* Astronomy

Blobrana · L

RE: SS Cygni

Blobrana · L

Astronomers team up with the public to solve decade old puzzle

An extremely precise measurement of the distance to a star system has finally allowed astronomers to solve a decade-old puzzle, confirming understanding of the way exotic objects like black holes interact with nearby stars.
Published today in prestigious journal Science, a team of astronomers headed by Dr James Miller-Jones from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), have measured the distance to star system SS Cygni to be 372 light years, much closer than a previous measurement made by the Hubble Space Telescope in the 1990s.
The measurement was made possible by amateur astronomers from the American Association of Variable Star Observers (AAVSO) who alerted the team to changes in the compact star system, triggering the team to start observations with two of the world's most accurate radio telescopes.
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Blobrana · L

Accurate Distance Measurement Resolves Major Astronomical Mystery

Sometimes astronomy is like real estate -- what's important is location, location, and location. Astronomers have resolved a major problem in their understanding of a class of stars that undergo regular outbursts by accurately measuring the distance to a famous example of the type.
The researchers used the National Science Foundation's Very Long Baseline Array (VLBA) and the European VLBI Network (EVN) to precisely locate one of the most-observed variable-star systems in the sky -- a double-star system called SS Cygni -- at 370 light-years from Earth. This new distance measurement meant that an explanation for the system's regular outbursts that applies to similar pairs also applies to SS Cygni.
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Blobrana · L

Title: Fitting the Chandra LETG spectrum of SS Cygni in outburst with model atmosphere spectra
Authors: V.F. Suleimanov (1,2), C.W. Mauche (3), R.Ya. Zhuchkov (2), K. Werner (1), ((1) Institute for Astronomy and Astrophysics, Kepler Center for Astro and Particle Physics, Eberhard Karls University, Tübingen, Germany, (2) Kazan Federal University, Russia, (3) Lawrence Livermore National Laboratory, USA)

The Chandra / LETG spectrum of SS Cyg in outburst shows broad (\approx 5 A) spectral features that have been interpreted as a large number of absorption lines on a blackbody continuum with a temperature of 250 kK (Mauche 2004). It is most probable that this is the spectrum of the fast-rotating optically thick boundary layer on the white dwarf surface. Here we present the results of fitting this spectrum with high gravity hot stellar model atmospheres. An extended set of LTE model atmospheres with solar chemical composition was computed for this purpose. The best fit is obtained with the following parameters: T_eff=190 kK, log g=6.2, and N_H=8 10^{19} cm^{-2}. The spectrum of this model describes the observed spectrum in the 60--125 A range reasonably well, but at shorter wavelengths the observed spectrum has much higher flux. The reasons for this are discussed. The derived low surface gravity supports the hypothesis of the fast rotating boundary layer.

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Blobrana · L

The cataclysmic variable star SS Cygni is in outburst.

Date of Outburst: 22nd March, 2012
Magnitude: 7.7 - 12.4 V
Period: 49.5 days (?)
Satellite Period: 0.2751300 days
Type: UGSS

Position(2000): RA=21 42 42.79 | Dec=+43° 35' 09.9"

Blobrana · L

The cataclysmic variable star SS Cygni is in outburst.

Date of Outburst: 24th January, 2012
Magnitude: 7.7 - 12.4 V
Period: 49.5 days (?)
Satellite Period: 0.2751300 days
Type: UGSS

Position(2000): RA=21 42 42.79 | Dec=+43° 35' 09.9"

Blobrana · L

The cataclysmic variable star SS Cygni is in outburst.

Date of Outburst: 30th October, 2011
Magnitude: 7.7 - 12.4 V
Period: 49.5 days (?)
Satellite Period: 0.2751300 days
Type: UGSS

Position(2000): RA=21 42 42.79 | Dec=+43° 35' 09.9"

Blobrana · L

The cataclysmic variable star SS Cygni is in outburst.

Date of Outburst: 24th August, 2011
Magnitude: 7.7 - 12.4 V
Period: 49.5 days
Satellite Period: 0.27513 days
Type: UGSS

Position(2000): RA=21 42 42.79 | Dec=+43° 35' 09.9"

Blobrana · L

The easiest way to find SS Cygni is to start at Rho Cygni, a 4th magnitude star often visible from places with moderate light pollution, particularly when Cygnus is high (late summer and fall evenings are good from the United States and other mid-northern-latitude locations):
Once you've found Rho, it's a fairly simple star hop to SS Cygni. There's a very conspicuous pattern of 8th and 9th magnitude stars near Rho that looks a little like an oddly bent hockey stick. You should be able to follow the "stick" in your finder from all but the most light-polluted sites.
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AAVSO "b" scale (3° wide; finder or very low power)

AAVSO "d" scale (1° wide; low-to-medium power in small scopes)

Blobrana · L

The cataclysmic variable star SS Cygni is in outburst.

Date of Outburst: 26th June, 2011
Magnitude: 7.7 - 12.4 V
Period: 49.5 days
Satellite Period: 0.27513 days
Type: UGSS

Position(2000): RA=21 42 42.79 | Dec=+43°35'09.9"