* Astronomy

Blobrana · L

RE: NN Serpentis

Blobrana · L

Title: The planets around NN Ser: still there
Author: T.R. Marsh, S.G. Parsons, M.C.P. Bours, S.P. Littlefair, C.M. Copperwheat, V.S. Dhillon, E. Breedt, C. Caceres, M.R. Schreiber

We present 25 new eclipse times of the white dwarf binary NN Ser taken with the high-speed camera ULTRACAM on the WHT and NTT, the RISE camera on the Liverpool Telescope, and HAWK-I on the VLT to test the two-planet model proposed to explain variations in its eclipse times measured over the last 25 years. The planetary model survives the test with flying colours, correctly predicting a progressive lag in eclipse times of 36 seconds that has set in since 2010 compared to the previous 8 years of precise times. Allowing both orbits to be eccentric, we find orbital periods of 7.9 ± 0.5 yr and 15.3 ± 0.3 yr, and masses of 2.3 ± 0.5 Jupiter masses and 7.3 ± 0.3 Jupiter masses. We also find dynamically long-lived orbits consistent with the data, associated with 2:1 and 5:2 period ratios. The data scatter by 0.07 seconds relative to the best-fit model, by some margin the most precise of any of the proposed eclipsing compact object planet hosts. Despite the high precision, degeneracy in the orbit fits prevents a significant measurement of a period change of the binary and of N-body effects. Finally, we point out a major flaw with a previous dynamical stability analysis of NN Ser, and by extension, with a number of analyses of similar systems.

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Blobrana · L

Title: The Planets around the Post-Common Envelope Binary NN Serpentis
Authors: F.V. Hessman, K. Beuermann, S. Dreizler, T.R. Marsh, S.G. Parsons, C.M. Copperwheat, D.E. Winget, G.F. Miller, J.J. Hermes, M.R. Schreiber, W. Kley, V.S. Dhillon, S.P. Littlefair

We have detected 2 circumbinary planets around the close binary system NN Serpentis using the orbital time delay effect measured via the sharp eclipses of the white dwarf primary. The present pre-cataclysmic binary was formed when the original - 2 M primary expanded into a red giant, causing the secondary star to drop from its original orbit at a separation of about 1.4 A.U. down to its current separation at 0.0043 A.U. A quasi-adiabatic evolution of the circumbinary planets' orbits during the common-envelope phase would have placed them in unstable configurations, suggesting that they may have suffered significant orbital drag effects and were originally in much larger orbits. Alternatively, they may have been created as 2nd-generation planets during the last million years from the substantial amount of material lost during the creation of the binary, making them the youngest planets known. Either solution shows how little we actually understand about planetary formation.

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UK Astronomers Help Find Snooker Star System

Astronomers at The University of Warwick and the University of Sheffield have helped discover an unusual star system which looks like, and may even once have behaved like, a game of snooker.
The University of Warwick and Sheffield astronomers played a key role in an international team that used two decades of observations from many telescopes around the world. The UK astronomers helped discover this "snooker like" star system through observations and analysis of data from an astronomical camera known as ULTRACAM designed by the British researchers on the team.
They looked at a binary star system called which is 1670 light years away from Earth. NN Serpentis is actually a binary star system consisting of two stars, a red dwarf and a white dwarf, which orbit each other in an incredibly close, tight orbit. By lucky chance Earth sits in the same plane as this binary star system, so we can we can see the larger red dwarf eclipse the white dwarf every 3 hours and 7 minutes.
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Blobrana · L

Scientists discover planets around elderly binary star

Scientists have discovered a planetary system consisting of at least two massive Jupiter-like planets orbiting the extremely close binary star system NN Serpentis.
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Blobrana · L

A nearby double-star owns two planets, astronomers report Friday, ones that may have survived some stellar ups-and-downs in their solar system.
In the current Astronomy & Astrophysics journal, a team led by Klaus Beuermann of Germany's Georg-August-Universität, reports that two Jupiter-sized planets circle the two stars in the NN Serpentis solar system, some 1,670 light years away (one light year is about 5.9 trillion miles.) The team re-analyzed light collected from the two stars from 1988 to 2010 to find signs of the two planets eclipsing the stars.
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University of Texas Students, Telescopes Help Discover Planets Around Elderly Binary Star

An international consortium of astronomers, including undergraduate and graduate students at The University of Texas at Austin, have discovered a planetary system consisting of at least two massive Jupiter-like planets orbiting the extremely close binary star system NN Serpentis. The team used a wide variety of observations taken over two decades from many telescopes, including two at The University of Texas at Austins McDonald Observatory in West Texas. The results are published online in the current edition of the journal Astronomy & Astrophysics.
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