Detection of Massive Tidal Tails around the Globular Cluster Palomar 5 with Sloan Digital Sky Survey Commissioning Data

AbstractThe study of sub-structures in the stellar halo of the Milky Way has made a lot of progress in recent years, especially since surveys like the Sloan Digital Sky Survey became available. In this paper we focus on the newly discovered tidal tails of the Galactic globular cluster NGC 5466. By means of numerical simulations we reproduce the tidal tails, which are the longest tails associated with a globular cluster known (>45°) and hereby finding a possible progenitor of NGC 5466 and analyse its stability. We show that perigalactic passages are the dominant process in the slow dissolution of NGC 5466. Furthermore we use the position of the tails to verify the accuracy of the observationally determined proper motion. The proper motion has to be refined only slightly (within their stated error-margin) to match the location of the tidal tails.

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J-PLUS: Identification of low-metallicity stars with artificial neural networks using SPHINX

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833368 ◽

2019 ◽

Vol 622 ◽

pp. A182 ◽

Cited By ~ 8

Author(s):

D. D. Whitten ◽

V. M. Placco ◽

T. C. Beers ◽

A. L. Chies-Santos ◽

C. Bonatto ◽

...

Keyword(s):

Globular Cluster ◽

Effective Temperature ◽

Spectroscopic Studies ◽

Sloan Digital Sky Survey ◽

Intermediate Band ◽

Medium Resolution ◽

Sky Survey ◽

Data Release ◽

Low Metallicity ◽

Selection Of

Context. We present a new methodology for the estimation of stellar atmospheric parameters from narrow- and intermediate-band photometry of the Javalambre Photometric Local Universe Survey (J-PLUS), and propose a method for target pre-selection of low-metallicity stars for follow-up spectroscopic studies. Photometric metallicity estimates for stars in the globular cluster M15 are determined using this method. Aims. By development of a neural-network-based photometry pipeline, we aim to produce estimates of effective temperature, Teff, and metallicity, [Fe/H], for a large subset of stars in the J-PLUS footprint. Methods. The Stellar Photometric Index Network Explorer, SPHINX, was developed to produce estimates of Teff and [Fe/H], after training on a combination of J-PLUS photometric inputs and synthetic magnitudes computed for medium-resolution (R ~ 2000) spectra of the Sloan Digital Sky Survey. This methodology was applied to J-PLUS photometry of the globular cluster M15. Results. Effective temperature estimates made with J-PLUS Early Data Release photometry exhibit low scatter, σ(Teff) = 91 K, over the temperature range 4500 < Teff (K) < 8500. For stars from the J-PLUS First Data Release with 4500 < Teff (K) < 6200, 85 ± 3% of stars known to have [Fe/H] < −2.0 are recovered by SPHINX. A mean metallicity of [Fe/H] = − 2.32 ± 0.01, with a residual spread of 0.3 dex, is determined for M15 using J-PLUS photometry of 664 likely cluster members. Conclusions. We confirm the performance of SPHINX within the ranges specified, and verify its utility as a stand-alone tool for photometric estimation of effective temperature and metallicity, and for pre-selection of metal-poor spectroscopic targets.

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New Insights on the Draco Dwarf Spheroidal Galaxy from the Sloan Digital Sky Survey: A Larger Radius and No Tidal Tails

The Astronomical Journal ◽

10.1086/323715 ◽

2001 ◽

Vol 122 (5) ◽

pp. 2538-2553 ◽

Cited By ~ 87

Author(s):

Michael Odenkirchen ◽

Eva K. Grebel ◽

Daniel Harbeck ◽

Walter Dehnen ◽

Hans-Walter Rix ◽

...

Keyword(s):

Sloan Digital Sky Survey ◽

Sky Survey ◽

Tidal Tails

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Gaia DR2 orbital properties for field stars with globular cluster-like CN band strengths

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935417 ◽

2019 ◽

Vol 624 ◽

pp. L9 ◽

Cited By ~ 8

Author(s):

A. Savino ◽

L. Posti

Keyword(s):

