen, Bodhisattva, ...
We present stellar velocity dispersion profiles for seven Milky Way dwarf spheroidal (dSph) satellite galaxies. We have measured 8394 line-of-sight velocities (+/- 2.5 km/s) for 6804 stars from...
Walker, Matthew G., Mateo, Mario, Olszewski, Edward W., Bernstein, Rebecca, Sen, Bodhisattva, Woodroofe, Michael
We introduce a stellar velocity survey of dwarf spheroidal galaxies, undertaken using the Michigan/MIKE Fiber System (MMFS) at the Magellan/Clay 6.5 m telescope at Las Campanas Observatory. As of...
Piatek, Slawomir, Pryor, Carlton, Bristow, Paul, Olszewski, Edward W., Harris, Hugh C., Mateo, Mario, ...
The measured proper motion of Fornax, expressed in the equatorial coordinate system, is $(\mu_{\alpha},\mu_{\delta})=(47.6\pm 4.6,-36.0\pm 4.1)$ mas century$^{-1}$. This proper motion is a weighted...
Infrared photometry of Cepheids in the LMC clusters NGC 1866 and NGC 2031 (2006)
Testa, Vincenzo, Marconi, Marcella, Musella, Ilaria, Ripepi, Vincenzo, Dall'Ora, Massimo, Ferraro, Francesco R., ...
Near infrared (IR) studies of Cepheid variables in the LMC take advantage of the reduced light curve amplitude and metallicity dependence at these wavelengths. This work presents such photometry for...
On Kinematic Substructure in the Sextans Dwarf Spheroidal Galaxy (2006)
Walker, Matthew G., Mateo, Mario, Olszewski, Edward W., Pal, Jayanta Kumar, Sen, Bodhisattva, Woodroofe, Michael
We present multifiber echelle radial velocity results for 551 stars in the Sextans dwarf spheroidal galaxy and identify 294 stars as probable Sextans members. The projected velocity dispersion...
Internal Kinematics of the Fornax Dwarf Spheroidal Galaxy (2005)
Walker, Matthew G., Mateo, Mario, Olszewski, Edward W., Bernstein, Rebecca A., Wang, Xiao, Woodroofe, Michael
We present new radial velocity results for 176 stars in the Fornax dwarf spheroidal galaxy, of which at least 156 are probable Fornax members. We combine with previously published data to obtain a...
The Nature of the Density Clump in the Fornax Dwarf Spheroidal Galaxy (2005)
Olszewski, Edward W., Mateo, Mario, Harris, Jason, Walker, Matthew G., Coleman, Matthew G., Da Costa, G. S.
We have imaged the recently discovered stellar overdensity located approximately one core radius from the center of the Fornax dwarf spheroidal galaxy using the Magellan Clay 6.5m telescope with the...
Estimating Dark Matter Distributions (2005)
Wang, Xiao, Woodroofe, Michael, Walker, Matthew G., Mateo, Mario, Olszewski, Edward
Thanks to instrumental advances, new, very large kinematic datasets for nearby dwarf spheroidal (dSph) galaxies are on the horizon. A key aim of these datasets is to help determine the distribution...
Deep Hubble Space Telescope Imaging of IC 1613 II. The Star Formation History (2003)
Skillman, Evan D., Tolstoy, Eline, Cole, Andrew A., Dolphin, Andrew E., Saha, Abhijit, Gallagher, J. S., ...
We present deep HST WFPC2 imaging of the Local Group dwarf irregular galaxy IC 1613. The photometry is the deepest to date for an isolated dwarf irregular galaxy. The resulting color-magnitude...
Deep HST Imaging of Sextans A. III. The Star Formation History (2003)
Dolphin, Andrew E., Saha, A., Skillman, Evan D., Dohm-Palmer, R. C., Tolstoy, Eline, Cole, A. A., ...
We present a measurement of the star formation history of Sextans A, based on WFPC2 photometry that is 50% complete to V=27.5 (M_V ~+ 1.9) and I=27.0. The star formation history and chemical...
