This website uses cookies to ensure you have the best experience. Learn more

Short Period Oscillations In Super Soft Novae Essay

1280 words - 6 pages

The Super Soft Source (SSS) phase of novae is the last major
evolutionary phase during which the hottest layers closest to the
surface of the white dwarf can be observed until the hydrogen content
of the accreted material is consumed or ejected. The X-ray and UV
evolution of novae during their outbursts has been determined using
Swift monitoring observations. Deeper, continuous XMM-Newton and
Chandra observations have been taken, guided by the long-term
evolution determined by Swift. The time when bright SSS emission
becomes visible, the turn-on time of the SSS phase, depends on the
evolution of the nova ejecta. Accurate predictions are currently not
possible from evolutionary models, but ...view middle of the document...

2010).
Furthermore, most recently, a 54-s transient period was found
in Swift data of the nova V339Del (Beardmore et al. 2013) and
in an XMM-Newton observation (Ness et al. 2013b), both taken
during the SSS phase. Meanwhile, no 54-s periodic signal was
seen in a Chandra observation that was also taken during the
SSS phase (Nelson et al. 2013). A second Chandra observation
was taken on day 114, but data are not yet publicly available.
In addition to novae, a similar short period of ∼ 67 s has
been seen by Odendaal et al. (2014) in the prominent persistent
SSS Cal 83 which they interpret as the spin period of the white
dwarf. While this is close to the break-up period, they argue that
the white dwarf may be spun up by accretion disc torques.
Evidently, this type of short-period oscillations originates
from the surface of the white dwarf hosting nuclear burning as
it was only seen in white dwarfs emitting SSS spectra. It will be
of interest whether the 35-54 s periods in the novae are related
to the 67-s period in the persistent SSS Cal 83. If the origin is
not the spin period of the white dwarf, it might be related to the
interiors or the nuclear burning regions, and understanding these
processes might give a new diagnostic method to determine
fundamental parameters such as the mass of the underlying
white dwarf. It is therefore of interest to have as many systems
as possible with short-period oscillations in order to identify
those properties that drive them.

We have searched for short-period variations in all systems
containing bright SSS emission, focusing here on XMM-Newton
and Chandra observations while a similar project based on all
Swift XRT data will be presented by Beardmore et al. For those
systems with short-period oscillations, we study the evolution
of signal strength and peak period.
We first describe in brevity the general observation techniques
and the observations used in this article in Sect. 2. We
then describe the timing analysis in Sect. 3 and the results in
Sect. 4, where we dedicate an extra subsection to each system in
which short-term oscillations are present, closing with Sect. 4.6
in which we briefly describe those observations in which no periodic
signal was found. We discuss our results in Sect. 5 and
summarise our findings and conclusions in Sect. 6.

The large X-ray observatories XMM-Newton and Chandra
observe from highly elliptical orbits allowing long uninterrupted
observations up to 2 days. The instrumentation provides for
high resolution in time and energy using various combinations
of CCD detectors and dispersive gratings. For more details, we
refer to the corresponding instrument papers, e.g., Jansen et al.
(2001); Strüder...

Find Another Essay On Short-period oscillations in super-soft novae

Theories of Sleep: The Role of Slow-Wave Sleep in Memory Consolidation

3322 words - 14 pages consolidation is one of the ostensible functions of sleep. The active system consolidation hypothesis and the synaptic homeostasis hypothesis (SHY) are the two main hypotheses for this putative function of sleep. The active system consolidation model proposes that the repeated reactivation of newly encoded representations in the hippocampus during slow wave sleep (SWS) drives a transfer of memory traces from short-term store in the hippocampus to

Global Financing and Exchange Rate Mechanisms

1016 words - 4 pages careful track of their transactions and investments. We will define how hard and soft currency and how they apply to the global financing and exchange rate mechanisms.Hard currency is defined by Investopedia.com, "A currency, usually from a highly industrialized country, that is widely accepted around the world as a form of payment for goods and services. A hard currency is expected to remain relatively stable through a short period of time, and

Excellent study notes for all science topics in year 10

4226 words - 17 pages the pregnancy until about day 280 (measured from the beginning of the menstrual cycle) when the baby is born.· The pregnancy or gestation period lasts about 270 days.PubertyPuberty is the time when a child begins to become sexually mature. There are large changes in hormonal levels. At the beining of puberty, the pituitary gland in the brain releases hormones that travel through the bloodstream to the testes or ovaries and stimulate them

The factors which affect the time for one full oscillation of a pendulum

2045 words - 8 pages results as accurate as possible I will measure the period of 10 oscillations and only use one decimal place to allow for my reaction time.ResultsAngle (º) Time Taken (sec) for 10 oscillations90º 13*4 13*4 13*8 13*7 Average:13*645º 13*2 13*2 13*1 12*9 13*1Length: 0*3m, Mass: 20gMass (g) Time Taken (sec) for 10 oscillations400g 11*1 11*3 11*3 11*4 Average:11*3100g 11*6 11*1 11*0 11*2 11*2Length: 0*2cm, Angle: 45ºLength (cm) Time

