{"paper":{"title":"The Cepheid period -- luminosity -- metallicity relation based on Gaia DR2 data","arxiv_id":"1808.05796","primary_cat":"astro-ph.SR","submitted_at":"2018-08-17T08:40:31+00:00","version_compiled":"v1"},"notice":"Every quoted sentence is the authors' text from the arXiv listing abstract. Labels and probabilities are the outputs of classifier-1.13.0 on the question bank abstract-p1-20260923, exactly as returned. No sentence in this record was written by a language model.","schema":"pith.compiled-record/v0","status":"compiled","abstract":{"source":"arXiv listing abstract v1","sentences":[{"i":0,"p":0.55,"id":"s0","own":true,"role":"method","text":"We use parallax data from the Gaia second data release (GDR2), combined with parallax data based on Hipparcos and HST data, to derive the period-luminosity-metallicity (PLZ) relation for Galactic classical cepheids (CCs) in the V,K, and Wesenheit WVK bands.","hedge":{"p":1.0,"label":"asserted"},"own_p":0.94,"main_claim_p":0.04,"quantitative":false,"quantitative_p":0.41,"role_probabilities":{"gap":0.0,"method":0.55,"result":0.0,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.45,"interpretation":0.0}},{"i":1,"p":0.99,"id":"s1","own":true,"role":"method","text":"An initial sample of 452 CCs are extracted from the literature with spectroscopically derived iron abundances.","hedge":{"p":1.0,"label":"asserted"},"own_p":0.64,"main_claim_p":0.02,"quantitative":true,"quantitative_p":0.98,"role_probabilities":{"gap":0.0,"method":0.99,"result":0.0,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.01,"interpretation":0.0}},{"i":2,"p":1.0,"id":"s2","own":false,"role":"method","text":"Reddening values, pulsation periods, and mean magnitudes are taken from the literature.","hedge":{"p":0.99,"label":"asserted"},"own_p":0.13,"main_claim_p":0.01,"quantitative":false,"quantitative_p":0.04,"role_probabilities":{"gap":0.0,"method":1.0,"result":0.0,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.0}},{"i":3,"p":0.86,"id":"s3","own":true,"role":"result","text":"Based on nine CCs with a goodness-of-fit (GOF) statistic <8 and with an accurate non-Gaia parallax, a parallax zero-point offset of -0.049 +- 0.018 mas is derived.","hedge":{"p":1.0,"label":"asserted"},"own_p":0.95,"main_claim_p":0.06,"quantitative":true,"quantitative_p":0.99,"role_probabilities":{"gap":0.0,"method":0.13,"result":0.86,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.01,"interpretation":0.0}},{"i":4,"p":0.79,"id":"s4","own":true,"role":"method","text":"Selecting a GOF statistic <8 removes about 40\\% of the sample most likely related due to binarity.","hedge":{"p":0.71,"label":"hedged_possibility"},"own_p":0.83,"main_claim_p":0.02,"quantitative":true,"quantitative_p":0.99,"role_probabilities":{"gap":0.0,"method":0.79,"result":0.11,"background":0.0,"limitation":0.01,"future_work":0.0,"contribution":0.01,"interpretation":0.08}},{"i":5,"p":1.0,"id":"s5","own":true,"role":"method","text":"Excluding first overtone and multi-mode cepheids and applying some other criteria reduces the sample to about 200 stars.","hedge":{"p":0.99,"label":"asserted"},"own_p":0.8,"main_claim_p":0.02,"quantitative":true,"quantitative_p":0.95,"role_probabilities":{"gap":0.0,"method":1.0,"result":0.0,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.0}},{"i":6,"p":0.91,"id":"s6","own":true,"role":"result","text":"The derived PL(Z) relations depend strongly on the parallax zero-point offset.","hedge":{"p":1.0,"label":"asserted"},"own_p":0.88,"main_claim_p":0.12,"quantitative":false,"quantitative_p":0.07,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.91,"background":0.0,"limitation":0.02,"future_work":0.0,"contribution":0.0,"interpretation":0.07}},{"i":7,"p":1.0,"id":"s7","own":true,"role":"result","text":"The slope of the PL relation is found to be different from the relations in the LMC at the 3 sigma level.","hedge":{"p":1.0,"label":"asserted"},"own_p":0.95,"main_claim_p":0.08,"quantitative":true,"quantitative_p":0.97,"role_probabilities":{"gap":0.0,"method":0.0,"result":1.0,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.0}},{"i":8,"p":0.95,"id":"s8","own":true,"role":"result","text":"Fixing the slope to the value found in the LMC leads to a distance modulus (DM) to the LMC of order 18.7 mag, larger than the canonical distance.","hedge":{"p":0.91,"label":"asserted"},"own_p":0.89,"main_claim_p":0.07,"quantitative":true,"quantitative_p":0.99,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.95,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.05}},{"i":9,"p":0.52,"id":"s9","own":false,"role":"interpretation","text":"The canonical DM of around 18.5 mag would require a parallax zero-point offset of order $-0.1$ mas.","hedge":{"p":0.63,"label":"hedged_possibility"},"own_p":0.48,"main_claim_p":0.08,"quantitative":true,"quantitative_p":0.98,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.47,"background":0.01,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.52}},{"i":10,"p":0.52,"id":"s10","own":true,"role":"result","text":"Given the strong correlation between zero point, period and metallicity dependence of the PL relation, and the parallax zero-point offset there is no evidence for a metallicity term in the PLZ relation.","hedge":{"p":0.91,"label":"asserted"},"own_p":0.88,"main_claim_p":0.72,"quantitative":false,"quantitative_p":0.15,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.52,"background":0.0,"limitation":0.0,"future_work":0.0,"contribution":0.0,"interpretation":0.48}},{"i":11,"p":0.45,"id":"s11","own":true,"role":"limitation","text":"The GDR2 release does not allow us to improve on the current distance scale based on CCs.","hedge":{"p":0.96,"label":"asserted"},"own_p":0.76,"main_claim_p":0.46,"quantitative":false,"quantitative_p":0.08,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.22,"background":0.0,"limitation":0.45,"future_work":0.0,"contribution":0.0,"interpretation":0.33}},{"i":12,"p":0.64,"id":"s12","own":true,"role":"result","text":"The value of and the uncertainty on the parallax zero-point offset leads to uncertainties of order 0.15 mag on the distance scale.","hedge":{"p":0.99,"label":"asserted"},"own_p":0.83,"main_claim_p":0.09,"quantitative":true,"quantitative_p":0.98,"role_probabilities":{"gap":0.0,"method":0.0,"result":0.64,"background":0.0,"limitation":0.3,"future_work":0.0,"contribution":0.0,"interpretation":0.06}},{"i":13,"p":0.81,"id":"s13","own":false,"role":"future_work","text":"The parallax zero-point offset will need to be known at a level of 3 microas or better to have a 0.01 mag or smaller effect on the zero point of the PL relation and the DM to the 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