Deep HST Imaging of Sextans A. II. Cepheids and Distance (2002)
Dolphin, Andrew E., Saha, A., Skillman, Evan D., Dohm-Palmer, R. C., Tolstoy, Eline, Cole, A. A., ...
We have identified 82 short-period variable stars in Sextans A from deep WFPC2 observations. All of the periodic variables appear to be short-period Cepheids, with periods as small as 0.8 days for...
Von Braun, Kaspar, Mateo, Mario, Chiboucas, Kristin, Athey, Alex, Hurley-Keller, Denise
We report on photometry results of the equatorial globular clusters (GCs) M10 and M12. These two clusters are part of our sample of GCs which we are probing for the existence of photometrically...
Variable Stars in the Field of the Globular Cluster NGC 3201 (2001)
Von Braun, Kaspar, Mateo, Mario
We report on the discovery and analysis of 14 short-period variable stars in the field of the southern globular cluster NGC 3201, located within roughly two magnitudes on either side of the...
Radial Velocity of the Phoenix Dwarf Galaxy: Linking Gas and Hi Gas (2001)
Gallart, C., Martinez-Delgado, D., Gomez-Flechoso, M. A., Mateo, Mario
We present the first radial velocity measurement of the stellar component of the Local Group dwarf galaxy Phoenix, using FORS1 at the VLT UT1 (ANTU) telescope. From the spectra of 31 RGB stars, we...
Mapping the Galactic Halo III. Simulated Observations of Tidal Streams (2000)
Harding, Paul, Morrison, Heather L., Olszewski, Edward W., Arabadjis, John, Mateo, Mario, Dohm-Palmer, R. C., ...
We have simulated the evolution of tidal debris in the Galactic halo in order to guide our ongoing survey to determine the fraction of halo mass accreted via satellite infall. Contrary to naive...
Deep HST Imaging of IC 1613. I. Variable Stars and Distance (2000)
Dolphin, Andrew E., Saha, A., Skillman, Evan D., Tolstoy, Eline, Cole, A. A., Dohm-Palmer, R. C., ...
We present WFPC2 VI photometry of a field in the halo of IC 1613, finding 13 RR Lyraes and 11 Cepheids. Our photometry of the red giant branch tip and red clump is used to derive distances to IC...
An Extinction Map and Color Magnitude Diagram for the Globular Cluster NGC 3201 (2000)
Von Braun, Kaspar, Mateo, Mario
Differential $E_{V-I}$ variations of up to $\sim 0.2$ mag on a scale of arcminutes across NGC 3201 are presented in the form of an extinction map. This map, created by calculating average $E_{V-I}$...
Mapping the Galactic Halo II: Photometric Survey (2000)
Dohm-Palmer, R. C., Mateo, Mario, Olszewski, E., Morrison, H., Harding, Paul, Freeman, Kenneth C., ...
We present imaging results from a high Galactic latitude survey designed to examine the structure of the Galactic halo. The objective of the survey is to identify candidate halo stars which can be...
Mapping the Galactic Halo I. The `Spaghetti' Survey (2000)
Morrison, Heather L., Mateo, Mario, Olszewski, Edward W., Harding, Paul, Dohm-Palmer, R. C., Freeman, Kenneth C., ...
We describe a major survey of the Milky Way halo designed to test for kinematic substructure caused by destruction of accreted satellites. We use the Washington photometric system to identify halo...
Internal Kinematics of the Andromeda II Dwarf Spheroidal Galaxy (1999)
Cote, Patrick, Mateo, Mario, Olszewski, Edward, Cook, Kem
The High Resolution Echelle Spectrometer on the Keck I telescope has been used to measure nine radial velocities having a median precision of 2 km/s for seven red giants belonging to the isolated...
HST Studies of the WLM Galaxy. I. The Age and Metallicity of the Globular Cluster (1999)
Hodge, Paul W., Dolphin, Andrew E., Smith, Toby R., Mateo, Mario
We have obtained V and I images of the lone globular cluster that belongs to the dwarf Local Group irregular galaxy known as WLM. The color-magnitude diagram of the cluster shows that it is a normal...
