Spectroscopic distances of nearby ultracool dwarfs
نویسندگان
چکیده
We present updated results of spectroscopic follow-up observations of a sample of 45 M dwarf candidates identified by Phan-Bao et al. (2003) based on the DENIS photometry and proper motion measurements. Forty one of these are nearby late-M dwarfs (d<30 pc) with spectral types ranging from M5.0 to M8.5 computed from the spectral indices. One contaminant is probably an F-G main sequence star reddened by intervening dust and three stars that were not observed have previous classifications as M dwarfs in the literature. In this paper, we identify three M7.5, five M8.0, one M8.5 dwarf and confirm two new M8.0 dwarf members of the 25 pc volume.
منابع مشابه
Discovery of new nearby L and late - M dwarfs at low Galactic latitude
We report new nearby L and late-M dwarfs (dphot 6 30 pc) discovered by our search for nearby ultracool dwarfs (I − J > 3.0, later than M8.0) at low Galactic latitude (|b| < 15◦) over 4,800 square degrees in the DENIS database. We used lateM (>M8.0), L, and T dwarfs with accurate trigonometric parallaxes to calibrate the MJ versus I − J colour-luminosity relation. The resulting photometric dista...
متن کاملDiscovery of new nearby L and late - M dwarfs at low Galactic latitude from the DENIS database
We report new nearby L and late-M dwarfs (dphot 6 30 pc) discovered in our search for nearby ultracool dwarfs (I − J > 3.0, later than M8.0) at low Galactic latitude (|b| < 15◦) over 4,800 square degrees in the DENIS database. We used lateM (>M8.0), L, and T dwarfs with accurate trigonometric parallaxes to calibrate the MJ versus I − J colour-luminosity relation. The resulting photometric dista...
متن کاملStar Formation via the Little Guy: A Bayesian Study of Ultracool Dwarf Imaging Surveys for Companions
I have undertaken a comprehensive statistical investigation of the ultracool dwarf companion distribution (spectral type M6 and later). Utilizing a Bayesian algorithm, I tested models of the companion distribution against data from an extensive set of space and ground-based imaging observations of nearby ultracool dwarfs. My main conclusions are fivefold: 1) Confirm that the concentration of hi...
متن کاملNew Neighbors from 2MASS: Activity and Kinematics at the Bottom of the Main Sequence
We have combined 2MASS and POSS II data in a search for nearby ultracool (later than M6.5) dwarfs with Ks < 12. Spectroscopic follow-up observations identify 53 M7 to M9.5 dwarfs and seven L dwarfs. The observed space density is 0.0045 ± 0.0008 M8-M9.5 dwarfs per cubic parsec, without accounting for biases, consistent with a mass function that is smooth across the stellar/substellar limit. We s...
متن کاملVolume-limited radio survey of ultracool dwarfs
Aims. We aim to increase the sample of ultracool dwarfs studied in the radio domain to allow a more statistically significant understanding of the physical conditions associated with these magnetically active objects. Methods. We conducted a volume-limited survey at 4.9 GHz of 32 nearby ultracool dwarfs with spectral types covering the range M7 – T8. A statistical analysis was performed on the ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2005