Statistical Analysis of Water Masers in Star-forming Regions: Cepheus a and W75 N
نویسندگان
چکیده
We have done a statistical analysis of Very Long Baseline Array (VLBA) data of water masers in the star-forming regions (SFRs) Cepheus A and W75 N, using correlation functions to study the spatial clustering and Doppler-velocity distribution of these masers. Two-point spatial correlation functions show a characteristic scale size for clusters of water maser spots .1 AU, similar to the values found in other SFRs. This suggests that the scale for water maser excitation tends to be .1 AU. Velocity correlation functions show power-law dependences with indices that can be explained by regular velocity fields, such as expansion and/or rotation. These velocity fields are similar to those indicated by the water maser proper-motion measurements; therefore, the velocity correlation functions appear to reveal the organized motion of water maser spots on scales larger than 1 AU. Subject headings: ISM : individual (Cepheus A) — ISM : individual (W75 N) — ISM : jets and outflows — masers — methods : statistical
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