393 research outputs found
Determination of Kinematic Distances of Pre-Main Sequence Stars in Lupus
No full textInternational audienceThe problem of the determination of distances has always played a central role in astronomy. However, little recent progress has been made in the distance determination of faint young stellar objects such as pre-main sequence (PMS) stars. A precise determination of distances is required to accurately determine the main physical parameters of stars (luminosity, temperature, mass and age) and to trace the evolutionary tracks of young stars. The procedure that we use here to derive individual parallaxes is based on the convergent point strategy which makes full use of the directly observed data: position, proper motion and radial velocity. %Z Ducourant, C., et al. 2005, A&A, 438, 769 Jones, D. H. P. 1971, MNRAS, 152, 231 Bertout, C., & Genova, F. 2006, A&A, 460, 49
Determination of Kinematic Distances of Pre-Main Sequence Stars in Lupus
No full textInternational audienceThe problem of the determination of distances has always played a central role in astronomy. However, little recent progress has been made in the distance determination of faint young stellar objects such as pre-main sequence (PMS) stars. A precise determination of distances is required to accurately determine the main physical parameters of stars (luminosity, temperature, mass and age) and to trace the evolutionary tracks of young stars. The procedure that we use here to derive individual parallaxes is based on the convergent point strategy which makes full use of the directly observed data: position, proper motion and radial velocity. %Z Ducourant, C., et al. 2005, A&A, 438, 769 Jones, D. H. P. 1971, MNRAS, 152, 231 Bertout, C., & Genova, F. 2006, A&A, 460, 49
VizieR Online Data Catalog: rho Oph proper motions and photometry (Ducourant+, 2017)
No full textVizieR On-line Data Catalog: J/A+A/597/A90. Originally published in: 2017A&A...597A..90DTables 6 lists the J,H,Ks photometry for the 68 kinematic members and 14 candidate members of the Rho Ophiuchi core from 2MASS or derived in this work together with the AllWISE (W1,W2,W3,W4) photometry. Column (1) provides identifications of the objects. Columns (2,4,6) presents the J,H,Ks photometry from 2MASS and columns (3,5,7) their associated standard errors; if predeceded by an asterisk the photometry was derived in this work. Columns (8, 10, 12) list AllWISE (w1,w2,w3,w4) photometry unless predeceded by an asterisk (WISE) and columns (9, 11, 13) the associated standard errors. Tables 7 Lists the 68 members and 14 candidate members, their astrometric solution and their membership probability. Column (1) provides identifications of the objects. Columns (2,3) present the J2000 Right ascension and Declination for the mean epochs given in columns (7,8) (in years) and column (4) the mean standard error on position (in mas). Columns (5,6) list the proper motions and internal standard errors (in mas/yr). Column (9) presents the 2MASS Ks photometry (*= this work), column (10) lists the number of different epochs of observations used for the derivation of proper motions, column (11) the time base of these observations and column (12) the membership probability. Tables 8 lists the evolutionary status of the 68 kinematic members and 14 candidate members. Columns (1) and (2) provide identifications of the objects. Column (3) list the (RA,DE) positions extracted from table 7, column (4) (status) lists the young stellar object status as given by CDS-Simbad and Column (5) (Class) the SED class of the object (classes preceded by an asterisk were assigned in this work). The corresponding references are given in Column (6) . In Column (7) we list the spectral type found in the litterature and in Col. (8) the references. Note . a: this object is classified as class II by Bontemps et al. (2001, Cat. J/A+A/372/173) but was classified as class III by our algorithm. b: this object is classified as class I by Bontemps et al. (2001, Cat. J/A+A/372/173) but was classified as class II by our algorithm. Note to all Tables. Objects not detected by 2MASS or WISE were searched in the 2MASS 6X (Cutri & IPAC/WISE Science Data Center Team 2012, Cat. VII/233) and the UKIDSS (Lawrence et al., 2007, Cat. II/319) catalogues and attributed their identificators. A local identificator (BXhhmmss.sss+dddmmss.ss) was attributed to the faintest source not found in these catalogues. (4 data files)
