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1. Astrometric Measurements of WDS 22267+4433 ES 1346 AC

   Johnson, A; Jenson, N; Sagehorn, J; Kozubal, J; Ruiz, D (July 2024, Journal of double star observations)

   Freed, R; Harshaw, R; Genet, Russell M (Ed.)

   The double star system WDS 22267+4433 ES 1346 AC was observed using the Las Cumbres Global Telescope Network (LCOGT) 0.4 meter telescope on October 19th, 2023. Upon observation, the position angle was 359.97° and the separation was 7.997″. This data was compared to historical data acquired from the Washington Double Star Catalog, the US Naval Observatory, and the Gaia Database. Because Gaia DR3 does not have parallax and proper motion values for the primary or secondary stars of this system, a comparison to the C component could not be made. 

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2. Double degenerate candidates in the open cluster NGC 6633

   https://doi.org/10.1017/S1743921320001040  

   Barnett, Joseph W.; Williams, Kurtis A. (October 2019, Proceedings of the International Astronomical Union)

   null (Ed.)

   Abstract The study of white dwarfs, the end stage of stellar evolution for more than 95% of stars, is critical to bettering our understanding of the late stages of the lives of low mass stars. In particular, the post main sequence evolution of binary star systems is complex, and the identification and analysis of double degenerate systems is a crucial step in constraining models of binary star systems. Binary white dwarfs in open star clusters are particularly useful because cluster parameters such as distance, metal content, and total system age are more tightly constrained than for field double degenerates. Here we use the precision astrometry from the Gaia Data Release 2 catalog to study two other white dwarfs which were identified as candidate double degenerates in the field of the open star cluster NGC 6633. One of the two objects, LAWDS 4, is found to have astrometric properties fully consistent with that of the cluster. In such a case, the object is significantly overluminous for a single white dwarf, strongly indicating binarity. The second candidate binary, LAWDS 7, appears to be inconsistent with cluster membership, though a more thorough analysis is necessary to properly quantify the probability. At present we are proceeding to model the photometric and spectroscopic data for both objects as if they were cluster member double degenerates. Results of this latter analysis are forthcoming. Our results will add crucial data to the study of binary star evolution in open star clusters. 

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3. Polynomial bounds for chromatic number. III. Excluding a double star

   https://doi.org/10.1002/jgt.22862  

   Scott, Alex; Seymour, Paul; Spirkl, Sophie (July 2022, Journal of Graph Theory)

   Abstract A “double star” is a tree with two internal vertices. It is known that the Gyárfás–Sumner conjecture holds for double stars, that is, for every double star , there is a function such that if does not contain as an induced subgraph then (where are the chromatic number and the clique number of ). Here we prove that can be chosen to be a polynomial. 

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4. New Observations of WDS 23516+0814

   Punter_Velez, A B; Rivera_De_Jesus, L M; Rolon_Moreno, M A; Reyes_Colon, C G; Pantoja_Pantoja, C A; Lebron_Santos, M E; Stierwalt, S; Storrie-Lombardi, L; Gomez, E; Hopkinson, A; et al (January 2024, Journal of double star observations)

   Freed, R; Harshaw, R; Genet, Russell M (Ed.)

   We report on our observations of the double star system WDS23516+0814 (CHE 506, HD 223638). We selected a double star system with a few historical observations to contribute to the determination of its possible orbit. 

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5. New Astrometric Measurements of WDS 18234-4819 B938

   Andrukhiv, V; Lys, S; Marcel, M C (July 2024, Journal of Double Star Observations)

   Freed, R; Harshaw, R; Genet, Russell M (Ed.)

   This research delves into the analysis of the WDS 18234-4819 B 938 double-star system situated within the Telescopium constellation. Utilizing our observations, data from the Gaia Data Release 3 mission, and historical records, new measurements of the position angle and separation were acquired. The results indicate a position angle of 342.6° and a separation of 8.39", showcasing an observable increase in comparison to historical data. Furthermore, an exploration of the parallax and proper motion values suggests disparate distances from Earth and a lack of gravitational binding between the stars. Consequently, the WDS 18234-4819 B 938 double-star system is classified as an optical double. To affirm this conclusion, we advocate for future studies to monitor dynamic changes in system parameters. 

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