اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدA 1500 deg$^2$ Near Infrared Proper Motion Catalogue from the UKIDSS Large Area Survey
140
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
The UKIDSS Large Area Survey (LAS) began in 2005, with the start of the UKIDSS program as a 7 year effort to survey roughly 4000 deg$^2$ at high galactic latitudes in Y, J, H and K bands. The survey also included a significant quantity of 2-epoch J band observations, with an epoch baseline greater than 2 years to calculate proper motions. We present a near infrared proper motion catalogue for the 1500 deg$^2$ of the 2 epoch LAS data, which includes 135,625 stellar sources and a further 88,324 with ambiguous morphological classifications, all with motions detected above the 5$sigma$ level. We developed a custom proper motion pipeline which we describe here. Our catalogue agrees well with the proper motion data supplied for a 300 deg$^2$ subset in the current WFCAM Science Archive (WSA) tenth data release (DR10) catalogue, and in various optical catalogues, but it benefits from a larger matching radius and hence a larger upper proper motion detection limit. We provide absolute proper motions, using LAS galaxies for the relative to absolute correction. By using local 2nd order polynomial transformations, as opposed to linear transformations in the WSA, we correct better for any local distortions in the focal plane, not including the radial distortion that is removed by the UKIDSS pipeline. We present the results of proper motion searches for new brown dwarfs and white dwarfs. We discuss 41 sources in the WSA DR10 overlap with our catalogue with proper motions $>$300 $mas yr^{-1}$, several of which are new detections. We present 15 new candidate ultra-cool dwarf binary systems.
قيم البحث
اقرأ أيضاً
The UKIDSS Galactic Plane Survey (GPS) began in 2005 as a 7 year effort to survey ~1800 square degrees of the northern Galactic plane in the J, H, and K passbands. The survey included a second epoch of K band data, with a baseline of 2 to 8 years, fo
r the purpose of investigating variability and measuring proper motions. We have calculated proper motions for 167 Million sources in a 900 square degree area located at l > 60 degrees in order to search for new high proper motion objects. Visual inspection has verified 617 high proper motion sources (> 200 mas/yr) down to K=17, of which 153 are new discoveries. Among these we have a new spectroscopically confirmed T5 dwarf, an additional T dwarf with estimated type T6, 13 new L dwarf candidates, and two new common proper motion systems containing ultracool dwarf candidates. We provide improved proper motions for an additional 12 high proper motion stars that were independently discovered in the WISE dataset during the course of this investigation.
We have conducted a 4030-square-deg near-infrared proper motion survey using multi-epoch data from the Two Micron All-Sky Survey (2MASS). We find 2778 proper motion candidates, 647 of which are not listed in SIMBAD. After comparison to DSS images, we
find that 107 of our proper motion candidates lack counterparts at B-, R-, and I-bands and are thus 2MASS-only detections. We present results of spectroscopic follow-up of 188 targets that include the infrared-only sources along with selected optical-counterpart sources with faint reduced proper motions or interesting colors. We also establish a set of near-infrared spectroscopic standards with which to anchor near-infrared classifications for our objects. Among the discoveries are six young field brown dwarfs, five red L dwarfs, three L-type subdwarfs, twelve M-type subdwarfs, eight blue L dwarfs, and several T dwarfs. We further refine the definitions of these exotic classes to aid future identification of similar objects. We examine their kinematics and find that both the blue L and red L dwarfs appear to be drawn from a relatively old population. This survey provides a glimpse of the kinds of research that will be possible through time-domain infrared projects such as the UKIDSS Large Area Survey, various VISTA surveys, and WISE, and also through z- or y-band enabled, multi-epoch surveys such as Pan-STARRS and LSST.
The UKIRT Infrared Deep Sky Survey (UKIDSS) is the first of a new generation of infrared surveys. Here we combine the data from two UKIDSS components, the Large Area Survey (LAS) and the Galactic Cluster Survey (GCS), with 2MASS data to produce an in
frared proper motion survey for low mass stars and brown dwarfs. In total we detect 267 low mass stars and brown dwarfs with significant proper motions. We recover all ten known single L dwarfs and the one known T dwarf above the 2MASS detection limit in our LAS survey area and identify eight additional new candidate L dwarfs. We also find one new candidate L dwarf in our GCS sample. Our sample also contains objects from eleven potential common proper motion binaries. Finally we test our proper motions and find that while the LAS objects have proper motions consistent with absolute proper motions, the GCS stars may have proper motions which are significantly under-estimated. This is due possibly to the bulk motion of some of the local astrometric reference stars used in the proper motion determination.
Near-IR data of Classical Novae contain useful information about the ejected gas mass and the thermal emission by dust formed during eruption, and provide independent methods to classify the objects according to the colour of their progenitors, and t
he fading rate and features seen after eruption. The VISTA Variables in the Via Lactea survey (VVV) is a near-IR ESO Public Survey mapping the MW bulge and southern plane. Data taken during 2010-2011 covered the entire area in the JHKs bands plus some epochs in Ks-band of the ongoing VVV variability campaign. We used the novae list provided by VSX/AAVSO catalogue to search for all objects within the VVV area. We used the VVV data to create a near-IR catalogue of the known Galactic novae in the 562 sq.deg. area covered by VVV. The VVV near-IR catalogue of novae contains JHKs photometry of 93 objects completed as of December 2012. We also checked in the ongoing VVV variability campaign for the light-curves of novae that erupted in the last years. VVV images can also be used to discover and study novae by searching for the expanding shell. Since objects are seen at different distances and reddening levels, the colour-magnitude and colour-colour diagrams show the novae spread in magnitude as well as in colour. Dereddened colours and reddening-free indices were used with caution and cannot be a good approach in all cases since the distance and spectral features prevent more conclusive results for some extreme objects. Light-curves for some recent novae are presented. Thanks to its high spatial resolution in the near-IR, and large Ks-range, the VVV survey can be a major contributor for the search and study of novae in the most crowded and high-extinction regions of the Milky Way. The VVV survey area contains ~35 of all known novae in the Galaxy.
We report the discovery of 47 new T dwarfs in the Fourth Data Release (DR4) from the Large Area Survey (LAS) of the UKIRT Infrared Deep Sky Survey with spectral types ranging from T0 to T8.5. These bring the total sample of LAS T dwarfs to 80 as of D
R4. In assigning spectral types to our objects we have identified 8 new spectrally peculiar objects, and divide 7 of them into two classes. H2O-H-early have a H2O-H index that differs with the H2O-J index by at least 2 sub-types. CH4-J-early have a CH4-J index that disagrees with the H20-J index by at least 2 subtypes. We have ruled out binarity as a sole explanation for both types of peculiarity, and suggest that they may represent hitherto unrecognised tracers of composition and/or gravity. Clear trends in z(AB)-J and Y-J are apparent for our sample, consistent with weakening absorption in the red wing of the KI line at 0.77microns with decreasing effective temperature. We have used our sample to estimate space densities for T6-T9 dwarfs. By comparing our sample to Monte-Carlo simulations of field T dwarfs for various mass functions of the form phi(M) propto M^-alpha, we have placed weak constraints on the form of the field mass function. Our analysis suggests that the substellar mass function is declining at lower masses, with negative values of alpha preferred. This is at odds with results for young clusters that have been generally found to have alpha > 0.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
