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Pre-main sequence star Proper Motion Catalogue
We measured the proper motions of 1250 pre-main sequence (PMS) stars andof 104 PMS candidates spread over all-sky major star-forming regions.This work is the continuation of a previous effort where we obtainedproper motions for 213 PMS stars located in the major southernstar-forming regions. These stars are now included in this present workwith refined astrometry. The major upgrade presented here is theextension of proper motion measurements to other northern and southernstar-forming regions including the well-studied Orion and Taurus-Aurigaregions for objects as faint as V≤16.5. We improve the precision ofthe proper motions which benefited from the inclusion of newobservational material. In the PMS proper motion catalogue presentedhere, we provide for each star the mean position and proper motion aswell as important photometric information when available. We providealso the most common identifier. The rms of proper motions vary from 2to 5 mas/yr depending on the available sources of ancient positions anddepending also on the embedding and binarity of the source. With thiswork, we present the first all-sky catalogue of proper motions of PMSstars.
| The Status of ROSAT X-ray Active Young Stars toward Taurus-Auriga
We present an astrometric study of the candidates of T Tauri stars (TTS)and non-TTS X-ray sources around Tau-Aur, based on the HipparcosCatalogue and the ACT Reference Catalogue. The ROSAT selected X-raysources are found to be a mixed population. A few of them areassociated with the Tau-Aur or Orion Star Forming Regions (SFR). Some,with distances similar to that of Tau-Aur but with discrepant propermotions, are probable or sure Pleiades super-cluster members or otherlate type young active stars with unresolved nature, more likely tooriginate in rapidly moving cloudlets, or else having originated fromdifferent sites other than Tau-Aur and moved to the present locations. Agood many of the non-TTS X-ray sources are considered as Hyades clustermembers. Some TTS candidates could be foreground pre-main sequencestars or actually young dwarfs not yet depleted of their Lithium. Underthe hypothesis that the sources we studied are representative of theROSAT selected TTS candidates discovered in the outskirts of the Tau-Aurregion, we conclude that only up to one third of the weak-line TTScandidates could be expected to be physically associated with theTau-Aur association. Along with the parallax and proper motion analysisof the non-TTS X-ray sources around the Tau-Aur SFR, our result suggeststhat the vast majority of the young active X-ray sources within anangular diameter of about 30 ° of the Tau-Aur SFR, belong to fourmain subgroups that are spatially separate.
| Newly discovered candidate weak-line T Tauri stars in the surrounding area of the Taurus-Auriga region
We present results of an extensive search for weak-line T Tauri stars(WTTS) in the outskirts of the Taurus-Auriga molecular cloud on thebasis of the ROSAT All-Sky Survey Bright Source Catalog. Our surveyedregion extends from 2() h40() m to 5() h40() m in right ascension andfrom 10(deg) to 40(deg) in declination, with the central part ofTaurus-Auriga (4() h
| An Optical Atlas of Extreme Ultraviolet Explorer (EUVE) Sources
The Extreme Ultraviolet Explorer (EUVE) has been detecting EUV sourcessince its launch in June 1992. Positions of 540 sources have been madeavailable to the community by the EUVE team. We have extracted 7' X 7'images centered on these 540 EUVE sources from the Space TelescopeScience Institute digitized sky archives. We present these images asmosaic finder charts to aid observers trying to identify EUVE sources,or to characterize known sources. (SECTION: Atlases)
| The Second Extreme-Ultraviolet Explorer Source Catalog
We present the second catalog of extreme-ultraviolet objects detected bythe Extreme-Ultraviolet Explorer. The data include (1) all-sky surveydetections from the initial 6 month scanner-survey phase, (2) additionalscanner detections made subsequently during specially programmedobservations designed to fill in low-exposure sky areas of the initialsurvey, (3) sources detected with deep-survey-telescope observationsalong the ecliptic, (4) objects detected by the scanner telescopesduring targeted spectroscopy observations, and ( 3) other observations.We adopt an innovative source detection method that separates the usuallikelihood function into two parts: an intensity diagnostic and aprofile diagnostic. These diagnostics allow each candidate detection tobe tested separately for both signal-to-noise ratio and conformance withthe known instrumental point-spread function. We discuss the dependenceof the false-alarm rate and the survey's completeness on the survey'ssensitivity threshold. We provide three lists of the EUV sourcesdetected: the all-sky survey detections, the deep-survey detections, andsources detected during other phases of the mission. Each list givespositions and intensities in each wave band. The total number of objectslisted is 734. For approximately 65% of these we also provide plausibleoptical, UV, radio, and/or X-ray identifications.
| The first Extreme Ultraviolet Explorer source catalog
The Extreme Ultraviolet Explorer (EUVE) has conducted an all-sky surveyto locate and identify point sources of emission in four extremeultraviolet wavelength bands centered at approximately 100, 200, 400,and 600 A. A companion deep survey of a strip along half the eclipticplane was simultaneously conducted. In this catalog we report thesources found in these surveys using rigorously defined criteriauniformly applied to the data set. These are the first surveys to bemade in the three longer wavelength bands, and a substantial number ofsources were detected in these bands. We present a number of statisticaldiagnostics of the surveys, including their source counts, theirsensitivites, and their positional error distributions. We provide aseparate list of those sources reported in the EUVE Bright Source Listwhich did not meet our criteria for inclusion in our primary list. Wealso provide improved count rate and position estimates for a majorityof these sources based on the improved methodology used in this paper.In total, this catalog lists a total of 410 point sources, of which 372have plausible optical ultraviolet, or X-ray identifications, which arealso listed.
| Extreme Ultraviolet Explorer Bright Source List
Initial results from the analysis of the Extreme Ultraviolet Explorer(EUVE) all-sky survey (58-740 A) and deep survey (67-364 A) arepresented through the EUVE Bright Source List (BSL). The BSL contains356 confirmed extreme ultraviolet (EUV) point sources with supportinginformation, including positions, observed EUV count rates, and theidentification of possible optical counterparts. One-hundred twenty-sixsources have been detected longward of 200 A.
| U, V, W velocity components for the old disk using radial velocities of 1295 stars in the three cardinal Galactic directions
New radial velocities are presented for 1295 stars chosen at random nearthe three cardinal Galactic directions of l = 180 deg, b = 0; l = 90deg, b = 0 deg; and b = 90 deg, giving the distribution in U, V, and W,respectively, from the radial velocities alone. The measurements weremade with the coude spectrograph of the Mount Wilson 100 in. Hookerreflector. The purpose of the program is to set limits on the densitynormalization in the solar neighborhood of the old thin disk, the oldthick disk, and the halo. Many more high-velocity stars are present inthe unbiased sample than expected from previous estimates of thenormalization. The data suggest the density ratios in the solarneighborhood to be about 90 percent, 10 percent, and about 0.5 percentfor the thin disk, thick disk, and halo populations, respectively.
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Наблюдательные данные и астрометрия
| Созвездие: | Телец |
| Прямое восхождение: | 05h36m51.68s |
| Склонение: | +23°26'05.4" |
| Видимая звёздная величина: | 8.818 |
| Собственное движение RA: | 3.3 |
| Собственное движение Dec: | -37.8 |
| B-T magnitude: | 9.685 |
| V-T magnitude: | 8.89 |
Каталоги и обозначения:
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