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TYC 1242-382-1


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High-Resolution Optical Observations of Extreme-Ultraviolet-selected Active Late-type Stars
We present high-resolution optical spectra of EUV-selected late-typestars. We have detected seven new spectroscopic binaries, including apair of F stars and an RS Canum Venaticorum candidate. Many of the starsin our sample show remarkable Hα emission with equivalent widthsup to 8 Å. Several sources show strong He I 5876 Å emission.We use cross-correlation techniques to estimate line-of-sight rotationalvelocities and find that they range from less than 5 to over 80 kms-1. Several of the stars show a strong Li 6707 Å line,which we use to determine their Li abundances. The EUV-to-bolometricluminosity, a measure of the coronal heating efficiency, is as high as10-3. The present sample extends the EUV-selected late-typestars to lower Rossby numbers and makes the coronal saturation boundarybetter pronounced. Our results indicate that there is a drop in the EUVemission from the corona in late M dwarfs possibly because of a changein the nature of the magnetic dynamo in fully convective stars.

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.

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Gözlemler ve gökölçümü verileri

Takýmyýldýz:Boga
Sað Açýklýk:03h30m56.10s
Yükselim:+18°47'57.9"
Görünürdeki Parlaklýk:8.138
Uzaklýk:92.336 parsek
özdevim Sað Açýklýk:128.1
özdevim Yükselim:-72.2
B-T magnitude:8.792
V-T magnitude:8.192

Kataloglar ve belirtme:
Özgün isimleri
TYCHO-2 2000TYC 1242-382-1
USNO-A2.0USNO-A2 1050-00944602
HIPHIP 16374

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