A reevaluation of the 2MASS zero points using CALSPEC spectrophotometry complemented with <i>Gaia</i> Data Release 2 parallaxes

Apellániz, J. Maíz; González, M. Pantaleoni

doi:10.1051/0004-6361/201833918

Cited by 18 publications

(8 citation statements)

References 19 publications

(16 reference statements)

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“…Second, the uncertainties in J, H, and K are independent but those of J − H and H − K are anticorrelated, see the ellipses in Fig. 2 of Maíz Apellániz & Pantaleoni González (2018) 2 . Third, objects near the edges (mostly the left one) are moved in and out of the plot by the application of the procedures (edge diffusion).…”

Section: Extinction Treatmentmentioning

confidence: 99%

“…To compare the observed data with synthetic photometry we use the 2MASS bandpasses of Skrutskie et al (2006) and the zero points of Maíz Apellániz & Pantaleoni González (2018). For the stellar models we use the Milky Way metallicity T eff -luminosity class grid of Maíz Apellániz (2013b).…”

Section: Calibration and Modelsmentioning

confidence: 99%

“…In that respect, a 4.75 kK giant is at the red clump location while a 4 kK giant is halfway up the red giant branch, so the second has a significantly higher luminosity and lower gravity. thetic photometry calculated with the code created for CHORIZOS (Maíz Apellániz 2004) using the 2MASS zero points of Maíz Apellániz & Pantaleoni González (2018). Keep in mind that some SEDfitting codes do not do this correctly, as they only extinguish fluxes at central wavelengths and in that way do not take into account non-linear photometric effects.…”

Section: Appendix A: Non-linear Photometric Effects Caused By Extinct...mentioning

confidence: 99%

“…And third, by properly dealing with the non-linear effects of extinction. We do not have to start from scratch, as we have previously developed tools for this purpose such as CHORIZOS (Maíz Apellániz 2004), studied the sensitivity curves and zero points of different photometric systems (Maíz Apellániz 2005, 2006, 2017Maíz Apellániz & Pantaleoni González 2018;Maíz Apellániz & Weiler 2018), derived a preliminary family of extinction laws (Maíz Apellániz et al 2014), analyzed the extinction of O stars in the solar neighborhood (Maíz Apellániz & Barbá 2018), created a spectral energy distribution (SED) model grid to compare with real data (Maíz Apellániz 2013b), and dealt with the associated non-linear photometric effects (references above plus Maíz Apellániz 2013a and the appendix here).…”

Section: Introductionmentioning

confidence: 99%

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Galactic extinction laws: I. A global NIR analysis with 2MASS photometry

Apellániz,

González,

Barbá

et al. 2020

Preprint

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We have started an ambitious program to determine if the full diversity of extinction laws is real or if some of it is due to calibration or methodological issues. Here we start by analyzing the information on NIR extinction in a 2MASS stellar sample with good quality photometry and very red colours. We calculate the extinction at 1 µm, A 1 , and the power-law exponent, α (A λ = A 1 λ −α ), for the 2MASS stars located in the extinction trajectory in the H − K vs. J − H plane expected for red giants with A 1 > 5 mag. We test the validity of the assumption about the nature of those stars, whether a single or multiple values of α are needed, and the spatial variations of the results. Most (∼83%) of those stars can indeed be explained by high-extinction red giants and the rest is composed of extinguished AGB stars (mostly O-rich), blended sources, and smaller numbers of other objects, a contaminant fraction that can be reduced with the help of Gaia DR2 data. Galactic red giants experience a NIR extinction with α ∼ 2.27 and an uncertainty of a few hundredths of a magnitude. There is no significant spread in α even though our sample is widely distributed and has a broad range of extinctions. Differences with previous results are ascribed to the treatment of non-linear photometric effects and/or the contaminant correction. Future research should concentrate in finding the correct functional form for the NIR extinction law. In the appendix we detail the treatment of non-linear photometric effects in the 2MASS bands.