Piatek, Slawomir, Pryor, Carlton, Bristow, Paul, Olszewski, Edward W., Harris, Hugh C., Mateo, Mario, ...
This article presents a measurement of the proper motion of the Ursa Minor dwarf spheroidal galaxy determined from images taken with the Hubble Space Telescope in two distinct fields. Each field...
Dwarf Galaxies of the Local Group (1998)
The Local Group (LG) dwarf galaxies offer a unique window to the detailed properties of the most common type of galaxy in the Universe. In this review, I update the census of LG dwarfs based on the...
Mateo, Mario, Olszewski, Edward W., Morrison, Heather L.
We have obtained deep photometric data in 24 fields along the southeast extension of the major axis of the Sagittarius dwarf spheroidal (Sgr dSph) galaxy, and in four fields along the northwest...
Mateo, Mario, Olszewski, Edward W., Vogt, Steven S., Keane, Michael J.
We present radial velocities of 33 red giants in the Leo I dSph galaxy obtained from spectra taken with the HIRES echelle spectrograph on the Keck I telescope. These data have a mean precision of 2.2...
Dwarf Cepheids in the Carina Dwarf Spheroidal Galaxy (1998)
Mateo, Mario, Hurley-Keller, Denise, Nemec, James
We have discovered 20 dwarf Cepheids (DC) in the Carina dSph galaxy from the analysis of individual CCD images obtained for a deep photometric study of the system. These short-period pulsating...
Detection of HI associated with the Sculptor Dwarf Spheroidal Galaxy (1998)
Carignan, Claude, Beaulieu, Sylvie, Cote, Stephanie, Demers, Serge, Mateo, Mario
Neutral hydrogen (HI) has been detected in the Local Group dwarf spheroidal galaxy Sculptor with the 64 m Parkes single dish and mapped with the Australia Telescope synthesis array. Most of the...
WFPC2 Observations of Leo A: A Predominantly Young Galaxy within the Local Group (1998)
Tolstoy, Eline, Gallagher, J. S., Cole, A. A., Hoessel, J. G., Saha, A., Dohm-Palmer, R. C., ...
The unprecedented detail of the WFPC2 colour-magnitude diagrams of the resolved stellar population of Leo A presented here allows us to determine a new distance and an accurate star formation history...
The Star Formation History of the Carina Dwarf Galaxy (1998)
Hurley-Keller, Denise, Mateo, Mario, Nemec, James
We have analyzed deep B and V photometry of the Carina dwarf spheroidal reaching below the old main-sequence turnoff to about V = 25. Using simulated color-magnitude diagrams to model a range of star...
Mass Segregation in Young LMC Clusters I. NGC 2157 (1997)
Fischer, Philippe, Pryor, Carlton, Murray, Stephen, Mateo, Mario, Richtler, Tom
We have carried out WFPC2 V- and I-band imaging of the young LMC cluster NGC 2157. Construction of a color-magnitude diagram and isochrone fitting yields an age of tau = 100 000 000 yrs, a reddening...
The Kinematics of Dwarf Spheroidal Galaxies (1997)
I review observational data on the kinematic properties of dwarf spheroidal galaxies in the halo of the Milky Way and beyond. The present data confirm previous claims that these galaxies have...
Mateo, Mario, Udalski, A., Szymanski, M., Kaluzny, J., Kubiak, M., Krzeminski, W.
We present deep CCD photometry of a field in the newly discovered dwarf spheroidal galaxy in Sagittarius (hereafter Sgr), and of a nearby control field. These data (totaling ~3.5 hrs exposure time in...
Dynamics of the Intermediate-Age Elliptical LMC Cluster NGC 1978 (1992)
Fischer, Philippe, Welch, Douglas L., Mateo, Mario
In this paper we investigate the internal dynamics of the LMC cluster NGC 1978 through the use of Photometric (CCD images) and kinematic (stellar radial velocities) data. We apply a variety of...