Photometric observations and frequency analysis of the Delta Scuti star IP UMa
No full textCommunications in Asteroseismology, Vol. 161, p. 17-22IP UMa is a Delta Scuti star discovered by Hipparcos. 2642 observations of this target were acquired with the 20cm telescope of the Nea Lesbos Observatory in 10 nights from June 2 to July 9, 2009 using the Bessel V filter. These data confirmed the pulsation frequency of the star listed in the Hipparcos Catalogue (10 c/d)
Photometric observations and frequency analysis of the Delta Scuti star IP UMa
No full textCommunications in Asteroseismology, Vol. 161, p. 17-22IP UMa is a Delta Scuti star discovered by Hipparcos. 2642 observations of this target were acquired with the 20cm telescope of the Nea Lesbos Observatory in 10 nights from June 2 to July 9, 2009 using the Bessel V filter. These data confirmed the pulsation frequency of the star listed in the Hipparcos Catalogue (10 c/d)
Photometric observations and frequency analysis of the Delta Scuti star IP UMa
No full textCommunications in Asteroseismology, Vol. 161, p. 17-22IP UMa is a Delta Scuti star discovered by Hipparcos. 2642 observations of this target were acquired with the 20cm telescope of the Nea Lesbos Observatory in 10 nights from June 2 to July 9, 2009 using the Bessel V filter. These data confirmed the pulsation frequency of the star listed in the Hipparcos Catalogue (10 c/d)
Minutes of the 16.5th intermediate CU4 Extended Objects (EO) meeting
No full textGAIA-C4-MN-LAB-CD-009-01, 201
VizieR Online Data Catalog: Gaia GraL. II. Known multiply imaged quasars (Ducourant+, 2018)
No full textVizieR On-line Data Catalog: J/A+A/618/A56. Originally published in: 2018A&A...618A..56DTables 4 provides the compiled list of 478 known gravitationally lensed systems (GL), including candidates (each line corresponds to an image of the lense) together with informations from the Gaia DR2 whenever a source was found at less than 0.5 arcsec from the literature's position of the image. (1) Name, (2) ref - bibliographic reference (* designates candidates), (3) Nim - number of images of the lens in the literature, (4) Gaia DR2 SourceId, (5,6) ICRS positions from the Gaia DR2 at epoch 2015.5, (7,8,9) Gaia G, GBP, GRP magnitudes and standard errors (calculated by CDS). (1 data file)
Revisiting TW Hydrae in light of new astrometric data
No full textInternational audienceOur efforts in the present work focused mainly on refining and improving the previous description and understanding of the stellar association TW Hydrae (TWA) including a very detailed membership analysis and its dynamical and evolutionary age.To achieve our objectives in a fully reliable way we take advantage of our own astrometric measurements (Ducourant et al. 2013) performed with NTT/EFOSC2 - ESO (La Silla - Chile) spread over three years (2007 - 2010) and of those published in the literature.A very detailed membership analysis based on the convergent point strategy as developed by our team (Galli et al. 2012, 2013) allowed us to define a consistent kinematic group containing 31 stars among the 44 proposed as TWA member in the literature. Assuming that our sample of stars may be contaminated by non-members and to get rid of the particular influence of each star we applied a Jacknife resampling technique generating 2000 random lists of 13 stars taken from our 16 stars and calculated for each the epoch of convergence when the radius is minimum. The mean of the epochs obtained and the dispersion about the mean give a dynamical age of 7.5± 0.7 Myr for the association that is in good agreement with the previous traceback age (De La Reza et al. 2006). We also estimated age for TWA moving group members from pre-main sequence evolutionary models (Siess et al. 2000) and find a mean age of 7.4± 1.2 Myr. These results show that the dynamical age of the association obtained via the traceback technique and the average age derived from theoretical evolutionary models are in good agreement
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