scholarly journals A Transient Shock-Wave in the Shell of the Be Star HD 184279

1987 ◽  
Vol 92 ◽  
pp. 95-98
Author(s):  
D. Ballereau ◽  
J. Chauville

HD 184279 (V1294 Aql) has presented in the past an emission spectrum on the first terms of the Balmer series, and shell absorptions on the hydrogen and neutral helium lines. Their variations have been reported by Merrill (1952), Merrill and Lowen (1953) and Svolopoulos (1975). Ballereau and Hubert-Delplace (1982) evidenced long-term V/R variations with an amplitude of ∼100 km s-1. Short-term photometric variations are irregular (Tempesti and Patriarca, 1976), while long-term variations are correlated with radial velocity (RV) of shell lines (Horn et al., 1982). Ballereau and Chauville (in preparation) extended the spectroscopic observations until 1984 and confirmed the pseudo-periodic variations, the last half-period ranging over 3.4 years (April 1, 1980-August 1, 1983).

1991 ◽  
Vol 130 ◽  
pp. 386-388
Author(s):  
Artie P. Hatzes ◽  
William D. Cochran

AbstractAt McDonald Observatory we have been monitoring the relative radial velocities of a sample of K giants. The technique employed uses the telluric O2 lines near 6300 Å as a reference for measuring the stellar line shifts. We demonstrate that precisions of 10 m s−1 are possible with this technique. We present radial velocity data covering a 2 year time span for α Boo, α Tau, and β Gem. All of these stars show both long term variations (~ several hundred days) with a peak-to-peak amplitude of about 400 m s−1 and short term variations (~ few days) with a peak-to-peak amplitude of about 100 m s−1. The long term variations may be due to the rotational modulation of surface active regions whereas the short term variations may be indicative of pulsations.


1994 ◽  
Vol 162 ◽  
pp. 234-235
Author(s):  
J. Arsenijevic ◽  
S. Jankov ◽  
S. Krsljanin ◽  
A.M. Hubert ◽  
H. Hubert ◽  
...  

The bright Be star κ Dra (HD 109387, B5 III, v.sini=249 km/s) is one of the rare mid B type stars which have presented FeII emission lines during strong emission phases. Spectroscopic variations were previously reported by many authors over different time scales: years, days and hours. Juza et al. (1991) proposed that κ Dra was the primary component of a binary system with Porb. = 61.55 days. Short-term and long-term variations in the linear optical polarization were also reported by Arsenijevic et al. (1986). We have tried, with our extensive joint material, to search for correlation between long-term spectroscopic and polarimetric variations with the aim of obtaining information on the behaviour of the circumstellar envelope.


1987 ◽  
Vol 92 ◽  
pp. 93-94
Author(s):  
J. Chauville ◽  
M. Alvarez ◽  
J.P. Sareyan ◽  
L. Ballereau ◽  
R. Michel

11 Cam (HD 32343 = HR 1622) is a so-called “pole-on” Be star known for its long term variations, already noted by Merrill and Burwell (1943). Recent determinations of visual magnitude and spectral type are V = 5.222 and B2.5Ve (Rufener, 1981). The Balmer line profiles, especially Hα, have been frequently studied; Briot (1971), for instance, measured 40 and 4.9 Å equivalent widths for Hα and Hβ respectively; the Hα/Hβ peak to continuum ratio is 6.43/2.02 according to Gray and Marlborough (1974) who give v sin i = 131 km s-1, close to the value of 140 km s-1 adopted by Kogure (1968).


2000 ◽  
Vol 175 ◽  
pp. 260-263 ◽  
Author(s):  
M. Floquet ◽  
C. Neiner ◽  
A.M. Hubert ◽  
E. Janot-Pacheco ◽  
N.V. Leister

AbstractThe pole-on Be star υ Cyg (HD 202904) displayed with Hipparcos photometry a strong long-lived outburst between 1989 and 1993. High S/N spectroscopic observations were obtained in August-September 1998. The photospheric λ6678 line is strongly perturbed by variable outer V and R emission components and is itself highly variable.All the studied quantities (profiles, EW, radial velocity of the line centroid, V and R emission components, V/R ratio) are dominated by ν = 1.5 c/d frequency. The first harmonic (ν = 3.0 c/d) is also detected in the central part of the profile. In the nrp frame, this pair of frequencies corresponds to a low degree sectorial g-mode l = |m| = 2. Moreover mid-term variations are superimposed to short ones.


2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Dr. Kamlesh Kumar Shukla

FIIs are companies registered outside India. In the past four years there has been more than $41 trillion worth of FII funds invested in India. This has been one of the major reasons on the bull market witnessing unprecedented growth with the BSE Sensex rising 221% in absolute terms in this span. The present downfall of the market too is influenced as these FIIs are taking out some of their invested money. Though there is a lot of value in this market and fundamentally there is a lot of upside in it. For long-term value investors, there’s little because for worry but short term traders are adversely getting affected by the role of FIIs are playing at the present. Investors should not panic and should remain invested in sectors where underlying earnings growth has little to do with financial markets or global economy.


