scholarly journals The formation of bimodal dust species in nova ejecta – I. Chemical conditions

2019 ◽  
Vol 488 (1) ◽  
pp. 525-535 ◽  
Author(s):  
Chunhua Zhu ◽  
Helei Liu ◽  
Guoliang Lü ◽  
Zhaojun Wang ◽  
Lin Li
Keyword(s):  
Amorphous Carbon ◽  
White Dwarf ◽  
Accretion Rate ◽  
Carbon Number ◽  
Number Density ◽  
Chemical Profile ◽  
Chemical Abundances ◽  
Mixing Depth ◽  
Mass Accretion Rate ◽  
Chemical Conditions

Abstract It is still not known whether or not bimodal dust species (namely the silicate and amorphous carbon dust grains that are observed in a nova eruption) are formed in nova ejecta. Using the Modules for Experiments in Stellar Astrophysics code and considering the effects of the white dwarf mass, the mass-accretion rate and the chemical profile, which are described by a new parameter (the mixing depth), on the chemical abundances of nova ejecta, we investigate the possibility that bimodal dust species are produced in a nova eruption. We find that the C/O (the ratio of the carbon number density to the oxygen number density) of nova ejecta is affected by the mixing depth. For a model with a small mixing depth, the C/O of nova ejecta can evolve from greater than 1.0 to less than 1.0 over the course of an eruption, thereby providing the chemical conditions for the formation of bimodal dust species.

scholarly journals Rapid Mass Accretion in the Symbiotic Star AG Dra

1987 ◽  
Vol 93 ◽  
pp. 759-762
Author(s):  
T. Iijima
Keyword(s):  
White Dwarf ◽  
Accretion Rate ◽  
Symbiotic Star ◽  
Mass Accretion Rate ◽  
Accretion Process ◽  
Rapid Mass

AbstractThe mass accretion process onto the hot component of AG Dra and its explosive phenomena are discussed. The hot component seems to be a massive white dwarf (M > 1 M⊙). The mass accretion rate is estimated to be about 10−7M⊙/year. Many properties of the explosive phenomena agree with those of mild hydrogen flashes expected from this rapid mass accretion.

scholarly journals Discovery of an X-Ray Off-State in the Supersoft Source CAL 83

1997 ◽  
Vol 163 ◽  
pp. 730-731
Author(s):  
P. Kahabka
Keyword(s):  
White Dwarf ◽  
Accretion Rate ◽  
X Rays ◽  
X Ray ◽  
Mass Accretion Rate ◽  
Upper Limit ◽  
Linear Decline

AbstractAn X-ray off state of CAL 83 has been observed in April 1996 with the ROSAT HRI three weeks after a normal on state. An upper limit for a linear decline time of the observed flux of ~20 days (and of an efolding decline time of ~6 days) is deduced. This decline may be due to the response of the white dwarf envelope to a temporary increased mass accretion rate giving rise to an envelope expansion. CAL 83 may resemble the recurrent supersoft LMC transient RX J0513.9–6951 with episodes of disappearance in X-rays.

scholarly journals The relativistic mass accretion rate for accretion disk in the equatorial of rapidly rotating neutron stars

2021 ◽  
Vol 1869 (1) ◽  
pp. 012156
Author(s):  
A Yasrina ◽  
N Widianingrum ◽  
N S Risdianto ◽  
D Andra ◽  
N A Pramono ◽  
...  
Keyword(s):  
Neutron Stars ◽  
Accretion Disk ◽  
Accretion Rate ◽  
Mass Accretion Rate ◽  
Relativistic Mass

scholarly journals Searching for a link between the magnetic nature and other observed properties of Herbig Ae/Be stars

2008 ◽  
Vol 4 (S259) ◽  
pp. 395-396 ◽  
Author(s):  
Swetlana Hubrig ◽  
C. Grady ◽  
M. Schöller ◽  
O. Schütz ◽  
B. Stelzer ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Survey ◽  
Accretion Rate ◽  
Be Stars ◽  
General Correlation ◽  
X Ray ◽  
Mass Accretion Rate ◽  
Debris Disk ◽  
Magnetic Nature