Tuned mass damper

6576 words - 26 pages been revealed as base isolation structures tend to be vulnerable to long period ground motions due to resonances and tuned mass damper systems are less effective in short period range (De Iuliis et al., 2008:1). This fact leads to an equal important task of combining both techniques into a unique system. Investigation of the proposed system theoretically and practically proved to be superior to a single separate one. This paper provides a

Super Bowl: It Is Not Just a Game

1405 words - 6 pages experiencing a weak economy and people have been trying to save money, this year’s game was only seven-hundred people short of the all-time high attendance record of 103,985 people which was set in Super Bowl 14 in 1980 (“Super Bowl History”). Proving the Super Bowl is such an immense event, more people tuned into the game in 2004 than voted in the United States presidential election (John 261). Participating in the largest game of their life

Principles of Physics in Ultrasound

2554 words - 10 pages transmitting pulses of ultrasound and opening a receiver gate for a short period between pulses. The delay in the gate determines the maximum distance between the transducer and the reflecting surface. In the past 2 years, 3D ultrasound machines have been developed; they work on the same principle as ordinary ultrasound. The difference is that they take a number of scans by moving the probe over the body, or rotating a

MGT448 Global Finance Paper

998 words - 4 pages countries due to its unrealistic exchange rates. Some of the current soft currencies are the peso, the Baht, Zlotys and the Hong Kong dollar.According to Investopedia, hard currency is defined as "a currency, usually from a highly industrialized country, that is widely accepted around the world as a form of payment for goods and services. By its nature, hard currency is expected to remain relatively stable through a short period of time and to be

The cambrian period

1063 words - 4 pages The Cambrian Period marks an important point in the history of life on earth; it is the time when most of the major groups of animals first appear in the fossil record. This event is sometimes called the "Cambrian Explosion", because of the relatively short time over which this diversity of forms appears.A lot can happen in 40 million years, the approximate length of the Cambrian period. Animals showed dramatic change and diversity during this

Optimism vs. Pessimism in Pope's Essay on Man and Leapor's Essay on Woman

2105 words - 8 pages Woman. She opens and closes with her thesis that woman cannot win:   "WOMAN, a pleasing but short-lived flower, Too soft for business and too weak for power: A wife in bondage, or neglected maid; Despised, if ugly; if she's fair, betrayed. Lines 1-4 "Éwith ten thousand follies to her charge, Unhappy woman's but a slave at large." Lines 59-60   By beginning and ending on the same thought, she

Comparing the 1929 Market Crash and the Current Position in the Stock Market

1478 words - 6 pages Industrial Average (DJIA) at the beginning of every year as a measure, the economy has grown in a log-linear fashion since 1897. There have been two major oscillations in the DJIA. The first major oscillation began in the early 1920s. In the period from 1924 to 1929 the DJIA rose from 100 to 300, just prior to the crash of October 1929. During the 1930's and the Great Depression, the DJIA reached a low of 42. The second major oscillation was less

Similar Essays

Black Holes Essay

3674 words - 15 pages detect these oscillations, but that method also proved fruitless. X-ray novas are a special class of X-ray binaries where the system contains a late-type optical companion (a star near the end of its life) and a compact object, which can be either a neutron star or a black hole. Usually the spectrum of the companion in this type of system is very weak compared to that of the gas, but in X-ray novae the fraction of light from X-ray heating is

Reasons Of The Failure Of Tacoma Narrows Bridge

2621 words - 11 pages Thesis: In order to prevent the collapse of the Tacoma Narrows Bridge, all the static and dynamic strains should have been taken into account which would have involved proper consideration of effects of environmental conditions, building materials and design. I. Environmental conditions A. Effects and behavior of winds 1. Moderate winds, large oscillations 2. Wind effects on bridges 3. Transfer of wind 4. Vortices 5. Vortex

Reaching Reality Essay

978 words - 4 pages in the universe 30 super novae happen, and approximately 4000 new stars are born. In this very second somewhere in the world, right now, the sun is setting in one town, and people are going to sleep, into their dreams, escaping from reality. However, at this particular second the sun is also rising somewhere, in some town, in someplace out there on planet earth. People are rising reluctantly out of their warm beds, waking from their own dreams

Stellar Evolution Essay

1888 words - 8 pages known to be one of the most remarkable, but not completely understood phenomenae in the universe, the super novae. The star first takes the form of a red supergiant and causes a series of nuclear reactions causing the combination of its heavier elements, and therefore removing its reaction capability and then losing its ability to counteract gravity. What happens next is not clearly understood, but a super novae takes place in matters of a