Implications of stellar activity for exoplanetary atmospheres

2010 ◽  
Vol 9 (4) ◽  
pp. 239-243 ◽  
Author(s):  
P. Odert ◽  
M. Leitzinger ◽  
A. Hanslmeier ◽  
H. Lammer ◽  
M.L. Khodachenko ◽  
...  
Keyword(s):  
Extreme Ultraviolet ◽  
Planetary Atmospheres ◽  
Young Star ◽  
Young Stars ◽  
M Dwarfs ◽  
Low Mass Stars ◽  
X Ray ◽  
History Of ◽  
Low Mass ◽  
Exoplanetary Atmospheres

AbstractStellar X-ray and extreme ultraviolet (XUV) radiation is an important driver of the escape of planetary atmospheres. Young stars emit high XUV fluxes that decrease as they age. Since the XUV emission of a young star can be orders of magnitude higher compared to an older one, this evolution has to be taken into account when studying the mass-loss history of a planet. The temporal decrease of activity is closely related to the operating magnetic dynamo, which depends on rotation and convection in Sun-like stars. Using a sample of nearby M dwarfs, we study the relations between age, rotation and activity and discuss the influence on planets orbiting these low-mass stars.

scholarly journals A kinematically unbiased, all-sky search for nearby, young, low-mass stars

2019 ◽  
Vol 491 (1) ◽  
pp. 215-234 ◽  
Author(s):  
Alexander S Binks ◽  
Matthieu Chalifour ◽  
Joel H Kastner ◽  
David Rodriguez ◽  
Simon J Murphy ◽  
...  
Keyword(s):  
Young Star ◽  
Photometric Data ◽  
Young Stars ◽  
Stellar Clusters ◽  
Late Type ◽  
Low Mass Stars ◽  
Near Ir ◽  
Field Star ◽  
Low Mass ◽  
Moving Groups

ABSTRACT The past two decades have seen dramatic progress in our knowledge of the population of young stars of age $\lt \!200\,$ Myr that lie within $150\,$ pc of the Sun. These nearby, young stars, most of which are found in loose, comoving groups, provide the opportunity to explore (among many other things) the dissolution of stellar clusters and their diffusion into the field star population. Here, we exploit the combination of astrometric and photometric data from Gaia and photometric data from GALEX (UV) and 2MASS (near-IR) in an attempt to identify additional nearby, young, late-type stars. Specifically, we present a sample of 146 GALEX UV-selected late-type (predominantly K-type) field stars with Gaia-based distances $\lt \!125\,$ pc (based on Gaia Data Release 1) that have isochronal ages $\lt \!80\,$ Myr even if equal-components binaries. We investigate the spectroscopic and kinematic properties of this sample. Despite their young isochronal ages, only ∼10 per cent of stars among this sample can be confidently associated with established nearby, young moving groups (MGs). These candidate MG members include five stars newly identified in this study. The vast majority of our sample of 146 nearby young star candidates have anomalous kinematics relative to the known MGs. These stars may hence represent a previously unrecognized population of young stars that has recently mixed into the older field star population. We discuss the implications and caveats of such a hypothesis – including the intriguing fact that, in addition to their non-young-star-like kinematics, the majority of the UV-selected, isochronally young field stars within $50\,$ pc appear surprisingly X-ray faint.

scholarly journals X-ray Emission from Young Stars in Suburban Orion

2004 ◽  
Vol 219 ◽  
pp. 228-232
Author(s):  
K. Briggs ◽  
M. Güdel ◽  
M. Audard ◽  
K. Smith ◽  
R. Mewe ◽  
...  
Keyword(s):  
Main Sequence ◽  
Rotation Period ◽  
Magnetic Activity ◽  
Young Stars ◽  
Rossby Number ◽  
Low Mass Stars ◽  
X Ray ◽  
Star Forming ◽  
Low Mass ◽  
Pms Stars

X-ray emission from > 100 pre-main sequence (PMS) stars in the Orion star-forming complex is studied in a 20-ks observation by XMM-Newton. No relation between the ratio of X-ray and bolometric luminosities, LX/Lbol, and rotation period or Rossby number is exhibited, though the action of a solar-like dynamo is not excluded because all stars would appear to be in the “saturated regime” of such a dynamo. Low-mass stars showing a strong U — V excess have lower median X-ray luminosity, suggesting that accretion suppresses magnetic activity.

scholarly journals Constraining X-ray-Induced Photoevaporation of Protoplanetary Disks Orbiting Low-Mass Stars

2015 ◽  
Vol 10 (S314) ◽  
pp. 203-204
Author(s):  
Kristina M. Punzi ◽  
Joel H. Kastner ◽  
David Rodriguez ◽  
David A. Principe ◽  
Laura Vican
Keyword(s):  
Protoplanetary Disks ◽  
High Energy ◽  
Magnetic Activity ◽  
Young Star ◽  
Low Mass Stars ◽  
High Energy Radiation ◽  
X Ray ◽  
Radiation Fields ◽  
Low Mass ◽  
M Stars

AbstractLow-mass, pre-main sequence stars possess intense high-energy radiation fields as a result of their strong stellar magnetic activity. This stellar UV and X-ray radiation may have a profound impact on the lifetimes of protoplanetary disks. We aim to constrain the X-ray-induced photoevaporation rates of protoplanetary disks orbiting low-mass stars by analyzing serendipitous XMM-Newton and Chandra X-ray observations of candidate nearby (D < 100 pc), young (age < 100 Myr) M stars identified in the GALEX Nearby Young-Star Survey (GALNYSS).

