- ID:
- ivo://CDS.VizieR/J/A+A/409/169
- Title:
- UBVRI light curves of AA Tau in 1999
- Short Name:
- J/A+A/409/169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a synoptic study of the photometric and spectroscopic variability of the classical T Tauri star AA Tau on timescales ranging from a few hours to several weeks. The AA Tau light curve had been previously shown to vary with a 8.2d period, exhibiting a roughly constant brightness level, interrupted by quasi-cyclic fading episodes, which we interpreted as recurrent eclipses of the central star by the warped inner edge of its accretion disk (Bouvier et al. 1999, Cat. <J/A+A/349/619>). Our observations show the system is dynamic and presents non-stationary variability both in the photometry and spectroscopy.
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- ID:
- ivo://CDS.VizieR/J/AJ/126/2971
- Title:
- UBVRI photometry of 131 Herbig Ae/Be
- Short Name:
- J/AJ/126/2971
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of 108 Herbig Ae/Be candidate stars identified in the Pico dos Dias Survey (Gregorio-Hete et al., 1992AJ....103..549G; Torres et al., 1995AJ....109.2146T and 1999, Special Publ. 10, Rio de Janeiro: Obs. Nac.), together with 19 previously known candidates and four objects selected from the IRAS Faint Source Catalog (<II/156>). These 131 stars were observed with low- and/or medium-resolution spectroscopy, and we complement these data with high-resolution spectra of 39 stars.
- ID:
- ivo://CDS.VizieR/J/A+AS/128/561
- Title:
- UBVRI photometry of southern T Tauri stars
- Short Name:
- J/A+AS/128/561
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present full tables of the photoelectric photometry of T Tauri Stars observed in the 0.5m telescope at Laboratorio Nacional de Astronomia (Brazil). The photometry was performed with the instrument FOTRAP (Jablonski et al., 1994PASP..106.1172J, see text). For a description of the UBVRI photometric system, see e.g. <GCPD/08>
- ID:
- ivo://CDS.VizieR/J/A+A/479/827
- Title:
- UBVR light curves of weak-line T Tauri stars
- Short Name:
- J/A+A/479/827
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- T Tauri stars exhibit variability on all timescales, whose origin is still debated. On WTTS the variability is fairly simple and attributed to long-lived, ubiquitous cool spots. We investigate the long term variability of WTTS, extending up to 20 years in some cases, characterize it statistically and discuss its implications for our understanding of these stars. We have obtained a unique, homogeneous database of photometric measurements for WTTS extending up to 20-years. It contains more than 9000 UBVR observations of 48 WTTS. All the data were collected at Mount Maidanak Observatory (Uzbekistan) and they constitute the longest homogeneous record of accurate WTTS photometry ever assembled. Definitive rotation periods for 35 of the 48 stars are obtained. Phased light curves over 5 to 20 seasons are now available for analysis. Light curve shapes, amplitudes and colour variations are obtained for this sample and various behaviors exhibited, discussed and interpreted. Our main conclusion is that most WTTS have very stable long term variability with relatively small changes of amplitude or mean light level. The long term variability seen reflects modulation in the cold spot distributions. Photometric periods are stable over many years, and the phase of minimum light can be stable as well for several years. On the long term, spot properties do change in subtle ways, leading to secular variations in the shape and amplitudes of the light curves.
- ID:
- ivo://CDS.VizieR/J/MNRAS/503/270
- Title:
- UKIDSS JHK photometry of W33A
- Short Name:
- J/MNRAS/503/270
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- W33A is a well-known example of a high-mass young stellar object showing evidence of a circumstellar disc. We revisited the -band NIFS/Gemini North observations of the W33A protostar using principal components analysis tomography and additional post-processing routines. Our results indicate the presence of a compact rotating disc based on the kinematics of the CO absorption features. The position-velocity diagram shows that the disc exhibits a rotation curve with velocities that rapidly decrease for radii larger than 0.1" (~250AU) from the central source, suggesting a structure about four times more compact than previously reported.We derived a dynamical mass of 10.0^+4.1^_-2.2_M_{sun}_ for the "disc+protostar" system, about ~33% smaller than previously reported, but still compatible with high-mass protostar status. A relatively compact H_2_ wind was identified at the base of the large-scale outflow of W33A, with a mean visual extinction of ~63mag. By taking advantage of supplementary near-infrared maps, we identified at least two other point-like objects driving extended structures in the vicinity of W33A, suggesting that multiple active protostars are located within the cloud. The closest object (SourceB) was also identified in the NIFS field of view as a faint pointlike object at a projected distance of ~7000AU from W33A, powering extended K-band continuum emission detected in the same field. Another source (SourceC) is driving a bipolar H_2_ jet aligned perpendicular to the rotation axis of W33A.