AbstractWe present the results of a new magnetic field survey of Herbig Ae/Be and A debris disk stars. They are used to determine whether magnetic field properties in these stars are correlated with the mass-accretion rate, disk inclinations, companion(s), Silicates, PAHs, or show a more general correlation with age and X-ray emission as expected for the decay of a remnant dynamo.

scholarly journals H2O maser emission from the Seyfert 2 galaxy IC 2560: evidence for a super-massive black hole and a probe for mass-accretion rate

2002 ◽  
Vol 206 ◽  
pp. 400-403
Author(s):  
Yuko Ishihara ◽  
Naomasa Nakai ◽  
Naoko Iyomoto ◽  
Kazuo Makishima ◽  
Phil Diamond ◽  
...  
Keyword(s):  
Black Hole ◽  
High Velocity ◽  
Accretion Rate ◽  
Rotating Disk ◽  
Massive Black Hole ◽  
Central Mass ◽  
Maser Emission ◽  
Mass Accretion Rate ◽  
Systemic Velocity ◽  
Velocity Drift

Our observations of H2O masers have detected some high-velocity features and a secular velocity drift of the systemic features in the Seyfert 2 Galaxy IC 2560. The high-velocity features were blue- and red-shifted from the systemic velocity of 220-420 km s−1 and 210-350 km s−1, respectively. The velocity of the systemic features drifted at a secular rate of 2.62 km s−1 yr−1. Assuming the existence of a compact rotating disk as in NGC 4258, IC 2560 possesses a nuclear disk with inner and outer radii of 0.07 pc and 0.26 pc, respectively, and a confined mass of 2.8 × 106M⊙ at the center, making the central density > 2.1 × 109M⊙ pc−3. Such a dense object cannot be a cluster of stars, and this strongly suggests that the central mass is a super-massive black hole. Since the 2-10 keV luminosity of IC 2560 is 1 × 1041 erg s−1, the mass accretion rate of the suggested black hole must be 2 × 10−5M⊙ yr−1.

scholarly journals THE MASS ACCRETION RATE OF GALAXY CLUSTERS: A MEASURABLE QUANTITY

2016 ◽  
Vol 818 (2) ◽  
pp. 188 ◽  
Author(s):  
C. De Boni ◽  
A. L. Serra ◽  
A. Diaferio ◽  
C. Giocoli ◽  
M. Baldi
Keyword(s):  
Galaxy Clusters ◽  
Accretion Rate ◽  
Measurable Quantity ◽  
Mass Accretion Rate

scholarly journals Brown dwarf jets: Investigating the universality of jet launching mechanisms at the lowest masses

2010 ◽  
Vol 6 (S275) ◽  
pp. 396-399
Author(s):  
Emma Teresa Whelan ◽  
Francesca Bacciotti ◽  
Tom Ray ◽  
Catherine Dougados
Keyword(s):  
Accretion Rate ◽  
T Tauri Stars ◽  
Brown Dwarf ◽  
Central Mass ◽  
Mass Accretion Rate ◽  
T Tauri ◽  
Mass Outflow ◽  
The Common ◽  
Protostellar Objects

AbstractRecently it has become apparent that proto-stellar-like outflow activity extends to the brown dwarf (BD) mass regime. While the presence of accretion appears to be the common ingredient in all objects known to drive jets fundamental questions remain unanswered. The more prominent being the exact mechanism by which jets are launched, and whether this mechanism remains universal among such a diversity of sources and scales. To address these questions we have been investigating outflow activity in a sample of protostellar objects that differ considerably in mass and mass accretion rate. Central to this is our study of brown dwarf jets. To date Classical T Tauri stars (CTTS) have offered us the best touchstone for decoding the launching mechanism. Here we shall summarise what is understood so far of BD jets and the important constraints observations can place on models. We will focus on the comparison between jets driven by objects with central mass <0.1M⊙ and those driven by CTTSs. In particular we wish to understand how the the ratio of the mass outflow to accretion rate compares to what has been measured for CTTSs.

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