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Section: Extinction Treatmentmentioning

confidence: 99%

Section: Calibration and Modelsmentioning

confidence: 99%

Section: Appendix A: Non-linear Photometric Effects Caused By Extinct...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Galactic extinction laws: I. A global NIR analysis with 2MASS photometry

Apellániz,

González,

Barbá

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…4 . The zero-points with their standard errors are taken from Maíz Apellániz & Pantaleoni González (2018). For the WISE photometry we calculate synthetic magnitudes on the AB magnitude scale and then apply the corrections to Vega magnitudes from Jarrett et al (2011) for which the estimated error is 1.45% (0.016 mag).…”

Section: Synthetic Photometrymentioning

confidence: 99%

Fundamental effective temperature measurements for eclipsing binary stars – I. Development of the method and application to AI Phoenicis

Miller

Maxted

Smalley

2020

Monthly Notices of the Royal Astronomical Society

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Stars with accurate and precise effective temperature (Teff) measurements are needed to test stellar atmosphere models and calibrate empirical methods to determine Teff. There are few standard stars currently available to calibrate temperature indicators for dwarf stars. Gaia parallaxes now make it possible, in principle, to measure Teff for many dwarf stars in eclipsing binaries. We aim to develop a method that uses high-precision measurements of detached eclipsing binary stars, Gaia parallaxes and multi-wavelength photometry to obtain accurate and precise fundamental effective temperatures that can be used to establish a set of benchmark stars. We select the well-studied binary AI Phoenicis to test our method, since it has very precise absolute parameters and extensive archival photometry. The method uses the stellar radii and parallax for stars in eclipsing binaries. We use a Bayesian approach to obtain the integrated bolometric fluxes for the two stars from observed magnitudes, colours and flux ratios. The fundamental effective temperature of two stars in AI Phoenicis are 6199 ± 22 K for the F7 V component and 5094 ± 16 K for the K0 IV component. The zero-point error in the flux scale leads to a systematic error of only 0.2% (≈ 11 K) in Teff. We find that these results are robust against the details of the analysis, such as the choice of model spectra. Our method can be applied to eclipsing binary stars with radius, parallax and photometric measurements across a range of wavelengths. Stars with fundamental effective temperatures determined with this method can be used as benchmarks in future surveys.

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Reanalysis of the Gaia Data Release 2 photometric sensitivity curves using HST/STIS spectrophotometry

Apellániz

Weiler

2018

A&A

Self Cite

172

117

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Context. The second data release (DR2) from the European Space Agency mission Gaia took place on April 2018. DR2 included photometry for more than 1.3 · 10 9 sources in the three bands G, G BP , and G RP . Even though the Gaia DR2 photometry is very precise, there are currently three alternative definitions of the sensitivity curves that show significative differences. Aims. The aim of this paper is to improve the quality of the input calibration data to produce new compatible definitions of the G, G BP , and G RP bands and to identify the reasons for the discrepancies between previous definitions. Methods. We have searched the HST archive for STIS spectra with G430L+G750L data obtained with wide apertures and combined them with the CALSPEC library to produce a high quality SED library of 122 stars with a broad range of colors, including three very red stars. This library defines new sensitivity curves for G, G BP , and G RP using a functional analytical formalism. Results. The new sensitivity curves are significantly better than the two previous attempts we use as a reference, REV and WEI. For G we confirm the existence of a systematic bias in magnitude and correct a color term present in REV. For G BP we confirm the need to define two magnitude ranges with different sensitivity curves and measure the cut between them at G phot = 10.87 mag with a significant increase in precision. The new curves also fit the data better than either REV or WEI. For G RP , our new sensitivity curve fits the STIS spectra better and the differences with previous attempts reside in a systematic effect between ground-based and HST spectral libraries. Additional evidence from color-color diagrams indicate that the new sensitivity curve is more accurate. Nevertheless, there is still room for improvement in the accuracy of the sensitivity curves because of the current dearth of good-quality red calibrators: adding more to the sample should be a priority before Gaia data release 3 takes place.

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A reevaluation of the 2MASS zero points using CALSPEC spectrophotometry complemented with Gaia Data Release 2 parallaxes

Cited by 18 publications

References 19 publications

Galactic extinction laws: I. A global NIR analysis with 2MASS photometry

Galactic extinction laws: I. A global NIR analysis with 2MASS photometry

Fundamental effective temperature measurements for eclipsing binary stars – I. Development of the method and application to AI Phoenicis

Reanalysis of the Gaia Data Release 2 photometric sensitivity curves using HST/STIS spectrophotometry

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