- ID:
- ivo://CDS.VizieR/J/A+AS/101/59
- Title:
- 1-20um observations of Herbig-Haro objects
- Short Name:
- J/A+AS/101/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For 58 exciting sources of Herbig-Haro objects/jets (HHES) we present a catalogue of photometric data for the infrared spectral bands JHKLMNQ (1-20 um). This catalog is based on our own observations and published information available up to May 1992. For each source, these data are presented in chronological order. In addition to the broad-band data, narrow-band N(8-13 um) photometric data are also provided. The flux calibration for each observational equipment is explicitly noted as the diaphragm sizes are used. The same kind of information for the established members of the FU Ori class is complementing the HHES catalogue. The frequency of observations and the photometric quality of the catalogued data are shortly discussed.
- ID:
- ivo://CDS.VizieR/J/A+A/333/619
- Title:
- Upper Scorpius OB association Lithium survey
- Short Name:
- J/A+A/333/619
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an intermediate resolution spectroscopic survey for pre-main sequence (PMS) stars in the Upper Scorpius OB association. In a 160 square-degree area we were able to identify 39 new PMS stars by follow up observations of X-ray selected stars with the multi object spectrograph FLAIR at the UK Schmidt Telescope. We also investigated the completeness of our X-ray selected sample by observing more than 100 stars that were not detected as X-ray sources, but have proper motions indicating membership to Upper Sco. While the new X-ray selected PMS stars with known proper motions have kinematics consistent with membership, none of the X-ray quiet proper motion candidates is a PMS star. We conclude that our X-ray selected sample of PMS stars seems to be rather complete. For stars in the magnitude interval 11.5<~B<~13.5 we derive a conservative lower limit of 75% completeness.
- ID:
- ivo://CDS.VizieR/J/AJ/124/404
- Title:
- Upper Scorpius OB association Lithium survey. II.
- Short Name:
- J/AJ/124/404
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the stellar population and star formation history of the Upper Scorpius OB association, the most nearby region of recent massive star formation, over the full stellar mass range from 0.1 to 20M_{sun}_. The first part of this paper describes an extension of our large spectroscopic survey (Preibisch et al., published in 2001, Cat. <J/AJ/121/1040>) for low-mass pre-main-sequence (PMS) stars in Upper Scorpius. Using the multiobject spectrograph 2dF at the Anglo-Australian Telescope, we obtained spectra of 469 stars with magnitudes R=12.5-18.0 in a 6{deg}^2^ area, on he nights of 2001 May 16-17. Among these, we find 68 new PMS stars, nearly all of them M-type stars, by their strong lithium absorption lines. The total area covered by our 2dF survey is now 9 deg2 and contains 166 new PMS stars. Combining these results with our earlier investigation (Preibisch & Zinnecker, 1999AJ....117.2381P) yields a sample of 250 PMS stars in the mass range ~0.2 to ~2M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/A+AS/104/557
- Title:
- uvby-beta photometry in star-forming regions
- Short Name:
- J/A+AS/104/557
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+AS/145/187
- Title:
- uvby-{beta} photometry of WTTS
- Short Name:
- J/A+AS/145/187
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present uvby-{beta} photometry of 116 X-ray flux-selected active stars in the directions of the Orion (40), Taurus-Auriga (58) and Scorpius OB2-2 (18) star forming regions. Additionally, we give near IR JHK photometry of 20 active stars in the Taurus-Auriga direction. The program stars were selected from the ROSAT All Sky Survey and EINSTEIN X-ray surveys and are spectroscopically confirmed weak-line T Tauri stars and weak-line T Tauri star candidates. The photometry confirms the young nature of the program stars and also indicates that a significant fraction of the sample could be foreground objects. The data given here probably represent the largest homogeneous uvby-{beta} photometric sample of new WTTS and WTTS candidates. Many objects in the sample are observed photometrically for the first time.
