The J-region asymptotic giant branch (JAGB) method is a new standard candle that is based on the stable intrinsic J-band magnitude of color-selected carbon stars, and has a precision comparable to other primary distance indicators such as Cepheids and the TRGB. We further test the accuracy of the JAGB method in the Local Group galaxy M33. M33's moderate inclination, low metallicity, and nearby proximity make it an ideal laboratory for tests of systematics in local distance indicators. Using high-precision optical BVI and near-infrared JHK photometry, we explore the application of three independent distance indicators: the JAGB method, the Cepheid Leavitt law, and the TRGB. We find: μ 0(TRGB I ) = 24.72 ± 0.02 (stat) ± 0.07 (sys) mag, μ 0(TRGBNIR) = 24.72 ± 0.04 (stat) ± 0.10 (sys) mag, μ 0(JAGB) = 24.67 ± 0.03 (stat) ± 0.04 (sys) mag, and μ 0(Cepheid) = 24.71 ± 0.04 (stat) ± 0.01 (sys) mag. For the first time, we also directly compare a JAGB distance using ground-based and space-based photometry. We measure μ 0(JAGBF110W) = 24.71 ± 0.06 (stat) ± 0.05 (sys) mag using the (F814W−F110W) color combination to effectively isolate the JAGB stars. In this paper, we measure a distance to M33 accurate to 2% and provide further evidence that the JAGB method is a powerful extragalactic distance indicator that can effectively probe a local measurement of the Hubble constant using spaced-based observations. We expect to measure the Hubble constant via the JAGB method in the near future, using observations from the James Webb Space Telescope.

The local determination of the Hubble constant sits at a crossroad. Current estimates of the local expansion rate of the universe differ by about 1.7σ, derived from the Cepheid- and TRGB-based calibrations, applied to Type Ia supernovae. To help elucidate possible sources of systematic error causing the tension, we show in this study the recently developed distance indicator, the J-region Asymptotic Giant Branch (JAGB) method, can serve as an independent cross-check and comparison with other local distance indicators. Furthermore, we make the case that the JAGB method has substantial potential as an independent, precise, and accurate calibrator of Type Ia supernovae for the determination of H 0. Using the Local Group galaxy Wolf–Lundmark–Melotte (WLM), we present distance comparisons between the JAGB method, a TRGB measurement at near-infrared (JHK) wavelengths, a TRGB measurement in the optical I band, and a multiwavelength Cepheid period–luminosity relation determination. We find μ 0 ( JAGB ) = 24.97 ± 0.02 ( stat ) ± 0.04 ( sys ) mag μ 0 ( TRGB NIR ) = 24.98 ± 0.04 ( stat ) ± 0.07 ( sys ) mag μ 0 ( TRGB F 814 W ) = 24.93 ± 0.02 ( stat ) ± 0.06 ( sys ) mag μ 0 ( Cepheids ) = 24.98 ± 0.03 ( stat ) ± 0.04 ( sys ) mag . All four methods are in good agreement, confirming the local self-consistency of the four distance scales at the 3% level and adding confidence that the JAGB method is as accurate and as precise a distance indicator as either of the other three astrophysically based methods.

Simpler and more rapid approaches for therapeutic drug-level monitoring are highly desirable to enable use at the point-of-care. We have developed an all-electronic approach for detection of the HIV drug tenofovir based on scalable fabrication of arrays of graphene field-effect transistors (GFETs) functionalized with a commercially available DNA aptamer. The shift in the Dirac voltage of the GFETs varied systematically with the concentration of tenofovir in deionized water, with a detection limit less than 1 ng/mL. Tests against a set of negative controls confirmed the specificity of the sensor response. This approach offers the potential for further development into a rapid and convenient point-of-care tool with clinically relevant performance.

We present an absolute calibration of the J-region Asymptotic Giant Branch (JAGB) method using published photometry of resolved stars in 20 nearby galaxies observed with the Hubble Space Telescope using the WFC3-IR camera and the F110W (broad J-band) filter. True distance moduli for each of the galaxies are based on the Tip of the Red Giant Branch (TRGB) method as uniformly determined by Dalcanton et al. From a composite color–magnitude diagram composed of over 6 million stars, leading to a sample of 453 JAGB stars in these galaxies, we find M F 110 W JAGB = − 5.77 ± 0.02 mag (statistical error on the mean). The external scatter seen in a comparison of the individual TRGB and the JAGB moduli is ±0.081 mag (or 4% in distance). Some of this scatter can be attributed to small number statistics arising from the sparse JAGB populations found in the generally low-luminosity galaxies that comprise the particular sample studied here. However, if this intermethod scatter is shared equitably between the JAGB and TRGB methods, that implies that each is good to ±0.06 mag, or better than 3% in distance.

Using parallaxes from Gaia Early Data Release 3 (EDR3), we determine multi-wavelength BVI c , JHK s , and [3.6] and [4.5] micron absolute magnitudes for 37 nearby Milky Way Cepheids, covering the period range between 5 and 60 days. We apply these period–luminosity relations to Cepheids in the Large and Small Magellanic Clouds and find that the derived distances are significantly discrepant with the geometric distances according to detached eclipsing binaries (DEBs). We explore several potential causes of these issues, including reddening, metallicity, and the existence of an additional zero-point offset, but none provide a sufficient reconciliation with both DEB distances. We conclude that the combination of the systematic uncertainties on the EDR3 parallaxes with the uncertainties on the effect of metallicity on the Cepheid distance scale leads to a systematic error floor of approximately 3%. We therefore find that the EDR3 data are not sufficiently accurate in the regime of these bright Cepheids to determine extragalactic distances precise to the 1% level at this time, in agreement with a number of contemporary studies.