# THE UPS AND DOWNS OF α CENTAURI

@article{Ayres2014THEUA,
title={THE UPS AND DOWNS OF $\alpha$ CENTAURI},
author={Thomas R. Ayres},
journal={The Astronomical Journal},
year={2014},
volume={147}
}
• T. Ayres
• Published 4 January 2014
• Physics
• The Astronomical Journal
The following is a progress report on the long-term coronal (T ∼ 1 MK) activity of α Centauri A (HD 128620: G2 V) and B (HD 128621: K1 V). Since 2005, Chandra X-Ray Observatory has carried out semiannual pointings on AB, mainly with the High Resolution Camera, but also on two occasions with the Low-Energy Transmission Grating Spectrometer, fully resolving the close pair in all cases. During 2008–2013, Chandra captured the rise, peak, and initial decline of B's coronal luminosity. Together with…

## Figures and Tables from this paper

### THE FAR-ULTRAVIOLET UPS AND DOWNS OF ALPHA CENTAURI

Four years (2010–2014) of semiannual pointings by the Hubble Space Telescope Imaging Spectrograph (STIS) on nearby Alpha Centauri have yielded a detailed time history of far-ultraviolet (FUV:

### Serendipitous X-Ray Sources in the Chandra HRC Field around Alpha Centauri

• T. Ayres
• Physics
The Astronomical Journal
• 2018
For more than a decade, Alpha Centauri AB (G2 V+K1 V) has been observed by Chandra, in a long-term program to follow coronal (T ∼ 106 K) activity cycles of the two sunlike stars. Over 2008.4–2017.8,

### Optical, UV, and X-ray evidence for a 7-yr stellar cycle in Proxima Centauri

• Physics
• 2017
Stars of stellar type later than about M3.5 are believed to be fully convective and therefore unable to support magnetic dynamos like the one that produces the 11-year solar cycle. Because of their

### ALMA observations of α Centauri - First detection of main-sequence stars at 3 mm wavelength

• Physics
• 2015
Context. The precise mechanisms that provide the non-radiative energy for heating the chromosphere and the corona of the Sun and those of other stars constitute an active field of research. By

### Multi-wavelength variability of the young solar analog ι Horologii

• Physics
Astronomy & Astrophysics
• 2019
Context. Chromospheric activity cycles are common in late-type stars; however, only a handful of coronal activity cycles have been discovered. ι Hor is the most active and youngest star with known

### The radii and limb darkenings of α Centauri A and B . Interferometric measurements with VLTI/PIONIER

• Physics
• 2016
The photospheric radius is one of the fundamental parameters governing the radiative equilibrium of a star. We report new observations of the nearest solar-type stars α  Centauri A (G2V) and B (K1V)

### Detection of α Centauri at radio wavelengths: chromospheric emission and search for star–planet interaction

• Physics
Monthly Notices of the Royal Astronomical Society
• 2018
At radio wavelengths, solar type stars emit thermal free-free and gyroresonance, gyrosynchrotron, and impulsive coherent emission. Thermal free-free emission originates at layers where the optical

### A SEARCH FOR CORONAL ACTIVITY AMONG TWO METAL-POOR SUBDWARFS AND ONE SUBGIANT

• Physics
• 2016
A search has been made using the XMM-Newton satellite for coronal soft X-ray emission from HD 19445, HD 25329, and HD 140283, three Population II stars in the Galactic halo having metallicities of .

### Fifteen years in the high-energy life of the solar-type star HD 81809. XMM-Newton observations of a stellar activity cycle

• Physics
• 2017
Aims. The data set of the long-term XMM-Newton monitoring program of HD 81809 is analyzed to study its X-ray cycle, to investigate if the latter is related to the chromospheric one, to infer the

### Coronal X-ray emission and planetary irradiation in HD 209458

• Physics
• 2017
HD 209458 is one of the benchmark objects in the study of hot Jupiter atmospheres and their evaporation through planetary winds. The expansion of the planetary atmosphere is thought to be driven by

## References

SHOWING 1-10 OF 22 REFERENCES

### The Fainting of α Centauri A, Resolved

• Physics
• 2008
Beginning in 2003, XMM-Newton snapshot monitoring of α Centauri (HD 128620, 128621: G2 V, K1 V) documented a steady fading of the primary’s X-ray corona, which had all but disappeared by early 2005.

### THE CYCLES OF α CENTAURI

The main AB pair of the nearby α Centauri triple system has one of the most extensive X-ray records of any cosmic object, stretching over 30 years. The primary, α Cen A (G2 V), is a near twin of the

### X-rays from α Centauri – The darkening of the solar twin

• Physics
• 2005
We present first results from five XMM-Newton observations of the binary system α Centauri, which has been observed in snapshot like exposures of roughly two hours each during the last two years. In

### The Coronae of γ Draconis

• Physics
• 2006
The Chandra X-Ray Observatory has detected coronal (T ≳ 106 K) emission from the red giant γ Draconis (HD 164058: K5 III; d = 45 pc), now fully resolved from a stronger source 21'' to the SE that had

### Coronal activity cycles in nearby G and K stars - XMM-Newton monitoring of 61 Cygni and α Centauri

• Physics
• 2012
We use X-ray observations of the nearby binaries 61 Cyg A/B (K5V and K7V) and Alpha Cen A/B (G2V and K1V) to study the long-term evolution of magnetic activity in weakly to moderately active G + K

### X-RAY, FUV, AND UV OBSERVATIONS OF α CENTAURI B: DETERMINATION OF LONG-TERM MAGNETIC ACTIVITY CYCLE AND ROTATION PERIOD

• Physics, Geology
• 2010
Over the last couple of decades we have been carrying out a study of stellar magnetic activity, dynamos, atmospheric physics, and spectral irradiances from a sample of solar-type G0-5 V stars with

### Chandra-LETGS X-ray observation of α Centauri : A nearby (G2V + K1V) binary system

• Physics
• 2003
A Chandra LETGS X-ray observation of α Centauri with an exposure time of 81.5 ks is presented with the two components (K1V and G2V) spectrally resolved for the first time. We use the emission lines

### Establishing HZ43 A, Sirius B, and RX J185635-3754 as soft X-ray standards: a cross-calibration between the Chandra LETG+HRC-S, the EUVE spectrometer, and the ROSAT PSPC

• Physics
• 2006
Context. The absolute calibration of space-borne instruments in the soft X-ray regime rests strongly on model spectra of hot white dwarfs. Aims. We analyze the Chandra LETG+HRC observations of the

### The Structure of the Local Interstellar Medium. V. Electron Densities

• Physics
• 2008
We present a comprehensive survey of C II* absorption detections toward stars within 100 pc in order to measure the distribution of electron densities present in the local interstellar medium (LISM).

### Constraining the difference in convective blueshift between the components of alpha Centauri with precise radial velocities

• Physics
• 2002
New radial velocities of Cen A & B obtained in the framework the Anglo-Australian Planet Search programme as well as in the CORALIE programme are added to those by Endl et al. (2001) to improve the