Globular Cluster ◽

Globular Clusters ◽

Milky Way ◽

Light Element ◽

Small Population ◽

Sloan Digital Sky Survey ◽

Element Abundances ◽

Halo Stars ◽

Sky Survey ◽

Gaia Dr2

Context. Large spectroscopic surveys of the Milky Way have revealed that a small population of stars in the halo have light element abundances comparable to those found in globular clusters. The favoured explanation for the peculiar abundances of these stars is that they originated inside a globular cluster and were subsequently lost. Aims. Using orbit calculations we assess the likelihood that an existing sample of 57 field stars with globular cluster-like CN band strength originated in any of the currently known Milky Way globular clusters. Methods. Using Sloan Digital Sky Survey and Gaia data, we determine orbits and integrals of motion of our sample of field stars, and use these values and metallicity to identify likely matches to globular clusters. The pivot hypothesis is that had these stars been stripped from such objects, they would have remained on very similar orbits. Results. We find that ∼70% of the sample of field stars have orbital properties consistent with the halo of the Milky Way; however, only 20 stars have likely orbital associations with an existing globular cluster. The remaining ∼30% of the sample have orbits that place them in the outer Galactic disc. No cluster of similar metallicity is known on analogous disc orbits. Conclusions. The orbital properties of the halo stars seem to be compatible with the globular cluster escapee scenario. The stars in the outer disc are particularly surprising and deserve further investigation to establish their nature.

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Intrinsic Characteristics of Quasars Redshifts

JOURNAL OF ADVANCES IN PHYSICS ◽

10.24297/jap.v4i3.2020 ◽

2014 ◽

Vol 4 (3) ◽

pp. 655-661

Author(s):

Waleed Elsanhoury

Keyword(s):

Absolute Magnitude ◽

Sloan Digital Sky Survey ◽

Strong Correlations ◽

Sky Survey

Using Sloan Digital Sky Survey SDSS catalog, some intrinsic characteristics of Quasars (10,000 points) are developed of these are the strong correlations between redshifts and other parameters, e.g. combined magnitude, luminosity, and absolute magnitude .Moreover ,the Karlsson peak of our sample is also computed.

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Characterizing the abundance, properties, and kinematics of the cool circumgalactic medium of galaxies in absorption with SDSS DR16

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab871 ◽

2021 ◽

Vol 504 (1) ◽

pp. 65-88

Author(s):

Abhijeet Anand ◽

Dylan Nelson ◽

Guinevere Kauffmann

Keyword(s):

Formation Rate ◽

Sloan Digital Sky Survey ◽

Gas Absorption ◽

Dark Matter Halo ◽

Star Forming ◽

Sky Survey ◽

Optical Continuum ◽

Circumgalactic Medium ◽

Emission Line Galaxies ◽

Red Galaxies

ABSTRACT In order to study the circumgalactic medium (CGM) of galaxies we develop an automated pipeline to estimate the optical continuum of quasars and detect intervening metal absorption line systems with a matched kernel convolution technique and adaptive S/N criteria. We process ∼ one million quasars in the latest Data Release 16 (DR16) of the Sloan Digital Sky Survey (SDSS) and compile a large sample of ∼ 160 000 Mg ii absorbers, together with ∼ 70 000 Fe ii systems, in the redshift range 0.35 < zabs < 2.3. Combining these with the SDSS DR16 spectroscopy of ∼1.1 million luminous red galaxies (LRGs) and ∼200 000 emission line galaxies (ELGs), we investigate the nature of cold gas absorption at 0.5 < z < 1. These large samples allow us to characterize the scale dependence of Mg ii with greater accuracy than in previous work. We find that there is a strong enhancement of Mg ii absorption within ∼50 kpc of ELGs, and the covering fraction within 0.5rvir of ELGs is 2–5 times higher than for LRGs. Beyond 50 kpc, there is a sharp decline in Mg ii for both kinds of galaxies, indicating a transition to the regime where the CGM is tightly linked with the dark matter halo. The Mg ii-covering fraction correlates strongly with stellar mass for LRGs, but weakly for ELGs, where covering fractions increase with star formation rate. Our analysis implies that cool circumgalactic gas has a different physical origin for star-forming versus quiescent galaxies.

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The Quest for Relics: Massive compact galaxies in the local Universe

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002045 ◽

2019 ◽

Vol 15 (S359) ◽

pp. 441-443

Author(s):

F. S. Lohmann ◽

A. Schnorr-Müller ◽

M. Trevisan ◽

R. Riffel ◽

N. Mallmann ◽

...

Keyword(s):

High Redshift ◽

Control Sample ◽

Sloan Digital Sky Survey ◽

Integral Field Spectroscopy ◽

Sky Survey ◽

Size Evolution ◽

Compact Galaxies ◽

Minor Mergers ◽

Significant Size ◽

Integral Field

AbstractObservations at high redshift reveal that a population of massive, quiescent galaxies (called red nuggets) already existed 10 Gyr ago. These objects undergo a significant size evolution over time, likely due to minor mergers. In this work we present an analysis of local massive compact galaxies to assess if their properties are consistent with what is expected for unevolved red nuggets (relic galaxies). Using integral field spectroscopy (IFS) data from the MaNGA survey from the Sloan Digital Sky Survey (SDSS), we characterized the kinematics and properties of stellar populations of massive compact galaxies, and find that these objects exhibit, on average, a higher rotational support than a control sample of average sized early-type galaxies. This is in agreement with a scenario in which these objects have a quiet accretion history, rendering them candidates for relic galaxies.

