New limits on the surface density of M dwarfs. I - Photographic survey and preliminary CCD data

1985 ◽  
Vol 90 ◽  
pp. 817 ◽  
Author(s):  
P. C. Boeshaar ◽  
J. A. Tyson
Keyword(s):  
Surface Density ◽  
M Dwarfs ◽  
Photographic Survey

scholarly journals Ejection of close-in super-Earths around low-mass stars in the giant impact stage

2020 ◽  
Vol 642 ◽  
pp. A23
Author(s):  
Yuji Matsumoto ◽  
Pin-Gao Gu ◽  
Eiichiro Kokubo ◽  
Shoichi Oshino ◽  
Masashi Omiya
Keyword(s):  
Surface Density ◽  
Dynamical Evolution ◽  
Central Star ◽  
Stellar Mass ◽  
Mass Relation ◽  
M Dwarfs ◽  
Low Mass Stars ◽  
Giant Impact ◽  
Low Mass ◽  
Strong Scattering

Context. Earth-sized planets were observed in close-in orbits around M dwarfs. While more and more planets are expected to be uncovered around M dwarfs, theories of their formation and dynamical evolution are still in their infancy. Aims. We investigate the giant impact stage for the growth of protoplanets, which includes strong scattering around low-mass stars. The aim is to clarify whether strong scattering around low-mass stars affects the orbital and mass distributions of the planets. Methods. We performed an N-body simulation of protoplanets by systematically surveying the parameter space of the stellar mass and surface density of protoplanets. Results. We find that protoplanets are often ejected after twice or three times the close-scattering around late M dwarfs. The ejection sets the upper limit of the largest planet mass. By adopting the surface density that linearly scales with the stellar mass, we find that as the stellar mass decreases, less massive planets are formed in orbits with higher eccentricities and inclinations. Under this scaling, we also find that a few close-in protoplanets are generally ejected. Conclusions. The ejection of protoplanets plays an important role in the mass distribution of super-Earths around late M dwarfs. The mass relation of observed close-in super-Earths and their central star mass is reproduced well by ejection.

scholarly journals Fundamental Mode and First Overtone Mode Cepheids in the Small Magellanic Cloud

1993 ◽  
Vol 139 ◽  
pp. 349-356
Author(s):  
H.A. Smith ◽  
N.A. Silbermann ◽  
S.R. Baird ◽  
J.A. Graham
Keyword(s):  
Frequency Distribution ◽  
Fundamental Mode ◽  
Surface Density ◽  
Variable Stars ◽  
Magellanic Cloud ◽  
Small Magellanic Cloud ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Photographic Survey ◽  
Lyrae Stars

AbstractWe report results of a new photographic survey of variable stars in a 1 x 1.3 degree region near the Northeast Arm of the Small Magellanic Cloud. We have discovered 133 new variable stars in this field and have determined periods and B lightcurves for 78 new and 72 previously known variables. At periods shorter than about 3 days, the Cepheid period-luminosity relation splits into two sequences. The brighter sequence is believed to be populated by stars pulsating in the first overtone radial mode, wherecis the fainter sequence is populated by fundamental mode pulsators. The peak in the Cepheid period-frequency distribution occurs near a period of 1.8 days. The surface density of RR Lyrae stars in this field is comparable to that in an outlying SMC field near NGC 121.

Motions of neutral hydrogen at high latitudes

1967 ◽  
Vol 31 ◽  
pp. 265-278 ◽  
Author(s):  
A. Blaauw ◽  
I. Fejes ◽  
C. R. Tolbert ◽  
A. N. M. Hulsbosch ◽  
E. Raimond
Keyword(s):  
Surface Density ◽  
Velocity Dispersion ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
High Latitudes ◽  
Low Velocity

Earlier investigations have shown that there is a preponderance of negative velocities in the hydrogen gas at high latitudes, and that in certain areas very little low-velocity gas occurs. In the region 100° <l< 250°, + 40° <b< + 85°, there appears to be a disturbance, with velocities between - 30 and - 80 km/sec. This ‘streaming’ involves about 3000 (r/100)2solar masses (rin pc). In the same region there is a low surface density at low velocities (|V| < 30 km/sec). About 40% of the gas in the disturbance is in the form of separate concentrations superimposed on a relatively smooth background. The number of these concentrations as a function of velocity remains constant from - 30 to - 60 km/sec but drops rapidly at higher negative velocities. The velocity dispersion in the concentrations varies little about 6·2 km/sec. Concentrations at positive velocities are much less abundant.

ATOMIZATION MODELLING OF LIQUID JETS USING A TWO-SURFACE-DENSITY APPROACH

2015 ◽  
Vol 25 (1) ◽  
pp. 47-80 ◽  
Author(s):  
Bejoy Mandumpala Devassy ◽  
Chawki Habchi ◽  
Eric Daniel
Keyword(s):  
Surface Density ◽  
Liquid Jets

Analysis of the Vulpecula Rift from a Photographic Survey of Proper Motions

1999 ◽  
Vol 118 (1) ◽  
pp. 421-431 ◽  
Author(s):  
A. Fresneau ◽  
R. Monier
Keyword(s):  
Proper Motions ◽  
Photographic Survey

scholarly journals Characterization of M dwarfs using optical mid-resolution spectra for exploration of small exoplanets

2020 ◽  
Author(s):  
Yohei Koizumi ◽  
Masayuki Kuzuhara ◽  
Masashi Omiya ◽  
Teruyuki Hirano ◽  
John Wisniewski ◽  
...  
Keyword(s):  
Sample Selection ◽  
Optical Spectra ◽  
Average Error ◽  
Spectral Energy ◽  
M Dwarfs ◽  
Energy Distributions ◽  
Fitting Procedures ◽  
Optical Region ◽  
Selection For

Abstract We present the optical spectra of 338 nearby M dwarfs, and compute their spectral types, effective temperatures (Teff), and radii. Our spectra were obtained using several optical spectrometers with spectral resolutions that range from 1200 to 10000. As many as 97% of the observed M-type dwarfs have a spectral type of M3–M6, with a typical error of 0.4 subtype, among which the spectral types M4–M5 are the most common. We infer the Teff of our sample by fitting our spectra with theoretical spectra from the PHOENIX model. Our inferred Teff is calibrated with the optical spectra of M dwarfs whose Teff have been well determined with the calibrations that are supported by previous interferometric observations. Our fitting procedures utilize the VO absorption band (7320–7570 Å) and the optical region (5000–8000 Å), yielding typical errors of 128 K (VO band) and 85 K (optical region). We also determine the radii of our sample from their spectral energy distributions. We find most of our sample stars have radii of <0.6 R⊙, with the average error being 3%. Our catalog enables efficient sample selection for exoplanet surveys around nearby M-type dwarfs.

Sign in / Sign up

Export Citation Format

Share Document