Search Publications

Evidence of a long-term trend in total solar irradiance
DOI: 10.1051/0004-6361/200912318 Bibcode: 2009A&A...501L..27F

Fröhlich, C.

Aims: During the solar minimum of 2008, the value of total solar irradiance at 1 AU (TSI) was more than 0.2 Wm-2 lower than during the last minimum in 1996, indicating for the first time a directly observed long-term change. On the other hand, chromospheric indices and hence solar UV irradiance do not exhibit a similar change.
Metho…

2009 Astronomy and Astrophysics
SOHO 173
An X-ray view of 82 LINERs with Chandra and XMM-Newton data
DOI: 10.1051/0004-6361/200912288 Bibcode: 2009A&A...506.1107G

Guainazzi, M.; Jiménez-Bailón, E.; González-Martín, O. +2 more

We present the results of a homogeneous X-ray analysis for 82 nearby low-ionisation, narrow emission-line regions (LINERs) selected from the catalogue of Carrillo et al. (1999, Rev. Mex. Astron. Astrofis., 35, 187). All sources have available Chandra (68 sources) and/or XMM-Newton (55 sources) observations. This is the largest sample of LINERs wit…

2009 Astronomy and Astrophysics
XMM-Newton eHST 171
Binary planetary nebulae nuclei towards the Galactic bulge. II. A penchant for bipolarity and low-ionisation structures
DOI: 10.1051/0004-6361/200912176 Bibcode: 2009A&A...505..249M

Miszalski, B.; Moffat, A. F. J.; Parker, Q. A. +1 more

Considerable effort has been applied towards understanding the precise shaping mechanisms responsible for the diverse range of morphologies exhibited by planetary nebulae (PNe).

At least 10-20% of PNe have central stars (CSPN) with a close binary companion thought responsible for heavily shaping the ejected PN during common-envelope (CE) evol…

2009 Astronomy and Astrophysics
eHST 170
Characteristics of solar-like oscillations in red giants observed in the CoRoT exoplanet field
DOI: 10.1051/0004-6361/200911858 Bibcode: 2009A&A...506..465H

Baudin, F.; Hatzes, A. P.; Baglin, A. +6 more

Context: Observations during the first long run (~150 days) in the exo-planet field of CoRoT increase the number of G-K giant stars for which solar-like oscillations are observed by a factor of 100. This opens the possibility to study the characteristics of their oscillations in a statistical sense.
Aims: We aim to understand the statistical d…

2009 Astronomy and Astrophysics
CoRoT 169
High-precision density measurements in the solar corona. I. Analysis methods and results for Fe XII and Fe XIII
DOI: 10.1051/0004-6361:200810143 Bibcode: 2009A&A...495..587Y

Young, P. R.; Mariska, J. T.; Hara, H. +1 more

Aims: The EUV Imaging Spectrometer (EIS) instrument on board the Hinode satellite has access to some of the best coronal density diagnostics, and the high sensitivity of the instrument now allows electron number density, N_e, measurements to an unprecedented precision of up to ±5% in active regions. This paper gives a thorough overview of data ana…

2009 Astronomy and Astrophysics
Hinode 167
The bolometric luminosity of type 2 AGN from extinction-corrected [OIII]. No evidence of Eddington-limited sources
DOI: 10.1051/0004-6361/200912023 Bibcode: 2009A&A...504...73L

Perola, G. C.; Bianchi, S.; Barcons, X. +3 more

Context: There have been recent claims that a significant fraction of type 2 AGN accrete close to or even above the Eddington limit. In type 2 AGN, the bolometric luminosity (L_b) is generally inferred from the [OIII] emission line luminosity (L_OIII). The key issue in estimating the bolometric luminosity in these AGN, is therefore to know the bol…

2009 Astronomy and Astrophysics
XMM-Newton 166
Magnetic activity in the photosphere of CoRoT-Exo-2a. Active longitudes and short-term spot cycle in a young Sun-like star
DOI: 10.1051/0004-6361:200810591 Bibcode: 2009A&A...493..193L

Aigrain, S.; Alonso, R.; Auvergne, M. +18 more

Context: The space experiment CoRoT has recently detected transits by a hot Jupiter across the disc of an active G7V star (CoRoT-Exo-2a) that can be considered as a good proxy for the Sun at an age of approximately 0.5 Gyr.
Aims: We present a spot modelling of the optical variability of the star during 142 days of uninterrupted observations pe…

2009 Astronomy and Astrophysics
CoRoT 162
The zCOSMOS redshift survey: the role of environment and stellar mass in shaping the rise of the morphology-density relation from z ~ 1
DOI: 10.1051/0004-6361/200912213 Bibcode: 2009A&A...503..379T

Kneib, J. -P.; Maccagni, D.; Cimatti, A. +57 more

Context: For more than two decades we have known that galaxy morphological segregation is present in the Local Universe. It is important to see how this relation evolves with cosmic time.
Aims: To investigate how galaxy assembly took place with cosmic time, we explore the evolution of the morphology-density relation up to redshift z ~ 1 using …

2009 Astronomy and Astrophysics
eHST 159
Transit spectrophotometry of the exoplanet HD 189733b. I. Searching for water but finding haze with HST NICMOS
DOI: 10.1051/0004-6361/200912776 Bibcode: 2009A&A...505..891S

Vidal-Madjar, A.; Sing, D. K.; Ballester, G. E. +5 more

We present Hubble Space Telescope near-infrared transit photometry of the nearby hot-Jupiter HD 189733b. The observations were taken with the NICMOS instrument during five transits, with three transits executed with a narrowband filter at 1.87 µm and two performed with a narrowband filter at 1.66 µm. Our observing st…

2009 Astronomy and Astrophysics
eHST 151
Hot stars observed by XMM-Newton. I. The catalog and the properties of OB stars
DOI: 10.1051/0004-6361/200912659 Bibcode: 2009A&A...506.1055N

Nazé, Y.

Aims: Following the advent of increasingly sensitive X-ray observatories, deep observations of early-type stars became possible. However, the results for only a few objects or clusters have until now been reported and there has been no large survey comparable to that based upon the ROSAT All-Sky Survey (RASS).
Methods: A limited survey of X-ra…

2009 Astronomy and Astrophysics
XMM-Newton 140