AAVSO Alert Notice 427
Monitoring requested of the peculiar CV FS Aur
November 30, 2010
Monitoring requested of the peculiar cataclysmic variable FS Aur
Dr. Vitaly Neustroev (U. of Oulu, Finland) requests continuous, nightly monitoring of the cataclysmic variable FS Aurigae during the current (2010-2011) observing season to clearly define the start and end times of several consecutive dwarf nova outbursts and measure their outburst properties. FS Aurigae is a peculiar dwarf nova system exhibiting a number of periodicities and other phenomena whose origin is not yet understood. In addition to the strange periodicities present, the star also exhibits very short dwarf nova outbursts that have not been well-defined and covered fully throughout the cycle. The purpose of this campaign is to detect the next outburst of FS Aurigae as early as possible, and then to follow the outburst throughout its duration with intensive time-series observations. This will then be continued throughout the coming observing season.
Dr. Neustroev requests that observations be made at least twice on every clear night, and that all observations — both positive detections and negative “fainter-than” measurements — be reported as quickly as possible via the AAVSO’s WebObs data submission tool. It is critically important to detect and report the onset of the next outburst within a few hours; a number of observers spaced relatively evenly in longitude can accomplish this by adding this star to their nightly monitoring program, so intensive time-series observations are *not* required for the monitoring phase.
Upon detection and announcement of the outburst, observers are then encouraged to actively follow this star, and instrumental observers capable of conducting time-series photometry are encouraged to do so. Any filter (including clear) is acceptable for time-series, but V-filter observations are encouraged if possible. FS Aur typically varies between V=16 and 17 in quiescence, and outbursts typically reach V=13.5-14.0. For nightly monitoring, photometric errors of 0.1-0.2 magnitudes are acceptable, but observers capable of attaining better signal to noise in under 5-10 minutes are encouraged to do so. For observers making time-series measurements during outburst, please attempt to reach errors better than 0.05 magnitudes, preferably below 0.02. For observers making fainter-than estimates at all stages of the project, any observations that establish the star as fainter than V=14.5-15.0 are most useful. Instrumental observers are also asked to ensure that their computers are synchronized with a UTC time standard, so that time-series data from multiple observers may be correctly combined.
FS Aurigae is located at the following (J2000) coordinates:
RA: 05 47 48.32 , Dec: +28 35 11.6
Charts for FS Aurigae may be generated using AAVSO VSP: http://www.aavso.org/vsp
Please promptly submit all observations to the AAVSO using the name “FS AUR”. This campaign is referenced on the AAVSO Observing Campaigns webpage
(http://www.aavso.org/observing-campaigns).
This Alert Notice was prepared by Matthew R. Templeton.
Please use the following links:
Data submission: http://www.aavso.org/webobs
Alert Notice archive: http://www.aavso.org/alert-notice-archive
Subscription information: http://www.aavso.org/observation-notification#alertnotice
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Filed under: AAVSO Alerts
“In describing the measurements of CO2 at Mauna Loa Observatory: “The thin Pacific air is ideal for this research since it is “well-mixedâ€, meaning that there is no obvious nearby source of pollution, such as a heavy industry, or a natural “sinkâ€, such as forest which would absorb CO2.â€
No, except for the Pacific Ocean. I can understand why someone on Mauna Loa would overlook that.
“The oceans represent a significant sink for atmospheric carbon dioxide. Variability in the strength of this sink occurs on interannual timescales, as a result of regional and basin-scale changes in the physical and biological parameters that control the flux of this greenhouse gas into and out of the surface mixed layer. Here we analyse a 13-year time series of oceanic carbon dioxide measurements from station ALOHA in the subtropical North Pacific Ocean near Hawaii, and find a significant decrease in the strength of the carbon dioxide sink over the period 1989–2001. We show that much of this reduction in sink strength can be attributed to an increase in the partial pressure of surface ocean carbon dioxide caused by excess evaporation and the accompanying concentration of solutes in the water mass. Our results suggest that carbon dioxide uptake by ocean waters can be strongly influenced by changes in regional precipitation and evaporation patterns brought on by climate variability.”
From a 1994 article:
“The role of the ocean as a sink for anthropogenic carbon dioxide is a subject of intensive investigation and debate. Interest in this process is driven by the need to predict the rate of future increase of atmospheric carbon dioxide and subsequent global climatic change. Although estimates of the magnitude of the oceanic sink for carbon dioxide appear to be converging on a value of ∼2 (Gt) C yr−1 for the 1980s, a detailed understanding of the temporal and spatial variability in the rate of exchange of carbon dioxide between the ocean and the atmosphere is not available. For example, recent modeling work and direct measurements of air-sea carbon dioxide flux produce very different estimates of the air-sea flux in the northern hemisphere. As a consequence, it has been suggested that a large unidentified oceanic carbon dioxide sink may exist in the North Pacific. As a part of our time series observations in the North Pacific Subtropical Gyre, we have measured dissolved inorganic carbon and titration alkalinity over a four-year period. These measurements constitute the most extensive set of observations of carbon system parameters in the surface waters of the central Pacific Ocean. Our results show that the ocean in the vicinity of the time series site is a sink for atmospheric carbon dioxide. On the basis of these observations, we present a mechanism by which the North Pacific Subtropical Gyre can be a potential sink for ∼0.2 Gt C yr−1 of atmospheric carbon dioxide. Although our observations indicate that the North Pacific Subtropical Gyre is a sink for atmospheric carbon dioxide, the magnitude of this oceanic sink is relatively small. Our data and interpretations are therefore consistent with the argument for a relatively large sink during the 1980s in northern hemisphere terrestrial biomass. Another possibility is that the net release of carbon dioxide to the atmosphere owing to land use activities in tropical regions has been overestimated. ”
I take “interannual timescales” to be events over periods of more than a year, not seasonal changes. Perhaps that is wrong, but many conditions such as PDO are not seasonal and do affect CO2 sinks. Seems to me CO2 levels affected locally would not be reflected in measurements taken at different points on the globe for periods lasting over years.