2021 ◽  
pp. 244-248
Author(s):  
Michael J. Rosenfeld

Gay rights and marriage equality have advanced so far in the U.S. in the past decade that it would be all too easy to assume that the struggle is over. The opponents of gay rights, however, remain powerful. Readers can take inspiration from how dramatically attitudes toward gay rights have liberalized in the past two decades and how transformative the liberalization of attitudes has been. We live in a world where political lies often seem to have the upper hand. It is worth remembering that despite the many short term advantages that lies can yield in politics, the truth has some long term advantages as well. The way the marriage equality movement prevailed should be a lesson to anyone who wants to make progressive social change.


1995 ◽  
Vol 155 ◽  
pp. 409-410 ◽  
Author(s):  
Karen R. Pollard ◽  
P. L. Cottrell

The RV Tauri stars are semiregular pulsating variables located in the brightest part of the Cepheid II instability strip. They have a characteristic light curve of alternating deep and shallow minima. A subset of the RV Tauri stars (the RVb subclass) exhibit long-term (500 to 2600 day) light and radial velocity variations. Although it is well established that the short-term variations are due to pulsations, the long-term behaviour is not well understood.BVRI photometry and high-resolution spectra of U Mon (the brightest member of the RVb subclass) were obtained at the Mt John University Observatory (MJUO) between 1990 Aug and 1994 May. The light and colour curves obtained clearly show the long-term variation in U Mon (Fig. 1(a) and (b)). The reddest colours occur slightly later than the long-term minimum in the light curve. The short-term light and colour variations are ‘damped’ at the long-term minimum.


2016 ◽  
Vol 13 (1) ◽  
Author(s):  
Dana P. Goldman ◽  
Darius N. Lakdawalla ◽  
James R. Baumgardner ◽  
Mark T. Linthicum

AbstractMedical innovation has generated significant gains in health over the past decades, but these advances have been accompanied by rapid growth in healthcare spending. Faced with a growing number of high-cost but high-impact innovations, some have argued to constrain prices for new therapies – especially through global caps on pharmaceutical spending and limits on prices for individual drugs. We show that applying this threshold to past innovations would have limited access to many highly valuable drugs such as statins and anti-retrovirals. We also argue that budget caps violate several important principles of health policy. First, budget caps treat healthcare spending as a consumption good, like going to a movie or buying a meal. However, healthcare spending should be viewed as an investment, whose benefits accrue over many years – much like spending on education. Second, budgetary cost is a poor indicator of value, thereby distorting coverage decisions. Third, affordability arguments often use a short-term horizon, thereby missing that long-term health is society’s ultimate goal. Fourth, assessments of benefit should incorporate not just the immediate clinical benefit to patients, but also long-term health improvements, cost savings, and increased productivity. Fifth, global budget caps arbitrarily anchor spending on the status quo, thereby setting too stringent a threshold for socially-desirable innovation. In sum, a solitary focus on short-term costs can be detrimental to population health in the long-run. When medical treatment decisions are properly viewed as investments, budget caps are not the answer; rather, we need to find mechanisms to encourage spending decisions based on long-term value. Only then can we generate health returns to societal investments, while also encouraging the new research and development necessary to extend the gains of recent decades.


1994 ◽  
Vol 12 (10/11) ◽  
pp. 1065-1070 ◽  
Author(s):  
V. Mussino ◽  
O. Borello Filisetti ◽  
M. Storini ◽  
H. Nevanlinna

Abstract. Monthly averages of the Helsinki Ak-values have been reduced to the equivalent aa-indices to extend the aa-data set back to 1844. A periodicity of about five cycles was found for the correlation coefficient (r) between geomagnetic indices and sunspot numbers for the ascending phases of sunspot cycles 9 to 22, confirming previous findings based on a minor number of sunspot cycles. The result is useful to researchers in topics related to solar-terrestrial physics, particularly for the interpretation of long-term trends in geomagnetic activity during the past, and to forecast geomagnetic activity levels in the future.


Author(s):  
Paul D. Miller

Afghanistan has twice been thrust front and center of US national security concerns in the past half-century: first, during the Soviet-Afghan War, when Afghanistan served as a proxy for American efforts to combat Soviet influence; and second, as the frontline state and host for America’s global response to al-Qaida’s terrorist attacks of 2001. In both instances, American involvement swung from intensive investment and engagement to withdrawal and neglect. In both cases, American involvement reflected US concerns more than Afghan realities. And both episodes resulted in short-term successes for American security with long-term consequences for Afghanistan and its people. The signing of a strategic partnership agreement between the two countries in 2012 and a bilateral security agreement in 2013 created the possibility of a steadier and more forward-looking relationship—albeit one that the American and Afghan people may be less inclined to pursue as America’s longest war continues to grind on.


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