scholarly journals Giant planets around AF and M stars

2013 ◽  
Vol 8 (S299) ◽  
pp. 64-65
Author(s):  
Julien Rameau ◽  
Gaël Chauvin ◽  
Anne-Marie Lagrange ◽  
Philippe Delorme ◽  
Justine Lannier
Keyword(s):  
Giant Planets ◽  
Early Type ◽  
Late Type ◽  
M Dwarfs ◽  
Low Mass Stars ◽  
Planetary Mass ◽  
Nearby Stars ◽  
Low Mass ◽  
M Stars ◽  
The One

AbstractWe present the results of two three-year surveys of young and nearby stars to search for wide orbit giant planets. On the one hand, we focus on early-type and massive, namely β Pictoris analogs. On the other hand, we observe late type and very low mass stars, i.e., M dwarfs. We report individual detections of new planetary mass objects. According to our deep detection performances, we derive the observed frequency of giant planets between these two classes of parent stars. We find frequency between 6 to 12% but we are not able to assess a/no correlation with the host-mass.

scholarly journals The young star cluster NGC 2362: low-mass population and initial mass function from a Chandra X-ray observation

2006 ◽  
Vol 460 (1) ◽  
pp. 133-144 ◽  
Author(s):  
F. Damiani ◽  
G. Micela ◽  
S. Sciortino ◽  
N. Huélamo ◽  
A. Moitinho ◽  
...  
Keyword(s):  
Mass Function ◽  
Young Star ◽  
Star Cluster ◽  
Initial Mass Function ◽  
Initial Mass ◽  
X Ray ◽  
Low Mass

scholarly journals Multi-Wavelength High-Resolution Spectroscopy for Exoplanet Detection: Motivation, Instrumentation and First Results

Geosciences ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 289 ◽  
Author(s):  
Serena Benatti
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Giant Planet ◽  
High Resolution Spectroscopy ◽  
M Dwarfs ◽  
Low Mass Stars ◽  
First Results ◽  
Multi Wavelength ◽  
Low Mass ◽  
Rocky Planets

Exoplanet research has shown an incessant growth since the first claim of a hot giant planet around a solar-like star in the mid-1990s. Today, the new facilities are working to spot the first habitable rocky planets around low-mass stars as a forerunner for the detection of the long-awaited Sun-Earth analog system. All the achievements in this field would not have been possible without the constant development of the technology and of new methods to detect more and more challenging planets. After the consolidation of a top-level instrumentation for high-resolution spectroscopy in the visible wavelength range, a huge effort is now dedicated to reaching the same precision and accuracy in the near-infrared. Actually, observations in this range present several advantages in the search for exoplanets around M dwarfs, known to be the most favorable targets to detect possible habitable planets. They are also characterized by intense stellar activity, which hampers planet detection, but its impact on the radial velocity modulation is mitigated in the infrared. Simultaneous observations in the visible and near-infrared ranges appear to be an even more powerful technique since they provide combined and complementary information, also useful for many other exoplanetary science cases.

scholarly journals The CARMENES search for exoplanets around M dwarfs

2018 ◽  
Vol 620 ◽  
pp. A171 ◽  
Author(s):  
R. Luque ◽  
G. Nowak ◽  
E. Pallé ◽  
D. Kossakowski ◽  
T. Trifonov ◽  
...  
Keyword(s):  
Bimodal Distribution ◽  
Photometric Data ◽  
M Dwarfs ◽  
Visual Channel ◽  
Low Mass Stars ◽  
Short Period ◽  
Low Mass ◽  
Periodic Signals ◽  
M Stars ◽  
Host Stars

We announce the discovery of two planetary companions orbiting around the low-mass stars Ross 1020 (GJ 3779, M4.0V) and LP 819-052 (GJ 1265, M4.5V). The discovery is based on the analysis of CARMENES radial velocity (RV) observations in the visual channel as part of its survey for exoplanets around M dwarfs. In the case of GJ 1265, CARMENES observations were complemented with publicly available Doppler measurements from HARPS. The datasets reveal two planetary companions, one for each star, that share very similar properties: minimum masses of 8.0 ± 0.5 M⊕ and 7.4 ± 0.5 M⊕ in low-eccentricity orbits with periods of 3.023 ± 0.001 d and 3.651 ± 0.001 d for GJ 3779 b and GJ 1265 b, respectively. The periodic signals around 3 d found in the RV data have no counterpart in any spectral activity indicator. Furthermore, we collected available photometric data for the two host stars, which confirm that the additional Doppler variations found at periods of approximately 95 d can be attributed to the rotation of the stars. The addition of these planets to a mass-period diagram of known planets around M dwarfs suggests a bimodal distribution with a lack of short-period low-mass planets in the range of 2–5 M⊕. It also indicates that super-Earths (>5 M⊕) currently detected by RV and transit techniques around M stars are usually found in systems dominated by a single planet.

scholarly journals X-Ray Detection of Brown Dwarfs with Chandra

2003 ◽  
Vol 211 ◽  
pp. 447-450 ◽  
Author(s):  
Scott J. Wolk
Keyword(s):  
Brown Dwarfs ◽  
Stellar Clusters ◽  
Brown Dwarf ◽  
Low Mass Stars ◽  
X Ray ◽  
Low Mass ◽  
Vast Range

I review recent observations of brown dwarfs by the Chandra X-ray Observatory. These observations fall in 2 categories, young stellar clusters which contain brown dwarfs and brown dwarf candidates and directed pointings at brown dwarfs and very low mass stars. Surprisingly, there are already over 60 published detections of brown dwarfs by Chandra. A review of the X–ray characteristics shows these objects are subject to flaring and their temperatures and luminosities have a vast range which is related to age.

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