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Post Info TOPIC: Cepheus A
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Cepheus A East
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Title: Searching for the main powering outflow objects in Cepheus A East
Authors: Luis A. Zapata (CRyA-UNAM), Manuel Fernandez-Lopez (University of Illinois), Salvador Curiel (IA-UNAM), Nimesh Patel (CfA), Luis F. Rodriguez (CRyA-UNAM)

We present (sub)millimetre line and continuum observations in a mosaicing mode of the massive star forming region Cepheus A East made with the Submillimeter Array (SMA). Our mosaic covers a total area of about 3' x 12' centred in the HW 2/3 region. For the first time, this observational study encloses a high angular resolution (~ 3'') together with a large scale mapping of Cepheus A East. We report compact and high velocity ^{12}CO(2-1) emission associated with the multiple east-west bright H_2 condensations present in the region. Blueshifted and redshifted gas emission is found towards the east as well as west of HW 2/3. The observations suggest the presence of multiple large-scale east-west outflows that seems to be powered at smaller scales by radio sources associated with the young stars HW2, HW3c and HW3d. A kinematical study of part of the data suggests that the molecular outflow powered by HW2 is precessing with time as recently reported. Our data reveal five periodic ejections of material separated approximately every 10° as projected in the plane of the sky. The most recent ejections appear to move toward the plane of the sky. An energetic explosive event as the one that occurred in Orion BN/KL or DR21 does not explain the kinematics, and the dynamical times of the multiple ejections found here. The continuum observations only revealed a strong millimetre source associated with the HW 2/3 region. High angular resolution observations allow us to resolve this extended dusty object in only two compact sources (with spatial sizes of approximately 300 AU) associated with HW2 and HW3c. Finally, the bright optical/X-Ray HH 168 -- GDD37 object might be produced by strong shocks related with the outflow from HW3c.

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RE: Cepheus A
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Title: Water maser kinematics in massive star-forming regions: Cepheus A and W75N
Authors: J.M. Torrelles, N.A. Patel, S. Curiel, J.F. Gómez, G. Anglada, R. Estalella

VLBI multi-epoch water maser observations are a powerful tool to study the dense, warm shocked gas very close to massive protostars. The very high-angular resolution of these observations allow us to measure the proper motions of the masers in a few weeks, and together with the radial velocity, to determine their full kinematics. In this paper we present a summary of the main observational results obtained toward the massive star-forming regions of Cepheus A and W75N, among them: (i) the identification of different centers of high-mass star formation activity at scales of 100 AU; (ii) the discovery of new phenomena associated with the early stages of high-mass protostellar evolution (e.g., isotropic gas ejections); and (iii) the identification of the simultaneous presence of a wide-angle outflow and a highly collimated jet in the massive object Cep A HW2, similar to what is observed in some low-mass protostars. Some of the implications of these results in the study of high-mass star formation are discussed.

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Posts: 131433
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Title: The Chandra X-ray view of the power sources in Cepheus A
Authors: P. C. Schneider, H. M. Guenther, J. H. M. M. Schmitt

The central part of the massive star-forming region Cepheus A contains several radio sources which indicate multiple outflow phenomena, yet the driving sources of the individual outflows have not been identified. We present a high-resolution Chandra observation of this region that shows the presence of bright X-ray sources, consistent with active pre-main sequence stars, while the strong absorption hampers the detection of less luminous objects. A new source has been discovered located on the line connecting H_2 emission regions at the eastern and western parts of Cepheus A. This source could be the driving source of HH 168. We present a scenario relating the observed X-ray and radio emission.

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