The "canonical" White Dwarf Cooling Sequence of M5

Abstract

Recently, a new class of white dwarfs (dubbed ``slowly cooling WDs'') has been identified in two globular clusters (namely M13 and NGC 6752) showing a horizontal branch (HB) morphology with an extended blue tail. The cooling rate of these WDs is reduced by stable thermonuclear hydrogen burning in their residual envelope, and they are thought to be originated by stars that populate the blue tail of the HB and then skip the asymptotic giant branch phase. Consistently, no evidence of such kind of WDs has been found in M3, a similar cluster with no blue extension of the HB. To further explore this phenomenon, we took advantage of deep photometric data acquired with the Hubble Space Telescope in the near-ultraviolet and investigate the bright portion of the WD cooling sequence in M5, another Galactic globular cluster with HB morphology similar to M3. The normalized WD luminosity function derived in M5 turns out to be impressively similar to that observed in M3, in agreement with the fact that the stellar mass distribution along the HB of these two systems is almost identical. The comparison with theoretical predictions is consistent with the fact that the cooling sequence in this cluster is populated by canonical (fast cooling) WDs. Thus, the results presented in this paper provide further support to the scenario proposing a direct causal connection between the slow cooling WD phenomenon and the horizontal branch morphology of the host stellar cluster.

12 pages, 8 figures, accepted in the ApJ

References in corpus (20)

• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. I. Overview of the Project and Detection of Multiple Stellar Populations
• Pulsating White Dwarf Stars and Precision Asteroseismology
• Dynamical age differences among coeval star clusters as revealed by blue stragglers
• The updated BaSTI stellar evolution models and isochrones: II. alpha-enhanced calculations
• The White Dwarf Cooling Sequence of NGC6397
• The Ages of the Thin Disk, Thick Disk, and the Halo from Nearby White Dwarfs
• White dwarf evolutionary sequences for low-metallicity progenitors: The impact of third dredge-up
• The Blue Straggler Population of the Globular Cluster M5
• The end of the white dwarf cooling sequence in M 67
• Radio timing and optical photometry of the black widow system PSR J1518+0204C in the globular cluster M5
• A kinematic view of NGC 1261: structural parameters, internal dispersion, absolute proper motion and Blue Straggler Stars
• An extremely low-mass He white dwarf orbiting the millisecond pulsar J1342+2822B in the globular cluster M3
• Star density profiles of six old star clusters in the Large Magellanic Cloud
• Proper motions and structural parameters of the Galactic globular cluster M71
• Discovery of a double sequence of blue straggler stars in the core-collapsed globular cluster NGC 6256
• The Optical Counterpart to the Accreting Millisecond X-ray Pulsar SAX J1748.9-2021 in the Globular Cluster NGC 6440
• Expanding the time domain of multiple populations: evidences of nitrogen variations in the ~1.5 Gyr old star cluster NGC 1783
• Slowly cooling white dwarfs in M13 from stable hydrogen burning
• The HST large programme on NGC 6752 -- IV. The White Dwarf Sequence
• Slowly cooling white dwarfs in NGC 6752

Cited by in corpus (4)

• The dynamical age of the LMC globular cluster NGC 1835 using the "dynamical clock"
• Discovery of an extended Horizontal Branch in the Large Magellanic Cloud globular cluster NGC1835
• Structural parameters, chronological age and dynamical age of the LMC globular cluster NGC 1754
• An excess of luminous white dwarfs in the peculiar Galactic globular cluster NGC 2808