Astrobites as a Community-led Model for Education, Science Communication, and Accessibility in Astrophysics

Support for early career astronomers who are just beginning to explore astronomy research is imperative to increase retention of diverse practitioners in the field. Since 2010, Astrobites has played an instrumental role in engaging members of the community -- particularly undergraduate and graduate students -- in research. In this white paper, the Astrobites collaboration outlines our multi-faceted online education platform that both eases the transition into astronomy research and promotes inclusive professional development opportunities. We additionally offer recommendations for how the astronomy community can reduce barriers to entry to astronomy research in the coming decade

Mira and Cepheid Variables as Extragalactic Distance Indicators in the Optical and the Near-Infrared

Local measurements of the Hubble constant rely on extragalactic distance measurements, which are made using observations of Type Ia supernovae and certain variable stars. This dissertation focuses on two classes of variable star that are used to make distance measurements: Classical Cepheids and Mira variables. The Legacy Survey of Space and Time (LSST), which will be conducted at the Vera C. Rubin Observatory, will return time-series data that have an ideal cadence for Mira studies. In anticipation of these data, we perform a search for Miras in the LSST photometric bands. We use archival optical and near-infrared observations of the galaxy M33 taken with the Canada-France-Hawaii Telescope’s MegaCam and WIRCam instruments. We use machine learning classifiers to efficiently identify strong Mira candidates, which are visually confirmed. We also use period-luminosity relations for Miras in the Large Magellanic Cloud to identify Mira candidates in M33. We present the first empirical characterization of Miras in the LSST bands. We also recover approximately 70 percent of a sample of previously identified Miras and identify 2,916 new Mira candidates. For the first time, we find evidence for a first-overtone pulsation sequence in M33’s Miras. We also present H-band Milky Way Cepheid light curves extracted via difference imaging from observations taken with the United Kingdom InfraRed Telecope’s Wide-Field Infrared Camera. The crowded nature of the Cepheid fields renders traditional photometric methods less effective, so we adapt and deploy a difference imaging pipeline originally written for data from the Transiting Exoplanet Survey Satellite. The light curves are used to derive corrections to “mean light” for random-phase Hubble Space Telescope observations. The phase corrections obtained from the H-band light curves are in good agreement with similar corrections obtained from VI light curves from the literature

A 1.3% distance to M33 from HST Cepheid photometry

International audienceWe present a low-dispersion period-luminosity relation (PL) based on 154 Cepheids in Messier 33 (M33) with Hubble Space Telescope (HST) photometry from the PHATTER survey. Using high-quality ground-based light curves, we recover Cepheid phases and amplitudes for multi-epoch HST data and we perform template fitting to derive intensity-averaged mean magnitudes. HST observations in the SH0ES near-infrared Wesenheit system significantly reduce the effect of crowding relative to ground-based data, as seen in the final PL scatter of $\sigma$ = 0.11 mag. We adopt the absolute calibration of the PL based on HST observations in the Large Magellanic Cloud (LMC) and a distance derived using late-type detached eclipsing binaries to obtain a distance modulus for M33 of $\mu$ = 24.622 $\pm$ 0.030 mag (d = 840 $\pm$ 11 kpc), a best-to-date precision of 1.3%. We find very good agreement with past Cepheid-based measurements. Several TRGB estimates bracket our result while disagreeing with each other. Finally, we show that the flux contribution from star clusters hosting Cepheids in M33 does not impact the distance measurement and we find only 3.7% of the sample is located in (or nearby) young clusters. M33 offers one of the best sites for the cross-calibration of many primary distance indicators. Thus, a precise independent geometric determination of its distance would provide a valuable new anchor to measure the Hubble constant

Astrobites as a Community-led Model for Education, Science Communication, and Accessibility in Astrophysics

Support for early career astronomers who are just beginning to explore astronomy research is imperative to increase retention of diverse practitioners in the field. Since 2010, Astrobites has played an instrumental role in engaging members of the community -- particularly undergraduate and graduate students -- in research. In this white paper, the Astrobites collaboration outlines our multi-faceted online education platform that both eases the transition into astronomy research and promotes inclusive professional development opportunities. We additionally offer recommendations for how the astronomy community can reduce barriers to entry to astronomy research in the coming decade

Astrobites as a Community-led Model for Education, Science Communication, and Accessibility in Astrophysics

Support for early career astronomers who are just beginning to explore astronomy research is imperative to increase retention of diverse practitioners in the field. Since 2010, Astrobites has played an instrumental role in engaging members of the community -- particularly undergraduate and graduate students -- in research. In this white paper, the Astrobites collaboration outlines our multi-faceted online education platform that both eases the transition into astronomy research and promotes inclusive professional development opportunities. We additionally offer recommendations for how the astronomy community can reduce barriers to entry to astronomy research in the coming decade