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The weak imprint of environment on the stellar populations of galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3545 ◽

2020 ◽

Vol 500 (4) ◽

pp. 4469-4490 ◽

Cited By ~ 1

Author(s):

James Trussler ◽

Roberto Maiolino ◽

Claudia Maraston ◽

Yingjie Peng ◽

Daniel Thomas ◽

...

Keyword(s):

Environmental Effects ◽

Unique Feature ◽

Stellar Populations ◽

Stellar Mass ◽

Sloan Digital Sky Survey ◽

Star Forming ◽

Sky Survey ◽

Satellite Galaxies ◽

Projected Distance ◽

Environmental Dependence

ABSTRACT We investigate the environmental dependence of the stellar populations of galaxies in Sloan Digital Sky Survey Data Release 7 (SDSS DR7). Echoing earlier works, we find that satellites are both more metal-rich (<0.1 dex) and older (<2 Gyr) than centrals of the same stellar mass. However, after separating star-forming, green valley, and passive galaxies, we find that the true environmental dependence of both stellar metallicity (<0.03 dex) and age (<0.5 Gyr) is in fact much weaker. We show that the strong environmental effects found when galaxies are not differentiated result from a combination of selection effects brought about by the environmental dependence of the quenched fraction of galaxies, and thus we strongly advocate for the separation of star-forming, green valley, and passive galaxies when the environmental dependence of galaxy properties are investigated. We also study further environmental trends separately for both central and satellite galaxies. We find that star-forming galaxies show no environmental effects, neither for centrals nor for satellites. In contrast, the stellar metallicities of passive and green valley satellites increase weakly (<0.05 and <0.08 dex, respectively) with increasing halo mass, increasing local overdensity and decreasing projected distance from their central; this effect is interpreted in terms of moderate environmental starvation (‘strangulation’) contributing to the quenching of satellite galaxies. Finally, we find a unique feature in the stellar mass–stellar metallicity relation for passive centrals, where galaxies in more massive haloes have larger stellar mass (∼0.1 dex) at constant stellar metallicity; this effect is interpreted in terms of dry merging of passive central galaxies and/or progenitor bias.

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CONSTRAINTS ON THE SHAPE OF THE MILKY WAY DARK MATTER HALO FROM JEANS EQUATIONS APPLIED TO SLOAN DIGITAL SKY SURVEY DATA

The Astrophysical Journal ◽

10.1088/2041-8205/758/1/l23 ◽

2012 ◽

Vol 758 (1) ◽

pp. L23 ◽

Cited By ~ 14

Author(s):

Sarah R. Loebman ◽

Željko Ivezić ◽

Thomas R. Quinn ◽

Fabio Governato ◽

Alyson M. Brooks ◽

...

Keyword(s):

Dark Matter ◽

Survey Data ◽

Milky Way ◽

Sloan Digital Sky Survey ◽

Dark Matter Halo ◽

Sky Survey

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Are sdAs helium core stars?

Open Astronomy ◽

10.1515/astro-2017-0433 ◽

2017 ◽

Vol 26 (1) ◽

Cited By ~ 4

Author(s):

Ingrid Pelisoli ◽

S. O. Kepler ◽

Detlev Koester

Keyword(s):

Main Sequence ◽

Galactic Disk ◽

Physical Nature ◽

Sloan Digital Sky Survey ◽

Distance Modulus ◽

Main Sequence Stars ◽

Sky Survey ◽

Balmer Lines ◽

Low Mass ◽

Binary Evolution

AbstractEvolved stars with a helium core can be formed by non-conservative mass exchange interaction with a companion or by strong mass loss. Their masses are smaller than 0.5 M⊙. In the database of the Sloan Digital Sky Survey (SDSS), there are several thousand stars which were classified by the pipeline as dwarf O, B and A stars. Considering the lifetimes of these classes on the main sequence, and their distance modulus at the SDSS bright saturation, if these were common main sequence stars, there would be a considerable population of young stars very far from the galactic disk. Their spectra are dominated by Balmer lines which suggest effective temperatures around 8 000-10 000 K. Several thousand have significant proper motions, indicative of distances smaller than 1 kpc. Many show surface gravity in intermediate values between main sequence and white dwarf, 4.75 < log g < 6.5, hence they have been called sdA stars. Their physical nature and evolutionary history remains a puzzle. We propose they are not H-core main sequence stars, but helium core stars and the outcomes of binary evolution. We report the discovery of two new extremely-low mass white dwarfs among the sdAs to support this statement.

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